Publications - 2019

Increased double strand breaks in diabetic β-cells with a p21 response that limits apoptosis

Vanessa S. Y. Tay, Surabhi Devaraj, Tracy Koh, Guo Ke, Karen C. Crasta & Yusuf Ali

Scientific Reports volume 9, Article number: 19341 (2019). DOI: 10.1038/s41598-019-54554-8.

Abstract

DNA damage and DNA damage response (DDR) pathways in β-cells have received little attention especially in the context of type-2 diabetes. We postulate that p21 plays a key role in DDR by preventing apoptosis, associated through its overexpression triggered by DNA stand breaks (DSBs). Our results show that β-cells from chronic diabetic mice had a greater extent of DSBs as compared to their non-diabetic counterparts. Comet assays and nuclear presence of γH2AX and 53bp1 revealed increased DNA DSBs in 16 weeks old (wo) db/db β-cells as compared to age matched non-diabetic β-cells. Our study of gene expression changes in MIN6 cell line with doxorubicin (Dox) induced DNA damage, showed that the DDR was similar to primary β-cells from diabetic mice. There was significant overexpression of DDR genes, gadd45a and p21 after a 24-hr treatment. Western blot analysis revealed increased cleaved caspase3 over time, suggesting higher frequency of apoptosis due to Dox-induced DNA strand breaks. Inhibition of p21 by pharmacological inhibitor UC2288 under DNA damage conditions (both in Dox-induced MIN6 cells and older db/db islets) significantly increased the incidence of β-cell apoptosis. Our studies confirmed that while DNA damage, specifically DSBs, induced p21 overexpression in β-cells and triggered the p53/p21 cellular response, p21 inhibition exacerbated the frequency of apoptosis.

Exosomes as emerging pro-tumorigenic mediators of the senescence-associated secretory phenotype

Rekha Jakhar, Karen Crasta

Int J Mol Sci. 2019 May 24;20(10):2547. DOI: 10.3390/ijms20102547.

Abstract

Communication between cells is quintessential for biological function and cellular homeostasis. Membrane-bound extracellular vesicles known as exosomes play pivotal roles in mediating intercellular communication in tumor microenvironments. These vesicles and exosomes carry and transfer biomolecules such as proteins, lipids and nucleic acids. Here we focus on exosomes secreted from senescent cells. Cellular senescence can alter the microenvironment and influence neighbouring cells via the senescence-associated secretory phenotype (SASP), which consists of factors such as cytokines, chemokines, matrix proteases and growth factors. This review focuses on exosomes as emerging SASP components that can confer pro-tumorigenic effects in pre-malignant recipient cells. This is in addition to their role in carrying SASP factors. Transfer of such exosomal components may potentially lead to cell proliferation, inflammation and chromosomal instability, and consequently cancer initiation. Senescent cells are known to gather in various tissues with age; eliminating senescent cells or blocking the detrimental effects of the SASP has been shown to alleviate multiple age-related phenotypes. Hence, we speculate that a better understanding of the role of exosomes released from senescent cells in the context of cancer biology may have implications for elucidating mechanisms by which aging promotes cancer and other age-related diseases, and how therapeutic resistance is exacerbated with age.

Dynamic contrast-enhanced MRI of brown and beige adipose tissues

Jadegoud Yaligar, Sanjay Kumar Verma, Venkatesh Gopalan, Rengaraj Anantharaj, Giang Thi Thu Le, Kavita Kaur, Karthik Mallilankaraman, Melvin Khee-Shing Leow, S Sendhil Velan

Magn Reson Med. 2020 Jul;84(1):384-395. doi: 10.1002/mrm.28118. Epub 2019 Dec 4.

Abstract

Purpose
The vascular blood flow in brown adipose tissue (BAT) is important for handling triglyceride clearance, increased blood flow and oxygenation. We used dynamic contrast-enhanced (DCE)-MRI and fat fraction (FF) imaging for investigating vascular perfusion kinetics in brown and beige adipose tissues with cold exposure or treatment with β3-adrenergic agonist.
Methods
FF imaging and DCE-MRI using gadolinium-diethylenetriaminepentaacetic acid were performed in interscapular BAT (iBAT) and beige tissues using male Wister rats (n = 38). Imaging was performed at thermoneutral condition and with either cold exposure, treatment with pharmacological agent CL-316,243, or saline. DCE-MRI and FF data were co-registered to enhance the understanding of metabolic activity.
Results
Uptake of contrast agent in activated iBAT and beige tissues were significantly (P < .05) higher than nonactivated iBAT. The Ktrans and kep increased significantly in iBAT and beige tissues after treatment with either cold exposure or β3-adrenergic agonist. The FF decreased in activated iBAT and beige tissues. The Ktrans and FF from iBAT and beige tissues were inversely correlated (r = 0.97; r = 0.94). Significant increase in vascular endothelial growth factor expression and Ktrans in activated iBAT and beige tissues were in agreement with the increased vasculature and vascular perfusion kinetics. The iBAT and beige tissues were validated by measuring molecular markers.
Conclusion
Increased Ktrans and decreased FF in iBAT and beige tissues were in agreement with the vascular perfusion kinetics facilitating the clearance of free fatty acids. The methodology can be extended for the screening of browning agents.

Epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway involved in long-term potentiation and synaptic plasticity in rats

Genevieve Saw, Kumar Krishna, Neelima Gupta, Tuck Wah Soong, Karthik Mallilankaraman, Sreedharan Sajikumar, S Thameem Dheen

Glia. 2020 Mar;68(3):656-669. doi: 10.1002/glia.23748. Epub 2019 Nov 8.

Abstract

Microglia are the main form of immune defense in the central nervous system. Microglia express phosphatidylinositol 3-kinase (PI3K), which has been shown to play a significant role in synaptic plasticity in neurons and inflammation via microglia. This study shows that microglial PI3K is regulated epigenetically through histone modifications and posttranslationally through sumoylation and is involved in long-term potentiation (LTP) by modulating the expression of brain-derived neurotrophic factor (BDNF), which has been shown to be involved in neuronal synaptic plasticity. Sodium butyrate, a histone deacetylase inhibitor, upregulates PI3K expression, the phosphorylation of its downstream effectors, AKT and cAMP response element-binding protein (CREB), and the expression of BDNF in microglia, suggesting that BDNF secretion is regulated in microglia via epigenetic regulation of PI3K. Further, knockdown of SUMO1 in BV2 microglia results in a decrease in the expression of PI3K, the phosphorylation of AKT and CREB, as well as the expression of BDNF. These results suggest that microglial PI3K is epigenetically regulated by histone modifications and posttranslationally modified by sumoylation, leading to altered expression of BDNF. Whole-cell voltage-clamp showed the involvement of microglia in neuronal LTP, as selective ablation or disruption of microglia with clodronate in rat hippocampal slices abolished LTP. However, LTP was rescued when the same hippocampal slices were treated with active PI3K or BDNF, indicating that microglial PI3K/AKT signaling contributes to LTP and synaptic plasticity. Understanding the mechanisms by which microglial PI3K influences synapses provides insights into the ways it can modulate synaptic transmission and plasticity in learning and memory.

Manipulating energy migration within single lanthanide activator forSwitchable upconversionemissions towards bidirectional photoactivation

Qingsong Mei, Akshaya Bansal, Muthu Kumara Gnanasammandhan Jayakumar, Zhiming Zhang, Jing Zhang, Hua Huang, Dejie Yu, Chrishan J. A. Ramachandra, Derek J. Hausenloy, Tuck Wah Soong & Yong Zhang

Nat Commun 10, 4416 (2019). https://doi.org/10.1038/s41467-019-12374-4

Abstract

Reliance on low tissue penetrating UV or visible light limits clinical applicability of phototherapy, necessitating use of deep tissue penetrating near-infrared (NIR) to visible light transducers like upconversion nanoparticles (UCNPs). While typical UCNPs produce multiple simultaneous emissions for unidirectional control of biological processes, programmable control requires orthogonal non-overlapping light emissions. These can be obtained through doping nanocrystals with multiple activator ions. However, this requires tedious synthesis and produces complicated multi-shell nanoparticles with a lack of control over emission profiles due to activator crosstalk. Herein, we explore cross-relaxation (CR), a non-radiative recombination pathway typically perceived as deleterious, to manipulate energy migration within the same lanthanide activator ion (Er3+) towards orthogonal red and green emissions, simply by adjusting excitation wavelength from 980 to 808 nm. These UCNPs allow programmable activation of two synergistic light-gated ion channels VChR1 and Jaws in the same cell to manipulate membrane polarization, demonstrated here for cardiac pacing.

Magnetic fields modulate metabolism and gut microbiome in correlation with Pgc‐1α expression: Follow‐up to an in vitro magnetic mitohormetic study

Yee Kit Tai, Charmaine Ng, Kristy Purnamawati, Jasmine Lye Yee Yap, Jocelyn Naixin Yin, Craig Wong, Bharati Kadamb Patel, Poh Loong Soong, Pawel Pelczar, Jürg Fröhlich, Christian Beyer, Charlene Hui Hua Fong, Sharanya Ramanan, Marco Casarosa, Carmine Pasquale Cerrato, Zi Ling Foo, Rina Malathi Pannir Selvan, Elina Grishina, Ufuk Degirmenci, Shi Jie Toh, Pete J. Richards, Ali Mirsaidi, Karin Wuertz‐Kozak, Suet Yen Chong, Stephen J. Ferguson, Adriano Aguzzi, Monica Monici, Lei Sun, Chester L. Drum, Jiong‐Wei Wang, Alfredo Franco‐Obregón

FASEB Journal. doi: 10.1096/fj.201903005RR.

Abstract

Exercise modulates metabolism and the gut microbiome. Brief exposure to low mT‐range pulsing electromagnetic fields (PEMFs) was previously shown to accentuate in vitro myogenesis and mitochondriogenesis by activating a calcium‐mitochondrial axis upstream of PGC‐1α transcriptional upregulation, recapitulating a genetic response implicated in exercise‐induced metabolic adaptations. We compared the effects of analogous PEMF exposure (1.5 mT, 10 min/week), with and without exercise, on systemic metabolism and gut microbiome in four groups of mice: (a) no intervention; (b) PEMF treatment; (c) exercise; (d) exercise and PEMF treatment. The combination of PEMFs and exercise for 6 weeks enhanced running performance and upregulated muscular and adipose Pgc‐1α transcript levels, whereas exercise alone was incapable of elevating Pgc‐1α levels. The gut microbiome Firmicutes /Bacteroidetes ratio decreased with exercise and PEMF exposure, alone or in combination, which has been associated in published studies with an increase in lean body mass. After 2 months, brief PEMF treatment alone increased Pgc‐1α and mitohormetic gene expression and after >4 months PEMF treatment alone enhanced oxidative muscle expression, fatty acid oxidation, and reduced insulin levels. Hence, short‐term PEMF treatment was sufficient to instigate PGC‐1α‐associated transcriptional cascades governing systemic mitohormetic adaptations, whereas longer‐term PEMF treatment was capable of inducing related metabolic adaptations independently of exercise.

IL-13-driven alterations in hepatic cholesterol handling contributes to hypercholesterolemia in a rat model of minimal change disease

Low LD, Lu L, Chan CY, Chen J, Yang HH, Yu H, Lee CGL, Ng KH, Yap HK.

Clin Sci (Lond). 2020 Jan 31;134(2):225-237. doi: 10.1042/CS20190961.

Abstract

Circulating factors have been implicated in the pathogenesis of minimal change disease (MCD), and may have direct effects on cholesterol metabolism. This study investigated the pathogenesis of hypercholesterolemia in an IL-13 overexpression rat model of MCD prior to the onset of proteinuria, so as to establish the direct contribution of IL-13, especially with regard to hepatic cholesterol handling. In this model of MCD, the temporal relationship between hypercholesterolemia and proteinuria was first identified. Plasma proprotein convertase subtilisin/kexin type 9 (Pcsk9) and liver ATP-binding cassette sub-family G member 5 (Abcg5) were measured using ELISA. Liver Ldlr and liver X receptor alpha (Lxra) were quantified with Western blot. Abcg5-mediated cholesterol efflux in IL-13-stimulated rat primary hepatocytes was measured using taurocholate as cholesterol acceptor. The role of Lxra was validated using a luciferase assay in Lxre-luciferase-transfected IL-13-stimulated hepatocytes. IL-13-transfected rats developed hypercholesterolemia prior to proteinuria, with 35% of rats hypercholesterolemic but only 11% proteinuric by Day 20 (P = 0.04). These pre-proteinuric hypercholesterolemic rats showed elevations in total and LDL-cholesterol, but not hypertriglyceridemia or hepatic steatosis. The hypercholesterolemia was associated with increased hepatic Pcsk9 synthesis and enhanced circulating Pcsk9 levels, which correlated strongly with plasma total cholesterol (r = 0.73, P<0.001). The hypercholesterolemia was also contributed by decreased Abcg5 expression and activity, due to reduced Lxra expression. Lxra expression correlated with plasma total cholesterol levels (r = -0.52, P = 0.01), and overexpression of pLxra in rat hepatocytes abrogated the IL-13-mediated down-regulation of Lxre-driven gene expression. In conclusion, we have shown that IL-13 induced changes in hepatic cholesterol handling in a cytokine-induced rat model of MCD, resulting in hypercholesterolemia which can precede the onset of proteinuria.

Destroy, what destroys you

Luu K, Nickles E, Schwarz H

Oncoimmunology. 2019 Nov 3;9(1):1685301. doi: 10.1080/2162402X.2019.1685301. eCollection 2020.

Abstract

New evidence indicates the importance of CD137 for controlling Epstein-Barr virus (EBV) infections. (1) Mutations in CD137 predispose to EBV-associated diseases. (2) EBV induces ectopic CD137 expression, thereby activating a negative feed-back regulation and reducing T cell costimulation. These findings suggest CD137 agonists as new treatments for EBV-associated diseases.

Targeting autophagy using natural compounds for cancer prevention and therapy

Deng S, Shanmugam MK, Kumar AP, Yap CT, Sethi G, Bishayee A.

Cancer. 2019 Apr 15;125(8):1228-1246. doi: 10.1002/cncr.31978.

Abstract

Autophagy, also known as macroautophagy, is a tightly regulated process involved in the stress responses, such as starvation. It is a vacuolar, lysosomal pathway for the degradation of damaged proteins and organelles in eukaryotic cells. Autophagy also plays a key role in various tissue processes and immune responses and in the regulation of inflammation. Over the past decade, three levels of autophagy regulation have been identified in mammalian cells: 1) signaling, 2) autophagosome formation, and 3) autophagosome maturation and lysosomal degradation. Any deregulation of the autophagy processes can lead to the development of diverse chronic diseases, such as diabetes, obesity, cardiovascular disease, neurodegenerative disease, and malignancies. However, the potential role of autophagy in cancer is rather complex and has been associated with both the induction and the inhibition of neoplasia. Several synthetic autophagy modulators have been identified as promising candidates for cancer therapy. In addition, diverse phytochemicals derived from natural sources, such as curcumin, ursolic acid, resveratrol, thymoquinone, and γ-tocotrienol, also have attracted attention as promising autophagy modulators with minimal side effects. In this review, the authors discuss the importance of autophagy regulators and various natural compounds that induce and/or inhibit autophagy in the prevention and therapy of cancer.

Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems

Tavakol S, Ashrafizadeh M, Deng S, Azarian M, Abdoli A, Motavaf M, Poormoghadam D, Khanbabaei H, Afshar EG, Mandegary A, Pardakhty A, Yap CT, Mohammadinejad R, Kumar AP.

Biomolecules. 2019 Sep 25;9(10). pii: E530. doi: 10.3390/biom9100530.

Abstract

Autophagy modulation is considered to be a promising programmed cell death mechanism to prevent and cure a great number of disorders and diseases. The crucial step in designing an effective therapeutic approach is to understand the correct and accurate causes of diseases and to understand whether autophagy plays a cytoprotective or cytotoxic/cytostatic role in the progression and prevention of disease. This knowledge will help scientists find approaches to manipulate tumor and pathologic cells in order to enhance cellular sensitivity to therapeutics and treat them. Although some conventional therapeutics suffer from poor solubility, bioavailability and controlled release mechanisms, it appears that novel nanoplatforms overcome these obstacles and have led to the design of a theranostic-controlled drug release system with high solubility and active targeting and stimuli-responsive potentials. In this review, we discuss autophagy modulators-related signaling pathways and some of the drug delivery strategies that have been applied to the field of therapeutic application of autophagy modulators. Moreover, we describe how therapeutics will target various steps of the autophagic machinery. Furthermore, nano drug delivery platforms for autophagy targeting and co-delivery of autophagy modulators with chemotherapeutics/siRNA, are also discussed.

Solar radiation and the validity of infrared tympanic temperature during exercise in the heat.

Otani H, Kaya M, Tamaki A, Hosokawa Y, Lee JKW

Int J Biometeorol. 2019 Nov 9. doi: 10.1007/s00484-019-01791-1. [Epub ahead of print]

Abstract

We investigated the validity of infrared tympanic temperature (IR-Tty) during exercise in the heat with variations in solar radiation. Eight healthy males completed stationary cycling trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30°C with 50% relative humidity. Three solar radiation conditions, 0, 250 and 500 W/m2, were tested using a ceiling-mounted solar simulator (metal-halide lamps) over a 3 × 2 m irradiated area. IR-Tty and rectal temperature (Tre) were similar before and during exercise in each trial (P > 0.05). Spearman's rank correlation coefficient (rs) demonstrated very strong (250 W/m2, rs = 0.87) and strong (0 W/m2, rs = 0.73; 500 W/m2, rs = 0.78) correlations between IR-Tty and Tre in all trials (P < 0.001). A Bland-Altman plot showed that mean differences (SD; 95% limits of agreement; root mean square error) between IR-Tty and Tre were - 0.11°C (0.46; - 1.00 to 0.78°C; 0.43 ± 0.16°C) in 0 W/m2, - 0.13°C (0.32; - 0.77 to 0.50°C; 0.32 ± 0.10°C) in 250 W/m2 and - 0.03°C (0.60; - 1.21 to 1.14°C; 0.46 ± 0.27°C) in 500 W/m2. A positive correlation was found in 500 W/m2 (rs = 0.51; P < 0.001) but not in 250 W/m2 (rs = 0.04; P = 0.762) and 0 W/m2 (rs = 0.04; P = 0.732), indicating a greater elevation in IR-Tty than Tre in 500 W/m2. Percentage of target attainment within ± 0.3°C between IR-Tty and Tre was higher in 250 W/m2 (100 ± 0%) than 0 (93 ± 7%) and 500 (90 ± 10%; P < 0.05) W/m2. IR-Tty is acceptable for core temperature monitoring during exercise in the heat when solar radiation is ≤ 500 W/m2, and its accuracy increases when solar radiation is 250 W/m2 under our study conditions.

Workplace Heat: An increasing threat to occupational health and productivityntries during climate change.

Kjellstrom, T, Lemke, B, Lee, JKW.

American Journal Industrial Medicine, 62 (12): 1076-1078. doi: 10.1002/ajim.23051

Abstract

No abstract is available for this article.

Activation of microglia in acute hippocampal slices affects activity-dependent long-term potentiation and synaptic tagging and capture in area CA1.

Raghuraman R, Karthikeyan A, Wei WL, Dheen ST, Sajikumar S.

Neurobiol Learn Mem. 2019 Sep;163:107039. doi: 10.1016/j.nlm.2019.107039. Epub 2019 Jul 3.

Abstract

Activity dependent setting of synaptic tags is critical for the establishment and maintenance of long-term plasticity and its associative properties such as synaptic tagging and capture (STC), a widely studied cellular model of associative memory. Although the known mechanisms of STC such as setting of synaptic tags or distribution of plasticity related proteins (PRPs) are the processes mainly happening within the neuronal compartments, the role of non-neuronal components is still elusive. Here, we report that microglia has a specific role in setting the synaptic tags and thus promotes long-term plasticity and STC. Treatment of hippocampal slices with clodronate, a specific inhibitor of microglia, resulted in an activated morphology of microglia but not of the hippocampal pyramidal neurons, oligodendrocytes or astrocytes. Activation of microglia before or 60 min after the induction of long-term plasticity prevented its maintenance and thus the expression of STC. Interestingly, activation of microglia 2 h after the induction of long-term plasticity neither prevented its maintenance nor its associative interaction with activated nearby synaptic populations. Given the half-life of synaptic tags is until about 60-90 min, activation of microglia beyond this time point while the maintenance phase is still unperturbed, suggests a lack of microglial interference in the synthesis or trigger of plasticity related products. Thus, our study provides the first evidence that microglia play a critical role in the setting of synaptic tags during the early phase of activity dependent plasticity.

MicroRNA-134-5p inhibition rescues long-term plasticity and synaptic tagging/capture in an Aβ(1-42)-induced model of Alzheimer's disease.

Baby N, Alagappan N, Dheen ST, Sajikumar S.

Aging Cell. 2019 Oct 17:e13046. doi: 10.1111/acel.13046. [Epub ahead of print]

Abstract

Progressive memory loss is one of the most common characteristics of Alzheimer's disease (AD), which has been shown to be caused by several factors including accumulation of amyloid β peptide (Aβ) plaques and neurofibrillary tangles. Synaptic plasticity and associative plasticity, the cellular basis of memory, are impaired in AD. Recent studies suggest a functional relevance of microRNAs (miRNAs) in regulating plasticity changes in AD, as their differential expressions were reported in many AD brain regions. However, the specific role of these miRNAs in AD has not been elucidated. We have reported earlier that late long-term potentiation (late LTP) and its associative mechanisms such as synaptic tagging and capture (STC) were impaired in Aβ (1-42)-induced AD condition. This study demonstrates that expression of miR-134-5p, a brain-specific miRNA is upregulated in Aβ (1-42)-treated AD hippocampus. Interestingly, the loss of function of miR-134-5p restored late LTP and STC in AD. In AD brains, inhibition of miR-134-5p elevated the expression of plasticity-related proteins (PRPs), cAMP-response-element binding protein (CREB-1) and brain-derived neurotrophic factor (BDNF), which are otherwise downregulated in AD condition. The results provide the first evidence that the miR-134-mediated post-transcriptional regulation of CREB-1 and BDNF is an important molecular mechanism underlying the plasticity deficit in AD; thus demonstrating the critical role of miR-134-5p as a potential therapeutic target for restoring plasticity in AD condition.

Epigenetic regulation of microglial phosphatidylinositol 3-kinase pathway involved in long-term potentiation and synaptic plasticity in rats.

Saw G, Krishna K, Gupta N, Soong TW, Mallilankaraman K, Sajikumar S, Dheen ST.

Glia. 2019 Nov 8. doi: 10.1002/glia.23748. [Epub ahead of print]

Abstract

CD137L-DCs, Potent Immune-Stimulators-History, Characteristics, and Perspectives.

Zeng Q, Zhou Y, Schwarz H.

Front Immunol. 2019 Oct 2;10:2216. doi: 10.3389/fimmu.2019.02216. eCollection 2019.

Abstract

Dendritic cell (DC)-based immunotherapies are being explored for over 20 years and found to be very safe. Most often, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4)-induced monocyte-derived DCs (moDCs) are being used, which have demonstrated some life-prolonging benefit to patients of multiple tumors. However, the limited clinical response and efficacy call for the development of more potent DCs. CD137L-DC may meet this demand. CD137L-DCs are a novel type of monocyte-derived inflammatory DCs that are induced by CD137 ligand (CD137L) agonists. CD137L is expressed on the surface of antigen-presenting cells, including monocytes, and signaling of CD137L into monocytes induces their differentiation to CD137L-DCs. CD137L-DCs preferentially induce type 1 T helper (Th1) cell polarization and strong type 1 CD8+ T cell (Tc1) responses against tumor-associated viral antigens. The in vitro T cell-stimulatory capacity of CD137L-DCs is superior to that of conventional moDCs. The transcriptomic profile of CD137L-DC is highly similar to that of in vivo DCs at sites of inflammation. The strict activation dependence of CD137 expression and its restricted expression on activated T cells, NK cells, and vascular endothelial cells at inflammatory sites make CD137 an ideally suited signal for the induction of monocyte-derived inflammatory DCs in vivo. These findings and their potency encouraged a phase I clinical trial of CD137L-DCs against Epstein-Barr virus-associated nasopharyngeal carcinoma. In this review, we introduce and summarize the history, the characteristics, and the transcriptional profile of CD137L-DC, and discuss the potential development and applications of CD137L-DC.

Development of a Bispecific Antibody Targeting CD30 and CD137 on Hodgkin and Reed-Sternberg Cells.

Rajendran S, Li Y, Ngoh E, Wong HY, Cheng MS,2, Wang CI, Schwarz H.

Front Oncol. 2019 Sep 24;9:945. doi: 10.3389/fonc.2019.00945. eCollection 2019.

Abstract

Hodgkin Lymphoma (HL) is a malignancy that frequently affects young adults. Although, there are effective treatments not every patient responds, necessitating the development of novel therapeutic approaches, especially for relapsed and refractory cases. The two TNF receptor family members CD30 and CD137 are expressed on Hodgkin and Reed Sternberg (HRS) cells, the malignant cells in HL. We found that this co-expression is specific for HRS cells. Based on this discovery we developed a bispecific antibody that binds preferentially to the CD30, CD137-double positive HRS cells. The CD30, CD137 bispecific antibody gets internalized into HRS cells opening up the possibility to use it as a carrier for a toxin. This antibody also induces antibody-dependent, cell-mediated cytotoxicity in CD30, CD137-double positive HRS cells. The enhances specificity of the CD30, CD137 bispecific antibody to HRS cells makes it a promising candidate for development as a novel HL treatment.

Heart Rate Measures From Wrist-Worn Activity Trackers in a Laboratory and Free-Living Setting: Validation Study.

Müller AM, Wang NX, Yao J, Tan CS, Low ICC, Lim N, Tan J, Tan A, Müller-Riemenschneider F.

JMIR Mhealth Uhealth. 2019 Oct 2;7(10):e14120. doi: 10.2196/14120.

Abstract

BACKGROUND:
Wrist-worn activity trackers are popular, and an increasing number of these devices are equipped with heart rate (HR) measurement capabilities. However, the validity of HR data obtained from such trackers has not been thoroughly assessed outside the laboratory setting.
OBJECTIVE:
This study aimed to investigate the validity of HR measures of a high-cost consumer-based tracker (Polar A370) and a low-cost tracker (Tempo HR) in the laboratory and free-living settings.
METHODS:
Participants underwent a laboratory-based cycling protocol while wearing the two trackers and the chest-strapped Polar H10, which acted as criterion. Participants also wore the devices throughout the waking hours of the following day during which they were required to conduct at least one 10-min bout of moderate-to-vigorous physical activity (MVPA) to ensure variability in the HR signal. We extracted 10-second values from all devices and time-matched HR data from the trackers with those from the Polar H10. We calculated intraclass correlation coefficients (ICCs), mean absolute errors, and mean absolute percentage errors (MAPEs) between the criterion and the trackers. We constructed decile plots that compared HR data from Tempo HR and Polar A370 with criterion measures across intensity deciles. We investigated how many HR data points within the MVPA zone (≥64% of maximum HR) were detected by the trackers.
RESULTS:
Of the 57 people screened, 55 joined the study (mean age 30.5 [SD 9.8] years). Tempo HR showed moderate agreement and large errors (laboratory: ICC 0.51 and MAPE 13.00%; free-living: ICC 0.71 and MAPE 10.20%). Polar A370 showed moderate-to-strong agreement and small errors (laboratory: ICC 0.73 and MAPE 6.40%; free-living: ICC 0.83 and MAPE 7.10%). Decile plots indicated increasing differences between Tempo HR and the criterion as HRs increased. Such trend was less pronounced when considering the Polar A370 HR data. Tempo HR identified 62.13% (1872/3013) and 54.27% (5717/10,535) of all MVPA time points in the laboratory phase and free-living phase, respectively. Polar A370 detected 81.09% (2273/2803) and 83.55% (9323/11,158) of all MVPA time points in the laboratory phase and free-living phase, respectively.
CONCLUSIONS:
HR data from the examined wrist-worn trackers were reasonably accurate in both the settings, with the Polar A370 showing stronger agreement with the Polar H10 and smaller errors. Inaccuracies increased with increasing HRs; this was pronounced for Tempo HR.

Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.

Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.

Biomaterials. 2019 May;201:16-32. doi: 10.1016/j.biomaterials.2019.01.046.

Abstract

Interconnected macroporous hydrogel is hydrophilic; it exhibits soft tissue-like mechanical property and aqueous-stable macroporosity for 3D spheroid culture. There is an unmet need to develop cleavable macroporous hydrogel, for the ease of retrieving functional spheroids for further in vitro and in vivo applications. We have developed and comprehensively characterized a hydroxypropyl-cellulose-disulfide sponge by systematically identifying strategies and synthesis schemes to confer cleavability to the sponge under cell-friendly conditions. It preserved the essential advantages of the macroporous hydrogel to support 3D spheroid formation and maintenance of sensitive hepatocytes while allowing rapid cleavage and retrieval of functional spheroids. By culturing HepaRG as spheroids in the cleavable sponge, we have accelerated HepaRG differentiation to 9 days compared to 28 days in 2D culture. Cytochrome P450 basal activity reached significantly higher level, while albumin secretion and fluorescein diacetate staining indicated the same at day 5. The purity of albumin+ hepatocytes reached 92.9% versus 7.1% of CK19+ cholangiocytes at day 9, a much stronger preference for hepatocytes than the 60% albumin+ hepatocytes purity in 2D culture. HepaRG differentiated hepatocytes were retrieved by cleaving the sponge with 10 mM tris-(2-carboxyethyl)-phosphine (TCEP) within 30 min preserving viability, plateability and positive albumin staining of the hepatocyte spheroids. This cleavable macroporous hydrogel sponge will support the rapid development of various 3D spheroid- or organoid-based applications in basic research and drug testing.

Sequential drug delivery for liver diseases.

Huang X, Lee F, Teng Y, Lingam CB, Chen Z, Sun M, Song Z, Balachander GM, Leo HL, Guo Q, Shah I, Yu H.

Adv Drug Deliv Rev. 2019 Sep - Oct;149-150:72-84. doi: 10.1016/j.addr.2019.11.001.

Abstract

The liver performs critical physiological functions such as metabolism/detoxification and blood homeostasis/biliary excretion. A high degree of blood access means that a drug's resident time in any cell is relatively short. This short drug exposure to cells requires local sequential delivery of multiple drugs for optimal efficacy, potency, and safety. The high metabolism and excretion of drugs also impose both technical challenges and opportunities to sequential drug delivery. This review provides an overview of the sequential events in liver regeneration and the related liver diseases. Using selected examples of liver cancer, hepatitis B viral infection, fatty liver diseases, and drug-induced liver injury, we highlight efforts made for the sequential delivery of small and macromolecular drugs through different biomaterials, cells, and microdevice-based delivery platforms that allow fast delivery kinetics and rapid drug switching. As this is a nascent area of development, we extrapolate and compare the results with other sequential drug delivery studies to suggest possible application in liver diseases, wherever appropriate.

Pathogenic Bhlhe40+ GM-CSF+ CD4+ T Cells Promote Indirect Alloantigen Presentation in the GI Tract during GVHD.

Piper C, Zhou V, Komorowski R, Szabo A, Vincent B, Serody J, Alegre ML, Edelson BT, Taneja R, Drobyski WR.

Blood. 2019 Dec 27. pii: blood.2019001696. doi: 10.1182/blood.2019001696. [Epub ahead of print]

Abstract

Gastrointestinal (GI) tract involvement is the major cause of morbidity and mortality in acute graft versus host disease (GVHD) and pathological damage is largely attributable to inflammatory cytokine production. Recently, GM-CSF has been identified as a cytokine that mediates inflammation in the GI tract, but the transcriptional program that governs GM-CSF production and the mechanism by which GM-CSF links adaptive to innate immunity within this tissue site have not been defined. In the current study, we identified Bhlhe40 as a key transcriptional regulator that governs GM-CSF production by CD4+ T cells and mediates pathological damage in the GI tract during GVHD. In addition, we observed that GM-CSF was not regulated by either IL-6 or IL-23 which are both potent inducers of GVHD-induced colonic pathology, indicating that GM-CSF constitutes a nonredundant inflammatory pathway in the GI tract. Mechanistically, GM-CSF had no adverse effect on regulatory T cell reconstitution, but linked adaptive to innate immunity by enhancing the activation of donor-derived dendritic cells in the colon and subsequent accumulation of these cells in the mesenteric lymph nodes. In addition, GM-CSF promoted indirect alloantigen presentation resulting in the accumulation of donor-derived T cells with a proinflammatory cytokine phenotype in the colon. Thus, Bhlhe40+ GM-CSF+ CD4+ T cells constitute a colitogenic T cell population that promotes indirect alloantigen presentation and pathological damage within the GI tract, positioning GM-CSF as a key regulator of GVHD in the colon and a potential therapeutic target for amelioration of this disease.

Interweaving Tumor Heterogeneity into the Cancer Epigenetic/Metabolic Axis.

Leung JY, Chia K, Ong DST, Taneja R.

Antioxid Redox Signal. 2019 Dec 16. doi: 10.1089/ars.2019.7942. [Epub ahead of print]

Abstract

Significance: The epigenomic/metabolic landscape in cancer has been studied extensively in the past decade and forms the basis of various drug targets. Yet, cancer treatment remains a challenge, with clinical trials exhibiting limited efficacy and high relapse rates. Patients respond differently to therapy, which is fundamentally attributed to tumor heterogeneity, both across and within tumors. This review focuses on the interactions between the heterogeneous tumor microenvironment (TME) and the epigenomic/metabolic axis in cancer, as well as the emerging technologies under development to aid heterogeneity studies. Recent Advances: Interlinks between epigenetics and metabolism in cancer have been reported. Emerging studies have unveiled interactions between the TME and cancer cells that play a critical role in regulating epigenetics and reprogramming cancer metabolism, suggesting a three-way cross talk. Critical Issues: This cross talk accentuates the multiplex nature of cancer, and the importance of considering tumor heterogeneity in various epigenomic/metabolic cancer studies. Future Directions: With the advancement in single-cell profiling, it may be possible to identify cancer subclones and their unique vulnerabilities to develop a multimodal therapy. Drugs targeting the TME are currently being studied, and a better understanding of the TME in regulating cancer epigenetics and metabolism may hold the key to identifying novel therapeutic targets.

Aurora kinase A-mediated phosphorylation of mPOU at a specific site drives skeletal muscle differentiation.

Karthigeyan D, Bose A, Boopathi R, Rao VJ, Shima H, Bharathy N, Igarashi K, Taneja R, Trivedi AK, Kundu TK.

J Biochem. 2019 Oct 30. pii: mvz088. doi: 10.1093/jb/mvz088. [Epub ahead of print]

Abstract

Aurora kinases are Ser/Thr-directed protein kinases which play pivotal roles in mitosis. Recent evidences highlight the importance of these kinases in multiple biological events including skeletal muscle differentiation. Our earlier study identified the transcription factor POU6F1 (or mPOU) as a novel Aurora kinase (Aurk) A substrate. Here, we report that AurkA phosphorylates mPOU at Ser197 and inhibit its DNA binding ability. Delving into mPOU physiology, we find that the phospho-mimic (S197D) mPOU mutant exhibits enhancement, while the wild type (WT) or the phospho-deficient mutant shows retardation in C2C12 myoblast differentiation. Interestingly, POU6F1 depletion phenocopies S197D-mPOU overexpression in the differentiation context. Collectively, our results signify mPOU as a negative regulator of skeletal muscle differentiation and strengthen the importance of AurkA in skeletal myogenesis.

Mitochondrial Dysfunction at the Center of Cancer Therapy

Chiu HY, Tay EXY, Ong DST, Taneja R

Antioxid Redox Signal. 2019 Nov 4. doi: 10.1089/ars.2019.7898. [Epub ahead of print]

Abstract

Significance: Mitochondria undergo constant morphological changes through fusion, fission, and mitophagy. As the key organelle in cells, mitochondria are responsible for numerous essential cellular functions such as metabolism, regulation of calcium (Ca2+), generation of reactive oxygen species, and initiation of apoptosis. Unsurprisingly, mitochondrial dysfunctions underlie many pathologies including cancer. Recent Advances: Currently, the gold standard for cancer treatment is chemotherapy, radiation, and surgery. However, the efficacy of these treatments varies across different cancer cells. It has been suggested that mitochondria may be at the center of these diverse responses. In the past decade, significant advances have been made in understanding distinct types of mitochondrial dysfunctions in cancer. Through investigations of underlying mechanisms, more effective treatment options are developed. Critical Issues: We summarize various mitochondria dysfunctions in cancer progression that have led to the development of therapeutic options. Current mitochondrial-targeted therapies and challenges are discussed. Future Directions: To address the "root" of cancer, utilization of mitochondrial-targeted therapy to target cancer stem cells may be valuable. Investigation of other areas such as mitochondrial trafficking may offer new insights into cancer therapy. Moreover, common antibiotics could be explored as mitocans, and synthetic lethality screens can be utilized to overcome the plasticity of cancer cells.

Role of formyl peptide receptor 2 (FPR2) in the normal brain and in neurological conditions

Ong WY, Chua JJE

Neural Regeneration Research. 2019 Dec;14(12):2071-2072. doi: 10.4103/1673-5374.262575.

Abstract

There is much recent interest in the role of the anti-inflammatory molecules and their receptors in the normal brain and in neurological disorders. The formyl peptide receptor (FPR) subfamily of G protein-coupled receptors play important roles in these processes. Binding to specific peptides triggers activation of FPRs, leading to signalling events that regulate inflammatory responses. One member of this subfamily of receptors is FPR2, also known as ALX (the lipoxin A4 (LXA4) receptor). FPR2 is specifically activated by LXA4 and resolvin D1 (RvD1) (Pirault and Bäck, 2018). LXA4 is an anti-inflammatory molecule produced by the action of lipoxygenases on arachidonic acid, while RvD1 is produced by the action of lipoxygenases on docosahexaenoic acid, a component of fish oil. Activation of FPR2 by LXA4 or RvD1 triggers downstream signalling cascades, e.g., inhibition of calcium-calmodulin dependent protein kinase and p38 mitogen-activated protein kinase phosphorylation, leading to a reduction in inflammatory responses. Annexin A1 (ANXA1) is another molecule which could interact with FPR2. A Ca 2+-dependent phospholipid-binding protein, ANXA1 suppresses phospholipase A2 activity to reduce arachidonic acid and eicosanoid production and decrease leukocyte inflammatory events such as cell migration, chemotaxis, phagocytosis and respiratory burst. While many studies have shown that binding to FPR2 is a chemotactic signal to attract macrophages to the site of tissue injury, other studies have highlighted that it is part of an anti-inflammatory process. For example, from some of the studies detailed below (summarized in [Figure 1]), it seems that activation of this receptor does not itself cause further production of pro-inflammatory mediators by macrophages. Instead, FPR2 appears to attract macrophages and other immune cells to the site of tissue injury to initiate a “quiet mopping-up process” to resolve inflammation.

Hepatic spheroids used as an in vitro model to study malaria relapse

Chua ACY, Ananthanarayanan A, Ong JJY, Wong JY, Yip A, Singh NH, Qu Y, Dembele L, McMillian M, Ubalee R, Davidson S, Tungtaeng A, Imerbsin R, Gupta K, Andolina C, Lee F, S-W Tan K, Nosten F, Russell B, Lange A, Diagana TT, Rénia L, Yeung BKS, Yu H, Bifani P

Biomaterials. 2019 Sep;216:119221. doi: 10.1016/j.biomaterials.2019.05.032.

Abstract

Hypnozoites are the liver stage non-dividing form of the malaria parasite that are responsible for relapse and acts as a natural reservoir for human malaria Plasmodium vivax and P. ovale as well as a phylogenetically related simian malaria P. cynomolgi. Our understanding of hypnozoite biology remains limited due to the technical challenge of requiring the use of primary hepatocytes and the lack of robust and predictive in vitro models. In this study, we developed a malaria liver stage model using 3D spheroid-cultured primary hepatocytes. The infection of primary hepatocytes in suspension led to increased infectivity of both P. cynomolgi and P. vivax infections. We demonstrated that this hepatic spheroid model was capable of maintaining long term viability, hepatocyte specific functions and cell polarity which enhanced permissiveness and thus, permitting for the complete development of both P. cynomolgi and P. vivax liver stage parasites in the infected spheroids. The model described here was able to capture the full liver stage cycle starting with sporozoites and ending in the release of hepatic merozoites capable of invading simian erythrocytes in vitro. Finally, we showed that this system can be used for compound screening to discriminate between causal prophylactic and cidal antimalarials activity in vitro for relapsing malaria.

Self‐assembling amyloid‐like peptides as exogenous second harmonic probes for bioimaging applications

Ni M, Zhuo S, Iliescu C, So PTC, Mehta JS, Yu H, Hauser CAE

Journal of Biophotonics. 2019 Jun 4:e201900065. doi: 10.1002/jbio.201900065.

Abstract

Amyloid‐like peptides are an ideal model for the mechanistic study of amyloidosis, which may lead to many human diseases, such as Alzheimer disease. This study reports a strong second harmonic generation (SHG) effect of amyloid‐like peptides, having a signal equivalent to or even higher than those of endogenous collagen fibers. Several amyloid‐like peptides (both synthetic and natural) were examined under SHG microscopy and shown they are SHG‐active. These peptides can also be observed inside cells (in vitro). This interesting property can make these amyloid‐like peptides second harmonic probes for bioimaging applications. Furthermore, SHG microscopy can provide a simple and label‐free approach to detect amyloidosis. Lattice corneal dystrophy was chosen as a model disease of amyloidosis. Morphological difference between normal and diseased human corneal biopsy samples can be easily recognized, proving that SHG can be a useful tool for disease diagnosis.

Studying nucleic envelope and plasma membrane mechanics of eukaryotic cells using confocal reflectance interferometric microscopy.

Singh VR, Yang YA, Yu H, Kamm RD, Yaqoob Z, So PTC

Nature Communications. 2019 Aug 13;10(1):3652. doi: 10.1038/s41467-019-11645-4.

Abstract

Mechanical stress on eukaryotic nucleus has been implicated in a diverse range of diseases including muscular dystrophy and cancer metastasis. Today, there are very few non-perturbative methods to quantify nuclear mechanical properties. Interferometric microscopy, also known as quantitative phase microscopy (QPM), is a powerful tool for studying red blood cell biomechanics. The existing QPM tools, however, have not been utilized to study biomechanics of complex eukaryotic cells either due to lack of depth sectioning, limited phase measurement sensitivity, or both. Here, we present depth-resolved confocal reflectance interferometric microscopy as the next generation QPM to study nuclear and plasma membrane biomechanics. The proposed system features multiple confocal scanning foci, affording 1.5 micron depth-resolution and millisecond frame rate. Furthermore, a near common-path interferometer enables quantifying nanometer-scale membrane fluctuations with better than 200 picometers sensitivity. Our results present accurate quantification of nucleic envelope and plasma membrane fluctuations in embryonic stem cells.

The Progress of Investigating the CD137-CD137L Axis as a Potential Target for Systemic Lupus Erythematosus.

Mak A, Schwarz H

Cells. 2019 Sep 6;8(9). pii: E1044. doi: 10.3390/cells8091044.

Abstract

Costimulatory molecules facilitate cross-talks among leukocytes via mutual stimulatory and inhibitory signalling, contributing to diverse immunological outcomes in normal physiological responses and pathological conditions. Systemic lupus erythematosus (SLE) is a complex multi-systemic autoimmune condition in which cellular communication through the involvement of costimulatory molecules is crucial in driving proinflammatory responses from the stage of autoantigen presentation to the subsequent process of pathogenic autoantibody production. While the physiology of the costimulatory systems including OX40-OX40L, CD28/CTLA-4-CD80/86, ICOS-B7RP1 and CD70-CD27 has been relatively well studied in SLE, recent data on the immunopathology of the CD137-CD137 ligand (CD137L) system in murine lupus models and patients with SLE highlight the critical role of this costimulatory system in initiating and perpetuating the diverse clinical and serological phenotypes of SLE. CD137, a membrane-bound receptor which belongs to the tumour necrosis factor receptor superfamily, is mainly expressed on activated T cells. Activation of the CD137 receptor via its interaction with CD137L which is expressed on antigen present cells (APC) including B cells, triggers bi-directional signalling; that is, signalling through CD137 as well as signalling through CD137L (reverse signalling), which further activates T cells and polarizes them to the Th1/Tc1 pathway. Further, via reverse CD137L signalling it enhances differentiation and maturation of the APC, particularly of dendritic cells, which subsequently drive proinflammatory cytokine production. In this review, recent data including our experience in the manipulation of CD137L signalling pertaining to the pathophysiology of SLE will be critically reviewed. More in-depth understanding of the biology of the CD137-CD137L co-stimulation system opens an opportunity to identify new prognostic biomarkers and the design of novel therapeutic approaches for advancing the management of SLE.

Deletion of CD137 Ligand Exacerbates Renal and Cutaneous but Alleviates Cerebral Manifestations in Lupus.

Mak A, Dharmadhikari B, Kow NY, Thamboo TP, Tang Q, Wong LW, Sajikumar S, Wong HY, Schwarz H.

Frontiers in Immunology. 2019 Jun 26;10:1411. doi: 10.3389/fimmu.2019.01411. eCollection 2019.

Abstract

The CD137—CD137 ligand (CD137L) costimulatory system is a critical immune checkpoint with pathophysiological implications in autoimmunity. In this study, we investigated the role of CD137L-mediated costimulation on renal, cutaneous and cerebral manifestations in lupus and the underlying immunological mechanism. Lupus-prone C57BL/6lpr−/− (B6.lpr) mice were crossed to C57BL/6.CD137L−/− mice to obtain CD137L-deficient B6.lpr [double knock out (DKO)] mice. We investigated the extent of survival, glomerulonephritis, skin lesions, cerebral demyelination, immune deviation and long-term synaptic plasticity among the two mouse groups. Cytokine levels, frequency of splenic leukocyte subsets and phenotypes were compared between DKO, B6.lpr and B6.WT mice. A 22 month observation of 226 DKO and 137 B6.lpr mice demonstrated significantly more frequent proliferative glomerulonephritis, larger skin lesions and shorter survival in DKO than in B6.lpr mice. Conversely, microglial activation and cerebral demyelination were less pronounced while long-term synaptic plasticity, was superior in DKO mice. Splenic Th17 cells were significantly higher in DKO than in B6.lpr and B6.WT mice while Th1 and Th2 cell frequencies were comparable between DKO and B6.lpr mice. IL-10 and IL-17 expression by T cells was not affected but there were fewer IL-10-producing myeloid (CD11b+) cells, and also lower serum IL-10 levels in DKO than in B6.lpr mice. The absence of CD137L causes an immune deviation toward Th17, fewer IL-10-producing CD11b+ cells and reduced serum IL-10 levels which potentially explain the more severe lupus in DKO mice while leading to reduced microglia activation, lesser cerebral damage and less severe neurological deficits.

Increased Akt-Driven Glycolysis Is the Basis for the Higher Potency of CD137L-DCs.

Zeng Q, Mallilankaraman K, Schwarz H.

Frontiers in Immunology. 2019 Jun 26;10:1411. doi: 10.3389/fimmu.2019.01411. eCollection 2019.

Abstract

CD137 ligand-induced dendritic cells (CD137L-DCs) are a new type of dendritic cells (DCs) that induce strong cytotoxic T cell responses. Investigating the metabolic activity as a potential contributing factor for their potency, we find a significantly higher rate of glycolysis in CD137L-DCs than in granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 4 induced monocyte-derived DCs (moDCs). Using unbiased screening, Akt-mTORC1 activity was found to be significantly higher throughout the differentiation and maturation of CD137L-DCs than that of moDCs. Furthermore, this higher activity of the Akt-mTORC1 pathway is responsible for the significantly higher glycolysis rate in CD137L-DCs than in moDCs. Inhibition of Akt during maturation or inhibition of glycolysis during and after maturation resulted in suppression of inflammatory DCs, with mature CD137L-DCs being the most affected ones. mTORC1, instead, was indispensable for the differentiation of both CD137L-DCs and moDCs. In contrast to its role in supporting lipid synthesis in murine bone marrow-derived DCs (BMDCs), the higher glycolysis rate in CD137L-DCs does not lead to a higher lipid content but rather to an accumulation of succinate and serine. These data demonstrate that the increased Akt-driven glycolysis underlies the higher activity of CD137L-DCs.

Epstein-Barr virus-encoded LMP1 induces ectopic CD137 expression on Hodgkin and Reed-Sternberg cells via the PI3K-AKT-mTOR pathway.

Priya Aravinth S, Rajendran S, Li Y, Wu M, Yi Wong AH, Schwarz H.

Leukemia & Lymphoma. 2019 May 6:1-8. doi: 10.1080/10428194.2019.1607330. [Epub ahead of print]

Abstract

CD137 is a potent co-stimulatory molecule on activated T cells, and its ligand (CD137L) is expressed on antigen presenting cells (APC). Ectopic expression of CD137 has been identified on Hodgkin Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin Lymphoma (HL), and CD137 on HRS cells was found to support growth of HRS cells and escape from immune surveillance. HRS cells are mostly derived from B cells, which poses the question of how B cells acquire ectopic CD137 expression during the transformation process. HL is associated with Epstein-Barr virus (EBV) infection. We show that the EBV latent membrane protein 1 (LMP1) induces expression of CD137 in HRS cell lines. In a HL tissue microarray, 96% of the CD137-positive HL cases stained positive for LMP1. LMP1 utilizes the PI3K-AKT-mTOR pathway for inducing CD137 expression. These findings support the role of EBV in HL pathogenesis.

Mitochondria-Targeted Two-Photon Fluorescent Photosensitizers for Cancer Cell Apoptosis via Spatial Selectability.

Ni Y, Zhang H, Chai C, Peng B, Zhao A, Zhang J, Li L, Zhang C, Ma B, Bai H, Lim KL, Huang W

Adv Healthc Mater. 2019 Jul;8(14):e1900212. doi: 10.1002/adhm.201900212. Epub 2019 May 13.

Abstract

Organelle-targeted photosensitizers have been reported to be effective cell apoptosis agents. Mitochondria is recognized as an ideal target for cancer treatment due to its central role in oxidative metabolism and apoptosis. Meanwhile, two-photon (TP) fluorescence microscopy has become a powerful tool for fluorescence imaging in biological events based on its minimizing photodamage/photobleaching and intrinsic 3D resolution in deep tissues and in vivo. In this study, a series of novel mitochondrial-targeted TP fluorescent photosensitizers (TP-tracers) are designed, synthesized, and systematically investigated. These TP-tracers exhibit extraordinary anti-interference capability among different cations, anions, and amino acids as well as the insensitivity to the changes of pH and complex biological environments. TP-tracers are further used in fluorescence living cells, Drosophila brains, and zebrafish imaging with low cytotoxicity, excellent mitochondria-targeting, and TP properties. The results demonstrate efficient mitochondria-targeting cell selective apoptosis based on TP-activated cancer cells with highly single cell selectivity, and the pharmacokinetic study reveals that MitoY2 does not have accumulation in rats. It is believed that these molecules hold great potential in TP-related smart phototherapy.

Visualization of Intra-neuronal Motor Protein Transport through Upconversion Microscopy.

Zeng X, Chen S, Weitemier A, Han S, Blasiak A, Prasad A, Zheng K, Yi Z, Luo B, Yang IH, Thakor N, Chai C, Lim KL, McHugh TJ, All AH, Liu X.

Angewandte Chemie International Edition. 2019 Jul 1;58(27):9262-9268. doi: 10.1002/anie.201904208. Epub 2019 May 28.

Abstract

Cargo transport along axons, a physiological process mediated by motor proteins, is essential for neuronal function and survival. A current limitation in the study of axonal transport is the lack of a robust imaging technique with a high spatiotemporal resolution to visualize and quantify the movement of motor proteins in real-time and in different depth planes. Herein, we present a dynamic imaging technique that fully exploits the characteristics of upconversion nanoparticles. This technique can be used as a microscopic probe for the quantitative in situ tracking of retrograde transport neurons with single-particle resolution in multilayered cultures. This study may provide a powerful tool to reveal dynamic neuronal activity and intra-axonal transport function as well as any associated neurodegenerative diseases resulting from mutation or impairment in the axonal transport machinery.

Cell signaling and fate through the redox lens.

Pervaiz S.

Redox Biology. 2019 Aug 9:101298. doi: 10.1016/j.redox.2019.101298. [Epub ahead of print].

Abstract

A novel scoring system for pivotal autophagy-related genes predicts outcomes after chemotherapy in advanced ovarian cancer patients.

Niu Y, Sun W, Chen K, Fu Z, Chen Y, Zhu J, Chen H, Shi Y, Zhang H, Wang L, Shen HM, Xia D, Wu Y.

Cancer Epidemiology, Biomarkers & Prevention. 2019 Sep 18. pii: cebp.0359.2019. doi: 10.1158/1055-9965.EPI-19-0359. [Epub ahead of print]

Abstract

BACKGROUND:
In the clinical practice of ovarian cancer, the application of autophagy, an important regulator of carcinogenesis and chemoresistance, is still limited. This study aimed to establish a scoring system based on expression profiles of pivotal autophagy-related (ATG) genes in stage III/IV ovarian cancer patients who received chemotherapy.
METHODS:
Data of ovarian serous cystadenocarcinoma in The Cancer Genome Atlas (TCGA-OV) were used as training dataset. Two validation datasets comprised patients in a Chinese local database and a dataset from the Gene Expression Omnibus (GEO). ATG genes significantly (P < 0.1) associated with overall survival (OS) were selected and aggregated into an ATG scoring scale, of which the abilities to predict OS and recurrence-free survival (RFS) were examined.
RESULTS:
43 autophagy-related genes were selected to develop the ATG score. In TCGA-OV, patients with lower ATG scores had better OS [hazard ratio, 0.41; 95% confidence interval (CI), 0.26-0.65; P < 0.001) and RFS (hazard ratio, 0.47; 95% CI, 0.27-0.82; P = 0.007). After complete or partial remission to primary therapy, the rate of recurrence was 47.2% in the low-score group and 68.3% in the high-score group (odds ratio, 0.42; 95% CI, 0.18-0.92; P = 0.03). Such findings were verified in the two validation datasets.
CONCLUSION:
We established a novel scoring system based on pivotal ATG genes, which accurately predicts the outcomes of advanced ovarian cancer patients after chemotherapy.
IMPACT:
The present ATG scoring system may provide a novel perspective and a promising tool for the development of personalized therapy in the future.

Targeted metabolomics reveals differential biological effects of nanoplastics and nanoZnO in human lung cells.

Lim SL, Ng CT, Zou L, Lu Y, Chen J, Bay BH, Shen HM, Ong CN.

Nanotoxicology. 2019 Oct;13(8):1117-1132. doi: 10.1080/17435390.2019.1640913. Epub 2019 Jul 24.

Abstract

Engineered nanomaterials are of public health concern. Recently, there has been an increasing attention on the toxicity of nanoplastics and nanoZnO because of their increasing utilization and presence in the environment. However, knowledge of their toxicological behavior and metabolic interactions with the cellular machinery that determine their potential health effects are extremely limited. In this study, the cellular uptake, cytotoxic effects, and metabolic responses of bronchus epithelial (BEAS-2B) cells exposed to nanopolystyrene (nanoPS) and a widely used metallic nanoparticle, nanoZnO, were investigated using a tandem mass spectrometry-based metabolomics approach. The results revealed that even with low cytotoxicity, these nanoparticles (NPs) affected cell metabolism. NanoPS exposure showed autophagic- and endoplasmic reticulum (ER) stress-related metabolic changes such as increased in amino acids and tricarboxylic acid cycle (TCA) intermediate metabolites, a process known to play a critical role in regulating cell resistance to cytotoxic effects. Both metabolomics profiling and ER-stress pathway, together with quantitative real-time RT-polymerase chain reaction (qRT-PCR) analyses, demonstrated that autophagy was reciprocally regulated to couple metabolic and transcriptional reprograming. In contrast, nanoZnO-induced ROS-mediated cell death was associated with mitochondrial dysfunction and interference in regulating energy metabolism. Collectively, these two types of NPs were observed to cause perturbations albeit differential in cellular metabolism associated with their cytotoxic effects. Our findings provided an in depth understanding of metabolic changes influenced by two different types of NPs, with contrasting molecular mechanisms for the adverse effects observed.

STX17 dynamically regulated by Fis1 induces mitophagy via hierarchical macroautophagic mechanism.

Xian H, Yang Q, Xiao L, Shen HM, Liou YC.

Nature Communications. 2019 May 3;10(1):2059. doi: 10.1038/s41467-019-10096-1.

Abstract

Mitophagy is the selective autophagic targeting and removal of dysfunctional mitochondria. While PINK1/Parkin-dependent mitophagy is well-characterized, PINK1/Parkin-independent route is poorly understood. Using structure illumination microscopy (SR-SIM), we demonstrate that the SNARE protein Syntaxin 17 (STX17) initiates mitophagy upon depletion of outer mitochondrial membrane protein Fis1. With proteomics analysis, we identify the STX17-Fis1 interaction, which controls the dynamic shuffling of STX17 between ER and mitochondria. Fis1 loss results in aberrant STX17 accumulation on mitochondria, which exposes the N terminus and promotes self-oligomerization to trigger mitophagy. Mitochondrial STX17 interacts with ATG14 and recruits core autophagy proteins to form mitophagosome, followed by Rab7-dependent mitophagosome-lysosome fusion. Furthermore, Fis1 loss impairs mitochondrial respiration and potentially sensitizes cells to mitochondrial clearance, which is mediated through canonical autophagy machinery, closely linking non-selective macroautophagy to mitochondrial turnover. Our findings uncover a PINK1/Parkin-independent mitophagic mechanism in which outer mitochondrial membrane protein Fis1 regulates mitochondrial quality control.

Lysosomal inhibition attenuates peroxisomal gene transcription via suppression of PPARA and PPARGC1A levels.

Siong Tan HW, Anjum B, Shen HM, Ghosh S, Yen PM, Sinha RA.

Autophagy. 2019 Aug;15(8):1455-1459. doi: 10.1080/15548627.2019.1609847. Epub 2019 Apr 28.

Abstract

Lysosomes influence dynamic cellular processes such as nutrient sensing and transcriptional regulation. To explore novel transcriptional pathways regulated by lysosomes, we performed microarray analysis followed by qPCR validation in a mouse hepatocyte cell line, AML12, treated with bafilomycin A1 (lysosomal v-type H+-translocating ATPase inhibitor). Pathway enrichment analysis revealed significant downregulation of gene sets related to peroxisomal biogenesis and peroxisomal lipid oxidation upon lysosomal inhibition. Mechanistically, pharmacological inhibition of lysosomes as well as genetic knockdown of Tfeb led to downregulation of the peroxisomal master regulator PPARA and its coactivator PPARGC1A/PGC1α. Consistently, ectopic induction of PPARA transcriptional activity rescues the effects of lysosomal inhibition on peroxisomal gene expression. Collectively, our results uncover a novel metabolic regulation of peroxisomes by lysosomes via PPARA-PPARGC1A transcriptional signalling. Abbreviations: Acox1: acyl-Coenzyme A oxidase 1, palmitoyl; Acot: acyl-CoA thioesterase; ACAA: acetyl-Coenzyme A acyltransferase; ABCD3/PMP70: ATP-binding cassette, sub-family D (ALD), member 3; BafA1: bafilomycin A1; Crot: carnitine O-octanoyltransferase; CTSB: cathepsin B; Decr2: 2-4-dienoyl-Coenzyme A reductase 2, peroxisomal; Ech1: enoyl coenzyme A hydratase 1, peroxisomal; Ehhadh: enoyl-Coenzyme A, hydratase/3-hydroxyacyl Coenzyme A dehydrogenase; FDR: false discovery rate; Hsd17b4: hydroxysteroid (17-beta) dehydrogenase 4; NES: normalized enrichment score; NOM: nominal; Pex: peroxin; PPARA: peroxisome proliferator activated receptor alpha; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; TFEB: transcription factor EB.

Manipulating energy migration within single lanthanide activator for switchable upconversion emissions towards bidirectional photoactivation.

Mei Q, Bansal A, Jayakumar MKG, Zhang Z, Zhang J, Huang H, Yu D, Ramachandra CJA, Hausenloy DJ, Soong TW, Zhang Y.

Nature Communications. 2019 Sep 27;10(1):4416. doi: 10.1038/s41467-019-12374-4.

Abstract

Intravenous Immunoglobulin (IVIg) Induce a Protective Phenotype in Microglia Preventing Neuronal Cell Death in Ischaemic Stroke.

Häußler V, Daehn T, Rissiek B, Roth V, Gerloff C, Arumugam TV, Magnus T, Gelderblom M.

Neuromolecular Medicine. 2019 Sep 26. doi: 10.1007/s12017-019-08571-5. [Epub ahead of print]

Abstract

Targeting the immune system and thereby modulating the inflammatory response in ischemic stroke has shown promising therapeutic potential in various preclinical trials. Among those, intravenous immunoglobulins (IVIg) have moved into the focus of attention. In a murine model of experimental stroke, we explored the therapeutic potential of IVIg on the neurological outcome and the inflammatory response. Further, we used an in vitro system to assess effects of IVIg-stimulated microglia on neuronal survival. Treatment with IVIg resulted in decreased lesion sizes, without significant effects on the infiltration and activation pattern of peripheral immune cells. However, in microglia IVIg induced a switch towards an upregulation of protective polarization markers, and the ablation of microglia led to the loss of neuroprotective IVIg effects. Functionally, IVIg stimulated microglia ameliorated neuronal cell death elicited by oxygen and glucose deprivation in vitro. Notably, application of IVIg in vivo led to a comparable decrease of apoptotic neurons in the penumbra area. Although neuroprotective effects of IVIg in vivo and in vitro have been established in previous studies, we were able to show for the first time, that IVIg modulates the polarization of microglia during the pathogenesis of stroke.

Peptidase neurolysin functions to preserve the brain after ischemic stroke in male mice.

Jayaraman S, Al Shoyaib A, Kocot J, Villalba H, Alamri FF, Rashid M, Wangler NJ, Chowdhury EA, German N, Arumugam TV, Abbruscato TJ, Karamyan VT.

Journal of Neurochemistry. 2019 Sep 5. doi: 10.1111/jnc.14864. [Epub ahead of print]

Abstract

Previous studies documented upregulation of peptidase neurolysin (Nln) after brain ischemia, however the significance of Nln function in the post-stroke brain remained unknown. The aim of this study was to assess the functional role of Nln in the brain after ischemic stroke. Administration of a specific Nln inhibitor Agaricoglyceride A (AgaA) to mice after stroke in a middle cerebral artery occlusion model (MCAO), dose-dependently aggravated injury measured by increased infarct and edema volumes, blood-brain barrier disruption, increased levels of IL-6 and MCP-1, neurological and motor deficit 24 h after stroke. In this setting, AgaA resulted in inhibition of Nln in the ischemic hemisphere leading to increased levels of Nln substrates bradykinin, neurotensin and substance P. AgaA lacked effects on several physiological parameters and appeared non-toxic to mice. In a reverse approach, we developed an adeno-associated viral vector (AAV2/5-CAG-Nln) to overexpress Nln in the mouse brain. Applicability of AAV2/5-CAG-Nln to transduce catalytically active Nln was confirmed in primary neurons and in vivo. Overexpression of Nln in the mouse brain was also accompanied by decreased levels of its substrates. Two weeks after in vivo transduction of Nln using the AAV vector, mice were subjected to MCAO and the same outcome measures were evaluated 72 h later. These experiments revealed that abundance of Nln in the brain protects animals from stroke. This study is the first to document functional significance of Nln in pathophysiology of stroke and provide evidence that Nln is an endogenous mechanism functioning to preserve the brain from ischemic injury.

Effect of fingolimod on oligodendrocyte maturation under prolonged cerebral hypoperfusion.

Yasuda K, Maki T, Saito S, Yamamoto Y, Kinoshita H, Choi YK, Arumugam TV, Lim YA, Chen CLH, Wong PT, Ihara M, Takahashi R.

Brain Research. 2019 Oct 1;1720:146294. doi: 10.1016/j.brainres.2019.06.013. Epub 2019 Jun 12.

Abstract

Oligodendrocytes (OLGs) support neuronal system and have crucial roles for brain homeostasis. As the renewal and regeneration of OLGs derived from oligodendrocyte precursor cells (OPCs) are inhibited by various pathological conditions, the restoration of impaired oligodendrogenesis is a therapeutic strategy for OLG-related diseases such as subcortical ischemic vascular dementia (SIVD). Fingolimod (FTY720), a drug for multiple sclerosis, is reported to elicit a cytoprotective effect on OPCs in vitro. However, the effects of fingolimod against ischemia-induced suppression of OPC differentiation remain unknown. Hence, the purpose of this study was to investigate the effectiveness of fingolimod against ischemia-induced suppression of oligodendrogenesis. For the in vitro experiments, primary rat cultured OPCs were incubated with a non-lethal concentration of CoCl2 to induce chemical hypoxic conditions and were treated with or without fingolimod-phosphate. We found that low concentration fingolimod-phosphate directly rescued ischemia-induced suppression of OPC differentiation via the phosphoinositide 3-kinase-Akt pathway. For the in vivo experiments, we used a mouse model of SIVD generated by bilateral common carotid artery stenosis. On day 28 after surgery, fingolimod ameliorated ischemia-induced demyelination and promoted oligodendrogenesis under prolonged cerebral hypoperfusion. The present study demonstrates that fingolimod can promote oligodendrogenesis under ischemic conditions and may be a therapeutic candidate for SIVD.

The Transcription Factor Bhlhe40 Programs Mitochondrial Regulation of Resident CD8+ T Cell Fitness and Functionality.

Li C, Zhu B, Son YM, Wang Z, Jiang L, Xiang M, Ye Z, Beckermann KE, Wu Y, Jenkins JW, Siska PJ, Vincent BG, Prakash YS, Peikert T, Edelson BT, Taneja R, Kaplan MH, Rathmell JC, Dong H, Hitosugi T, Sun J.

Immunity. 2019 Sep 17;51(3):491-507.e7. doi: 10.1016/j.immuni.2019.08.013.

Abstract

Tissue-resident memory CD8+ T (Trm) cells share core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic, and epigenetic regulation of Trm cell and TIL development and function is largely undefined. Here, we found that the transcription factor Bhlhe40 was specifically required for Trm cell and TIL development and polyfunctionality. Local PD-1 signaling inhibited TIL Bhlhe40 expression, and Bhlhe40 was critical for TIL reinvigoration following anti-PD-L1 blockade. Mechanistically, Bhlhe40 sustained Trm cell and TIL mitochondrial fitness and a functional epigenetic state. Building on these findings, we identified an epigenetic and metabolic regimen that promoted Trm cell and TIL gene signatures associated with tissue residency and polyfunctionality. This regimen empowered the anti-tumor activity of CD8+ T cells and possessed therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights into the local regulation of Trm cell and TIL function.

Ambient and supplemental magnetic fields promote myogenesis via a TRPC1-mitochondrial axis: evidence of a magnetic mitohormetic mechanism.

Yap JLY, Tai YK, Fröhlich J, Fong CHH, Yin JN, Foo ZL, Ramanan S, Beyer C, Toh SJ, Casarosa M, Bharathy N, Kala MP, Egli M, Taneja R, Lee CN, Franco-Obregón A.

FASEB Journal. 2019 Sep 13:fj201900057R. doi: 10.1096/fj.201900057R. [Epub ahead of print]

Abstract

We show that both supplemental and ambient magnetic fields modulate myogenesis. A lone 10 min exposure of myoblasts to 1.5 mT amplitude supplemental pulsed magnetic fields (PEMFs) accentuated in vitro myogenesis by stimulating transient receptor potential (TRP)-C1-mediated calcium entry and downstream nuclear factor of activated T cells (NFAT)-transcriptional and P300/CBP-associated factor (PCAF)-epigenetic cascades, whereas depriving myoblasts of ambient magnetic fields slowed myogenesis, reduced TRPC1 expression, and silenced NFAT-transcriptional and PCAF-epigenetic cascades. The expression levels of peroxisome proliferator-activated receptor γ coactivator 1α, the master regulator of mitochondriogenesis, was also enhanced by brief PEMF exposure. Accordingly, mitochondriogenesis and respiratory capacity were both enhanced with PEMF exposure, paralleling TRPC1 expression and pharmacological sensitivity. Clustered regularly interspaced short palindromic repeats-Cas9 knockdown of TRPC1 precluded proliferative and mitochondrial responses to supplemental PEMFs, whereas small interfering RNA gene silencing of TRPM7 did not, coinciding with data that magnetoreception did not coincide with the expression or function of other TRP channels. The aminoglycoside antibiotics antagonized and down-regulated TRPC1 expression and, when applied concomitantly with PEMF exposure, attenuated PEMF-stimulated calcium entry, mitochondrial respiration, proliferation, differentiation, and epigenetic directive in myoblasts, elucidating why the developmental potential of magnetic fields may have previously escaped detection. Mitochondrial-based survival adaptations were also activated upon PEMF stimulation. Magnetism thus deploys an authentic myogenic directive that relies on an interplay between mitochondria and TRPC1 to reach fruition.-Yap, J. L. Y., Tai, Y. K., Fröhlich, J., Fong, C. H. H., Yin, J. N., Foo, Z. L., Ramanan, S., Beyer, C., Toh, S. J., Casarosa, M., Bharathy, N., Kala, M. P., Egli, M., Taneja, R., Lee, C. N., Franco-Obregón, A. Ambient and supplemental magnetic fields promote myogenesis via a TRPC1-mitochondrial axis: evidence of a magnetic mitohormetic mechanism.

Integrin α7 expression is increased in asthmatic patients and its inhibition reduces Kras protein abundance in airway smooth muscle cells.

Teoh CM, Tan SSL, Langenbach SY, Wong AH, Cheong DHJ, Tam JKC, New CS, Tran T.

Scientific Reports. 2019 Jul 9;9(1):9892. doi: 10.1038/s41598-019-46260-2.

Abstract

Airway smooth muscle (ASM) cells exhibit plastic phenotypic behavior marked by reversible modulation and maturation between contractile and proliferative phenotypic states. Integrins are a class of transmembrane proteins that have been implicated as novel therapeutic targets for asthma treatment. We previously showed that integrin α7 is a novel marker of the contractile ASM phenotype suggesting that targeting this protein may offer new avenues to counter the increase in ASM cell mass that underlies airways hyperresponsiveness (AHR) in asthma. We now determine whether inhibition of integrin α7 expression would revert ASM cells back to a proliferative phenotype to cause an increase in ASM cell mass. This would be detrimental to asthmatic patients who already exhibit increased ASM mass in their airways. Using immunohistochemical analysis of the Melbourne Epidemiological Study of Childhood Asthma (MESCA) cohort, we show for the first time that integrin α7 expression in patients with severe asthma is increased, supporting a clinically relevant role for this protein in asthma pathophysiology. Moreover, inhibition of the laminin-integrin α7 signaling axis results in a reduction in smooth muscle-alpha actin abundance and does not revert ASM cells back to a proliferative phenotype. We determined that integrin α7-induced Kras isoform of p21 Ras acts as a point of convergence between contractile and proliferative ASM phenotypic states. Our study provides further support for targeting integrin α7 for the development of novel anti-asthma therapies.

Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems.

Tavakol S, Ashrafizadeh M, Deng S, Azarian M, Abdoli A, Motavaf M, Poormoghadam D, Khanbabaei H, Afshar EG, Mandegary A, Pardakhty A, Yap CT, Mohammadinejad R, Kumar AP.

Biomolecules. 2019 Sep 25;9(10). pii: E530. doi: 10.3390/biom9100530.

Abstract

FUS-mediated dysregulation of Sema5a, an autism-related gene, in FUS mice with hippocampus-dependent cognitive deficits.

Ho WY, Chang JC, Tyan SH, Yen YC, Lim K, Tan BSY, Ong J, Tucker-Kellogg G, Wong P, Koo E, Ling SC.

Human Molecular Genetics. 2019 Sep 11. pii: ddz217. doi: 10.1093/hmg/ddz217. [Epub ahead of print]

Abstract

Pathological FUS inclusions are found in 10% of patients with frontotemporal dementia (FTD) and those with amyotrophic lateral sclerosis (ALS) carrying FUS mutations. Current work indicates that FUS mutations may incur gain-of-toxic functions to drive ALS pathogenesis. However, how FUS dysfunction may affect cognition remains elusive. Using a mouse model expressing wild-type human FUS mimicking the endogenous expression pattern and level within the central nervous system, we found that they developed hippocampus-mediated cognitive deficits accompanied by an age-dependent reduction in spine density and long-term potentiation (LTP) in their hippocampus. However, there were no apparent FUS aggregates, nuclear envelope defects and cytosolic FUS accumulation. These suggest that these proposed pathogenic mechanisms may not be the underlying causes for the observed cognitive deficits. Unbiased transcriptomic analysis identified expression changes in a small set of genes with preferential expression in the neurons and oligodendrocyte lineage cells. Of these, we focused on Sema5a, a gene involved in axon guidance, spine dynamics, Parkinson's disease and autism spectrum disorders. Critically, FUS binds directly to Sema5a mRNA and regulates Sema5a expression in a FUS-dose-dependent manner. Taken together, our data suggest that FUS-driven Sema5a deregulation may underlie the cognitive deficits in FUS transgenic mice.

C9orf72 intermediate repeats are associated with corticobasal degeneration, increased C9orf72 expression and disruption of autophagy.

Cali CP, Patino M, Tai YK, Ho WY, McLean CA, Morris CM, Seeley WW, Miller BL, Gaig C, Vonsattel JPG, White CL, Roeber S, Kretzschmar H, Troncoso JC, Troakes C, Gearing M, Ghetti B, Van Deerlin VM, Lee VM, Trojanowski JQ, Mok KY, Ling H, Dickson DW, Schellenberg GD, Ling SC, Lee EB.

Acta Neuropathologica. 2019 Jul 20. doi: 10.1007/s00401-019-02045-5. [Epub ahead of print]

Abstract

Microsatellite repeat expansion disease loci can exhibit pleiotropic clinical and biological effects depending on repeat length. Large expansions in C9orf72 (100s-1000s of units) are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). However, whether intermediate expansions also contribute to neurodegenerative disease is not well understood. Several studies have identified intermediate repeats in Parkinson's disease patients, but the association was not found in autopsy-confirmed cases. We hypothesized that intermediate C9orf72 repeats are a genetic risk factor for corticobasal degeneration (CBD), a neurodegenerative disease that can be clinically similar to Parkinson's but has distinct tau protein pathology. Indeed, intermediate C9orf72 repeats were significantly enriched in autopsy-proven CBD (n = 354 cases, odds ratio = 3.59, p = 0.00024). While large C9orf72 repeat expansions are known to decrease C9orf72 expression, intermediate C9orf72 repeats result in increased C9orf72 expression in human brain tissue and CRISPR/cas9 knockin iPSC-derived neural progenitor cells. In contrast to cases of FTD/ALS with large C9orf72 expansions, CBD with intermediate C9orf72 repeats was not associated with pathologic RNA foci or dipeptide repeat protein aggregates. Knock-in cells with intermediate repeats exhibit numerous changes in gene expression pathways relating to vesicle trafficking and autophagy. Additionally, overexpression of C9orf72 without the repeat expansion leads to defects in autophagy under nutrient starvation conditions. These results raise the possibility that therapeutic strategies to reduce C9orf72 expression may be beneficial for the treatment of CBD.

Elevated FUS levels by overriding its autoregulation produce gain-of-toxicity properties that disrupt protein and RNA homeostasis.

Ho WY, Ling SC.

Autophagy. 2019 Sep;15(9):1665-1667. doi: 10.1080/15548627.2019.1633162. Epub 2019 Jun 23.

Abstract

Coding or non-coding mutations in FUS (fused in sarcoma) cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In addition to familial ALS, abnormal aggregates of FUS are present in a portion of FTD and other neurodegenerative diseases independent of their mutations. Broad expression within the central nervous system of either wild-type or two ALS-linked human FUS mutants produces progressive motor phenotypes accompanied by characteristic ALS-like pathology. FUS levels are autoregulated to maintain an optimal steady-state level. Increasing FUS expression by saturating its autoregulatory mechanism results in rapidly progressive neurological phenotypes and dose-dependent lethality. Genome-wide expression analysis reveals genetic mis-regulations distinct from those via FUS reduction. Among these are increased expression of lysosomal proteins, suggestive of disruption in protein homeostasis as a potential gain-of-toxicity mechanism. Indeed, increased expression of wild-type FUS or ALS-linked mutant forms of FUS inhibit macroautophagy/autophagy. Collectively, our results demonstrate that: (1) mice expressing FUS develop progressive motor deficits, (2) increased FUS expression by overriding its autoregulatory mechanism accelerates neurodegeneration, providing a basis for FUS involvement without mutation, and (3) disruption in both protein homeostasis and RNA processing contribute to FUS-mediated toxicity.

Increased expression of heme-binding protein 1 early in Alzheimer's disease is linked to neurotoxicity

Yagensky O, Kohansal-Nodehi M, Gunaseelan S, Rabe T, Zafar S, Zerr I, Haertig W, Urlaub H, Chua JJE

eLife. 2019 Aug 27;8:e47498. doi: 10.7554/eLife.47498.

Abstract

Alzheimer's disease is the most prevalent neurodegenerative disorder leading to progressive cognitive decline. Despite decades of research, understanding AD progression at the molecular level, especially at its early stages, remains elusive. Here, we identified several presymptomatic AD markers by investigating brain proteome changes over the course of neurodegeneration in a transgenic mouse model of AD (3×Tg-AD). We show that one of these markers, heme-binding protein 1 (Hebp1), is elevated in the brains of both 3×Tg-AD mice and patients affected by rapidly-progressing forms of AD. Hebp1, predominantly expressed in neurons, interacts with the mitochondrial contact site complex (MICOS) and exhibits a perimitochondrial localization. Strikingly, wildtype, but not Hebp1-deficient, neurons showed elevated cytotoxicity in response to heme-induced apoptosis. Increased survivability in Hebp1-deficient neurons is conferred by blocking the activation of the mitochondrial-associated caspase signaling pathway. Taken together, our data highlight a role of Hebp1 in progressive neuronal loss during AD progression.

A feedforward relationship between active Rac1 and phosphorylated Bcl-2 is critical for sustaining Bcl-2 phosphorylation and promoting cancer progression

Chong SJF, Lai JXH, Qu J, Hirpara J, Kang J, Swaminathan K, Loh T, Kumar A, Vali S, Abbasi T, Pervaiz S.

Cancer Lett. 2019 Aug 10;457:151-167. DOI: 10.1016/j.canlet.2019.05.009.

Abstract

Active GTPase-Rac1 is associated with cellular processes involved in carcinogenesis and expression of Bcl-2 endows cells with the ability to evade apoptosis. Here we provide evidence that active Rac1 and Bcl-2 work in a positive feedforward loop to promote sustained phosphorylation of Bcl-2 at serine-70 (S70pBcl-2), which stabilizes its anti-apoptotic activity. Pharmacological and genetic inactivation of Rac1 prevent interaction with Bcl-2 and reduce S70pBcl-2. Similarly, BH3-mimetic inhibitors of Bcl-2 could disrupt Rac1-Bcl-2 interaction and reduce S70pBcl-2. This effect of active Rac1 could also be rescued by scavengers of intracellular superoxide (O2.−), thus implicating NOX-activating activity of Rac1 in promoting S70pBcl-2. Moreover, active Rac1-mediated redox-dependent S70pBcl-2 involves the inhibition of phosphatase PP2A holoenzyme assembly. Sustained S70pBcl-2 in turn secures Rac1/Bcl-2 interaction. Importantly, inhibiting Rac1 activity, scavenging O2.− or employing BH3-mimetic inhibitor significantly reduced S70pBcl-2-mediated survival in cancer cells. Notably, Rac1 expression, and its interaction with Bcl-2, positively correlate with S70pBcl-2 levels in patient-derived lymphoma tissues and with advanced stage lymphoma and melanoma. Together, we provide evidence of a positive feedforward loop involving active Rac1, S70pBcl-2 and PP2A, which could have potential diagnostic, prognostic and therapeutic implications.

Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.

Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.

Biomaterials. 2019 May;201:16-32. DOI: 10.1016/j.biomaterials.2019.01.046. Epub 2019 Feb 6.

Abstract

NRF2/ARE pathway negatively regulates BACE1 expression and ameliorates cognitive deficits in mouse Alzheimer's models.

Bahn G, Park JS, Yun UJ, Lee YJ, Choi Y, Park JS, Baek SH, Choi BY, Cho YS, Kim HK, Han J, Sul JH, Baik SH, Lim J, Wakabayashi N, Bae SH, Han JW, Arumugam TV, Mattson MP, Jo DG.

Proc Natl Acad Sci U S A. 2019 Jun 18;116(25):12516-12523. DOI: 10.1073/pnas.1819541116. Epub 2019 Jun 4.

Abstract

BACE1 is the rate-limiting enzyme for amyloid-β peptides (Aβ) generation, a key event in the pathogenesis of Alzheimer's disease (AD). By an unknown mechanism, levels of BACE1 and a BACE1 mRNA-stabilizing antisense RNA (BACE1-AS) are elevated in the brains of AD patients, implicating that dysregulation of BACE1 expression plays an important role in AD pathogenesis. We found that nuclear factor erythroid-derived 2-related factor 2 (NRF2/NFE2L2) represses the expression of BACE1 and BACE1-AS through binding to antioxidant response elements (AREs) in their promoters of mouse and human. NRF2-mediated inhibition of BACE1 and BACE1-AS expression is independent of redox regulation. NRF2 activation decreases production of BACE1 and BACE1-AS transcripts and Aβ production and ameliorates cognitive deficits in animal models of AD. Depletion of NRF2 increases BACE1 and BACE1-AS expression and Aβ production and worsens cognitive deficits. Our findings suggest that activation of NRF2 can prevent a key early pathogenic process in AD.e in humans and IL-37tg mice, and may exert protective effects by modulating post-stroke inflammation in the brain and periphery.

IL-37 increases in patients after ischemic stroke and protects from inflammatory brain injury, motor impairment and lung infection in mice.

Zhang SR, Nold MF, Tang SC, Bui CB, Nold CA, Arumugam TV, Drummond GR, Sobey CG, Kim HA.

Sci Rep. 2019 May 6;9(1):6922.DOI: 10.1038/s41598-019-43364-7.

Abstract

Post-stroke inflammation may contribute to secondary brain injury and systemic immunosuppression. Interleukin(IL)-37 is an immunosuppressive cytokine belonging to the IL-1 superfamily with no mouse homologue yet identified, the effects of which have not been studied in stroke. Here we report: (1) the effect of ischemic stroke on circulating IL-37 in humans; and (2) the effect of IL-37 on stroke outcome measures in mice transgenic for human IL-37 (IL-37tg). We found that in the first 3 days after ischemic stroke in 55 patients, the plasma abundance of IL-37 was ~2-fold higher than in 24 controls. In IL-37tg mice, cerebral ischemia-reperfusion resulted in marked increases in plasma IL-37 (~9-fold) and brain IL-37 mRNA (~7,000-fold) at 24 h compared with sham-operated IL-37tg mice. Further, compared with wild-type (WT) mice subjected to cerebral ischemia-reperfusion, IL-37tg mice exhibited less severe locomotor deficit, smaller cerebral infarcts and reduced bacterial lung infection. In the ischemic hemisphere, there were 60% fewer pro-inflammatory microglia-macrophages and up to 4-fold higher expression of anti-inflammatory markers in IL-37tg compared to WT mice. Our data show that IL-37 expression is increased following ischemic stroke in humans and IL-37tg mice, and may exert protective effects by modulating post-stroke inflammation in the brain and periphery.

Cerebral transcriptome analysis reveals age-dependent progression of neuroinflammation in P301S mutant tau transgenic male mice.

Kim J, Selvaraji S, Kang SW, Lee WT, Chen CL, Choi H, Koo EH, Jo DG, Leong Lim K, Lim YA, Arumugam TV.

Brain Behav Immun. 2019 Apr 11. pii: S0889-1591(18)30842-0. DOI: 10.1016/j.bbi.2019.04.011. [Epub ahead of print]

Abstract

Aggregation of the microtubule-associated protein, tau, can lead to neurofibrillary tangle formation in neurons and glia which is the hallmark of tauopathy. The cellular damage induced by the formation of neurofibrillary tangles leads to neuroinflammation and consecutive neuronal death. However, detailed observation of transcriptomic changes under tauopathy together with the comparison of age-dependent progression of neuroinflammatory gene expressions mediated by tau overexpression is required. Employing RNA sequencing on PS19 transgenic mice that overexpress human mutant tau harboring the P301S mutation, we have examined the effects of age-dependent tau overexpression on transcriptomic changes of immune and inflammatory responses in the cerebral cortex. Compared to age-matched wild type control, P301S transgenic mice exhibit significant transcriptomic alterations. We have observed age-dependent neuroinflammatory gene expression changes in both wild type and P301S transgenic mice where tau overexpression further promoted the expression of neuroinflammatory genes in 10-month old P301S transgenic mice. Moreover, functional gene network analyses (gene ontology and pathway enrichment) and prospective target protein interactions predicted the potential involvement of multiple immune and inflammatory pathways that may contribute to tau-mediated neuronal pathology. Our current study on P301S transgenic mice model revealed for the first time, the differences of gene expression patterns in both early and late stage of tau pathology in cerebral cortex. Our analyses also revealed that tau overexpression alone induces multiple inflammatory and immune transcriptomic changes and may provide a roadmap to elucidate the targets of anti-inflammatory therapeutic strategy focused on tau pathology and related neurodegenerative diseases.

SynGO: An Evidence-Based, Expert-Curated Knowledge Base for the Synapse.

Koopmans F, van Nierop P, Andres-Alonso M, Byrnes A, Cijsouw T, Coba MP, Cornelisse LN, Farrell RJ, Goldschmidt HL, Howrigan DP, Hussain NK, Imig C, de Jong APH, Jung H, Kohansalnodehi M, Kramarz B, Lipstein N, Lovering RC, MacGillavry H, Mariano V, Mi H, Ninov M, Osumi-Sutherland D, Pielot R, Smalla KH, Tang H, Tashman K, Toonen RFG, Verpelli C, Reig-Viader R, Watanabe K, van Weering J, Achsel T, Ashrafi G8, Asi N, Brown TC, De Camilli P, Feuermann M, Foulger RE, Gaudet P, Joglekar A, Kanellopoulos A, Malenka R, Nicoll RA, Pulido C, de Juan-Sanz J, Sheng M, Südhof TC, Tilgner HU, Bagni C, Bayés À, Biederer T, Brose N, Chua JJE, Dieterich DC, Gundelfinger ED, Hoogenraad C, Huganir RL, Jahn R, Kaeser PS, Kim E, Kreutz MR, McPherson PS, Neale BM, O'Connor V, Posthuma D, Ryan TA, Sala C, Feng G, Hyman SE, Thomas PD, Smit AB, Verhage M.

Neuron. 2019 May 22. pii: S0896-6273(19)30427-1. DOI: 10.1016/j.neuron.2019.05.002. [Epub ahead of print]

Abstract

Synapses are fundamental information-processing units of the brain, and synaptic dysregulation is central to many brain disorders ("synaptopathies"). However, systematic annotation of synaptic genes and ontology of synaptic processes are currently lacking. We established SynGO, an interactive knowledge base that accumulates available research about synapse biology using Gene Ontology (GO) annotations to novel ontology terms: 87 synaptic locations and 179 synaptic processes. SynGO annotations are exclusively based on published, expert-curated evidence. Using 2,922 annotations for 1,112 genes, we show that synaptic genes are exceptionally well conserved and less tolerant to mutations than other genes. Many SynGO terms are significantly overrepresented among gene variations associated with intelligence, educational attainment, ADHD, autism, and bipolar disorder and among de novo variants associated with neurodevelopmental disorders, including schizophrenia. SynGO is a public, universal reference for synapse research and an online analysis platform for interpretation of large-scale -omics data (https://syngoportal.org and http://geneontology.org).

Increased Akt-Driven Glycolysis Is the Basis for the Higher Potency of CD137L-DCs.

Zeng Q, Mallilankaraman K, Schwarz H.

Front Immunol. 2019 Apr 24;10:868. DOI: 10.3389/fimmu.2019.00868. eCollection 2019.

Abstract

Epstein-Barr virus-encoded LMP1 induces ectopic CD137 expression on Hodgkin and Reed-Sternberg cells via the PI3K-AKT-mTOR pathway.

Priya Aravinth S, Rajendran S, Li Y, Wu M, Yi Wong AH, Schwarz H.

Leuk Lymphoma. 2019 May 6:1-8. DOI: 10.1080/10428194.2019.1607330. [Epub ahead of print]

Abstract

Induction of CD137 expression by viral genes reduces T cell costimulation.

Wu M, Wong HY, Lin JL, Moliner A, Schwarz H.

J Cell Physiol. 2019 Apr 25. DOI: 10.1002/jcp.28710.

Abstract

Intracellular pathogens are subject to elimination by a cellular immune response, and were therefore under evolutionary pressure to develop mechanisms that allow them to inhibit especially this arm of immunity. CD137, a T cell costimulatory molecule, and its ligand, CD137 ligand (CD137L), which is expressed on antigen presenting cells (APC), are potent drivers of cellular cytotoxic immune responses. Here, we report that different viruses usurp a negative feedback mechanism for the CD137-CD137L system that weakens cellular immune responses. Latent membrane protein (LMP)-1 and Tax, oncogenes of Epstein-Barr virus (EBV), and human T-cell lymphotropic virus (HTLV)-1, respectively, induce the expression of CD137. CD137 is transferred by trogocytosis to CD137L-expressing APC, and the CD137-CD137L complex is internalized and degraded, resulting in a reduced CD137-mediated T cell costimulation and a weakened cellular immune response which may facilitate the escape of the virus from immune surveillance. These data identify the usurpation of a CD137-based negative feedback mechanism by intracellular pathogens that enables them to reduce T cell costimulation.

Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis

Alhadad SB, Tan PMS, Lee JKW.

Front Physiol. 2019 Feb 13;10:71. DOI: 10.3389/fphys.2019.00071. eCollection 2019.

Abstract

Background: A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat, the rapid rise of body core temperature (T c ) often results in an impairment of exercise capacity and performance. As such, heat mitigation strategies such as aerobic fitness (AF), heat acclimation/acclimatization (HA), pre-exercise cooling (PC) and fluid ingestion (FI) can be introduced to counteract the debilitating effects of heat strain. We performed a meta-analysis to evaluate the effectiveness of these mitigation strategies using magnitude-based inferences. Methods: A computer-based literature search was performed up to 24 July 2018 using the electronic databases: PubMed, SPORTDiscus and Google Scholar. After applying a set of inclusion and exclusion criteria, a total of 118 studies were selected for evaluation. Each study was assessed according to the intervention's ability to lower T c before exercise, attenuate the rise of T c during exercise, extend T c at the end of exercise and improve endurance. Weighted averages of Hedges' g were calculated for each strategy. Results: PC (g = 1.01) was most effective in lowering T c before exercise, followed by HA (g = 0.72), AF (g = 0.65), and FI (g = 0.11). FI (g = 0.70) was most effective in attenuating the rate of rise of T c , followed by HA (g = 0.35), AF (g = -0.03) and PC (g = -0.46). In extending T c at the end of exercise, AF (g = 1.11) was most influential, followed by HA (g = -0.28), PC (g = -0.29) and FI (g = -0.50). In combination, AF (g = 0.45) was most effective at favorably altering Tc, followed by HA (g = 0.42), PC (g = 0.11) and FI (g = 0.09). AF (1.01) was also found to be most effective in improving endurance, followed by HA (0.19), FI (-0.16) and PC (-0.20). Conclusion: AF was found to be the most effective in terms of a strategy's ability to favorably alter T c , followed by HA, PC and lastly, FI. Interestingly, a similar ranking was observed in improving endurance, with AF being the most effective, followed by HA, FI, and PC. Knowledge gained from this meta-analysis will be useful in allowing athletes, coaches and sport scientists to make informed decisions when employing heat mitigation strategies during competitions in hot environments.<!--

The p75 neurotrophin receptor is an essential mediator of impairments in hippocampal-dependent associative plasticity and memory induced by sleep deprivation

Wong L, Tann JY, Ibáñez CF, Sajikumar S.

Journal of Neuroscience 13 May 2019, 2876-18; DOI: https://doi.org/10.1523/JNEUROSCI.2876-18.2019

Abstract

Sleep deprivation (SD) interferes with hippocampal structural and functional plasticity, formation of long-term memory (LTM) and cognitive function. The molecular mechanisms underlying these effects are incompletely understood. Here, we show that SD impaired synaptic tagging and capture (STC) and behavioral tagging (BT), two major mechanisms of associative learning and memory. Strikingly, mutant male mice lacking the p75 neurotrophin receptor (p75NTR) were resistant to the detrimental effects of SD on hippocampal plasticity at both cellular and behavioral levels. Mechanistically, SD increased p75NTR expression and its interaction with phosphodiesterase (PDE4A5). p75NTR deletion preserved hippocampal structural and functional plasticity by preventing SD-mediated effects on hippocampal cAMP-CREB-BDNF, cAMP-PKA-LIMK1-cofilin and RhoA-ROCK2 pathways. Our study identifies p75NTR as an important mediator of hippocampal structural and functional changes associated with SD, and suggests that targeting p75NTR could be a promising strategy to limit the memory and cognitive deficits that accompany sleep loss.

Altered Brain Structure with Preserved Cortical Motor Activity Following Exertional Hypohydration: A MRI

Tan XR, Low I, Stephenson MC, Kok T, Nolte HW, Soong TW, and Lee JKW.

Journal of Applied Physiology. 2019. doi: 10.1152/japplphysiol.00081.2019.

Abstract

Hypohydration exceeding 2% body mass can impair endurance capacity. It is postulated that the brain could be perturbed by hypohydration, leading to impaired motor performance. We investigated the neural effects of hypohydration using Magnetic Resonance Imaging (MRI). Ten males were dehydrated to ~ -3% body mass by running on a treadmill at 65% VO2max before either drinking to replace 100% (Euhydration; EU) or 0% (Hypohydration; HH) of fluid losses. MRI was performed prior to start of trial (baseline) and after rehydration phase (post) to evaluate brain structure, cerebral perfusion and functional activity. Endurance capacity assessed using a time-to-exhaustion run at 75% VO2max was reduced with hypohydration (EU: 45.2 ± 9.3 min, HH: 38.4 ± 10.7 min; p=0.033). Mean heart rates were comparable between trials (EU: 162 ± 5 bpm, HH: 162 ± 4 bpm, p=0.605) but the rate of rise in rectal temperature was higher in HH trials (EU: 0.06 ± 0.01°C·min-1, HH: 0.07 ± 0.02°C·min-1; p<0.01). In HH trials, a reduction in total brain volume (EU: +0.7 ± 0.6%, HH: -0.7 ± 0.9%) with expansion of ventricles (EU: -2.7 ± 1.6%, HH: +3.7 ± 3.3%) was observed, and vice versa in EU trials. Global and regional cerebral perfusion remained unchanged between conditions. Functional activation in the primary motor cortex (M1) in left hemisphere during a plantar-flexion task was similar between conditions (EU: +0.10 ± 1.30%, HH: -0.11 ± 0.31%; p=0.637). Our findings demonstrated that with exertional hypohydration, brain volumes were altered but the motor-related functional activity was unperturbed.

Epigenetics and memory: Emerging role of histone lysine methyltransferase G9a/GLP complex as bidirectional regulator of synaptic plasticity.

Pang KKL, Sharma M, Sajikumar S.

Neurobiol Learn Mem. 2019 Mar;159:1-5. doi: 10.1016/j.nlm.2019.01.013.

Abstract

Various epigenetic modifications, including histone lysine methylation, play an integral role in learning and memory. The importance of the histone lysine methyltransferase complex G9a/GLP and its associated histone H3 lysine K9 dimethylation in memory formation and cognition, has garnered the attention of researchers in the past decade. Recent studies feature G9a/GLP as the 'bidirectional regulator of synaptic plasticity', the neural correlate of memory. As the 'title' suggests, G9a/GLP participates in the maintenance of both long-term potentiation (LTP) and long-term depression (LTD). This complex is demonstrated to mostly suppress LTP-related plasticity-related products (PRPs). Notably, our recent paper also shows that G9a/GLP facilitates LTD maintenance in intact hippocampal slices - shedding light on the overlooked influence of epigenetics on LTD. Although the exact mechanisms of G9a/GLP activity regulation in cognition remain elusive, pharmacological inhibition of G9a/GLP presents a new avenue of therapeutic intervention in epigenetic dysfunction-related cognitive deficits.

Long-term population spike-timing-dependent plasticity promotes synaptic tagging but not cross-tagging in rat hippocampal area CA1.

Pang KKL, Sharma M, Krishna-K K, Behnisch T, Sajikumar S.

Proc Natl Acad Sci U S A. 2019 Mar 19;116(12):5737-5746. doi: 10.1073/pnas.1817643116.

Abstract

In spike-timing-dependent plasticity (STDP), the direction and degree of synaptic modification are determined by the coherence of pre- and postsynaptic activities within a neuron. However, in the adult rat hippocampus, it remains unclear whether STDP-like mechanisms in a neuronal population induce synaptic potentiation of a long duration. Thus, we asked whether the magnitude and maintenance of synaptic plasticity in a population of CA1 neurons differ as a function of the temporal order and interval between pre- and postsynaptic activities. Modulation of the relative timing of Schaffer collateral fibers (presynaptic component) and CA1 axons (postsynaptic component) stimulations resulted in an asymmetric population STDP (pSTDP). The resulting potentiation in response to 20 pairings at 1 Hz was largest in magnitude and most persistent (4 h) when presynaptic activity coincided with or preceded postsynaptic activity. Interestingly, when postsynaptic activation preceded presynaptic stimulation by 20 ms, an immediate increase in field excitatory postsynaptic potentials was observed, but it eventually transformed into a synaptic depression. Furthermore, pSTDP engaged in selective forms of late-associative activity: It facilitated the maintenance of tetanization-induced early long-term potentiation (LTP) in neighboring synapses but not early long-term depression, reflecting possible mechanistic differences with classical tetanization-induced LTP. The data demonstrate that a pairing of pre- and postsynaptic activities in a neuronal population can greatly reduce the required number of synaptic plasticity-evoking events and induce a potentiation of a degree and duration similar to that with repeated tetanization. Thus, pSTDP determines synaptic efficacy in the hippocampal CA3-CA1 circuit and could bias the CA1 neuronal population toward potentiation in future events.

Cleavable cellulosic sponge for functional hepatic cell culture and retrieval.

Sun M, Wong JY, Nugraha B, Ananthanarayanan A, Liu Z, Lee F, Gupta K, Fong ELS, Huang X, Yu H.

Biomaterials. 2019 May;201:16-32. doi: 10.1016/j.biomaterials.2019.01.046.

Abstract

Genetics, epigenetics and redox homeostasis in rhabdomyosarcoma: Emerging targets and therapeutics

Srinivasan S, Shankar SR, Wang Y, Taneja R.

Redox Biology. 2019 Jan 25. 101124. doi: 10.1016/j.redox.2019.101124.

Abstract

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma accounting for 5–8% of malignant tumours in children and adolescents. Children with high risk disease have poor prognosis. Anti-RMS therapies include surgery, radiation and combination chemotherapy. While these strategies improved survival rates, they have plateaued since 1990s as drugs that target differentiation and self-renewal of tumours cells have not been identified. Moreover, prevailing treatments are aggressive with drug resistance and metastasis causing failure of several treatment regimes. Significant advances have been made recently in understanding the genetic and epigenetic landscape in RMS. These studies have identified novel diagnostic and prognostic markers and opened new avenues for treatment. An important target identified in high throughput drug screening studies is reactive oxygen species (ROS). Indeed, many drugs in clinical trials for RMS impact tumour progression through ROS. In light of such emerging evidence, we discuss recent findings highlighting key pathways, epigenetic alterations and their impacts on ROS that form the basis of developing novel molecularly targeted therapies in RMS. Such targeted therapies in combination with conventional therapy could reduce adverse side effects in young survivors and lead to a decline in long-term morbidity.

SUMOylation of G9a regulates its function as an activator of myoblast proliferation

Srinivasan S, Shankar SR, Wang Y, Taneja R.

Cell Death and Disease. 2019. 10, Article number: 250. doi: 10.1038/s41419-019-1465-9.

Abstract

The lysine methyltransferase G9a plays a role in many cellular processes. It is a potent repressor of gene expression, a function attributed to its ability to methylate histone and non-histone proteins. Paradoxically, in some instances, G9a can activate gene expression. However, regulators of G9a expression and activity are poorly understood. In this study, we report that endogenous G9a is SUMOylated in proliferating skeletal myoblasts. There are four potential SUMOylation consensus motifs in G9a. Mutation of all four acceptor lysine residues [K79, K152, K256, and K799] inhibits SUMOylation. Interestingly, SUMOylation does not impact G9a-mediated repression of MyoD transcriptional activity or myogenic differentiation. In contrast, SUMO-defective G9a is unable to enhance proliferation of myoblasts. Using complementation experiments, we show that the proliferation defect of primary myoblasts from conditional G9a-deficient mice is rescued by re-expression of wild-type, but not SUMOylation-defective, G9a. Mechanistically, SUMOylation acts as signal for PCAF (P300/CBP-associated factor) recruitment at E2F1-target genes. This results in increased histone H3 lysine 9 acetylation marks at E2F1-target gene promoters that are required for S-phase progression. Our studies provide evidence by which SUMO modification of G9a influences the chromatin environment to impact cell cycle progression.

Bhlhe40 mediates tissue specific control of macrophage proliferation in homeostasis and type 2 immunity

Jarjour NN, Schwarzkopf EA, Bradstreet TR, Shchukina I, Lin CC, Huang SC, Lai CW, Cook ME, Taneja R, Stappenbeck T, Randolph GJ, Artymov MN, Urban JF, Edelson BT.

Nature Immunology. 2019, in press. doi:

Abstract

Epigenetic regulation of the PTEN-AKT-RAC1 axis by G9a is critical for tumor growth in alveolar rhabdomyosarcoma

Bhat AV, Palanichamy Kala M, Rao VK, Pignata L, Lim HJ, Suriyamurthy S, Chang KTE, Lee VK, Guccione E, Taneja R.

Cancer Research. 2019 in press. doi: 10.1158/0008-5472.CAN-18-2676.

Abstract

Alveolar Rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer with poor prognosis. As transient and stable modifications to chromatin have emerged as critical mechanisms in oncogenic signaling, efforts to target epigenetic modifiers as a therapeutic strategy have accelerated in recent years. To identify chromatin modifiers that sustain tumor growth, we performed an epigenetic screen and found that inhibition of lysine methyltransferase G9a significantly impacted the viability of ARMS cell lines. Targeting expression or activity of G9a reduced cellular proliferation and motility in vitro and tumor growth in vivo. Transcriptome and chromatin immunoprecipitation-sequencing analysis provided mechanistic evidence that the tumor suppressor PTEN was a direct target gene of G9a. G9a repressed PTEN expression in a methyltransferase activity-dependent manner, resulting in increased AKT and RAC1 activity. Re-expression of constitutively active RAC1 in G9a-deficient tumor cells restored oncogenic phenotypes, demonstrating its critical functions downstream of G9a. Collectively,our study provides evidence for a G9a-dependent epigenetic program that regulates tumor growth and suggests targeting G9a as a therapeutic strategy in ARMS.

Targeting autophagy using natural compounds for cancer prevention and therapy.

Deng S, Shamnmugam MK, Kumar AP, Yap CT, Sethi G, Bishayee A.

Cancer. 2019 Feb 12. doi: 10.1002/cncr.31978. [Epub ahead of print]

Abstract

Overriding FUS autoregulation in mice triggers gain-of-toxic dysfunctions in RNA metabolism and autophagy-lysosome axis

Ling SC, Dastidar SG, Tokunaga S, Ho WY, Lim K, Illieva H, Parone PA, Tyan S-H, Tse TM, Chang J-C, Platoshyn O, Bui NB, Bui A, Vetto A, Sun S, McAlonis-Downes M, Han JS, Swing D, Kapeli K, Yeo GW, Tessarollo L, Marsala M, Shaw CE, Tucker-Kellogg G, La Spada AR, Lagier-Tourenne C, Da Cruz S, Cleveland DW.

eLife. 2019 Feb 12. 8: e40811. doi: 10.7554/eLife.40811.

Abstract

Mutations in coding and non-coding regions of FUS cause amyotrophic lateral sclerosis (ALS). The latter mutations may exert toxicity by increasing FUS accumulation. We show here that broad expression within the nervous system of wild-type or either of two ALS-linked mutants of human FUS in mice produces progressive motor phenotypes accompanied by characteristic ALS-like pathology. FUS levels are autoregulated by a mechanism in which human FUS downregulates endogenous FUS at mRNA and protein levels. Increasing wild-type human FUS expression achieved by saturating this autoregulatory mechanism produces a rapidly progressive phenotype and dose-dependent lethality. Transcriptome analysis reveals mis-regulation of genes that are largely not observed upon FUS reduction. Likely mechanisms for FUS neurotoxicity include autophagy inhibition and defective RNA metabolism. Thus, our results reveal that overriding FUS autoregulation will trigger gain-of-function toxicity via altered autophagy-lysosome pathway and RNA metabolism function, highlighting a role for protein and RNA dyshomeostasis in FUS-mediated toxicity.

Understanding Factors that Motivate Research Performance and Career Longevity of STEM Postgraduates

Chen ZX, Tan M, Herberg J, Samarasekera DD, Yap C.

The Asia-Pacific Scholar Medical and Health Professional Education (TAPS). 2019; in press

Abstract

TBA