Publications - 2020
Bacterial-induced cell fusion is a danger signal triggering cGAS–STING pathway via micronuclei formation |
| Joanne Wei Kay Ku, Yahua Chen, Bryan Jian Wei Lim, Stephan Gasser, Karen Carmelina Crasta, and Yunn-Hwen Gan |
| PNAS July 7, 2020 117 (27) 15923-15934. DOI: 10.1073/pnas.2006908117 |
| 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. |
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 |
| Mutation Research/Genetic Toxicology and Environmental Mutagenesis. Volumes 861–862, January–February 2021, 503303. DOI: 10.1016/j.mrgentox.2020.503303 |
| 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 |
| Volodymyr Vinnikov, Manoor Prakash Hande, Ruth Wilkins, Andrzej Wojcik, Eduardo Zubizarreta and Oleg Belyakov |
| Journal of Personalized Medicine, Volume 10, Issue 4. DOI: 10.3390/jpm10040285 |
| 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 |
| Deepika Kandilya, Sukanya Shyamasundar, Dhiraj Kumar Singh, Avijit Banik, Manoor Prakash Hande, Walter Stünkel, Yap Seng Chong & S. Thameem Dheen |
| Scientific Reports volume 10, Article number: 15676 (2020). DOI: 10.1038/s41598-020-72485-7 |
| 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. |
Hydrogel-based colorectal cancer organoid co-culture models |
| Xiaobei Luo, Eliza Li Shan Fong, Chaojun Zhua, Quy Xiao Xuan Lin, Man Xiong, Aimin Li, Tingting Li, Touati Benoukr, Hanry Yu, Side Liu |
| Acta Biomaterialia, (2021), Available online 31 December 2020. doi: 10.1016/j.actbio.2020.12.037. |
| 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. |
ER-luminal [Ca 2+] regulation of InsP 3 receptor gating mediated by an ER-luminal peripheral Ca 2+-binding protein |
| 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 |
| Elife. 2020 May 18;9:e53531. doi: 10.7554/eLife.53531. |
| 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 |
| Neelima Gupta, Shweta Jadhav, Kai-Leng Tan, Genevieve Saw, Karthik Babu Mallilankaraman, S Thameem Dheen |
| Front Cell Neurosci. 2020 May 21;14:132. doi: 10.3389/fncel.2020.00132. eCollection 2020. |
| 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. |
Oxygen Glucose Deprivation Induced Prosurvival Autophagy Is Insufficient to Rescue Endothelial Function |
| Venkateswaran Natarajan, Tania Mah, Chen Peishi, Shu Yi Tan, Ritu Chawla, Thiruma Valavan Arumugam, Adaikalavan Ramasamy, Karthik Mallilankaraman |
| Front Physiol. 2020 Sep 16;11:533683. doi: 10.3389/fphys.2020.533683. eCollection 2020. |
| 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) |
| Karthik Mallilankaraman et al |
| Autophagy. 2021 Jan;17(1):1-382. doi: 10.1080/15548627.2020.1797280. Epub 2021 Feb 8. |
| Abstract |
| no astract available |
Managing Heat Stress in the Workplace |
| 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 |
| Workplace Safety and Health Guidelines. doi: 10.13140/RG.2.2.22210.81604. |
| Abstract |
| no astract available |
Inactive variants of death receptor p75 NTR reduce Alzheimer's neuropathology by interfering with APP internalization |
| Chenju Yi, Ket Yin Goh, Lik-Wei Wong, Ajeena Ramanujan, Kazuhiro Tanaka, Sreedharan Sajikumar, Carlos F Ibáñez |
| EMBO J. 2021 Jan 15;40(2):e104450. doi: 10.15252/embj.2020104450. |
| 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. |
A 12-week aerobic exercise intervention results in improved metabolic function and lower adipose tissue and ectopic fat in high-fat diet fed rats |
| 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 |
| Biosci Rep. 2021 Jan 29;41(1):BSR20201707. doi: 10.1042/BSR20201707. |
| 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. |
Identification of CD137-Expressing B Cells in Multiple Sclerosis Which Secrete IL-6 Upon Engagement by CD137 Ligand |
| Hiu Yi Wong, Ankshita Prasad, Shu Uin Gan, John Jia En Chua, Herbert Schwarz |
| Front Immunol. 2020 Nov 6;11:571964. doi: 10.3389/fimmu.2020.571964. eCollection 2020. |
| 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 |
| Binbin Wang, Gregory Lucien Bellot, Kartini Iskandar, Tsung Wen Chong, Fera Yiqian Goh, June Jingyi Tai, Herbert Schwarz, Siew Cheng Wong, Shazib Pervaiz |
| Sci Rep. 2020 Nov 2;10(1):18837. doi: 10.1038/s41598-020-74578-9. |
| 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 |
| David Y Fann, Emily Pauline Nickles, Luting Poh, Vismitha Rajeev, Sharmelee Selvaraji, Herbert Schwarz, Thiruma V Arumugam |
| Neuromolecular Med. 2020 Dec;22(4):474-483. doi: 10.1007/s12017-020-08623-1. |
| 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 |
| Qun Zeng, Herbert Schwarz |
| Oncoimmunology. 2020 Jun 17;9(1):1781334. doi: 10.1080/2162402X.2020.1781334. |
| 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 |
| Hiu Yi Wong, Herbert Schwarz |
| J Autoimmun. 2020 Aug;112:102499. doi: 10.1016/j.jaut.2020.102499. |
| 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 |
| 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 |
| Cell Death Differ. 2020 Nov 12. doi: 10.1038/s41418-020-00664-0. |
| 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. |
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 |
| Proc Natl Acad Sci U S A. 2020 Nov 17;117(46):29101-29112. doi: 10.1073/pnas.2007806117. Epub 2020 Oct 30. |
| 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 |
| Acta Neuropathologica Communications volume 8, Article number: 155 (2020) . doi: 10.1186/s40478-020-01030-4. |
| 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 |
| 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 |
| Diabetes Metab Syndr Obes. 2020 Nov 4;13:4157-4167. doi: 10.2147/DMSO.S280350. eCollection 2020. |
| 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. |
| 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 |
| Int J Environ Res Public Health. 2020 Nov 3;17(21):8100. doi: 10.3390/ijerph17218100. |
| Abstract |
Efficacy of Ingesting an Oral Rehydration Solution after Exercise on Fluid Balance and Endurance Performance |
| Priscilla Weiping Fan, Stephen F Burns, Jason Kai Wei Lee |
| Nutrients. 2020 Dec 15;12(12):3826. doi: 10.3390/nu12123826. |
| 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 |
| 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 |
| Nucleic Acids Research, 48(22): 12727–12745. doi:10.1093/nar/gkaa1110. |
| 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 |
| Binbin Wang, Gregory Lucien Bellot, Kartini Iskandar, Tsung Wen Chong, Fera Yiqian Goh, June Jingyi Tai, Herbert Schwarz, Siew Cheng Wong, Shazib Pervaiz |
| Scientific Reports. 2020 Nov 2;10(1):18837. doi: 10.1038/s41598-020-74578-9. |
| 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 |
| 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 |
| Theranostics. 2020 Aug 13;10(22):10274-10289. doi: 10.7150/thno.47001. eCollection 2020. |
| 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 |
| Clarissa Esmeralda Halim, Shuo Deng, Mei Shan Ong, and Celestial T. Yap |
| Biomedicines. 2020 Sep; 8(9): 316. doi: 10.3390/biomedicines8090316. |
| 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 |
| Yi HuiYee, Stephen Jun Fei Chong, Li RenKong, Boon Cher Goh, ShazibPervaiz |
| Redox Biology. 101834. doi: 10.1016/j.redox.2020.101834. |
| 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. |
A Digital CRISPR-based Method for the Rapid Detection and Absolute Quantification of Viral Nucleic Acids. |
| Xiaolin Wu, Cheryl Chan, Yie Hou Lee, Stacy L. Springs, Timothy K. Lu, Hanry Yu |
| MedRxiv. doi: 10.1101/2020.11.03.20223602. |
| 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 |
| 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 |
| eLife 2020;9:e57683 doi: 10.7554/eLife.57683. |
| 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 |
| Cenk Celik, Alfredo Franco-Obregón, Eng Hin Lee, James Hp Hui, Zheng Yang |
| Acta Biomaterilia. 2020 Oct 29;S1742-7061(20)30637-1. doi: 10.1016/j.actbio.2020.10.039. |
| 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 |
| Nandini Karthik, Reshma Taneja |
| Epigenetics. 2020 Aug 2;1-20. doi: 10.1080/15592294.2020.1795606. |
| 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 |
| Yongqiang Luo, Ramya Viswanathan, Manoor Prakash Hande, Amos Hong Pheng Loh and Lih Feng Cheow |
| Science Advances 21 Aug 2020: Vol. 6, no. 34, eabb7944. DOI: 10.1126/sciadv.abb7944 |
| 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 |
| Journal of Environment and Safety / Volume 11 (2020) Issue 2 / Pages 7-10. DOI: 10.11162/daikankyo.E19PROCP15 |
| 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 |
| Sharifah B Alhadad, Ivan C C Low, Jason K W Lee |
| J Sci Med Sport. 2020 Jul 15;S1440-2440(20)30685-X. doi: 10.1016/j.jsams.2020.07.002. |
| 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 |
| Sneha Rajiv Jain, Yuan Sui, Cheng Han Ng, Zhi Xiong Chen, Lay Hoon Goh, Shefaly Shorey |
| PLoS One. 2020 Aug 17;15(8):e0237647. doi: 10.1371/journal.pone.0237647. eCollection 2020. |
| 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 |
| 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 |
| Cancer Sci. 2020 Aug 10. doi: 10.1111/cas.14610. |
| 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 |
| 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 |
| Small. 2020 Aug 12;e2003656. doi: 10.1002/smll.202003656. |
| 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 |
| Dorothy H J Cheong, Daniel W S Tan, Fred W S Wong, Thai Tran |
| Pharmacol Res. 2020 Aug;158:104901. doi: 10.1016/j.phrs.2020.104901. |
| 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. |
MicroRNAs in chronic airway diseases: Clinical correlation and translational applications |
| Bryce W Q Tan, Wei Liang Sim, Jit Kong Cheong, Win Sen Kuan, Thai Tran, Hui Fang Lim |
| Pharmacol Res. 2020 Jun 23;160:105045. doi: 10.1016/j.phrs.2020.105045. |
| 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 |
| 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 |
| Biomaterials. 2020 May;240:119855. doi: 10.1016/j.biomaterials.2020.119855. |
| 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 |
| Kapish Gupta, Inn Chuan Ng, Gowri Manohari Balachander, Binh P Nguyen, Lisa Tucker-Kellogg, Boon Chuan Low, Hanry Yu |
| Biomaterials. 2020 Aug 11;259:120283. doi: 10.1016/j.biomaterials.2020.120283. |
| 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 |
| 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 |
| Temperature. 2020. doi: 10.1080/23328940.2020.1790971. |
| 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 |
| Haili Tian, Sujuan Liu, Jun Ren, Jason Kai Wei Lee, Ru Wang, Peijie Chen |
| Front Physiol. 2020 Aug 11;11:949. doi: 10.3389/fphys.2020.00949. eCollection 2020. |
| 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 |
| Deepika Raman, Stephen J.F. Chong, Kartini Iskandar, Jayshree L. Hirpara, and Shazib Pervaiz |
| Redox Biol. 2020 Jul; 34: 101587. doi: 10.1016/j.redox.2020.101587 |
| 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 |
| Shazib Pervaiz, Gregory L Bellot, Antoinette Lemoin, Catherine Brenner |
| Int Rev Cell Mol Biol. 2020;352:189-214. doi: 10.1016/bs.ircmb.2020.03.002. |
| 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 |
| Stephen Jun Fei Chong, Saverio Marchi, Giulia Petroni, Guido Kroemer, Lorenzo Galluzzi, Shazib Pervaiz |
| Trends Cell Biol. 2020 Jul;30(7):537-555. doi: 10.1016/j.tcb.2020.03.004. |
| 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 |
| Natalie Yan Li Ngoi, Clarice Choong, Joanne Lee, Gregory Bellot, Andrea Li Ann Wong, Boon Cher Goh, Shazib Pervaiz |
| Cancers (Basel). 2020 Mar 2;12(3):574. doi: 10.3390/cancers12030574. |
| 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 |
| 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 |
| Advanced Biosystems. doi: 10.1002/adbi.202000146 |
| 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 |
| 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 |
| Biomicrofluidics 14, 034108. doi: 10.1063/5.0004286 |
| 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 |
| Analytical Chemistry. 2020 Jun 2;92(11):7915-7923. doi: 10.1021/acs.analchem.0c01312. Epub 2020 May 19. |
| 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 |
| 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 |
| Nature Materials. 2020 Apr 27. doi: 10.1038/s41563-020-0662-3. Online ahead of print. |
| 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 |
| 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 |
| Nutrients. 2020 Jun 2;12(6):E1639. doi: 10.3390/nu12061639. |
| 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 |
| T. Kjellstrom, E. Oppermann, J. K. W. Lee |
| Handbook of Socioeconomic Determinants of Occupational Health pp 1-19 |
| 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 |
| Environmental Research. 2020 Apr 15;186:109532. doi: 10.1016/j.envres.2020.109532. Online ahead of print. |
| 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 |
| European Journal of Applied Physiology. 2020 May;120(5):1143-1154. doi: 10.1007/s00421-020-04353-1. Epub 2020 Mar 30. |
| 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 |
| 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 |
| Nature Communications. 2020 Jan 23;11(1):444. doi: 10.1038/s41467-020-14311-2. |
| 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 |
| Lik-Wei Wong, Yee Song Chong, Win Lee Edwin Wong, Sreedharan Sajikumar |
| Cereb Cortex. 2020 Jun 1;30(7):4169-4182. doi: 10.1093/cercor/bhaa041. |
| 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 |
| Winanto, Zi Jian Khong, Boon-Seng Soh, Yong Fan, Shi-Yan Ng |
| Cell Death Disease. 2020 Mar 13;11(3):182. doi: 10.1038/s41419-020-2383-6. |
| 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 |
| 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 |
| Experimental Physiology. 2020 Apr;105(4):622-631. doi: 10.1113/EP088351. Epub 2020 Feb 17. |
| 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 |
| Jorming Goh, Peter Hofmann, Ning Hong Aw, Poh Ling Tan, Gerhard Tschakert, Alexander Mueller, Siew Cheng Wong, Frankie Tan & Linda Seo Hwee Gan |
| Translational Medicine Communications volume 5, Article number: 4 (2020) |
| 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 |
| Patrick B Ampomah, Lina H K Lim |
| Apoptosis. 2020 Feb;25(1-2):1-11.doi: 10.1007/s10495-019-01575-3. |
| 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. |
Group III metabotropic glutamate receptors gate long-term potentiation and synaptic tagging/capture in rat hippocampal area CA2 |
| Ananya Dasgupta, Yu Jia Lim, Krishna Kumar, Nimmi Baby, Ka Lam Karen Pang, Amrita Benoy, Thomas Behnisch, Sreedharan Sajikumar. |
| eLife. doi: 10.7554/eLife.55344 . |
| 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. |
CD137 ligand interacts with CD32a to trigger reverse CD137 ligand signaling Zeng Q, Soe YM, Lim Y, Sobota RM, Schwarz H |
| Zeng Q, Soe YM, Lim Y, Sobota RM, Schwarz H |
| Cell Mol Immunol. 2020 Feb 19. doi: 10.1038/s41423-020-0370-6 |
| Abstract |
| abstract no available |
The relevance of soluble CD137 in the regulation of immune responses and for immunotherapeutic intervention |
| Luu K, Shao Z, Schwarz H |
| J Leukoc Biol. 2020 Feb 13. doi: 10.1002/JLB.2MR1119-224R |
| 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 |
| erma NK, Tran T and Kelleher D |
| Frontiers in Immunology. 2020 Mar 13. doi: 10.3389/fimmu.2020.00441 |
| 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 |
| Wong AH, Tran T |
| Front Cell Dev Biol. 2020 Feb 7;8:64. doi: 10.3389/fcell.2020.00064. eCollection 2020. |
| 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 |
| Srivastava RK, Moliner A, Lee E-S, Nickles E, Sim E, Liu C, Schwarz H and Ibáñez CF |
| Journal of Biological Chemistry. 2020 Feb 14;295, 2034-2042. doi: 10.1074/jbc.AC119.011795. |
| 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. |
Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective |
| Ong MS, Deng S, Halim CE, Cai W, Tan TZ, Huang RY, Sethi G, Hooi SC, Kumar AP, Yap CT. |
| Cancers (Basel). 2020 Jan 18;12(1). pii: E238. doi: 10.3390/cancers12010238. |
| 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 |
| 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. |
| Nature Cell Biology. 2020 Feb;22(2):175-186. doi: 10.1038/s41556-019-0453-8. Epub 2020 Jan 13. |
| 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 |
| Wong L-W, Chong YS, Wong WLE, Sajikumar S |
| Cerebral Cortex. 2020 Mar 16. bhaa041. doi: 10.1093/cercor/bhaa041 |
| 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. |
Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective |
| Ong MS, Deng S, Halim CE, Cai W, Tan TZ, Huang RY-J, Sethi G, Hooi SC,*, Kumar AP,* and Yap CT* |
| Cancers. 2020 Jan; 12(1): 238. doi: 10.3390/cancers12010238. |
| 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 |
| 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 |
| Nature Cell Biology. 2020 Jan. doi: 10.1038/s41556-019-0453-8. |
| 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. |