Research Publications
Magnetic field therapy enhances muscle mitochondrial bioenergetics and attenuates systemic ceramide levels following ACL reconstruction: Southeast Asian randomized-controlled pilot trial
Mary C. Stephenson, Lingaraj Krishna, Rina Malathi Pannir Selvan, Yee Kit Tai, Craig Jun Kit Wong, Jocelyn Naixin Yin, Shi-Jie Toh, Federico Torta, Alexander Triebl, Jürg Fröhlich, Christian Beyer, Jing Ze Li, Sara S. Tan, Chun-Kit Wong, Duraimurugan Chinnasamy, Leroy Sivappiragasam Pakkiri, Chester Lee Drum, Markus R. Wenk, John J. Totman, Alfredo Franco-Obregón
Abstract
Metabolic disruption commonly follows Anterior Cruciate Ligament Reconstruction (ACLR) surgery. Brief exposure to low amplitude and frequency pulsed electromagnetic fields (PEMFs) has been shown to promote in vitro and in vivo murine myogeneses via the activation of a calcium–mitochondrial axis conferring systemic metabolic adaptations. This randomized-controlled pilot trial sought to detect local changes in muscle structure and function using MRI, and systemic changes in metabolism using plasma biomarker analyses resulting from ACLR, with or without accompanying PEMF therapy.
Brief exposure to directionally-specific pulsed electromagnetic fields stimulates extracellular vesicle release and is antagonized by streptomycin: A potential regenerative medicine and food industry paradigm
Biomaterials. 2022 Jul 6;287:121658. doi: 10.1016/j.biomaterials.2022.121658.
Craig Jun Kit Wong, Yee Kit Tai, Jasmine Lye Yee Yap, Charlene Hui Hua Fong, Larry Sai Weng Loo, Marek Kukumberg, Jürg Fröhlich, Sitong Zhang, Jing Ze Li, Jiong-Wei Wang, Abdul JalilRufaihah, Alfredo Franco-Obregón
Abstract
Pulsing electromagnetic fields (PEMFs) have been shown to promote in vitro and in vivo myogeneses via mitohormetic survival adaptations of which secretome activation is a key component. A single 10-min exposure of donor myoblast cultures to 1.5 mT amplitude PEMFs produced a conditioned media (pCM) capable of enhancing the myogenesis of recipient cultures to a similar degree as direct magnetic exposure. Downwardly-directed magnetic fields produced greater secretome responses than upwardly-directed fields in adherent and fluid-suspended myoblasts. The suspension paradigm allowed for the rapid concentrating of secreted factors, particularly of extracellular vesicles. The brief conditioning of basal media from magnetically-stimulated myoblasts was capable of conferring myoblast survival to a greater degree than basal media supplemented with fetal bovine serum (5%). Downward-directed magnetic fields, applied directly to cells or in the form of pCM, upregulated the protein expression of TRPC channels, markers for cell cycle progression and myogenesis. Direct magnetic exposure produced mild oxidative stress, whereas pCM provision did not, providing a survival advantage on recipient cells. Streptomycin, a TRP channel antagonist, precluded the production of a myogenic pCM. We present a methodology employing a brief and non-invasive PEMF-exposure paradigm to effectively stimulate secretome production and release for commercial or clinical exploitation.
Mapping genomic loci implicates genes and synaptic biology in schizophrenia
Nature. 2022 Apr 8. doi: 10.1038/s41586-022-04434-5.
Vassily Trubetskoy, Antonio F. Pardiñas, Ting Qi, Georgia Panagiotaropoulou, Swapnil Awasthi, Tim B. Bigdeli, Julien Bryois, Chia-Yen Chen, Charlotte A. Dennison, Lynsey S. Hall, Max Lam, Kyoko Watanabe, Oleksandr Frei, Tian Ge, Janet C. Harwood, Frank Koopmans, Sigurdur Magnusson, Alexander L. Richards, Julia Sidorenko, Yang Wu, Jian Zeng, Jakob Grove, Minsoo Kim, Zhiqiang Li, Georgios Voloudakis, Wen Zhang, Mark Adams, Ingrid Agartz, Elizabeth G. Atkinson, Esben Agerbo, Mariam Al Eissa, Margot Albus, Madeline Alexander, Behrooz Z. Alizadeh, Köksal Alptekin, Thomas D. Als, Farooq Amin, Volker Arolt, Manuel Arrojo, Lavinia Athanasiu, Maria Helena Azevedo, Silviu A. Bacanu, Nicholas J. Bass, Martin Begemann, Richard A. Belliveau, Judit Bene, Beben Benyamin, Sarah E. Bergen, Giuseppe Blasi, Julio Bobes, Stefano Bonassi, Alice Braun, Rodrigo Affonseca Bressan, Evelyn J. Bromet, Richard Bruggeman, Peter F. Buckley, Randy L. Buckner, Jonas Bybjerg-Grauholm, Wiepke Cahn, Murray J. Cairns, Monica E. Calkins, Vaughan J. Carr, David Castle, Stanley V. Catts, Kimberley D. Chambert, Raymond C. K. Chan, Boris Chaumette, Wei Cheng, Eric F. C. Cheung, Siow Ann Chong, David Cohen, Angèle Consoli, Quirino Cordeiro, Javier Costas, Charles Curtis, Michael Davidson, Kenneth L. Davis, Lieuwe de Haan, Franziska Degenhardt, Lynn E. DeLisi, Ditte Demontis, Faith Dickerson, Dimitris Dikeos, Timothy Dinan, Srdjan Djurovic, Jubao Duan, Giuseppe Ducci, Frank Dudbridge, Johan G. Eriksson, Lourdes Fañanás, Stephen V. Faraone, Alessia Fiorentino, Andreas Forstner, Josef Frank, Nelson B. Freimer, Menachem Fromer, Alessandra Frustaci, Ary Gadelha, Giulio Genovese, Elliot S. Gershon, Marianna Giannitelli, Ina Giegling, Paola Giusti-Rodríguez, Stephanie Godard, Jacqueline I. Goldstein, Javier González Peñas, Ana González-Pinto, Srihari Gopal, Jacob Gratten, Michael F. Green, Tiffany A. Greenwood, Olivier Guillin, Sinan Gülöksüz, Raquel E. Gur, Ruben C. Gur, Blanca Gutiérrez, Eric Hahn, Hakon Hakonarson, Vahram Haroutunian, Annette M. Hartmann, Carol Harvey, Caroline Hayward, Frans A. Henskens, Stefan Herms, Per Hoffmann, Daniel P. Howrigan, Masashi Ikeda, Conrad Iyegbe, Inge Joa, Antonio Julià, Anna K. Kähler, Tony Kam-Thong, Yoichiro Kamatani, Sena Karachanak-Yankova, Oussama Kebir, Matthew C. Keller, Brian J. Kelly, Andrey Khrunin, Sung-Wan Kim, Janis Klovins, Nikolay Kondratiev, Bettina Konte, Julia Kraft, Michiaki Kubo, Vaidutis Kučinskas, Zita Ausrele Kučinskiene, Agung Kusumawardhani, Hana Kuzelova-Ptackova, Stefano Landi, Laura C. Lazzeroni, Phil H. Lee, Sophie E. Legge, Douglas S. Lehrer, Rebecca Lencer, Bernard Lerer, Miaoxin Li, Jeffrey Lieberman, Gregory A. Light, Svetlana Limborska, Chih-Min Liu, Jouko Lönnqvist, Carmel M. Loughland, Jan Lubinski, Jurjen J. Luykx, Amy Lynham, Milan Macek Jr, Andrew Mackinnon, Patrik K. E. Magnusson, Brion S. Maher, Wolfgang Maier, Dolores Malaspina, Jacques Mallet, Stephen R. Marder, Sara Marsal, Alicia R. Martin, Lourdes Martorell, Manuel Mattheisen, Robert W. McCarley, Colm McDonald, John J. McGrath, Helena Medeiros, Sandra Meier, Bela Melegh, Ingrid Melle, Raquelle I. Mesholam-Gately, Andres Metspalu, Patricia T. Michie, Lili Milani, Vihra Milanova, Marina Mitjans, Espen Molden, Esther Molina, María Dolores Molto, Valeria Mondelli, Carmen Moreno, Christopher P. Morley, Gerard Muntané, Kieran C. Murphy, Inez Myin-Germeys, Igor Nenadić, Gerald Nestadt, Liene Nikitina-Zake, Cristiano Noto, Keith H. Nuechterlein, Niamh Louise O’Brien, F. Anthony O’Neill, Sang-Yun Oh, Ann Olincy, Vanessa Kiyomi Ota, Christos Pantelis, George N. Papadimitriou, Mara Parellada, Tiina Paunio, Renata Pellegrino, Sathish Periyasamy, Diana O. Perkins, Bruno Pfuhlmann, Olli Pietiläinen, Jonathan Pimm, David Porteous, John Powell, Diego Quattrone, Digby Quested, Allen D. Radant, Antonio Rampino, Mark H. Rapaport, Anna Rautanen, Abraham Reichenberg, Cheryl Roe, Joshua L. Roffman, Julian Roth, Matthias Rothermundt, Bart P. F. Rutten, Safaa Saker-Delye, Veikko Salomaa, Julio Sanjuan, Marcos Leite Santoro, Adam Savitz, Ulrich Schall, Rodney J. Scott, Larry J. Seidman, Sally Isabel Sharp, Jianxin Shi, Larry J. Siever, Engilbert Sigurdsson, Kang Sim, Nora Skarabis, Petr Slominsky, Hon-Cheong So, Janet L. Sobell, Erik Söderman, Helen J. Stain, Nils Eiel Steen, Agnes A. Steixner-Kumar, Elisabeth Stögmann, William S. Stone, Richard E. Straub, Fabian Streit, Eric Strengman, T. Scott Stroup, Mythily Subramaniam, Catherine A. Sugar, Jaana Suvisaari, Dragan M. Svrakic, Neal R. Swerdlow, Jin P. Szatkiewicz, Thi Minh Tam Ta, Atsushi Takahashi, Chikashi Terao, Florence Thibaut, Draga Toncheva, Paul A. Tooney, Silvia Torretta, Sarah Tosato, Gian Battista Tura, Bruce I. Turetsky, Alp Üçok, Arne Vaaler, Therese van Amelsvoort, Ruud van Winkel, Juha Veijola, John Waddington, Henrik Walter, Anna Waterreus, Bradley T. Webb, Mark Weiser, Nigel M. Williams, Stephanie H. Witt, Brandon K. Wormley, Jing Qin Wu, Zhida Xu, Robert Yolken, Clement C. Zai, Wei Zhou, Feng Zhu, Fritz Zimprich, Eşref Cem Atbaşoğlu, Muhammad Ayub, Christian Benner, Alessandro Bertolino, Donald W. Black, Nicholas J. Bray, Gerome Breen, Nancy G. Buccola, William F. Byerley, Wei J. Chen, C. Robert Cloninger, Benedicto Crespo-Facorro, Gary Donohoe, Robert Freedman, Cherrie Galletly, Michael J. Gandal, Massimo Gennarelli, David M. Hougaard, Hai-Gwo Hwu, Assen V. Jablensky, Steven A. McCarroll, Jennifer L. Moran, Ole Mors, Preben B. Mortensen, Bertram Müller-Myhsok, Amanda L. Neil, Merete Nordentoft, Michele T. Pato, Tracey L. Petryshen, Matti Pirinen, Ann E. Pulver, Thomas G. Schulze, Jeremy M. Silverman, Jordan W. Smoller, Eli A. Stahl, Debby W. Tsuang, Elisabet Vilella, Shi-Heng Wang, Shuhua Xu, Indonesia Schizophrenia Consortium, PsychENCODE, Psychosis Endophenotypes International Consortium, The SynGO Consortium, Rolf Adolfsson, Celso Arango, Bernhard T. Baune, Sintia Iole Belangero, Anders D. Børglum, David Braff, Elvira Bramon, Joseph D. Buxbaum, Dominique Campion, Jorge A. Cervilla, Sven Cichon, David A. Collier, Aiden Corvin, David Curtis, Marta Di Forti, Enrico Domenici, Hannelore Ehrenreich, Valentina Escott-Price, Tõnu Esko, Ayman H. Fanous, Anna Gareeva, Micha Gawlik, Pablo V. Gejman, Michael Gill, Stephen J. Glatt, Vera Golimbet, Kyung Sue Hong, Christina M. Hultman, Steven E. Hyman, Nakao Iwata, Erik G. Jönsson, René S. Kahn, James L. Kennedy, Elza Khusnutdinova, George Kirov, James A. Knowles, Marie-Odile Krebs, Claudine Laurent-Levinson, Jimmy Lee, Todd Lencz, Douglas F. Levinson, Qingqin S. Li, Jianjun Liu, Anil K. Malhotra, Dheeraj Malhotra, Andrew McIntosh, Andrew McQuillin, Paulo R. Menezes, Vera A. Morgan, Derek W. Morris, Bryan J. Mowry, Robin M. Murray, Vishwajit Nimgaonkar, Markus M. Nöthen, Roel A. Ophoff, Sara A. Paciga, Aarno Palotie, Carlos N. Pato, Shengying Qin, Marcella Rietschel, Brien P. Riley, Margarita Rivera, Dan Rujescu, Meram C. Saka, Alan R. Sanders, Sibylle G. Schwab, Alessandro Serretti, Pak C. Sham, Yongyong Shi, David St Clair, Hreinn Stefánsson, Kari Stefansson, Ming T. Tsuang, Jim van Os, Marquis P. Vawter, Daniel R. Weinberger, Thomas Werge, Dieter B. Wildenauer, Xin Yu, Weihua Yue, Peter A. Holmans, Andrew J. Pocklington, Panos Roussos, Evangelos Vassos, Matthijs Verhage, Peter M. Visscher, Jian Yang, Danielle Posthuma, Ole A. Andreassen, Kenneth S. Kendler, Michael J. Owen, Naomi R. Wray, Mark J. Daly, Hailiang Huang, Benjamin M. Neale, Patrick F. Sullivan, Stephan Ripke, James T. R. Walters, Michael C. O’Donovan & Schizophrenia Working Group of the Psychiatric Genomics Consortium
Abstract
Schizophrenia has a heritability of 60-80%1, much of which is attributable to common risk alleles. Here, in a two-stage genome-wide association study of up to 76,755 individuals with schizophrenia and 243,649 control individuals, we report common variant associations at 287 distinct genomic loci. Associations were concentrated in genes that are expressed in excitatory and inhibitory neurons of the central nervous system, but not in other tissues or cell types. Using fine-mapping and functional genomic data, we identify 120 genes (106 protein-coding) that are likely to underpin associations at some of these loci, including 16 genes with credible causal non-synonymous or untranslated region variation. We also implicate fundamental processes related to neuronal function, including synaptic organization, differentiation and transmission. Fine-mapped candidates were enriched for genes associated with rare disruptive coding variants in people with schizophrenia, including the glutamate receptor subunit GRIN2A and transcription factor SP4, and were also enriched for genes implicated by such variants in neurodevelopmental disorders. We identify biological processes relevant to schizophrenia pathophysiology; show convergence of common and rare variant associations in schizophrenia and neurodevelopmental disorders; and provide a resource of prioritized genes and variants to advance mechanistic studies.
Blocking CXCL1 signaling for hand, foot and mouth neuropathology
BioCentury Distillery Therapeutics. 2022 Apr 01.
Justin Jang Hann Chu, John Jia En Chua
Abstract
Blocking signaling via the chemokine CXCL1 could help treat neuropathological complications of hand, foot and mouth disease, which is caused by infection with human enterovirus A71. In a rat neuron cell culture model of hand foot and mouth disease, infection with enterovirus A71 induced axonal
disintegration and apoptosis, and a screen for cytokines upregulated after infection identified CXCL1. In CSF samples from infected patients and mice, increased levels of CXCL1 were correlated with increased severity of neurological symptoms. In a mouse model of infection, intracranial
injection of AZD5069, an inhibitor of the CXCL1 receptor CXCR2, extended survival and delayed symptom onset.
BHLHE40 Regulates the T-Cell Effector Function Required for Tumor Microenvironment Remodeling and Immune Checkpoint-Therapy Efficacy
Cancer Immunol Res. 2022 Feb 18;canimm.0129.2021. doi: 10.1158/2326-6066.CIR-21-0129.
Avery J Salmon, Alexander S Shavkunov, Qi Miao, Nicholas N Jarjour, Sunita Keshari, Ekaterina Esaulova, Charmelle D Williams, Jeffrey P Ward, Anna M Highsmith, Josue E Pineda, Reshma Taneja, Ken Chen, Brian T Edelson, Matthew M Gubin
Abstract
Immune checkpoint therapy (ICT) using antibody blockade of PD-1 or CTLA-4 can provoke T cell-dependent antitumor activity that generates durable clinical responses in some patients. The epigenetic and transcriptional features that T cells require for efficacious ICT remain to be fully elucidated. Herein, we report that anti-PD-1 and anti-CTLA-4 ICT induce upregulation of the transcription factor BHLHE40 in tumor antigen-specific CD8+ and CD4+ T cells and that T cells require BHLHE40 for effective ICT in mice bearing immune-edited tumors. Single-cell RNA sequencing of intratumoral immune cells in BHLHE40-deficient mice revealed differential ICT-induced immune cell remodeling. The BHLHE40-dependent gene expression changes indicated dysregulated metabolism, NF-κB signaling, and IFN-γ response within certain subpopulations of CD4+ and CD8+ T cells. Intratumoral CD4+ and CD8+ T cells from BHLHE40-deficient mice exhibited higher expression of the inhibitory receptor gene Tigit and displayed alterations in expression of genes encoding chemokine/chemokine receptors and granzyme family members. Mice lacking BHLHE40 had reduced ICT-driven IFN-γ production by CD4+ and CD8+ T cells and defects in ICT-induced remodeling of macrophages from a CX3CR1+CD206+ subpopulation to an iNOS+ subpopulation that is typically observed during effective ICT. Although both anti-PD-1 and anti-CTLA-4 ICT in BHLHE40-deficient mice led to the same outcome-tumor outgrowth-several BHLHE40-dependent alterations were specific to the ICT that was used. Our results reveal a crucial role for BHLHE40 in effective ICT and suggest that BHLHE40 may be a predictive or prognostic biomarker for ICT efficacy and a potential therapeutic target.
PI3K/AKT Signaling Tips the Balance of Cytoskeletal Forces for Cancer Progression
Cancers 2022, 14(7), 1652. doi: 10.3390/cancers14071652.
Shuo Deng, Hin Chong Leong, Arpita Datta, Vennila Gopal, Alan Prem Kumar and Celestial T. Yap
Abstract
The PI3K/AKT signaling pathway plays essential roles in multiple cellular processes, which include cell growth, survival, metabolism, and motility. In response to internal and external stimuli, the PI3K/AKT signaling pathway co-opts other signaling pathways, cellular components, and cytoskeletal proteins to reshape individual cells. The cytoskeletal network comprises three main components, which are namely the microfilaments, microtubules, and intermediate filaments. Collectively, they are essential for many fundamental structures and cellular processes. In cancer, aberrant activation of the PI3K/AKT signaling cascade and alteration of cytoskeletal structures have been observed to be highly prevalent, and eventually contribute to many cancer hallmarks. Due to their critical roles in tumor progression, pharmacological agents targeting PI3K/AKT, along with cytoskeletal components, have been developed for better intervention strategies against cancer. In our review, we first discuss existing evidence in-depth and then build on recent advances to propose new directions for therapeutic intervention.
The use of sun-shade on safe heat exposure limit on a sunny summer day: a modelling study in Japan
Int J Biometeorol. 2022 Jan 18. doi: 10.1007/s00484-021-02232-8.
Hidenori Otani, Jason K W Lee
Abstract
Sustainable methods are required to reduce the risks of thermal strain and heat-related illness without exacerbating greenhouse gas emissions. We investigated the effects of sun-shade use on safe heat exposure limit on a sunny summer day using historical climate data in Japan. We simulated a heat-acclimatised person standing at rest (metabolic heat production, 70 W·m-2) and during light work (100 W·m-2) on an asphalt pavement in the sun and sun-shade. Japan has three Köppen climate regions: tropical, temperate and cold. We analysed one city in the tropical region (24°N), three cities in the temperate region (31°N, 35°N and 39°N) and one city in the cold region (40°N). Hourly data were collected from 7 AM to 6 PM, June to September, from 2010 to 2019. The day with the longest daylight hours and the greatest solar radiation intensity was used for analysis. With sun-shade (a white polyester tarpaulin/awning), ambient temperature, global solar radiation and ground surface temperature were assumed to be 0.5°C, 45% and 6°C lower than in the sun, respectively. Sun-shade use eliminated the days with at least 1 hour exceeding safe heat exposure limit at rest in all cities. The same was observed for light work in the temperate and cold cities, although the tropical city had 2 days exceeding safe heat exposure limit during the decade. Sun-shade use on a sunny summer day can be an effective and sustainable method to reduce heat exposure hazard at rest and during light work in tropical, temperate and cold climate regions.
PLK1 inhibition selectively induces apoptosis in ARID1A deficient cells through uncoupling of oxygen consumption from ATP production
Oncogene. 2022 Mar 2. doi: 10.1038/s41388-022-02219-8.
Upadhyayula S Srinivas #, Norbert S C Tay #, Patrick Jaynes #, Akshaya Anbuselvan, Gokula K Ramachandran, Joanna D Wardyn, Michal M Hoppe, Phuong Mai Hoang, Yanfen Peng, Sherlly Lim, May Yin Lee, Praveen C Peethala, Omer An, Akshay Shendre, Bryce W Q Tan, Sherlyn Jemimah, Manikandan Lakshmanan, Longyu Hu, Rekha Jakhar, Karishma Sachaphibulkij, Lina H K Lim, Shazib Pervaiz, Karen Crasta, Henry Yang, Patrick Tan, Chao Liang, Lena Ho, Vartika Khanchandani, Dennis Kappei, Wei Peng Yong, David S P Tan, Matteo Bordi, Silvia Campello, Wai Leong Tam, Christian Frezza, Anand D Jeyasekharan
Abstract
Inhibitors of the mitotic kinase PLK1 yield objective responses in a subset of refractory cancers. However, PLK1 overexpression in cancer does not correlate with drug sensitivity, and the clinical development of PLK1 inhibitors has been hampered by the lack of patient selection marker. Using a high-throughput chemical screen, we discovered that cells deficient for the tumor suppressor ARID1A are highly sensitive to PLK1 inhibition. Interestingly this sensitivity was unrelated to canonical functions of PLK1 in mediating G2/M cell cycle transition. Instead, a whole-genome CRISPR screen revealed PLK1 inhibitor sensitivity in ARID1A deficient cells to be dependent on the mitochondrial translation machinery. We find that ARID1A knock-out (KO) cells have an unusual mitochondrial phenotype with aberrant biogenesis, increased oxygen consumption/expression of oxidative phosphorylation genes, but without increased ATP production. Using expansion microscopy and biochemical fractionation, we see that a subset of PLK1 localizes to the mitochondria in interphase cells. Inhibition of PLK1 in ARID1A KO cells further uncouples oxygen consumption from ATP production, with subsequent membrane depolarization and apoptosis. Knockdown of specific subunits of the mitochondrial ribosome reverses PLK1-inhibitor induced apoptosis in ARID1A deficient cells, confirming specificity of the phenotype. Together, these findings highlight a novel interphase role for PLK1 in maintaining mitochondrial fitness under metabolic stress, and a strategy for therapeutic use of PLK1 inhibitors. To translate these findings, we describe a quantitative microscopy assay for assessment of ARID1A protein loss, which could offer a novel patient selection strategy for the clinical development of PLK1 inhibitors in cancer.
Educational dialogue on public perception of nuclear radiation
Int J Radiat Biol. 2022;98(2):158-172. doi: 10.1080/09553002.2022.2009147.
Varsha Hande, Karthik Prathaban, M. Prakash Hande
Abstract
Across the world, nuclear radiation and its effects on the population has been the topic of back-burner debates, given the strong emotional connotations involved. We believe that education is crucial for people to make informed decisions regarding nuclear energy. With a science-technology-society (STS) approach, a seminar-style educational module on Radiation and Society was formulated at Tembusu College, National University of Singapore (NUS) in 2015. This primarily aimed to equip students with the necessary analytical tools to assess evidence and thus, evaluate existing assumptions on radiation/nuclear power/nuclear energy, the effects on mankind and societal perception of radiation.
Alpha-Ketoglutarate dietary supplementation to improve health in humans
Trends Endocrinol Metab. 2022 Feb;33(2):136-146. doi: 10.1016/j.tem.2021.11.003. Epub 2021 Dec 21.
Bibek Gyanwali, Zi Xiang Lim, Janjira Soh, Clarissa Lim, Shou Ping Guan, Jorming Goh, Andrea B Maier, Brian K Kennedy
Abstract
Alpha-ketoglutarate (AKG) is an intermediate in the Krebs cycle involved in various metabolic and cellular pathways. As an antioxidant, AKG interferes in nitrogen and ammonia balance, and affects epigenetic and immune regulation. These pleiotropic functions of AKG suggest it may also extend human healthspan. Recent studies in worms and mice support this concept. A few studies published in the 1980s and 1990s in humans suggested the potential benefits of AKG in muscle growth, wound healing, and in promoting faster recovery after surgery. So far there are no recently published studies demonstrating the role of AKG in treating aging and age-related diseases; hence, further clinical studies are required to better understand the role of AKG in humans. This review will discuss the regulatory role of AKG in aging, as well as its potential therapeutic use in humans to treat age-related diseases.
Pharmacological perturbation of CXCL1 signaling alleviates neuropathogenesis in a model of HEVA71 infection
Nat Commun. 2022 Feb 16;13(1):890. doi: 10.1038/s41467-022-28533-z.
Saravanan Gunaseelan, Mohammed Zacky Ariffin, Sanjay Khanna, Mong How Ooi, David Perera, Justin Jang Hann Chu, John Jia En Chua
Abstract
Hand, foot and mouth disease (HFMD) caused by Human Enterovirus A71 (HEVA71) infection is typically a benign infection. However, in minority of cases, children can develop severe neuropathology that culminate in fatality. Approximately 36.9% of HEVA71-related hospitalizations develop neurological complications, of which 10.5% are fatal. Yet, the mechanism by which HEVA71 induces these neurological deficits remain unclear. Here, we show that HEVA71-infected astrocytes release CXCL1 which supports viral replication in neurons by activating the CXCR2 receptor-associated ERK1/2 signaling pathway. Elevated CXCL1 levels correlates with disease severity in a HEVA71-infected mice model. In humans infected with HEVA71, high CXCL1 levels are only present in patients presenting neurological complications. CXCL1 release is specifically triggered by VP4 synthesis in HEVA71-infected astrocytes, which then acts via its receptor CXCR2 to enhance viral replication in neurons. Perturbing CXCL1 signaling or VP4 myristylation strongly attenuates viral replication. Treatment with AZD5069, a CXCL1-specific competitor, improves survival and lessens disease severity in infected animals. Collectively, these results highlight the CXCL1-CXCR2 signaling pathway as a potential target against HFMD neuropathogenesis.
EHMT1 promotes tumor progression and maintains stemness by regulating ALDH1A1 expression in alveolar rhabdomyosarcoma
J Pathol. 2022 Mar;256(3):349-362. doi: 10.1002/path.5848.
Alamelu Nachiyappan, Joshua Ling Jun Soon, Huey Jin Lim, Victor Km Lee, Reshma Taneja
Abstract
Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer with poor prognosis. Cancer stem cells (CSCs) are seeds for tumor relapse and metastasis. However, pathways that maintain stemness genes are not fully understood. Here, we report that the enzyme euchromatic histone lysine methyltransferase 1 (EHMT1) is expressed in primary and relapse ARMS tumors. EHMT1 suppression impaired motility and induced differentiation in ARMS cell lines and reduced tumor progression in a mouse xenograft model in vivo. RNA sequencing of EHMT1-depleted cells revealed downregulation of ALDH1A1 that is associated with CSCs. Consistent with this, inhibition of ALDH1A1 expression and activity mimicked EHMT1 depletion phenotypes and reduced tumorsphere formation. Mechanistically, we demonstrate that EHMT1 does not bind to the ALDH1A1 promoter but activates it by stabilizing C/EBPβ, a known regulator of ALDH1A1 expression. Our findings identify a role for EHMT1 in maintenance of stemness by regulating ALDH1A1 expression and suggest that targeting ALDH+ cells is a promising strategy in ARMS.
Calcium Channel Splice Variants and Their Effects in Brain and Cardiovascular Function
Adv Exp Med Biol. 2021;1349:67-86. doi: 10.1007/978-981-16-4254-8_5.
Sean Qing Zhang Yeow, Kelvin Wei Zhern Loh, Tuck Wah Soong
Abstract
Calcium ions serve as an important intracellular messenger in many diverse pathways, ranging from excitation coupling in muscles to neurotransmitter release in neurons. Physiologically, the concentration of free intracellular Ca2+ is up to 10,000 times less than that of the extracellular concentration, and increases of 10- to 100-fold in intracellular Ca2+ are observed during signaling events. Voltage-gated calcium channels (VGCCs) located on the plasma membrane serve as one of the main ways in which Ca2+ is able to enter the cell. Given that Ca2+ functions as a ubiquitous intracellular messenger, it is imperative that VGCCs are under tight regulation to ensure that intracellular Ca2+ concentration remains within the physiological range. In this chapter, we explore VGCCs’ inherent control of Ca2+ entry as well as the effects of alternative splicing in CaV2.1 and posttranslational modifications of CaV1.2/CaV1.3 such as phosphorylation and ubiquitination. Deviation from this physiological range will result in deleterious effects known as calcium channelopathies, some of which will be explored in this chapter.
Targeting the molecular & cellular pillars of human aging with exercise
FEBS J. 2021 Dec 30. doi: 10.1111/febs.16337.
Jorming Goh, Esther Wong, Janjira Soh, Andrea Britta Maier, Brian Keith Kennedy
Abstract
Biological aging is the main driver of age-associated chronic diseases. In 2014, the United States National Institute of Aging (NIA) sponsored a meeting between several investigators in the field of aging biology, who identified seven biological pillars of aging and a consensus review, “Geroscience: Linking Aging to Chronic Disease,” was published. The pillars of aging demonstrated the conservation of aging pathways in diverse model organisms and thus represent a useful framework with which to study human aging. In this present review, we revisit the seven pillars of aging from the perspective of exercise and discuss how regular physical exercise can modulate these pillars to stave off age-related chronic diseases and maintain functional capacity.
Shape-Anisotropic Microembolics Generated by Microfluidic Synthesis for Transarterial Embolization Treatment
Adv Healthc Mater. 2022 Feb 2;e2102281. doi: 10.1002/adhm.202102281.
Yucheng Luo, Yutao Ma, Zijian Chen, Yanan Gao, Yuping Zhou, Xiaoya Liu, Xuezhe Liu, Xu Gao, Zhihua Li, Chuang Liu, Hwa Liang Leo, Hanry Yu, Qiongyu Guo
Abstract
Particulate embolic agents with calibrated sizes, which employ interventional procedures to achieve endovascular embolization, have recently attracted tremendous interest in therapeutic embolotherapies for a wide plethora of diseases. However, the particulate shape effect, which may play a critical role in embolization performances, has been rarely investigated. Here, polyvinyl alcohol (PVA)-based shape-anisotropic microembolics are developed using a facile droplet-based microfluidic fabrication method via heat-accelerated PVA-glutaraldehyde crosslinking reaction at a mild temperature of 38 ° C. Precise geometrical controls of the microembolics are achieved with a nearly capsule shape through regulating surfactant concentration and flow rate ratio between dispersed phase and continuous phase in the microfluidics. Two specific models are employed, i.e., in vitro decellularized rabbit liver embolization model and in vivo rabbit ear embolization model, to systematically evaluate the embolization behaviors of the nonspherical microembolics. Compared to microspheres of the same volume, the elongated microembolics demonstrated advantageous endovascular navigation capability, penetration depth and embolization stability due to their comparatively smaller radial diameter and their central cylindrical part providing larger contact area with distal vessels. Such nonspherical microembolics present a promising platform to apply shape anisotropy to achieve distinctive therapeutic effects for endovascular treatments.
Shape memory micro-anchors with magnetic guidance for precision micro-vascular deployment
Biomaterials. 2022 Feb 22;283:121426. doi: 10.1016/j.biomaterials.2022.121426.
Zhihua Li, Zijian Chen, Yanan Gao, Yi Xing, Yuping Zhou, Yucheng Luo, Weihong Xu, Zhengchang Chen, Xu Gao, Kapish Gupta, Karthic Anbalakan, Lei Chen, Chuang Liu, Jian Kong, Hwa Liang Leo, Chengzhi Hu, Hanry Yu, Qiongyu Guo
Abstract
Transcatheter medical micro-devices through circulatory system show great potential for therapy but lack strategies to stably anchor them at the desired site in vascularized tissues to take actions. Here a shape memory functionalized biodegradable magnetic micro-anchor (SM2A) is developed to achieve magnetic guided endovascular localization through precisely controlled shape transformation. The SM2A comprises anisotropic polylactide-based microparticle embedded with superparamagnetic Fe3O4 nanoparticles, exhibiting thermally activated tunable shape recovery modes at a body-friendly temperature range to accomplished an efficient endovascular anchoring effect in both decellularized liver organ and rabbit ear embolization models. The SM2A can be anchored at the target micro-vessel, exhibiting a controlled radial expansion of the vessel wall yielding with estimated stresses of 7-26 kPa in contact stress and 38-218 kPa in von Mises stress. The SM2A is a promising platform to incorporate diagnostic or therapeutic agents for precision deployment and in-situ action.
Modulated TRPC1 Expression Predicts Sensitivity of Breast Cancer to Doxorubicin and Magnetic Field Therapy: Segue Towards a Precision Medicine Approach
Frontiers in Oncology; 2022 Jan 22. DOI: 10.3389/fonc.2021.783803.
Yee Kit Tai, Karen Ka Wing Chan, Charlene Hui Hua Fong, Sharanya Ramanan, Jasmine Lye Yee Yap, Jocelyn Naixin Yin, Yun Sheng Yip, Wei Ren Tan, Angele Pei Fern Koh, Nguan Soon Tan, Ching Wan Chan, Ruby Yun Ju Huang, Jing Ze Li, Jürg Fröhlich and Alfredo Franco-Obregón
Abstract
Chemotherapy is the mainstream treatment modality for invasive breast cancer. Unfortunately, chemotherapy-associated adverse events can result in early termination of treatment. Paradoxical effects of chemotherapy are also sometimes observed, whereby prolonged exposure to high doses of chemotherapeutic agents results in malignant states resistant to chemotherapy. In this study, potential synergism between doxorubicin (DOX) and pulsed electromagnetic field (PEMF) therapy was investigated in: 1) MCF-7 and MDA-MB-231 cells in vitro; 2) MCF-7 tumors implanted onto a chicken chorioallantoic membrane (CAM) and; 3) human patient-derived and MCF-7 and MDA-MB-231 breast cancer xenografts implanted into NOD-SCID gamma (NSG) mice. In vivo, synergism was observed in patient-derived and breast cancer cell line xenograft mouse models, wherein PEMF exposure and DOX administration individually reduced tumor size and increased apoptosis and could be augmented by combined treatments. In the CAM xenograft model, DOX and PEMF exposure also synergistically reduced tumor size as well as reduced Transient Receptor Potential Canonical 1 (TRPC1) channel expression. In vitro, PEMF exposure alone impaired the survival of MCF-7 and MDA-MB-231 cells, but not that of non-malignant MCF10A breast cells; the selective vulnerability of breast cancer cells to PEMF exposure was corroborated in human tumor biopsy samples. Stable overexpression of TRPC1 enhanced the vulnerability of MCF-7 cells to both DOX and PEMF exposure and promoted proliferation, whereas TRPC1 genetic silencing reduced sensitivity to both DOX and PEMF treatments and mitigated proliferation. Chronic exposure to DOX depressed TRPC1 expression, proliferation, and responses to both PEMF exposure and DOX in a manner that was reversible upon removal of DOX. TRPC1 channel overexpression and silencing positively correlated with markers of epithelial-mesenchymal transition (EMT), including SLUG, SNAIL, VIMENTIN, and E-CADHERIN, indicating increased and decreased EMT, respectively. Finally, PEMF exposure was shown to attenuate the invasiveness of MCF-7 cells in correlation with TRPC1 expression. We thus demonstrate that the expression levels of TRPC1 consistently predicted breast cancer sensitivity to DOX and PEMF interventions and positively correlated to EMT status, providing an initial rationale for the use of PEMF-based therapies as an adjuvant to DOX chemotherapy for the treatment of breast cancers characterized by elevated TRPC1 expression levels.
E2F and STAT3 provide transcriptional synergy for histone variant H2AZ activation to sustain glioblastoma chromatin accessibility and tumorigenicity
Cell Death & Differentiation. 2022 January 2022. DOI: 10.1038/s41418-021-00926-5.
Jeehyun Yoon, Oleg V. Grinchuk, Roberto Tirado-Magallanes, Zhen Kai Ngian, Emmy Xue Yun Tay, You Heng Chuah, Bernice Woon Li Lee, Jia Feng, Karen Carmelina Crasta, Chin Tong Ong, Touati Benoukraf & Derrick Sek Tong Ong
Abstract
The histone variant H2AZ is overexpressed in diverse cancer types where it facilitates the accessibility of transcriptional regulators to the promoters of cell cycle genes. However, the molecular basis for its dysregulation in cancer remains unknown. Here, we report that glioblastomas (GBM) and glioma stem cells (GSCs) preferentially overexpress H2AZ for their proliferation, stemness and tumorigenicity. Chromatin accessibility analysis of H2AZ2 depleted GSC revealed that E2F1 occupies the enhancer region within H2AZ2 gene promoter, thereby activating H2AZ2 transcription. Exploration of other H2AZ2 transcriptional activators using a customized “anti-H2AZ2” query signature for connectivity map analysis identified STAT3. Co-targeting E2F and STAT3 synergistically reduced the levels of H2AZ, histone 3 lysine 27 acetylation (H3K27ac) and cell cycle gene transcription, indicating that E2F1 and STAT3 synergize to activate H2AZ gene transcription in GSCs. Remarkably, an E2F/STAT3 inhibitor combination durably suppresses GSC tumorigenicity in an orthotopic GBM xenograft model. In glioma patients, high STAT3 signaling is associated with high E2F1 and H2AZ2 expression. Thus, GBM has uniquely opted the use of E2F1- and STAT3-containing “enhanceosomes” that integrate multiple signaling pathways to achieve H2AZ gene activation, supporting a translational path for the E2F/STAT3 inhibitor combination to be applied in GBM treatment.
EHMT1 promotes tumor progression and maintains stemness by regulating ALDH1A1 expression in alveolar rhabdomyosarcoma
J Pathol. 2021 Dec 12. DOI: 10.1002/path.5848.
Alamelu Nachiyappan, Joshua Ling Jun Soon, Huey Jin Lim, Victor Km Lee, Reshma Taneja
Abstract
Alveolar Rhabdomyosarcoma (ARMS) is an aggressive paediatric cancer with poor prognosis. Cancer stem cells (CSC) are seeds for tumor relapse and metastasis. However, pathways that maintain stemness genes are not fully understood. Here we report that the enzyme Euchromatic Histone Lysine Methyltransferase 1 (EHMT1) is expressed in primary and relapse ARMS tumors. EHMT1 suppression impaired motility and induced differentiation in ARMS cell lines and reduced tumor progression in a mouse xenograft model in vivo. RNA-sequencing of EHMT1-depleted cells revealed downregulation of ALDH1A1 that is associated with CSCs. Consistent with this, inhibition of ALDH1A1 expression and activity mimicked EHMT1 depletion phenotypes and reduced tumorsphere formation. Mechanistically, we demonstrate that EHMT1 does not bind to the ALDH1A1 promoter but activates it by stabilizing C/EBPβ, a known regulator of ALDH1A1 expression. Our findings identify a role for EHMT1 in maintenance of stemness by regulating ALDH1A1 expression and suggest that targeting ALDH+ cells is a promising strategy in ARMS.
Crosstalk Between Inflammatory Signaling and Methylation in Cancer
Front Cell Dev Biol. 2021 Nov 24;9:756458. DOI: 10.3389/fcell.2021.756458. eCollection 2021.
Dipanwita Das, Nandini Karthik, Reshma Taneja
Abstract
Inflammation is an intricate immune response against infection and tissue damage. While the initial immune response is important for preventing tumorigenesis, chronic inflammation is implicated in cancer pathogenesis. It has been linked to various stages of tumor development including transformation, proliferation, angiogenesis, and metastasis. Immune cells, through the production of inflammatory mediators such as cytokines, chemokines, transforming growth factors, and adhesion molecules contribute to the survival, growth, and progression of the tumor in its microenvironment. The aberrant expression and secretion of pro-inflammatory and growth factors by the tumor cells result in the recruitment of immune cells, thus creating a mutual crosstalk. The reciprocal signaling between the tumor cells and the immune cells creates and maintains a successful tumor niche. Many inflammatory factors are regulated by epigenetic mechanisms including DNA methylation and histone modifications. In particular, DNA and histone methylation are crucial forms of transcriptional regulation and aberrant methylation has been associated with deregulated gene expression in oncogenesis. Such deregulations have been reported in both solid tumors and hematological malignancies. With technological advancements to study genome-wide epigenetic landscapes, it is now possible to identify molecular mechanisms underlying altered inflammatory profiles in cancer. In this review, we discuss the role of DNA and histone methylation in regulation of inflammatory pathways in human cancers and review the merits and challenges of targeting inflammatory mediators as well as epigenetic regulators in cancer.
Bhlhe40 function in activated B and TFH cells restrains the GC reaction and prevents lymphomagenesis
J Exp Med. 2022 Feb 7;219(2):e20211406. DOI: 10.1084/jem.20211406.
Rene Rauschmeier, Annika Reinhardt, Charlotte Gustafsson, Vassilis Glaros, Artem V Artemov, Josefine Dunst, Reshma Taneja, Igor Adameyko, Robert Mansson, Meinrad Busslinger, Taras Kreslavsky
Abstract
The generation of high-affinity antibodies against pathogens and vaccines requires the germinal center (GC) reaction, which relies on a complex interplay between specialized effector B and CD4 T lymphocytes, the GC B cells and T follicular helper (TFH) cells. Intriguingly, several positive key regulators of the GC reaction are common for both cell types. Here, we report that the transcription factor Bhlhe40 is a crucial cell-intrinsic negative regulator affecting both the B and T cell sides of the GC reaction. In activated CD4 T cells, Bhlhe40 was required to restrain proliferation, thus limiting the number of TFH cells. In B cells, Bhlhe40 executed its function in the first days after immunization by selectively restricting the generation of the earliest GC B cells but not of early memory B cells or plasmablasts. Bhlhe40-deficient mice with progressing age succumbed to a B cell lymphoma characterized by the accumulation of monoclonal GC B-like cells and polyclonal TFH cells in various tissues.
Neurokinin receptor mechanisms in forebrain medial septum modulate nociception in the formalin model of inflammatory pain
Scientific Reports, volume 11, Article number: 24358 (2021). DOI: 10.1038/s41598-021-03661-6
Si Yun Ng, Mohammed Zacky Ariffin and Sanjay Khanna
Abstract
The present study has explored the hypothesis that neurokinin1 receptors (NK1Rs) in medial septum (MS) modulate nociception evoked on hind paw injection of formalin. Indeed, the NK1Rs in MS are localized on cholinergic neurons which have been implicated in nociception. In anaesthetized rat, microinjection of L-733,060, an antagonist at NK1Rs, into MS antagonized the suppression of CA1 population spike (PS) evoked on peripheral injection of formalin or on intraseptal microinjection of substance P (SP), an agonist at NK1Rs. The CA1 PS reflects the synaptic excitability of pyramidal cells in the region. Furthermore, microinjection of L-733,060 into MS, but not LS, attenuated formalin-induced theta activation in both anaesthetized and awake rat, where theta reflects an oscillatory information processing by hippocampal neurons. The effects of L-733,060 on microinjection into MS were nociceptive selective as the antagonist did not block septo-hippocampal response to direct MS stimulation by the cholinergic receptor agonist, carbachol, in anaesthetized animal or on exploration in awake animal. Interestingly, microinjection of L-733,060 into both MS and LS attenuated formalin-induced nociceptive flinches. Collectively, the foregoing novel findings highlight that transmission at NK1R provide an affective valence to septo-hippocampal information processing and that peptidergic transmission in the septum modulates nociceptive behaviours.
Interplay between Mitochondrial Metabolism and Cellular Redox State Dictates Cancer Cell Survival
Oxid Med Cell Longev. 2021 Nov 3;2021:1341604. DOI: 10.1155/2021/1341604. eCollection 2021.
Brittney Joy-Anne Foo, Jie Qing Eu, Jayshree L Hirpara, Shazib Pervaiz
Abstract
Mitochondria are the main powerhouse of the cell, generating ATP through the tricarboxylic acid cycle (TCA) and oxidative phosphorylation (OXPHOS), which drives myriad cellular processes. In addition to their role in maintaining bioenergetic homeostasis, changes in mitochondrial metabolism, permeability, and morphology are critical in cell fate decisions and determination. Notably, mitochondrial respiration coupled with the passage of electrons through the electron transport chain (ETC) set up a potential source of reactive oxygen species (ROS). While low to moderate increase in intracellular ROS serves as secondary messenger, an overwhelming increase as a result of either increased production and/or deficient antioxidant defenses is detrimental to biomolecules, cells, and tissues. Since ROS and mitochondria both regulate cell fate, attention has been drawn to their involvement in the various processes of carcinogenesis. To that end, the link between a prooxidant milieu and cell survival and proliferation as well as a switch to mitochondrial OXPHOS associated with recalcitrant cancers provide testimony for the remarkable metabolic plasticity as an important hallmark of cancers. In this review, the regulation of cell redox status by mitochondrial metabolism and its implications for cancer cell fate will be discussed followed by the significance of mitochondria-targeted therapies for cancer.
TRAIL sensitivity of nasopharyngeal cancer cells involves redox dependent upregulation of TMTC2 and its interaction with membrane caspase-3
Redox Biol. 2021 Nov 20;48:102193. DOI: 10.1016/j.redox.2021.102193.
Deepika Raman, Patricia Tay, Jayshree L Hirpara, Dan Liu, Shazib Pervaiz
Abstract
Aims: Preferential expression of receptors for TNF-family related apoptosis inducing ligand (TRAIL), DR4 and DR5 makes TRAIL an attractive anti-cancer therapeutic. However, the efficacy of targeting death receptors has not been extensively studied in nasopharyngeal cancer (NPC). Here we investigated TRAIL sensitivity and its underlying mechanism in NPC cell lines, and assessed the potential of TRAIL as a therapeutic option against NPC.
Results: Using two established NPC cell lines, we report the expression of DR4 and DR5, which respond to TRAIL ligation by triggering efficient Type II apoptosis. Mechanistically, early activation of caspase-3 and its membrane recruitment is identified in NPC cell lines, which is associated with, hitherto unreported, interaction with transmembrane and tetratricopeptide repeat containing 2 (TMTC2) in the lipid raft domains. TMTC2 expression is induced upon exposure to TRAIL and involves intracellular increase in peroxynitrite (ONOO-) production. While ONOO- increase is downstream of caspase-8 activation, it is involved in the upregulation of TMTC2, gene knockdown of which abrogated TRAIL-induced apoptotic execution. Bioinformatics analyses also provide evidence for a strong correlation between TMTC2 and DR4 or caspase-3 as well as a significantly better disease-free survival in patients with high TMTC2 expression.
Innovation and conclusion: Collectively, redox-dependent execution of NPC cells upon ligation of TRAIL receptors reintroduces the possible therapeutic use of TRAIL in NPC as well as underscores the potential of using TMTC2 as a biomarker of TRAIL sensitivity.
Identification of a novel catalytic inhibitor of topoisomerase II alpha that engages distinct mechanisms in p53 wt or p53 -/- cells to trigger G2/M arrest and senescence
Cancer Lett. 2021 Nov 26;526:284-303. DOI: 10.1016/j.canlet.2021.11.025.
Soo Fern Lee, Jayshree L Hirpara, Jianhua Qu, Sanjiv K Yadav, Karishma Sachaphibulkij, Shazib Pervaiz
Abstract
We report a novel topoisomerase IIα inhibitor, mercaptopyridine oxide (MPO), which induces G2/M arrest and senescence with distinctly different cell cycle regulators (p21 or p14ARF) in HCT116p 53WT and HCT116 p53-/- cells, respectively. MPO treatment induced defective topoisomerase IIα-mediated decatenation process and inhibition of the enzyme’s catalytic activity that stalled entry into mitosis. Topoisomerase IIα inhibition was associated with ROS-mediated activation of ATM-Chk2 kinase axis in HCT116 p53WT cells, but not in HCT116 p53-/- cells displaying early Chk1 activation. Results suggest that E2F1 stabilization might link MPO-induced p53 phospho-activation in HCT116 p53WT cells or p14ARF induction in HCT116 p53-/- cells. Also, interaction between topoisomerase IIα and Chk1 was induced in both cell lines, which could be important for decatenation checkpoint activation, even upon p53 ablation. Notably, TCGA dataset analyses revealed topoisomerase IIα upregulation across a wide array of cancers, which was associated with lower overall survival. Corroborating that increased topoisomerase IIα expression might offer susceptibility to the novel inhibitor, MPO (5 μM) induced strong inhibition in colony forming ability of pancreatic and hepatocellular cancer cell lines. These data highlight a novel topoisomerase IIα inhibitor and provide proof-of-concept for its therapeutic potential against cancers even with loss-of-function of p53.
The importance of fasciculation and elongation protein zeta-1 in neural circuit establishment and neurological disorders
Neural Regen Res. 2022 Jun;17(6):1165-1171. DOI: 10.4103/1673-5374.327327.
Rafhanah Banu Bte Abdul Razar, Yinghua Qu, Saravanan Gunaseelan, John Jia En Chua
Abstract
The human brain contains an estimated 100 billion neurons that must be systematically organized into functional neural circuits for it to function properly. These circuits range from short-range local signaling networks between neighboring neurons to long-range networks formed between various brain regions. Compelling converging evidence indicates that alterations in neural circuits arising from abnormalities during early neuronal development or neurodegeneration contribute significantly to the etiology of neurological disorders. Supporting this notion, efforts to identify genetic causes of these disorders have uncovered an over-representation of genes encoding proteins involved in the processes of neuronal differentiation, maturation, synaptogenesis and synaptic function. Fasciculation and elongation protein zeta-1, a Kinesin-1 adapter, has emerged as a key central player involved in many of these processes. Fasciculation and elongation protein zeta-1-dependent transport of synaptic cargoes and mitochondria is essential for neuronal development and synapse establishment. Furthermore, it acts downstream of guidance cue pathways to regulate axo-dendritic development. Significantly, perturbing its function causes abnormalities in neuronal development and synapse formation both in the brain as well as the peripheral nervous system. Mutations and deletions of the fasciculation and elongation protein zeta-1 gene are linked to neurodevelopmental disorders. Moreover, altered phosphorylation of the protein contributes to neurodegenerative disorders. Together, these findings strongly implicate the importance of fasciculation and elongation protein zeta-1 in the establishment of neuronal circuits and its maintenance.
Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment
Linda S.H. Gan, Priscilla W.P. Fan, Junren Zhang, Heinrich W. Nolte, Karl E. Friedl, Bradley C.Nindl, Jason K.W.Lee
Abstract
Objectives
To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment.
Design
Prospective cohort design.
Methods
Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase.
Results
Seventeen male participants (age: 24.5 ± 3.2 years, height: 173.9 ± 5.1 cm, body mass: 69.3 ± 3.2 kg, BMI: 22.9 ± 0.9 kg/m2, percent body fat: 14 ± 5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course.
Conclusions
Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts.
Palatable flavoured fluids without carbohydrates and electrolytes do not enhance voluntary fluid consumption in male collegiate basketball players in the heat
Nutrients 2021, 13(12), 4197. DOI: 10.3390/nu13124197
Bernadette Cherianne Taim, Haresh T. Suppiah, Jericho Wee, Marcus Lee, Jason K. W. Lee and Michael Chia
Abstract
Using palatable fluids to enhance drinking in athletes who display insufficient compensatory hydration behaviour may mitigate the risks of hypohydration and performance deficits. However, it is unclear whether flavour can independently enhance fluid consumption. This study examined the effects of a colourless, artificially sweetened flavoured water (FW), without carbohydrates and with negligible amounts of sodium, compared to plain water (W) on fluid consumption in male collegiate basketball players in a practical game setting. Eighteen male basketball players (age 23.1 ± 1.3 years) played a 3v3 basketball small-sided game. The players were randomly assigned to consume either FW or W. Pre-game urine-specific gravity, fluid consumption, body mass, and hedonic taste perceptions were assessed. Basketball performance was analysed through notational analysis. Ratings of perceived exertion and thirst were recorded at pre-, post-game, and at each rest period. Heart rate was recorded throughout the gameplay. Despite significantly higher hedonic ratings for FW than W (6.78 ± 0.83 vs. 5.56 ± 1.33, p = 0.033, d = 1.36), there were no significant differences in fluid consumption (1083 ± 32 mL vs. 1421 ± 403 mL, p = 0.068, d = 0.92). Our result highlighted that using palatable fluids as a strategy to increase fluid consumption during high-intensity gameplay in the heat may not be effective if used without carbohydrates and electrolytes. Practitioners could consider both fluid palatability and composition in establishing a hydration plan for athletes.
The 2021 Report of The Lancet Countdown on Health and Climate Change: Code red for a healthy future
Marina Romanello, Alice McGushin, Claudia Di Napoli, Paul Drummond, Nick Hughes, Louis Jamart, Harry Kennard, Pete Lampard, Baltazar Solano Rodriguez, Prof Nigel Arnell, Sonja Ayeb-Karlsson, Kristine Belesova, Wenjia Cai, Diarmid Campbell-Lendrum, Stuart Capstick, Jonathan Chambers, Lingzhi Chu, Luisa Ciampi, Carole Dalin, Niheer Dasandi, Shouro Dasgupta, Prof Michael Davies, Paula Dominguez-Salas, Prof Robert Dubrow, Prof Kristie L Ebi, Matthew Eckelman, Prof Paul Ekins, Luis E Escobar, Lucien Georgeson, Prof Delia Grace, Prof Hilary Graham, Samuel H Gunther, Stella Hartinger, Kehan He, Clare Heaviside, Jeremy Hess, Shih-Che Hsu, Prof Slava Jankin, Marcia P Jimenez, Prof Ilan Kelman, Gregor Kiesewetter, Prof Patrick L Kinney, Prof Tord Kjellstrom, Prof Dominic Kniveton, Jason K W Lee, Bruno Lemke, Prof Yang Liu, Zhao Liu, Melissa Lott, Rachel Lowe, Prof Jaime Martinez-Urtaza, Prof Mark Maslin, Lucy McAllister, Celia McMichael, Zhifu Mi, James Milner, Kelton Minor, Nahid Mohajeri, Prof Maziar Moradi-Lakeh, Prof Karyn Morrissey, Prof Simon Munzert, Kris A Murray, Tara Neville, Prof Maria Nilsson, Nick Obradovich, Maquins Odhiambo Sewe, Prof Tadj Oreszczyn, Matthias Otto, Fereidoon Owfi, Olivia Pearman, David Pencheon, Mahnaz Rabbaniha, Prof Elizabeth Robinson, Prof Joacim Rocklöv, Renee N Salas, Prof Jan C Semenza, Jodi Sherman, Liuhua Shi, Marco Springmann, Prof Meisam Tabatabaei, Jonathon Taylor, Joaquin Trinanes, Joy Shumake-Guillemot, Bryan Vu, Fabian Wagner, Prof Paul Wilkinson, Matthew Winning, Marisol Yglesias, Shihui Zhang, Prof Peng Gong, Prof Hugh Montgomery, Prof Anthony Costello, Prof Ian Hamilton
Abstract
The Lancet Countdown is an international collaboration that independently monitors the health consequences of a changing climate. Publishing updated, new, and improved indicators each year, the Lancet Countdown represents the consensus of leading researchers from 43 academic institutions and UN agencies. The 44 indicators of this report expose an unabated rise in the health impacts of climate change and the current health consequences of the delayed and inconsistent response of countries around the globe—providing a clear imperative for accelerated action that puts the health of people and planet above all else.
Hydration status and fluid replacement strategies of high-performance adolescent athletes: An application of machine learning to distinguish hydration characteristics
Nutrients 2021, 13(11), 4073. DOI: 10.3390/nu13114073
Haresh T. Suppiah, Ee Ling Ng, Jericho Wee, Bernadette Cherianne Taim, Minh Huynh, Paul B. Gastin, Michael Chia, Chee Yong Low and Jason K. W. Lee
Abstract
There are limited data on the fluid balance characteristics and fluid replenishment behaviors of high-performance adolescent athletes. The heterogeneity of hydration status and practices of adolescent athletes warrant efficient approaches to individualizing hydration strategies. This study aimed to evaluate and characterize the hydration status and fluid balance characteristics of high-performance adolescent athletes and examine the differences in fluid consumption behaviors during training. In total, 105 high-performance adolescent athletes (male: 66, female: 39; age 14.1 ± 1.0 y) across 11 sports had their hydration status assessed on three separate occasions—upon rising and before a low and a high-intensity training session (pre-training). The results showed that 20–44% of athletes were identified as hypohydrated, with 21–44% and 15–34% of athletes commencing low- and high-intensity training in a hypohydrated state, respectively. Linear mixed model (LMM) analyses revealed that athletes who were hypohydrated consumed more fluid (F (1.183.85)) = 5.91, (p = 0.016). Additional K-means cluster analyses performed highlighted three clusters: “Heavy sweaters with sufficient compensatory hydration habits,” “Heavy sweaters with insufficient compensatory hydration habits” and “Light sweaters with sufficient compensatory hydration habits”. Our results highlight that high-performance adolescent athletes with ad libitum drinking have compensatory mechanisms to replenish fluids lost from training. The approach to distinguish athletes by hydration characteristics could assist practitioners in prioritizing future hydration intervention protocols.
Sensory Perception of an oral rehydration solution during exercise in the heat
Nutrients 13(10):3313. DOI:10.3390/nu13103313
Olivia Kitson 1, Kay Rutherfurd-Markwick, Andrew Foskett, Jason Kai Wei Lee,
Charles Diako, Marie Wong and Ajmol Ali
Abstract
Prolonged exercise in the heat elicits a number of physiological changes as glycogen stores are low and water and electrolytes are lost through sweat. However, it is unclear whether these changes provoke an increase in liking of saltiness and, therefore, palatability of an oral rehydration solution (ORS). Twenty-seven recreationally active participants (n= 13 males; n= 14 females) completed sensory analysis of an ORS, a traditional sports drink (TS), and a flavored water placebo (PL) at rest and during 60 min (3×20-min bouts) of cycling exercise at 70% age-predicted maximum heart rate (HRmax) at 35.3±1.4◦C and 41±6% relative humidity. Before and after every 20 min of exercise, drinks were rated (using 20-mL beverage samples) based on liking of sweetness, liking of saltiness, thirst-quenching ability, and overall liking on a nine-point hedonic scale. Hydration status was assessed by changes in semi-nude body mass, saliva osmolality (SOsm), and saliva total protein concentration (SPC). After 60 min of exercise, participants lost 1.36±0.39% (mean±SD) of body mass and there were increases in SOsm and SPC. At all time points, liking of sweetness, saltiness, thirst-quenching ability, and overall liking was higher for the TS and PL compared to the ORS (p< 0.05). However, the saltiness liking and thirst-quenching ability of the ORS increased after 60 min of exercise compared to before exercise (p< 0.05). There was also a change in predictors of overall liking with pre-exercise ratings mostly determined by liking of sweetness, saltiness, and thirst-quenching ability (p< 0.001), whereas only liking of saltiness predicted overall liking post-exercise (R2 = 0.751; p< 0.001). There appears to be a hedonic shift during exercise in which the perception of saltiness becomes the most important predictor of overall liking. This finding supports the potential use of an ORS as a valuable means of hydration during the latter stages of prolonged and/or intense exercise in the heat.
Breaking the vicious circle: Extrachromosomal circular DNA as an emerging player in tumour evolution
Semin Cell Dev Biol. 2021 Nov 29;S1084-9521(21)00291-3. DOI: 10.1016/j.semcdb.2021.11.015.
Matius Robert, Karen Crasta
Abstract
Extrachromosomal circular DNA (ecDNA) or double minutes have gained renewed interest since its discovery more than five decades ago, emerging as potent drivers of tumour evolution. This has largely been motivated by recent discovery that the tumour-exclusive ecDNA are highly prevalent in almost all cancers unlike previously thought. EcDNAs contribute to elevated oncogene expression, intratumoural heterogeneity, tumour adaptation and therapy resistance independently of canonical chromosomal alterations. Importantly, ecDNAs play a critical role in patient survival as ecDNA-based oncogene amplification adversely affects clinical outcome to a significantly greater extent than intrachromosomal amplification. Chromothripsis, a major driver of ecDNA biogenesis and gene amplification, is a mutational process characterised by chromosomal shattering and localised complex genome rearrangement. Chemotherapeutic drugs can lead to chromothriptic rearrangements and therapy resistance. In this review, we examine how ecDNAs mediate oncogene overexpression, facilitate accelerated tumour malignancy and enhance rapid adaptation independently of linear chromosomes. We delve into discoveries pertaining to mechanisms of biogenesis, distinctive features of ecDNA, gene regulation and topological interactions with active chromatin. We also discuss the critical role of chromothripsis in engendering ecDNA amplification and evolution. One envisions that insights into ecDNA biology not only hold importance for the cancer genome and tumour evolutionary dynamics, but could also inform prognostication and clinical intervention, particularly for cancers characterised by high oncogene amplification.
Chromothripsis: A shattered chromosome in the spotlight
Semin Cell Dev Biol. 2021 Nov 25;S1084-9521(21)00303-7. DOI: 10.1016/j.semcdb.2021.11.021.
Karen Crasta
Abstract
No abstract available
Bacterial-induced cell fusion is a danger signal triggering cGAS–STING pathway via micronuclei formation
PNAS July 7, 2020 117 (27) 15923-15934. DOI: 10.1073/pnas.2006908117
Joanne Wei Kay Ku, Yahua Chen, Bryan Jian Wei Lim, Stephan Gasser, Karen Carmelina Crasta, and Yunn-Hwen Gan
Abstract
Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease in the tropics and subtropics with high morbidity and mortality. The facultative intracellular bacterium induces host cell fusion through its type VI secretion system 5 (T6SS5) as an important part of its pathogenesis in mammalian hosts. This allows it to spread intercellularly without encountering extracellular host defenses. We report that bacterial T6SS5-dependent cell fusion triggers type I IFN gene expression in the host and leads to activation of the cGAMP synthase–stimulator of IFN genes (cGAS–STING) pathway, independent of bacterial ligands. Aberrant and abortive mitotic events result in the formation of micronuclei colocalizing with cGAS, which is activated by double-stranded DNA. Surprisingly, cGAS–STING activation leads to type I IFN transcription but not its production. Instead, the activation of cGAS and STING results in autophagic cell death. We also observed type I IFN gene expression, micronuclei formation, and death of chemically induced cell fusions. Therefore, we propose that the cGAS–STING pathway senses unnatural cell fusion through micronuclei formation as a danger signal, and consequently limits aberrant cell division and potential cellular transformation through autophagic death induction.
Increased double strand breaks in diabetic β-cells with a p21 response that limits apoptosis
Scientific Reports volume 9, Article number: 19341 (2019). DOI: 10.1038/s41598-019-54554-8.
Vanessa S. Y. Tay, Surabhi Devaraj, Tracy Koh, Guo Ke, Karen C. Crasta & Yusuf Ali
Abstract
DNA damage and DNA damage response (DDR) pathways in β-cells have received little attention especially in the context of type-2 diabetes. We postulate that p21 plays a key role in DDR by preventing apoptosis, associated through its overexpression triggered by DNA stand breaks (DSBs). Our results show that β-cells from chronic diabetic mice had a greater extent of DSBs as compared to their non-diabetic counterparts. Comet assays and nuclear presence of γH2AX and 53bp1 revealed increased DNA DSBs in 16 weeks old (wo) db/db β-cells as compared to age matched non-diabetic β-cells. Our study of gene expression changes in MIN6 cell line with doxorubicin (Dox) induced DNA damage, showed that the DDR was similar to primary β-cells from diabetic mice. There was significant overexpression of DDR genes, gadd45a and p21 after a 24-hr treatment. Western blot analysis revealed increased cleaved caspase3 over time, suggesting higher frequency of apoptosis due to Dox-induced DNA strand breaks. Inhibition of p21 by pharmacological inhibitor UC2288 under DNA damage conditions (both in Dox-induced MIN6 cells and older db/db islets) significantly increased the incidence of β-cell apoptosis. Our studies confirmed that while DNA damage, specifically DSBs, induced p21 overexpression in β-cells and triggered the p53/p21 cellular response, p21 inhibition exacerbated the frequency of apoptosis.
Exosomes as emerging pro-tumorigenic mediators of the senescence-associated secretory phenotype
Int J Mol Sci. 2019 May 24;20(10):2547. DOI: 10.3390/ijms20102547.
Rekha Jakhar, Karen Crasta
Abstract
Communication between cells is quintessential for biological function and cellular homeostasis. Membrane-bound extracellular vesicles known as exosomes play pivotal roles in mediating intercellular communication in tumor microenvironments. These vesicles and exosomes carry and transfer biomolecules such as proteins, lipids and nucleic acids. Here we focus on exosomes secreted from senescent cells. Cellular senescence can alter the microenvironment and influence neighbouring cells via the senescence-associated secretory phenotype (SASP), which consists of factors such as cytokines, chemokines, matrix proteases and growth factors. This review focuses on exosomes as emerging SASP components that can confer pro-tumorigenic effects in pre-malignant recipient cells. This is in addition to their role in carrying SASP factors. Transfer of such exosomal components may potentially lead to cell proliferation, inflammation and chromosomal instability, and consequently cancer initiation. Senescent cells are known to gather in various tissues with age; eliminating senescent cells or blocking the detrimental effects of the SASP has been shown to alleviate multiple age-related phenotypes. Hence, we speculate that a better understanding of the role of exosomes released from senescent cells in the context of cancer biology may have implications for elucidating mechanisms by which aging promotes cancer and other age-related diseases, and how therapeutic resistance is exacerbated with age.
Lipid accumulation facilitates mitotic slippage-induced adaptation to anti-mitotic drug treatment
Cell Death Discovery volume 4, Article number: 109 (2018). DOI: 10.1038/s41420-018-0127-5
Alex Wong, Sixun Chen, Lay Kien Yang, Yoganathan Kanagasundaram & Karen Crasta
Abstract
Aberrant lipid accumulation is a hallmark of cancer known to contribute to its aggressiveness and malignancy. Emerging studies have demonstrated context-dependent changes in lipid metabolism during chemotherapy. However, there is little known regarding the mechanisms linking lipid metabolism to chemotherapy-induced cell fates. Here, we describe lipid accumulation in cells following antimitotic drug treatment. Cells arrested in mitosis, as well as cells that escaped mitotic arrest and underwent mitotic slippage, showed elevated cytoplasmic lipid droplets. Interestingly, we found that TOFA, a lipid biosynthesis inhibitor that targets acetyl-CoA carboxylase (ACC) and blocks lipid accumulation, promoted early slippage, reduced cellular stress and enhanced survival of antimitotic-treated cells. Our work previously revealed that cells that survive after mitotic slippage can become senescent and confer pro-tumourigenic effects through paracrine signalling. Modulating lipid biosynthesis in cells post slippage by TOFA amplified their inflammatory secretion profiles and accelerated the development of tumourigenic behaviour, particularly cell migration and invasion, in a paracrine-dependent manner. In contrast to TOFA, inhibition of lipid accumulation by C75, a drug targeting fatty acid synthase (FASN), significantly reduced the production of pro-tumourigenic factors and associated phenotypic effects. This suggests that discrete lipid biosynthesis pathways could contribute differentially to the regulation of pro-tumourigenic inflammation. The divergent effects of TOFA and C75 may be attributed to the opposing regulation of Malonyl-CoA, an intermediate in fatty acid synthesis that serves as a mediator of fatty acid oxidation. Taken together, our data reveal a previously unappreciated role for lipid accumulation in the cellular adaptation to antimitotic drug treatment. Targeting lipid biosynthesis in cells post slippage may reprogramme its secretory profile such that it not only negates tumour-promoting effects, but may also promote anti-tumour inflammation for clearance of post-slippage senescent cells.
Dropping in on lipid droplets: insights into cellular stress and cancer
Biosci Rep. 2018 Sep 19;38(5):BSR20180764. DOI: 10.1042/BSR20180764.
Peter Shyu Jr, Xing Fah Alex Wong, Karen Crasta, Guillaume Thibault
Abstract
Lipid droplets (LD) have increasingly become a major topic of research in recent years following its establishment as a highly dynamic organelle. Contrary to the initial view of LDs being passive cytoplasmic structures for lipid storage, studies have provided support on how they act in concert with different organelles to exert functions in various cellular processes. Although lipid dysregulation resulting from aberrant LD homeostasis has been well characterised, how this translates and contributes to cancer progression is poorly understood. This review summarises the different paradigms on how LDs function in the regulation of cellular stress as a contributing factor to cancer progression. Mechanisms employed by a broad range of cancer cell types in differentially utilising LDs for tumourigenesis will also be highlighted. Finally, we discuss the potential of targeting LDs in the context of cancer therapeutics.
Chromosomal instability-induced senescence potentiates cell non-autonomous tumourigenic effects
Oncogenesis volume 7, Article number: 62 (2018). DOI: 10.1038/s41389-018-0072-4.
Qianqian He, Bijin Au, Madhura Kulkarni, Yang Shen, Kah. J. Lim, Jiamila Maimaiti, Cheng. Kit. Wong, Monique. N. H. Luijten, Han C. Chong, Elaine H. Lim, Giulia Rancati, Indrajit Sinha, Zhiyan Fu, Xiaomeng Wang, John. E. Connolly & Karen C. Crasta
Abstract
Chromosomal instability (CIN), a high rate of chromosome loss or gain, is often associated with poor prognosis and drug resistance in cancers. Aneuploid, including near-polyploid, cells contain an abnormal number of chromosomes and exhibit CIN. The post-mitotic cell fates following generation of different degrees of chromosome mis-segregation and aneuploidy are unclear. Here we used aneuploidy inducers, nocodazole and reversine, to create different levels of aneuploidy. A higher extent of aneuploid and near-polyploid cells in a given population led to senescence. This was in contrast to cells with relatively lower levels of abnormal ploidy that continued to proliferate. Our findings revealed that senescence was accompanied by DNA damage and robust p53 activation. These senescent cells acquired the senescence-associated secretory phenotype (SASP). Depletion of p53 reduced the number of senescent cells with concomitant increase in cells undergoing DNA replication. Characterisation of these SASP factors demonstrated that they conferred paracrine pro-tumourigenic effects such as invasion, migration and angiogenesis both in vitro and in vivo. Finally, a correlation between increased aneuploidy and senescence was observed at the invasive front in breast carcinomas. Our findings demonstrate functional non-equivalence of discernable aneuploidies on tumourigenesis and suggest a cell non-autonomous mechanism by which aneuploidy-induced senescent cells and SASP can affect the tumour microenvironment to promote tumour progression.
Autophagy Governs Protumorigenic Effects of Mitotic Slippage-induced Senescence
Mol Cancer Res. 2018 Nov;16(11):1625-1640. DOI: 10.1158/1541-7786.MCR-18-0024.
Rekha Jakhar, Monique N H Luijten, Alex X F Wong, Bing Cheng, Ke Guo, Suat P Neo, Bijin Au, Madhura Kulkarni, Kah J Lim, Jiamila Maimaiti, Han C Chong, Elaine H Lim, Tee B K Tan, Kong W Ong, Yirong Sim, Jill S L Wong, James B K Khoo, Juliana T S Ho, Boon T Chua, Indrajit Sinha, Xiaomeng Wang, John E Connolly, Jayantha Gunaratne, Karen C Crasta
Abstract
The most commonly utilized class of chemotherapeutic agents administered as a first-line therapy are antimitotic drugs; however, their clinical success is often impeded by chemoresistance and disease relapse. Hence, a better understanding of the cellular pathways underlying escape from cell death is critical. Mitotic slippage describes the cellular process where cells exit antimitotic drug-enforced mitotic arrest and “slip” into interphase without proper chromosome segregation and cytokinesis. The current report explores the cell fate consequence following mitotic slippage and assesses a major outcome following treatment with many chemotherapies, therapy-induced senescence. It was found that cells postslippage entered senescence and could impart the senescence-associated secretory phenotype (SASP). SASP factor production elicited paracrine protumorigenic effects, such as migration, invasion, and vascularization. Both senescence and SASP factor development were found to be dependent on autophagy. Autophagy induction during mitotic slippage involved the autophagy activator AMPK and endoplasmic reticulum stress response protein PERK. Pharmacologic inhibition of autophagy or silencing of autophagy-related ATG5 led to a bypass of G1 arrest senescence, reduced SASP-associated paracrine tumorigenic effects, and increased DNA damage after S-phase entry with a concomitant increase in apoptosis. Consistent with this, the autophagy inhibitor chloroquine and microtubule-stabilizing drug paclitaxel synergistically inhibited tumor growth in mice. Sensitivity to this combinatorial treatment was dependent on p53 status, an important factor to consider before treatment.Implications: Clinical regimens targeting senescence and SASP could provide a potential effective combinatorial strategy with antimitotic drugs. Mol Cancer Res; 16(11); 1625-40. ©2018 AACR.
Mutational game changer: Chromothripsis and its emerging relevance to cancer
Monique Nicole Helena Luijten, Jeannie Xue Ting Lee, Karen CarmelinaCrasta
Abstract
In recent years, the paradigm that genomic abnormalities in cancer cells arise through progressive accumulation of mutational events has been challenged by the discovery of single catastrophic events. One such phenomenon termed chromothripsis, involving massive chromosomal rearrangements arising all at once, has emerged as a major mutational game changer. The strong interest in this process stems from its widespread association with a range of cancer types and its potential as a mutational driver.
In this review, we first describe chromothripsis detection and incidence in cancers. We then explore recently proposed underlying mechanistic origins, which explain the curious observations of the highly localised nature of the rearrangements on chromothriptic chromosomes. Detection of chromothriptic patterns following incorporation of single chromosomes into micronuclei or following telomere attrition have greatly contributed to our understanding of the reasons behind this chromosomal restriction. These underlying cellular events have been found to be participants in the tumourigenic process, strongly suggesting a potential role for chromothripsis in cancer development. Thus, we discuss potential implications of chromothripsis for cancer progression and therapy.
Consequences of mitotic slippage for anti-microtubule therapy
Endocr Relat Cancer. 2017 Sep;24(9):T97-T106. DOI: 10.1530/ERC-17-0147.
Bing Cheng, Karen Crasta
Abstract
Antimicrotubule agents are commonly utilised as front-line therapies against several malignancies, either by themselves or as combination therapies. Cell-based studies have pinpointed the anti-proliferative basis of action to be a consequence of perturbation of microtubule dynamics leading to sustained activation of the spindle assembly checkpoint, prolonged mitotic arrest and mitotic cell death. However, depending on the biological context and cell type, cells may take an alternative route besides mitotic cell death via a process known as mitotic slippage. Here, mitotically arrested cells ‘slip’ to the next interphase without undergoing proper chromosome segregation and cytokinesis. These post-slippage cells in turn have two main cell fates, either cell death or a G1 arrest ensuing in senescence. In this review, we take a look at the factors determining mitotic cell death vs mitotic slippage, post-slippage cell fates and accompanying features, and their consequences for antimicrotubule drug treatment outcomes.
DNA breaks and chromosome pulverization from errors in mitosis
Nature. 2012 Jan 18;482(7383):53-8. DOI: 10.1038/nature10802.
Karen Crasta, Neil J Ganem, Regina Dagher, Alexandra B Lantermann, Elena V Ivanova, Yunfeng Pan, Luigi Nezi, Alexei Protopopov, Dipanjan Chowdhury, David Pellman
Abstract
The involvement of whole-chromosome aneuploidy in tumorigenesis is the subject of debate, in large part because of the lack of insight into underlying mechanisms. Here we identify a mechanism by which errors in mitotic chromosome segregation generate DNA breaks via the formation of structures called micronuclei. Whole-chromosome-containing micronuclei form when mitotic errors produce lagging chromosomes. We tracked the fate of newly generated micronuclei and found that they undergo defective and asynchronous DNA replication, resulting in DNA damage and often extensive fragmentation of the chromosome in the micronucleus. Micronuclei can persist in cells over several generations but the chromosome in the micronucleus can also be distributed to daughter nuclei. Thus, chromosome segregation errors potentially lead to mutations and chromosome rearrangements that can integrate into the genome. Pulverization of chromosomes in micronuclei may also be one explanation for ‘chromothripsis’ in cancer and developmental disorders, where isolated chromosomes or chromosome arms undergo massive local DNA breakage and rearrangement.
Educational dialogue on public perception of nuclear radiation
International Journal of Radiation Biology, in press. DOI: 10.1080/09553002.2022.2009147
Varsha Hande, Karthik Prathaban & M. Prakash Hande
Abstract
Across the world, nuclear radiation and its effects on the population has been the topic of back-burner debates, given the strong emotional connotations involved. We believe that education is crucial for people to make informed decisions regarding nuclear energy. With a science-technology-society (STS) approach, a seminar-style educational module on Radiation and Society was formulated at Tembusu College, National University of Singapore (NUS) in 2015. This primarily aimed to equip students with the necessary analytical tools to assess evidence and thus, evaluate existing assumptions on radiation/nuclear power/nuclear energy, the effects on mankind and societal perception of radiation.
Novel Autoantibodies in Idiopathic Small Fiber Neuropathy
Annals of Neurology, in press. DOI: 10.1002/ana.26268
Amanda C. Y. Chan, Hiu Yi Wong, Yao Feng Chong, Poh San Lai, Hock Luen Teoh, Alison Y. Y. Ng, Jennifer H. M. Hung, Yee Cheun Chan, Kay W. P. Ng, Joy Vijayan, Jonathan J. Y. Ong, Bharatendu Chandra, Chi Hsien Tan, Nurul H. Rutt, Ti Myen Tan, Nur Hafiza Ismail, Einar Wilder-Smith, Herbert Schwarz, Hyungwon Choi, Vijay K. Sharma, Anselm Mak
Abstract
Objective
Small fiber neuropathy (SFN) is clinically and etiologically heterogeneous. Although autoimmunity has been postulated to be pathophysiologically important in SFN, few autoantibodies have been described. We aimed to identify autoantibodies associated with idiopathic SFN (iSFN) by a novel high-throughput protein microarray platform that captures autoantibodies expressed in the native conformational state.
Methods
Sera from 58 SFN patients and 20 age- and gender-matched healthy controls (HCs) were screened against >1,600 immune-related antigens. Fluorescent unit readout and postassay imaging were performed, followed by composite data normalization and protein fold change (pFC) analysis. Analysis of an independent validation cohort of 33 SFN patients against the same 20 HCs was conducted to identify reproducible proteins in both cohorts.
Results
Nine autoantibodies were screened with statistical significance and pFC criteria in both cohorts, with at least 50% change in serum levels. Three proteins showed consistently high fold changes in main and validation cohorts: MX1 (FC = 2.99 and 3.07, respectively, p = 0.003, q = 0.076), DBNL (FC = 2.11 and 2.16, respectively, p = 0.009, q < 0.003), and KRT8 (FC = 1.65 and 1.70, respectively, p = 0.043, q < 0.003). Further subgroup analysis into iSFN and SFN by secondary causes (secondary SFN) in the main cohort showed that MX1 is higher in iSFN compared to secondary SFN (FC = 1.61 vs 0.106, p = 0.009).
Interpretation
Novel autoantibodies MX1, DBNL, and KRT8 are found in iSFN. MX1 may allow diagnostic subtyping of iSFN patients. ANN NEUROL 2021
Dendritic cell therapy with CD137L-DC-EBV-VAX in locally recurrent or metastatic nasopharyngeal carcinoma is safe and confers clinical benefit
Cancer Immunol Immunother. 2021 Oct 18. DOI: 10.1007/s00262-021-03075-3.
Emily Nickles, Bhushan Dharmadhikari, Li Yating, Robert J Walsh, Liang Piu Koh, Michelle Poon, Lip Kun Tan, Ling-Zhi Wang, Yvonne Ang, Yugarajah Asokumaran, Wan Qin Chong, Yiqing Huang, Kwok Seng Loh, Joshua Tay, Ross Soo, Mickey Koh, Liam Pock Ho, Marieta Chan, Madelaine Niam, Melissa Soh, Yen Hoon Luah, Chwee Ming Lim, Nivashini Kaliaperumal, Veonice B Au, Najwa Binte Said Nasir Talib, Reina Sng, John E Connolly, Boon Cher Goh, Herbert Schwarz
Abstract
Introduction: Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC), and provides a target for a dendritic cell (DC) vaccine. CD137 ligand (CD137L) expressed on antigen presenting cells, costimulates CD137-expressing T cells, and reverse CD137L signaling differentiates monocytes to CD137L-DC, a type of DC, which is more potent than classical DC in stimulating T cells.
Methods: In this phase I study, patients with locally recurrent or metastatic NPC were administered CD137L-DC pulsed with EBV antigens (CD137L-DC-EBV-VAX).
Results: Of the 12 patients treated, 9 received full 7 vaccine doses with a mean administered cell count of 23.9 × 106 per dose. Treatment was well tolerated with only 4 cases of grade 1 related adverse events. A partial response was obtained in 1 patient, and 4 patients are still benefitting from a progression free survival (PFS) of currently 2-3 years. The mean pre-treatment neutrophil: lymphocyte ratio was 3.4 and a value of less than 3 was associated with prolonged median PFS. Progressors were characterized by a high frequency of naïve T cells but a low frequency of CD8+ effector T cells while patients with a clinical benefit (CB) had a high frequency of memory T cells. Patients with CB had lower plasma EBV DNA levels, and a reduction after vaccination.
Conclusion: CD137L-DC-EBV-VAX was well tolerated. The use of CD137L-DC-EBV-VAX is demonstrated to be safe. Consistent results were obtained from all 12 patients, indicating that CD137L-DC-EBV-VAX induces an anti-EBV and anti-NPC immune response, and warranting further studies in patients post effective chemotherapy.
Precis: The first clinical testing of CD137L-DC, a new type of monocyte-derived DC, finds that CD137L-DC are safe, and that they can induce an immune response against Epstein-Barr virus-associated nasopharyngeal carcinoma that leads to tumor regression or prevents tumor progression.
No crossreactivity of anti-SARS-CoV-2 spike protein antibodies with Syncytin-1
Cell Mol Immunol. 2021 Nov;18(11):2566-2568. DOI: 10.1038/s41423-021-00773-x.
Mukul Prasad, Jia Le Lin, Yue Gu, Rashi Gupta, Paul Macary, Herbert Schwarz
Abstract
SARS-CoV-2, as well as the measures that were taken around the world to limit its spread, has killed thousands of people and ruined industries and economies. Vigorous vaccination campaigns are being pursued in the hope of ending the pandemic. However, many people are afraid of vaccination side effects, and one of these suspected side effects is female infertility due to vaccine-induced autoreactive antibodies against Syncytin-1 [1]. The spike protein of SARS-CoV-2, which is the main target of all vaccination schemes, shares homology to Syncytin-1. Syncytin-1 enables the fusion of trophoblasts to syncytiotrophoblasts, cells that are essential for placenta formation, an early step in the establishment of a pregnancy [2, 3].
B7-H7 Is Inducible on T Cells to Regulate Their Immune Response and Serves as a Marker for Exhaustion
Front Immunol. 2021; 12: 682627. DOI: 10.3389/fimmu.2021.682627
Khang Luu, Herbert Schwarz, and Andreas Lundqvist
Abstract
The discovery of immune checkpoints highlights the complexity of T cell signalling during an immune response. Upon activation, T cells express several molecules to regulate their function and to prevent overactivation. B7 homolog 7 (B7-H7) is expressed in tumours and associated with a worse prognosis. However, conflicting data regarding its function suggest that it can be both stimulatory and inhibitory. In this study we report that B7-H7 is also expressed on T cells upon cross-linking of CD3 and CD28 and that additional stimulation via CD137 further enhances the expression of B7-H7. B7-H7 is preferentially expressed on exhausted Th1 and Tc1 cells with an impaired secretion of TNF-α and IFN-γ. Blockade of B7-H7 with its natural receptor, recombinant CD28H, enhances T cell proliferation and activation. Thus, B7-H7 represents another target for immunotherapy and a biomarker to select for active effector T cells with relevance for adoptive cell transfer therapy.
Regulatory T Cells Inhibit T Cell Activity by Downregulating CD137 Ligand via CD137 Trogocytosis
Cells. 2021 Feb 9;10(2):353. DOI: 10.3390/cells10020353.
Khang Luu, Mugdha Vijay Patwardhan, Qun Zeng, Stina L Wickström, Andreas Lundqvist, Herbert Schwarz
Abstract
CD137 is a costimulatory molecule expressed on activated T cells. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC), which use the CD137-CD137L system to enhance immune responses. It was, therefore, surprising to discover CD137 expression on regulatory T cells (Treg). The function of CD137 in Treg are controversial. While some studies report that CD137 signalling converts Treg to effector T cells (Teff), other studies find that CD137-expressing Treg display a stronger inhibitory activity than CD137- Treg. Here, we describe that CD137 on Treg binds to CD137L on APC, upon which one of the two molecules is transferred via trogocytosis to the other cell, where CD137-CD137L forms a complex that is internalized and deprives APC of the immune-stimulatory CD137L. Truncated forms of CD137 that lack the cytoplasmic domain of CD137 are also able to downregulate CD137L, demonstrating that CD137 signalling is not required. Comparable data have been obtained with human and murine cells, indicating that this mechanism is evolutionarily conserved. These data describe trogocytosis of CD137 and CD137L as a new mechanism employed by Treg to control immune responses by downregulating the immunostimulatory CD137L on APC.
Integrated Genomic Profiling and Drug Screening of Patient-Derived Cultures Identifies Individualized Copy Number-Dependent Susceptibilities Involving PI3K Pathway and 17q Genes in Neuroblastoma
Front Oncol. 2021 Oct 14;11:709525. DOI: 10.3389/fonc.2021.709525. eCollection 2021.
Rachel L Y Wong, Megan R E Wong, Chik Hong Kuick, Seyed Ehsan Saffari, Meng Kang Wong, Sheng Hui Tan, Khurshid Merchant, Kenneth T E Chang, Matan Thangavelu, Giridharan Periyasamy, Zhi Xiong Chen, Prasad Iyer, Enrica E K Tan, Shui Yen Soh, N Gopalakrishna Iyer, Qiao Fan, Amos H P Loh
Abstract
Neuroblastoma is the commonest extracranial pediatric malignancy. With few recurrent single nucleotide variations (SNVs), mutation-based precision oncology approaches have limited utility, but its frequent and heterogenous copy number variations (CNVs) could represent genomic dependencies that may be exploited for personalized therapy. Patient-derived cell culture (PDC) models can facilitate rapid testing of multiple agents to determine such individualized drug-responses. Thus, to study the relationship between individual genomic aberrations and therapeutic susceptibilities, we integrated comprehensive genomic profiling of neuroblastoma tumors with drug screening of corresponding PDCs against 418 targeted inhibitors. We quantified the strength of association between copy number and cytotoxicity, and validated significantly correlated gene-drug pairs in public data and using machine learning models. Somatic mutations were infrequent (3.1 per case), but copy number losses in 1p (31%) and 11q (38%), and gains in 17q (69%) were prevalent. Critically, in-vitro cytotoxicity significantly correlated only with CNVs, but not SNVs. Among 1278 significantly correlated gene-drug pairs, copy number of GNA13 and DNA damage response genes CBL, DNMT3A, and PPM1D were most significantly correlated with cytotoxicity; the drugs most commonly associated with these genes were PI3K/mTOR inhibitor PIK-75, and CDK inhibitors P276-00, SNS-032, AT7519, flavopiridol and dinaciclib. Predictive Markov random field models constructed from CNVs alone recapitulated the true z-score-weighted associations, with the strongest gene-drug functional interactions in subnetworks involving PI3K and JAK-STAT pathways. Together, our data defined individualized dose-dependent relationships between copy number gains of PI3K and STAT family genes particularly on 17q and susceptibility to PI3K and cell cycle agents in neuroblastoma. Integration of genomic profiling and drug screening of patient-derived models of neuroblastoma can quantitatively define copy number-dependent sensitivities to targeted inhibitors, which can guide personalized therapy for such mutationally quiet cancers.
Plk1 in Asthma – Ready for Primetime?
Am J Respir Cell Mol Biol. 2021 Nov 8. DOI: 10.1165/rcmb.2021-0425ED.
John Kit Chung Tam, Thai Tran
Abstract
No abstract available
Tetraspanins: Host Factors in Viral Infections
Int J Mol Sci. 2021 Oct 27;22(21):11609. DOI: 10.3390/ijms222111609.
ChihSheng New, Zhao-Yong Lee, Kai Sen Tan, Amanda Huee-Ping Wong, De Yun Wang, Thai Tran
Abstract
Tetraspanins are transmembrane glycoproteins that have been shown increasing interest as host factors in infectious diseases. In particular, they were implicated in the pathogenesis of both non-enveloped (human papillomavirus (HPV)) and enveloped (human immunodeficiency virus (HIV), Zika, influenza A virus, (IAV), and coronavirus) viruses through multiple stages of infection, from the initial cell membrane attachment to the syncytium formation and viral particle release. However, the mechanisms by which different tetraspanins mediate their effects vary. This review aimed to compare and contrast the role of tetraspanins in the life cycles of HPV, HIV, Zika, IAV, and coronavirus viruses, which cause the most significant health and economic burdens to society. In doing so, a better understanding of the relative contribution of tetraspanins in virus infection will allow for a more targeted approach in the treatment of these diseases.
Sex-specific accelerated decay in time/activity-dependent plasticity and associative memory in an animal model of Alzheimer’s disease
Aging Cell. 2021 Nov 18;e13502. DOI: 10.1111/acel.13502.
Sheeja Navakkode, Jessica Ruth Gaunt, Maria Vazquez Pavon, Vibhavari Aysha Bansal, Riya Prasad Abraham, Yee Song Chong, Toh Hean Ch’ng, Sreedharan Sajikumar
Abstract
Clinical studies have shown that female brains are more predisposed to neurodegenerative diseases such as Alzheimer’s disease (AD), but the cellular and molecular mechanisms behind this disparity remain unknown. In several mouse models of AD, synaptic plasticity dysfunction is an early event and appears before significant accumulation of amyloid plaques and neuronal degeneration. However, it is unclear whether sexual dimorphism at the synaptic level contributes to the higher risk and prevalence of AD in females. Our studies on APP/PS1 (APPSwe/PS1dE9) mouse model show that AD impacts hippocampal long-term plasticity in a sex-specific manner. Long-term potentiation (LTP) induced by strong tetanic stimulation (STET), theta burst stimulation (TBS) and population spike timing-dependent plasticity (pSTDP) show a faster decay in AD females compared with age-matched AD males. In addition, behavioural tagging (BT), a model of associative memory, is specifically impaired in AD females with a faster decay in memory compared with males. Together with the plasticity and behavioural data, we also observed an upregulation of neuroinflammatory markers, along with downregulation of transcripts that regulate cellular processes associated with synaptic plasticity and memory in females. Immunohistochemistry of AD brains confirms that female APP/PS1 mice carry a higher amyloid plaque burden and have enhanced microglial activation compared with male APP/PS1 mice. Their presence in the diseased mice also suggests a link between the impairment of LTP and the upregulation of the inflammatory response. Overall, our data show that synaptic plasticity and associative memory impairments are more prominent in females and this might account for the faster progression of AD in females.
Deciphering nanoparticle trafficking into glioblastomas uncovers an augmented antitumor effect of metronomic chemotherapy
Adv Mater. 2021 Nov 2;e2106194. DOI: 10.1002/adma.202106194.
Melgious Jin Yan Ang, Jeehyun Yoon, Mingzhu Zhou, Han-Lin Wei, Yi Yiing Goh, Zhenglin Li, Jia Feng, Haifang Wang, Qianqian Su, Derrick Sek Tong Ong, Xiaogang Liu
Abstract
Nanoparticles have been explored in glioblastomas as they can traverse the blood-brain barrier and target glioblastoma selectively. However, direct observation of nanoparticle trafficking into glioblastoma cells and their underlying intracellular fate after systemic administration remains uncharacterized. Here, based on transmission electron microscopy experiments of an intracranial glioblastoma model, we show that ligand-modified nanoparticles can traverse the blood-brain barrier, endocytose into the lysosomes of glioblastoma cells, and undergo endo-lysosomal escape upon photochemical ionization. Moreover, an optimal dose of metronomic chemotherapy using dual drug-loaded nanocarriers can induce an augmented antitumor effect directly on tumors, which was not recognized in previous studies. Metronomic chemotherapy enhances antitumor effects 3.5-fold compared with the standard chemotherapy regimen using the same accumulative dose in vivo. This study provides a conceptual framework that can be used to develop metronomic nanoparticle regimens as a safe and viable therapeutic strategy for treating glioblastomas and other advanced-stage solid tumors. This article is protected by copyright. All rights reserved.
Metaplastic reinforcement of long-term potentiation in hippocampal area CA2 by cholinergic receptor activation
J Neurosci. 2021 Sep 24;JN-RM-2885-20. DOI: 10.1523/JNEUROSCI.2885-20.2021.
Amrita Benoy, Mohammad Zaki Bin Ibrahim, Thomas Behnisch, Sreedharan Sajikumar
Abstract
Hippocampal CA2, an inconspicuously positioned area between the well-studied CA1 and CA3 subfields, has captured research interest in recent years due to its role in social memory formation. However, the role of cholinergic inputs to the CA2 area for the regulation of synaptic plasticity remains to be fully understood. We show that cholinergic receptor activation with the non-selective cholinergic agonist, carbachol (CCh), triggers a protein synthesis-dependent and NMDAR-independent long-term synaptic depression (CCh-LTD) at entorhinal cortical (EC)-CA2 and Schaffer collateral (SC)-CA2 synapses in the hippocampus of adult male Wistar rats. The activation of muscarinic acetylcholine receptors (mAChRs) is critical for the induction of CCh-LTD with the results suggesting an involvement of M3 and M1 mAChRs in the early facilitation of CCh-LTD, while nicotinic acetylcholine receptor activation plays a role in the late maintenance of CCh-LTD at CA2 synapses. Remarkably, we find that CCh priming lowers the threshold for the subsequent induction of persistent long-term potentiation (LTP) of synaptic transmission at EC-CA2 and the plasticity-resistant SC-CA2 pathways. The effects of such a cholinergic-dependent synaptic depression on subsequent LTP at EC-CA2 and SC-CA2 synapses have not been previously explored. Collectively, the results demonstrate that CA2 synaptic learning rules are regulated in a metaplastic manner, whereby modifications triggered by prior cholinergic stimulation can dictate the outcome of future plasticity events. Moreover, the reinforcement of LTP at EC inputs to CA2 following the priming stimulus co-exists with concurrent sustained CCh-LTD at the SC-CA2 pathway and is dynamically scaled by modulation of SC-CA2 synaptic transmission.Significance Statement:The release of the neuromodulator acetylcholine is critically involved in processes of hippocampus-dependent memory formation. Cholinergic afferents originating in the medial septum and diagonal bands of Broca terminating in the hippocampal area CA2 might play an important role in the modulation of area-specific synaptic plasticity. Our findings demonstrate that cholinergic receptor activation induces a long-term depression of synaptic transmission at entorhinal cortical- and Schaffer collateral-CA2 synapses. This cholinergic activation-mediated long-term depression displays a bidirectional metaplastic switch to long-term potentiation on a future timescale. This suggests that such bidirectional synaptic modifications triggered by the dynamic modulation of tonic cholinergic receptor activation may support the formation of CA2-dependent memories given the increased hippocampal cholinergic tone during active wakefulness observed in exploratory behaviour.
Inactive variants of death receptor p75 NTR reduce Alzheimer’s neuropathology by interfering with APP internalization
EMBO J. 2021 Sep 1;40(17):e109067. doi: 10.15252/embj.2021109067.
Chenju Yi, Ket Yin Goh, Lik-Wei Wong, Ajeena Ramanujan, Kazuhiro Tanaka, Sreedharan Sajikumar, Carlos F Ibáñez
Abstract
NA
Decompartmentalisation as a simple color manipulation of plant-based marbling meat alternatives
Biomaterials. Volume 277, October 2021, 121107. DOI: 10.1016/j.biomaterials.2021.121107
Shujian Ong, Larry Loo, Marion Pang, Russell Tan, Yao Teng, Xuanming Lou, Sze Khen Chin, Mihir Yogesh Naik, Hanry Yu
Abstract
Recent efforts for cell-based meat cuts focus on engineering edible scaffolds, with visual cues which are key to enhancing consumer acceptance, receiving less attention Here, we employed artificial intelligence (AI)-based screening of potential plant materials and discovered that jackfruit (Artocarpus heterophyllus) has the natural structures to recapitulate marbling visuals of meat cuts. Plant tissue compositions are exploited for its differential polyphenol adsorption to produce complex marbling patterns. A one-step colour control method by varying oxidation and incubation conditions of polyphenols was developed to produce permanent meat-like colours resembling chicken, pork, and beef. The scaffold exhibits a meat-like browning behaviour when cooked and is shown to support high-density porcine myoblasts culture without masking the marbled appearance. Surveys with 78 volunteers found that marbled jackfruit scaffolds improved consumer perception of cell-based meat by ∼8%. Our approach of combining AI, tissue engineering, and sensory science unlocks the possibility of creating a range of novel cell-based meat cuts with consumer focus.
AIM2 inflammasome mediates apoptotic and pyroptotic death in the cerebellum following chronic hypoperfusion
Experimental Neurology, 30 Aug 2021, 346:113856. DOI: 10.1016/j.expneurol.2021.113856
Poh L, Razak SMBA, Lim HM, Lai MKP, Chen CL, Lim LHK, Arumugam TV, Fann DY
Abstract
Vascular dementia (VaD) is the second most common form of dementia and is caused by vascular pathologies resulting in chronic cerebral hypoperfusion (CCH)- induced brain injury, and ultimately cognitive impairment and memory loss. Several lines of evidence have demonstrated chronic inflammation may be involved in VaD disease progression. It is now recognized that a major contributor to cerebral and systemic chronic inflammation involves the activation of innate immune molecular complexes termed inflammasomes. Whilst previous studies on animal models of VaD have focused on the cortex, hippocampus and striatum, few studies have investigated the effect of CCH on the cerebellum. Emerging studies have found new roles of the cerebellum in cognition, based on its structural interconnectivity with other brain regions and clinical relevance in neuropsychological deficits. In the present study, we conducted our investigation on the cerebellum using a CCH mouse model of VaD following bilateral common carotid artery stenosis (BCAS). This study is the first to characterize an increased expression of inflammasome receptors, adaptor and effector proteins, markers of inflammasome activation, proinflammatory cytokines, and apoptotic and pyroptotic cell death proteins in the cerebellum following CCH. Furthermore, in AIM2 knockout mice, we observed attenuated inflammasome-mediated production of proinflammatory cytokines, apoptosis, and pyroptosis in the cerebellum following CCH. Collectively, our findings provide novel evidence that AIM2 inflammasome activation promotes apoptosis and pyroptosis in the cerebellum following chronic hypoperfusion in a mouse model of VaD.
Modulation of Septo-Hippocampal Neural Responses in Anesthetized and Behaving Rats by Septal AMPA Receptor Mechanisms
Front Neural Circuits. 2021 Jun 4;15:663633. doi: 10.3389/fncir.2021.663633.
Khairunisa Mohamad Ibrahim, Mohammed Zacky Ariffin, Sanjay Khanna
Abstract
This study explored the effects of septal glutamatergic transmission on septal-hippocampal theta activity via intraseptal microinjection of antagonist at AMPA receptors (AMPAR). The current results showed that microinjection of AMPAR antagonist, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione, 20 μg/μl, 0.5 μl), evoked a decrease in the frequency of theta activity evoked by various means in anesthetized and behaving rat. Theta wave activity was induced on: (a) intraseptal microinjection of carbachol, an agonist at cholinergic receptors, (b) reticular stimulation, (c) exploration in novel open field (OF), and (d) hind paw (HP) injection of the algogen, formalin. The effect on frequency in the formalin test was observed in an early period on injection of formalin, which was novel to the animal, but not in the later more sustained phase of the formalin test. The effect of NBQX, being seen in both anesthetized and behaving animals, suggests that the modulation of theta wave frequency, including in novelty, is a function of AMPAR in MS. The effect of the antagonist on theta power was less apparent, being observed only in anesthetized animals. In addition to theta power and frequency, intraseptal NBQX also attenuated suppression of CA1 population spike (PS) induced by intraseptal carbachol, thus suggesting that septal glutamate neurotransmission is involved in the spectrum of MS-mediated network responses. Indeed, in the context of behavior, formalin injection induced an increase in the level of septal glutamate, while NBQX attenuated nociceptive behaviors. Notably, MS is involved in the modulation of formalin nociception. These findings suggest that AMPA receptors are a key modulator of septal physiological function.
Assessment of the economic impact of heat-related labor productivity loss: a systematic review
Climatic Change. Volume 167, Article number: 22 (2021). DOI: 10.1007/s10584-021-03160-7.
Mengzhen Zhao, Jason Kai Wei Lee, Tord Kjellstrom & Wenjia Cai
Abstract
Heat stress caused by climate change and heat-related labor productivity losses have become global concerns. Estimating the economic impacts of heat stress is of great significance for employers, as well as sectoral and national policy makers who are searching for solutions to reduce productivity losses. As the value of economic impacts are sensitive to the research methodologies, we conducted a systematic review of published literature on the methodologies and results of economic impacts of heat on labor productivity. Four methods were summarized: the human capital (HC) method, the econometric method (EM), the input–output (IO) method, and the computable general equilibrium (CGE) model. Considering adaptation measures, global economic losses due to heat-related labor productivity losses are projected to range from 0.31% (0.14–0.5%, RCP2.6) to 2.6% (1.4–4%, RCP8.5) of global GDP in 2100. The published studies found that large economic losses occurred mainly in South and Southeast Asia, Sub-Saharan Africa, and Central America. Owing to different methodologies and considerations of adaptation measures, the disparities of results within the same area at a given time can be as high as 7.4-fold. We summarized the knowledge gaps in existing studies and proposed new directions to provide more targeted and reliable results for policy makers.
Perceptions of heat-health impacts and the effects of knowledge and preventive actions by outdoor workers in Hanoi, Vietnam
S. Lohrey, M. Chua, C. Gros, J. Faucet, J.K.W. Lee
Abstract
Extreme heat is an increasing climate threat, most pronounced in urban areas where poor populations are at particular risk. We analyzed heat impacts and vulnerabilities of 1027 outdoor workers who participated in a KAP survey in Hanoi, Vietnam in 2018, and the influence of their mitigation actions, their knowledge of heat-risks, and access to early warnings.
We grouped respondents by their main income (vendors, builders, shippers, others, multiple jobs, and non-working) and analyzed their reported heat-health impacts, taking into consideration socioeconomics, knowledge of heat impacts and preventive measures, actions taken, access to air-conditioning, drinking amounts and use of weather forecasts. We applied linear and logistic regression analyses using R.
Construction workers were younger and had less knowledge of heat-health impacts, but also reported fewer symptoms. Older females were more likely to report symptoms and visit a doctor. Access to air-conditioning in the bedroom depended on age and house ownership, but did not influence heat impacts as cooling was too expensive. Respondents who knew more heat exhaustion symptoms were more likely to report impacts (p < 0.01) or consult a doctor (p < 0.05). Similarly, those who checked weather updates were more likely to report heat impacts (p < 0.01) and experienced about 0.6 more symptoms (p < 0.01). Even though occupation type did not explain heat illness, builders knew considerably less (40%; p < 0.05) about heat than other groups but were twice as likely to consult a doctor than street vendors (p < 0.01). Knowledge of preventive actions and taking these actions both correlated positively with reporting of heat-health symptoms, while drinking water did not reduce these symptoms (p < 0.01). Child carers and homeowners experienced income losses in heatwaves (p < 0.01).
The differences support directed actions, such as dissemination of educational materials and weather forecasts for construction workers. The Red Cross assisted all groups with cooling tents, provision of drinks and health advice.
Changes in energy balance, body composition, metabolic profile and physical performance in a 62-day Army Ranger training in a hot-humid environment
Linda S.H. Gan, Priscilla W.P. Fan, Junren Zhang, Heinrich W. Nolte, Karl E. Friedl, Bradley C. Nindl, Jason K.W. Lee
Abstract
Objectives
To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment.
Design
Prospective cohort design.
Methods
Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase.
Results
Seventeen male participants (age: 24.5 ± 3.2 years, height: 173.9 ± 5.1 cm, body mass: 69.3 ± 3.2 kg, BMI: 22.9 ± 0.9 kg/m2, percent body fat: 14 ± 5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course.
Conclusions
Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts.
B7-H7 Is Inducible on T Cells to Regulate Their Immune Response and Serves as a Marker for Exhaustion
Front Immunol. 2021 Jun 1;12:682627. doi: 10.3389/fimmu.2021.682627. eCollection 2021.
Khang Luu, Herbert Schwarz, Andreas Lundqvist
Abstract
The discovery of immune checkpoints highlights the complexity of T cell signalling during an immune response. Upon activation, T cells express several molecules to regulate their function and to prevent overactivation. B7 homolog 7 (B7-H7) is expressed in tumours and associated with a worse prognosis. However, conflicting data regarding its function suggest that it can be both stimulatory and inhibitory. In this study we report that B7-H7 is also expressed on T cells upon cross-linking of CD3 and CD28 and that additional stimulation via CD137 further enhances the expression of B7-H7. B7-H7 is preferentially expressed on exhausted Th1 and Tc1 cells with an impaired secretion of TNF-α and IFN-γ. Blockade of B7-H7 with its natural receptor, recombinant CD28H, enhances T cell proliferation and activation. Thus, B7-H7 represents another target for immunotherapy and a biomarker to select for active effector T cells with relevance for adoptive cell transfer therapy.
DUSP16 promotes cancer chemoresistance through regulation of mitochondria-mediated cell death
Nat Commun. 2021 Apr 16;12(1):2284. doi: 10.1038/s41467-021-22638-7.
Heng Boon Low, Zhen Lim Wong, Bangyuan Wu, Li Ren Kong, Chin Wen Png, Yik-Lam Cho, Chun-Wei Li, Fengchun Xiao, Xuan Xin, Henry Yang, Jia Min Loo, Fiona Yi Xin Lee, Iain Bee Huat Tan, Ramanuj DasGupta , Han-Ming Shen, Herbert Schwarz, Nicholas R J Gascoigne, Boon Cher Goh, Xiaohong Xu, Yongliang Zhang
Abstract
Drug resistance is a major obstacle to the treatment of most human tumors. In this study, we find that dual-specificity phosphatase 16 (DUSP16) regulates resistance to chemotherapy in nasopharyngeal carcinoma, colorectal cancer, gastric and breast cancer. Cancer cells expressing higher DUSP16 are intrinsically more resistant to chemotherapy-induced cell death than cells with lower DUSP16 expression. Overexpression of DUSP16 in cancer cells leads to increased resistance to cell death upon chemotherapy treatment. In contrast, knockdown of DUSP16 in cancer cells increases their sensitivity to treatment. Mechanistically, DUSP16 inhibits JNK and p38 activation, thereby reducing BAX accumulation in mitochondria to reduce apoptosis. Analysis of patient survival in head & neck cancer and breast cancer patient cohorts supports DUSP16 as a marker for sensitivity to chemotherapy and therapeutic outcome. This study therefore identifies DUSP16 as a prognostic marker for the efficacy of chemotherapy, and as a therapeutic target for overcoming chemoresistance in cancer.
Artificial intelligence−enhanced white-light colonoscopy with attention guidance predicts colorectal cancer invasion depth
Gastrointestinal Endoscopy; September 2021; 94(3): 627-638.e1. doi: 10.1016/j.gie.2021.03.936.
Xiaobei Luo, Jiahao Wang, Zelong Han, Yang Yu, Zhenyu Chen, Feiyang Huang, Yumeng Xu, Jianqun Cai, Qiang Zhang, Weiguang Qiao, Inn Chuan Ng, Robby T. Tan, Side Liu, Hanry Yu
Abstract
Background and Aims
Endoscopic submucosal dissection (ESD) and EMR are applied in treating superficial colorectal neoplasms but are contraindicated by deeply invasive colorectal cancer (CRC). The invasion depth of neoplasms can be examined by an automated artificial intelligence (AI) system to determine the applicability of ESD and EMR.
Methods
A deep convolutional neural network with a tumor localization branch to guide invasion depth classification was constructed on the GoogLeNet architecture. The model was trained using 7734 nonmagnified white-light colonoscopy (WLC) images supplemented by image augmentation from 657 lesions labeled with histopathologic analysis of invasion depth. An independent testing dataset consisting of 1634 WLC images from 156 lesions was used to validate the model.
Results
For predicting noninvasive and superficially invasive neoplasms, the model achieved an overall accuracy of 91.1% (95% confidence interval [CI], 89.6%-92.4%), with 91.2% sensitivity (95% CI, 88.8%-93.3%) and 91.0% specificity (95% CI, 89.0%-92.7%) at an optimal cutoff of .41 and the area under the receiver operating characteristic (AUROC) curve of .970 (95% CI, .962-.978). Inclusion of the advanced CRC data significantly increased the sensitivity in differentiating superficial neoplasms from deeply invasive early CRC to 65.3% (95% CI, 61.9%-68.8%) with an AUROC curve of .729 (95% CI, .699-.759), similar to experienced endoscopists (.691; 95% CI, .624-.758).
Conclusions
We have developed an AI-enhanced attention-guided WLC system that differentiates noninvasive or superficially submucosal invasive neoplasms from deeply invasive CRC with high accuracy, sensitivity, and specificity.
Reproducibility and robustness of high-throughput S1500+ transcriptomics on primary rat hepatocytes for chemical-induced hepatotoxicity assessment
Current Research in Toxicology. 2: 282-295. doi: 10.1016/j.crtox.2021.07.003.
Fan Lee, Imran Shah, Yun Ting Soong, Jiangwa Xing, Inn Chuan Ng, Farah Tasnim, Hanry Yu
Abstract
Cell-based in vitro models coupled with high-throughput transcriptomics (HTTr) are increasingly utilized as alternative methods to animal-based toxicity testing. Here, using a panel of 14 chemicals with different risks of human drug-induced liver injury (DILI) and two dosing concentrations, we evaluated an HTTr platform comprised of collagen sandwich primary rat hepatocyte culture and the TempO-Seq surrogate S1500+ (ST) assay. First, the HTTr platform was found to exhibit high reproducibility between technical and biological replicates (r greater than 0.85). Connectivity mapping analysis further demonstrated a high level of inter-platform reproducibility between TempO-Seq data and Affymetrix GeneChip data from the Open TG-GATES project. Second, the TempO-Seq ST assay was shown to be a robust surrogate to the whole transcriptome (WT) assay in capturing chemical-induced changes in gene expression, as evident from correlation analysis, PCA and unsupervised hierarchical clustering. Gene set enrichment analysis (GSEA) using the Hallmark gene set collection also demonstrated consistency in enrichment scores between ST and WT assays. Lastly, unsupervised hierarchical clustering of hallmark enrichment scores broadly divided the samples into hepatotoxic, intermediate, and non-hepatotoxic groups. Xenobiotic metabolism, bile acid metabolism, apoptosis, p53 pathway, and coagulation were found to be the key hallmarks driving the clustering. Taken together, our results established the reproducibility and performance of collagen sandwich culture in combination with TempO-Seq S1500+ assay, and demonstrated the utility of GSEA using the hallmark gene set collection to identify potential hepatotoxicants for further validation.
A chemical biology approach reveals a dependency of glioblastoma on biotin distribution
Science Advances, 3 Sep 2021; 7(36). DOI: 10.1126/sciadv.abf6033
Jeehyun Yoon, Oleg V. Grinchuk, Srinivasaraghavan Kannan, Melgious Jin Yan Ang, Zhenglin Li, Emmy Xue Yun Tay, Ker Zhing Lok, Bernice Woon Li Lee, You Heng Chuah, Kimberly Chia, Roberto Tirado Magallanes, Chenfei Liu, Haonan Zhao, Jin Hui Hor, Jhin Jieh Lim, Touati Benoukraf, Tan Boon Toh, Edward Kai-Hua Chow, Jean-Paul Kovalik, Jianhong Ching, Shi-Yan Ng, Ming Joo Koh, Xiaogang Liu, Chandra Shekhar Verma, and Derrick Sek Tong Ong
Abstract
Glioblastoma (GBM) is a uniformly lethal disease driven by glioma stem cells (GSCs). Here, we use a chemical biology approach to unveil previously unknown GBM dependencies. By studying sulconazole (SN) with anti-GSC properties, we find that SN disrupts biotin distribution to the carboxylases and histones. Transcriptomic and metabolomic analyses of SN-treated GSCs reveal metabolic alterations that are characteristic of biotin-deficient cells, including intracellular cholesterol depletion, impairment of oxidative phosphorylation, and energetic crisis. Furthermore, SN treatment reduces histone biotinylation, histone acetylation, and expression of superenhancer-associated GSC critical genes, which are also observed when biotin distribution is genetically disrupted by holocarboxylase synthetase (HLCS) depletion. HLCS silencing impaired GSC tumorigenicity in an orthotopic xenograft brain tumor model. In GBM, high HLCS expression robustly indicates a poor prognosis. Thus, the dependency of GBM on biotin distribution suggests that the rational cotargeting of biotin-dependent metabolism and epigenetic pathways may be explored for GSC eradication.
Long-term plasticity in the hippocampus: maintaining within and ‘tagging’ between synapses
FEBS J. 2021 Jun 10. doi: 10.1111/febs.16065. Online ahead of print.
Mohammad Zaki Bin Ibrahim, Amrita Benoy, Sreedharan Sajikumar
Abstract
Synapses between neurons are malleable biochemical structures, strengthening and diminishing over time dependent on the type of information they receive. This phenomenon known as synaptic plasticity underlies learning and memory, and its different forms, long-term potentiation (LTP) and long-term depression (LTD), perform varied cognitive roles in reinforcement, relearning and associating memories. Moreover, both LTP and LTD can exist in an early transient form (early-LTP/LTD) or a late persistent form (late-LTP/LTD), which are triggered by different induction protocols, and also differ in their dependence on protein synthesis and the involvement of key molecular players. Beyond homosynaptic modifications, synapses can also interact with one another. This is encapsulated in the synaptic tagging and capture hypothesis (STC), where synapses expressing early-LTP/LTD present a ‘tag’ that can capture the protein synthesis products generated during a temporally proximal late-LTP/LTD induction. This ‘tagging’ phenomenon forms the framework of synaptic interactions in various conditions and accounts for the cellular basis of the time-dependent associativity of short-lasting and long-lasting memories. All these synaptic modifications take place under controlled neuronal conditions, regulated by subcellular elements such as epigenetic regulation, proteasomal degradation and neuromodulatory signals. Here, we review current understanding of the different forms of synaptic plasticity and its regulatory mechanisms in the hippocampus, a brain region critical for memory formation. We also discuss expression of plasticity in hippocampal CA2 area, a long-overlooked narrow hippocampal subfield and the behavioural correlate of STC. Lastly, we put forth perspectives for an integrated view of memory representation in synapses.
Inhibition of lysine methyltransferase G9a/GLP reinstates long-term synaptic plasticity and synaptic tagging/capture by facilitating protein synthesis in the hippocampal CA1 area of APP/PS1 mouse model of Alzheimer’s disease
Transl Neurodegener. 2021 Jun 29;10(1):23.
doi: 10.1186/s40035-021-00247-0.
Javan Lee Tze Ha, Karen Ka Lam Pang, Sheila Rui Xia Ang, Mahima Sharma, Sreedharan Sajikumar
Abstract
no astract available
Targeting novel human transient receptor potential ankyrin 1 splice variation with splice-switching antisense oligonucleotides
PAIN: July 2021 – Volume 162 – Issue 7 – p 2097-2109. DOI: 10.1097/j.pain.0000000000002216
Huang, Hua; Tay, Shermaine Huiping; Ng, Winanto; Ng, Shi Yan; Soong, Tuck Wah
Abstract
Activation of transient receptor potential ankyrin 1 (TRPA1) channels by both environmental irritants and endogenous inflammatory mediators leads to excitation of the nerve endings, resulting in acute sensation of pain, itch, or chronic neurogenic inflammation. As such, TRPA1 channels are actively pursued as therapeutic targets for various pathological nociception and pain disorders. We uncovered that exon 27 of human TRPA1 (hTRPA1) could be alternatively spliced into hTRPA1_27A and hTRPA1_27B splice variants. The resulting channel variants displayed reduced expression, weakened affinity to interact with WT, and suffered from complete loss of function because of disruption of the C-terminal coiled-coil domain. Using a human minigene construct, we revealed that binding of splicing factor serine/arginine-rich splicing factor 1 (SRSF1) to the exonic splicing enhancer was critical for the inclusion of intact exon 27. Knockdown of SRSF1, mutation within exonic splicing enhancer, or masking SRSF1 binding with antisense oligonucleotides promoted alternative splicing within exon 27. Finally, antisense oligonucleotides-induced alternative splicing produced transcript and protein variants that could be functionally determined as diminished endogenous TRPA1 activity in human Schwann cell-line SNF96.2 and hiPSCs-derived sensory neurons. The outcome of the work could potentially offer a novel therapeutic strategy for treating pain by targeting alternative splicing of hTRPA1.
Modulation of septo-hippocampal neural responses in anesthetized and behaving rats by septal AMPA receptor mechanisms
Frontiers in Neural Circuits, 04 Jun 2021, 15:663633. DOI: 10.3389/fncir.2021.663633
Ibrahim KM, Ariffin MZ, Khanna S
Abstract
This study explored the effects of septal glutamatergic transmission on septal-hippocampal theta activity via intraseptal microinjection of antagonist at AMPA receptors (AMPAR). The current results showed that microinjection of AMPAR antagonist, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione, 20 μg/μl, 0.5 μl), evoked a decrease in the frequency of theta activity evoked by various means in anesthetized and behaving rat. Theta wave activity was induced on: (a) intraseptal microinjection of carbachol, an agonist at cholinergic receptors, (b) reticular stimulation, (c) exploration in novel open field (OF), and (d) hind paw (HP) injection of the algogen, formalin. The effect on frequency in the formalin test was observed in an early period on injection of formalin, which was novel to the animal, but not in the later more sustained phase of the formalin test. The effect of NBQX, being seen in both anesthetized and behaving animals, suggests that the modulation of theta wave frequency, including in novelty, is a function of AMPAR in MS. The effect of the antagonist on theta power was less apparent, being observed only in anesthetized animals. In addition to theta power and frequency, intraseptal NBQX also attenuated suppression of CA1 population spike (PS) induced by intraseptal carbachol, thus suggesting that septal glutamate neurotransmission is involved in the spectrum of MS-mediated network responses. Indeed, in the context of behavior, formalin injection induced an increase in the level of septal glutamate, while NBQX attenuated nociceptive behaviors. Notably, MS is involved in the modulation of formalin nociception. These findings suggest that AMPA receptors are a key modulator of septal physiological function.
Establishing intensifying chronic exposure to extreme heat as a slow onset event with implications for health, wellbeing, productivity, society and economy
Elspeth Oppermann, Tord Kjellstrom, Bruno Lemke, Matthias Otto, Jason Kai Wei Lee
Abstract
The Warsaw International Mechanism for Loss and Damage has identified increasing temperatures as a key slow onset event. However, it is the resulting increases in short-term heat events — heatwaves — that have so far been the primary focus of risk assessment and policy, while gradual and sustained increases in temperature have received less attention. This is a global issue but particularly important in tropical and subtropical regions already chronically exposed to extreme heat. This paper reviews recent analyses of intensifying seasonal and year-round extreme heat exposures and how this affects daily life, including worker productivity, health and wellbeing, reduced GDP and economic viability. It frames this as a slow onset event and closes with a brief indication of tools available to assess and address these risks.
The Impact of Temperature on the Risk of COVID-19: A Multinational Study
Int. J. Environ. Res. Public Health 2021, 18(8), 4052. DOI: 10.3390/ijerph18084052.
Hsiao-Yu Yang and Jason Kai Wei Lee
Abstract
The current understanding of ambient temperature and its link to the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The objective of this study was to explore the environmental and climatic risk factors for SARS-CoV-2. For this study, we analyzed the data at the beginning of the outbreak (from 20 January to 31 March 2020) to avoid the influence of preventive or control measures. We obtained the number of cases and deaths due to SARS-CoV-2, international tourism, population age, universal health coverage, regional factors, the SARS-CoV-2 testing rate, and population density of a country. A total of 154 countries were included in this study. There were high incidence rates and mortality risks in the countries that had an average ambient temperature between 0 and 10 °C. The adjusted incidence rate for temperatures between 0 and 10 °C was 2.91 (95% CI 2.87–2.95). We randomly divided the data into a training set (80% of data) for model derivation and a test set (20% of data) for validation. Using a random forest statistical model, the model had high accuracy for predicting the high epidemic status of a country (ROC = 95.5%, 95% CI 87.9–100.0%) in the test set. Population age, temperature, and international tourism were the most important factors affecting the risk of SARS-CoV-2 in a country. An understanding the determinants of the SARS-CoV-2 outbreak can help to design better strategies for disease control. This study highlights the need to consider thermal effect in the prevention of emerging infectious diseases.
Hydration Status, Fluid Intake, Sweat Rate, and Sweat Sodium Concentration in Recreational Tropical Native Runners
Nutrients 2021, 13(4), 1374. DOI: 10.3390/nu13041374.
Juthamard Surapongchai, Vitoon Saengsirisuwan, Ian Rollo, Rebecca K. Randell, Kanpiraya Nithitsuttibuta, Patarawadee Sainiyom, Clarence Hong Wei Leow and Jason Kai Wei Lee
Abstract
Aim: The purpose of this study was to evaluate hydration status, fluid intake, sweat rate, and sweat sodium concentration in recreational tropical native runners. Methods: A total of 102 males and 64 females participated in this study. Participants ran at their self-selected pace for 30–100 min. Age, environmental conditions, running profiles, sweat rates, and sweat sodium data were recorded. Differences in age, running duration, distance and pace, and physiological changes between sexes were analysed. A p-value cut-off of 0.05 depicted statistical significance. Results: Males had lower relative fluid intake (6 ± 6 vs. 8 ± 7 mL·kg−1·h−1, p < 0.05) and greater relative fluid balance deficit (−13 ± 8 mL·kg−1·h−1 vs. −8 ± 7 mL·kg−1·h−1, p < 0.05) than females. Males had higher whole-body sweat rates (1.3 ± 0.5 L·h−1 vs. 0.9 ± 0.3 L·h−1, p < 0.05) than females. Mean rates of sweat sodium loss (54 ± 27 vs. 39 ± 22 mmol·h−1) were higher in males than females (p < 0.05). Conclusions: The sweat profile and composition in tropical native runners are similar to reported values in the literature. The current fluid replacement guidelines pertaining to volume and electrolyte replacement are applicable to tropical native runners.
COVID-19 and heat waves: New challenges for healthcare systems
Environmental Research, Volume 198, July 2021, 111153. DOI: 10.1016/j.envres.2021.111153.
Stephan Bose-O’Reilly, Hein Daanen, Katharina Deering, Nicola Gerrett, Maud Maria Theresia Elisabeth Huynen, Jason Lee, Stefan Karrasch, Franziska Matthies-Wiesler, Hanna Mertes, Julia Schoierer, Joy Shumake-Guillemot, Petervan den Hazel, Joris Adriaan Frank van Loenhout, Dennis Nowak
Abstract
Heat waves and Covid-19 overlap, as this pandemic continues into summer 2021. Using a narrative review, we identified overlapping risk groups and propose coping strategies. The high-risk groups for heat-related health problems as well as for high-risk COVID-19 groups overlap considerably (elderly with pre-existing health conditions). Health care facilities will again be challenged by Covid-19 during heat waves. Health care personnel are also at risk of developing heat related health problems during hot periods due to the use of personal protective equipment to shield themselves from SARS-CoV-2 and must therefore be protected from excessive heat periods. Some existing recommendations for heat health protection contradict recommendations for COVID-19 protection. This paper provides a preliminary overview of possible strategies and interventions to tackle these ambiguities. The existing recommendations for protection against heat-related illnesses need revisions to determine whether they include essential aspects of infection control and occupational safety and how they may be supplemented.
A Web Survey to Evaluate the Thermal Stress Associated with Personal Protective Equipment among Healthcare Workers during the COVID-19 Pandemic in Italy
Int. J. Environ. Res. Public Health 2021, 18(8), 3861. DOI: 10.3390/ijerph18083861.
Alessandro Messeri, Michela Bonafede, Emma Pietrafesa, Iole Pinto, Francesca de’Donato, Alfonso Crisci, Jason Kai Wei Lee, Alessandro Marinaccio, Miriam Levi, Marco Morabito and on behalf of the WORKLIMATE Collaborative Group
Abstract
The pandemic has been afflicting the planet for over a year and from the occupational point of view, healthcare workers have recorded a substantial increase in working hours. The use of personal protective equipment (PPE), necessary to keep safe from COVID-19 increases the chances of overheating, especially during the summer seasons which, due to climate change, are becoming increasingly warm and prolonged. A web survey was carried out in Italy within the WORKLIMATE project during the summer and early autumn 2020. Analysis of variance (ANOVA) was used to evaluate differences between groups. 191 questionnaires were collected (hospital doctor 38.2%, nurses 33.5%, other healthcare professionals 28.3%). The impact of PPE on the thermal stress perception declared by the interviewees was very high on the body areas directly covered by these devices (78% of workers). Workers who used masks for more than 4 h per day perceived PPE as more uncomfortable (p < 0.001) compared to the others and reported a greater productivity loss (p < 0.001). Furthermore, the study highlighted a high perception of thermal stress among healthcare workers that worn COVID-19-PPE and this enhances the need for appropriate heat health warning systems and response measures addressed to the occupational sector.
Thermal strain and fluid balance during a 72-km military route march in a field setting
Singapore Med J 2021, 1–18. DOI: 10.11622/smedj.2021053.
Beng Hoong Poon, Suriya Prakaash, Ya Shi Teo, Priscilla Weiping Fan, Jason Kai Wei Lee
Abstract
Introduction: A physiological profiling study was done to evaluate thermal strain as well as fluid and electrolyte balances on heat-acclimatised men performing a 72-km route march in a field setting.
Methods: 38 male soldiers (age range 18–23 years) participated in the study,as part of a cohort that marched for 72 km, with loads for about 26 hours. Core temperature and heart rate sensors were used for the duration of the march. Fluid and food intake and output were monitored for the duration of the march. Blood samples were taken one day before the march (pre-march),immediately after the march before they had any opportunity to recover (Post 1) and on the 15thday after themarch to ascertain recovery (Post2) to assess fluid and electrolyte profiles.
Results: Mean core temperature was within safe limits, ranging from 37.1to 38.1°C throughout the march. There was an average overall decrease in serum sodium levels, a decline in serum sodium concentration in 28 participants and three instances of hyponatraemia (serum sodium concentration< 135 mmol/L).
Conclusion: Our study found low thermal strain among heat-acclimatised individuals during a 72-km route march. However, there was an average overall decrease in serum sodium levels,even when the participants were allowed to drink ad libitum. Challenges of exercise-associated hyponatraemia during prolonged activities remain to be addressed.
The redox-senescence axis and its therapeutic targeting
Redox Biology, Volume 45, September 2021, 102032. DOI: 10.1016/j.redox.2021.102032.
Natalie YL Ngoi, Angeline QX Liew, Stephen J.F. Chong, Matthew S. Davids, Marie-Veronique Clement, Shazib Pervaiz
Abstract
Significance
Cellular growth arrest, associated with ‘senescence’, helps to safeguard against the accumulation of DNA damage which is often recognized as the underlying mechanism of a wide variety of age-related pathologies including cancer. Cellular senescence has also been described as a ‘double-edged sword’. In cancer, for example, the creation of an immune-suppressive milieu by senescent tumor cells through the senescence-associated secretory phenotype contributes toward carcinogenesis and cancer progression.
Recent advances
The potential for cellular senescence to confer multi-faceted effects on tissue fate has led to a rejuvenated interest in its landscape and targeting. Interestingly, redox pathways have been described as both triggers and propagators of cellular senescence, leading to intricate cross-links between both pathways.
Critical issues
In this review, we describe the mechanisms driving cellular senescence, the interface with cellular redox metabolism as well as the role that chemotherapy-induced senescence plays in secondary carcinogenesis. Notably, the role that anti-apoptotic proteins of the Bcl-2 family play in inducing drug resistance via mechanisms that involve senescence induction.
Future directions
Though the therapeutic targeting of senescent cells as cancer therapy remains in its infancy, we summarize the current development of senotherapeutics, including recognized senotherapies, as well as the repurposing of drugs as senomorphic/senolytic candidates.
A Novel Balanced Chromosomal Translocation in an Azoospermic Male: A Case Report
J Reprod Infertil. Apr-Jun 2021;22(2):133-137. doi: 10.18502/jri.v22i2.5802.
Abhik Chakraborty, Indira Palo, Souvick Roy, Shu Wen Koh, Manoor Prakash Hande, Birendranath Banerjee
Abstract
Background: Balanced translocation and azoospermia as two main reasons for recurrent pregnancy loss are known to be the leading causes of infertility across the world. Balanced translocations in azoospermic males are very rare and extensive studies need to be performed to elucidate the translocation status of the affected individuals.
Case presentaion: The cytogenetic characterization of a 28 year old male and his female partner is reported in this study. The male partner was diagnosed with non-obstructive azoospermia (NOA) and the couple was unable to conceive. Cytogenetic analysis by karyotyping through Giemsa-trypsin-giemsa banding technique (GTG) showed a novel balanced translocation, 46,XY,t(19;22)(19q13.4;22q11.2), 13ps+ in the male and the female karyotype was found to be 46,XX. Multicolor fluorescence in situ hybridization (mFISH) analysis on paternal chromosomal preparations confirmed both the region and origin of balanced translocation. The status of Y chromosome microdeletion (YMD) was analyzed and no notable microdeletion was observed. Furthermore, protein-protein interaction (PPI) network analysis was performed for breakpoint regions to explore the possible functional genetic associations.
Conclusion: The azoospermic condition of the male patient along with novel balanced chromosomal translocation was responsible for infertility irrespective of its YMD status. Therefore, cytogenetic screening of azoospermic patients should be performed in addition to routine semen analysis to rule out or to confirm presence of any numerical or structural anomaly in the patient.
RENEB Inter-Laboratory comparison 2017: limits and pitfalls of ILCs
Int J Radiat Biol. 2021 May 25;1-18. doi: 10.1080/09553002.2021.1928782. Online ahead of print.
Eric Gregoire, Joan Francesc Barquinero, Gaetan Gruel, Mohamedamine Benadjaoud, Juan S Martinez, Christina Beinke, Adayabalam Balajee, Philip Beukes, William F Blakely, Inmaculada Dominguez, Pham Ngoc Duy, Octávia Monteiro Gil, Inci Güçlü, Kamile Guogyte, Savina Petrova Hadjidekova, Valeria Hadjidekova, Prakash Hande, Seongjae Jang, Katalin Lumniczky, Roberta Meschini, Mirta Milic, Alegria Montoro, Jayne Moquet, Mercedes Moreno, Farrah N Norton, Ursula Oestreicher, Jelena Pajic, Laure Sabatier, Sylwester Sommer, Antonella Testa, Georgia Terzoudi, Marco Valente, Perumal Venkatachalam, Anne Vral, Ruth C Wilkins, Andrzej Wojcik, Demetre Zafiropoulos, Ulrike Kulka
Abstract
Purpose: In case of a mass-casualty radiological event, there would be a need for networking to overcome surge limitations and to quickly obtain homogeneous results (reported aberration frequencies or estimated doses) among biodosimetry laboratories. These results must be consistent within such network. Inter-laboratory comparisons (ILCs) are widely accepted to achieve this homogeneity. At the European level, a great effort has been made to harmonize biological dosimetry laboratories, notably during the MULTIBIODOSE and RENEB projects. In order to continue the harmonization efforts, the RENEB consortium launched this intercomparison which is larger than the RENEB network, as it involves 38 laboratories from 21 countries. In this ILC all steps of the process were monitored, from blood shipment to dose estimation. This exercise also aimed to evaluate the statistical tools used to compare laboratory performance.
Materials and methods: Blood samples were irradiated at three different doses, 1.8, 0.4 and 0 Gy (samples A, C and B) with 4-MV X-rays at 0.5 Gy min-1, and sent to the participant laboratories. Each laboratory was requested to blindly analyze 500 cells per sample and to report the observed frequency of dicentric chromosomes per metaphase and the corresponding estimated dose.
Results: This ILC demonstrates that blood samples can be successfully distributed among laboratories worldwide to perform biological dosimetry in case of a mass casualty event. Having achieved a substantial harmonization in multiple areas among the RENEB laboratories issues were identified with the available statistical tools, which are not capable to advantageously exploit the richness of results of a large ILCs. Even though Z- and U-tests are accepted methods for biodosimetry ILCs, setting the number of analyzed metaphases to 500 and establishing a tests’ common threshold for all studied doses is inappropriate for evaluating laboratory performance. Another problem highlighted by this ILC is the issue of the dose-effect curve diversity. It clearly appears that, despite the initial advantage of including the scoring specificities of each laboratory, the lack of defined criteria for assessing the robustness of each laboratory’s curve is a disadvantage for the ‘one curve per laboratory’ model.
Conclusions: Based on our study, it seems relevant to develop tools better adapted to the collection and processing of results produced by the participant laboratories. We are confident that, after an initial harmonization phase reached by the RENEB laboratories, a new step toward a better optimization of the laboratory networks in biological dosimetry and associated ILC is on the way.
Investigations on the new mechanism of action for acetaldehyde-induced clastogenic effects in human lung fibroblasts
Varsha Hande, Keith Teo, Prarthana Srikanth, Jane See Mei Wong, Swaminathan Sethu, Wilner Martinez- Lopez, Manoor Prakash Hande
Abstract
Acetaldehyde (AA) has been classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC, WHO) and by the US Environmental Protection Agency due to its ability to cause tumours following inhalation or alcohol consumption in animals. Humans are constantly exposed to AA through inhalation from the environment through cigarette smoke, vehicle fumes and industrial emissions as well as by persistent alcohol ingestion. Individuals with deficiencies in the enzymes that are involved in the metabolism of AA are more susceptible to its toxicity and constitute a vulnerable human population. Studies have shown that AA induces DNA damage and cytogenetic abnormalities. A study was undertaken to elucidate the clastogenic effects induced by AA and any preceding DNA damage that occurs in normal human lung fibroblasts as this will further validate the detrimental effects of inhalation exposure to AA. AA exposure induced DNA damage, involving DNA double strand breaks, which could possibly occur at the telomeric regions as well, resulting in a clastogenic effect and subsequent genomic instability, which contributed to the cell cycle arrest. The clastogenic effect induced by AA in human lung fibroblasts was evidenced by micronuclei induction and chromosomal aberrations, including those at the telomeric regions. Co-localisation between the DNA double strand breaks and telomeric regions was observed, suggesting possible induction of DNA double strand breaks due to AA exposure at the telomeric regions as a new mechanism beyond the clastogenic effect of AA. From the cell cycle profile following AA exposure, a G2/M phase arrest and a decrease in cell viability were also detected. Therefore, these effects due to AA exposure via inhalation may have implications in the development of carcinogenesis in humans.
Prediction of the Acute or Late Radiation Toxicity Effects in Radiotherapy Patients Using Ex Vivo Induced Biodosimetric Markers: A Review
Journal of Personalized Medicine, Volume 10, Issue 4. DOI: 10.3390/jpm10040285
Volodymyr Vinnikov, Manoor Prakash Hande, Ruth Wilkins, Andrzej Wojcik, Eduardo Zubizarreta and Oleg Belyakov
Abstract
A search for effective methods for the assessment of patients’ individual response to radiation is one of the important tasks of clinical radiobiology. This review summarizes available data on the use of ex vivo cytogenetic markers, typically used for biodosimetry, for the prediction of individual clinical radiosensitivity (normal tissue toxicity, NTT) in cells of cancer patients undergoing therapeutic irradiation. In approximately 50% of the relevant reports, selected for the analysis in peer-reviewed international journals, the average ex vivo induced yield of these biodosimetric markers was higher in patients with severe reactions than in patients with a lower grade of NTT. Also, a significant correlation was sometimes found between the biodosimetric marker yield and the severity of acute or late NTT reactions at an individual level, but this observation was not unequivocally proven. A similar controversy of published results was found regarding the attempts to apply G2- and γH2AX foci assays for NTT prediction. A correlation between ex vivo cytogenetic biomarker yields and NTT occurred most frequently when chromosome aberrations (not micronuclei) were measured in lymphocytes (not fibroblasts) irradiated to relatively high doses (4–6 Gy, not 2 Gy) in patients with various grades of late (not early) radiotherapy (RT) morbidity. The limitations of existing approaches are discussed, and recommendations on the improvement of the ex vivo cytogenetic testing for NTT prediction are provided. However, the efficiency of these methods still needs to be validated in properly organized clinical trials involving large and verified patient cohorts.
High glucose alters the DNA methylation pattern of neurodevelopment associated genes in human neural progenitor cells in vitro
Scientific Reports volume 10, Article number: 15676 (2020). DOI: 10.1038/s41598-020-72485-7
Deepika Kandilya, Sukanya Shyamasundar, Dhiraj Kumar Singh, Avijit Banik, Manoor Prakash Hande, Walter Stünkel, Yap Seng Chong & S. Thameem Dheen
Abstract
Maternal diabetes alters the global epigenetic mechanisms and expression of genes involved in neural tube development in mouse embryos. Since DNA methylation is a critical epigenetic mechanism that regulates gene functions, gene-specific DNA methylation alterations were estimated in human neural progenitor cells (hNPCs) exposed to high glucose (HG) in the present study. The DNA methylation pattern of genes involved in several signalling pathways including axon guidance (SLIT1-ROBO2 pathway), and Hippo pathway (YAP and TAZ) was altered in hNPCs exposed to HG. The expression levels of SLIT1-ROBO2 pathways genes (including its effectors, SRGAP1 and CDC42) which mediates diverse cellular processes such as proliferation, neurogenesis and axon guidance, and Hippo pathway genes (YAP and TAZ) which regulates proliferation, stemness, differentiation and organ size were downregulated in hNPCs exposed to HG. A recent report suggests a possible cross-talk between SLIT1-ROBO2 and TAZ via CDC42, a mediator of actin dynamics. Consistent with this, SLIT1 knockdown downregulated the expression of its effectors and TAZ in hNPCs, suggesting that HG perturbs the cross-talk between SLIT1-ROBO2 and TAZ in hNPCs. Overall, this study demonstrates that HG epigenetically alters the SLIT1-ROBO2 and Hippo signalling pathways in hNPCs, forming the basis for neurodevelopmental disorders in offspring of diabetic pregnancy.
Recent Advances in Models of Immune-Mediated Drug-Induced Liver Injury
Frontiers in Toxicology, 21 April 2021; 3: 6053892. doi: 10.3389/ftox.2021.605392.
Farah Tasnim, Xiaozhong Huang, Christopher Zhe Wei Lee, Florent Ginhoux and Hanry Yu
Abstract
Hepatic inflammation is a key feature of a variety of liver diseases including drug-induced liver injury (DILI), orchestrated by the innate immune response (Kupffer cells, monocytes, neutrophils, dendritic cells) and the adaptive immune system (T cells and natural killer T cells). In contrast to acute DILI, prediction of immune-mediated DILI (im-DILI) has been more challenging due to complex disease pathogenesis, lack of reliable models and limited knowledge of underlying mechanisms. This review summarizes in vivo and in vitro systems that have been used to model im-DILI. In particular, the review focuses on state-of-the-art in vitro human-based multicellular models which have been developed to supplement the use of in vivo models due to interspecies variation and increasing ethical concerns regarding animal use. Advantages of the co-cultures in maintaining hepatocyte functions and importantly, introducing heterotypic cell-cell interactions to mimic inflammatory hepatic microenvironment are discussed. Challenges regarding cell source and incorporation of different cells with physical cell-cell contact are outlined and potential solutions are proposed. It is likely that better understanding of the interplay of immune cells in liver models will allow for the development of more accurate systems to better predict hepatotoxicity and stratification of drugs that can cause immune-mediated effects.
Design and Fabrication of the Vertical-Flow Bioreactor for Compaction Hepatocyte Culture in Drug Testing Application
Biosensors-Basel, May 2021; 11(5): 160. doi: 10.3390/bios11050160.
Liang Zhu, Zhenfeng Wang, Huanming Xia, and Hanry Yu
Abstract
The perfusion culture of primary hepatocytes has been widely adopted to build bioreactors for various applications. As a drug testing platform, a unique vertical-flow bioreactor (VfB) array was found to create the compaction culture of hepatocytes which mimicked the mechanic microenvironment in vivo while maintaining the 3D cell morphology in a 2D culture setup and enhancing the hepatic functions for a sustained culture. Here, we report the methodology in designing and fabricating the VfB to reach ideal bioreactor requirements, optimizing the VfB as a prototype for drug testing, and to demonstrate the enhanced hepatic function so as to demonstrate the performance of the bioreactor. This device enables the modular, scalable, and manufacturable construction of a functional drug testing platform through the sustained maintenance of model cells.
A Scalable and Sensitive Steatosis Chip with Long-Term Perfusion of in situ Differentiated HepaRG Organoids
Biomaterials. Available online 1 June 2021, 120904. doi: 10.1016/j.biomaterials.2021.120904.
Yao Teng, Zixuan Zhao, Farah Tasnim, Xiaozhong Huang, HanryYu
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a significant liver disease without approved therapy, lacking human NAFLD models to aid drug development. Existing models are either under-performing or too complex to allow robust drug screening. Here we have developed a 100-well drug testing platform with improved HepaRG organoids formed with uniform size distribution, and differentiated in situ in a perfusion microfluidic device, SteatoChip, to recapitulate major NAFLD features. Compared with the pre-differentiated spheroids, the in situ differentiated HepaRG organoids with perfusion experience well-controlled chemical and mechanical microenvironment, and 3D cellular niche, to exhibit enhanced hepatic differentiation (albumin+ cells ratio: 66.2% in situ perfusion vs 46.1% pre-differentiation), enriched and uniform hepatocyte distribution in organoids, higher level of hepatocyte functions (5.2 folds in albumin secretion and 7.6 folds in urea synthesis), enhanced cell polarity and bile canaliculi structures. When induced with free fatty acid (FFA), cells exhibit significantly higher level of lipid accumulation (6.6 folds for in situ perfusion vs 4.4 folds for pre-differentiation), altered glucose regulation and reduced Akt phosphorylation in the organoids. SteatoChip detects reduction of steatosis when cells are incubated with three different anti-steatosis compounds, 78.5% by metformin hydrochloride, 71.3% by pioglitazone hydrochloride and 66.6% by obeticholic acid, versus the control FFA-free media (38% reduction). The precision microenvironment control in SteatoChip enables improved formation, differentiation, and function of HepaRG organoids to serve as a scalable and sensitive drug testing platform, to potentially accelerate the NAFLD drug development.
Digital CRISPR-based method for the rapid detection and absolute quantification of nucleic acids
Biomaterials. Volume 274, July 2021, 120876. doi: 10.1016/j.biomaterials.2021.120876.
Xiaolin Wu, Joshua K. Tay, Chuan Keng Goh, Cheryl Chan, Yie Hou Lee, Stacy L. Springs, De Yun Wang, Kwok Seng Loh, Timothy K. Lu, Hanry Yu
Abstract
Rapid diagnostics of adventitious agents in biopharmaceutical/cell manufacturing release testing and the fight against viral infection have become critical. Quantitative real-time PCR and CRISPR-based methods rapidly detect DNA/RNA in 1 h but suffer from inter-site variability. Absolute quantification of DNA/RNA by methods such as digital PCR reduce this variability but are currently too slow for wider application. Here, we report a RApid DIgital Crispr Approach (RADICA) for absolute quantification of nucleic acids in 40-60 min. Using SARS-CoV-2 as a proof-of-concept target, RADICA allows for absolute quantification with a linear dynamic range of 0.6–2027 copies/μL (R2 value > 0.99), high accuracy and low variability, no cross-reactivity to similar targets, and high tolerance to human background DNA. RADICA’s versatility is validated against other targets such as Epstein-Barr virus (EBV) from human B cells and patients’ serum. RADICA can accurately detect and absolutely quantify EBV DNA with similar dynamic range of 0.5–2100 copies/μL (R2 value > 0.98) in 1 h without thermal cycling, providing a 4-fold faster alternative to digital PCR-based detection. RADICA therefore enables rapid and sensitive absolute quantification of nucleic acids which can be widely applied across clinical, research, and biomanufacturing areas.
Hydrogel-based colorectal cancer organoid co-culture models
Acta Biomaterialia, (2021), Available online 31 December 2020. doi: 10.1016/j.actbio.2020.12.037.
Xiaobei Luo, Eliza Li Shan Fong, Chaojun Zhua, Quy Xiao Xuan Lin, Man Xiong, Aimin Li, Tingting Li, Touati Benoukr, Hanry Yu, Side Liu
Abstract
The lack of cancer-associated fibroblasts (CAFs) in patient-derived organoid (PDO) models is a major limitation as CAFs contribute to tumor progression and drug resistance. In the present study, we addressed this problem by establishing in vitro conditions that enable the co-culture of colorectal cancer (CRC) PDO with patient-derived CAFs. Considering that the CRC extracellular matrix is high in hyaluronan and collagen I, we hypothesized that hyaluronan-gelatin hydrogels may serve as a suitable alternative 3D matrix to traditionally used basement membrane extracts to support the co-culture of CRC PDO and CAFs. We report the development of in vitro models consisting of CRC PDO encapsulated within a well-defined three-dimensional (3D) hyaluronan-gelatin hydrogel and co-cultured with patient-derived CAFs. Through RNA- and whole -exome sequencing, we first show that these hydrogels are capable of maintaining key molecular characteristics of the original patient tumors in CRC PDO but not support the culture of CAFs. Further, based on our findings that CRC PDO culture medium poorly supports CAF viability, we developed a co-culture strategy that maintains the viability of both CRC PDO and CAFs. We found that even in the absence of growth factors conventionally used to support CRC PDO culture, CAFs were able to maintain the proliferation of the cultured CRC PDO in the hydrogels and restore distinct biological pathways absent in the PDO culture alone but present in patient tissues. Lastly, we demonstrate that these CRC PDO-CAFs co-culture models are suitable for evaluating standard-of-care drugs, making them potentially very useful for realizing personalized cancer medicine.
Isolation of Primary Rat Hepatocytes with Multiparameter Perfusion Control
J Vis Exp. 2021 Apr 5;(170). doi: 10.3791/62289.
Inn Chuan Ng, Li Zhang, Narelle Nichola Yi Ying Shen, Yun Ting Soong, Chan Way Ng, Phoebe Kang Sheing Koh, Yan Zhou, Hanry Yu
Abstract
Primary hepatocytes are widely used in basic research on liver diseases and for toxicity testing in vitro. The two-step collagenase perfusion procedure for primary hepatocyte isolation is technically challenging, especially in portal vein cannulation. The procedure is also prone to occasional contamination and variations in perfusion conditions due to difficulties in the assembly, optimization, or maintenance of the perfusion setup. Here, a detailed protocol for an improved two-step collagenase perfusion procedure with multiparameter perfusion control is presented. Primary rat hepatocytes were successfully and reliably isolated by taking the necessary technical precautions at critical steps of the procedure, and by reducing the operational difficulty and mitigating the variability of perfusion parameters through the adoption of a special intravenous catheter, standardized sterile disposable tubing, temperature control, and real-time monitoring and alarm system. The isolated primary rat hepatocytes consistently exhibit high cell viability (85%-95%), yield (2-5 x 108 cells per 200-300 g rat) and functionality (albumin, urea and CYP activity). The procedure was complemented by an integrated perfusion system, which is compact enough to be set up in the laminar flow hood to ensure aseptic operation.
Three-Dimensional Macroporous Sponge for the Culture of Hepatocellular Carcinoma Patient-Derived Xenograft Organoids
SLAS Technology, (2021), First Published March 27, 2021. doi: 10.1177/24726303211000685.
Tan Boon Toh, Zheng Liu, Hanry Yu, Eliza Li Shan Fong
Abstract
This protocol focuses on the culture of cells harvested from hepatocellular carcinoma (HCC) patient-derived xenografts (PDXs) as organoids using a cellulosic macroporous sponge scaffold. Compared with many other epithelial cancer types, the viability of HCC cells directly derived from patients or PDX models is notoriously challenging to maintain in vitro. We previously developed a macroporous sponge scaffold uniquely designed to provide biochemical and mechanical cues that support the culture of normal hepatocytes as spheroids with maintained functionality. Leveraging our success using this sponge scaffold to maintain normal hepatocytes in vitro, we recently demonstrated that a similar sponge scaffold enables the maintenance of HCC PDX cells as organoids with preserved viability, molecular features, and heterogeneity.
ER-luminal [Ca 2+] regulation of InsP 3 receptor gating mediated by an ER-luminal peripheral Ca 2+-binding protein
Elife. 2020 May 18;9:e53531. doi: 10.7554/eLife.53531.
Horia Vais, Min Wang, Karthik Mallilankaraman, Riley Payne, Chris McKennan, Jeffrey T Lock, Lynn A Spruce, Carly Fiest, Matthew Yan-Lok Chan, Ian Parker, Steven H Seeholzer, J Kevin Foskett, Don-On Daniel Mak
Abstract
Modulating cytoplasmic Ca2+ concentration ([Ca2+]i) by endoplasmic reticulum (ER)-localized inositol 1,4,5-trisphosphate receptor (InsP3R) Ca2+-release channels is a universal signaling pathway that regulates numerous cell-physiological processes. Whereas much is known regarding regulation of InsP3R activity by cytoplasmic ligands and processes, its regulation by ER-luminal Ca2+ concentration ([Ca2+]ER) is poorly understood and controversial. We discovered that the InsP3R is regulated by a peripheral membrane-associated ER-luminal protein that strongly inhibits the channel in the presence of high, physiological [Ca2+]ER. The widely-expressed Ca2+-binding protein annexin A1 (ANXA1) is present in the nuclear envelope lumen and, through interaction with a luminal region of the channel, can modify high-[Ca2+]ER inhibition of InsP3R activity. Genetic knockdown of ANXA1 expression enhanced global and local elementary InsP3-mediated Ca2+ signaling events. Thus, [Ca2+]ER is a major regulator of InsP3R channel activity and InsP3R-mediated [Ca2+]i signaling in cells by controlling an interaction of the channel with a peripheral membrane-associated Ca2+-binding protein, likely ANXA1.
miR-142-3p Regulates BDNF Expression in Activated Rodent Microglia Through Its Target CAMK2A
Front Cell Neurosci. 2020 May 21;14:132. doi: 10.3389/fncel.2020.00132. eCollection 2020.
Neelima Gupta, Shweta Jadhav, Kai-Leng Tan, Genevieve Saw, Karthik Babu Mallilankaraman, S Thameem Dheen
Abstract
Microglia, the innate immune effector cells of the mammalian central nervous system (CNS), are involved in the development, homeostasis, and pathology of CNS. Microglia become activated in response to various insults and injuries and protect the CNS by phagocytosing the invading pathogens, dead neurons, and other cellular debris. Recent studies have demonstrated that the epigenetic mechanisms ensure the coordinated regulation of genes involved in microglial activation. In this study, we performed a microRNA (miRNA) microarray in activated primary microglia derived from rat pup’s brain and identified differentially expressed miRNAs targeting key genes involved in cell survival, apoptosis, and inflammatory responses. Interestingly, miR-142-3p, one of the highly up-regulated miRNAs in microglia upon lipopolysaccharide (LPS)-mediated activation, compared to untreated primary microglia cells was predicted to target Ca2+/calmodulin dependent kinase 2a (CAMK2A). Further, luciferase reporter assay confirmed that miR-142-3p targets the 3′UTR of Camk2a. CAMK2A has been implicated in regulating the expression of brain-derived neurotrophic factor (BDNF) and long-term potentiation (LTP), a cellular mechanism underlying memory and learning. Given this, this study further focused on understanding the miR-142-3p mediated regulation of the CAMK2A-BDNF pathway via Cyclic AMP-responsive element-binding protein (CREB) in activated microglia. The results revealed that CAMK2A was downregulated in activated microglia, suggesting an inverse relationship between miR-142-3p and Camk2a in activated microglia. Overexpression of miR-142-3p in microglia was found to decrease the expression of CAMK2A and subsequently BDNF through regulation of CREB phosphorylation. Functional analysis through shRNA-mediated stable knockdown of CAMK2A in microglia confirmed that the regulation of BDNF by miR-142-3p is via CAMK2A. Overall, this study provides a database of differentially expressed miRNAs in activated primary microglia and reveals that microglial miR-142-3p regulates the CAMK2A-CREB-BDNF pathway which is involved in synaptic plasticity.
Dynamic contrast-enhanced MRI of brown and beige adipose tissues
Magn Reson Med. 2020 Jul;84(1):384-395. doi: 10.1002/mrm.28118. Epub 2019 Dec 4.
Jadegoud Yaligar, Sanjay Kumar Verma, Venkatesh Gopalan, Rengaraj Anantharaj, Giang Thi Thu Le, Kavita Kaur, Karthik Mallilankaraman, Melvin Khee-Shing Leow, S Sendhil Velan
Abstract
Purpose
The vascular blood flow in brown adipose tissue (BAT) is important for handling triglyceride clearance, increased blood flow and oxygenation. We used dynamic contrast-enhanced (DCE)-MRI and fat fraction (FF) imaging for investigating vascular perfusion kinetics in brown and beige adipose tissues with cold exposure or treatment with β3-adrenergic agonist.
Methods
FF imaging and DCE-MRI using gadolinium-diethylenetriaminepentaacetic acid were performed in interscapular BAT (iBAT) and beige tissues using male Wister rats (n = 38). Imaging was performed at thermoneutral condition and with either cold exposure, treatment with pharmacological agent CL-316,243, or saline. DCE-MRI and FF data were co-registered to enhance the understanding of metabolic activity.
Results
Uptake of contrast agent in activated iBAT and beige tissues were significantly (P < .05) higher than nonactivated iBAT. The Ktrans and kep increased significantly in iBAT and beige tissues after treatment with either cold exposure or β3-adrenergic agonist. The FF decreased in activated iBAT and beige tissues. The Ktrans and FF from iBAT and beige tissues were inversely correlated (r = 0.97; r = 0.94). Significant increase in vascular endothelial growth factor expression and Ktrans in activated iBAT and beige tissues were in agreement with the increased vasculature and vascular perfusion kinetics. The iBAT and beige tissues were validated by measuring molecular markers.
Conclusion
Increased Ktrans and decreased FF in iBAT and beige tissues were in agreement with the vascular perfusion kinetics facilitating the clearance of free fatty acids. The methodology can be extended for the screening of browning agents.
Oxygen Glucose Deprivation Induced Prosurvival Autophagy Is Insufficient to Rescue Endothelial Function
Front Physiol. 2020 Sep 16;11:533683. doi: 10.3389/fphys.2020.533683. eCollection 2020.
Venkateswaran Natarajan, Tania Mah, Chen Peishi, Shu Yi Tan, Ritu Chawla, Thiruma Valavan Arumugam, Adaikalavan Ramasamy, Karthik Mallilankaraman
Abstract
Endothelial dysfunction, referring to a disturbance in the vascular homeostasis, has been implicated in many disease conditions including ischemic/reperfusion injury and atherosclerosis. Endothelial mitochondria have been increasingly recognized as a regulator of calcium homeostasis which has implications in the execution of diverse cellular events and energy production. The mitochondrial calcium uniporter complex through which calcium enters the mitochondria is composed of several proteins, including the pore-forming subunit MCU and its regulators MCUR1, MICU1, and MICU2. Mitochondrial calcium overload leads to opening of MPTP (mitochondrial permeability transition pore) and results in apoptotic cell death. Whereas, blockage of calcium entry into the mitochondria results in reduced ATP production thereby activates AMPK-mediated pro-survival autophagy. Here, we investigated the expression of mitochondrial calcium uniporter complex components (MCU, MCUR1, MICU1, and MICU2), induction of autophagy and apoptotic cell death in endothelial cells in response to oxygen-glucose deprivation. Human pulmonary microvascular endothelial cells (HPMVECs) were subjected to oxygen-glucose deprivation (OGD) at 3-h timepoints up to 12 h. Interestingly, except MCUR1 which was significantly downregulated, all other components of the uniporter (MCU, MICU1, and MICU2) remained unchanged. MCUR1 downregulation has been shown to activate AMPK mediated pro-survival autophagy. Similarly, MCUR1 downregulation in response to OGD resulted in AMPK phosphorylation and LC3 processing indicating the activation of pro-survival autophagy. Despite the activation of autophagy, OGD induced Caspase-mediated apoptotic cell death. Blockade of autophagy did not reduce OGD-induced apoptotic cell death whereas serum starvation conferred enough cellular and functional protection. In conclusion, the autophagic flux induced by MCUR1 downregulation in response to OGD is insufficient in protecting endothelial cells from undergoing apoptotic cell death and requires enhancement of autophagic flux by additional means such as serum starvation.
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)
Autophagy. 2021 Jan;17(1):1-382. doi: 10.1080/15548627.2020.1797280. Epub 2021 Feb 8.
Karthik Mallilankaraman et al
Abstract
Epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway involved in long-term potentiation and synaptic plasticity in rats
Glia. 2020 Mar;68(3):656-669. doi: 10.1002/glia.23748. Epub 2019 Nov 8.
Genevieve Saw, Kumar Krishna, Neelima Gupta, Tuck Wah Soong, Karthik Mallilankaraman, Sreedharan Sajikumar, S Thameem Dheen
Abstract
Microglia are the main form of immune defense in the central nervous system. Microglia express phosphatidylinositol 3-kinase (PI3K), which has been shown to play a significant role in synaptic plasticity in neurons and inflammation via microglia. This study shows that microglial PI3K is regulated epigenetically through histone modifications and posttranslationally through sumoylation and is involved in long-term potentiation (LTP) by modulating the expression of brain-derived neurotrophic factor (BDNF), which has been shown to be involved in neuronal synaptic plasticity. Sodium butyrate, a histone deacetylase inhibitor, upregulates PI3K expression, the phosphorylation of its downstream effectors, AKT and cAMP response element-binding protein (CREB), and the expression of BDNF in microglia, suggesting that BDNF secretion is regulated in microglia via epigenetic regulation of PI3K. Further, knockdown of SUMO1 in BV2 microglia results in a decrease in the expression of PI3K, the phosphorylation of AKT and CREB, as well as the expression of BDNF. These results suggest that microglial PI3K is epigenetically regulated by histone modifications and posttranslationally modified by sumoylation, leading to altered expression of BDNF. Whole-cell voltage-clamp showed the involvement of microglia in neuronal LTP, as selective ablation or disruption of microglia with clodronate in rat hippocampal slices abolished LTP. However, LTP was rescued when the same hippocampal slices were treated with active PI3K or BDNF, indicating that microglial PI3K/AKT signaling contributes to LTP and synaptic plasticity. Understanding the mechanisms by which microglial PI3K influences synapses provides insights into the ways it can modulate synaptic transmission and plasticity in learning and memory.
Mitochondrial Dysfunction in Age-Related Metabolic Disorders
Proteomics. 2020 Mar;20(5-6):e1800404. doi: 10.1002/pmic.201800404. Epub 2020 Mar 17.
Venkateswaran Natarajan Ritu Chawla, Tania Mah, Rajesh Vivekanandan, Shu Yi Tan, Priscila Y Sato, Karthik Mallilankaraman
Abstract
Aging is a natural biological process in living organisms characterized by receding bioenergetics. Mitochondria are crucial for cellular bioenergetics and thus an important contributor to age-related energetics deterioration. In addition, mitochondria play a major role in calcium signaling, redox homeostasis, and thermogenesis making this organelle a major cellular component that dictates the fate of a cell. To maintain its quantity and quality, mitochondria undergo multiple processes such as fission, fusion, and mitophagy to eliminate or replace damaged mitochondria. While this bioenergetics machinery is properly protected, the functional decline associated with age and age-related metabolic diseases is mostly a result of failure in such protective mechanisms. In addition, metabolic by-products like reactive oxygen species also aid in this destructive pathway. Mitochondrial dysfunction has always been thought to be associated with diseases. Moreover, studies in recent years have pointed out that aging contributes to the decay of mitochondrial health by promoting imbalances in key mitochondrial-regulated pathways. Hence, it is crucial to understand the nexus of mitochondrial dysfunction in age-related diseases. This review focuses on various aspects of basic mitochondrial biology and its status in aging and age-related metabolic diseases.
Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis
Cancers 2021, 13(8), 1882. doi: 10.3390/cancers13081882.
Arpita Datta, Shuo Deng, Vennila Gopal, Kenneth Chun-Hong Yap, Clarissa Esmeralda Halim, Mun Leng Lye, Mei Shan Ong, Tuan Zea Tan, Gautam Sethi, Shing Chuan Hooi, Alan Prem Kumar, and Celestial T. Yap
Abstract
In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells—highlight some future perspectives in cancer therapy by targeting cytoskeleton.
FEZ1 forms complexes with CRMP1 and DCC to regulate axon and dendrite development
eNeuro 26 March 2021, ENEURO.0193-20.2021; DOI: https://doi.org/10.1523/ENEURO.0193-20.2021
Jie Yin Chua, Shi Jun Ng, Oleksandr Yagensky, Erich E Wanker and John Jia En Chua
Abstract
Elaboration of neuronal processes is an early step in neuronal development. Guidance cues must work closely with intracellular trafficking pathways to direct expanding axons and dendrites to their target neurons during the formation of neuronal networks. However, how such coordination is achieved remains incompletely understood. Here, we characterize an interaction between FEZ1, an adapter involved in synaptic protein transport, and CRMP1, a protein that functions in growth cone guidance, at neuronal growth cones. We show that similar to CRMP1 loss-of-function mutants, FEZ1 deficiency in rat hippocampal neurons causes growth cone collapse and impairs axonal development. Strikingly, FEZ1-deficient neurons also exhibited a reduction in dendritic complexity stronger than that observed in CRMP1-deficient neurons, suggesting that the former could partake in additional developmental signaling pathways. Supporting this, FEZ1 colocalizes with VAMP2 in developing hippocampal neurons and forms a separate complex with Deleted in Colorectal Cancer and Syntaxin-1, components of the Netrin-1 signaling pathway that are also involved in regulating axon and dendrite development. Significantly, developing axons and dendrites of FEZ1-deficient neurons fail to respond to Netrin-1 or Netrin-1 and Sema3A treatment, respectively. Taken together, these findings highlight the importance of FEZ1 as a common effector to integrate guidance signaling pathways with intracellular trafficking to mediate axo-dendrite development during neuronal network formation.
Managing Heat Stress in the Workplace
Workplace Safety and Health Guidelines. doi: 10.13140/RG.2.2.22210.81604.
Jason Lee, Edward Lo Hong Yee, Alexander Gorny, Ng Yih Yng, Joshua Wong, Cheong Wee Kiong, Don Wilson Paua Boon Leng, Foo May Ling, Kenneth Choy, Lucy Leong,Edison J Loh
Abstract
Assessment of dehydration using body mass changes of elite marathoners in the tropics
Xiang Ren Tan, Ivan Cherh Chiet Low, Chris Byrne, Ru Wang, Jason Kai Wei Lee
Abstract
Objectives
The ACSM recommends drinking to avoid loss of body mass >2% during exercise to avert compromised performance. Our study aimed to assess the level of dehydration in elite runners following a city marathon in a tropical environment.
Design
Prospective cohort design.
Methods
Twelve elite runners (6 males, 6 females; age 24–41 y) had body mass measured to the nearest 0.01 kg in their race attire immediately before and after the 2017 Standard Chartered Singapore Marathon 2017. Body mass change was corrected for respiratory water loss, gas exchange, and sweat retained in clothing, and expressed as % of pre-race mass (i.e. % dehydration).
Results
Data are expressed as means ± SD (range). Dry bulb temperature and humidity were 27.9 ± 0.1 °C (27.4–28.3 °C) and 79 ± 2% (73–82%). Finish time was 155 ± 10 min (143−172 min). Male runners finishing positions ranged from 2–12 out of 7627 finishers, whilst female runners placed 1–8 out of 1754 finishers. Body mass change (loss) and % dehydration for all runners were 2.5 ± 0.5 kg (1.8–3.5 kg) and 4.6 ± 0.9% (3.6–6.8%). Male runners experienced body mass loss of 2.8 ± 0.5 kg and 4.9 ± 1.2% while females experienced body mass loss of 2.1 ± 0.2 kg and 4.3 ± 0.6%.
Conclusions
Despite experiencing dehydration (4.6% body mass loss) two-fold higher than current fluid replacement guidelines recommend (≤2%), elite male and female runners performed successfully and without medical complication in a hot weather marathon.
Dysfunction in nonsense-mediated decay, protein homeostasis, mitochondrial function, and brain connectivity in ALS-FUS mice with cognitive deficits
Acta Neuropathol Commun. 2021 Jan 6;9(1):9. doi: 10.1186/s40478-020-01111-4.
Wan Yun Ho, Ira Agrawal, Sheue-Houy Tyan, Emma Sanford, Wei-Tang Chang, Kenneth Lim, Jolynn Ong, Bernice Siu Yan Tan, Aung Aung Kywe Moe, Regina Yu, Peiyan Wong, Greg Tucker-Kellogg, Edward Koo, Kai-Hsiang Chuang, Shuo-Chien Ling
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of the same disease spectrum of adult-onset neurodegenerative diseases that affect the motor and cognitive functions, respectively. Multiple common genetic loci such as fused in sarcoma (FUS) have been identified to play a role in ALS and FTD etiology. Current studies indicate that FUS mutations incur gain-of-toxic functions to drive ALS pathogenesis. However, how the disease-linked mutations of FUS affect cognition remains elusive. Using a mouse model expressing an ALS-linked human FUS mutation (R514G-FUS) that mimics endogenous expression patterns, we found that FUS proteins showed an age-dependent accumulation of FUS proteins despite the downregulation of mouse FUS mRNA by the R514G-FUS protein during aging. Furthermore, these mice developed cognitive deficits accompanied by a reduction in spine density and long-term potentiation (LTP) within the hippocampus. At the physiological expression level, mutant FUS is distributed in the nucleus and cytosol without apparent FUS aggregates or nuclear envelope defects. Unbiased transcriptomic analysis revealed a deregulation of genes that cluster in pathways involved in nonsense-mediated decay, protein homeostasis, and mitochondrial functions. Furthermore, the use of in vivo functional imaging demonstrated widespread reduction in cortical volumes but enhanced functional connectivity between hippocampus, basal ganglia and neocortex in R514G-FUS mice. Hence, our findings suggest that disease-linked mutation in FUS may lead to changes in proteostasis and mitochondrial dysfunction that in turn affect brain structure and connectivity resulting in cognitive deficits.
TDP-43 maximizes nerve conduction velocity by repressing a cryptic exon for paranodal junction assembly in Schwann cells
Elife. 2021 Mar 10;10:e64456. doi: 10.7554/eLife.64456.
Kae-Jiun Chang, Ira Agrawal, Anna Vainshtein, Wan Yun Ho, Wendy Xin, Greg Tucker-Kellogg, Keiichiro Susuki, Elior Peles, Shuo-Chien Ling, Jonah R Chan
Abstract
TDP-43 is extensively studied in neurons in physiological and pathological contexts. However, emerging evidence indicates that glial cells are also reliant on TDP-43 function. We demonstrate that deletion of TDP-43 in Schwann cells results in a dramatic delay in peripheral nerve conduction causing significant motor deficits in mice, which is directly attributed to the absence of paranodal axoglial junctions. By contrast, paranodes in the central nervous system are unaltered in oligodendrocytes lacking TDP-43. Mechanistically, TDP-43 binds directly to Neurofascin mRNA, encoding the cell adhesion molecule essential for paranode assembly and maintenance. Loss of TDP-43 triggers the retention of a previously unidentified cryptic exon, which targets Neurofascin mRNA for nonsense-mediated decay. Thus, TDP-43 is required for neurofascin expression, proper assembly and maintenance of paranodes, and rapid saltatory conduction. Our findings provide a framework and mechanism for how Schwann cell-autonomous dysfunction in nerve conduction is directly caused by TDP-43 loss-of-function.
Regulatory T Cells Inhibit T Cell Activity by Downregulating CD137 Ligand via CD137 Trogocytosis
Cells. 2021 Feb 9;10(2):353. doi: 10.3390/cells10020353.
Khang Luu, Mugdha Vijay Patwardhan, Qun Zeng, Stina L Wickström, Andreas Lundqvist, Herbert Schwarz
Abstract
CD137 is a costimulatory molecule expressed on activated T cells. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC), which use the CD137-CD137L system to enhance immune responses. It was, therefore, surprising to discover CD137 expression on regulatory T cells (Treg). The function of CD137 in Treg are controversial. While some studies report that CD137 signalling converts Treg to effector T cells (Teff), other studies find that CD137-expressing Treg display a stronger inhibitory activity than CD137- Treg. Here, we describe that CD137 on Treg binds to CD137L on APC, upon which one of the two molecules is transferred via trogocytosis to the other cell, where CD137-CD137L forms a complex that is internalized and deprives APC of the immune-stimulatory CD137L. Truncated forms of CD137 that lack the cytoplasmic domain of CD137 are also able to downregulate CD137L, demonstrating that CD137 signalling is not required. Comparable data have been obtained with human and murine cells, indicating that this mechanism is evolutionarily conserved. These data describe trogocytosis of CD137 and CD137L as a new mechanism employed by Treg to control immune responses by downregulating the immunostimulatory CD137L on APC.
Ectopic CD137 expression by rhabdomyosarcoma provides selection advantages but allows immunotherapeutic targeting
Oncoimmunology. 2021 Feb 4;10(1):1877459. doi: 10.1080/2162402X.2021.1877459.
Kang Yi Lee, Hiu Yi Wong, Qun Zeng, Jia Le Lin, Man Si Cheng, Chik Hong Kuick, Kenneth Tou En Chang, Amos Hong Pheng Loh, Herbert Schwarz
Abstract
Rhabdomyosarcoma (RMS) is a heterogeneous soft tissue neoplasm most frequently found in children and adolescents. As the prognosis for recurrent and metastatic RMS remains poor, immunotherapies are hoped to improve quality of life and survival. CD137 is a member of tumor necrosis factor receptor family and a T cell costimulatory molecule which induces potent cellular immune responses that are able to eliminate malignant cells. Therefore, it was puzzling to find expression of CD137 on an RMS tissue microarray by multiplex staining. CD137 is not only expressed by infiltrating T cells but also by malignant RMS cells. Functional in vitro experiments demonstrate that CD137 on RMS cells is being transferred to adjacent antigen-presenting cells by trogocytosis, where it downregulates CD137 ligand, and thereby reduces T cell costimulation which results in reduced killing of RMS cells. The transfer of CD137 and the subsequent downregulation of CD137 ligand is a physiological negative feedback mechanism that is likely usurped by RMS, and may facilitate its escape from immune surveillance. In addition, CD137 signals into RMS cells and induces IL-6 and IL-8 secretion, which are linked to RMS metastasis and poor prognosis. However, the ectopic expression of CD137 on RMS cells is an Achilles’ heel that may be utilized for immunotherapy. Natural killer cells expressing an anti-CD137 chimeric antigen receptor specifically kill CD137-expressing RMS cells. Our study implicates ectopic CD137 expression as a pathogenesis mechanism in RMS, and it demonstrates that CD137 may be a novel target for immunotherapy of RMS.
Age-related changes in hippocampal-dependent synaptic plasticity and memory mediated by p75 neurotrophin receptor
Aging Cell. 2021 Feb;20(2):e13305. doi: 10.1111/acel.13305. Epub 2021 Jan 15.
Lik-Wei Wong, Yee Song Chong, Wei Lin, Lilian Kisiswa, Eunice Sim, Carlos F Ibáñez, Sreedharan Sajikumar
Abstract
The plasticity mechanisms in the nervous system that are important for learning and memory are greatly impacted during aging. Notably, hippocampal-dependent long-term plasticity and its associative plasticity, such as synaptic tagging and capture (STC), show considerable age-related decline. The p75 neurotrophin receptor (p75NTR ) is a negative regulator of structural and functional plasticity in the brain and thus represents a potential candidate to mediate age-related alterations. However, the mechanisms by which p75NTR affects synaptic plasticity of aged neuronal networks and ultimately contribute to deficits in cognitive function have not been well characterized. Here, we report that mutant mice lacking the p75NTR were resistant to age-associated changes in long-term plasticity, associative plasticity, and associative memory. Our study shows that p75NTR is responsible for age-dependent disruption of hippocampal homeostatic plasticity by modulating several signaling pathways, including BDNF, MAPK, Arc, and RhoA-ROCK2-LIMK1-cofilin. p75NTR may thus represent an important therapeutic target for limiting the age-related memory and cognitive function deficits.
Inactive variants of death receptor p75 NTR reduce Alzheimer’s neuropathology by interfering with APP internalization
EMBO J. 2021 Jan 15;40(2):e104450. doi: 10.15252/embj.2020104450.
Chenju Yi, Ket Yin Goh, Lik-Wei Wong, Ajeena Ramanujan, Kazuhiro Tanaka, Sreedharan Sajikumar, Carlos F Ibáñez
Abstract
A prevalent model of Alzheimer’s disease (AD) pathogenesis postulates the generation of neurotoxic fragments derived from the amyloid precursor protein (APP) after its internalization to endocytic compartments. The molecular pathways that regulate APP internalization and intracellular trafficking in neurons are incompletely understood. Here, we report that 5xFAD mice, an animal model of AD, expressing signaling-deficient variants of the p75 neurotrophin receptor (p75NTR ) show greater neuroprotection from AD neuropathology than animals lacking this receptor. p75NTR knock-in mice lacking the death domain or transmembrane Cys259 showed lower levels of Aβ species, amyloid plaque burden, gliosis, mitochondrial stress, and neurite dystrophy than global knock-outs. Strikingly, long-term synaptic plasticity and memory, which are completely disrupted in 5xFAD mice, were fully recovered in the knock-in mice. Mechanistically, we found that p75NTR interacts with APP at the plasma membrane and regulates its internalization and intracellular trafficking in hippocampal neurons. Inactive p75NTR variants internalized considerably slower than wild-type p75NTR and showed increased association with the recycling pathway, thereby reducing APP internalization and co-localization with BACE1, the critical protease for generation of neurotoxic APP fragments, favoring non-amyloidogenic APP cleavage. These results reveal a novel pathway that directly and specifically regulates APP internalization, amyloidogenic processing, and disease progression, and suggest that inhibitors targeting the p75NTR transmembrane domain may be an effective therapeutic strategy in AD.
Exercise rescues mitochondrial coupling in aged skeletal muscle: a comparison of different modalities in preventing sarcopenia
J Transl Med. 2021 Feb 16;19(1):71. doi: 10.1186/s12967-021-02737-1.
Colin Harper, Venkatesh Gopalan, Jorming Goh
Abstract
Skeletal muscle aging is associated with a decline in motor function and loss of muscle mass- a condition known as sarcopenia. The underlying mechanisms that drive this pathology are associated with a failure in energy generation in skeletal muscle, either from age-related decline in mitochondrial function, or from disuse. To an extent, lifelong exercise is efficacious in preserving the energetic properties of skeletal muscle and thus may delay the onset of sarcopenia. This review discusses the cellular and molecular changes in skeletal muscle mitochondria during the aging process and how different exercise modalities work to reverse these changes. A key factor that will be described is the efficiency of mitochondrial coupling-ATP production relative to O2 uptake in myocytes and how that efficiency is a main driver for age-associated decline in skeletal muscle function. With that, we postulate the most effective exercise modality and protocol for reversing the molecular hallmarks of skeletal muscle aging and staving off sarcopenia. Two other concepts pertinent to mitochondrial efficiency in exercise-trained skeletal muscle will be integrated in this review, including- mitophagy, the removal of dysfunctional mitochondrial via autophagy, as well as the implications of muscle fiber type changes with sarcopenia on mitochondrial function.
A 12-week aerobic exercise intervention results in improved metabolic function and lower adipose tissue and ectopic fat in high-fat diet fed rats
Biosci Rep. 2021 Jan 29;41(1):BSR20201707. doi: 10.1042/BSR20201707.
Venkatesh Gopalan, Jadegoud Yaligar, Navin Michael, Kavita Kaur, Rengaraj Anantharaj, Sanjay Kumar Verma, Suresh Anand Sadananthan, Giang Thi Thu Le, Jorming Goh, S Sendhil Velan
Abstract
Investigations of long-term exercise interventions in humans to reverse obesity is expensive and is hampered by poor compliance and confounders. In the present study, we investigated intrahepatic and muscle fat, visceral and subcutaneous fat pads, plasma metabolic profile and skeletal muscle inflammatory markers in response to 12-week aerobic exercise in an obese rodent model. Six-week-old male Wistar rats (n=20) were randomized to chow-fed control (Control, n=5), sedentary high-fat diet (HFD, n=5), chow-fed exercise (Exercise, n=5) and HFD-fed exercise (HFD+Exercise, n=5) groups. The exercise groups were subjected to 12 weeks of motorized treadmill running at a speed of 18 m/min for 30 min/day. Differences in post-intervention measures were assessed by analysis of covariance (ANCOVA), adjusted for baseline bodyweight and pre-intervention measures, where available. Post-hoc analyses were performed with Bonferroni correction. Plasma metabolic profile was worsened and fat pads, ectopic fat in muscle and liver and inflammatory markers in skeletal muscle were elevated in sedentary HFD-fed animals relative to chow-fed controls. HFD+Exercise animals had significantly lower leptin (P=0.0004), triglycerides (P=0.007), homeostatic model assessment of insulin resistance (HOMA-IR; P=0.065), intramyocellular lipids (IMCLs; P=0.003), intrahepatic lipids (IHLs; P<0.0001), body fat% (P=0.001), subcutaneous adipose tissue (SAT; P<0.0001), visceral adipose (P<0.0001) and total fat mass (P<0.0001), relative to sedentary HFD-fed animals, despite only modestly lower bodyweight. Messenger RNA (mRNA) expression of inflammatory markers Interleukin 6 (IL6) and Tumor necrosis factor α (TNFα) were also reduced with aerobic exercise in skeletal muscle. Our results suggest that 12 weeks of aerobic exercise training is effective in improving metabolic health, fat depots, ectopic fat and inflammation even against a high-fat dietary background.
Slow Gait, Subjective Cognitive Decline and Motoric Cognitive RISK Syndrome: Prevalence and Associated Factors in Community Dwelling Older Adults
J Nutr Health Aging. 2021;25(1):48-56. doi: 10.1007/s12603-020-1525-y.
Reshma A Merchant, J Goh, Y H Chan, J Y Lim, B Vellas
Abstract
Background: Motoric Cognitive Risk Syndrome (MCR), slow gait speed (SG) and subjective cognitive decline (SCD) are known to be harbingers of dementia. MCR is known to be associated with a 3-fold increased risk of future dementia, while SG can precede cognitive impairment.
Objective: We aim to determine the prevalence and demographics of MCR, slow gait alone (SG-A) and subjective cognitive decline alone (SCD-A) in community-dwelling older adults and association with physical, functional, cognition and psychosocial factors.
Methods: A total of 509 participants were classified into four groups according to presence of SG and/or SCD. Multinomial logistic regression was used to identify the factors associated with SG-A, SCD-A and MCR.
Results: The prevalence of MCR was 13.6%, SG-A 13.0% and SCD-A 35.0%. Prevalence of MCR doubled every decade in females with 27.7% of female ≥ 80 years old had MCR. Almost 4 in 10 had no SG or SCD (SG+SCD negative). MCR and SG-A groups were significantly older, had higher body mass index (BMI), lower education, lower global cognition scores especially in non-memory domains, higher prevalence of low grip strength and lower short physical performance battery scores than those with SCD-A and SG+SCD negative. In addition, the SG-A group had significantly higher prevalence of multi-morbidity and diabetes. The prevalence of pain, depression, frailty, social isolation and activity of daily living impairment were significantly higher in MCR. The global cognitive and functional scores for those with SCD-A were comparable to the SG+SCD negative group. The Malay ethnic group had the lowest prevalence of SCD but highest prevalence of SG. After adjusting for confounding factors, age, BMI, frailty status, instrumental activity of daily living, depression and pain remained significantly associated with MCR. For SG-A, age, BMI, education and number of chronic diseases remained significant.
Conclusion: Both MCR and SG-A are associated with global cognitive decline especially in the non-memory domains and lower functional scores. Gait speed is a good predictor of negative outcomes and should be considered as the ‘sixth’ vital sign. Long term prospective studies are needed to evaluate: i) the conversion to dementia in different ethnic groups and ii) effect of targeted physical and / or dual task exercise on delaying the conversion to dementia and / or improvement in physical measures and reduction of disability.
Loss of FEZ1, a gene deleted in Jacobsen syndrome, causes locomotion defects and early mortality by impairing motor neuron development
Hum Mol Genet. 2021 Jan 4;ddaa281. doi: 10.1093/hmg/ddaa281.
Saravanan Gunaseelan, Ziyin Wang, Venetia Kok Jing Tong, Sylvester Wong Shu Ming, Rafhanah Banu Bte Abdul Razar, Sumitra Srimasorn, Wei-Yi Ong, Kah-Leong Lim, John Jia En Chua
Abstract
FEZ1-mediated axonal transport plays important roles in central nervous system development but its involvement in the peripheral nervous system is not well-characterised. FEZ1 is deleted in Jacobsen syndrome (JS), an 11q terminal deletion developmental disorder. JS patients display impaired psychomotor skills, including gross and fine motor delay, suggesting that FEZ1 deletion may be responsible for these phenotypes, given its association with the development of motor-related circuits. Supporting this hypothesis, our data shows that FEZ1 is selectively expressed in the rat brain and spinal cord. Its levels progressively increase over the developmental course of human motor neurons derived from embryonic stem cells. Deletion of FEZ1 strongly impaired axon and dendrite development, and significantly delayed the transport of synaptic proteins into developing neurites. Concurring with these observations, Drosophila unc-76 mutants showed severe locomotion impairments, accompanied by a strong reduction of synaptic boutons at neuromuscular junctions. These abnormalities were ameliorated by pharmacological activation of UNC-51/ATG1, a FEZ1-activating kinase, with rapamycin and metformin. Collectively, the results highlight a role for FEZ1 in motor neuron development and implicate its deletion as an underlying cause of motor impairments in JS patients.
Identification of CD137-Expressing B Cells in Multiple Sclerosis Which Secrete IL-6 Upon Engagement by CD137 Ligand
Front Immunol. 2020 Nov 6;11:571964. doi: 10.3389/fimmu.2020.571964. eCollection 2020.
Hiu Yi Wong, Ankshita Prasad, Shu Uin Gan, John Jia En Chua, Herbert Schwarz
Abstract
The potent costimulatory effect of CD137 has been implicated in several murine autoimmune disease models. CD137 costimulates and polarizes antigen-specific T cells toward a potent Th1/Tc1 response, and is essential for the development of experimental autoimmune encephalomyelitis (EAE), a murine model of Multiple Sclerosis (MS). This study aimed to investigate a role of CD137 in MS. Immunohistochemical and immunofluorescence staining of MS brain tissues was used to identify expression of CD137. CD137+ cells were identified in MS brain samples, with active lesions having the highest frequency of CD137+ cells. CD137 expression was found on several leukocyte subsets, including T cells, B cells and endothelial cells. In particular, CD137+ B cells were found in meningeal infiltrates. In vitro experiments showed that CD137 engagement on activated B cells increased early TNF and persistent IL-6 secretion with increased cell proliferation. These CD137+ B cells could interact with CD137L-expressing cells, secrete pro-inflammatory cytokines and accumulate in the meningeal infiltrate. This study demonstrates CD137 expression by activated B cells, enhancement of the inflammatory activity of B cells upon CD137 engagement, and provides evidence for a pathogenic role of CD137+ B cells in MS.
Resveratrol attenuates TLR-4 mediated inflammation and elicits therapeutic potential in models of sepsis
Sci Rep. 2020 Nov 2;10(1):18837. doi: 10.1038/s41598-020-74578-9.
Binbin Wang, Gregory Lucien Bellot, Kartini Iskandar, Tsung Wen Chong, Fera Yiqian Goh, June Jingyi Tai, Herbert Schwarz, Siew Cheng Wong, Shazib Pervaiz
Abstract
Sepsis is a potentially fatal condition triggered by systemic inflammatory response to infection. Due to the heightened immune reactivity and multi-organ pathology, treatment options are limited and several clinical trials have not produced the desired outcome, hence the interest in the discovery of novel therapeutic strategies. The polyphenol resveratrol (RSV) has shown promise against several pathological states, including acute and chronic inflammation. In this study, we evaluated its therapeutic potential in a murine model of sepsis and in patients undergoing transrectal ultrasound biopsy. RSV was able to inhibit lipopolysaccharide (LPS) stimulated inflammatory responses through blocking Phospholipase D (PLD) and its downstream signaling molecules SphK1, ERK1/2 and NF-κB. In addition, RSV treatment resulted in the downregulation of MyD88, an adaptor molecule in the TLR4 signaling pathway, and this effect at least in part, involved RSV-induced autophagy. Notably, RSV protected mice against polymicrobial septic shock induced upon cecal ligation and puncture, and inhibited pro-inflammatory cytokine production by human monocytes from transrectal ultrasound (TRUS) biopsy patients. Together, these findings demonstrate the immune regulatory activity of RSV and highlight its therapeutic potential in the management of sepsis.
CD137 Ligand-CD137 Interaction is Required For Inflammasome-Associated Brain Injury Following Ischemic Stroke
Neuromolecular Med. 2020 Dec;22(4):474-483. doi: 10.1007/s12017-020-08623-1.
David Y Fann, Emily Pauline Nickles, Luting Poh, Vismitha Rajeev, Sharmelee Selvaraji, Herbert Schwarz, Thiruma V Arumugam
Abstract
The CD137L-CD137 axis is a potent co-stimulatory immune checkpoint regulator that forms a bidirectional signaling pathway between the CD137 ligand (CD137L) and CD137 receptor to regulate immunological activities. This study investigated the potential involvement of the CD137L-CD137 axis on inflammasome-associated brain injury and neurological deficits in a mouse model of focal ischemic stroke. Cerebral ischemia was induced in male C57BL/6J wild-type (WT), CD137L-deficient (CD137L KO) and CD137-deficient (CD137 KO) mice by middle cerebral artery occlusion (MCAO; 60 min), followed by reperfusion (6 h and 24 h). Brain infarct volume and neurological deficit scores were significantly lower in both CD137L KO and CD137 KO mice compared to WT controls. Moreover, CD137L-deficient brains had significantly lower levels of the pyroptotic protein, NT-Gasdermin D, while CD137-deficient brains had significantly lower levels of the pro-apoptotic proteins, cleaved caspase-3, pyroptotic protein, NT-Gasdermin D, and of the secondary pyroptotic protein NT-Gasdermin E, following ischemic stroke. This protection by CD137L and CD137 deletion was associated with a significant decrease in inflammasome signaling. In conclusion, our data provide evidence for the first time that the CD137L-CD137 axis contributes to brain injury and neurological deficits by activating the inflammasome signaling pathway following ischemic stroke.
The role of trogocytosis in immune surveillance of Hodgkin lymphoma
Oncoimmunology. 2020 Jun 17;9(1):1781334. doi: 10.1080/2162402X.2020.1781334.
Qun Zeng, Herbert Schwarz
Abstract
Hodgkin lymphoma (HL) is a unique type of hematopoietic cancer that has few tumor cells but a massive infiltration of immune cells. Findings on how the cancerous Hodgkin and Reed-Sternberg (HRS) cells survive and evade immune surveillance have facilitated the development of novel immunotherapies for HL. Trogocytosis is a fast process of intercellular transfer of membrane patches, which can significantly affect immune responses. In this review, we summarize the current knowledge of how trogocytosis contributes to the suppression of immune responses in HL. We focus on the ectopic expression of CD137 on HRS cells, the cause of its expression, and its implication on developing novel therapies for HL. Further, we review data demonstrating that similar mechanisms apply to CD30, PD-L1 and CTLA-4.
CD137 / CD137 ligand signalling regulates the immune balance: A potential target for novel immunotherapy of autoimmune diseases
J Autoimmun. 2020 Aug;112:102499. doi: 10.1016/j.jaut.2020.102499.
Hiu Yi Wong, Herbert Schwarz
Abstract
CD137 (TNFRSF9, 4-1BB) is a potent co-stimulatory molecule of the tumour necrosis factor receptor superfamily (TNFRSF) that is expressed by activated T cells. CD137/CD137 ligand (CD137L) signalling primarily induces a potent cell-mediated immune response, while signalling of cell surface-expressed CD137L into antigen presenting cells enhances their activation, differentiation and migratory capacity. Studies have shown that bidirectional CD137/CD137L signalling plays an important role in the pathogenesis of autoimmune diseases. This review discusses the mechanisms how CD137/CD137L signalling contributes to immune deviation of helper T cell pathways in various murine models, and the potential of developing immunotherapies targeting CD137/CD137L signalling for the treatment of autoimmune diseases.
ALS motor neurons exhibit hallmark metabolic defects that are rescued by SIRT3 activation
Cell Death Differ. 2020 Nov 12. doi: 10.1038/s41418-020-00664-0.
Jin-Hui Hor, Munirah Mohamad Santosa, Valerie Jing Wen Lim, Beatrice Xuan Ho, Amy Taylor, Zi Jian Khong, John Ravits, Yong Fan, Yih-Cherng Liou, Boon-Seng Soh, Shi-Yan Ng
Abstract
Motor neurons (MNs) are highly energetic cells and recent studies suggest that altered energy metabolism precede MN loss in amyotrophic lateral sclerosis (ALS), an age-onset neurodegenerative disease. However, clear mechanistic insights linking altered metabolism and MN death are still missing. In this study, induced pluripotent stem cells from healthy controls, familial ALS, and sporadic ALS patients were differentiated toward spinal MNs, cortical neurons, and cardiomyocytes. Metabolic flux analyses reveal an MN-specific deficiency in mitochondrial respiration in ALS. Intriguingly, all forms of familial and sporadic ALS MNs tested in our study exhibited similar defective metabolic profiles, which were attributed to hyper-acetylation of mitochondrial proteins. In the mitochondria, Sirtuin-3 (SIRT3) functions as a mitochondrial deacetylase to maintain mitochondrial function and integrity. We found that activating SIRT3 using nicotinamide or a small molecule activator reversed the defective metabolic profiles in all our ALS MNs, as well as correct a constellation of ALS-associated phenotypes.
Targeting novel human transient receptor potential ankyrin 1 splice variation with splice-switching antisense oligonucleotides
PAIN, in Press. doi: 10.1097/j.pain.0000000000002216
Huang, Hua; Tay, Shermaine Huiping; Ng, Winanto; Ng, Shi Yan; Soong, Tuck Wah
Abstract
Activation of transient receptor potential ankyrin 1 (TRPA1) channels by both environmental irritants and endogenous inflammatory mediators leads to excitation of the nerve endings, resulting in acute sensation of pain, itch, or chronic neurogenic inflammation. As such, TRPA1 channels are actively pursued as therapeutic targets for various pathological nociception and pain disorders. We uncovered that exon 27 of human TRPA1 (hTRPA1) could be alternatively spliced into hTRPA1_27A and hTRPA1_27B splice variants. The resulting channel variants displayed reduced expression, weakened affinity to interact with WT, and suffered from complete loss of function because of disruption of the C-terminal coiled-coil domain. Using a human minigene construct, we revealed that binding of splicing factor serine/arginine-rich splicing factor 1 (SRSF1) to the exonic splicing enhancer was critical for the inclusion of intact exon 27. Knockdown of SRSF1, mutation within exonic splicing enhancer, or masking SRSF1 binding with antisense oligonucleotides promoted alternative splicing within exon 27. Finally, antisense oligonucleotides-induced alternative splicing produced transcript and protein variants that could be functionally determined as diminished endogenous TRPA1 activity in human Schwann cell-line SNF96.2 and hiPSCs-derived sensory neurons. The outcome of the work could potentially offer a novel therapeutic strategy for treating pain by targeting alternative splicing of hTRPA1.
Pulsed electromagnetic fields synergize with graphene to enhance dental pulp stem cell-derived neurogenesis by selectively targeting TRPC1 channels
Eur Cell Mater. 2021 Mar 1;41:216-232. doi: 10.22203/eCM.v041a16
T T Madanagopal, Y K Tai, S H Lim, C Hh Fong, T Cao, V Rosa, A Franco-Obregón
Abstract
Conventional root canal treatment replaces the infected pulp with defined materials. Alternative cell-based tissue engineering strategies aim to regenerate a fully functional pulp within the root canal. Despite recent advances in this area, however, the regeneration of an innervated pulp remains a major challenge in the field. Both graphene (2DG) and pulsed electromagnetic fields (PEMFs) independently have been shown to promote diverse cellular developmental programs. The present study showed that 2DG promoted the neurogenic induction of human dental pulp stem cells (hDPSCs) by upregulating and accelerating the expression of mature neuronal markers. Notably, 2DG induced the highest expression of transient receptor potential canonical cation channel type 1 (TRPC1) during early neurogenesis. As brief PEMF exposure promotes in vitro differentiation by activating a TRPC1-mitochondrial axis, an opportunity to combine 2DG with developmentally targeted PEMF exposure for synergistic effects was realizable. Neurogenic gene expression, neurotransmitter release, and reactive oxygen species (ROS) production were greatly enhanced by a brief (10 min) and low amplitude (2 mT) PEMF exposure timed to coincide with the highest TRPC1 expression from hDPSCs on 2DG. In contrast, hDPSCs on glass were less responsive to PEMF exposure. The capacity of PEMFs to promote neurogenesis was precluded by the administration of penicillin/streptomycin, mirroring previous studies demonstrating that aminoglycoside antibiotics block TRPC1-mediated calcium entry and verifying the contribution of TRPC1 in this form of magnetoreception. Hence, graphene created a more conducive environment for subsequent PEMF-stimulated neurogenic induction of hDPSCs through their mutual capacity to activate TRPC1with subsequent ROS production.
Manipulating energy migration within single lanthanide activator forSwitchable upconversionemissions towards bidirectional photoactivation
Nat Commun 10, 4416 (2019). https://doi.org/10.1038/s41467-019-12374-4
Qingsong Mei, Akshaya Bansal, Muthu Kumara Gnanasammandhan Jayakumar, Zhiming Zhang, Jing Zhang, Hua Huang, Dejie Yu, Chrishan J. A. Ramachandra, Derek J. Hausenloy, Tuck Wah Soong & Yong Zhang
Abstract
Reliance on low tissue penetrating UV or visible light limits clinical applicability of phototherapy, necessitating use of deep tissue penetrating near-infrared (NIR) to visible light transducers like upconversion nanoparticles (UCNPs). While typical UCNPs produce multiple simultaneous emissions for unidirectional control of biological processes, programmable control requires orthogonal non-overlapping light emissions. These can be obtained through doping nanocrystals with multiple activator ions. However, this requires tedious synthesis and produces complicated multi-shell nanoparticles with a lack of control over emission profiles due to activator crosstalk. Herein, we explore cross-relaxation (CR), a non-radiative recombination pathway typically perceived as deleterious, to manipulate energy migration within the same lanthanide activator ion (Er3+) towards orthogonal red and green emissions, simply by adjusting excitation wavelength from 980 to 808 nm. These UCNPs allow programmable activation of two synergistic light-gated ion channels VChR1 and Jaws in the same cell to manipulate membrane polarization, demonstrated here for cardiac pacing.
Loss of TDP-43 in astrocytes leads to motor deficits by triggering A1-like reactive phenotype and triglial dysfunction
Audrey Yi Tyan Peng, Ira Agrawal, Wan Yun Ho, Yi-Chun Yen, Ashley J Pinter, Jerry Liu, Qi Xuan Cheryl Phua, Katrianne Bethia Koh, Jer-Cherng Chang, Emma Sanford, Jodie Hon Kiu Man, Peiyan Wong, David H Gutmann, Greg Tucker-Kellogg, Shuo-Chien Ling
Abstract
Patients with amyotrophic lateral sclerosis (ALS) can have abnormal TDP-43 aggregates in the nucleus and cytosol of their surviving neurons and glia. Although accumulating evidence indicates that astroglial dysfunction contributes to motor neuron degeneration in ALS, the normal function of TDP-43 in astrocytes are largely unknown, and the role of astroglial TDP-43 loss to ALS pathobiology remains to be clarified. Herein, we show that TDP-43-deleted astrocytes exhibit a cell-autonomous increase in GFAP immunoreactivity without affecting astrocyte or microglia proliferation. At the transcriptomic level, TDP-43-deleted astrocytes resemble A1-reactive astrocytes and induce microglia to increase C1q expression. These astrocytic changes do not cause loss of motor neurons in the spinal cord or denervation at the neuromuscular junction. In contrast, there is a selective reduction of mature oligodendrocytes, but not oligodendrocyte precursor cells, suggesting triglial dysfunction mediated by TDP-43 loss in astrocytes. Moreover, mice with astroglial TDP-43 deletion develop motor, but not sensory, deficits. Taken together, our results demonstrate that TDP-43 is required to maintain the protective functions of astrocytes relevant to the development of motor deficits in mice.
Deregulated expression of a longevity gene, Klotho, in the C9orf72 deletion mice with impaired synaptic plasticity and adult hippocampal neurogenesis
Wan Yun Ho, Sheeja Navakkode, Fujia Liu, Tuck Wah Soong & Shuo-Chien Ling
Abstract
Hexanucleotide repeat expansion of C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Synergies between loss of C9ORF72 functions and gain of toxicities from the repeat expansions contribute to C9ORF72-mediated pathogenesis. However, how loss of C9orf72 impacts neuronal and synaptic functions remains undetermined. Here, we showed that long-term potentiation at the dentate granule cells and long-term depression at the Schaffer collateral/commissural synapses at the area CA1 were reduced in the hippocampus of C9orf72 knockout mice. Using unbiased transcriptomic analysis, we identified that Klotho, a longevity gene, was selectively dysregulated in an age-dependent manner. Specifically, Klotho protein expression in the hippocampus of C9orf72 knockout mice was incorrectly enriched in the dendritic regions of CA1 with concomitant reduction in granule cell layer of dentate gyrus at 3-month of age followed by an accelerating decline during aging. Furthermore, adult hippocampal neurogenesis was reduced in C9orf72 knockout mice. Taken together, our data suggest that C9ORF72 is required for synaptic plasticity and adult neurogenesis in the hippocampus and Klotho deregulations may be part of C9ORF72-mediated toxicity.
Characteristics of Physical Fitness and Cardiometabolic Risk in Chinese University Students with Normal-Weight Obesity: A Cross-Sectional Study
Diabetes Metab Syndr Obes. 2020 Nov 4;13:4157-4167. doi: 10.2147/DMSO.S280350. eCollection 2020.
Qianqian Tian, Hui Wang, Keneilwe Kenny Kaudimba, Shanshan Guo, Haixin Zhang, Song Gao, Ruwen Wang, Xin Luan, Jason Kai Wei Lee, Peijie Chen, Tiemin Liu, Ru Wang
Abstract
Purpose: To (i) describe the characteristics of physical fitness and cardiometabolic risk in Chinese university students with normal-weight obesity (NWO); (ii) assess the association between NWO with physical fitness and cardiometabolic risk.
Methods: A total of 249 participants from the 2018 Shanghai University of Sport Alumni Health Cohort Study in China formed the study cohort. NWO was defined as normal body mass index (17.9-23.9 kg/m2 for males; 17.2-23.9 kg/m2 for females) but with excess body-fat percentage (≥20% for males; ≥30% for females). Body composition was assessed by dual-energy X-ray absorptiometry. Physical-fitness scores were calculated from a battery of sex-specific tests. Cardiometabolic risk was calculated using a continuous clustered risk (MetS) score.
Results: We found that 16.7% of male and 45.3% of female university students were classified as having NWO. Participants with NWO showed worse cardiorespiratory fitness than those with normal weight (NW) (male NWO (37±8) vs male NW (41±6) mL/kg/min, p<0.01; female NWO (31±4) vs female NW (33±6) mL/kg/min, p<0.01). NWO was associated negatively with the fitness score (OR = 0.853; 95% CI = 0.793-0.917) and was associated positively with the MetS score (1.280; 1.162-1.410).
Conclusion: University students with NWO were characterized by higher cardiometabolic risk and lower levels of physical fitness. Our findings implied that university students with NWO should be mindful of the potential hidden health risks of excess body fat and participate in exercise to enhance physical fitness.
Heat Stress and Thermal Perception amongst Healthcare Workers during the COVID-19 Pandemic in India and Singapore.
Int J Environ Res Public Health. 2020 Nov 3;17(21):8100. doi: 10.3390/ijerph17218100.
Jimmy Lee, Vidhya Venugopa, P K Latha, Sharifah Badriyah Alhadad, Clarence Hong Wei Leow, Nicholas Yong De Goh, Esther Tan, Tord Kjellstrom, Marco Morabito, Jason Kai Wei Lee
Abstract
<pThe need for healthcare workers (HCWs) to wear personal protective equipment (PPE) during the coronavirus disease 2019 (COVID-19) pandemic heightens their risk of thermal stress. We assessed the knowledge, attitudes, and practices of HCWs from India and Singapore regarding PPE usage and heat stress when performing treatment and care activities. One hundred sixty-five HCWs from India (n = 110) and Singapore (n = 55) participated in a survey. Thirty-seven HCWs from Singapore provided thermal comfort ratings before and after ice slurry ingestion. Differences in responses between India and Singapore HCWs were compared. A p-value cut-off of 0.05 depicted statistical significance. Median wet-bulb globe temperature was higher in India (30.2 °C (interquartile range [IQR] 29.1-31.8 °C)) than in Singapore (22.0 °C (IQR 18.8-24.8 °C)) (p < 0.001). Respondents from both countries reported thirst (n = 144, 87%), excessive sweating (n = 145, 88%), exhaustion (n = 128, 78%), and desire to go to comfort zones (n = 136, 84%). In Singapore, reports of air-conditioning at worksites (n = 34, 62%), dedicated rest area availability (n = 55, 100%), and PPE removal during breaks (n = 54, 98.2%) were higher than in India (n = 27, 25%; n = 46, 42%; and n = 66, 60%, respectively) (p < 0.001). Median thermal comfort rating improved from 2 (IQR 1-2) to 0 (IQR 0-1) after ice slurry ingestion in Singapore (p < 0.001). HCWs are cognizant of the effects of heat stress but might not adopt best practices due to various constraints. Thermal stress management is better in Singapore than in India. Ice slurry ingestion is shown to be practical and effective in promoting thermal comfort. Adverse effects of heat stress on productivity and judgment of HCWs warrant further investigation.
Efficacy of Ingesting an Oral Rehydration Solution after Exercise on Fluid Balance and Endurance Performance
Nutrients. 2020 Dec 15;12(12):3826. doi: 10.3390/nu12123826.
Priscilla Weiping Fan, Stephen F Burns, Jason Kai Wei Lee
Abstract
This study investigated the efficacy of ingesting an oral rehydration solution (DD) that has a high electrolyte concentration after exercise on fluid balance and cycling performance in comparison with a sports drink (SD) and water (WA). Nine healthy males aged 24 ± 2 years (mean ± SD), with peak oxygen uptake (VO2 peak) 55 ± 6 mL·kg-1·min-1 completed three experimental trials in a randomised manner ingesting WA, SD (carbohydrates: 62 g·L-1, sodium: 31 ± 3 mmol·L-1) or DD (carbohydrates: 33 g·L-1, sodium: 60 ± 3 mmol·L-1). On all trials, fluid was ingested during 75 min cycling at 65% VO2 peak (temperature: 30.4 ± 0.3 °C, relative humidity: 76 ± 1%, simulated wind speed: 8.0 ± 0.6 m·s-1) and during 2 h of recovery (temperature: 23.0 ± 1.0 °C, relative humidity: 67 ± 2%), with the total volume equivalent to 150% of sweat loss during the ride. A 45 min pre-load cycling time trial at a 65% VO2 peak followed by a 20 km time trial was conducted after a further 3 h of recovery. Fluid retention was higher with DD (30 ± 15%) than WA (-4 ± 19%; p < 0.001) and SD (10 ± 15%; p = 0.002). Mean ratings of palatability were similar among drinks (WA: 4.25 ± 2.60; SD: 5.61 ± 1.79; DD: 5.40 ± 1.58; p = 0.33). Although time trial performance was similar across all three trials (WA: 2365 ± 321 s; SD: 2252 ± 174 s; DD: 2268 ± 184 s; p = 0.65), the completion time was faster in eight participants with SD and seven participants with DD than with WA. Comparing SD with DD, completion time was reduced in five participants and increased in four participants. DD was more effective at restoring the fluid deficit during recovery from exercise than SD and WA without compromising the drink’s palatability with increased sodium concentration. Most individuals demonstrated better endurance exercise time trial performance with DD and SD than with WA.
Serine-70 phosphorylated Bcl-2 prevents oxidative stress-induced DNA damage by modulating the mitochondrial redox metabolism
Nucleic Acids Research, 48(22): 12727–12745. doi:10.1093/nar/gkaa1110.
Stephen Jun Fei Chong, Kartini Iskandar, Jolin Xiao Hui Lai, Jianhua Qu, Deepika Raman, Rebecca Valentin, Charles Herbaux, Mary Collins, Ivan Cherh Chiet Low, Thomas Loh, Matthew Davids, Shazib Pervaiz
Abstract
Bcl-2 phosphorylation at serine-70 (S70pBcl2) confers resistance against drug-induced apoptosis. Nevertheless, its specific mechanism in driving drug-resistance remains unclear. We present evidence that S70pBcl2 promotes cancer cell survival by acting as a redox sensor and modulator to prevent oxidative stress-induced DNA damage and execution. Increased S70pBcl2 levels are inversely correlated with DNA damage in chronic lymphocytic leukemia (CLL) and lymphoma patient-derived primary cells as well as in reactive oxygen species (ROS)- or chemotherapeutic drug-treated cell lines. Bioinformatic analyses suggest that S70pBcl2 is associated with lower median overall survival in lymphoma patients. Empirically, sustained expression of the redox-sensitive S70pBcl2 prevents oxidative stress-induced DNA damage and cell death by suppressing mitochondrial ROS production. Using cell lines and lymphoma primary cells, we further demonstrate that S70pBcl2 reduces the interaction of Bcl-2 with the mitochondrial complex-IV subunit-5A, thereby reducing mitochondrial complex-IV activity, respiration and ROS production. Notably, targeting S70pBcl2 with the phosphatase activator, FTY720, is accompanied by an enhanced drug-induced DNA damage and cell death in CLL primary cells. Collectively, we provide a novel facet of the anti-apoptotic Bcl-2 by demonstrating that its phosphorylation at serine-70 functions as a redox sensor to prevent drug-induced oxidative stress-mediated DNA damage and execution with potential therapeutic implications.
Resveratrol attenuates TLR-4 mediated inflammation and elicits therapeutic potential in models of sepsis
Scientific Reports. 2020 Nov 2;10(1):18837. doi: 10.1038/s41598-020-74578-9.
Binbin Wang, Gregory Lucien Bellot, Kartini Iskandar, Tsung Wen Chong, Fera Yiqian Goh, June Jingyi Tai, Herbert Schwarz, Siew Cheng Wong, Shazib Pervaiz
Abstract
Sepsis is a potentially fatal condition triggered by systemic inflammatory response to infection. Due to the heightened immune reactivity and multi-organ pathology, treatment options are limited and several clinical trials have not produced the desired outcome, hence the interest in the discovery of novel therapeutic strategies. The polyphenol resveratrol (RSV) has shown promise against several pathological states, including acute and chronic inflammation. In this study, we evaluated its therapeutic potential in a murine model of sepsis and in patients undergoing transrectal ultrasound biopsy. RSV was able to inhibit lipopolysaccharide (LPS) stimulated inflammatory responses through blocking Phospholipase D (PLD) and its downstream signaling molecules SphK1, ERK1/2 and NF-κB. In addition, RSV treatment resulted in the downregulation of MyD88, an adaptor molecule in the TLR4 signaling pathway, and this effect at least in part, involved RSV-induced autophagy. Notably, RSV protected mice against polymicrobial septic shock induced upon cecal ligation and puncture, and inhibited pro-inflammatory cytokine production by human monocytes from transrectal ultrasound (TRUS) biopsy patients. Together, these findings demonstrate the immune regulatory activity of RSV and highlight its therapeutic potential in the management of sepsis.
LAMA4 upregulation is associated with high liver metastasis potential and poor survival outcome of Pancreatic Cancer
Theranostics. 2020 Aug 13;10(22):10274-10289. doi: 10.7150/thno.47001. eCollection 2020.
Biao Zheng, Jianhua Qu, Kenoki Ohuchida, Haimin Feng, Stephen Jun Fei Chong, Zilong Yan, Yicui Piao, Peng Liu, Nan Sheng, Daiki Eguchi, Takao Ohtsuka, Kazuhiro Mizumoto, Zhong Liu, Shazib Pervaiz, Peng Gong, Masafumi Nakamura
Abstract
Rationale: Pancreatic cancer is one of the most difficult cancers to manage and its poor prognosis stems from the lack of a reliable early disease biomarker coupled with its highly metastatic potential. Liver metastasis accounts for the high mortality rate in pancreatic cancer. Therefore, a better understanding of the mechanism(s) underlying the acquisition of the metastatic potential in pancreatic cancer is highly desirable. Methods: Microarray analysis in wild-type and highly liver metastatic human pancreatic cancer cell lines was performed to identify gene expression signatures that underlie the metastatic process. We validated our findings in patient samples, nude mice, cell lines and database analysis. Results: We identified a metastasis-related gene, laminin subunit alpha 4 (LAMA4), that was upregulated in highly liver metastatic human pancreatic cancer cell lines. Downregulation of LAMA4 reduced the liver metastatic ability of pancreatic cancer cells in vivo. Furthermore, LAMA4 expression was positively correlated with tumor severity and in silico analyses revealed that LAMA4 was associated with altered tumor microenvironment. In particular, our in vitro and in vivo results showed that LAMA4 expression was highly correlated with cancer-associated fibroblasts (CAFs) level which may contribute to pancreatic cancer metastasis. We further found that LAMA4 had a positive effect on the recruitment and activity of CAFs. Conclusions: These data provide evidence for LAMA4 as a possible biomarker of disease progression and poor prognosis in pancreatic cancer. Our findings indicate that LAMA4 may contribute to pancreatic cancer metastasis via recruitment or activation of CAFs.
Involvement of STAT5 in Oncogenesis
Biomedicines. 2020 Sep; 8(9): 316. doi: 10.3390/biomedicines8090316.
Clarissa Esmeralda Halim, Shuo Deng, Mei Shan Ong, and Celestial T. Yap
Abstract
Signal transducer and activator of transcription (STAT) proteins, and in particular STAT3, have been established as heavily implicated in cancer. Recently, the involvement of STAT5 signalling in the pathology of cancer has been shown to be of increasing importance. STAT5 plays a crucial role in the development of the mammary gland and the homeostasis of the immune system. However, in various cancers, aberrant STAT5 signalling promotes the expression of target genes, such as cyclin D, Bcl-2 and MMP-2, that result in increased cell proliferation, survival and metastasis. To target constitutive STAT5 signalling in cancers, there are several STAT5 inhibitors that can prevent STAT5 phosphorylation, dimerisation, or its transcriptional activity. Tyrosine kinase inhibitors (TKIs) that target molecules upstream of STAT5 could also be utilised. Consequently, since STAT5 contributes to tumour aggressiveness and cancer progression, inhibiting STAT5 constitutive activation in cancers that rely on its signalling makes for a promising targeted treatment option.
Sustained IKKβ Phosphorylation and NF-κB Activation by Superoxide-induced Peroxynitrite-mediated Nitrotyrosine Modification of B56γ3 and PP2A Inactivation
Redox Biology. 101834. doi: 10.1016/j.redox.2020.101834.
Yi HuiYee, Stephen Jun Fei Chong, Li RenKong, Boon Cher Goh, ShazibPervaiz
Abstract
Apart from its physiological role in inflammation and immunity, the nuclear factor-kappa B (NF-κB) protein complex has been implicated in tumorigenesis and its progression. Here, we provide evidence that a pro-oxidant milieu is an upstream effector of oncogenic NF-κB signaling. Through pharmacological or genetic inhibition of SOD1, we show that elevated intracellular superoxide (O2•-) mediates sustained IKK phosphorylation, and induces downstream degradation of IκBα, leading to the nuclear localization and transcriptional activation of NF-κB. Mechanistically, we show that such sustained NF-κB signaling is a function of protein phosphatase 2A (PP2A) inactivation brought about by the nitrative modification of its substrate-binding sub-unit B56γ. Importantly, the pro-oxidant driven NF-κB activation enhances the migratory and invasive potential of cancer cells. In summary, our work highlights the critical involvement of O2•–dependent peroxynitrite production in inhibiting PP2A-mediated dephosphorylation of IKK, thereby facilitating cancers to acquire an invasive phenotype. Given that NF-κB is a key player of chronic inflammation and carcinogenesis, our work unravels a novel synergistic node involving O2•–driven redox milieu and deregulated PP2A as a potential therapeutic target.
Project Coolbit: Can your watch predict heat stress and thermal comfort sensation?
Environmental Research Letters.
Negin Nazarian, Sijie Liu, Manon Kohler, Jason Kai Wei Lee, Clayton Miller, Winston TL Chow, Sharifah Badriyah Badriyah Alhadad, Alberto Martilli, Matias Quintana, Lindsey Sunden and Leslie Norford
Abstract
Global climate is changing as a result of anthropogenic warming, leading to higher daily excursions of temperature in cities. Such elevated temperatures have great implications on human thermal comfort and heat stress, which should be closely monitored. Current methods for heat exposure assessments (surveys, microclimate measurements, and laboratory experiments), however, present several limitations: measurements are scattered in time and space and data gathered on outdoor thermal stress and comfort often does not include physiological and behavioral parameters. To address these shortcomings, Project Coolbit aims to introduce a human-centric approach to thermal comfort assessments. In this study, we propose and evaluate the use of wrist-mounted wearable devices to monitor environmental and physiological responses that span a wide range of spatial and temporal distributions. We introduce an integrated wearable weather station that records a) microclimate parameters (such as air temperature and humidity), b) physiological parameters (heart rate, skin temperature and humidity), and c) subjective feedback. The feasibility of this methodology to assess thermal comfort and heat stress is then evaluated using two sets of experiments: controlled-environment physiological data collection, and outdoor environmental data collection. We find that using the data obtained through the wrist-mounted wearables, core temperature can be predicted non-invasively with 95 percent of target attainment (PTA) within 0.27C. Additionally, a direct connection between the air temperature at the wrist (Ta,w) and the perceived activity level (PAV) of individuals was drawn. We observe that with increased Ta,w, the desire for physical activity is significantly reduced, reaching “Transition only” PAV level at 36C. These assessments reveal that the wearable methodology provides a comprehensive and accurate representation of human heat exposure, which can be extended in real-time to cover a large spatial distribution in a given city and quantify the impact of heat exposure on human life.
Personal assessment of urban heat exposure: a systematic review
Environmental Research Letters.
Negin Nazarian and Jason Kai Wei Lee
Abstract
To fully address the multi-faceted challenges of urban heat, it is paramount that humans are placed at the center of the agenda. This is manifested in a recent shift in urban heat studies that aim to achieve a “Human-Centric” approach, i.e. focusing on personalized characteristics of comfort, well-being, performance, and health, as opposed to the one-size-fits-all solutions and guidelines. The proposed article is focused on systematically reviewing personalized urban heat studies and detailing the objectives posed, methodologies utilized, and limitations yet to be addressed. We further summarize current knowledge and challenges in addressing the impact of personal heat exposure on human life by discussing the literature linked with urban heat studies at the human, building, and city scales. Lastly, this systematic review reveals the need for future evaluations focused on accuracy and standardization of human-centric data collection and analytics, and more importantly, addressing critical geographic and socio-economic knowledge gaps identified in the field.
A Digital CRISPR-based Method for the Rapid Detection and Absolute Quantification of Viral Nucleic Acids.
MedRxiv. doi: 10.1101/2020.11.03.20223602.
Xiaolin Wu, Cheryl Chan, Yie Hou Lee, Stacy L. Springs, Timothy K. Lu, Hanry Yu
Abstract
Quantitative real-time PCR and CRISPR-based methods detect SARS-CoV-2 in 1 hour but do not allow for the absolute quantification of virus particles, which could reduce inter-lab variability and accelerate research. The 4-hour reaction time of the existing digital PCR-based method for absolute virus quantification is too long for widespread application. We report a RApid DIgital Crispr Approach (RADICA) for the absolute quantification of SARS-CoV-2 DNA and Epstein–Barr virus DNA in human samples that yields results within 1 hour. For validation, we compared RADICA to digital PCR for quantifying synthetic SARS-CoV-2 DNA and Epstein–Barr viral DNA. RADICA allows absolute quantification of DNA with a dynamic range from 0.6 to 2027 copies/µL (R2 value > 0.98), without cross-reactivity on similar virus or human background DNA. Thus, RADICA can accurately detect and quantify nucleic acid in 1h without thermal cycling, providing a 4-fold faster alternative to digital PCR-based virus detection.
EHMT2 epigenetically suppresses Wnt signaling and is a potential target in embryonal rhabdomyosarcoma
eLife 2020;9:e57683 doi: 10.7554/eLife.57683.
Ananya Pa, Jia Yu Leung, Gareth Chin Khye Ang, Vinay Kumar Rao, Luca Pignata, Huey Jin Lim, Maxime Hebrard, Kenneth TE Chang, Victor KM Lee, Ernesto Guccione, Reshma Taneja
Abstract
Wnt signaling is downregulated in embryonal rhabdomyosarcoma (ERMS) and contributes to the block of differentiation. Epigenetic mechanisms leading to its suppression are unknown and could pave the way toward novel therapeutic modalities. We demonstrate that EHMT2 suppresses canonical Wnt signaling by activating expression of the Wnt antagonist DKK1. Inhibition of EHMT2 expression or activity in human ERMS cell lines reduced DKK1 expression and elevated canonical Wnt signaling resulting in myogenic differentiation in vitro and in mouse xenograft models in vivo. Mechanistically, EHMT2 impacted Sp1 and p300 enrichment at the DKK1 promoter. The reduced tumor growth upon EHMT2 deficiency was reversed by recombinant DKK1 or LGK974, which also inhibits Wnt signaling. Consistently, among 13 drugs targeting chromatin modifiers, EHMT2 inhibitors were highly effective in reducing ERMS cell viability. Our study demonstrates that ERMS cells are vulnerable to EHMT2 inhibitors and suggest that targeting the EHMT2-DKK1-β-catenin node holds promise for differentiation therapy.
Directionalities of magnetic fields and topographic scaffolds synergise to enhance MSC chondrogenesis
Acta Biomaterilia. 2020 Oct 29;S1742-7061(20)30637-1. doi: 10.1016/j.actbio.2020.10.039.
Cenk Celik, Alfredo Franco-Obregón, Eng Hin Lee, James Hp Hui, Zheng Yang
Abstract
Mesenchymal stem cell (MSC) chondrogenesis is modulated by diverse biophysical cues. We have previously shown that brief, low-amplitude pulsed electromagnetic fields (PEMFs) differentially enhance MSC chondrogenesis in scaffold-free pellet cultures versus conventional tissue culture plastic (TCP), indicating an interplay between magnetism and micromechanical environment. Here, we examined the influence of PEMF directionality over the chondrogenic differentiation of MSCs laden on electrospun fibrous scaffolds of either random (RND) or aligned (ALN) orientations. Correlating MSCs’ chondrogenic outcome to pFAK activation and YAP localisation, MSCs on the RND scaffolds experienced the least amount of resting mechanical stress and underwent greatest chondrogenic differentiation in response to brief PEMF exposure (10 min at 1 mT) perpendicular to the dominant plane of the scaffolds (Z-directed). By contrast, in MSC-impregnated RND scaffold, greatest mitochondrial respiration resulted from X-directed PEMF exposure (parallel to the scaffold plane) and was associated with curtailed chondrogenesis. MSCs on TCP or the ALN scaffolds exhibited greater resting mechanical stress and accordingly, were unresponsive, or negatively responsive, to PEMF exposure from all directions. The efficacy of PEMF-induced MSC chondrogenesis is hence regulated in a multifaceted manner involving focal adhesion dynamics, as well as mitochondrial responses, culminating in a final cellular response. The combined contributions of micromechanical environment and magnetic field orientation hence will need to be considered when designing magnetic exposure paradigms.
Histone variants in skeletal myogenesis
Epigenetics. 2020 Aug 2;1-20. doi: 10.1080/15592294.2020.1795606.
Nandini Karthik, Reshma Taneja
Abstract
Histone variants regulate chromatin accessibility and gene transcription. Given their distinct properties and functions, histone varint substitutions allow for profound alteration of nucleosomal architecture and local chromatin landscape. Skeletal myogenesis driven by the key transcription factor MyoD is characterized by precise temporal regulation of myogenic genes. Timed substitution of variants within the nucleosomes provides a powerful means to ensure sequential expression of myogenic genes. Indeed, growing evidence has shown H3.3, H2A.Z, macroH2A, and H1b to be critical for skeletal myogenesis. However, the relative importance of various histone variants and their associated chaperones in myogenesis is not fully appreciated. In this review, we summarize the role that histone variants play in altering chromatin landscape to ensure proper muscle differentiation. The temporal regulation and cross talk between histones variants and their chaperones in conjunction with other forms of epigenetic regulation could be critical to understanding myogenesis and their involvement in myopathies.
Massively parallel single-molecule telomere length measurement with digital real-time PCR
Science Advances 21 Aug 2020: Vol. 6, no. 34, eabb7944. DOI: 10.1126/sciadv.abb7944
Yongqiang Luo, Ramya Viswanathan, Manoor Prakash Hande, Amos Hong Pheng Loh and Lih Feng Cheow
Abstract
Telomere length is a promising biomarker for age-associated diseases and cancer, but there are still substantial challenges to routine telomere analysis in clinics because of the lack of a simple and rapid yet scalable method for measurement. We developed the single telomere absolute-length rapid (STAR) assay, a novel high-throughput digital real-time PCR approach for rapidly measuring the absolute lengths and quantities of individual telomere molecules. We show that this technique provides the accuracy and sensitivity to uncover associations between telomere length distribution and telomere maintenance mechanisms in cancer cell lines and primary tumors. The results indicate that the STAR assay is a powerful tool to enable the use of telomere length distribution as a biomarker in disease and population-wide studies.
Use of digital platform to encourage good laboratory practices during departmental safety inspections
Yeong Bing Ong, Uma Thambiayah, Phoebe Kang Sheing Koh, Nurulhuda Mohamed Nassir, Hooi Ling Wong, Manoor Prakash Hande
Abstract
Routine safety inspections were conducted in our department to check that the laboratories meet the legal requirements set by authorities on workplace safety and health. However, recurring undesirable laboratory practices were observed during monthly laboratory safety inspections. Our Department Safety and Health Committee installed a platform to allocate points to good laboratory practices observed and reward the best performing laboratories to encourage conversion of these good practices into good laboratory habits. Using digital platforms like Microsoft Forms and Planner, the inspectors were able to conduct laboratory inspections and to document the findings in a clear, transparent and readily accessible manner. The findings were analysed by all the safety leads in the different laboratories to facilitate the rectification of the safety issues. Laboratories with best performances during the inspection were rewarded for their consistent hard work. Such approaches encouraged good laboratory practices in our department and hopefully, will facilitate sustaining good safety culture in the future.
Thermoregulatory responses to ice slurry ingestion during low and moderate intensity exercises with restrictive heat loss
J Sci Med Sport. 2020 Jul 15;S1440-2440(20)30685-X. doi: 10.1016/j.jsams.2020.07.002.
Sharifah B Alhadad, Ivan C C Low, Jason K W Lee
Abstract
Objectives
We investigated the thermoregulatory responses to ice slurry ingestion during low- and moderate-intensity exercises with restrictive heat loss.
Design
Randomised, counterbalanced, cross-over design.
Methods
Following a familiarisation trial, ten physically active males exercised on a motorised treadmill at low-intensity (L; 40% VO 2max) or moderate-intensity (M; 70% VO 2max) for 75-min, in four randomised, counterbalanced trials. Throughout the exercise bout, participants donned a raincoat to restrict heat loss. Participants ingested 2 g kg −1 body mass of ambient water (L + AMB and M + AMB trials) or ice slurry (L + ICE and M + ICE trials) at 15-min intervals during exercise in environmental conditions of T db, 25.1 ± 0.6 °C and RH, 63 ± 5%. Heart rate (HR), gastrointestinal temperature (T gi), mean weighted skin temperature (T sk), estimated sweat loss, ratings of perceived exertion (RPE) and thermal sensation (RTS) were recorded.
Results
Compared to L + AMB, participants completed L + ICE trials with lower ΔT gi (0.8 ± 0.3°C vs 0.6 ± 0.2 °C; p = 0.03), mean RPE (10 ± 1 vs 9 ± 1; p = 0.03) and estimated sweat loss (0.91 ± 0.2 L vs 0.78 ± 0.27 L; p = 0.04). Contrastingly, T gi (p = 0.22), T sk (p = 0.37), HR (p = 0.31), RPE (p = 0.38) and sweat loss (p = 0.17) were similar between M + AMB and M + ICE trials. RTS was similar during both low-intensity (4.9 ± 0.5 vs 4.7 ± 0.3; p = 0.10) and moderate-intensity exercise (5.3 ± 0.47 vs 5.0 ± 0.4; p = 0.09).
Conclusions
Per-cooling using ice slurry ingestion marginally reduced thermal strain during low-intensity but not during moderate-intensity exercise. Ice slurry may be an effective and practical heat mitigation strategy during low-intensity exercise such as in occupational and military settings, but a greater volume should be considered to ensure its efficacy.
Patients’ and healthcare professionals’ perspectives towards technology-assisted diabetes self-management education. A qualitative systematic review
PLoS One. 2020 Aug 17;15(8):e0237647. doi: 10.1371/journal.pone.0237647. eCollection 2020.
Sneha Rajiv Jain, Yuan Sui, Cheng Han Ng, Zhi Xiong Chen, Lay Hoon Goh, Shefaly Shorey
Abstract
Introduction
Diabetes self-management education is a key aspect in the long-term management of type 2 diabetes. The patient and healthcare professional (HCP) perspective on the use of technology-assisted DSME has yet to be studied. Hence, the objective of this study was to better understand the factors that facilitate or hinder the adoptions of such education by adults with type 2 diabetes and their HCPs.
Methods
We systematically searched five databases (Medline, Embase, CINAHL, Web of Science Core Collection, and PsycINFO) until August 2019. The search included qualitative and mixed-method studies that reported the views of patients and HCPs regarding features, uses, and implementations of technology-assisted DSME. Data were synthesized through an inductive thematic analysis.
Results
A total of 13 articles were included, involving 242 patients, ranging from 18 to 81 years and included web-based, mobile application, digital versatile disc (DVD), virtual reality or telehealth interventions. Patients and HCPs had mixed views towards features of the technology-assisted interventions, with patients’ personal qualities and HCPs’ concerns affecting uses of the interventions. Patients generally preferred technologies that were easy to access, use, and apply and that had reliable information. Patients’ ambitions motivated them, and personal attributes such as poor competence with technology, poor literacy, and language barriers acted as barriers. Patients especially liked the peer support that they received but did not like it when there was no regulation of advice on these platforms. HCPs believed that while the interventions were useful to patients, they faced difficulties with integration into their clinical workflows.
Conclusion
This review explored the features of technology-assisted diabetes self-management education interventions that enhanced positive patient engagements and the negative aspects of both the platforms and the target groups. Technical support and training will be effective in managing these concerns and ensuring meaningful use of these platforms.
Neuroblastoma patient-derived cultures are enriched for a mesenchymal gene signature and reflect individual drug response
Cancer Sci. 2020 Aug 10. doi: 10.1111/cas.14610.
Esther Hee, Meng Kang Wong, Sheng Hui Tan, Zhang’E Choo, Chik Hong Kuick, Sharon Ling, Min Hwee Yong, Sudhanshi Jain, Derrick W Q Lian, Eileen H Q Ng, Yvonne F L Yong, Mee Hiong Ren, Nurfarhanah Syed Sulaiman, Sharon Y Y Low, Yong Wei Chua, Muhammad Fahmy Syed, Tony K H Lim, Shui Yen Soh, Prasad Iyer, Michaela S F Seng, Joyce C M Lam, Enrica E K Tan, Mei Yoke Chan, Ah Moy Tan, Yong Chen, Zhixiong Chen, Kenneth T E Chang, Amos Hong Pheng Loh
Abstract
Ex vivo evaluation of personalized models can facilitate individualized treatment selection for patients, and advance the discovery of novel therapeutic options. However, for embryonal malignancies, representative primary cultures have been difficult to establish. We developed patient‐derived cell cultures (PDCs) from chemo‐naïve and post–treatment neuroblastoma tumors in a consistent and efficient manner, and characterized their in vitro growth dynamics, histomorphology, gene expression, and functional chemo‐response. From 34 neuroblastoma tumors, 22 engrafted in vitro to generate 31 individual PDC lines, with higher engraftment seen with metastatic tumors. PDCs displayed characteristic immunohistochemical staining patterns of PHOX2B, TH, and GD2 synthase. Concordance of MYCN amplification, 1p and 11q deletion between PDCs and patient tumors was 83.3%, 72.7%, and 80.0% respectively. PDCs displayed a predominantly mesenchymal‐type gene expression signature and showed upregulation of pro‐angiogenic factors that were similarly enriched in culture medium and paired patient serum samples. When tested with standard‐of‐care cytotoxics at human Cmax‐equivalent concentrations, MYCN‐amplified and non‐MYCN‐amplified PDCs showed a differential response to cyclophosphamide and topotecan, which mirrored the corresponding patients’ responses, and correlated with gene signatures of chemosensitivity. In this translational proof‐of‐concept study, early‐phase neuroblastoma PDCs enriched for the mesenchymal cell subpopulation recapitulated the individual molecular and phenotypic profile of patient tumors, and highlighted their potential as a platform for individualized ex vivo drug‐response testing.
Biomimicking Fiber Platform with Tunable Stiffness to Study Mechanotransduction Reveals Stiffness Enhances Oligodendrocyte Differentiation but Impedes Myelination through YAP-Dependent
Small. 2020 Aug 12;e2003656. doi: 10.1002/smll.202003656.
William Ong, Nicolas Marinval, Junquan Lin, Mui Hoon Nai, Yee-Song Chong, Coline Pinese, Sreedharan Sajikumar, Chwee Teck Lim, Charles Ffrench-Constant, Marie E Bechler, Sing Yian Chew
Abstract
A key hallmark of many diseases, especially those in the central nervous system (CNS), is the change in tissue stiffness due to inflammation and scarring. However, how such changes in microenvironment affect the regenerative process remains poorly understood. Here, a biomimicking fiber platform that provides independent variation of fiber structural and intrinsic stiffness is reported. To demonstrate the functionality of these constructs as a mechanotransduction study platform, these substrates are utilized as artificial axons and the effects of axon structural versus intrinsic stiffness on CNS myelination are independently analyzed. While studies have shown that substrate stiffness affects oligodendrocyte differentiation, the effects of mechanical stiffness on the final functional state of oligodendrocyte (i.e., myelination) has not been shown prior to this. Here, it is demonstrated that a stiff mechanical microenvironment impedes oligodendrocyte myelination, independently and distinctively from oligodendrocyte differentiation. Yes-associated protein is identified to be involved in influencing oligodendrocyte myelination through mechanotransduction. The opposing effects on oligodendrocyte differentiation and myelination provide important implications for current work screening for promyelinating drugs, since these efforts have focused mainly on promoting oligodendrocyte differentiation. Thus, the platform may have considerable utility as part of a drug discovery program in identifying molecules that promote both differentiation and myelination.
Anti-malarial drug, artemisinin and its derivatives for the treatment of respiratory diseases
Pharmacol Res. 2020 Aug;158:104901. doi: 10.1016/j.phrs.2020.104901.
Dorothy H J Cheong, Daniel W S Tan, Fred W S Wong, Thai Tran
Abstract
Artemisinins are sesquiterpene lactones with a peroxide moiety that are isolated from the herb Artemisia annua. It has been used for centuries for the treatment of fever and chills, and has been recently approved for the treatment of malaria due to its endoperoxidase properties. Progressively, research has found that artemisinins displayed multiple pharmacological actions against inflammation, viral infections, and cell and tumour proliferation, making it effective against diseases. Moreover, it has displayed a relatively safe toxicity profile. The use of artemisinins against different respiratory diseases has been investigated in lung cancer models and inflammatory-driven respiratory disorders. These studies revealed the ability of artemisinins in attenuating proliferation, inflammation, invasion, and metastasis, and in inducing apoptosis. Artemisinins can regulate the expression of pro-inflammatory cytokines, nuclear factor-kappa B (NF-κB), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), promote cell cycle arrest, drive reactive oxygen species (ROS) production and induce Bak or Bax-dependent or independent apoptosis. In this review, we aim to provide a comprehensive update of the current knowledge of the effects of artemisinins in relation to respiratory diseases to identify gaps that need to be filled in the course of repurposing artemisinins for the treatment of respiratory diseases. In addition, we postulate whether artemisinins can also be repurposed for the treatment of COVID-19 given its anti-viral and anti-inflammatory properties.
<h2MicroRNAs in chronic airway diseases: Clinical correlation and translational applications
Pharmacol Res. 2020 Jun 23;160:105045. doi: 10.1016/j.phrs.2020.105045.
Bryce W Q Tan, Wei Liang Sim, Jit Kong Cheong, Win Sen Kuan, Thai Tran, Hui Fang Lim
Abstract
MicroRNAs (miRNAs) are short single-stranded RNAs that have pivotal roles in disease pathophysiology through transcriptional and translational modulation of important genes. It has been implicated in the development of many diseases, such as stroke, cardiovascular conditions, cancers and inflammatory airway diseases. There is recent evidence that miRNAs play important roles in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD), and could help to distinguish between T2-low (non-eosinophilic, steroid-insensitive) versus T2-high (eosinophilic, steroid-sensitive) disease endotypes. As these are the two most prevalent chronic respiratory diseases globally, with rising disease burden, miRNA research might lead to the development of new diagnostic and therapeutic targets. Research involving miRNAs in airway disease is challenging because: (i) asthma and COPD are heterogeneous inflammatory airway diseases; there are overlapping but distinct inter- and intra-disease differences in the immunological pathophysiology, (ii) there exists more than 2000 known miRNAs and a single miRNA can regulate multiple targets, (iii) differential effects of miRNAs could be present in different cellular subtypes and tissues, and (iv) dysregulated miRNA expression might be a direct consequence of an indirect effect of airway disease onset or progression. As miRNAs are actively secreted in fluids and remain relatively stable, they have the potential for biomarker development and therapeutic targets. In this review, we summarize the preclinical data on potential miRNA biomarkers that mediate different pathophysiological mechanisms in airway disease. We discuss the framework for biomarker development using miRNA and highlight the need for careful patient characterization and endotyping in the screening and validation cohorts, profiling both airway and blood samples to determine the biological fluids of choice in different disease states or severity, and adopting an untargeted approach. Collaboration between the various stakeholders – pharmaceutical companies, laboratory professionals and clinician-scientists is crucial to reduce the difficulties and cost required to bring miRNA research into the translational stage for airway diseases.
Decellularized liver as a translucent ex vivo model for vascular embolization evaluation
Biomaterials. 2020 May;240:119855. doi: 10.1016/j.biomaterials.2020.119855.
Yanan Gao, Zhihua Li, Yin Hong, Tingting Li, Xiaoyan Hu, Luyao Sun, Zhengchang Chen, Zijian Chen, Zhiheng Luo, Xin Wang, Jian Kong, Guanglei Li, Hsing-Lin Wang, Hwa Liang Leo, Hanry Yu, Lei Xi, Qiongyu Guo
Abstract
Transarterial chemoembolization (TACE) is the preferred treatment for patients with unresectable intermediate stage hepatocellular carcinoma, however currently the development of embolic agents for TACE lacks in vitro models that closely represent the sophisticated features of the organ and the vascular systems therein. In this study, we presented a new strategy using an ex vivo liver model to provide a translucent template for evaluating embolic agents of TACE. The ex vivo liver model was developed through decellularizion of rat liver organs with preserved liver-specific vasculatures and improved transmittance of the whole liver up to 23% at 550 nm. Using this model, we investigated the embolization performances of both liquid and particle-based embolic agents, including penetration depth, embolization end-points, injection pressure and spatial distribution dynamics. We found that the embolization endpoint of liquid embolic agent such as ethiodised oil was strongly dependent on the injection pressure, and the pressure quickly built up when reaching the capillary endings, which could cause embolic agent leaking and potential tissue damages. In contrast, for particle-based embolic agents such as poly-dl-lactide microparticles and CalliSpheres® beads, their embolization endpoints were mainly determined by the particle size, whereas the particle densities close to the endpoints dramatically dropped down, which with the penetration depth represented two critical factors determining the embolic distribution. Such a decellularized organ model may open a new route to visually and quantitatively characterize embolization effects of various embolotherapies.
Bile canaliculi contract autonomously by releasing calcium into hepatocytes via mechanosensitive calcium channel
Biomaterials. 2020 Aug 11;259:120283. doi: 10.1016/j.biomaterials.2020.120283.
Kapish Gupta, Inn Chuan Ng, Gowri Manohari Balachander, Binh P Nguyen, Lisa Tucker-Kellogg, Boon Chuan Low, Hanry Yu
Abstract
Drug-induced hepatocellular cholestasis leads to altered bile flow. Bile is propelled along the bile canaliculi (BC) by actomyosin contractility, triggered by increased intracellular calcium (Ca2+). However, the source of increased intracellular Ca2+ and its relationship to transporter activity remains elusive. We identify the source of the intracellular Ca2+ involved in triggering BC contractions, and we elucidate how biliary pressure regulates Ca2+ homeostasis and associated BC contractions. Primary rat hepatocytes were cultured in collagen sandwich. Intra-canalicular Ca2+ was measured with fluo-8; and intra-cellular Ca2+ was measured with GCaMP. Pharmacological modulators of canonical Ca2+-channels were used to study the Ca2+-mediated regulation of BC contraction. BC contraction correlates with cyclic transfer of Ca2+ from BC to adjacent hepatocytes, and not with endoplasmic reticulum Ca2+. A mechanosensitive Ca2+ channel (MCC), Piezo-1, is preferentially localized at BC membranes. The Piezo-1 inhibitor GsMTx-4 blocks the Ca2+ transfer, resulting in cholestatic generation of BC-derived vesicles whereas Piezo-1 hyper-activation by Yoda1 increases the frequency of Ca2+ transfer and BC contraction cycles. Yoda1 can recover normal BC contractility in drug-induced hepatocellular cholestasis, supporting that Piezo-1 regulates BC contraction cycles. Finally, we show that hyper-activating Piezo-1 can be exploited to normalize bile flow in drug-induced hepatocellular cholestasis.
COVID-19 and thermoregulation-related problems: Practical recommendations
Temperature. 2020. doi: 10.1080/23328940.2020.1790971.
Hein Daanen, Stephan Bose-O’Reilly, Matt Brearley, D. Andreas Flouris, Nicola M. Gerrett, Maud Huynen, Hunter M. Jones, Jason Kai Wei Lee, Nathan Morris, Ian Norton , Lars Nybo, Elspeth Oppermann, Joy Shumake-Guillemot & Peter Van den Hazel
Abstract
The COVID-19 pandemic started in the cold months of the year 2020 in the Northern hemisphere. Concerns were raised that the hot season may lead to additional problems as some typical interventions to prevent heat-related illness could potentially conflict with precautions to reduce coronavirus transmission. Therefore, an international research team organized by the Global Health Heat Information Network generated an inventory of the specific concerns about this nexus and began to address the issues. Three key thermal and covid-19 related topics were highlighted: 1) For the general public, going to public cool areas in the hot season interferes with the recommendation to stay at home to reduce the spread of the virus. Conflicting advice makes it necessary to revise national heat plans and alert policymakers of this forecasted issue. 2) For medical personnel working in hot conditions, heat strain is exacerbated due to a reduction in heat loss from wearing personal protective equipment to prevent contamination. To avoid heat-related injuries, medical personnel are recommended to precool and to minimize the increase in body core temperature using adopted work/rest schedules, specific clothing systems, and by drinking cold fluids. 3) Fever, one of the main symptoms of COVID-19, may be difficult to distinguish from heat-induced hyperthermia and a resting period may be necessary prior to measurement to avoid misinterpretation. In summary, heat in combination with the COVID-19 pandemic leads to additional problems; the impact of which can be reduced by revising heat plans and implementing special measures attentive to these compound risks.
Role of Histone Deacetylases in Skeletal Muscle Physiology and Systemic Energy Homeostasis: Implications for Metabolic Diseases and Therapy
Front Physiol. 2020 Aug 11;11:949. doi: 10.3389/fphys.2020.00949. eCollection 2020.
Haili Tian, Sujuan Liu, Jun Ren, Jason Kai Wei Lee, Ru Wang, Peijie Chen
Abstract
Skeletal muscle is the largest metabolic organ in the human body and is able to rapidly adapt to drastic changes during exercise. Histone acetyltransferases (HATs) and histone deacetylases (HDACs), which target histone and non-histone proteins, are two major enzyme families that control the biological process of histone acetylation and deacetylation. Balance between these two enzymes serves as an essential element for gene expression and metabolic and physiological function. Genetic KO/TG murine models reveal that HDACs possess pivotal roles in maintaining skeletal muscles’ metabolic homeostasis, regulating skeletal muscles motor adaptation and exercise capacity. HDACs may be involved in mitochondrial remodeling, insulin sensitivity regulation, turn on/off of metabolic fuel switching and orchestrating physiological homeostasis of skeletal muscles from the process of myogenesis. Moreover, many myogenic factors and metabolic factors are modulated by HDACs. HDACs are considered as therapeutic targets in clinical research for treatment of cancer, inflammation, and neurological and metabolic-related diseases. This review will focus on physiological function of HDACs in skeletal muscles and provide new ideas for the treatment of metabolic diseases.
Peroxynitrite promotes serine-62 phosphorylation-dependent stabilization of the oncoprotein c-Myc
Redox Biol. 2020 Jul; 34: 101587. doi: 10.1016/j.redox.2020.101587
Deepika Raman, Stephen J.F. Chong, Kartini Iskandar, Jayshree L. Hirpara, and Shazib Pervaiz
Abstract
Stabilization of c-Myc oncoprotein is dependent on post-translational modifications, especially its phosphorylation at serine-62 (S62), which enhances its tumorigenic potential. Herein we report that increase in intracellular superoxide induces phospho-stabilization and activation of c-Myc in cancer cells. Importantly, sustained phospho-S62 c-Myc was necessary for promoting superoxide dependent chemoresistance as non-phosphorylatable S62A c-Myc was insensitive to the redox impact when subjected to chemotherapeutic insults. This redox-dependent sustained S62 phosphorylation occurs through nitrative inhibition of phosphatase, PP2A, brought about by peroxynitrite, a reaction product of superoxide and nitric oxide. We identified a conserved tyrosine residue (Y238) in the c-Myc targeting subunit B56α of PP2A, which is selectively amenable to nitrative inhibition, further preventing holoenzyme assembly. In summary, we have established a novel mechanism wherein the pro-oxidant microenvironment stimulates a pro-survival milieu and reinforces tumor maintenance as a functional consequence of c-Myc activation through its sustained S62 phosphorylation via inhibition of phosphatase PP2A.
Redox signaling in the pathogenesis of human disease and the regulatory role of autophagy
Int Rev Cell Mol Biol. 2020;352:189-214. doi: 10.1016/bs.ircmb.2020.03.002.
Shazib Pervaiz, Gregory L Bellot, Antoinette Lemoin, Catherine Brenner
Abstract
Aberrant cell death signaling and oxidative stress are implicated in myriad of human pathological states such as neurodegenerative, cardiovascular, metabolic and liver diseases, as well as drug-induced toxicities. While regulated cell death and mild oxidative stress are essential during normal tissue homeostasis, deregulated signaling can trigger massive depletion in a particular cell type and/or damage tissues and impair organ function with deleterious consequences that manifest as disease states. If regeneration cannot restore tissue homeostasis, the severity of the disease correlates with the extent of cell loss. Cell death can be executed via multiple modalities such as apoptosis, necrosis, pyroptosis, necroptosis and ferroptosis, depending on cell autonomous mechanisms (e.g., reactive oxygen species production, calcium overload and altered proteostasis) and/or non-cell autonomous processes (e.g., environmental stress, irradiation, chemotherapeutic agents, inflammation and pathogens). Accordingly, the inhibition of aberrant cell death and oxidative stress together with activation of autophagy, a regulated self-degradation process, are progressively emerging as relevant cytoprotective strategies to sustain homeostasis. In this review, we summarize the current literature on the crosstalk between cellular redox state and cell fate signaling, specifically from the standpoint of autophagy and its role in the maintenance of tissue/organ homeostasis via regulating oxidative stress and the potential implications for the design of novel therapeutic strategies.
Noncanonical Cell Fate Regulation by Bcl-2 Proteins
Trends Cell Biol. 2020 Jul;30(7):537-555. doi: 10.1016/j.tcb.2020.03.004.
Stephen Jun Fei Chong, Saverio Marchi, Giulia Petroni, Guido Kroemer, Lorenzo Galluzzi, Shazib Pervaiz
Abstract
Bcl-2 proteins are widely known as key controllers of mitochondrial outer membrane permeabilization, arguably the most important step of intrinsic apoptosis. Accumulating evidence indicate that most, if not all, members of the Bcl-2 protein family also mediate a number of apoptosis-unrelated functions. Intriguingly, many of these functions ultimately impinge on cell fate decisions via apoptosis-dependent or -independent mechanisms, delineating a complex network through which Bcl-2 family members regulate cell survival and death. Here, we critically discuss the mechanisms through which Bcl-2 proteins influence cell fate as they regulate autophagy, cellular senescence, inflammation, bioenergetic metabolism, Ca2+ fluxes, and redox homeostasis.
Targeting Mitochondrial Apoptosis to Overcome Treatment Resistance in Cancer
Cancers (Basel). 2020 Mar 2;12(3):574. doi: 10.3390/cancers12030574.
Natalie Yan Li Ngoi, Clarice Choong, Joanne Lee, Gregory Bellot, Andrea Li Ann Wong, Boon Cher Goh, Shazib Pervaiz
Abstract
Deregulated cellular apoptosis is a hallmark of cancer and chemotherapy resistance. The B-cell lymphoma 2 (BCL-2) protein family members are sentinel molecules that regulate the mitochondrial apoptosis machinery and arbitrate cell fate through a delicate balance between pro- and anti-apoptotic factors. The recognition of the anti-apoptotic BCL2 gene as an oncogenic driver in hematological malignancies has directed attention toward unraveling the biological significance of each of the BCL-2 superfamily members in cancer progression and garnered interest in the targeting of apoptosis in cancer therapy. Accordingly, the approval of venetoclax (ABT-199), a small molecule BCL-2 inhibitor, in patients with chronic lymphocytic leukemia and acute myeloid leukemia has become the proverbial torchbearer for novel candidate drug approaches selectively targeting the BCL-2 superfamily. Despite the inspiring advances in this field, much remains to be learned regarding the optimal therapeutic context for BCL-2 targeting. Functional assays, such as through BH3 profiling, may facilitate prediction of treatment response, development of drug resistance and shed light on rational combinations of BCL-2 inhibitors with other branches of cancer therapy. This review summarizes the pathological roles of the BCL-2 family members in cancer, discusses the current landscape of their targeting in clinical practice, and highlights the potential for future therapeutic inroads in this important area.
Cell‐Derived Vesicles as TRPC1 Channel Delivery Systems for the Recovery of Cellular Respiratory and Proliferative Capacities
Advanced Biosystems. doi: 10.1002/adbi.202000146
Felix Kurth, Yee Kit Tai, Dinesh Parate, Marc van Oostrum, Yannick R. F. Schmid, Shi Jie Toh, Jasmine Lye Yee Yap, Bernd Wollscheid, Alaa Othman, Petra S. Dittrich, Alfredo Franco‐Obregón
Abstract
Pulsed electromagnetic fields (PEMFs) are capable of specifically activating a TRPC1‐mitochondrial axis underlying cell expansion and mitohormetic survival adaptations. This study characterizes cell‐derived vesicles (CDVs) generated from C2C12 murine myoblasts and shows that they are equipped with the sufficient molecular machinery to confer mitochondrial respiratory capacity and associated proliferative responses upon their fusion with recipient cells. CDVs derived from wild type C2C12 myoblasts include the cation‐permeable transient receptor potential (TRP) channels, TRPC1 and TRPA1, and directly respond to PEMF exposure with TRPC1‐mediated calcium entry. By contrast, CDVs derived from C2C12 muscle cells in which TRPC1 has been genetically knocked‐down using CRISPR/Cas9 genome editing, do not. Wild type C2C12‐derived CDVs are also capable of restoring PEMF‐induced proliferative and mitochondrial activation in two C2C12‐derived TRPC1 knockdown clonal cell lines in accordance to their endogenous degree of TRPC1 suppression. C2C12 wild type CDVs respond to menthol with calcium entry and accumulation, likewise verifying TRPA1 functional gating and further corroborating compartmental integrity. Proteomic and lipidomic analyses confirm the surface membrane origin of the CDVs providing an initial indication of the minimal cellular machinery required to recover mitochondrial function. CDVs hence possess the potential of restoring respiratory and proliferative capacities to senescent cells and tissues.
A vascular-liver chip for sensitive detection of nutraceutical metabolites from human pluripotent stem cell derivatives
Biomicrofluidics 14, 034108. doi: 10.1063/5.0004286
Fang Yu, Yeek Teck Goh, Huan Li, Narmada Balakrishnan Chakrapani, Ming Ni, Guo Lin Xu, Tseng-Ming Hsieh, Yi-Chin Toh, Christine Cheung, Ciprian Iliescu, and Hanry Yu
Abstract
Human pluripotent stem cell (hPSC) is a great resource for generating cell derivatives for drug efficiency testing. Metabolites of nutraceuticals can exert anti-inflammatory effects on blood vessels. However, the concentration of nutraceutical metabolites produced in hPSC-derived hepatocytes (hPSC-HEPs) is usually low. To enable the detection of these metabolites under the in vitro environment, we have developed a co-culture model consisting of parallel co-culture chambers and a recirculating microfluidic system with minimum fluid volume, optimal cell culture environment. The model allows cells to be exposed continuously to nutraceutical metabolites. In this perfused culturing model, hPSC-derived endothelial cells and hPSC-HEPs are co-cultured without physical contact. When an anti-inflammatory nutraceutical, quercetin, was administrated to the co-culture, higher levels of quercetin metabolites were detected on-chip compared with static control. We further induced inflammation with Interleukin-1β in the co-culture model and measured interleukin 8 (IL-8) generation. The IL-8 level was suppressed more significantly by quercetin metabolites in the perfusion co-culture, as compared to static culture. This is due to enhanced metabolites production on-chip. This microfluidic co-culture model enables in vitro screening of nutraceuticals using hPSC-derived cells.
Functional Stem Cell Sorting via Integrative Droplet Synchronization
Guoyun Sun, Yao Teng, Zixuan Zhao, Lih Feng Cheow, Hanry Yu, Chia-Hung Chen
Abstract
Stem cell regenerative medicine strategy requires selecting functional cells to trigger repair processes. Stem cell secretion measurement is important to evaluate cellular activities for functional cell sorting. At present, to determine single cell secretions, mixing chemical sensors and cells together in a chamber is a standard procedure. However, toxic chemical sensors, such as albumin assay kits, are used during this process, causing low viability (64%) and low functionality (30%). It is especially important for stem cell profiling, as the toxicity of chemical sensors such as albumin permanently changes stem cell phenotypes, leading to unwanted analysis outcomes. Moreover, because of the sensor toxicity, the challenge of culturing sorted cells remain. In this study, an integrative synchronized droplet screen system was developed to separate a large droplet with cell encapsulation into two daughter droplets: one droplet containing cell secretions and the other droplet containing a single cell. These two daughter droplets moved along the channels at the same speed in synchronization. By injecting toxic chemical sensors into one daughter droplet, the single-cell secretions were determined without affecting the cells in the corresponding droplet. Based on the daughter droplet synchronization, the cells without mixing toxicity sensors were sorted for cell culturing. For example, to identify hepatocytes, the albumin secretion of undifferentiated HepaRG stem cells was measured in daughter droplets by injecting a toxic albumin assay kit for functional stem cell sorting. With synchronized sorting, functional hepatocytes were collected without exposure to toxic chemical sensors, showing high viability (78%) and active functionality (89%).
Biomimetic Niches Reveal the Minimal Cues to Trigger Apical Lumen Formation in Single Hepatocytes
Nature Materials. 2020 Apr 27. doi: 10.1038/s41563-020-0662-3. Online ahead of print.
Yue Zhang, Richard De Mets, Cornelia Monzel, Vidhyalakshmi Acharya, Pearlyn Toh, Jasmine Fei Li Chin, Noémi Van Hul, Inn Chuan Ng, Hanry Yu, Soon Seng Ng, S Tamir Rashid, Virgile Viasnoff
Abstract
The symmetry breaking of protein distribution and cytoskeleton organization is an essential aspect for the development of apicobasal polarity. In embryonic cells this process is largely cell autonomous, while differentiated epithelial cells collectively polarize during epithelium formation. Here, we demonstrate that the de novo polarization of mature hepatocytes does not require the synchronized development of apical poles on neighbouring cells. De novo polarization at the single-cell level by mere contact with the extracellular matrix and immobilized cadherin defining a polarizing axis. The creation of these single-cell liver hemi-canaliculi allows unprecedented imaging resolution and control and over the lumenogenesis process. We show that the density and localization of cadherins along the initial cell-cell contact act as key triggers of the reorganization from lateral to apical actin cortex. The minimal cues necessary to trigger the polarization of hepatocytes enable them to develop asymmetric lumens with ectopic epithelial cells originating from the kidney, breast or colon.
Pathophysiological Mechanisms by Which Heat Stress Potentially Induces Kidney Inflammation and Chronic Kidney Disease in Sugarcane Workers
Nutrients. 2020 Jun 2;12(6):E1639. doi: 10.3390/nu12061639.
Erik Hansson, Jason Glaser, Kristina Jakobsson, Ilana Weiss, Catarina Wesseling, Rebekah A I Lucas, Jason Lee Kai Wei, Ulf Ekström, Julia Wijkström, Theo Bodin, Richard J Johnson, David H Wegman
Abstract
Background: Chronic kidney disease of non-traditional origin (CKDnt) is common among Mesoamerican sugarcane workers. Recurrent heat stress and dehydration is a leading hypothesis. Evidence indicate a key role of inflammation.
Methods: Starting in sports and heat pathophysiology literature, we develop a theoretical framework of how strenuous work in heat could induce kidney inflammation. We describe the release of pro-inflammatory substances from a leaky gut and/or injured muscle, alone or in combination with tubular fructose and uric acid, aggravation by reduced renal blood flow and increased tubular metabolic demands. Then, we analyze longitudinal data from >800 sugarcane cutters followed across harvest and review the CKDnt literature to assess empirical support of the theoretical framework.
Results: Inflammation (CRP elevation and fever) and hyperuricemia was tightly linked to kidney injury. Rehydrating with sugary liquids and NSAID intake increased the risk of kidney injury, whereas electrolyte solution consumption was protective. Hypokalemia and hypomagnesemia were associated with kidney injury.
Discussion: Heat stress, muscle injury, reduced renal blood flow and fructose metabolism may induce kidney inflammation, the successful resolution of which may be impaired by daily repeating pro-inflammatory triggers. We outline further descriptive, experimental and intervention studies addressing the factors identified in this study.
Climate Change, Occupational Heat Stress, Human Health and Socio-Economic Factors
Handbook of Socioeconomic Determinants of Occupational Health pp 1-19
T. Kjellstrom, E. Oppermann, J. K. W. Lee
Abstract
Workplace heat is an important occupational health hazard. It has attracted new attention in recent years due to ongoing climate change and projections of future increases of heat in most parts of the world. This chapter provides an overview of the physiological basis for this occupational health hazard and related serious health and social effects that may develop. While outdoor jobs in the sun create particular risks, many millions of workers in factories in tropical areas are also exposed to excessive heat because effective air-conditioning cooling systems are not installed. Excessive heat exposure in workplaces can cause heat exhaustion and heat stroke unless the worker is able to take action to reduce thermal strain, such as by reducing work intensity or taking frequent breaks. These protective actions reduce health risk and affect hourly productivity and the economic output from the work done.
The social and economic factors that contribute to health risks include social norms and attitudes concerning basic low-skill work that is particularly risky in hot situations. Gender-based employment also has implications for occupational heat-health risk given sex-based differences in vulnerability to heat. For instance, some physically intensive jobs are traditionally very male-focused, and mass production garment works in hot factories of tropical areas are very female-focused. In some ways women are more sensitive to heat, and pregnancy is a period of particular heat exposure risks. The workforce in many countries is ageing, and older people are more vulnerable to heat than younger people. Another risk group is migrant workers who often are provided with little occupational health protection. The increased risk of health impacts also has important social and economic impacts, such as reduced daily income, when heat slows work output. At the community level, the increasing heat due to climate change can also undermine traditional customs and degrade social well-being. Our analysis indicates the need to develop policies that limit the ongoing heat increase due to climate change and to implement protection in situations of excessive heat.
Evaluating the Effectiveness of Labor Protection Policy on Occupational Injuries Caused by Extreme Heat in a Large Subtropical City of China
Yanan Su, Liangliang Cheng, Wenjia Cai, Jason Kai Wei Lee, Shuang Zhong, Siyu Chen, Teng Li, Xinfei Huang, Cunrui Huang
Abstract
On March 1, 2012, the Chinese government implemented the Administrative Measures on Heatstroke Prevention (AMHP2012) to combat the occupational health impacts of extreme heat, and reducing occupational injury was one of the main purposes. This study aimed at quantifying the intervention effects of the AMHP2012 on extreme heat-related occupational injuries and subsequent insurance payouts in Guangzhou, China. Data on occupational injuries and insurance payouts were collected from March 1, 2011, to February 28, 2013, from the occupational injury insurance system of Guangzhou. A quasi-experimental design with before-after control was adopted. Interrupted time series analysis was performed to quantify the change of occupational injuries and insurance payouts after policy implementation. The distributed lag non-linear model was used to explore whether injury claims and insurance payouts due to extreme heat decreased. A total of 9851 injury claims were included in the analysis. After policy implementation, the risk of occupational injuries and insurance payouts decreased by 13% (RR = 0.87, 95%CI: 0.75, 0.99) and 24% (RR = 0.76, 95% CI: 0.58, 0.94), respectively. The attributable fraction of extreme heat-related occupational injuries decreased from 3.17% (95%eCI: 1.35, 4.69) to 1.52% (95%eCI: -0.36, 3.15), which contributed to 0.86 million USD reduction of insurance payouts. Both males and females, low-educated, young and middle-aged workers, workers at small or medium-sized enterprises, engaging in manufacturing, and with both minor and severe injuries were apparently associated with decreased rates of extreme heat-related occupational injuries. The AMHP2012 policy contributed to the reduction of extreme heat-related occupational injuries and insurance payouts in Guangzhou, China, and this research provided novel evidence for decision-makers to better understand the necessity of implementing health protection policies among laborers under climate change.
Effect of Regular Precooling on Adaptation to Training in the Heat
Hui C Choo, Jeremiah J Peiffer, Joel W J Pang, Frankie H Y Tan, Abdul Rashid Aziz, Mohammed Ihsan, Jason K W Lee, Chris R Abbiss
Abstract
Purpose: This study investigated whether regular precooling would help to maintain day-to-day training intensity and improve 20-km cycling time trial (TT) performed in the heat. Twenty males cycled for 10 day × 60 min at perceived exertion equivalent to 15 in the heat (35 °C, 50% relative humidity), preceded by no cooling (CON, n = 10) or 30-min water immersion at 22 °C (PRECOOL, n = 10).
Methods: 19 participants (n = 9 and 10 for CON and PRECOOL, respectively) completed heat stress tests (25-min at 60% [Formula: see text] and 20-km TT) before and after heat acclimation.
Results: Changes in mean power output (∆MPO, P = 0.024) and heart rate (∆HR, P = 0.029) during heat acclimation were lower for CON (∆MPO – 2.6 ± 8.1%, ∆HR – 7 ± 7 bpm), compared with PRECOOL (∆MPO + 2.9 ± 6.6%, ∆HR – 1 ± 8 bpm). HR during constant-paced cycling was decreased from the pre-acclimation test in both groups (P 0.05). MPO (P = 0.016) and finish time (P = 0.013) for the 20-km TT were improved in PRECOOL but did not change in CON (P = 0.052 for MPO, P = 0.140 for finish time).
Conclusion: Precooling maintains day-to-day training intensity and does not appear to attenuate adaptation to training in the heat.
Wireless Battery-Free Body Sensor Networks Using Near-Field-Enabled Clothing
Nature Communications. 2020 Jan 23;11(1):444. doi: 10.1038/s41467-020-14311-2.
Rongzhou Lin, Han-Joon Kim, Sippanat Achavananthadith, Selman A Kurt, Shawn C C Tan, Haicheng Yao, Benjamin C K Tee, Jason K W Lee, John S Ho
Abstract
Networks of sensors placed on the skin can provide continuous measurement of human physiological signals for applications in clinical diagnostics, athletics and human-machine interfaces. Wireless and battery-free sensors are particularly desirable for reliable long-term monitoring, but current approaches for achieving this mode of operation rely on near-field technologies that require close proximity (at most a few centimetres) between each sensor and a wireless readout device. Here, we report near-field-enabled clothing capable of establishing wireless power and data connectivity between multiple distant points around the body to create a network of battery-free sensors interconnected by proximity to functional textile patterns. Using computer-controlled embroidery of conductive threads, we integrate clothing with near-field-responsive patterns that are completely fabric-based and free of fragile silicon components. We demonstrate the utility of the networked system for real-time, multi-node measurement of spinal posture as well as continuous sensing of temperature and gait during exercise.
Inhibition of Histone Deacetylase Reinstates Hippocampus-Dependent Long-Term Synaptic Plasticity and Associative Memory in Sleep-Deprived Mice
Cereb Cortex. 2020 Jun 1;30(7):4169-4182. doi: 10.1093/cercor/bhaa041.
Lik-Wei Wong, Yee Song Chong, Win Lee Edwin Wong, Sreedharan Sajikumar
Abstract
Sleep plays an important role in the establishment of long-term memory; as such, lack of sleep severely impacts domains of our health including cognitive function. Epigenetic mechanisms regulate gene transcription and protein synthesis, playing a critical role in the modulation of long-term synaptic plasticity and memory. Recent evidences indicate that transcriptional dysregulation as a result of sleep deprivation (SD) may contribute to deficits in plasticity and memory function. The histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA), also known as Vorinostat, a clinically approved drug for human use, has been shown to ameliorate cognitive deficits in several neurological disease models. To further explore the therapeutic effect of SAHA, we have examined its potential role in improving the SD-mediated impairments in long-term plasticity, associative plasticity, and associative memory. Here we show that SAHA preserves long-term plasticity, associative plasticity, and associative memory in SD hippocampus. Furthermore, we find that SAHA prevents SD-mediated epigenetic changes by upregulating histone acetylation, hence preserving the ERK-cAMP-responsive element-binding protein (CREB)/CREB-binding protein-brain-derived neurotrophic factor pathway in the hippocampus. These data demonstrate that modifying epigenetic mechanisms via SAHA can prevent or reverse impairments in long-term plasticity and memory that result from sleep loss. Thus, SAHA could be a potential therapeutic agent in improving SD-related memory deficits.
Organoid Cultures of MELAS Neural Cells Reveal Hyperactive Notch Signaling That Impacts Neurodevelopment
Cell Death Disease. 2020 Mar 13;11(3):182. doi: 10.1038/s41419-020-2383-6.
Winanto, Zi Jian Khong, Boon-Seng Soh, Yong Fan, Shi-Yan Ng
Abstract
Mutations in mitochondrial DNA (mtDNA), typically maternally inherited, can result in severe neurological conditions. There is currently no cure for mitochondrial DNA diseases and treatments focus on management of the symptoms rather than correcting the defects downstream of the mtDNA mutation. Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is one such mitochondrial disease that affects many bodily systems, particularly the central nervous system and skeletal muscles. Given the motor deficits seen in MELAS patients, we investigate the contribution of motor neuron pathology to MELAS. Using a spinal cord organoid system derived from induced pluripotent stem cells of a MELAS patient, as well as its isogenically corrected control, we found that high levels of Notch signaling underlie neurogenesis delays and neurite outgrowth defects that are associated with MELAS neural cultures. Furthermore, we demonstrate that the gamma-secretase inhibitor DAPT can reverse these neurodevelopmental defects.
Age-related Bone Loss Is Associated With FGF21 but Not IGFBP1 in Healthy Adults
Experimental Physiology. 2020 Apr;105(4):622-631. doi: 10.1113/EP088351. Epub 2020 Feb 17.
Shuen Yee Lee, Kai Deng Fam, Kar Ling Chia, Margaret M C Yap, Jorming Goh, Kwee Poo Yeo, Eric P H Yap, Sanjay H Chotirmall, Chin Leong Lim
Abstract
What is the central question of this study? Fibroblast growth factor 21 (FGF21) plays important therapeutic roles in metabolic diseases but is associated with bone loss, through insulin-like growth factor binding protein 1 (IGFBP1), in animals. However, the effect of the FGF21-IGFBP1 axis on age-related bone loss has not been explored in humans. What is the main finding and its importance? Using ‘genetically linked’ parent and child family pairs, we show that the FGF21 concentration, but not the IGFBP1 concentration, is higher in older than in younger adults. Our results suggest that age-associated decline in bone mineral density is associated with FGF21 and increased bone turnover but not likely to involve IGFBP1 in healthy humans. ABSTRACT: Bone fragility increases with age. The fibroblast growth factor 21 (FGF21)-insulin-like growth factor binding protein 1 (IGFBP1) axis regulates bone loss in animals. However, the role of FGF21 in mediating age-associated bone fragility in humans remains unknown. The purpose of this study was to explore the FGF21-regulatory axis in bone turnover and the age-related decline in bone mineral density (BMD). Twenty ‘genetically linked’ family (parent and child) pairs were recruited. Younger adults were 22-39 years old and older adults 60-71 years old. The BMD and serum concentrations of FGF21, IGFBP1, receptor activator of nuclear factor-κB ligand (RANKL), tartrate-resistant acid phosphatase 5b (TRAP5b) and bone-specific alkaline phosphatase (BAP) were measured. Older adults had 10-18% lower BMD at the hip and spine (P < 0.008) and a twofold higher FGF21 concentration (P 0.05). In humans, FGF21 might be involved in the age-associated decline in BMD, especially at the spine, through increased bone turnover. IGFBP1 is unlikely to be the downstream effector of FGF21 in driving the age-associated decline in BMD and in RANKL-associated osteoclast differentiation.
Concurrent high-intensity aerobic and resistance exercise modulates systemic release of alarmins (HMGB1, S100A8/A9, HSP70) and inflammatory biomarkers in healthy young men: a pilot study
Translational Medicine Communications volume 5, Article number: 4 (2020)
Jorming Goh, Peter Hofmann, Ning Hong Aw, Poh Ling Tan, Gerhard Tschakert, Alexander Mueller, Siew Cheng Wong, Frankie Tan & Linda Seo Hwee Gan
Abstract
Background
Intense exercise is a systemic stressor associated with the release of “danger” molecules – alarmins, by damaged or dying cells into systemic circulation to evoke a sterile inflammatory response. Compared with research in clinical diseases, physiological responses of alarmins to exercise and training are not well studied. Short-term responses to exercise and training using a panel of alarmins – HMGB1, S100A8/A9, HSP70 and sRAGE may reveal unique aspects of stress responses to strenuous exercise, with important ramifications when prescribing exercise to generally healthy adults.
Methods
A 3-week, high-intensity training program was performed by healthy young men (N = 7). Concurrent aerobic and resistance exercises were performed on 3 consecutive days each week. Blood and saliva were collected before (Pre), immediately after (Post), and 30 min (30 min) after exercise each week, and 24 h after the final exercise session in week 3 (24 h).
Results
Plasma HMGB1, S100A8/A9 and HSP70 increased from Pre to Post (P < 0.05), although at different timepoints during the study, and displayed different kinetics from IL-10, IL-8 and IFN-γ, suggesting unique mechanisms involved in modulating their release and clearance. CD14+CD16− monocytes increased from Pre to Post across 3 weeks; CD14+CD16+ monocytes increased from Pre to Post in week 2 and 3 (P < 0.05). ΔHMGB1 and ΔHSP70 correlated positively with ΔMCP-1 during 3 weeks of training. As well, ΔHMGB1 correlated positively with CD14+CD16− monocytes, suggesting higher alarmin release after strenuous exercise may involve increase in circulating monocytes.
Conclusions
Perturbations in systemic alarmins are novel biological signatures for assessing the inflammatory milieu of healthy adults during high-intensity exercise.
Influenza A Virus-Induced Apoptosis and Virus Propagation
Apoptosis. 2020 Feb;25(1-2):1-11.
doi: 10.1007/s10495-019-01575-3.
Patrick B Ampomah, Lina H K Lim
Abstract
Influenza A viruses (IAVs) are respiratory pathogens that cause severe morbidity and mortality worldwide. They affect cellular processes such as proliferation, protein synthesis, autophagy, and apoptosis. Although apoptosis is considered an innate cellular response to invading infectious pathogens, IAVs have evolved to encode viral proteins that modulate host cellular apoptosis in ways that support efficient viral replication and propagation. An understanding of the modulation of host responses is essential to the development of novel therapeutics for the treatment of IAV infections. In this review, we discuss the IAV lifecycle, biology, and strategies employed by the virus to modulate apoptosis to enhance viral survival and establish an infection.
Magnetic fields modulate metabolism and gut microbiome in correlation with Pgc‐1α expression: Follow‐up to an in vitro magnetic mitohormetic study
FASEB Journal. doi: 10.1096/fj.201903005RR.
Yee Kit Tai, Charmaine Ng, Kristy Purnamawati, Jasmine Lye Yee Yap, Jocelyn Naixin Yin, Craig Wong, Bharati Kadamb Patel, Poh Loong Soong, Pawel Pelczar, Jürg Fröhlich, Christian Beyer, Charlene Hui Hua Fong, Sharanya Ramanan, Marco Casarosa, Carmine Pasquale Cerrato, Zi Ling Foo, Rina Malathi Pannir Selvan, Elina Grishina, Ufuk Degirmenci, Shi Jie Toh, Pete J. Richards, Ali Mirsaidi, Karin Wuertz‐Kozak, Suet Yen Chong, Stephen J. Ferguson, Adriano Aguzzi, Monica Monici, Lei Sun, Chester L. Drum, Jiong‐Wei Wang, Alfredo Franco‐Obregón
Abstract
Exercise modulates metabolism and the gut microbiome. Brief exposure to low mT‐range pulsing electromagnetic fields (PEMFs) was previously shown to accentuate in vitro myogenesis and mitochondriogenesis by activating a calcium‐mitochondrial axis upstream of PGC‐1α transcriptional upregulation, recapitulating a genetic response implicated in exercise‐induced metabolic adaptations. We compared the effects of analogous PEMF exposure (1.5 mT, 10 min/week), with and without exercise, on systemic metabolism and gut microbiome in four groups of mice: (a) no intervention; (b) PEMF treatment; (c) exercise; (d) exercise and PEMF treatment. The combination of PEMFs and exercise for 6 weeks enhanced running performance and upregulated muscular and adipose Pgc‐1α transcript levels, whereas exercise alone was incapable of elevating Pgc‐1α levels. The gut microbiome Firmicutes /Bacteroidetes ratio decreased with exercise and PEMF exposure, alone or in combination, which has been associated in published studies with an increase in lean body mass. After 2 months, brief PEMF treatment alone increased Pgc‐1α and mitohormetic gene expression and after >4 months PEMF treatment alone enhanced oxidative muscle expression, fatty acid oxidation, and reduced insulin levels. Hence, short‐term PEMF treatment was sufficient to instigate PGC‐1α‐associated transcriptional cascades governing systemic mitohormetic adaptations, whereas longer‐term PEMF treatment was capable of inducing related metabolic adaptations independently of exercise.
Group III metabotropic glutamate receptors gate long-term potentiation and synaptic tagging/capture in rat hippocampal area CA2
eLife. doi: 10.7554/eLife.55344 .
Ananya Dasgupta, Yu Jia Lim, Krishna Kumar, Nimmi Baby, Ka Lam Karen Pang, Amrita Benoy, Thomas Behnisch, Sreedharan Sajikumar.
Abstract
Metabotropic glutamate receptors (mGluRs) play an important role in synaptic plasticity and memory and are largely classified based on amino acid sequence homology and pharmacological properties. Among group III metabotropic glutamate receptors, mGluR7 and mGluR4 show high relative expression in the rat hippocampal area CA2. Group III metabotropic glutamate receptors are known to down-regulate cAMP-dependent signaling pathways via the activation of Gi/o proteins. Here, we provide evidence that inhibition of group III mGluRs by specific antagonists permits an NMDA receptor- and protein synthesis-dependent long-lasting synaptic potentiation in the apparently long-term potentiation (LTP)-resistant Schaffer collateral (SC)-CA2 synapses. Moreover, long-lasting potentiation of these synapses transforms a transient synaptic potentiation of the entorhinal cortical (EC)-CA2 synapses into a stable long-lasting LTP, in accordance with the synaptic tagging/capture hypothesis (STC). Furthermore, this study also sheds light on the role of ERK/MAPK protein signaling and the downregulation of STEP protein in the group III mGluR inhibition-mediated plasticity in the hippocampal CA2 region, identifying them as critical molecular players. Thus, the regulation of group III mGluRs provides a conducive environment for the SC-CA2 synapses to respond to events that could lead to activity-dependent synaptic plasticity.
IL-13-driven alterations in hepatic cholesterol handling contributes to hypercholesterolemia in a rat model of minimal change disease
Clin Sci (Lond). 2020 Jan 31;134(2):225-237. doi: 10.1042/CS20190961.
Low LD, Lu L, Chan CY, Chen J, Yang HH, Yu H, Lee CGL, Ng KH, Yap HK.
Abstract
Circulating factors have been implicated in the pathogenesis of minimal change disease (MCD), and may have direct effects on cholesterol metabolism. This study investigated the pathogenesis of hypercholesterolemia in an IL-13 overexpression rat model of MCD prior to the onset of proteinuria, so as to establish the direct contribution of IL-13, especially with regard to hepatic cholesterol handling. In this model of MCD, the temporal relationship between hypercholesterolemia and proteinuria was first identified. Plasma proprotein convertase subtilisin/kexin type 9 (Pcsk9) and liver ATP-binding cassette sub-family G member 5 (Abcg5) were measured using ELISA. Liver Ldlr and liver X receptor alpha (Lxra) were quantified with Western blot. Abcg5-mediated cholesterol efflux in IL-13-stimulated rat primary hepatocytes was measured using taurocholate as cholesterol acceptor. The role of Lxra was validated using a luciferase assay in Lxre-luciferase-transfected IL-13-stimulated hepatocytes. IL-13-transfected rats developed hypercholesterolemia prior to proteinuria, with 35% of rats hypercholesterolemic but only 11% proteinuric by Day 20 (P = 0.04). These pre-proteinuric hypercholesterolemic rats showed elevations in total and LDL-cholesterol, but not hypertriglyceridemia or hepatic steatosis. The hypercholesterolemia was associated with increased hepatic Pcsk9 synthesis and enhanced circulating Pcsk9 levels, which correlated strongly with plasma total cholesterol (r = 0.73, P<0.001). The hypercholesterolemia was also contributed by decreased Abcg5 expression and activity, due to reduced Lxra expression. Lxra expression correlated with plasma total cholesterol levels (r = -0.52, P = 0.01), and overexpression of pLxra in rat hepatocytes abrogated the IL-13-mediated down-regulation of Lxre-driven gene expression. In conclusion, we have shown that IL-13 induced changes in hepatic cholesterol handling in a cytokine-induced rat model of MCD, resulting in hypercholesterolemia which can precede the onset of proteinuria.
Destroy, what destroys you
Oncoimmunology. 2019 Nov 3;9(1):1685301. doi: 10.1080/2162402X.2019.1685301. eCollection 2020.
Luu K, Nickles E, Schwarz H
Abstract
New evidence indicates the importance of CD137 for controlling Epstein-Barr virus (EBV) infections. (1) Mutations in CD137 predispose to EBV-associated diseases. (2) EBV induces ectopic CD137 expression, thereby activating a negative feed-back regulation and reducing T cell costimulation. These findings suggest CD137 agonists as new treatments for EBV-associated diseases.
CD137 ligand interacts with CD32a to trigger reverse CD137 ligand signaling
Zeng Q, Soe YM, Lim Y, Sobota RM, Schwarz H
Cell Mol Immunol. 2020 Feb 19. doi: 10.1038/s41423-020-0370-6
Zeng Q, Soe YM, Lim Y, Sobota RM, Schwarz H
Abstract
abstract no available
The relevance of soluble CD137 in the regulation of immune responses and for immunotherapeutic intervention
J Leukoc Biol. 2020 Feb 13. doi: 10.1002/JLB.2MR1119-224R
Luu K, Shao Z, Schwarz H
Abstract
CD137 is a potent costimulatory receptor. Several agonistic anti-CD137 antibodies are currently in clinical trials for tumor immunotherapy. Soluble forms of CD137 (sCD137) are generated by differential splicing and antagonize the activities of membrane-bound CD137 (mCD137) and of therapeutic CD137 agonists. sCD137 is found in sera of patients suffering from autoimmune diseases where it is a natural regulator of immune responses, and which has therapeutic potential for immune-mediated diseases. This review summarizes the current knowledge on sCD137, highlights its potential role in immunotherapy against cancer and in autoimmune diseases, and presents important issues to be addressed by future research.
Adaptor Protein Regulation in Immune Signalling
Frontiers in Immunology. 2020 Mar 13. doi: 10.3389/fimmu.2020.00441
erma NK, Tran T and Kelleher D
Abstract
Adaptor proteins are essential cellular components that govern signaling cross-talks in time and space with precise specificity. They contain multiple protein-binding modules that bring cellular enzymes and effector molecules into close proximity to their targets, controlling their activities. These proteins add another layer to the specificity of signaling by the type of protein-binding modules they engage in and their subcellular localization. Several adaptor proteins have been identified that coordinate signal transduction cascades in immune cells for their effector functions, including motility, activation, proliferation, and differentiation.
This Research Topic is a collection of work that aims to provide an overview of emerging roles of adaptor proteins in immune functions. We invited several immunologists and scientists to update the knowledge about adaptor proteins in immune signaling. A total of six original research papers and three insightful reviews in this collection provide meaningful insights toward the roles of adaptor proteins in the functioning of various immune cell types, including T cells, B cells, natural killer (NK) cells, mast cells, and monocytes.
The topic starts with a primary article by Böning et al. in which authors demonstrate a crucial role of the adhesion and degranulation-promoting adapter protein (ADAP) in NK cell priming, cytokine production, and cytotoxicity in an in vivo setting. Using an intracellular pathogen Listeria monocytogenes, they show that infection-primed NK cells lacking ADAP produce inefficient amounts of perforin and have impaired cytotoxic capacity. In another original article, Rudolph et al. demonstrate that T cell-specific conditional ADAP knockout mice display less severe experimental autoimmune encephalomyelitis (EAE). They propose that ADAP-expressing NK cells and myeloid cells might synergistically contribute to the observed mild EAE. These datasets expand the knowledge about roles of the cytosolic adapter protein ADAP in immune cell functions.
The review by Verma et al. summarizes the role of CG-NAP/kinase interactions in T cell homeostasis and functions. Due to its ability to dynamically and spatial-temporally interact with multiple kinases, CG-NAP appears central to the functional regulation of T cell activation, proliferation, differentiation, and migration. They suggest exploiting CG-NAP/kinase interactions as tunable therapeutic targets for T cell-mediated diseases.
In the next very informative review, Yablonski describes the biological and functional roles of the Grb2-related adaptor downstream of Shc (Gads) in regulating allergy and T cell-mediated immunity. She expounds that linker for activation of T cells (LAT), Gads, and Src homology 2 (SH2) domain-containing leukocyte phosphoprotein of 76 kDa (SLP-76) form heterotrimeric microclusters that mediate signal transduction via the T cell receptor (TCR) and the mast cell high-affinity IgE receptor FcεRI. The review sheds light on additional Gads-binding molecules, including co-stimulatory proteins CD28 and CD6, adaptor protein Shc, deubiquitinating enzymes USP8 and AMSH, the serine/threonine hematopoietic progenitor kinase 1 (HPK1) and the tyrosine kinase BCR-ABL.
Natural killer T (NKT) cells are a distinct subset of T cells sharing phenotypic and functional characteristics common to both conventional T cells and NK cells. They can recognize lipid antigens presented by the major histocompatibility complex (MHC) class I-like CD1d molecules (1). The review by Gerth and Mattner drives the reader into the intracellular processes mediated by adaptor proteins, in particular the adaptor protein SLP-76, in the unique biology of NKT cells, such as selection, differentiation, and activation.
The toll-like receptor (TLR) eight is a known endosomal sensor of degraded RNA in human phagocytes and is involved in the recognition of viruses, bacteria, and mitochondria (2, 3). Using a TLR8 antagonist in their original article, Moen et al. demonstrate an important role of TLR8 in human monocytes challenged with Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumonia, Pseudomonas aeruginosa, and Escherichia coli. They propose a novel signaling model where TLRs rapidly recruit and modify the interleukin-1 receptor-associated kinase 1 (IRAK-1) pool in monocytes, which may also sequester the adaptor protein MyD88 and/or IRAK-4, attenuating the interferon regulatory factor 5 (IRF5)-dependent cytokine induction and TLR8/IRF5 signaling.
The next original article by Zhou et al. demonstrates a vital role of the mitochondrial serine/threonine kinase phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) in innate antiviral immunity. The authors highlight that PINK1 positively regulates the retinoic acid-inducible gene I (RIG-I) triggered antiviral immunity by preventing the degradation of TNF receptor-associated factor 3 (TRAF3) and reducing the inhibition of the cellular responses mediated via the yes-associated protein (YAP).
Studies indicate that large antigen-containing particles, such as vaccinia virus, bacteria, and multicellular parasites, induce T cell-dependent B cell high-affinity antibody responses (4). Such responses require the internalization of large particulate antigens after the recognition by the B cell receptor (BCR). Using high-throughput quantitative image analysis and a panel of small molecule inhibitors, Verstegen et al. show that human B cells require IgM-BCR signaling via PI3K to efficiently engulf large anti-IgM-coated particles. This signaling cascade involves the cytoplasmic adaptor protein NCK in addition to the co-receptor CD19. They further demonstrate that the IgM-BCR/NCK signaling facilitates the activation of Rho family GTP-binding protein RAC1 to promote actin cytoskeleton remodeling necessary for particle internalization. They propose the NCK/PI3K/RAC1 signaling axis as an attractive target for biological intervention to prevent undesired antibody response to large particulate antigens.
The Skp1/Cul1/F-box ubiquitin ligase, β transducin repeat-containing protein (β-TrCP), regulates a diverse range of intracellular signaling pathways (5, 6). In this collection, Liu et al. demonstrate how β-TrCP restricts signal transduction via the TNF receptor-associated factor 6/IκB kinase (TRAF6/IKK) upstream of IκBα signaling induced by bacterial lipopolysaccharide, which is implicated in the regulation of inflammatory signaling by TLRs.
In conclusion, the collection of original articles and reviews provide new and valuable insight about the complex roles of adaptor proteins in immune regulation and also illustrate the important roles that these molecules play in immune function. We hope that this collection would inspire future research employing advance molecular and genetic tools to further dissect the interplay between adaptor proteins and their interacting partners in immune cells. In the near future, we anticipate much progress in this area of research, a greater appreciation of adaptor protein regulation of immune cells and the emergence of adaptor proteins as potential new targets for therapy.
CD151 in Respiratory Diseases
Front Cell Dev Biol. 2020 Feb 7;8:64. doi: 10.3389/fcell.2020.00064. eCollection 2020.
Wong AH, Tran T
Abstract
The tetraspanin, Cluster of Differentiation 151 (CD151), is ubiquitously expressed in adult tissue, especially in the lungs where it has been implicated in lung cancer, asthma, influenza, and idiopathic pulmonary fibrosis (IPF). CD151 interacts with laminin-binding integrins and growth factor receptors, and is reported in cancer-promoting processes such as tumor initiation, metastasis, and angiogenesis. In asthma, CD151 was shown to promote airways hyperresponsiveness through calcium signaling whereas in influenza, CD151 was shown to be a novel host factor for nuclear viral export signaling. Furthermore, CD151 was shown to be associated with increased disease severity and poorer survival outcome in asthma and lung cancer, respectively. In this review, we provide an update on the current understanding of CD151 with regards to its contribution to lung pathophysiology. We also summarize factors that have been shown to regulate CD151 expression and identify key areas that need to be taken into consideration for its utility as a screening or prognostic tool in disease management and/or as a therapeutic target for the treatment of lung diseases.
CD137 negatively affects “browning” of white adipose tissue during cold exposure
Journal of Biological Chemistry. 2020 Feb 14;295, 2034-2042. doi: 10.1074/jbc.AC119.011795.
Srivastava RK, Moliner A, Lee E-S, Nickles E, Sim E, Liu C, Schwarz H and Ibáñez CF
Abstract
Prolonged cold exposure stimulates the formation of brownlike adipocytes expressing UCP1 (uncoupling-protein-1) in subcutaneous white adipose tissue which, together with classical brown adipose tissue, contributes to maintaining body temperature in mammals through nonshivering thermogenesis. The mechanisms that regulate the formation of these cells, alternatively called beige or brite adipocytes, are incompletely understood. Here we report that mice lacking CD137, a cell surface protein used in several studies as a marker for beige adipocytes, showed elevated levels of thermogenic markers, including UCP1, increased numbers of beige adipocyte precursors, and expanded UCP1-expressing cell clusters in inguinal white adipose tissue after chronic cold exposure. CD137 knockout mice also showed enhanced cold resistance. These results indicate that CD137 functions as a negative regulator of “browning” in white adipose tissue and call into question the use of this protein as a functional marker for beige adipocytes.
Targeting autophagy using natural compounds for cancer prevention and therapy
Cancer. 2019 Apr 15;125(8):1228-1246. doi: 10.1002/cncr.31978.
Deng S, Shanmugam MK, Kumar AP, Yap CT, Sethi G, Bishayee A.
Abstract
Autophagy, also known as macroautophagy, is a tightly regulated process involved in the stress responses, such as starvation. It is a vacuolar, lysosomal pathway for the degradation of damaged proteins and organelles in eukaryotic cells. Autophagy also plays a key role in various tissue processes and immune responses and in the regulation of inflammation. Over the past decade, three levels of autophagy regulation have been identified in mammalian cells: 1) signaling, 2) autophagosome formation, and 3) autophagosome maturation and lysosomal degradation. Any deregulation of the autophagy processes can lead to the development of diverse chronic diseases, such as diabetes, obesity, cardiovascular disease, neurodegenerative disease, and malignancies. However, the potential role of autophagy in cancer is rather complex and has been associated with both the induction and the inhibition of neoplasia. Several synthetic autophagy modulators have been identified as promising candidates for cancer therapy. In addition, diverse phytochemicals derived from natural sources, such as curcumin, ursolic acid, resveratrol, thymoquinone, and γ-tocotrienol, also have attracted attention as promising autophagy modulators with minimal side effects. In this review, the authors discuss the importance of autophagy regulators and various natural compounds that induce and/or inhibit autophagy in the prevention and therapy of cancer.
Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems
Biomolecules. 2019 Sep 25;9(10). pii: E530. doi: 10.3390/biom9100530.
Tavakol S, Ashrafizadeh M, Deng S, Azarian M, Abdoli A, Motavaf M, Poormoghadam D, Khanbabaei H, Afshar EG, Mandegary A, Pardakhty A, Yap CT, Mohammadinejad R, Kumar AP.
Abstract
Autophagy modulation is considered to be a promising programmed cell death mechanism to prevent and cure a great number of disorders and diseases. The crucial step in designing an effective therapeutic approach is to understand the correct and accurate causes of diseases and to understand whether autophagy plays a cytoprotective or cytotoxic/cytostatic role in the progression and prevention of disease. This knowledge will help scientists find approaches to manipulate tumor and pathologic cells in order to enhance cellular sensitivity to therapeutics and treat them. Although some conventional therapeutics suffer from poor solubility, bioavailability and controlled release mechanisms, it appears that novel nanoplatforms overcome these obstacles and have led to the design of a theranostic-controlled drug release system with high solubility and active targeting and stimuli-responsive potentials. In this review, we discuss autophagy modulators-related signaling pathways and some of the drug delivery strategies that have been applied to the field of therapeutic application of autophagy modulators. Moreover, we describe how therapeutics will target various steps of the autophagic machinery. Furthermore, nano drug delivery platforms for autophagy targeting and co-delivery of autophagy modulators with chemotherapeutics/siRNA, are also discussed.
Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective
Cancers (Basel). 2020 Jan 18;12(1). pii: E238. doi: 10.3390/cancers12010238.
Ong MS, Deng S, Halim CE, Cai W, Tan TZ, Huang RY, Sethi G, Hooi SC, Kumar AP, Yap CT.
Abstract
Cytoskeletal proteins, which consist of different sub-families of proteins including microtubules, actin and intermediate filaments, are essential for survival and cellular processes in both normal as well as cancer cells. However, in cancer cells, these mechanisms can be altered to promote tumour development and progression, whereby the functions of cytoskeletal proteins are co-opted to facilitate increased migrative and invasive capabilities, proliferation, as well as resistance to cellular and environmental stresses. Herein, we discuss the cytoskeletal responses to important intracellular stresses (such as mitochondrial, endoplasmic reticulum and oxidative stresses), and delineate the consequences of these responses, including effects on oncogenic signalling. In addition, we elaborate how the cytoskeleton and its associated molecules present themselves as therapeutic targets. The potential and limitations of targeting new classes of cytoskeletal proteins are also explored, in the context of developing novel strategies that impact cancer progression.
Maternal factor NELFA drives a 2C-like state in mouse embryonic stem cells
Nature Cell Biology. 2020 Feb;22(2):175-186. doi: 10.1038/s41556-019-0453-8. Epub 2020 Jan 13.
Hu Z, Tan DEK, Chia G, Tan H, Leong HF, Chen BJ, Lau MS, Tan KYS, Bi X, Yang D, Ho YS, Wu B, Bao S, Wong ESM, Tee WW.
Abstract
Mouse embryonic stem cells (ESCs) sporadically transit into an early embryonic-like state characterized by the expression of 2-cell (2C) stage-restricted transcripts. Here, we identify a maternal factor-negative elongation factor A (NELFA)-whose heterogeneous expression in mouse ESCs is coupled to 2C gene upregulation and expanded developmental potential in vivo. We show that NELFA partners with Top2a in an interaction specific to the 2C-like state, and that it drives the expression of Dux-a key 2C regulator. Accordingly, loss of NELFA and/or Top2a suppressed Dux activation. Further characterization of 2C-like cells uncovered reduced glycolytic activity; remarkably, mere chemical suppression of glycolysis was sufficient to promote a 2C-like fate, obviating the need for genetic manipulation. Global chromatin state analysis on NELFA-induced cells revealed decommissioning of ESC-specific enhancers, suggesting ESC-state impediments to 2C reversion. Our study positions NELFA as one of the earliest drivers of the 2C-like state and illuminates factors and processes that govern this transition.
Inhibition of Histone Deacetylase Reinstates Hippocampus-Dependent Long-Term Synaptic Plasticity and Associative Memory in Sleep-Deprived Mice
Cerebral Cortex. 2020 Mar 16. bhaa041. doi: 10.1093/cercor/bhaa041
Wong L-W, Chong YS, Wong WLE, Sajikumar S
Abstract
Sleep plays an important role in the establishment of long-term memory; as such, lack of sleep severely impacts domains of our health including cognitive function. Epigenetic mechanisms regulate gene transcription and protein synthesis, playing a critical role in the modulation of long-term synaptic plasticity and memory. Recent evidences indicate that transcriptional dysregulation as a result of sleep deprivation (SD) may contribute to deficits in plasticity and memory function. The histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA), also known as Vorinostat, a clinically approved drug for human use, has been shown to ameliorate cognitive deficits in several neurological disease models. To further explore the therapeutic effect of SAHA, we have examined its potential role in improving the SD-mediated impairments in long-term plasticity, associative plasticity, and associative memory. Here we show that SAHA preserves long-term plasticity, associative plasticity, and associative memory in SD hippocampus. Furthermore, we find that SAHA prevents SD-mediated epigenetic changes by upregulating histone acetylation, hence preserving the ERK–cAMP-responsive element-binding protein (CREB)/CREB-binding protein–brain-derived neurotrophic factor pathway in the hippocampus. These data demonstrate that modifying epigenetic mechanisms via SAHA can prevent or reverse impairments in long-term plasticity and memory that result from sleep loss. Thus, SAHA could be a potential therapeutic agent in improving SD-related memory deficits.
Solar radiation and the validity of infrared tympanic temperature during exercise in the heat.
Int J Biometeorol. 2019 Nov 9. doi: 10.1007/s00484-019-01791-1. [Epub ahead of print]
Otani H, Kaya M, Tamaki A, Hosokawa Y, Lee JKW
Abstract
We investigated the validity of infrared tympanic temperature (IR-Tty) during exercise in the heat with variations in solar radiation. Eight healthy males completed stationary cycling trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30°C with 50% relative humidity. Three solar radiation conditions, 0, 250 and 500 W/m2, were tested using a ceiling-mounted solar simulator (metal-halide lamps) over a 3 × 2 m irradiated area. IR-Tty and rectal temperature (Tre) were similar before and during exercise in each trial (P > 0.05). Spearman’s rank correlation coefficient (rs) demonstrated very strong (250 W/m2, rs = 0.87) and strong (0 W/m2, rs = 0.73; 500 W/m2, rs = 0.78) correlations between IR-Tty and Tre in all trials (P < 0.001). A Bland-Altman plot showed that mean differences (SD; 95% limits of agreement; root mean square error) between IR-Tty and Tre were - 0.11°C (0.46; - 1.00 to 0.78°C; 0.43 ± 0.16°C) in 0 W/m2, - 0.13°C (0.32; - 0.77 to 0.50°C; 0.32 ± 0.10°C) in 250 W/m2 and - 0.03°C (0.60; - 1.21 to 1.14°C; 0.46 ± 0.27°C) in 500 W/m2. A positive correlation was found in 500 W/m2 (rs = 0.51; P < 0.001) but not in 250 W/m2 (rs = 0.04; P = 0.762) and 0 W/m2 (rs = 0.04; P = 0.732), indicating a greater elevation in IR-Tty than Tre in 500 W/m2. Percentage of target attainment within ± 0.3°C between IR-Tty and Tre was higher in 250 W/m2 (100 ± 0%) than 0 (93 ± 7%) and 500 (90 ± 10%; P < 0.05) W/m2. IR-Tty is acceptable for core temperature monitoring during exercise in the heat when solar radiation is ≤ 500 W/m2, and its accuracy increases when solar radiation is 250 W/m2 under our study conditions.
Workplace Heat: An increasing threat to occupational health and productivityntries during climate change.
American Journal Industrial Medicine, 62 (12): 1076-1078. doi: 10.1002/ajim.23051
Kjellstrom, T, Lemke, B, Lee, JKW.
Abstract
No abstract is available for this article.
The physiological strain index modified for trained heat acclimatized individuals in outdoor heat.
Byrne C, Lee JKW.
Abstract
Purpose: To determine if the Physiological Strain Index (PSI), in original or modified form, can evaluate heat strain on a 0-10 scale, in trained and heat-acclimatized men undertaking a competitive half-marathon run in outdoor heat. Methods: Core (intestinal) temperature (TC) and heart rate (HR) were recorded continuously in 24 men (mean [SD] age = 26 [3] y, VO2peak = 59 [5] mL·kg·min-1). A total of 4 versions of the PSI were computed: original PSI with upper constraints of TC 39.5°C and HR 180 beats·min-1 (PSI39.5/180) and 3 modified versions of PSI with each having an age-predicted maximal HR constraint and graded TC constraints of 40.0°C (PSI40.0/PHRmax), 40.5°C (PSI40.5/PHRmax), and 41.0°C (PSI41.0/PHRmax). Results: In a warm (26.1-27.3°C) and humid (79-82%) environment, all runners finished the race asymptomatic in 107 (10) (91-137) min. Peak TC and HR were 39.7°C (0.5°C) (38.5-40.7°C) and 186 (6) (175-196) beats·min-1, respectively. In total, 63% exceeded TC 39.5°C, 71% exceeded HR 180 beats·min-1, and 50% exceeded both of the original PSI upper TC and HR constraints. The computed heat strain was significantly greater with PSI39.5/180 than all other methods (P < .003). PSI >10 was observed in 63% of runners with PSI39.5/180, 25% for PSI40.0/PHRmax, 8% for PSI40.5/PHRmax, and 0% for PSI41.0/PHRmax. Conclusions: The PSI was able to quantify heat strain on a 0-10 scale in trained and heat-acclimatized men undertaking a half-marathon race in outdoor heat, but only when the upper TC and HR constraints were modified to 41.0°C and age-predicted maximal HR, respectively.
Activation of microglia in acute hippocampal slices affects activity-dependent long-term potentiation and synaptic tagging and capture in area CA1.
Neurobiol Learn Mem. 2019 Sep;163:107039. doi: 10.1016/j.nlm.2019.107039. Epub 2019 Jul 3.
Raghuraman R, Karthikeyan A, Wei WL, Dheen ST, Sajikumar S.
Abstract
Activity dependent setting of synaptic tags is critical for the establishment and maintenance of long-term plasticity and its associative properties such as synaptic tagging and capture (STC), a widely studied cellular model of associative memory. Although the known mechanisms of STC such as setting of synaptic tags or distribution of plasticity related proteins (PRPs) are the processes mainly happening within the neuronal compartments, the role of non-neuronal components is still elusive. Here, we report that microglia has a specific role in setting the synaptic tags and thus promotes long-term plasticity and STC. Treatment of hippocampal slices with clodronate, a specific inhibitor of microglia, resulted in an activated morphology of microglia but not of the hippocampal pyramidal neurons, oligodendrocytes or astrocytes. Activation of microglia before or 60 min after the induction of long-term plasticity prevented its maintenance and thus the expression of STC. Interestingly, activation of microglia 2 h after the induction of long-term plasticity neither prevented its maintenance nor its associative interaction with activated nearby synaptic populations. Given the half-life of synaptic tags is until about 60-90 min, activation of microglia beyond this time point while the maintenance phase is still unperturbed, suggests a lack of microglial interference in the synthesis or trigger of plasticity related products. Thus, our study provides the first evidence that microglia play a critical role in the setting of synaptic tags during the early phase of activity dependent plasticity.
MicroRNA-134-5p inhibition rescues long-term plasticity and synaptic tagging/capture in an Aβ(1-42)-induced model of Alzheimer’s disease.
Aging Cell. 2019 Oct 17:e13046. doi: 10.1111/acel.13046. [Epub ahead of print]
Baby N, Alagappan N, Dheen ST, Sajikumar S.
Abstract
Progressive memory loss is one of the most common characteristics of Alzheimer’s disease (AD), which has been shown to be caused by several factors including accumulation of amyloid β peptide (Aβ) plaques and neurofibrillary tangles. Synaptic plasticity and associative plasticity, the cellular basis of memory, are impaired in AD. Recent studies suggest a functional relevance of microRNAs (miRNAs) in regulating plasticity changes in AD, as their differential expressions were reported in many AD brain regions. However, the specific role of these miRNAs in AD has not been elucidated. We have reported earlier that late long-term potentiation (late LTP) and its associative mechanisms such as synaptic tagging and capture (STC) were impaired in Aβ (1-42)-induced AD condition. This study demonstrates that expression of miR-134-5p, a brain-specific miRNA is upregulated in Aβ (1-42)-treated AD hippocampus. Interestingly, the loss of function of miR-134-5p restored late LTP and STC in AD. In AD brains, inhibition of miR-134-5p elevated the expression of plasticity-related proteins (PRPs), cAMP-response-element binding protein (CREB-1) and brain-derived neurotrophic factor (BDNF), which are otherwise downregulated in AD condition. The results provide the first evidence that the miR-134-mediated post-transcriptional regulation of CREB-1 and BDNF is an important molecular mechanism underlying the plasticity deficit in AD; thus demonstrating the critical role of miR-134-5p as a potential therapeutic target for restoring plasticity in AD condition.
Epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway involved in long-term potentiation and synaptic plasticity in rats.
Glia. 2019 Nov 8. doi: 10.1002/glia.23748. [Epub ahead of print]
Saw G, Krishna K, Gupta N, Soong TW, Mallilankaraman K, Sajikumar S, Dheen ST.
Abstract
Microglia are the main form of immune defense in the central nervous system. Microglia express phosphatidylinositol 3-kinase (PI3K), which has been shown to play a significant role in synaptic plasticity in neurons and inflammation via microglia. This study shows that microglial PI3K is regulated epigenetically through histone modifications and posttranslationally through sumoylation and is involved in long-term potentiation (LTP) by modulating the expression of brain-derived neurotrophic factor (BDNF), which has been shown to be involved in neuronal synaptic plasticity. Sodium butyrate, a histone deacetylase inhibitor, upregulates PI3K expression, the phosphorylation of its downstream effectors, AKT and cAMP response element-binding protein (CREB), and the expression of BDNF in microglia, suggesting that BDNF secretion is regulated in microglia via epigenetic regulation of PI3K. Further, knockdown of SUMO1 in BV2 microglia results in a decrease in the expression of PI3K, the phosphorylation of AKT and CREB, as well as the expression of BDNF. These results suggest that microglial PI3K is epigenetically regulated by histone modifications and posttranslationally modified by sumoylation, leading to altered expression of BDNF. Whole-cell voltage-clamp showed the involvement of microglia in neuronal LTP, as selective ablation or disruption of microglia with clodronate in rat hippocampal slices abolished LTP. However, LTP was rescued when the same hippocampal slices were treated with active PI3K or BDNF, indicating that microglial PI3K/AKT signaling contributes to LTP and synaptic plasticity. Understanding the mechanisms by which microglial PI3K influences synapses provides insights into the ways it can modulate synaptic transmission and plasticity in learning and memory.
CD137L-DCs, Potent Immune-Stimulators-History, Characteristics, and Perspectives.
Front Immunol. 2019 Oct 2;10:2216. doi: 10.3389/fimmu.2019.02216. eCollection 2019.
Zeng Q, Zhou Y, Schwarz H.
Abstract
Dendritic cell (DC)-based immunotherapies are being explored for over 20 years and found to be very safe. Most often, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4)-induced monocyte-derived DCs (moDCs) are being used, which have demonstrated some life-prolonging benefit to patients of multiple tumors. However, the limited clinical response and efficacy call for the development of more potent DCs. CD137L-DC may meet this demand. CD137L-DCs are a novel type of monocyte-derived inflammatory DCs that are induced by CD137 ligand (CD137L) agonists. CD137L is expressed on the surface of antigen-presenting cells, including monocytes, and signaling of CD137L into monocytes induces their differentiation to CD137L-DCs. CD137L-DCs preferentially induce type 1 T helper (Th1) cell polarization and strong type 1 CD8+ T cell (Tc1) responses against tumor-associated viral antigens. The in vitro T cell-stimulatory capacity of CD137L-DCs is superior to that of conventional moDCs. The transcriptomic profile of CD137L-DC is highly similar to that of in vivo DCs at sites of inflammation. The strict activation dependence of CD137 expression and its restricted expression on activated T cells, NK cells, and vascular endothelial cells at inflammatory sites make CD137 an ideally suited signal for the induction of monocyte-derived inflammatory DCs in vivo. These findings and their potency encouraged a phase I clinical trial of CD137L-DCs against Epstein-Barr virus-associated nasopharyngeal carcinoma. In this review, we introduce and summarize the history, the characteristics, and the transcriptional profile of CD137L-DC, and discuss the potential development and applications of CD137L-DC.
Development of a Bispecific Antibody Targeting CD30 and CD137 on Hodgkin and Reed-Sternberg Cells.
Front Oncol. 2019 Sep 24;9:945. doi: 10.3389/fonc.2019.00945. eCollection 2019.
Rajendran S, Li Y, Ngoh E, Wong HY, Cheng MS,2, Wang CI, Schwarz H.
Abstract
Hodgkin Lymphoma (HL) is a malignancy that frequently affects young adults. Although, there are effective treatments not every patient responds, necessitating the development of novel therapeutic approaches, especially for relapsed and refractory cases. The two TNF receptor family members CD30 and CD137 are expressed on Hodgkin and Reed Sternberg (HRS) cells, the malignant cells in HL. We found that this co-expression is specific for HRS cells. Based on this discovery we developed a bispecific antibody that binds preferentially to the CD30, CD137-double positive HRS cells. The CD30, CD137 bispecific antibody gets internalized into HRS cells opening up the possibility to use it as a carrier for a toxin. This antibody also induces antibody-dependent, cell-mediated cytotoxicity in CD30, CD137-double positive HRS cells. The enhances specificity of the CD30, CD137 bispecific antibody to HRS cells makes it a promising candidate for development as a novel HL treatment.
Sarcopenia: Tilting the Balance of Protein Homeostasis.
Proteomics. 2019 Nov 13:e1800411. doi: 10.1002/pmic.201800411. [Epub ahead of print]
Tan KT, Ang SJ, Tsai SY.
Abstract
Sarcopenia, defined as age-associated decline of muscle mass and function, is a risk factor for mortality and disability, and comorbid with several chronic diseases such as type II diabetes and cardiovascular diseases. Clinical trials showed that nutritional supplements had positive effects on muscle mass, but not on muscle function and strength, demonstrating our limited understanding of the molecular events involved in the ageing muscle. Protein homeostasis, the equilibrium between protein synthesis and degradation, is proposed as the major mechanism underlying the development of sarcopenia. As the key central regulator of protein homeostasis, the mammalian target of rapamycin (mTOR) is proposed to be essential for muscle hypertrophy. Paradoxically, sustained activation of mTOR complex 1 (mTORC1) is associated with a loss of sensitivity to extracellular signaling in the elderly. It is not understood why sustained mTORC1 activity, which should induce muscle hypertrophy, instead results in muscle atrophy. Here, recent findings on the implications of disrupting protein homeostasis on muscle physiology and sarcopenia development in the context of mTOR/protein kinase B (AKT) signaling are reviewed. Understanding the role of these molecular mechanisms during the ageing process will contribute towards the development of targeted therapies that will improve protein metabolism and reduce sarcopenia.
Thermoregulation in the Aging Population and Practical Strategies to Overcome a Warmer Tomorrow.
Proteomics. 2019 Oct 25:e1800468. doi: 10.1002/pmic.201800468. [Epub ahead of print]
Tan CCS, Chin LKK, Low ICC.
Abstract
As global temperatures continue to rise, improving thermal tolerance in the aged population is crucial to counteract age-associated impairments in thermoregulatory function. Impairments in reflex cutaneous vasodilation and sweating response can augment the vulnerability of older adults to heat-related injuries following exposure to heat stress. Mechanisms underlying a compromised cutaneous vasodilation are suggested to include reduced sympathetic neural drive, diminished cholinergic co-transmitter contribution, and altered second messenger signaling events. On the other hand, impairments in sweating response are ascribed to reduced sweat gland cholinergic sensitivity and altered cyclooxygenase and nitric oxide signaling. Several practical mitigation strategies such as exercise, passive heating, and behavioral adaptations are proposed as means to overcome heat stress and improve thermal tolerance in the aged. Aerobic exercise training is shown to be amongst the most effective ways to enhance thermoregulatory function. However, in elderly with limited exercise capability due to chronic diseases and mobility issues, passive heating can serve as a functional alternative as it has been shown to confer similar benefits to that of exercise training. Supplementary to exercise training and passive heating, behavioral adaptations can be applied to further enhance the heat-preparedness of the aged.
Heart Rate Measures From Wrist-Worn Activity Trackers in a Laboratory and Free-Living Setting: Validation Study.
JMIR Mhealth Uhealth. 2019 Oct 2;7(10):e14120. doi: 10.2196/14120.
Müller AM, Wang NX, Yao J, Tan CS, Low ICC, Lim N, Tan J, Tan A, Müller-Riemenschneider F.
Abstract
BACKGROUND:
Wrist-worn activity trackers are popular, and an increasing number of these devices are equipped with heart rate (HR) measurement capabilities. However, the validity of HR data obtained from such trackers has not been thoroughly assessed outside the laboratory setting.
OBJECTIVE:
This study aimed to investigate the validity of HR measures of a high-cost consumer-based tracker (Polar A370) and a low-cost tracker (Tempo HR) in the laboratory and free-living settings.
METHODS:
Participants underwent a laboratory-based cycling protocol while wearing the two trackers and the chest-strapped Polar H10, which acted as criterion. Participants also wore the devices throughout the waking hours of the following day during which they were required to conduct at least one 10-min bout of moderate-to-vigorous physical activity (MVPA) to ensure variability in the HR signal. We extracted 10-second values from all devices and time-matched HR data from the trackers with those from the Polar H10. We calculated intraclass correlation coefficients (ICCs), mean absolute errors, and mean absolute percentage errors (MAPEs) between the criterion and the trackers. We constructed decile plots that compared HR data from Tempo HR and Polar A370 with criterion measures across intensity deciles. We investigated how many HR data points within the MVPA zone (≥64% of maximum HR) were detected by the trackers.
RESULTS:
Of the 57 people screened, 55 joined the study (mean age 30.5 [SD 9.8] years). Tempo HR showed moderate agreement and large errors (laboratory: ICC 0.51 and MAPE 13.00%; free-living: ICC 0.71 and MAPE 10.20%). Polar A370 showed moderate-to-strong agreement and small errors (laboratory: ICC 0.73 and MAPE 6.40%; free-living: ICC 0.83 and MAPE 7.10%). Decile plots indicated increasing differences between Tempo HR and the criterion as HRs increased. Such trend was less pronounced when considering the Polar A370 HR data. Tempo HR identified 62.13% (1872/3013) and 54.27% (5717/10,535) of all MVPA time points in the laboratory phase and free-living phase, respectively. Polar A370 detected 81.09% (2273/2803) and 83.55% (9323/11,158) of all MVPA time points in the laboratory phase and free-living phase, respectively.
CONCLUSIONS:
HR data from the examined wrist-worn trackers were reasonably accurate in both the settings, with the Polar A370 showing stronger agreement with the Polar H10 and smaller errors. Inaccuracies increased with increasing HRs; this was pronounced for Tempo HR.
Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.
Biomaterials. 2019 May;201:16-32. doi: 10.1016/j.biomaterials.2019.01.046.
Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.
Abstract
Interconnected macroporous hydrogel is hydrophilic; it exhibits soft tissue-like mechanical property and aqueous-stable macroporosity for 3D spheroid culture. There is an unmet need to develop cleavable macroporous hydrogel, for the ease of retrieving functional spheroids for further in vitro and in vivo applications. We have developed and comprehensively characterized a hydroxypropyl-cellulose-disulfide sponge by systematically identifying strategies and synthesis schemes to confer cleavability to the sponge under cell-friendly conditions. It preserved the essential advantages of the macroporous hydrogel to support 3D spheroid formation and maintenance of sensitive hepatocytes while allowing rapid cleavage and retrieval of functional spheroids. By culturing HepaRG as spheroids in the cleavable sponge, we have accelerated HepaRG differentiation to 9 days compared to 28 days in 2D culture. Cytochrome P450 basal activity reached significantly higher level, while albumin secretion and fluorescein diacetate staining indicated the same at day 5. The purity of albumin+ hepatocytes reached 92.9% versus 7.1% of CK19+ cholangiocytes at day 9, a much stronger preference for hepatocytes than the 60% albumin+ hepatocytes purity in 2D culture. HepaRG differentiated hepatocytes were retrieved by cleaving the sponge with 10 mM tris-(2-carboxyethyl)-phosphine (TCEP) within 30 min preserving viability, plateability and positive albumin staining of the hepatocyte spheroids. This cleavable macroporous hydrogel sponge will support the rapid development of various 3D spheroid- or organoid-based applications in basic research and drug testing.
Sequential drug delivery for liver diseases.
Adv Drug Deliv Rev. 2019 Sep – Oct;149-150:72-84. doi: 10.1016/j.addr.2019.11.001.
Huang X, Lee F, Teng Y, Lingam CB, Chen Z, Sun M, Song Z, Balachander GM, Leo HL, Guo Q, Shah I, Yu H.
Abstract
The liver performs critical physiological functions such as metabolism/detoxification and blood homeostasis/biliary excretion. A high degree of blood access means that a drug’s resident time in any cell is relatively short. This short drug exposure to cells requires local sequential delivery of multiple drugs for optimal efficacy, potency, and safety. The high metabolism and excretion of drugs also impose both technical challenges and opportunities to sequential drug delivery. This review provides an overview of the sequential events in liver regeneration and the related liver diseases. Using selected examples of liver cancer, hepatitis B viral infection, fatty liver diseases, and drug-induced liver injury, we highlight efforts made for the sequential delivery of small and macromolecular drugs through different biomaterials, cells, and microdevice-based delivery platforms that allow fast delivery kinetics and rapid drug switching. As this is a nascent area of development, we extrapolate and compare the results with other sequential drug delivery studies to suggest possible application in liver diseases, wherever appropriate.
Pathogenic Bhlhe40+ GM-CSF+ CD4+ T Cells Promote Indirect Alloantigen Presentation in the GI Tract during GVHD.
Blood. 2019 Dec 27. pii: blood.2019001696. doi: 10.1182/blood.2019001696. [Epub ahead of print]
Piper C, Zhou V, Komorowski R, Szabo A, Vincent B, Serody J, Alegre ML, Edelson BT, Taneja R, Drobyski WR.
Abstract
Gastrointestinal (GI) tract involvement is the major cause of morbidity and mortality in acute graft versus host disease (GVHD) and pathological damage is largely attributable to inflammatory cytokine production. Recently, GM-CSF has been identified as a cytokine that mediates inflammation in the GI tract, but the transcriptional program that governs GM-CSF production and the mechanism by which GM-CSF links adaptive to innate immunity within this tissue site have not been defined. In the current study, we identified Bhlhe40 as a key transcriptional regulator that governs GM-CSF production by CD4+ T cells and mediates pathological damage in the GI tract during GVHD. In addition, we observed that GM-CSF was not regulated by either IL-6 or IL-23 which are both potent inducers of GVHD-induced colonic pathology, indicating that GM-CSF constitutes a nonredundant inflammatory pathway in the GI tract. Mechanistically, GM-CSF had no adverse effect on regulatory T cell reconstitution, but linked adaptive to innate immunity by enhancing the activation of donor-derived dendritic cells in the colon and subsequent accumulation of these cells in the mesenteric lymph nodes. In addition, GM-CSF promoted indirect alloantigen presentation resulting in the accumulation of donor-derived T cells with a proinflammatory cytokine phenotype in the colon. Thus, Bhlhe40+ GM-CSF+ CD4+ T cells constitute a colitogenic T cell population that promotes indirect alloantigen presentation and pathological damage within the GI tract, positioning GM-CSF as a key regulator of GVHD in the colon and a potential therapeutic target for amelioration of this disease.
Interweaving Tumor Heterogeneity into the Cancer Epigenetic/Metabolic Axis.
Antioxid Redox Signal. 2019 Dec 16. doi: 10.1089/ars.2019.7942. [Epub ahead of print]
Leung JY, Chia K, Ong DST, Taneja R.
Abstract
Significance: The epigenomic/metabolic landscape in cancer has been studied extensively in the past decade and forms the basis of various drug targets. Yet, cancer treatment remains a challenge, with clinical trials exhibiting limited efficacy and high relapse rates. Patients respond differently to therapy, which is fundamentally attributed to tumor heterogeneity, both across and within tumors. This review focuses on the interactions between the heterogeneous tumor microenvironment (TME) and the epigenomic/metabolic axis in cancer, as well as the emerging technologies under development to aid heterogeneity studies. Recent Advances: Interlinks between epigenetics and metabolism in cancer have been reported. Emerging studies have unveiled interactions between the TME and cancer cells that play a critical role in regulating epigenetics and reprogramming cancer metabolism, suggesting a three-way cross talk. Critical Issues: This cross talk accentuates the multiplex nature of cancer, and the importance of considering tumor heterogeneity in various epigenomic/metabolic cancer studies. Future Directions: With the advancement in single-cell profiling, it may be possible to identify cancer subclones and their unique vulnerabilities to develop a multimodal therapy. Drugs targeting the TME are currently being studied, and a better understanding of the TME in regulating cancer epigenetics and metabolism may hold the key to identifying novel therapeutic targets.
Aurora kinase A-mediated phosphorylation of mPOU at a specific site drives skeletal muscle differentiation.
J Biochem. 2019 Oct 30. pii: mvz088. doi: 10.1093/jb/mvz088. [Epub ahead of print]
Karthigeyan D, Bose A, Boopathi R, Rao VJ, Shima H, Bharathy N, Igarashi K, Taneja R, Trivedi AK, Kundu TK.
Abstract
Aurora kinases are Ser/Thr-directed protein kinases which play pivotal roles in mitosis. Recent evidences highlight the importance of these kinases in multiple biological events including skeletal muscle differentiation. Our earlier study identified the transcription factor POU6F1 (or mPOU) as a novel Aurora kinase (Aurk) A substrate. Here, we report that AurkA phosphorylates mPOU at Ser197 and inhibit its DNA binding ability. Delving into mPOU physiology, we find that the phospho-mimic (S197D) mPOU mutant exhibits enhancement, while the wild type (WT) or the phospho-deficient mutant shows retardation in C2C12 myoblast differentiation. Interestingly, POU6F1 depletion phenocopies S197D-mPOU overexpression in the differentiation context. Collectively, our results signify mPOU as a negative regulator of skeletal muscle differentiation and strengthen the importance of AurkA in skeletal myogenesis.
Mitochondrial Dysfunction at the Center of Cancer Therapy
Antioxid Redox Signal. 2019 Nov 4. doi: 10.1089/ars.2019.7898. [Epub ahead of print]
Chiu HY, Tay EXY, Ong DST, Taneja R
Abstract
Significance: Mitochondria undergo constant morphological changes through fusion, fission, and mitophagy. As the key organelle in cells, mitochondria are responsible for numerous essential cellular functions such as metabolism, regulation of calcium (Ca2+), generation of reactive oxygen species, and initiation of apoptosis. Unsurprisingly, mitochondrial dysfunctions underlie many pathologies including cancer. Recent Advances: Currently, the gold standard for cancer treatment is chemotherapy, radiation, and surgery. However, the efficacy of these treatments varies across different cancer cells. It has been suggested that mitochondria may be at the center of these diverse responses. In the past decade, significant advances have been made in understanding distinct types of mitochondrial dysfunctions in cancer. Through investigations of underlying mechanisms, more effective treatment options are developed. Critical Issues: We summarize various mitochondria dysfunctions in cancer progression that have led to the development of therapeutic options. Current mitochondrial-targeted therapies and challenges are discussed. Future Directions: To address the “root” of cancer, utilization of mitochondrial-targeted therapy to target cancer stem cells may be valuable. Investigation of other areas such as mitochondrial trafficking may offer new insights into cancer therapy. Moreover, common antibiotics could be explored as mitocans, and synthetic lethality screens can be utilized to overcome the plasticity of cancer cells.
Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective
Cancers. 2020 Jan; 12(1): 238. doi: 10.3390/cancers12010238.
Ong MS, Deng S, Halim CE, Cai W, Tan TZ, Huang RY-J, Sethi G, Hooi SC,*, Kumar AP,* and Yap CT*
Abstract
Cytoskeletal proteins, which consist of different sub-families of proteins including microtubules, actin and intermediate filaments, are essential for survival and cellular processes in both normal as well as cancer cells. However, in cancer cells, these mechanisms can be altered to promote tumour development and progression, whereby the functions of cytoskeletal proteins are co-opted to facilitate increased migrative and invasive capabilities, proliferation, as well as resistance to cellular and environmental stresses. Herein, we discuss the cytoskeletal responses to important intracellular stresses (such as mitochondrial, endoplasmic reticulum and oxidative stresses), and delineate the consequences of these responses, including effects on oncogenic signalling. In addition, we elaborate how the cytoskeleton and its associated molecules present themselves as therapeutic targets. The potential and limitations of targeting new classes of cytoskeletal proteins are also explored, in the context of developing novel strategies that impact cancer progression.
Maternal factor NELFA drives a 2C-like state in mouse embryonic stem cells
Nature Cell Biology. 2020 Jan. doi: 10.1038/s41556-019-0453-8.
Hu Z, Tan DEK, Chia G, Tan H, Leong HF, Chen BJ, Lau MS, Tan KYS, Bi X, Yang D,
Ho YS, Wu B, Bao S, Wong ESM & Tee W-W
Abstract
Mouse embryonic stem cells (ESCs) sporadically transit into an early embryonic-like state characterized by the expression of 2-cell (2C) stage-restricted transcripts. Here, we identify a maternal factor—negative elongation factor A (NELFA)—whose heterogeneous expression in mouse ESCs is coupled to 2C gene upregulation and expanded developmental potential in vivo. We show that NELFA partners with Top2a in an interaction specific to the 2C-like state, and that it drives the expression of Dux—a key 2C regulator. Accordingly, loss of NELFA and/or Top2a suppressed Dux activation. Further characterization of 2C-like cells uncovered reduced glycolytic activity; remarkably, mere chemical suppression of glycolysis was sufficient to promote a 2C-like fate, obviating the need for genetic manipulation. Global chromatin state analysis on NELFA-induced cells revealed decommissioning of ESC-specific enhancers, suggesting ESC-state impediments to 2C reversion. Our study positions NELFA as one of the earliest drivers of the 2C-like state and illuminates factors and processes that govern this transition.
Role of formyl peptide receptor 2 (FPR2) in the normal brain and in neurological conditions
Neural Regeneration Research. 2019 Dec;14(12):2071-2072. doi: 10.4103/1673-5374.262575.
Ong WY, Chua JJE
Abstract
There is much recent interest in the role of the anti-inflammatory molecules and their receptors in the normal brain and in neurological disorders. The formyl peptide receptor (FPR) subfamily of G protein-coupled receptors play important roles in these processes. Binding to specific peptides triggers activation of FPRs, leading to signalling events that regulate inflammatory responses. One member of this subfamily of receptors is FPR2, also known as ALX (the lipoxin A4 (LXA4) receptor). FPR2 is specifically activated by LXA4 and resolvin D1 (RvD1) (Pirault and Bäck, 2018). LXA4 is an anti-inflammatory molecule produced by the action of lipoxygenases on arachidonic acid, while RvD1 is produced by the action of lipoxygenases on docosahexaenoic acid, a component of fish oil. Activation of FPR2 by LXA4 or RvD1 triggers downstream signalling cascades, e.g., inhibition of calcium-calmodulin dependent protein kinase and p38 mitogen-activated protein kinase phosphorylation, leading to a reduction in inflammatory responses. Annexin A1 (ANXA1) is another molecule which could interact with FPR2. A Ca 2+-dependent phospholipid-binding protein, ANXA1 suppresses phospholipase A2 activity to reduce arachidonic acid and eicosanoid production and decrease leukocyte inflammatory events such as cell migration, chemotaxis, phagocytosis and respiratory burst. While many studies have shown that binding to FPR2 is a chemotactic signal to attract macrophages to the site of tissue injury, other studies have highlighted that it is part of an anti-inflammatory process. For example, from some of the studies detailed below (summarized in [Figure 1]), it seems that activation of this receptor does not itself cause further production of pro-inflammatory mediators by macrophages. Instead, FPR2 appears to attract macrophages and other immune cells to the site of tissue injury to initiate a “quiet mopping-up process” to resolve inflammation.
Hepatic spheroids used as an in vitro model to study malaria relapse
Biomaterials. 2019 Sep;216:119221. doi: 10.1016/j.biomaterials.2019.05.032.
Chua ACY, Ananthanarayanan A, Ong JJY, Wong JY, Yip A, Singh NH, Qu Y, Dembele L, McMillian M, Ubalee R, Davidson S, Tungtaeng A, Imerbsin R, Gupta K, Andolina C, Lee F, S-W Tan K, Nosten F, Russell B, Lange A, Diagana TT, Rénia L, Yeung BKS, Yu H, Bifani P
Abstract
Hypnozoites are the liver stage non-dividing form of the malaria parasite that are responsible for relapse and acts as a natural reservoir for human malaria Plasmodium vivax and P. ovale as well as a phylogenetically related simian malaria P. cynomolgi. Our understanding of hypnozoite biology remains limited due to the technical challenge of requiring the use of primary hepatocytes and the lack of robust and predictive in vitro models. In this study, we developed a malaria liver stage model using 3D spheroid-cultured primary hepatocytes. The infection of primary hepatocytes in suspension led to increased infectivity of both P. cynomolgi and P. vivax infections. We demonstrated that this hepatic spheroid model was capable of maintaining long term viability, hepatocyte specific functions and cell polarity which enhanced permissiveness and thus, permitting for the complete development of both P. cynomolgi and P. vivax liver stage parasites in the infected spheroids. The model described here was able to capture the full liver stage cycle starting with sporozoites and ending in the release of hepatic merozoites capable of invading simian erythrocytes in vitro. Finally, we showed that this system can be used for compound screening to discriminate between causal prophylactic and cidal antimalarials activity in vitro for relapsing malaria.
Self‐assembling amyloid‐like peptides as exogenous second harmonic probes for bioimaging applications
Journal of Biophotonics. 2019 Jun 4:e201900065. doi: 10.1002/jbio.201900065.
Ni M, Zhuo S, Iliescu C, So PTC, Mehta JS, Yu H, Hauser CAE
Abstract
Amyloid‐like peptides are an ideal model for the mechanistic study of amyloidosis, which may lead to many human diseases, such as Alzheimer disease. This study reports a strong second harmonic generation (SHG) effect of amyloid‐like peptides, having a signal equivalent to or even higher than those of endogenous collagen fibers. Several amyloid‐like peptides (both synthetic and natural) were examined under SHG microscopy and shown they are SHG‐active. These peptides can also be observed inside cells (in vitro). This interesting property can make these amyloid‐like peptides second harmonic probes for bioimaging applications. Furthermore, SHG microscopy can provide a simple and label‐free approach to detect amyloidosis. Lattice corneal dystrophy was chosen as a model disease of amyloidosis. Morphological difference between normal and diseased human corneal biopsy samples can be easily recognized, proving that SHG can be a useful tool for disease diagnosis.
Studying nucleic envelope and plasma membrane mechanics of eukaryotic cells using confocal reflectance interferometric microscopy.
Nature Communications. 2019 Aug 13;10(1):3652. doi: 10.1038/s41467-019-11645-4.
Singh VR, Yang YA, Yu H, Kamm RD, Yaqoob Z, So PTC
Abstract
Mechanical stress on eukaryotic nucleus has been implicated in a diverse range of diseases including muscular dystrophy and cancer metastasis. Today, there are very few non-perturbative methods to quantify nuclear mechanical properties. Interferometric microscopy, also known as quantitative phase microscopy (QPM), is a powerful tool for studying red blood cell biomechanics. The existing QPM tools, however, have not been utilized to study biomechanics of complex eukaryotic cells either due to lack of depth sectioning, limited phase measurement sensitivity, or both. Here, we present depth-resolved confocal reflectance interferometric microscopy as the next generation QPM to study nuclear and plasma membrane biomechanics. The proposed system features multiple confocal scanning foci, affording 1.5 micron depth-resolution and millisecond frame rate. Furthermore, a near common-path interferometer enables quantifying nanometer-scale membrane fluctuations with better than 200 picometers sensitivity. Our results present accurate quantification of nucleic envelope and plasma membrane fluctuations in embryonic stem cells.
The Progress of Investigating the CD137-CD137L Axis as a Potential Target for Systemic Lupus Erythematosus.
Cells. 2019 Sep 6;8(9). pii: E1044. doi: 10.3390/cells8091044.
Mak A, Schwarz H
Abstract
Costimulatory molecules facilitate cross-talks among leukocytes via mutual stimulatory and inhibitory signalling, contributing to diverse immunological outcomes in normal physiological responses and pathological conditions. Systemic lupus erythematosus (SLE) is a complex multi-systemic autoimmune condition in which cellular communication through the involvement of costimulatory molecules is crucial in driving proinflammatory responses from the stage of autoantigen presentation to the subsequent process of pathogenic autoantibody production. While the physiology of the costimulatory systems including OX40-OX40L, CD28/CTLA-4-CD80/86, ICOS-B7RP1 and CD70-CD27 has been relatively well studied in SLE, recent data on the immunopathology of the CD137-CD137 ligand (CD137L) system in murine lupus models and patients with SLE highlight the critical role of this costimulatory system in initiating and perpetuating the diverse clinical and serological phenotypes of SLE. CD137, a membrane-bound receptor which belongs to the tumour necrosis factor receptor superfamily, is mainly expressed on activated T cells. Activation of the CD137 receptor via its interaction with CD137L which is expressed on antigen present cells (APC) including B cells, triggers bi-directional signalling; that is, signalling through CD137 as well as signalling through CD137L (reverse signalling), which further activates T cells and polarizes them to the Th1/Tc1 pathway. Further, via reverse CD137L signalling it enhances differentiation and maturation of the APC, particularly of dendritic cells, which subsequently drive proinflammatory cytokine production. In this review, recent data including our experience in the manipulation of CD137L signalling pertaining to the pathophysiology of SLE will be critically reviewed. More in-depth understanding of the biology of the CD137-CD137L co-stimulation system opens an opportunity to identify new prognostic biomarkers and the design of novel therapeutic approaches for advancing the management of SLE.
Deletion of CD137 Ligand Exacerbates Renal and Cutaneous but Alleviates Cerebral Manifestations in Lupus.
Frontiers in Immunology. 2019 Jun 26;10:1411. doi: 10.3389/fimmu.2019.01411. eCollection 2019.
Mak A, Dharmadhikari B, Kow NY, Thamboo TP, Tang Q, Wong LW, Sajikumar S, Wong HY, Schwarz H.
Abstract
The CD137—CD137 ligand (CD137L) costimulatory system is a critical immune checkpoint with pathophysiological implications in autoimmunity. In this study, we investigated the role of CD137L-mediated costimulation on renal, cutaneous and cerebral manifestations in lupus and the underlying immunological mechanism. Lupus-prone C57BL/6lpr−/− (B6.lpr) mice were crossed to C57BL/6.CD137L−/− mice to obtain CD137L-deficient B6.lpr [double knock out (DKO)] mice. We investigated the extent of survival, glomerulonephritis, skin lesions, cerebral demyelination, immune deviation and long-term synaptic plasticity among the two mouse groups. Cytokine levels, frequency of splenic leukocyte subsets and phenotypes were compared between DKO, B6.lpr and B6.WT mice. A 22 month observation of 226 DKO and 137 B6.lpr mice demonstrated significantly more frequent proliferative glomerulonephritis, larger skin lesions and shorter survival in DKO than in B6.lpr mice. Conversely, microglial activation and cerebral demyelination were less pronounced while long-term synaptic plasticity, was superior in DKO mice. Splenic Th17 cells were significantly higher in DKO than in B6.lpr and B6.WT mice while Th1 and Th2 cell frequencies were comparable between DKO and B6.lpr mice. IL-10 and IL-17 expression by T cells was not affected but there were fewer IL-10-producing myeloid (CD11b+) cells, and also lower serum IL-10 levels in DKO than in B6.lpr mice. The absence of CD137L causes an immune deviation toward Th17, fewer IL-10-producing CD11b+ cells and reduced serum IL-10 levels which potentially explain the more severe lupus in DKO mice while leading to reduced microglia activation, lesser cerebral damage and less severe neurological deficits.
Increased Akt-Driven Glycolysis Is the Basis for the Higher Potency of CD137L-DCs.
Frontiers in Immunology. 2019 Jun 26;10:1411. doi: 10.3389/fimmu.2019.01411. eCollection 2019.
Zeng Q, Mallilankaraman K, Schwarz H.
Abstract
CD137 ligand-induced dendritic cells (CD137L-DCs) are a new type of dendritic cells (DCs) that induce strong cytotoxic T cell responses. Investigating the metabolic activity as a potential contributing factor for their potency, we find a significantly higher rate of glycolysis in CD137L-DCs than in granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 4 induced monocyte-derived DCs (moDCs). Using unbiased screening, Akt-mTORC1 activity was found to be significantly higher throughout the differentiation and maturation of CD137L-DCs than that of moDCs. Furthermore, this higher activity of the Akt-mTORC1 pathway is responsible for the significantly higher glycolysis rate in CD137L-DCs than in moDCs. Inhibition of Akt during maturation or inhibition of glycolysis during and after maturation resulted in suppression of inflammatory DCs, with mature CD137L-DCs being the most affected ones. mTORC1, instead, was indispensable for the differentiation of both CD137L-DCs and moDCs. In contrast to its role in supporting lipid synthesis in murine bone marrow-derived DCs (BMDCs), the higher glycolysis rate in CD137L-DCs does not lead to a higher lipid content but rather to an accumulation of succinate and serine. These data demonstrate that the increased Akt-driven glycolysis underlies the higher activity of CD137L-DCs.
Epstein-Barr virus-encoded LMP1 induces ectopic CD137 expression on Hodgkin and Reed-Sternberg cells via the PI3K-AKT-mTOR pathway.
Leukemia & Lymphoma. 2019 May 6:1-8. doi: 10.1080/10428194.2019.1607330. [Epub ahead of print]
Priya Aravinth S, Rajendran S, Li Y, Wu M, Yi Wong AH, Schwarz H.
Abstract
CD137 is a potent co-stimulatory molecule on activated T cells, and its ligand (CD137L) is expressed on antigen presenting cells (APC). Ectopic expression of CD137 has been identified on Hodgkin Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin Lymphoma (HL), and CD137 on HRS cells was found to support growth of HRS cells and escape from immune surveillance. HRS cells are mostly derived from B cells, which poses the question of how B cells acquire ectopic CD137 expression during the transformation process. HL is associated with Epstein-Barr virus (EBV) infection. We show that the EBV latent membrane protein 1 (LMP1) induces expression of CD137 in HRS cell lines. In a HL tissue microarray, 96% of the CD137-positive HL cases stained positive for LMP1. LMP1 utilizes the PI3K-AKT-mTOR pathway for inducing CD137 expression. These findings support the role of EBV in HL pathogenesis.
Mitochondria-Targeted Two-Photon Fluorescent Photosensitizers for Cancer Cell Apoptosis via Spatial Selectability.
Adv Healthc Mater. 2019 Jul;8(14):e1900212. doi: 10.1002/adhm.201900212. Epub 2019 May 13.
Ni Y, Zhang H, Chai C, Peng B, Zhao A, Zhang J, Li L, Zhang C, Ma B, Bai H, Lim KL, Huang W
Abstract
Organelle-targeted photosensitizers have been reported to be effective cell apoptosis agents. Mitochondria is recognized as an ideal target for cancer treatment due to its central role in oxidative metabolism and apoptosis. Meanwhile, two-photon (TP) fluorescence microscopy has become a powerful tool for fluorescence imaging in biological events based on its minimizing photodamage/photobleaching and intrinsic 3D resolution in deep tissues and in vivo. In this study, a series of novel mitochondrial-targeted TP fluorescent photosensitizers (TP-tracers) are designed, synthesized, and systematically investigated. These TP-tracers exhibit extraordinary anti-interference capability among different cations, anions, and amino acids as well as the insensitivity to the changes of pH and complex biological environments. TP-tracers are further used in fluorescence living cells, Drosophila brains, and zebrafish imaging with low cytotoxicity, excellent mitochondria-targeting, and TP properties. The results demonstrate efficient mitochondria-targeting cell selective apoptosis based on TP-activated cancer cells with highly single cell selectivity, and the pharmacokinetic study reveals that MitoY2 does not have accumulation in rats. It is believed that these molecules hold great potential in TP-related smart phototherapy.
Visualization of Intra-neuronal Motor Protein Transport through Upconversion Microscopy.
Zeng X, Chen S, Weitemier A, Han S, Blasiak A, Prasad A, Zheng K, Yi Z, Luo B, Yang IH, Thakor N, Chai C, Lim KL, McHugh TJ, All AH, Liu X.
Abstract
Cargo transport along axons, a physiological process mediated by motor proteins, is essential for neuronal function and survival. A current limitation in the study of axonal transport is the lack of a robust imaging technique with a high spatiotemporal resolution to visualize and quantify the movement of motor proteins in real-time and in different depth planes. Herein, we present a dynamic imaging technique that fully exploits the characteristics of upconversion nanoparticles. This technique can be used as a microscopic probe for the quantitative in situ tracking of retrograde transport neurons with single-particle resolution in multilayered cultures. This study may provide a powerful tool to reveal dynamic neuronal activity and intra-axonal transport function as well as any associated neurodegenerative diseases resulting from mutation or impairment in the axonal transport machinery.
Cell signaling and fate through the redox lens.
Redox Biology. 2019 Aug 9:101298. doi: 10.1016/j.redox.2019.101298. [Epub ahead of print].
Pervaiz S.
Abstract
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A novel scoring system for pivotal autophagy-related genes predicts outcomes after chemotherapy in advanced ovarian cancer patients.
Niu Y, Sun W, Chen K, Fu Z, Chen Y, Zhu J, Chen H, Shi Y, Zhang H, Wang L, Shen HM, Xia D, Wu Y.
Abstract
BACKGROUND:
In the clinical practice of ovarian cancer, the application of autophagy, an important regulator of carcinogenesis and chemoresistance, is still limited. This study aimed to establish a scoring system based on expression profiles of pivotal autophagy-related (ATG) genes in stage III/IV ovarian cancer patients who received chemotherapy.
METHODS:
Data of ovarian serous cystadenocarcinoma in The Cancer Genome Atlas (TCGA-OV) were used as training dataset. Two validation datasets comprised patients in a Chinese local database and a dataset from the Gene Expression Omnibus (GEO). ATG genes significantly (P < 0.1) associated with overall survival (OS) were selected and aggregated into an ATG scoring scale, of which the abilities to predict OS and recurrence-free survival (RFS) were examined.
RESULTS:
43 autophagy-related genes were selected to develop the ATG score. In TCGA-OV, patients with lower ATG scores had better OS [hazard ratio, 0.41; 95% confidence interval (CI), 0.26-0.65; P < 0.001) and RFS (hazard ratio, 0.47; 95% CI, 0.27-0.82; P = 0.007). After complete or partial remission to primary therapy, the rate of recurrence was 47.2% in the low-score group and 68.3% in the high-score group (odds ratio, 0.42; 95% CI, 0.18-0.92; P = 0.03). Such findings were verified in the two validation datasets.
CONCLUSION:
We established a novel scoring system based on pivotal ATG genes, which accurately predicts the outcomes of advanced ovarian cancer patients after chemotherapy.
IMPACT:
The present ATG scoring system may provide a novel perspective and a promising tool for the development of personalized therapy in the future.
Targeted metabolomics reveals differential biological effects of nanoplastics and nanoZnO in human lung cells.
Nanotoxicology. 2019 Oct;13(8):1117-1132. doi: 10.1080/17435390.2019.1640913. Epub 2019 Jul 24.
Lim SL, Ng CT, Zou L, Lu Y, Chen J, Bay BH, Shen HM, Ong CN.
Abstract
Engineered nanomaterials are of public health concern. Recently, there has been an increasing attention on the toxicity of nanoplastics and nanoZnO because of their increasing utilization and presence in the environment. However, knowledge of their toxicological behavior and metabolic interactions with the cellular machinery that determine their potential health effects are extremely limited. In this study, the cellular uptake, cytotoxic effects, and metabolic responses of bronchus epithelial (BEAS-2B) cells exposed to nanopolystyrene (nanoPS) and a widely used metallic nanoparticle, nanoZnO, were investigated using a tandem mass spectrometry-based metabolomics approach. The results revealed that even with low cytotoxicity, these nanoparticles (NPs) affected cell metabolism. NanoPS exposure showed autophagic- and endoplasmic reticulum (ER) stress-related metabolic changes such as increased in amino acids and tricarboxylic acid cycle (TCA) intermediate metabolites, a process known to play a critical role in regulating cell resistance to cytotoxic effects. Both metabolomics profiling and ER-stress pathway, together with quantitative real-time RT-polymerase chain reaction (qRT-PCR) analyses, demonstrated that autophagy was reciprocally regulated to couple metabolic and transcriptional reprograming. In contrast, nanoZnO-induced ROS-mediated cell death was associated with mitochondrial dysfunction and interference in regulating energy metabolism. Collectively, these two types of NPs were observed to cause perturbations albeit differential in cellular metabolism associated with their cytotoxic effects. Our findings provided an in depth understanding of metabolic changes influenced by two different types of NPs, with contrasting molecular mechanisms for the adverse effects observed.
STX17 dynamically regulated by Fis1 induces mitophagy via hierarchical macroautophagic mechanism.
Nature Communications. 2019 May 3;10(1):2059. doi: 10.1038/s41467-019-10096-1.
Xian H, Yang Q, Xiao L, Shen HM, Liou YC.
Abstract
Mitophagy is the selective autophagic targeting and removal of dysfunctional mitochondria. While PINK1/Parkin-dependent mitophagy is well-characterized, PINK1/Parkin-independent route is poorly understood. Using structure illumination microscopy (SR-SIM), we demonstrate that the SNARE protein Syntaxin 17 (STX17) initiates mitophagy upon depletion of outer mitochondrial membrane protein Fis1. With proteomics analysis, we identify the STX17-Fis1 interaction, which controls the dynamic shuffling of STX17 between ER and mitochondria. Fis1 loss results in aberrant STX17 accumulation on mitochondria, which exposes the N terminus and promotes self-oligomerization to trigger mitophagy. Mitochondrial STX17 interacts with ATG14 and recruits core autophagy proteins to form mitophagosome, followed by Rab7-dependent mitophagosome-lysosome fusion. Furthermore, Fis1 loss impairs mitochondrial respiration and potentially sensitizes cells to mitochondrial clearance, which is mediated through canonical autophagy machinery, closely linking non-selective macroautophagy to mitochondrial turnover. Our findings uncover a PINK1/Parkin-independent mitophagic mechanism in which outer mitochondrial membrane protein Fis1 regulates mitochondrial quality control.
Lysosomal inhibition attenuates peroxisomal gene transcription via suppression of PPARA and PPARGC1A levels.
Autophagy. 2019 Aug;15(8):1455-1459. doi: 10.1080/15548627.2019.1609847. Epub 2019 Apr 28.
Siong Tan HW, Anjum B, Shen HM, Ghosh S, Yen PM, Sinha RA.
Abstract
Lysosomes influence dynamic cellular processes such as nutrient sensing and transcriptional regulation. To explore novel transcriptional pathways regulated by lysosomes, we performed microarray analysis followed by qPCR validation in a mouse hepatocyte cell line, AML12, treated with bafilomycin A1 (lysosomal v-type H+-translocating ATPase inhibitor). Pathway enrichment analysis revealed significant downregulation of gene sets related to peroxisomal biogenesis and peroxisomal lipid oxidation upon lysosomal inhibition. Mechanistically, pharmacological inhibition of lysosomes as well as genetic knockdown of Tfeb led to downregulation of the peroxisomal master regulator PPARA and its coactivator PPARGC1A/PGC1α. Consistently, ectopic induction of PPARA transcriptional activity rescues the effects of lysosomal inhibition on peroxisomal gene expression. Collectively, our results uncover a novel metabolic regulation of peroxisomes by lysosomes via PPARA-PPARGC1A transcriptional signalling. Abbreviations: Acox1: acyl-Coenzyme A oxidase 1, palmitoyl; Acot: acyl-CoA thioesterase; ACAA: acetyl-Coenzyme A acyltransferase; ABCD3/PMP70: ATP-binding cassette, sub-family D (ALD), member 3; BafA1: bafilomycin A1; Crot: carnitine O-octanoyltransferase; CTSB: cathepsin B; Decr2: 2-4-dienoyl-Coenzyme A reductase 2, peroxisomal; Ech1: enoyl coenzyme A hydratase 1, peroxisomal; Ehhadh: enoyl-Coenzyme A, hydratase/3-hydroxyacyl Coenzyme A dehydrogenase; FDR: false discovery rate; Hsd17b4: hydroxysteroid (17-beta) dehydrogenase 4; NES: normalized enrichment score; NOM: nominal; Pex: peroxin; PPARA: peroxisome proliferator activated receptor alpha; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; TFEB: transcription factor EB.
Manipulating energy migration within single lanthanide activator for switchable upconversion emissions towards bidirectional photoactivation.
Nature Communications. 2019 Sep 27;10(1):4416. doi: 10.1038/s41467-019-12374-4.
Mei Q, Bansal A, Jayakumar MKG, Zhang Z, Zhang J, Huang H, Yu D, Ramachandra CJA, Hausenloy DJ, Soong TW, Zhang Y.
Abstract
Reliance on low tissue penetrating UV or visible light limits clinical applicability of phototherapy, necessitating use of deep tissue penetrating near-infrared (NIR) to visible light transducers like upconversion nanoparticles (UCNPs). While typical UCNPs produce multiple simultaneous emissions for unidirectional control of biological processes, programmable control requires orthogonal non-overlapping light emissions. These can be obtained through doping nanocrystals with multiple activator ions. However, this requires tedious synthesis and produces complicated multi-shell nanoparticles with a lack of control over emission profiles due to activator crosstalk. Herein, we explore cross-relaxation (CR), a non-radiative recombination pathway typically perceived as deleterious, to manipulate energy migration within the same lanthanide activator ion (Er3+) towards orthogonal red and green emissions, simply by adjusting excitation wavelength from 980 to 808 nm. These UCNPs allow programmable activation of two synergistic light-gated ion channels VChR1 and Jaws in the same cell to manipulate membrane polarization, demonstrated here for cardiac pacing.
Intravenous Immunoglobulin (IVIg) Induce a Protective Phenotype in Microglia Preventing Neuronal Cell Death in Ischaemic Stroke.
Neuromolecular Medicine. 2019 Sep 26. doi: 10.1007/s12017-019-08571-5. [Epub ahead of print]
Häußler V, Daehn T, Rissiek B, Roth V, Gerloff C, Arumugam TV, Magnus T, Gelderblom M.
Abstract
Targeting the immune system and thereby modulating the inflammatory response in ischemic stroke has shown promising therapeutic potential in various preclinical trials. Among those, intravenous immunoglobulins (IVIg) have moved into the focus of attention. In a murine model of experimental stroke, we explored the therapeutic potential of IVIg on the neurological outcome and the inflammatory response. Further, we used an in vitro system to assess effects of IVIg-stimulated microglia on neuronal survival. Treatment with IVIg resulted in decreased lesion sizes, without significant effects on the infiltration and activation pattern of peripheral immune cells. However, in microglia IVIg induced a switch towards an upregulation of protective polarization markers, and the ablation of microglia led to the loss of neuroprotective IVIg effects. Functionally, IVIg stimulated microglia ameliorated neuronal cell death elicited by oxygen and glucose deprivation in vitro. Notably, application of IVIg in vivo led to a comparable decrease of apoptotic neurons in the penumbra area. Although neuroprotective effects of IVIg in vivo and in vitro have been established in previous studies, we were able to show for the first time, that IVIg modulates the polarization of microglia during the pathogenesis of stroke.
Peptidase neurolysin functions to preserve the brain after ischemic stroke in male mice.
Journal of Neurochemistry. 2019 Sep 5. doi: 10.1111/jnc.14864. [Epub ahead of print]
Jayaraman S, Al Shoyaib A, Kocot J, Villalba H, Alamri FF, Rashid M, Wangler NJ, Chowdhury EA, German N, Arumugam TV, Abbruscato TJ, Karamyan VT.
Abstract
Previous studies documented upregulation of peptidase neurolysin (Nln) after brain ischemia, however the significance of Nln function in the post-stroke brain remained unknown. The aim of this study was to assess the functional role of Nln in the brain after ischemic stroke. Administration of a specific Nln inhibitor Agaricoglyceride A (AgaA) to mice after stroke in a middle cerebral artery occlusion model (MCAO), dose-dependently aggravated injury measured by increased infarct and edema volumes, blood-brain barrier disruption, increased levels of IL-6 and MCP-1, neurological and motor deficit 24 h after stroke. In this setting, AgaA resulted in inhibition of Nln in the ischemic hemisphere leading to increased levels of Nln substrates bradykinin, neurotensin and substance P. AgaA lacked effects on several physiological parameters and appeared non-toxic to mice. In a reverse approach, we developed an adeno-associated viral vector (AAV2/5-CAG-Nln) to overexpress Nln in the mouse brain. Applicability of AAV2/5-CAG-Nln to transduce catalytically active Nln was confirmed in primary neurons and in vivo. Overexpression of Nln in the mouse brain was also accompanied by decreased levels of its substrates. Two weeks after in vivo transduction of Nln using the AAV vector, mice were subjected to MCAO and the same outcome measures were evaluated 72 h later. These experiments revealed that abundance of Nln in the brain protects animals from stroke. This study is the first to document functional significance of Nln in pathophysiology of stroke and provide evidence that Nln is an endogenous mechanism functioning to preserve the brain from ischemic injury.
Effect of fingolimod on oligodendrocyte maturation under prolonged cerebral hypoperfusion.
Brain Research. 2019 Oct 1;1720:146294. doi: 10.1016/j.brainres.2019.06.013. Epub 2019 Jun 12.
Yasuda K, Maki T, Saito S, Yamamoto Y, Kinoshita H, Choi YK, Arumugam TV, Lim YA, Chen CLH, Wong PT, Ihara M, Takahashi R.
Abstract
Oligodendrocytes (OLGs) support neuronal system and have crucial roles for brain homeostasis. As the renewal and regeneration of OLGs derived from oligodendrocyte precursor cells (OPCs) are inhibited by various pathological conditions, the restoration of impaired oligodendrogenesis is a therapeutic strategy for OLG-related diseases such as subcortical ischemic vascular dementia (SIVD). Fingolimod (FTY720), a drug for multiple sclerosis, is reported to elicit a cytoprotective effect on OPCs in vitro. However, the effects of fingolimod against ischemia-induced suppression of OPC differentiation remain unknown. Hence, the purpose of this study was to investigate the effectiveness of fingolimod against ischemia-induced suppression of oligodendrogenesis. For the in vitro experiments, primary rat cultured OPCs were incubated with a non-lethal concentration of CoCl2 to induce chemical hypoxic conditions and were treated with or without fingolimod-phosphate. We found that low concentration fingolimod-phosphate directly rescued ischemia-induced suppression of OPC differentiation via the phosphoinositide 3-kinase-Akt pathway. For the in vivo experiments, we used a mouse model of SIVD generated by bilateral common carotid artery stenosis. On day 28 after surgery, fingolimod ameliorated ischemia-induced demyelination and promoted oligodendrogenesis under prolonged cerebral hypoperfusion. The present study demonstrates that fingolimod can promote oligodendrogenesis under ischemic conditions and may be a therapeutic candidate for SIVD.
Zika virus alters DNA methylation status of genes involved in Hippo signaling pathway in human neural progenitor cells.
Epigenomics. 2019 Aug;11(10):1143-1161. doi: 10.2217/epi-2018-0180. Epub 2019 Jun 25.
Kandilya D, Maskomani S, Shyamasundar S, Tambyah PA, Shiao Yng C, Lee RCH, Hande MP, Mallilankaraman K, Chu JJH, Dheen ST.
Abstract
Aim: This study was aimed to understand if Zika virus (ZIKV) alters the DNA methylome of human neural progenitor cells (hNPCs). Materials & methods: Whole genome DNA methylation profiling was performed using human methylationEPIC array in control and ZIKV infected hNPCs. Results & conclusion: ZIKV infection altered the DNA methylation of several genes such as WWTR1 (TAZ) and RASSF1 of Hippo signaling pathway which regulates organ size during brain development, and decreased the expression of several centrosomal-related microcephaly genes, and genes involved in stemness and differentiation in human neural progenitor cells. Overall, ZIKV downregulated the Hippo signaling pathway genes which perturb the stemness and differentiation process in hNPCs, which could form the basis for ZIKV-induced microcephaly.
The Transcription Factor Bhlhe40 Programs Mitochondrial Regulation of Resident CD8+ T Cell Fitness and Functionality.
Immunity. 2019 Sep 17;51(3):491-507.e7. doi: 10.1016/j.immuni.2019.08.013.
Li C, Zhu B, Son YM, Wang Z, Jiang L, Xiang M, Ye Z, Beckermann KE, Wu Y, Jenkins JW, Siska PJ, Vincent BG, Prakash YS, Peikert T, Edelson BT, Taneja R, Kaplan MH, Rathmell JC, Dong H, Hitosugi T, Sun J.
Abstract
Tissue-resident memory CD8+ T (Trm) cells share core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic, and epigenetic regulation of Trm cell and TIL development and function is largely undefined. Here, we found that the transcription factor Bhlhe40 was specifically required for Trm cell and TIL development and polyfunctionality. Local PD-1 signaling inhibited TIL Bhlhe40 expression, and Bhlhe40 was critical for TIL reinvigoration following anti-PD-L1 blockade. Mechanistically, Bhlhe40 sustained Trm cell and TIL mitochondrial fitness and a functional epigenetic state. Building on these findings, we identified an epigenetic and metabolic regimen that promoted Trm cell and TIL gene signatures associated with tissue residency and polyfunctionality. This regimen empowered the anti-tumor activity of CD8+ T cells and possessed therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights into the local regulation of Trm cell and TIL function.
Ambient and supplemental magnetic fields promote myogenesis via a TRPC1-mitochondrial axis: evidence of a magnetic mitohormetic mechanism.
FASEB Journal. 2019 Sep 13:fj201900057R. doi: 10.1096/fj.201900057R. [Epub ahead of print]
Yap JLY, Tai YK, Fröhlich J, Fong CHH, Yin JN, Foo ZL, Ramanan S, Beyer C, Toh SJ, Casarosa M, Bharathy N, Kala MP, Egli M, Taneja R, Lee CN, Franco-Obregón A.
Abstract
We show that both supplemental and ambient magnetic fields modulate myogenesis. A lone 10 min exposure of myoblasts to 1.5 mT amplitude supplemental pulsed magnetic fields (PEMFs) accentuated in vitro myogenesis by stimulating transient receptor potential (TRP)-C1-mediated calcium entry and downstream nuclear factor of activated T cells (NFAT)-transcriptional and P300/CBP-associated factor (PCAF)-epigenetic cascades, whereas depriving myoblasts of ambient magnetic fields slowed myogenesis, reduced TRPC1 expression, and silenced NFAT-transcriptional and PCAF-epigenetic cascades. The expression levels of peroxisome proliferator-activated receptor γ coactivator 1α, the master regulator of mitochondriogenesis, was also enhanced by brief PEMF exposure. Accordingly, mitochondriogenesis and respiratory capacity were both enhanced with PEMF exposure, paralleling TRPC1 expression and pharmacological sensitivity. Clustered regularly interspaced short palindromic repeats-Cas9 knockdown of TRPC1 precluded proliferative and mitochondrial responses to supplemental PEMFs, whereas small interfering RNA gene silencing of TRPM7 did not, coinciding with data that magnetoreception did not coincide with the expression or function of other TRP channels. The aminoglycoside antibiotics antagonized and down-regulated TRPC1 expression and, when applied concomitantly with PEMF exposure, attenuated PEMF-stimulated calcium entry, mitochondrial respiration, proliferation, differentiation, and epigenetic directive in myoblasts, elucidating why the developmental potential of magnetic fields may have previously escaped detection. Mitochondrial-based survival adaptations were also activated upon PEMF stimulation. Magnetism thus deploys an authentic myogenic directive that relies on an interplay between mitochondria and TRPC1 to reach fruition.-Yap, J. L. Y., Tai, Y. K., Fröhlich, J., Fong, C. H. H., Yin, J. N., Foo, Z. L., Ramanan, S., Beyer, C., Toh, S. J., Casarosa, M., Bharathy, N., Kala, M. P., Egli, M., Taneja, R., Lee, C. N., Franco-Obregón, A. Ambient and supplemental magnetic fields promote myogenesis via a TRPC1-mitochondrial axis: evidence of a magnetic mitohormetic mechanism.
Bhlhe40 and Bhlhe41 transcription factors regulate alveolar macrophage self-renewal and identity.
EMBO Journal. 2019 Aug 15:e101233. doi: 10.15252/embj.2018101233. [Epub ahead of print]
Rauschmeier R, Gustafsson C, Reinhardt A, A-Gonzalez N, Tortola L, Cansever D, Subramanian S, Taneja R, Rossner MJ, Sieweke MH, Greter M, Månsson R, Busslinger M, Kreslavsky T.
Abstract
Tissues in multicellular organisms are populated by resident macrophages, which perform both generic and tissue-specific functions. The latter are induced by signals from the microenvironment and rely on unique tissue-specific molecular programs requiring the combinatorial action of tissue-specific and broadly expressed transcriptional regulators. Here, we identify the transcription factors Bhlhe40 and Bhlhe41 as novel regulators of alveolar macrophages (AMs)-a population that provides the first line of immune defense and executes homeostatic functions in lung alveoli. In the absence of these factors, AMs exhibited decreased proliferation that resulted in a severe disadvantage of knockout AMs in a competitive setting. Gene expression analyses revealed a broad cell-intrinsic footprint of Bhlhe40/Bhlhe41 deficiency manifested by a downregulation of AM signature genes and induction of signature genes of other macrophage lineages. Genome-wide characterization of Bhlhe40 DNA binding suggested that these transcription factors directly repress the expression of lineage-inappropriate genes in AMs. Taken together, these results identify Bhlhe40 and Bhlhe41 as key regulators of AM self-renewal and guardians of their identity.
Integrin α7 expression is increased in asthmatic patients and its inhibition reduces Kras protein abundance in airway smooth muscle cells.
Scientific Reports. 2019 Jul 9;9(1):9892. doi: 10.1038/s41598-019-46260-2.
Teoh CM, Tan SSL, Langenbach SY, Wong AH, Cheong DHJ, Tam JKC, New CS, Tran T.
Abstract
Airway smooth muscle (ASM) cells exhibit plastic phenotypic behavior marked by reversible modulation and maturation between contractile and proliferative phenotypic states. Integrins are a class of transmembrane proteins that have been implicated as novel therapeutic targets for asthma treatment. We previously showed that integrin α7 is a novel marker of the contractile ASM phenotype suggesting that targeting this protein may offer new avenues to counter the increase in ASM cell mass that underlies airways hyperresponsiveness (AHR) in asthma. We now determine whether inhibition of integrin α7 expression would revert ASM cells back to a proliferative phenotype to cause an increase in ASM cell mass. This would be detrimental to asthmatic patients who already exhibit increased ASM mass in their airways. Using immunohistochemical analysis of the Melbourne Epidemiological Study of Childhood Asthma (MESCA) cohort, we show for the first time that integrin α7 expression in patients with severe asthma is increased, supporting a clinically relevant role for this protein in asthma pathophysiology. Moreover, inhibition of the laminin-integrin α7 signaling axis results in a reduction in smooth muscle-alpha actin abundance and does not revert ASM cells back to a proliferative phenotype. We determined that integrin α7-induced Kras isoform of p21 Ras acts as a point of convergence between contractile and proliferative ASM phenotypic states. Our study provides further support for targeting integrin α7 for the development of novel anti-asthma therapies.
Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems.
Biomolecules. 2019 Sep 25;9(10). pii: E530. doi: 10.3390/biom9100530.
Tavakol S, Ashrafizadeh M, Deng S, Azarian M, Abdoli A, Motavaf M, Poormoghadam D, Khanbabaei H, Afshar EG, Mandegary A, Pardakhty A, Yap CT, Mohammadinejad R, Kumar AP.
Abstract
Autophagy modulation is considered to be a promising programmed cell death mechanism to prevent and cure a great number of disorders and diseases. The crucial step in designing an effective therapeutic approach is to understand the correct and accurate causes of diseases and to understand whether autophagy plays a cytoprotective or cytotoxic/cytostatic role in the progression and prevention of disease. This knowledge will help scientists find approaches to manipulate tumor and pathologic cells in order to enhance cellular sensitivity to therapeutics and treat them. Although some conventional therapeutics suffer from poor solubility, bioavailability and controlled release mechanisms, it appears that novel nanoplatforms overcome these obstacles and have led to the design of a theranostic-controlled drug release system with high solubility and active targeting and stimuli-responsive potentials. In this review, we discuss autophagy modulators-related signaling pathways and some of the drug delivery strategies that have been applied to the field of therapeutic application of autophagy modulators. Moreover, we describe how therapeutics will target various steps of the autophagic machinery. Furthermore, nano drug delivery platforms for autophagy targeting and co-delivery of autophagy modulators with chemotherapeutics/siRNA, are also discussed.
FUS-mediated dysregulation of Sema5a, an autism-related gene, in FUS mice with hippocampus-dependent cognitive deficits.
Human Molecular Genetics. 2019 Sep 11. pii: ddz217. doi: 10.1093/hmg/ddz217. [Epub ahead of print]
Ho WY, Chang JC, Tyan SH, Yen YC, Lim K, Tan BSY, Ong J, Tucker-Kellogg G, Wong P, Koo E, Ling SC.
Abstract
Pathological FUS inclusions are found in 10% of patients with frontotemporal dementia (FTD) and those with amyotrophic lateral sclerosis (ALS) carrying FUS mutations. Current work indicates that FUS mutations may incur gain-of-toxic functions to drive ALS pathogenesis. However, how FUS dysfunction may affect cognition remains elusive. Using a mouse model expressing wild-type human FUS mimicking the endogenous expression pattern and level within the central nervous system, we found that they developed hippocampus-mediated cognitive deficits accompanied by an age-dependent reduction in spine density and long-term potentiation (LTP) in their hippocampus. However, there were no apparent FUS aggregates, nuclear envelope defects and cytosolic FUS accumulation. These suggest that these proposed pathogenic mechanisms may not be the underlying causes for the observed cognitive deficits. Unbiased transcriptomic analysis identified expression changes in a small set of genes with preferential expression in the neurons and oligodendrocyte lineage cells. Of these, we focused on Sema5a, a gene involved in axon guidance, spine dynamics, Parkinson’s disease and autism spectrum disorders. Critically, FUS binds directly to Sema5a mRNA and regulates Sema5a expression in a FUS-dose-dependent manner. Taken together, our data suggest that FUS-driven Sema5a deregulation may underlie the cognitive deficits in FUS transgenic mice.
C9orf72 intermediate repeats are associated with corticobasal degeneration, increased C9orf72 expression and disruption of autophagy.
Acta Neuropathologica. 2019 Jul 20. doi: 10.1007/s00401-019-02045-5. [Epub ahead of print]
Cali CP, Patino M, Tai YK, Ho WY, McLean CA, Morris CM, Seeley WW, Miller BL, Gaig C, Vonsattel JPG, White CL, Roeber S, Kretzschmar H, Troncoso JC, Troakes C, Gearing M, Ghetti B, Van Deerlin VM, Lee VM, Trojanowski JQ, Mok KY, Ling H, Dickson DW, Schellenberg GD, Ling SC, Lee EB.
Abstract
Microsatellite repeat expansion disease loci can exhibit pleiotropic clinical and biological effects depending on repeat length. Large expansions in C9orf72 (100s-1000s of units) are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). However, whether intermediate expansions also contribute to neurodegenerative disease is not well understood. Several studies have identified intermediate repeats in Parkinson’s disease patients, but the association was not found in autopsy-confirmed cases. We hypothesized that intermediate C9orf72 repeats are a genetic risk factor for corticobasal degeneration (CBD), a neurodegenerative disease that can be clinically similar to Parkinson’s but has distinct tau protein pathology. Indeed, intermediate C9orf72 repeats were significantly enriched in autopsy-proven CBD (n = 354 cases, odds ratio = 3.59, p = 0.00024). While large C9orf72 repeat expansions are known to decrease C9orf72 expression, intermediate C9orf72 repeats result in increased C9orf72 expression in human brain tissue and CRISPR/cas9 knockin iPSC-derived neural progenitor cells. In contrast to cases of FTD/ALS with large C9orf72 expansions, CBD with intermediate C9orf72 repeats was not associated with pathologic RNA foci or dipeptide repeat protein aggregates. Knock-in cells with intermediate repeats exhibit numerous changes in gene expression pathways relating to vesicle trafficking and autophagy. Additionally, overexpression of C9orf72 without the repeat expansion leads to defects in autophagy under nutrient starvation conditions. These results raise the possibility that therapeutic strategies to reduce C9orf72 expression may be beneficial for the treatment of CBD.
Elevated FUS levels by overriding its autoregulation produce gain-of-toxicity properties that disrupt protein and RNA homeostasis.
Autophagy. 2019 Sep;15(9):1665-1667. doi: 10.1080/15548627.2019.1633162. Epub 2019 Jun 23.
Ho WY, Ling SC.
Abstract
Coding or non-coding mutations in FUS (fused in sarcoma) cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In addition to familial ALS, abnormal aggregates of FUS are present in a portion of FTD and other neurodegenerative diseases independent of their mutations. Broad expression within the central nervous system of either wild-type or two ALS-linked human FUS mutants produces progressive motor phenotypes accompanied by characteristic ALS-like pathology. FUS levels are autoregulated to maintain an optimal steady-state level. Increasing FUS expression by saturating its autoregulatory mechanism results in rapidly progressive neurological phenotypes and dose-dependent lethality. Genome-wide expression analysis reveals genetic mis-regulations distinct from those via FUS reduction. Among these are increased expression of lysosomal proteins, suggestive of disruption in protein homeostasis as a potential gain-of-toxicity mechanism. Indeed, increased expression of wild-type FUS or ALS-linked mutant forms of FUS inhibit macroautophagy/autophagy. Collectively, our results demonstrate that: (1) mice expressing FUS develop progressive motor deficits, (2) increased FUS expression by overriding its autoregulatory mechanism accelerates neurodegeneration, providing a basis for FUS involvement without mutation, and (3) disruption in both protein homeostasis and RNA processing contribute to FUS-mediated toxicity.
Increased expression of heme-binding protein 1 early in Alzheimer’s disease is linked to neurotoxicity
eLife. 2019 Aug 27;8:e47498. doi: 10.7554/eLife.47498.
Yagensky O, Kohansal-Nodehi M, Gunaseelan S, Rabe T, Zafar S, Zerr I, Haertig W, Urlaub H, Chua JJE
Abstract
Alzheimer’s disease is the most prevalent neurodegenerative disorder leading to progressive cognitive decline. Despite decades of research, understanding AD progression at the molecular level, especially at its early stages, remains elusive. Here, we identified several presymptomatic AD markers by investigating brain proteome changes over the course of neurodegeneration in a transgenic mouse model of AD (3×Tg-AD). We show that one of these markers, heme-binding protein 1 (Hebp1), is elevated in the brains of both 3×Tg-AD mice and patients affected by rapidly-progressing forms of AD. Hebp1, predominantly expressed in neurons, interacts with the mitochondrial contact site complex (MICOS) and exhibits a perimitochondrial localization. Strikingly, wildtype, but not Hebp1-deficient, neurons showed elevated cytotoxicity in response to heme-induced apoptosis. Increased survivability in Hebp1-deficient neurons is conferred by blocking the activation of the mitochondrial-associated caspase signaling pathway. Taken together, our data highlight a role of Hebp1 in progressive neuronal loss during AD progression.
A feedforward relationship between active Rac1 and phosphorylated Bcl-2 is critical for sustaining Bcl-2 phosphorylation and promoting cancer progression
Cancer Lett. 2019 Aug 10;457:151-167. DOI: 10.1016/j.canlet.2019.05.009.
Chong SJF, Lai JXH, Qu J, Hirpara J, Kang J, Swaminathan K, Loh T, Kumar A, Vali S, Abbasi T, Pervaiz S.
Abstract
Active GTPase-Rac1 is associated with cellular processes involved in carcinogenesis and expression of Bcl-2 endows cells with the ability to evade apoptosis. Here we provide evidence that active Rac1 and Bcl-2 work in a positive feedforward loop to promote sustained phosphorylation of Bcl-2 at serine-70 (S70pBcl-2), which stabilizes its anti-apoptotic activity. Pharmacological and genetic inactivation of Rac1 prevent interaction with Bcl-2 and reduce S70pBcl-2. Similarly, BH3-mimetic inhibitors of Bcl-2 could disrupt Rac1-Bcl-2 interaction and reduce S70pBcl-2. This effect of active Rac1 could also be rescued by scavengers of intracellular superoxide (O2.−), thus implicating NOX-activating activity of Rac1 in promoting S70pBcl-2. Moreover, active Rac1-mediated redox-dependent S70pBcl-2 involves the inhibition of phosphatase PP2A holoenzyme assembly. Sustained S70pBcl-2 in turn secures Rac1/Bcl-2 interaction. Importantly, inhibiting Rac1 activity, scavenging O2.− or employing BH3-mimetic inhibitor significantly reduced S70pBcl-2-mediated survival in cancer cells. Notably, Rac1 expression, and its interaction with Bcl-2, positively correlate with S70pBcl-2 levels in patient-derived lymphoma tissues and with advanced stage lymphoma and melanoma. Together, we provide evidence of a positive feedforward loop involving active Rac1, S70pBcl-2 and PP2A, which could have potential diagnostic, prognostic and therapeutic implications.
Metabolic reprogramming of oncogene-addicted cancer cells to OXPHOS as a mechanism of drug resistance
Redox Biol. 2018 Dec 17:101076. DOI: 10.1016/j.redox.2018.101076.
Hirpara J, Eu JQ, Tan JKM, Wong AL, Clement MV, Kong LR, Ohi N, Tsunoda T, Qu J, Goh BC, Pervaiz S.
Abstract
The ability to selectively eradicate oncogene-addicted tumors while reducing systemic toxicity has endeared targeted therapies as a treatment strategy. Nevertheless, development of acquired resistance limits the benefits and durability of such a regime. Here we report evidence of enhanced reliance on mitochondrial oxidative phosphorylation (OXPHOS) in oncogene-addicted cancers manifesting acquired resistance to targeted therapies. To that effect, we describe a novel OXPHOS targeting activity of the small molecule compound, OPB-51602 (OPB). Of note, a priori treatment with OPB restored sensitivity to targeted therapies. Furthermore, cancer cells exhibiting stemness markers also showed selective reliance on OXPHOS and enhanced sensitivity to OPB. Importantly, in a subset of patients who developed secondary resistance to EGFR tyrosine kinase inhibitor (TKI), OPB treatment resulted in decrease in metabolic activity and reduction in tumor size. Collectively, we show here a switch to mitochondrial OXPHOS as a key driver of targeted drug resistance in oncogene-addicted cancers. This metabolic vulnerability is exploited by a novel OXPHOS inhibitor, which also shows promise in the clinical setting.
Gene expression analysis of heat-shock proteins and redox regulators reveals combinatorial prognostic markers in carcinomas of the gastrointestinal tract.
Redox Biol. 2018 Nov 29. pii: S2213-2317(18)30928-5. DOI: 10.1016/j.redox.2018.11.018.
Pohl SÖ, Pervaiz S, Dharmarajan A, Agostino M.
Abstract
Heat shock proteins (HSPs) are a large family of ubiquitously expressed proteins with diverse functions, including protein assembly and folding/unfolding. These proteins have been associated with the progression of various gastrointestinal tumours. Dysregulation of cellular redox has also been associated with gastrointestinal carcinogenesis, however, a link between HSPs and dysregulation of cellular redox in carcinogenesis remains unclear. In this study, we analysed mRNA co-expression and methylation patterns, as well as performed survival analysis and gene set enrichment analysis, on gastrointestinal cancer data sets (oesophageal, stomach and colorectal carcinomas) to determine whether HSP activity and cellular redox dysregulation are linked. A widespread relationship between HSPs and cellular redox was identified, with specific combinatorial co-expression patterns demonstrated to significantly alter patient survival outcomes. This comprehensive analysis provides the foundation for future studies aimed at deciphering the mechanisms of cooperativity between HSPs and redox regulatory enzymes, which may be a target for future therapeutic intervention for gastrointestinal tumours.
MnSOD is implicated in accelerated wound healing upon Negative Pressure Wound Therapy (NPWT): A case in point for MnSOD mimetics as adjuvants for wound management
Redox Biol. 2019 Jan;20:307-320. DOI: 10.1016/j.redox.2018.10.014.
Bellot GL, Dong X, Lahiri A, Sebastin SJ, Batinic-Haberle I, Pervaiz S, Puhaindran ME.
Abstract
Negative Pressure Wound Therapy (NPWT), a widely used modality in the management of surgical and trauma wounds, offers clear benefits over conventional wound healing strategies. Despite the wide-ranging effects ascribed to NPWT, the precise molecular mechanisms underlying the accelerated healing supported by NPWT remains poorly understood. Notably, cellular redox status-a product of the balance between cellular reactive oxygen species (ROS) production and anti-oxidant defense systems-plays an important role in wound healing and dysregulation of redox homeostasis has a profound effect on wound healing. Here we investigated potential links between the use of NPWT and the regulation of antioxidant mechanisms. Using patient samples and a rodent model of acute injury, we observed a significant accumulation of MnSOD protein as well as higher enzymatic activity in tissues upon NPWT. As a proof of concept and to outline the important role of SOD activity in wound healing, we replaced NPWT by the topical application of a MnSOD mimetic, Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP5+, MnE, BMX-010, AEOl10113) in the rodent model. We observed that MnE is a potent wound healing enhancer as it appears to facilitate the formation of new tissue within the wound bed and consequently advances wound closure by two days, compared to the non-treated animals. Taken together, these results show for the first time a link between NPWT and regulation of antioxidant mechanism through the maintenance of MnSOD activity. Additionally this discovery outlined the potential role of MnSOD mimetics as topical agents enhancing wound healing.
Redox Dichotomy in Cell Fate Decision: Evasive Mechanism or Achilles Heel?
Antioxid Redox Signal. 2018 Nov 1;29(13):1191-1195. DOI: 10.1089/ars.2018.7586.
Pervaiz S.
Abstract
Cellular redox state is a consequence of the balance between the rates of reactive oxygen species and/or reactive nitrogen species, and their dissipation via enzymatic and nonenzymatic redox buffering systems. While low levels of oscillation are associated with normal cellular metabolism, stimuli that favor a significant shift in the redox microenvironment, through either the increased production and/or compromise of the antioxidant defenses, induce overt oxidative stress. This change in the redox set point triggers a host of cellular responses ranging from modifications in cellular macromolecules, organelle morphology and physiology, amplified cell-to-cell and intracellular signaling, and changes in genome, epigenome, and proteome. The consequence of this dysregulated cellular homeostasis is therefore manifested in the form of a plethora of pathological states such as inflammation, diabetes mellitus, neurodegenerative disorders, atherosclerosis, and cancer. On the backdrop of these observations, this Forum attempts at reviewing the current understanding of how a prooxidant intracellular milieu favors cell survival while overt oxidative stress results in death execution, and the translation of these biological effects in human disease states, in particular cancer. The far-reaching biochemical, biological, and clinical ramifications of an altered redox environment are also discussed from the standpoint of strategic therapeutic design against refractory and aggressive cancers. It is tempting to conjecture if the inherent or acquired redox heterogeneity, at least in the case of cancer, has evolved as an “evasive mechanism,” or presents itself as the “Achilles heel” for therapeutic exploitation.
Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.
Biomaterials. 2019 May;201:16-32. DOI: 10.1016/j.biomaterials.2019.01.046. Epub 2019 Feb 6.
Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.
Abstract
Interconnected macroporous hydrogel is hydrophilic; it exhibits soft tissue-like mechanical property and aqueous-stable macroporosity for 3D spheroid culture. There is an unmet need to develop cleavable macroporous hydrogel, for the ease of retrieving functional spheroids for further in vitro and in vivo applications. We have developed and comprehensively characterized a hydroxypropyl-cellulose-disulfide sponge by systematically identifying strategies and synthesis schemes to confer cleavability to the sponge under cell-friendly conditions. It preserved the essential advantages of the macroporous hydrogel to support 3D spheroid formation and maintenance of sensitive hepatocytes while allowing rapid cleavage and retrieval of functional spheroids. By culturing HepaRG as spheroids in the cleavable sponge, we have accelerated HepaRG differentiation to 9 days compared to 28 days in 2D culture. Cytochrome P450 basal activity reached significantly higher level, while albumin secretion and fluorescein diacetate staining indicated the same at day 5. The purity of albumin+ hepatocytes reached 92.9% versus 7.1% of CK19+ cholangiocytes at day 9, a much stronger preference for hepatocytes than the 60% albumin+ hepatocytes purity in 2D culture. HepaRG differentiated hepatocytes were retrieved by cleaving the sponge with 10 mM tris-(2-carboxyethyl)-phosphine (TCEP) within 30 min preserving viability, plateability and positive albumin staining of the hepatocyte spheroids. This cleavable macroporous hydrogel sponge will support the rapid development of various 3D spheroid- or organoid-based applications in basic research and drug testing.
NRF2/ARE pathway negatively regulates BACE1 expression and ameliorates cognitive deficits in mouse Alzheimer’s models.
Bahn G, Park JS, Yun UJ, Lee YJ, Choi Y, Park JS, Baek SH, Choi BY, Cho YS, Kim HK, Han J, Sul JH, Baik SH, Lim J, Wakabayashi N, Bae SH, Han JW, Arumugam TV, Mattson MP, Jo DG.
Abstract
BACE1 is the rate-limiting enzyme for amyloid-β peptides (Aβ) generation, a key event in the pathogenesis of Alzheimer’s disease (AD). By an unknown mechanism, levels of BACE1 and a BACE1 mRNA-stabilizing antisense RNA (BACE1-AS) are elevated in the brains of AD patients, implicating that dysregulation of BACE1 expression plays an important role in AD pathogenesis. We found that nuclear factor erythroid-derived 2-related factor 2 (NRF2/NFE2L2) represses the expression of BACE1 and BACE1-AS through binding to antioxidant response elements (AREs) in their promoters of mouse and human. NRF2-mediated inhibition of BACE1 and BACE1-AS expression is independent of redox regulation. NRF2 activation decreases production of BACE1 and BACE1-AS transcripts and Aβ production and ameliorates cognitive deficits in animal models of AD. Depletion of NRF2 increases BACE1 and BACE1-AS expression and Aβ production and worsens cognitive deficits. Our findings suggest that activation of NRF2 can prevent a key early pathogenic process in AD.e in humans and IL-37tg mice, and may exert protective effects by modulating post-stroke inflammation in the brain and periphery.
IL-37 increases in patients after ischemic stroke and protects from inflammatory brain injury, motor impairment and lung infection in mice.
Sci Rep. 2019 May 6;9(1):6922.DOI: 10.1038/s41598-019-43364-7.
Zhang SR, Nold MF, Tang SC, Bui CB, Nold CA, Arumugam TV, Drummond GR, Sobey CG, Kim HA.
Abstract
Post-stroke inflammation may contribute to secondary brain injury and systemic immunosuppression. Interleukin(IL)-37 is an immunosuppressive cytokine belonging to the IL-1 superfamily with no mouse homologue yet identified, the effects of which have not been studied in stroke. Here we report: (1) the effect of ischemic stroke on circulating IL-37 in humans; and (2) the effect of IL-37 on stroke outcome measures in mice transgenic for human IL-37 (IL-37tg). We found that in the first 3 days after ischemic stroke in 55 patients, the plasma abundance of IL-37 was ~2-fold higher than in 24 controls. In IL-37tg mice, cerebral ischemia-reperfusion resulted in marked increases in plasma IL-37 (~9-fold) and brain IL-37 mRNA (~7,000-fold) at 24 h compared with sham-operated IL-37tg mice. Further, compared with wild-type (WT) mice subjected to cerebral ischemia-reperfusion, IL-37tg mice exhibited less severe locomotor deficit, smaller cerebral infarcts and reduced bacterial lung infection. In the ischemic hemisphere, there were 60% fewer pro-inflammatory microglia-macrophages and up to 4-fold higher expression of anti-inflammatory markers in IL-37tg compared to WT mice. Our data show that IL-37 expression is increased following ischemic stroke in humans and IL-37tg mice, and may exert protective effects by modulating post-stroke inflammation in the brain and periphery.
Cerebral transcriptome analysis reveals age-dependent progression of neuroinflammation in P301S mutant tau transgenic male mice.
Kim J, Selvaraji S, Kang SW, Lee WT, Chen CL, Choi H, Koo EH, Jo DG, Leong Lim K, Lim YA, Arumugam TV.
Abstract
Aggregation of the microtubule-associated protein, tau, can lead to neurofibrillary tangle formation in neurons and glia which is the hallmark of tauopathy. The cellular damage induced by the formation of neurofibrillary tangles leads to neuroinflammation and consecutive neuronal death. However, detailed observation of transcriptomic changes under tauopathy together with the comparison of age-dependent progression of neuroinflammatory gene expressions mediated by tau overexpression is required. Employing RNA sequencing on PS19 transgenic mice that overexpress human mutant tau harboring the P301S mutation, we have examined the effects of age-dependent tau overexpression on transcriptomic changes of immune and inflammatory responses in the cerebral cortex. Compared to age-matched wild type control, P301S transgenic mice exhibit significant transcriptomic alterations. We have observed age-dependent neuroinflammatory gene expression changes in both wild type and P301S transgenic mice where tau overexpression further promoted the expression of neuroinflammatory genes in 10-month old P301S transgenic mice. Moreover, functional gene network analyses (gene ontology and pathway enrichment) and prospective target protein interactions predicted the potential involvement of multiple immune and inflammatory pathways that may contribute to tau-mediated neuronal pathology. Our current study on P301S transgenic mice model revealed for the first time, the differences of gene expression patterns in both early and late stage of tau pathology in cerebral cortex. Our analyses also revealed that tau overexpression alone induces multiple inflammatory and immune transcriptomic changes and may provide a roadmap to elucidate the targets of anti-inflammatory therapeutic strategy focused on tau pathology and related neurodegenerative diseases.
SynGO: An Evidence-Based, Expert-Curated Knowledge Base for the Synapse.
Koopmans F, van Nierop P, Andres-Alonso M, Byrnes A, Cijsouw T, Coba MP, Cornelisse LN, Farrell RJ, Goldschmidt HL, Howrigan DP, Hussain NK, Imig C, de Jong APH, Jung H, Kohansalnodehi M, Kramarz B, Lipstein N, Lovering RC, MacGillavry H, Mariano V, Mi H, Ninov M, Osumi-Sutherland D, Pielot R, Smalla KH, Tang H, Tashman K, Toonen RFG, Verpelli C, Reig-Viader R, Watanabe K, van Weering J, Achsel T, Ashrafi G8, Asi N, Brown TC, De Camilli P, Feuermann M, Foulger RE, Gaudet P, Joglekar A, Kanellopoulos A, Malenka R, Nicoll RA, Pulido C, de Juan-Sanz J, Sheng M, Südhof TC, Tilgner HU, Bagni C, Bayés À, Biederer T, Brose N, Chua JJE, Dieterich DC, Gundelfinger ED, Hoogenraad C, Huganir RL, Jahn R, Kaeser PS, Kim E, Kreutz MR, McPherson PS, Neale BM, O’Connor V, Posthuma D, Ryan TA, Sala C, Feng G, Hyman SE, Thomas PD, Smit AB, Verhage M.
Abstract
Synapses are fundamental information-processing units of the brain, and synaptic dysregulation is central to many brain disorders (“synaptopathies”). However, systematic annotation of synaptic genes and ontology of synaptic processes are currently lacking. We established SynGO, an interactive knowledge base that accumulates available research about synapse biology using Gene Ontology (GO) annotations to novel ontology terms: 87 synaptic locations and 179 synaptic processes. SynGO annotations are exclusively based on published, expert-curated evidence. Using 2,922 annotations for 1,112 genes, we show that synaptic genes are exceptionally well conserved and less tolerant to mutations than other genes. Many SynGO terms are significantly overrepresented among gene variations associated with intelligence, educational attainment, ADHD, autism, and bipolar disorder and among de novo variants associated with neurodevelopmental disorders, including schizophrenia. SynGO is a public, universal reference for synapse research and an online analysis platform for interpretation of large-scale -omics data (https://syngoportal.org and http://geneontology.org).
Increased Akt-Driven Glycolysis Is the Basis for the Higher Potency of CD137L-DCs.
Front Immunol. 2019 Apr 24;10:868. DOI: 10.3389/fimmu.2019.00868. eCollection 2019.
Zeng Q, Mallilankaraman K, Schwarz H.
Abstract
CD137 ligand-induced dendritic cells (CD137L-DCs) are a new type of dendritic cells (DCs) that induce strong cytotoxic T cell responses. Investigating the metabolic activity as a potential contributing factor for their potency, we find a significantly higher rate of glycolysis in CD137L-DCs than in granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 4 induced monocyte-derived DCs (moDCs). Using unbiased screening, Akt-mTORC1 activity was found to be significantly higher throughout the differentiation and maturation of CD137L-DCs than that of moDCs. Furthermore, this higher activity of the Akt-mTORC1 pathway is responsible for the significantly higher glycolysis rate in CD137L-DCs than in moDCs. Inhibition of Akt during maturation or inhibition of glycolysis during and after maturation resulted in suppression of inflammatory DCs, with mature CD137L-DCs being the most affected ones. mTORC1, instead, was indispensable for the differentiation of both CD137L-DCs and moDCs. In contrast to its role in supporting lipid synthesis in murine bone marrow-derived DCs (BMDCs), the higher glycolysis rate in CD137L-DCs does not lead to a higher lipid content but rather to an accumulation of succinate and serine. These data demonstrate that the increased Akt-driven glycolysis underlies the higher activity of CD137L-DCs.
Epstein-Barr virus-encoded LMP1 induces ectopic CD137 expression on Hodgkin and Reed-Sternberg cells via the PI3K-AKT-mTOR pathway.
Leuk Lymphoma. 2019 May 6:1-8. DOI: 10.1080/10428194.2019.1607330. [Epub ahead of print]
Priya Aravinth S, Rajendran S, Li Y, Wu M, Yi Wong AH, Schwarz H.
Abstract
CD137 is a potent co-stimulatory molecule on activated T cells, and its ligand (CD137L) is expressed on antigen presenting cells (APC). Ectopic expression of CD137 has been identified on Hodgkin Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin Lymphoma (HL), and CD137 on HRS cells was found to support growth of HRS cells and escape from immune surveillance. HRS cells are mostly derived from B cells, which poses the question of how B cells acquire ectopic CD137 expression during the transformation process. HL is associated with Epstein-Barr virus (EBV) infection. We show that the EBV latent membrane protein 1 (LMP1) induces expression of CD137 in HRS cell lines. In a HL tissue microarray, 96% of the CD137-positive HL cases stained positive for LMP1. LMP1 utilizes the PI3K-AKT-mTOR pathway for inducing CD137 expression. These findings support the role of EBV in HL pathogenesis.
Induction of CD137 expression by viral genes reduces T cell costimulation.
J Cell Physiol. 2019 Apr 25. DOI: 10.1002/jcp.28710.
Wu M, Wong HY, Lin JL, Moliner A, Schwarz H.
Abstract
Intracellular pathogens are subject to elimination by a cellular immune response, and were therefore under evolutionary pressure to develop mechanisms that allow them to inhibit especially this arm of immunity. CD137, a T cell costimulatory molecule, and its ligand, CD137 ligand (CD137L), which is expressed on antigen presenting cells (APC), are potent drivers of cellular cytotoxic immune responses. Here, we report that different viruses usurp a negative feedback mechanism for the CD137-CD137L system that weakens cellular immune responses. Latent membrane protein (LMP)-1 and Tax, oncogenes of Epstein-Barr virus (EBV), and human T-cell lymphotropic virus (HTLV)-1, respectively, induce the expression of CD137. CD137 is transferred by trogocytosis to CD137L-expressing APC, and the CD137-CD137L complex is internalized and degraded, resulting in a reduced CD137-mediated T cell costimulation and a weakened cellular immune response which may facilitate the escape of the virus from immune surveillance. These data identify the usurpation of a CD137-based negative feedback mechanism by intracellular pathogens that enables them to reduce T cell costimulation.
Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis
Front Physiol. 2019 Feb 13;10:71. DOI: 10.3389/fphys.2019.00071. eCollection 2019.
Alhadad SB, Tan PMS, Lee JKW.
Abstract
Background: A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat, the rapid rise of body core temperature (T c ) often results in an impairment of exercise capacity and performance. As such, heat mitigation strategies such as aerobic fitness (AF), heat acclimation/acclimatization (HA), pre-exercise cooling (PC) and fluid ingestion (FI) can be introduced to counteract the debilitating effects of heat strain. We performed a meta-analysis to evaluate the effectiveness of these mitigation strategies using magnitude-based inferences. Methods: A computer-based literature search was performed up to 24 July 2018 using the electronic databases: PubMed, SPORTDiscus and Google Scholar. After applying a set of inclusion and exclusion criteria, a total of 118 studies were selected for evaluation. Each study was assessed according to the intervention’s ability to lower T c before exercise, attenuate the rise of T c during exercise, extend T c at the end of exercise and improve endurance. Weighted averages of Hedges’ g were calculated for each strategy. Results: PC (g = 1.01) was most effective in lowering T c before exercise, followed by HA (g = 0.72), AF (g = 0.65), and FI (g = 0.11). FI (g = 0.70) was most effective in attenuating the rate of rise of T c , followed by HA (g = 0.35), AF (g = -0.03) and PC (g = -0.46). In extending T c at the end of exercise, AF (g = 1.11) was most influential, followed by HA (g = -0.28), PC (g = -0.29) and FI (g = -0.50). In combination, AF (g = 0.45) was most effective at favorably altering Tc, followed by HA (g = 0.42), PC (g = 0.11) and FI (g = 0.09). AF (1.01) was also found to be most effective in improving endurance, followed by HA (0.19), FI (-0.16) and PC (-0.20). Conclusion: AF was found to be the most effective in terms of a strategy’s ability to favorably alter T c , followed by HA, PC and lastly, FI. Interestingly, a similar ranking was observed in improving endurance, with AF being the most effective, followed by HA, FI, and PC. Knowledge gained from this meta-analysis will be useful in allowing athletes, coaches and sport scientists to make informed decisions when employing heat mitigation strategies during competitions in hot environments.
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Wanted DEAD/H or Alive: Helicases Winding Up in Cancers
Oncotarget. 2016 Jun 7;7(23):34229-39. doi: 10.18632/oncotarget.8748.
Cai W, Xiong Chen Z, Rane G, Satendra Singh S, Choo Z, Wang C, Yuan Y, Zea Tan T, Arfuso F, Yap CT, Pongor LS, Yang H1, Lee MB, Cher Goh B, Sethi G, Benoukraf T, Tergaonkar V, Prem Kumar A.
Abstract
Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as “editing helicases” and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.
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The p75 neurotrophin receptor is an essential mediator of impairments in hippocampal-dependent associative plasticity and memory induced by sleep deprivation
Journal of Neuroscience 13 May 2019, 2876-18; DOI: https://doi.org/10.1523/JNEUROSCI.2876-18.2019
Wong L, Tann JY, Ibáñez CF, Sajikumar S.
Abstract
Sleep deprivation (SD) interferes with hippocampal structural and functional plasticity, formation of long-term memory (LTM) and cognitive function. The molecular mechanisms underlying these effects are incompletely understood. Here, we show that SD impaired synaptic tagging and capture (STC) and behavioral tagging (BT), two major mechanisms of associative learning and memory. Strikingly, mutant male mice lacking the p75 neurotrophin receptor (p75NTR) were resistant to the detrimental effects of SD on hippocampal plasticity at both cellular and behavioral levels. Mechanistically, SD increased p75NTR expression and its interaction with phosphodiesterase (PDE4A5). p75NTR deletion preserved hippocampal structural and functional plasticity by preventing SD-mediated effects on hippocampal cAMP-CREB-BDNF, cAMP-PKA-LIMK1-cofilin and RhoA-ROCK2 pathways. Our study identifies p75NTR as an important mediator of hippocampal structural and functional changes associated with SD, and suggests that targeting p75NTR could be a promising strategy to limit the memory and cognitive deficits that accompany sleep loss.
Altered Brain Structure with Preserved Cortical Motor Activity Following Exertional Hypohydration: A MRI
Journal of Applied Physiology. 2019. doi: 10.1152/japplphysiol.00081.2019.
Tan XR, Low I, Stephenson MC, Kok T, Nolte HW, Soong TW, and Lee JKW.
Abstract
Hypohydration exceeding 2% body mass can impair endurance capacity. It is postulated that the brain could be perturbed by hypohydration, leading to impaired motor performance. We investigated the neural effects of hypohydration using Magnetic Resonance Imaging (MRI). Ten males were dehydrated to ~ -3% body mass by running on a treadmill at 65% VO2max before either drinking to replace 100% (Euhydration; EU) or 0% (Hypohydration; HH) of fluid losses. MRI was performed prior to start of trial (baseline) and after rehydration phase (post) to evaluate brain structure, cerebral perfusion and functional activity. Endurance capacity assessed using a time-to-exhaustion run at 75% VO2max was reduced with hypohydration (EU: 45.2 ± 9.3 min, HH: 38.4 ± 10.7 min; p=0.033). Mean heart rates were comparable between trials (EU: 162 ± 5 bpm, HH: 162 ± 4 bpm, p=0.605) but the rate of rise in rectal temperature was higher in HH trials (EU: 0.06 ± 0.01°C·min-1, HH: 0.07 ± 0.02°C·min-1; p<0.01). In HH trials, a reduction in total brain volume (EU: +0.7 ± 0.6%, HH: -0.7 ± 0.9%) with expansion of ventricles (EU: -2.7 ± 1.6%, HH: +3.7 ± 3.3%) was observed, and vice versa in EU trials. Global and regional cerebral perfusion remained unchanged between conditions. Functional activation in the primary motor cortex (M1) in left hemisphere during a plantar-flexion task was similar between conditions (EU: +0.10 ± 1.30%, HH: -0.11 ± 0.31%; p=0.637). Our findings demonstrated that with exertional hypohydration, brain volumes were altered but the motor-related functional activity was unperturbed.
Redox regulation of cell state and fate.
Redox Biology. 2018 Nov 23; pii: S2213-2317(18)30899-1. doi: 10.1016/j.redox.2018.11.014.
Lee BWL, Ghode P, Ong DST.
Abstract
The failure in effective cancer treatment is thought to be attributed to a subpopulation of tumor cells with stem cell-like properties. These cancer stem cells (CSCs) are intimately linked to tumor initiation, heterogeneity, maintenance, recurrence and metastasis. Increasing evidence supports the view that a tight redox regulation is crucial for CSC proliferation, tumorigenicity, therapy resistance and metastasis in many cancer types. Since the distinct metabolic and epigenetic states of CSCs may influence ROS levels, and hence their malignancy, ROS modulating agents hold promise in their utility as anti-CSC agents that may improve the durability of current cancer treatments. This review will focus on (i) how ROS levels are regulated for CSCs to elicit their hallmark features; (ii) the link between ROS and metabolic plasticity of CSCs; and (iii) how ROS may interface with epigenetics that would enable CSCs to thrive in a stressful tumor microenvironment and survive therapeutic insults.
Abnormal TDP-43 function impairs activity-dependent BDNF secretion, synaptic plasticity, and cognitive behavior through altered Sortilin splicing.
EMBO Journal. 2019 Mar 1;38(5). pii: e100989. doi: 10.15252/embj.2018100989.
Tann JY, Wong LW, Sajikumar S, Ibáñez CF.
Abstract
Aberrant function of the RNA-binding protein TDP-43 has been causally linked to multiple neurodegenerative diseases. Due to its large number of targets, the mechanisms through which TDP-43 malfunction cause disease are unclear. Here, we report that knockdown, aggregation, or disease-associated mutation of TDP-43 all impair intracellular sorting and activity-dependent secretion of the neurotrophin brain-derived neurotrophic factor (BDNF) through altered splicing of the trafficking receptor Sortilin. Adult mice lacking TDP-43 specifically in hippocampal CA1 show memory impairment and synaptic plasticity defects that can be rescued by restoring Sortilin splicing or extracellular BDNF. Human neurons derived from patient iPSCs carrying mutated TDP-43 also show altered Sortilin splicing and reduced levels of activity-dependent BDNF secretion, which can be restored by correcting the mutation. We propose that major disease phenotypes caused by aberrant TDP-43 activity may be explained by the abnormal function of a handful of critical proteins, such as BDNF.
Epigenetics and memory: Emerging role of histone lysine methyltransferase G9a/GLP complex as bidirectional regulator of synaptic plasticity.
Neurobiol Learn Mem. 2019 Mar;159:1-5. doi: 10.1016/j.nlm.2019.01.013.
Pang KKL, Sharma M, Sajikumar S.
Abstract
Various epigenetic modifications, including histone lysine methylation, play an integral role in learning and memory. The importance of the histone lysine methyltransferase complex G9a/GLP and its associated histone H3 lysine K9 dimethylation in memory formation and cognition, has garnered the attention of researchers in the past decade. Recent studies feature G9a/GLP as the ‘bidirectional regulator of synaptic plasticity’, the neural correlate of memory. As the ‘title’ suggests, G9a/GLP participates in the maintenance of both long-term potentiation (LTP) and long-term depression (LTD). This complex is demonstrated to mostly suppress LTP-related plasticity-related products (PRPs). Notably, our recent paper also shows that G9a/GLP facilitates LTD maintenance in intact hippocampal slices – shedding light on the overlooked influence of epigenetics on LTD. Although the exact mechanisms of G9a/GLP activity regulation in cognition remain elusive, pharmacological inhibition of G9a/GLP presents a new avenue of therapeutic intervention in epigenetic dysfunction-related cognitive deficits.
Long-term population spike-timing-dependent plasticity promotes synaptic tagging but not cross-tagging in rat hippocampal area CA1.
Proc Natl Acad Sci U S A. 2019 Mar 19;116(12):5737-5746. doi: 10.1073/pnas.1817643116.
Pang KKL, Sharma M, Krishna-K K, Behnisch T, Sajikumar S.
Abstract
In spike-timing-dependent plasticity (STDP), the direction and degree of synaptic modification are determined by the coherence of pre- and postsynaptic activities within a neuron. However, in the adult rat hippocampus, it remains unclear whether STDP-like mechanisms in a neuronal population induce synaptic potentiation of a long duration. Thus, we asked whether the magnitude and maintenance of synaptic plasticity in a population of CA1 neurons differ as a function of the temporal order and interval between pre- and postsynaptic activities. Modulation of the relative timing of Schaffer collateral fibers (presynaptic component) and CA1 axons (postsynaptic component) stimulations resulted in an asymmetric population STDP (pSTDP). The resulting potentiation in response to 20 pairings at 1 Hz was largest in magnitude and most persistent (4 h) when presynaptic activity coincided with or preceded postsynaptic activity. Interestingly, when postsynaptic activation preceded presynaptic stimulation by 20 ms, an immediate increase in field excitatory postsynaptic potentials was observed, but it eventually transformed into a synaptic depression. Furthermore, pSTDP engaged in selective forms of late-associative activity: It facilitated the maintenance of tetanization-induced early long-term potentiation (LTP) in neighboring synapses but not early long-term depression, reflecting possible mechanistic differences with classical tetanization-induced LTP. The data demonstrate that a pairing of pre- and postsynaptic activities in a neuronal population can greatly reduce the required number of synaptic plasticity-evoking events and induce a potentiation of a degree and duration similar to that with repeated tetanization. Thus, pSTDP determines synaptic efficacy in the hippocampal CA3-CA1 circuit and could bias the CA1 neuronal population toward potentiation in future events.
Generation of mature kupffer cells from human induced pluripotent stem cells.
Biomaterials. 2019 Feb; 192:377-391. doi: 10.1016/j.biomaterials.2018.11.016.
Tasnim F, Xing J, Huang X, Mo S, Wei X, Tan MH, Yu H.
Abstract
Liver macrophages, Kupffer cells (KCs), play a critical role in drug-induced liver injury (DILI) and liver diseases including cholestasis, liver fibrosis and viral hepatitis. Application of KCs in in vitro models of DILI and liver diseases is hindered due to limited source of human KCs. In vivo, KCs originate from MYB-independent macrophage progenitors, which differentiate into liver-specific macrophages in response to hepatic cues in the liver. Here, we recapitulated KCs ontogeny by differentiation of MYB-independent iPSCs to macrophage-precursors and exposing them to hepatic cues to generate iPSC-derived KCs (iKCs). iKCs expressed macrophage markers (CD11/CD14/CD68/CD163/CD32) at 0.3-5 folds of primary adult human KCs (pKCs) and KC-specific CLEC-4F, ID1 and ID3. iKCs phagocytosed and secreted IL-6 and TNFα upon stimulation at levels similar to pKCs but different from non-liver macrophages. Hepatocyte-iKCs co-culture model was more sensitive in detecting hepatotoxicity induced by inflammation-associated drugs, Acetaminophen and Trovafloxacin, and Chlorpromazine-induced cholestasis when compared to hepatocytes alone. Overall, iKCs were mature, liver-specific and functional. Furthermore, donor-matched iKCs and iPSC-hepatocyte co-culture exhibited minimal non-specific background response compared to donor-mismatched counterpart. iKCs offer a mature renewable human cell source for liver-specific macrophages, useful in developing in vitro model to study DILI and liver diseases such as cholestasis.
Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.
Biomaterials. 2019 May;201:16-32. doi: 10.1016/j.biomaterials.2019.01.046.
Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.
Abstract
Interconnected macroporous hydrogel is hydrophilic; it exhibits soft tissue-like mechanical property and aqueous-stable macroporosity for 3D spheroid culture. There is an unmet need to develop cleavable macroporous hydrogel, for the ease of retrieving functional spheroids for further in vitro and in vivo applications. We have developed and comprehensively characterized a hydroxypropyl-cellulose-disulfide sponge by systematically identifying strategies and synthesis schemes to confer cleavability to the sponge under cell-friendly conditions. It preserved the essential advantages of the macroporous hydrogel to support 3D spheroid formation and maintenance of sensitive hepatocytes while allowing rapid cleavage and retrieval of functional spheroids. By culturing HepaRG as spheroids in the cleavable sponge, we have accelerated HepaRG differentiation to 9 days compared to 28 days in 2D culture. Cytochrome P450 basal activity reached significantly higher level, while albumin secretion and fluorescein diacetate staining indicated the same at day 5. The purity of albumin+ hepatocytes reached 92.9% versus 7.1% of CK19+ cholangiocytes at day 9, a much stronger preference for hepatocytes than the 60% albumin+ hepatocytes purity in 2D culture. HepaRG differentiated hepatocytes were retrieved by cleaving the sponge with 10 mM tris-(2-carboxyethyl)-phosphine (TCEP) within 30 min preserving viability, plateability and positive albumin staining of the hepatocyte spheroids. This cleavable macroporous hydrogel sponge will support the rapid development of various 3D spheroid- or organoid-based applications in basic research and drug testing.
Stressing the (Epi)genome: dealing with Reactive Oxygen Species in Cancer
Antioxid Redox Signal. 2018 Nov 1;29(13):1273-1292. doi: 10.1089/ars.2017.7158.
Bhat AV, Hora S, Pal A, Jha S, Taneja R.
Abstract
SIGNIFICANCE:
Growing evidence indicates cross-talk between reactive oxygen species (ROS) and several key epigenetic processes such as DNA methylation, histone modifications, and miRNAs in normal physiology and human pathologies including cancer. This review focuses on how ROS-induced oxidative stress, metabolic intermediates, and epigenetic processes influence each other in various cancers. Recent Advances: ROS alter chromatin structure and metabolism that impact the epigenetic landscape in cancer cells. Several site-specific DNA methylation changes have been identified in different cancers and are discussed in the review. We also discuss the interplay of epigenetic enzymes and miRNAs in influencing malignant transformation in an ROS-dependent manner.
CRITICAL ISSUES:
Loss of ROS-mediated signaling mostly by epigenetic regulation may promote tumorigenesis. In contrast, augmented oxidative stress because of high ROS levels may precipitate epigenetic alterations to effect various phases of carcinogenesis. We address both aspects in the review.
FUTURE DIRECTIONS:
Several drugs targeting ROS are under various stages of clinical development. Recent analysis of human cancers has revealed pervasive deregulation of the epigenetic machinery. Thus, a better understanding of the cross-talk between ROS and epigenetic alterations in cancer could lead to the identification of new drug targets and more effective treatment modalities.
Unravelling the role of Aurora A beyond centrosomes and spindle assembly: implications in muscle differentiation
FASEB Journal. 2019 Jan; 33(1):219-230. doi: 10.1096/fj.201800997.
Dhanasekaran K, Bose A, Rao VJ, Boopathi R, Shankar SR, Rao VK, Swaminathan A, Vasudevan M, Taneja R, Kundu TK.
Abstract
Aurora kinases are critical mitotic serine/threonine kinases and are often implicated in tumorigenesis. Recent studies of the interphase functions for aurora kinase (Aurk)A have considerably expanded our understanding of its role beyond mitosis. To identify the unknown targets of AurkA, we used peptide array-based screening and found E2F4 to be a novel substrate. Phosphorylation of E2F4 by AurkA at Ser75 regulates its DNA binding and subcellular localization. Because E2F4 plays an important role in skeletal muscle differentiation, we attempted to gain insight into E2F4 phosphorylation in this context. We observed that a block in E2F4 phosphorylation retained it better within the nucleus and inhibited muscle differentiation. RNA sequencing analysis revealed a perturbation of the gene network involved in the process of muscle differentiation and mitochondrial biogenesis. Collectively, our findings establish a novel role of AurkA in the process of skeletal muscle differentiation.
Genetics, epigenetics and redox homeostasis in rhabdomyosarcoma: Emerging targets and therapeutics
Redox Biology. 2019 Jan 25. 101124. doi: 10.1016/j.redox.2019.101124.
Srinivasan S, Shankar SR, Wang Y, Taneja R.
Abstract
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma accounting for 5–8% of malignant tumours in children and adolescents. Children with high risk disease have poor prognosis. Anti-RMS therapies include surgery, radiation and combination chemotherapy. While these strategies improved survival rates, they have plateaued since 1990s as drugs that target differentiation and self-renewal of tumours cells have not been identified. Moreover, prevailing treatments are aggressive with drug resistance and metastasis causing failure of several treatment regimes. Significant advances have been made recently in understanding the genetic and epigenetic landscape in RMS. These studies have identified novel diagnostic and prognostic markers and opened new avenues for treatment. An important target identified in high throughput drug screening studies is reactive oxygen species (ROS). Indeed, many drugs in clinical trials for RMS impact tumour progression through ROS. In light of such emerging evidence, we discuss recent findings highlighting key pathways, epigenetic alterations and their impacts on ROS that form the basis of developing novel molecularly targeted therapies in RMS. Such targeted therapies in combination with conventional therapy could reduce adverse side effects in young survivors and lead to a decline in long-term morbidity.
SUMOylation of G9a regulates its function as an activator of myoblast proliferation
Cell Death and Disease. 2019. 10, Article number: 250. doi: 10.1038/s41419-019-1465-9.
Srinivasan S, Shankar SR, Wang Y, Taneja R.
Abstract
The lysine methyltransferase G9a plays a role in many cellular processes. It is a potent repressor of gene expression, a function attributed to its ability to methylate histone and non-histone proteins. Paradoxically, in some instances, G9a can activate gene expression. However, regulators of G9a expression and activity are poorly understood. In this study, we report that endogenous G9a is SUMOylated in proliferating skeletal myoblasts. There are four potential SUMOylation consensus motifs in G9a. Mutation of all four acceptor lysine residues [K79, K152, K256, and K799] inhibits SUMOylation. Interestingly, SUMOylation does not impact G9a-mediated repression of MyoD transcriptional activity or myogenic differentiation. In contrast, SUMO-defective G9a is unable to enhance proliferation of myoblasts. Using complementation experiments, we show that the proliferation defect of primary myoblasts from conditional G9a-deficient mice is rescued by re-expression of wild-type, but not SUMOylation-defective, G9a. Mechanistically, SUMOylation acts as signal for PCAF (P300/CBP-associated factor) recruitment at E2F1-target genes. This results in increased histone H3 lysine 9 acetylation marks at E2F1-target gene promoters that are required for S-phase progression. Our studies provide evidence by which SUMO modification of G9a influences the chromatin environment to impact cell cycle progression.
Bhlhe40 mediates tissue specific control of macrophage proliferation in homeostasis and type 2 immunity
Nature Immunology. 2019, in press. doi:
Jarjour NN, Schwarzkopf EA, Bradstreet TR, Shchukina I, Lin CC, Huang SC, Lai CW, Cook ME, Taneja R, Stappenbeck T, Randolph GJ, Artymov MN, Urban JF, Edelson BT.
Abstract
Abstract
Epigenetic regulation of the PTEN-AKT-RAC1 axis by G9a is critical for tumor growth in alveolar rhabdomyosarcoma
Cancer Research. 2019 in press. doi: 10.1158/0008-5472.CAN-18-2676.
Bhat AV, Palanichamy Kala M, Rao VK, Pignata L, Lim HJ, Suriyamurthy S, Chang KTE, Lee VK, Guccione E, Taneja R.
Abstract
Alveolar Rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer with poor prognosis. As transient and stable modifications to chromatin have emerged as critical mechanisms in oncogenic signaling, efforts to target epigenetic modifiers as a therapeutic strategy have accelerated in recent years. To identify chromatin modifiers that sustain tumor growth, we performed an epigenetic screen and found that inhibition of lysine methyltransferase G9a significantly impacted the viability of ARMS cell lines. Targeting expression or activity of G9a reduced cellular proliferation and motility in vitro and tumor growth in vivo. Transcriptome and chromatin immunoprecipitation-sequencing analysis provided mechanistic evidence that the tumor suppressor PTEN was a direct target gene of G9a. G9a repressed PTEN expression in a methyltransferase activity-dependent manner, resulting in increased AKT and RAC1 activity. Re-expression of constitutively active RAC1 in G9a-deficient tumor cells restored oncogenic phenotypes, demonstrating its critical functions downstream of G9a. Collectively,our study provides evidence for a G9a-dependent epigenetic program that regulates tumor growth and suggests targeting G9a as a therapeutic strategy in ARMS.
Targeting autophagy using natural compounds for cancer prevention and therapy.
Cancer. 2019 Feb 12. doi: 10.1002/cncr.31978. [Epub ahead of print]
Deng S, Shamnmugam MK, Kumar AP, Yap CT, Sethi G, Bishayee A.
Abstract
Autophagy, also known as macroautophagy, is a tightly regulated process involved in the stress responses, such as starvation. It is a vacuolar, lysosomal pathway for the degradation of damaged proteins and organelles in eukaryotic cells. Autophagy also plays a key role in various tissue processes and immune responses and in the regulation of inflammation. Over the past decade, three levels of autophagy regulation have been identified in mammalian cells: 1) signaling, 2) autophagosome formation, and 3) autophagosome maturation and lysosomal degradation. Any deregulation of the autophagy processes can lead to the development of diverse chronic diseases, such as diabetes, obesity, cardiovascular disease, neurodegenerative disease, and malignancies. However, the potential role of autophagy in cancer is rather complex and has been associated with both the induction and the inhibition of neoplasia. Several synthetic autophagy modulators have been identified as promising candidates for cancer therapy. In addition, diverse phytochemicals derived from natural sources, such as curcumin, ursolic acid, resveratrol, thymoquinone, and γ-tocotrienol, also have attracted attention as promising autophagy modulators with minimal side effects. In this review, the authors discuss the importance of autophagy regulators and various natural compounds that induce and/or inhibit autophagy in the prevention and therapy of cancer.
Overriding FUS autoregulation in mice triggers gain-of-toxic dysfunctions in RNA metabolism and autophagy-lysosome axis
eLife. 2019 Feb 12. 8: e40811. doi: 10.7554/eLife.40811.
Ling SC, Dastidar SG, Tokunaga S, Ho WY, Lim K, Illieva H, Parone PA, Tyan S-H, Tse TM, Chang J-C, Platoshyn O, Bui NB, Bui A, Vetto A, Sun S, McAlonis-Downes M, Han JS, Swing D, Kapeli K, Yeo GW, Tessarollo L, Marsala M, Shaw CE, Tucker-Kellogg G, La Spada AR, Lagier-Tourenne C, Da Cruz S, Cleveland DW.
Abstract
Mutations in coding and non-coding regions of FUS cause amyotrophic lateral sclerosis (ALS). The latter mutations may exert toxicity by increasing FUS accumulation. We show here that broad expression within the nervous system of wild-type or either of two ALS-linked mutants of human FUS in mice produces progressive motor phenotypes accompanied by characteristic ALS-like pathology. FUS levels are autoregulated by a mechanism in which human FUS downregulates endogenous FUS at mRNA and protein levels. Increasing wild-type human FUS expression achieved by saturating this autoregulatory mechanism produces a rapidly progressive phenotype and dose-dependent lethality. Transcriptome analysis reveals mis-regulation of genes that are largely not observed upon FUS reduction. Likely mechanisms for FUS neurotoxicity include autophagy inhibition and defective RNA metabolism. Thus, our results reveal that overriding FUS autoregulation will trigger gain-of-function toxicity via altered autophagy-lysosome pathway and RNA metabolism function, highlighting a role for protein and RNA dyshomeostasis in FUS-mediated toxicity.
Understanding Factors that Motivate Research Performance and Career Longevity of STEM Postgraduates
The Asia-Pacific Scholar Medical and Health Professional Education (TAPS). 2019; in press
Chen ZX, Tan M, Herberg J, Samarasekera DD, Yap C.
Abstract
TBA
SIRT2 Inhibition Confers Neuroprotection by Downregulation of FOXO3a and MAPK Signaling Pathways in Ischemic Stroke.
Molecular Neurobiology. 2018 Dec;55(12):9188-9203. doi: 10.1007/s12035-018-1058-0. Epub 2018 Apr 14.
She DT, Wong LJ, Baik SH, Arumugam TV.
Abstract
Sirtuin 2 (SIRT2) is a family member of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases which appears to have detrimental roles in an array of neurological disorders such as Parkinson’s disease (PD) and Huntington’s disease (HD). In light of the recently emerging roles of sirtuins in normal physiology and pathological conditions such as ischemic stroke, we investigated the role of SIRT2 in ischemic stroke-induced neuronal cell death. Primary cortical neurons were subjected to oxygen-glucose deprivation (OGD) under in vitro ischemic conditions, and subsequently tested for the efficacy of SIRT2 inhibitors AK1 and AGK2 in attenuating apoptotic cell death caused by OGD. We have also evaluated the effect of SIRT2 inhibition in C57BL/6 mice subjected to 1 h middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion, which is a model for ischemic reperfusion injury in vivo. Significant reductions in apoptotic cell death were noted in neurons treated with AK1 or AGK2, as evidenced by reduced cleaved caspase-3 and other apoptotic markers such as Bim and Bad. In addition, downregulation of phosphorylated-AKT and FOXO3a proteins of the AKT/FOXO3a pathway, as well as a marked reduction of JNK activity and its downstream target c-Jun, were also observed. When tested in animals subjected to MCAO, the neuroprotective effects of AGK2 in vivo were evidenced by a substantial reduction in ipsilateral infarct area and a significant improvement in neurological outcomes. A similar reduction in the levels of pro-apoptotic proteins in the infarct tissue, as well as downregulation of AKT/FOXO3a and JNK pathway, were also noted. In summary, the current study demonstrated the neuroprotective effects of SIRT2 inhibition in ischemic stroke, and identified the downregulation of AKT/FOXO3a and MAPK pathways as intermediary mechanisms which may contribute to the reduction in apoptotic cell death by SIRT2 inhibition.
Metabolic Remodeling during Liver Regeneration.
Caldez MJ, Van Hul N, Koh HWL, Teo XQ, Fan JJ, Tan PY, Dewhurst MR, Too PG, Talib SZA, Chiang BE, Stünkel W, Yu H, Lee P, Fuhrer T, Choi H, Björklund M, Kaldis P.
Abstract
Liver disease is linked to a decreased capacity of hepatocytes to divide. In addition, cellular metabolism is important for tissue homeostasis and regeneration. Since metabolic changes are a hallmark of liver disease, we investigated the connections between metabolism and cell division. We determined global metabolic changes at different stages of liver regeneration using a combination of integrated transcriptomic and metabolomic analyses with advanced functional redox in vivo imaging. Our data indicate that blocking hepatocyte division during regeneration leads to mitochondrial dysfunction and downregulation of oxidative pathways. This resulted in an increased redox ratio and hyperactivity of alanine transaminase allowing the production of alanine and α-ketoglutarate from pyruvate when mitochondrial functions are impaired. Our data suggests that during liver regeneration, cell division leads to hepatic metabolic remodeling. Moreover, we demonstrate that hepatocytes are equipped with a flexible metabolic machinery able to adapt dynamically to changes during tissue regeneration.
Generation of mature kupffer cells from human induced pluripotent stem cells.
Biomaterials. 2019 Feb;192:377-391. doi: 10.1016/j.biomaterials.2018.11.016. Epub 2018 Nov 16.
Tasnim F, Xing J, Huang X, Mo S, Wei X, Tan MH, Yu H.
Abstract
Liver macrophages, Kupffer cells (KCs), play a critical role in drug-induced liver injury (DILI) and liver diseases including cholestasis, liver fibrosis and viral hepatitis. Application of KCs in in vitro models of DILI and liver diseases is hindered due to limited source of human KCs. In vivo, KCs originate from MYB-independent macrophage progenitors, which differentiate into liver-specific macrophages in response to hepatic cues in the liver. Here, we recapitulated KCs ontogeny by differentiation of MYB-independent iPSCs to macrophage-precursors and exposing them to hepatic cues to generate iPSC-derived KCs (iKCs). iKCs expressed macrophage markers (CD11/CD14/CD68/CD163/CD32) at 0.3-5 folds of primary adult human KCs (pKCs) and KC-specific CLEC-4F, ID1 and ID3. iKCs phagocytosed and secreted IL-6 and TNFα upon stimulation at levels similar to pKCs but different from non-liver macrophages. Hepatocyte-iKCs co-culture model was more sensitive in detecting hepatotoxicity induced by inflammation-associated drugs, Acetaminophen and Trovafloxacin, and Chlorpromazine-induced cholestasis when compared to hepatocytes alone. Overall, iKCs were mature, liver-specific and functional. Furthermore, donor-matched iKCs and iPSC-hepatocyte co-culture exhibited minimal non-specific background response compared to donor-mismatched counterpart. iKCs offer a mature renewable human cell source for liver-specific macrophages, useful in developing in vitro model to study DILI and liver diseases such as cholestasis.
KDM4B-regulated unfolded protein response as a therapeutic vulnerability in PTEN-deficient breast cancer
J Exp Med. 2018 Sep 28. pii: jem.20180439. doi: 10.1084/jem.20180439. [Epub ahead of print]
Wang W, Oguz G, Lee PL, Bao Y, Wang P, Terp MG, Ditzel HJ, Yu Q
Abstract
PTEN deficiency in breast cancer leads to resistance to PI3K-AKT inhibitor treatment despite aberrant activation of this signaling pathway. Here, we report that genetic depletion or small molecule inhibition of KDM4B histone demethylase activates the unfolded protein response (UPR) pathway and results in preferential apoptosis in PTEN-deficient triple-negative breast cancers (TNBCs). Intriguingly, this function of KDM4B on UPR requires its demethylase activity but is independent of its canonical role in histone modification, and acts through its cytoplasmic interaction with eIF2α, a crucial component of UPR signaling, resulting in reduced phosphorylation of this component. Targeting KDM4B in combination with PI3K inhibition induces further activation of UPR, leading to robust synergy in apoptosis. These findings identify KDM4B as a therapeutic vulnerability in PTEN-deficient TNBC that otherwise would be resistant to PI3K inhibition.
Localisation of Formyl-Peptide Receptor 2 in the Rat Central Nervous System and Its Role in Axonal and Dendritic Outgrowth.
Neurochem Res. 2018 Aug;43(8):1587-1598. doi: 10.1007/s11064-018-2573-0. Epub 2018 Jun 13.
Ho CF, Ismail NB, Koh JK, Gunaseelan S, Low YH, Ng YK, Chua JJ, Ong WY.
Abstract
Arachidonic acid and docosahexaenoic acid (DHA) released by the action of phospholipases A2 (PLA2) on membrane phospholipids may be metabolized by lipoxygenases to the anti-inflammatory mediators lipoxin A4 (LXA4) and resolvin D1 (RvD1), and these can bind to a common receptor, formyl-peptide receptor 2 (FPR2). The contribution of this receptor to axonal or dendritic outgrowth is unknown. The present study was carried out to elucidate the distribution of FPR2 in the rat CNS and its role in outgrowth of neuronal processes. FPR2 mRNA expression was greatest in the brainstem, followed by the spinal cord, thalamus/hypothalamus, cerebral neocortex, hippocampus, cerebellum and striatum. The brainstem and spinal cord also contained high levels of FPR2 protein. The cerebral neocortex was moderately immunolabelled for FPR2, with staining mostly present as puncta in the neuropil. Dentate granule neurons and their axons (mossy fibres) in the hippocampus were very densely labelled. The cerebellar cortex was lightly stained, but the deep cerebellar nuclei, inferior olivary nucleus, vestibular nuclei, spinal trigeminal nucleus and dorsal horn of the spinal cord were densely labelled. Electron microscopy of the prefrontal cortex showed FPR2 immunolabel mostly in immature axon terminals or ‘pre-terminals’, that did not form synapses with dendrites. Treatment of primary hippocampal neurons with the FPR2 inhibitors, PBP10 or WRW4, resulted in reduced lengths of axons and dendrites. The CNS distribution of FPR2 suggests important functions in learning and memory, balance and nociception. This might be due to an effect of FPR2 in mediating arachidonic acid/LXA4 or DHA/RvD1-induced axonal or dendritic outgrowth.
Forebrain medial septum sustains experimental neuropathic pain.
Sci Rep. 2018 Aug 8;8(1):11892. doi: 10.1038/s41598-018-30177-3.
Ariffin MZ, Ibrahim KM, Lee AT, Lee RZ, Poon SY, Thong HK, Liu EHC, Low CM, Khanna S.
Abstract
The present study explored the role of the medial septal region (MS) in experimental neuropathic pain. For the first time, we found that the MS sustains nociceptive behaviors in rodent models of neuropathic pain, especially in the chronic constriction injury (CCI) model and the paclitaxel model of chemotherapy-induced neuropathic pain. For example, inactivation of the MS with intraseptal muscimol (2 μg/μl, 0.5 μl), a GABA mimetic, reversed peripheral hypersensitivity (PH) in the CCI model and induced place preference in a conditioned place preference task, a surrogate measure of spontaneous nociception. The effect of intraseptal muscimol on PH was comparable to that seen with microinjection of the local anesthetic, lidocaine, into rostral ventromedial medulla which is implicated in facilitating experimental chronic nociception. Cellular analysis in the CCI model showed that the MS region sustains nociceptive gain with CCI by facilitating basal nociceptive processing and the amplification of stimulus-evoked neural processing. Indeed, consistent with the idea that excitatory transmission through MS facilitates chronic experimental pain, intraseptal microinjection of antagonists acting at AMPA and NMDA glutamate receptors attenuated CCI-induced PH. We propose that the MS is a central monitor of bodily nociception which sustains molecular plasticity triggered by persistent noxious insult.
Type 2 Diabetes Promotes Cell Centrosome Amplification via AKT-ROS-Dependent Signalling of ROCK1 and 14-3-3σ.
Cell Physiol Biochem. 2018;47(1):356-367. doi: 10.1159/000489812. Epub 2018 May 11.
Wang P, Lu YC, Wang J, Wang L, Yu H, Li YF, Kong A, Chan J, Lee S.
Abstract
BACKGROUND/AIMS:
Type 2 diabetes is associated with oxidative stress and DNA damage which can cause centrosome amplification. Thus, the study investigated centrosome amplification in type 2 diabetes and the underlying mechanisms.
METHODS:
Centrosome numbers in human peripheral blood mononuclear blood cells (PBMC) from healthy subjects and patients with type 2 diabetes were compared to access the association between type 2 diabetes and centrosome amplification. Colon cancer cells were used to investigate the molecular mechanisms underlying the centrosome amplification triggered by high glucose, insulin and palmitic acid. Western blot analysis was used to quantify the level of protein and protein phosphorylation. Immunofluorescent staining was performed to detect centrosomes. ROS was quantified using flow cytometry technique. Transcriptpmic profiling was performed using Illumina HiSeqTM500 platform.
RESULTS:
We found that centrosome amplification was increased PBMC from the type 2 diabetic patients, which correlated with the levels of fasting blood glucose and HbA1c. High glucose, insulin and palmitic acid, alone or in combinations, induced ROS production and centrosome amplification. Together, they increased AKT activation as well as the expression, binding and centrosome translation of ROCK1 and 14-3-3σ. Results from further analyses showed that AKT-ROS-dependent upregulations of expression, binding and centrosome translocation of ROCK1 and 14-3-3σ was the molecular pathway underlying the centrosome amplification in vitro triggered by high glucose, insulin and palmitic acid. Moreover, the key in vitro molecular signalling events activated by high glucose, insulin and palmitic acid were verified in PBMC from the patients with type 2 diabetes.
CONCLUSION:
Our results show that type 2 diabetes promotes cell centrosome amplification, and suggest that the diabetic pathophysiological factors-activated AKT-ROS-dependent signalling of ROCK1 and 14-3-3σ is the underlying molecular mechanism.
TGFβ1-mediated suppression of cytochrome P450(CYP) induction responses in rat hepatocyte-fibroblast co-cultures.
Toxicol In Vitro. 2018 Aug;50:47-53. doi: 10.1016/j.tiv.2018.01.015. Epub 2018 Jan 31.
Yu Y, Ananthanarayanan A, Singh NH, Hong X, Sakban RB, Mittal N, Xiaobei L, Robens J, Xia L, McMillian M, Yu H.
Abstract
Co-culture of hepatocyte and fibroblasts has shown distinct advantages in enhancing certain liver specific functions and maintaining hepatic polarity. However, the utility of hepatocyte co-culture models for studies, such as drug-drug interaction studies, has not been completely elucidated. In this study the induction of Cyp1a2, Cyp2b1/2, and Cyp3a2, the three major cytochrome P450 (CYP) isoforms in the rat liver, was evaluated in randomly mixed co-cultures and micropatterned co-cultures. We found that in both co-culture configurations, the drug-induced Cyp1a2, Cyp2b1/2, Cyp3a2 mRNA and activity were suppressed relative to those in monocultured hepatocytes. Further, we observed a significant increase in TGFβ1 production in the co-cultures. Addition of 100 pg/ml TGFβ1 to hepatocyte monocultures resulted in the suppression of Cyp1a2, Cyp2b1/2, and Cyp3a2 induction. These findings implicate TGFβ1 as one of the important factors impairing drug induced CYP induction in co-cultures and suggests that caution needs to be exercised in the use of hepatocyte-fibroblast co-cultures for CYP induction studies.
Cross Talk Between Cellular Redox State and the Antiapoptotic Protein Bcl-2.
Antioxid Redox Signal. 2018 Feb 15. doi: 10.1089/ars.2017.7414.
Pohl SÖ, Agostino M, Dharmarajan A, Pervaiz S.
Abstract
SIGNIFICANCE:B cell lymphoma-2 (Bcl-2) was discovered over three decades ago and is the prototype antiapoptotic member of the Bcl-2 family that comprises proteins with contrasting effects on cell fate. First identified as a consequence of chromosomal translocation (t 14:18) in human lymphoma, subsequent studies have revealed mutations and/or gene copy number alterations as well as posttranslational modifications of Bcl-2 in a variety of human cancers. The canonical function of Bcl-2 is linked to its ability to inhibit mitochondrial membrane permeabilization, thereby regulating apoptosome assembly and activation by blocking the cytosolic translocation of death amplification factors. Of note, the identification of specific domains within the Bcl-2 family of proteins (Bcl-2 homology domains; BH domains) has not only provided a mechanistic insight into the various interactions between the member proteins but has also been the impetus behind the design and development of small molecule inhibitors and BH3 mimetics for clinical use. Recent Advances: Aside from its role in maintaining mitochondrial integrity, recent evidence provides testimony to a novel facet in the biology of Bcl-2 that involves an intricate cross talk with cellular redox state. Bcl-2 overexpression modulates mitochondrial redox metabolism to create a “pro-oxidant” milieu, conducive for cell survival. However, under states of oxidative stress, overexpression of Bcl-2 functions as a redox sink to prevent excessive buildup of reactive oxygen species, thereby inhibiting execution signals. Emerging evidence indicates various redox-dependent transcriptional changes and posttranslational modifications with different functional outcomes.
CRITICAL ISSUES:Understanding the complex interplay between Bcl-2 and the cellular redox milieu from the standpoint of cell fate signaling remains vital for a better understanding of pathological states associated with altered redox metabolism and/or aberrant Bcl-2 expression.
FUTURE DIRECTIONS:Based on its canonical functions, Bcl-2 has emerged as a potential druggable target. Small molecule inhibitors of Bcl-2 and/or other family members with similar function, as well as BH3 mimetics, are showing promise in the clinic. The emerging evidence for the noncanonical activity linked to cellular redox metabolism provides a novel avenue for the design and development of diagnostic and therapeutic strategies against cancers refractory to conventional chemotherapy by the overexpression of this prosurvival protein.
Reactive Oxygen Species and Oncoprotein Signaling-A Dangerous Liaison.
Antioxid Redox Signal. 2018 Jan 9. doi: 10.1089/ars.2017.7441.
Chong SJF, Lai JXH, Eu JQ, Bellot GL, Pervaiz S.
Abstract
SIGNIFICANCE: here is evidence to implicate reactive oxygen species (ROS) in tumorigenesis and its progression. This has been associated with the interplay between ROS and oncoproteins, resulting in enhanced cellular proliferation and survival. Recent Advances: To date, studies have investigated specific contributions of the crosstalk between ROS and signaling networks in cancer initiation and progression. These investigations have challenged the established dogma of ROS as agents of cell death by demonstrating a secondary function that fuels cell proliferation and survival. Studies have thus identified (onco)proteins (Bcl-2, STAT3/5, RAS, Rac1, and Myc) in manipulating ROS level as well as exploiting an altered redox environment to create a milieu conducive for cancer formation and progression.
CRITICAL ISSUES: Despite these advances, drug resistance and its association with an altered redox metabolism continue to pose a challenge at the mechanistic and clinical levels. Therefore, identifying specific signatures, altered protein expressions, and modifications as well as protein-protein interplay/function could not only enhance our understanding of the redox networks during cancer initiation and progression but will also provide novel targets for designing specific therapeutic strategies.
FUTURE DIRECTIONS: Not only a heightened realization is required to unravel various gene/protein networks associated with cancer formation and progression, particularly from the redox standpoint, but there is also a need for developing more sensitive tools for assessing cancer redox metabolism in clinical settings. This review attempts to summarize our current knowledge of the crosstalk between oncoproteins and ROS in promoting cancer cell survival and proliferation and treatment strategies employed against these oncoproteins.
Breast Cancer: A Molecular and Redox Snapshot.
2016 Aug 20;25(6):337-70. doi: 10.1089/ars.2015.6546.
Raman D, Foo CH, Clement MV, Pervaiz S.
Abstract
SIGNIFICANCE: Breast cancer is a unique disease characterized by heterogeneous cell populations causing roadblocks in therapeutic medicine, owing to its complex etiology and primeval understanding of the biology behind its genesis, progression, and sustenance. Globocan statistics indicate over 1.7 million new breast cancer diagnoses in 2012, accounting for 25% of all cancer morbidities.
RECENT ADVANCES: Despite these dismal statistics, the introduction of molecular gene signature platforms, progressive therapeutic approaches in diagnosis, and management of breast cancer has led to more effective treatment strategies and control measures concurrent with an equally reassuring decline in the mortality rate.
CRITICAL ISSUES: However, an enormous body of research in this area is requisite as high mortality associated with metastatic and/or drug refractory tumors continues to present a therapeutic challenge. Despite advances in systemic chemotherapy, the median survival of patients harboring metastatic breast cancers continues to be below 2 years.
FUTURE DIRECTIONS: Hence, a massive effort to scrutinize and evaluate chemotherapeutics on the basis of the molecular classification of these cancers is undertaken with the objective to devise more attractive and feasible approaches to treat breast cancers and improve patients’ quality of life. This review aims to summarize the current understanding of the biology of breast cancer as well as challenges faced in combating breast cancer, with special emphasis on the current battery of treatment strategies. We will also try and gain perspective from recent encounters on novel findings responsible for the progression and metastatic transformation of breast cancer cells in an endeavor to develop more targeted treatment options.
PTEN-L is a novel protein phosphatase for ubiquitin dephosphorylation to inhibit PINK1-Parkin-mediated mitophagy
Cell Res. 2018 Aug;28(8):787-802. doi: 10.1038/s41422-018-0056-0. Epub 2018 Jun 22.
Wang L, Cho YL, Tang Y, Wang J, Park JE, Wu Y, Wang C, Tong Y, Chawla R, Zhang J, Shi Y, Deng S, Lu G, Wu Y, Tan HW, Pawijit P, Lim GG, Chan HY, Zhang J, Fang L, Yu H, Liou YC, Karthik M, Bay BH, Lim KL, Sze SK, Yap CT, Shen HM.
Abstract
Mitophagy is an important type of selective autophagy for specific elimination of damaged mitochondria. PTEN-induced putative kinase protein 1 (PINK1)-catalyzed phosphorylation of ubiquitin (Ub) plays a critical role in the onset of PINK1-Parkin-mediated mitophagy. Phosphatase and tensin homolog (PTEN)-long (PTEN-L) is a newly identified isoform of PTEN, with addition of 173 amino acids to its N-terminus. Here we report that PTEN-L is a novel negative regulator of mitophagy via its protein phosphatase activity against phosphorylated ubiquitin. We found that PTEN-L localizes at the outer mitochondrial membrane (OMM) and overexpression of PTEN-L inhibits, whereas deletion of PTEN-L promotes, mitophagy induced by various mitochondria-damaging agents. Mechanistically, PTEN-L is capable of effectively preventing Parkin mitochondrial translocation, reducing Parkin phosphorylation, maintaining its closed inactive conformation, and inhibiting its E3 ligase activity. More importantly, PTEN-L reduces the level of phosphorylated ubiquitin (pSer65-Ub) in vivo, and in vitro phosphatase assay confirms that PTEN-L dephosphorylates pSer65-Ub via its protein phosphatase activity, independently of its lipid phosphatase function. Taken together, our findings demonstrate a novel function of PTEN-L as a protein phosphatase for ubiquitin, which counteracts PINK1-mediated ubiquitin phosphorylation leading to blockage of the feedforward mechanisms in mitophagy induction and eventual suppression of mitophagy. Thus, understanding this novel function of PTEN-L provides a key missing piece in the molecular puzzle controlling mitophagy, a critical process in many important human diseases including neurodegenerative disorders such as Parkinson’s disease.
G9a/GLP Complex Acts as a Bidirectional Switch to Regulate Metabotropic Glutamate Receptor-Dependent Plasticity in Hippocampal CA1 Pyramidal Neurons.
Cereb Cortex. 2018 Jul 6. doi: 10.1093/cercor/bhy161.
Sharma M, Sajikumar S.
Abstract
Metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) is conventionally considered to be solely dependent on local protein synthesis. Given the impact of epigenetics on memory, the intriguing question is whether epigenetic regulation influences mGluR-LTD as well. G9a/GLP histone lysine methyltransferase complex is crucial for brain development and goal-directed learning as well as for drug-addiction. In this study, we analyzed whether the epigenetic regulation by G9a/GLP complex affects mGluR-LTD in CA1 hippocampal pyramidal neurons of 5-7 weeks old male Wistar rats. In hippocampal slices with intact CA1 dendritic regions, inhibition of G9a/GLP activity abolished mGluR-LTD. The inhibition of this complex upregulated the expression of plasticity proteins like PKMζ, which mediated the prevention of mGluR-LTD expression by regulating the NSF-GluA2-mediated trafficking of AMPA receptors towards the postsynaptic site. G9a/GLP inhibition during the induction of mGluR-LTD also downregulated the protein levels of phosphorylated-GluA2 and Arc. Interestingly, G9a/GLP inhibition could not impede the mGluR-LTD when the cell-body was severed. Our study highlights the role of G9a/GLP complex in intact neuronal network as a bidirectional switch; when turned on, it facilitates the expression of mGluR-LTD, and when turned off, it promotes the expression of long-term potentiation.
Regulation of feeding by somatostatin neurons in the tuberal nucleus.
Science. 2018 Jul 6;361(6397):76-81. doi: 10.1126/science.aar4983.
Luo SX, Huang J, Li Q, Mohammad H, Lee CY, Krishna K, Kok AM, Tan YL, Lim JY, Li H, Yeow LY, Sun J, He M, Grandjean J, Sajikumar S, Han W, Fu Y.
Abstract
The tuberal nucleus (TN) is a surprisingly understudied brain region. We found that somatostatin (SST) neurons in the TN, which is known to exhibit pathological or cytological changes in human neurodegenerative diseases, play a crucial role in regulating feeding in mice. GABAergic tuberal SST (TNSST) neurons were activated by hunger and by the hunger hormone, ghrelin. Activation of TNSST neurons promoted feeding, whereas inhibition reduced it via projections to the paraventricular nucleus and bed nucleus of the stria terminalis. Ablation of TNSST neurons reduced body weight gain and food intake. These findings reveal a previously unknown mechanism of feeding regulation that operates through orexigenic TNSST neurons, providing a new perspective for understanding appetite changes.
Enriched Expression of Neutral Sphingomyelinase 2 in the Striatum is Essential for Regulation of Lipid Raft Content and Motor Coordination.
Molecular Neurobiology. 2018 Jul;55(7):5741-5756. doi: 10.1007/s12035-017-0784-z. Epub 2017 Oct 17.
Tan LH, Tan AJ, Ng YY, Chua JJ, Chew WS, Muralidharan S, Torta F, Dutta B, Sze SK, Herr DR, Ong WY.
Abstract
Sphingomyelinases are a family of enzymes that hydrolyze sphingomyelin to generate phosphocholine and ceramide. The brain distribution and function of neutral sphingomyelinase 2 (nSMase2) were elucidated in this study. nSMase2 mRNA expression was greatest in the striatum, followed by the prefrontal cortex, hippocampus, cerebellum, thalamus, brainstem, and olfactory bulb. The striatum had the highest level of nSMase2 protein expression, followed by the prefrontal cortex, thalamus, hippocampus, brainstem, and cerebellum. Dense immunolabeling was observed in the striatum, including the caudate-putamen, while moderately dense staining was found in the olfactory bulb and cerebral neocortex. Electron microscopy of the caudate-putamen showed nSMase2 immunoreaction product was present in small diameter dendrites or dendritic spines, that formed asymmetrical synapses with unlabeled axon terminals containing small round vesicles; and characteristics of glutamatergic axons. Lipidomic analysis of the striatum showed increase in long chain sphingomyelins, SM36:1 and SM38:1 after inhibition of nSMase activity. Quantitative proteomic analysis of striatal lipid raft fraction showed many proteins were downregulated by more than 2-fold after inhibition or antisense knockdown of nSMase; consistent with the notion that nSMase2 activity is important for aggregation or clustering of proteins in lipid rafts. Inhibition or antisense knockdown of nSMase2 in the caudate-putamen resulted in motor deficits in the rotarod and narrow beam tests; as well as decreased acoustic startle and improved prepulse inhibition of the startle reflex. Together, results indicate an important function of nSMase2 in the striatum.
Hallmarks of Brain Aging: Adaptive and Pathological Modification by Metabolic States.
Cell Metabolism. 2018 Jun 5;27(6):1176-1199. doi: 10.1016/j.cmet.2018.05.011.
Mattson MP, Arumugam TV.
Abstract
During aging, the cellular milieu of the brain exhibits tell-tale signs of compromised bioenergetics, impaired adaptive neuroplasticity and resilience, aberrant neuronal network activity, dysregulation of neuronal Ca2+ homeostasis, the accrual of oxidatively modified molecules and organelles, and inflammation. These alterations render the aging brain vulnerable to Alzheimer’s and Parkinson’s diseases and stroke. Emerging findings are revealing mechanisms by which sedentary overindulgent lifestyles accelerate brain aging, whereas lifestyles that include intermittent bioenergetic challenges (exercise, fasting, and intellectual challenges) foster healthy brain aging. Here we provide an overview of the cellular and molecular biology of brain aging, how those processes interface with disease-specific neurodegenerative pathways, and how metabolic states influence brain health.
A 3D Microfluidic Model to Recapitulate Cancer Cell Migration and Invasion.
Bioengineering. 2018 Apr 8;5(2). pii: E29. doi: 10.3390/bioengineering5020029.
Toh YC, Raja A, Yu H, van Noort D.
Abstract
We have developed a microfluidic-based culture chip to simulate cancer cell migration and invasion across the basement membrane. In this microfluidic chip, a 3D microenvironment is engineered to culture metastatic breast cancer cells (MX1) in a 3D tumor model. A chemo-attractant was incorporated to stimulate motility across the membrane. We validated the usefulness of the chip by tracking the motilities of the cancer cells in the system, showing them to be migrating or invading (akin to metastasis). It is shown that our system can monitor cell migration in real time, as compare to Boyden chambers, for example. Thus, the chip will be of interest to the drug-screening community as it can potentially be used to monitor the behavior of cancer cell motility, and, therefore, metastasis, in the presence of anti-cancer drugs.
Epigenetic regulation of inflammation in stroke.
Ng GY, Lim YA, Sobey CG, Dheen T, Fann DY, Arumugam TV.
Abstract
Despite extensive research, treatments for clinical stroke are still limited only to the administration of tissue plasminogen activator and the recent introduction of mechanical thrombectomy, which can be used in only a limited proportion of patients due to time constraints. A plethora of inflammatory events occur during stroke, arising in part due to the body’s immune response to brain injury. Neuroinflammation contributes significantly to neuronal cell death and the development of functional impairment and death in stroke patients. Therefore, elucidating the molecular and cellular mechanisms underlying inflammatory damage following stroke injury will be essential for the development of useful therapies. Research findings increasingly point to the likelihood that epigenetic mechanisms play a role in the pathophysiology of stroke. Epigenetics involves the differential regulation of gene expression, including those involved in brain inflammation and remodelling after stroke. Hence, it is conceivable that epigenetic mechanisms may contribute to differential interindividual vulnerability and injury responses to cerebral ischaemia. In this review, we summarize recent findings on the emerging role of epigenetics in the regulation of neuroinflammation in stroke. We also discuss potential epigenetic targets that may be assessed for the development of stroke therapies.
Triple negative breast cancer in Asia: An insider’s view
Wang C, Kar S, Lai X, Cai W, Arfuso F, Sethi G, Lobie PE, Goh BC, Lim LHK, Hartman M, Chan CW, Lee SC, Tan SH, Kumar AP.
Abstract
While tremendous improvement has been made for the treatment of breast cancers, the treatment of triple negative breast cancer (TNBC) still remains a challenge due to its aggressive characteristics and limited treatment options. Most of the studies on TNBC were conducted in Western population and TNBC is reported to be more frequent in the African women. This review encapsulates the studies conducted on TNBC patients in Asian population and elucidates the similarities and differences between these two regions. The current treatment of TNBC includes surgery, radiotherapy and chemotherapy. In addition to the current chemotherapies, which mainly include cytotoxic agents, such as taxanes and anthracyclines, many clinical trials are investigating the potential use of other chemotherapy drugs, targeted therapeutics and combinational therapies to treat TNBC. Moreover, this review also integrates the studies involving novel markers, which will help us to dissect the pathologic process of TNBC and in turn facilitate the development of better treatment strategies to combat TNBC.