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Pushparaj PN, H’ng SC, Melendez AJ. Retraction notice to “Refining siRNA in vivo transfection: Silencing SPHK1 reveals its key role in C5a-induced inflammation in vivo” [Int. J. Biochem. Cell Biol. 40 (2008) 1817–1825]. Int J Biochem Cell Biol 2013. [DOI: 10.1016/j.biocel.2013.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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2
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Melendez AJ, Khaw AK. Retraction: Dichotomy of Ca2+ signals triggered by different phospholipid pathways in antigen stimulation of human mast cells. J Biol Chem 2013; 288:10083. [PMID: 23564903 DOI: 10.1074/jbc.a113.110944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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3
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Tay HK, Melendez AJ. Retraction: FcγRI-triggered generation of arachidonic acid and eicosanoids requires iPLA2 but not cPLA2 in human monocytic cells. J Biol Chem 2013; 288:10082. [PMID: 23564902 DOI: 10.1074/jbc.a113.308788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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4
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Zhi L, Leung BP, Melendez AJ. Retraction: Sphingosine kinase 1 regulates pro-inflammatory responses triggered by TNFα in primary human monocytes. J Cell Physiol 2012. [DOI: 10.1002/jcp.24007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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5
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Peng ZF, Chen MJ, Manikandan J, Melendez AJ, Shui G, Russo-Marie F, Whiteman M, Beart PM, Moore PK, Cheung NS. Multifaceted role of nitric oxide in an in vitro mouse neuronal injury model: transcriptomic profiling defines the temporal recruitment of death signalling cascades. J Cell Mol Med 2012; 16:41-58. [PMID: 21352476 PMCID: PMC3823092 DOI: 10.1111/j.1582-4934.2011.01288.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Nitric oxide is implicated in the pathogenesis of various neuropathologies characterized by oxidative stress. Although nitric oxide has been reported to be involved in the exacerbation of oxidative stress observed in several neuropathologies, existent data fail to provide a holistic description of how nitrergic pathobiology elicits neuronal injury. Here we provide a comprehensive description of mechanisms contributing to nitric oxide induced neuronal injury by global transcriptomic profiling. Microarray analyses were undertaken on RNA from murine primary cortical neurons treated with the nitric oxide generator DETA-NONOate (NOC-18, 0.5 mM) for 8–24 hrs. Biological pathway analysis focused upon 3672 gene probes which demonstrated at least a ±1.5-fold expression in a minimum of one out of three time-points and passed statistical analysis (one-way anova, P < 0.05). Numerous enriched processes potentially determining nitric oxide mediated neuronal injury were identified from the transcriptomic profile: cell death, developmental growth and survival, cell cycle, calcium ion homeostasis, endoplasmic reticulum stress, oxidative stress, mitochondrial homeostasis, ubiquitin-mediated proteolysis, and GSH and nitric oxide metabolism. Our detailed time-course study of nitric oxide induced neuronal injury allowed us to provide the first time a holistic description of the temporal sequence of cellular events contributing to nitrergic injury. These data form a foundation for the development of screening platforms and define targets for intervention in nitric oxide neuropathologies where nitric oxide mediated injury is causative.
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Affiliation(s)
- Zhao Feng Peng
- Key Laboratory of Biogeology and Environmental Geology of the Ministry of Education, China University of Geosciences, Wuhan, China
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6
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Newman JP, Banerjee B, Fang W, Poonepalli A, Balakrishnan L, Low GKM, Bhattacharjee RN, Akira S, Jayapal M, Melendez AJ, Baskar R, Lee HW, Hande MP. Erratum: Short dysfunctional telomeres impair the repair of arsenite-induced oxidative damage in mouse cells. J Cell Physiol 2012. [DOI: 10.1002/jcp.23064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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7
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Puneet P, McGrath MA, Tay HK, Al-Riyami L, Rzepecka J, Moochhala SM, Pervaiz S, Harnett MM, Harnett W, Melendez AJ. The helminth product ES-62 protects against septic shock via Toll-like receptor 4–dependent autophagosomal degradation of the adaptor MyD88. Nat Immunol 2011; 12:344-51. [DOI: 10.1038/ni.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 02/03/2011] [Indexed: 02/06/2023]
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8
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Chen MJ, Wong CHY, Peng ZF, Manikandan J, Melendez AJ, Tan TM, Crack PJ, Cheung NS. A global transcriptomic view of the multifaceted role of glutathione peroxidase-1 in cerebral ischemic-reperfusion injury. Free Radic Biol Med 2011; 50:736-48. [PMID: 21193029 DOI: 10.1016/j.freeradbiomed.2010.12.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/09/2010] [Accepted: 12/16/2010] [Indexed: 12/01/2022]
Abstract
Transient cerebral ischemia often results in secondary ischemic/reperfusion injury, the pathogenesis of which remains unclear. This study provides a comprehensive, temporal description of the molecular events contributing to neuronal injury after transient cerebral ischemia. Intraluminal middle cerebral artery occlusion (MCAO) was performed to induce a 2-h ischemia with reperfusion. Microarray analysis was then performed on the infarct cortex of wild-type (WT) and glutathione peroxidase-1 (a major antioxidant enzyme) knockout (Gpx1(-/-)) mice at 8 and 24h postreperfusion to identify differential gene expression profile patterns and potential alternative injury cascades in the absence of Gpx1, a crucial antioxidant enzyme, in cerebral ischemia. Genes with at least ±1.5-fold change in expression at either time point were considered significant. Global transcriptomic analyses demonstrated that 70% of the WT-MCAO profile overlapped with that of Gpx1(-/-)-MCAO, and 28% vice versa. Critical analysis of the 1034 gene probes specific to the Gpx1(-/-)-MCAO profile revealed regulation of additional novel pathways, including the p53-mediated proapoptotic pathway and Fas ligand (CD95/Apo1)-mediated pathways; downplay of the Nrf2 antioxidative cascade; and ubiquitin-proteasome system dysfunction. Therefore, this comparative study forms the foundation for the establishment of screening platforms for target definition in acute cerebral ischemia intervention.
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MESH Headings
- Animals
- Apoptosis/genetics
- Disease Models, Animal
- Fas Ligand Protein/genetics
- Gene Expression Profiling
- Genes, p53
- Glutathione Peroxidase/genetics
- Glutathione Peroxidase/metabolism
- Infarction, Middle Cerebral Artery/genetics
- Infarction, Middle Cerebral Artery/metabolism
- Infarction, Middle Cerebral Artery/pathology
- Inflammation
- Ischemic Attack, Transient/genetics
- Ischemic Attack, Transient/metabolism
- Ischemic Attack, Transient/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- NF-E2-Related Factor 2/genetics
- Oligonucleotide Array Sequence Analysis
- Oxidation-Reduction
- Polymerase Chain Reaction
- Reactive Oxygen Species
- Reperfusion Injury/genetics
- Reperfusion Injury/metabolism
- Reperfusion Injury/pathology
- Reperfusion Injury/surgery
- Signal Transduction
- Ubiquitin-Protein Ligase Complexes/genetics
- Glutathione Peroxidase GPX1
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9
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Chen MJ, Peng ZF, Manikandan J, Melendez AJ, Tan GS, Chung CM, Li QT, Tan TM, Deng LW, Whiteman M, Beart PM, Moore PK, Cheung NS. Gene profiling reveals hydrogen sulphide recruits death signaling via the N-methyl-D-aspartate receptor identifying commonalities with excitotoxicity. J Cell Physiol 2011; 226:1308-22. [DOI: 10.1002/jcp.22459] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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10
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Choy MS, Chen MJ, Manikandan J, Peng ZF, Jenner AM, Melendez AJ, Cheung NS. Up-regulation of endoplasmic reticulum stress-related genes during the early phase of treatment of cultured cortical neurons by the proteasomal inhibitor lactacystin. J Cell Physiol 2011; 226:494-510. [PMID: 20683911 DOI: 10.1002/jcp.22359] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inhibition of proteasome degradation pathway has been implicated in neuronal cell death leading to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. We and others demonstrated that treatment of cortical neurons with the proteasomal inhibitor lactacystin leads to apoptosis. We discovered by microarray analysis that lactacystin treatment modulates the expression of both potentially neuroprotective as well as pro-apoptotic genes in neurons. However, the significance of the genes which upon transcriptional modulation contributed to proteasomal inhibition-induced apoptosis, remained unidentified. By employing microarray analysis to decipher the time-dependent changes in transcription of these genes in cultured cortical neurons, we discovered different groups of genes were transcriptionally regulated in the early and late phase of lactacystin-induced cell death. In the early phase, several neuroprotective genes such as those encoding the proteasome subunits and ubiquitin-associated enzymes, as well as the heat-shock proteins (HSP) were up-regulated. However, the pro-apoptotic endoplasmic reticulum (ER) stress-associated genes were also up-regulated at the early phase of lactacystin-induced neuronal cell death. In the late phase, genes encoding antioxidants and calcium-binding proteins were up-regulated while those associated with cholesterol biosynthesis were down-regulated. The data suggest that ER stress may participate in mediating the apoptotic responses induced by proteasomal inhibition. The up-regulation of the neuroprotective antioxidant genes and calcium-binding protein genes and down-regulation of the cholesterol biosynthesis genes in the later phase are likely consequences of stimulation of the pro-apoptotic signaling pathways in the early phase of lactacystin treatment.
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Affiliation(s)
- Meng Shyan Choy
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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11
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Lai WQ, Melendez AJ, Leung BP. Role of sphingosine kinase and sphingosine-1-phosphate in inflammatory arthritis. World J Biol Chem 2010; 1:321-6. [PMID: 21537466 PMCID: PMC3083938 DOI: 10.4331/wjbc.v1.i11.321] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 02/05/2023] Open
Abstract
The importance of sphingosine kinase (SphK) and sphingosine-1-phosphate (S1P) in inflammation has been extensively demonstrated. As an intracellular second messenger, S1P plays an important role in calcium signaling and mobilization, and cell proliferation and survival. Activation of various plasma membrane receptors, such as the formyl methionyl leucyl phenylalanine receptor, C5a receptor, and tumor necrosis factor α receptor, leads to a rapid increase in intracellular S1P level via SphK stimulation. SphK and S1P are implicated in various chronic autoimmune conditions such as rheumatoid arthritis, primary Sjögren’s syndrome, and inflammatory bowel disease. Recent studies have demonstrated the important role of SphK and S1P in the development of arthritis by regulating the pro-inflammatory responses. These novel pathways represent exciting potential therapeutic targets.
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Affiliation(s)
- Wen-Qi Lai
- Wen-Qi Lai, Alirio J Melendez, Bernard P Leung, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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12
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Yap YW, Chen MJ, Choy MS, Peng ZF, Whiteman M, Manikandan J, Melendez AJ, Cheung NS. Temporal transcriptomic profiling reveals cellular targets that govern survival in HOCl-mediated neuronal apoptosis. Life Sci 2010; 87:457-67. [DOI: 10.1016/j.lfs.2010.08.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/02/2010] [Accepted: 08/19/2010] [Indexed: 12/19/2022]
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13
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Sethu S, Pushparaj PN, Melendez AJ. Phospholipase D1 mediates TNFalpha-induced inflammation in a murine model of TNFalpha-induced peritonitis. PLoS One 2010; 5:e10506. [PMID: 20463923 PMCID: PMC2864766 DOI: 10.1371/journal.pone.0010506] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 04/12/2010] [Indexed: 01/01/2023] Open
Abstract
Background Tumor Necrosis Factor alpha (TNFα) is a pleiotropic cytokine extensively studied for its role in the pathogenesis of a variety of disease conditions, including in inflammatory diseases. We have recently shown that, in vitro, that TNFα utilizes PLD1 to mediate the activation of NFκB and ERK1/2 in human monocytes. The aim of this study was to investigate the role(s) played by phospholipase D1 (PLD1) in TNFα-mediated inflammatory responses in vivo. Methodology/Findings Studies were performed in vivo using a mouse model of TNFα-induced peritonitis. The role of PLD1 was investigated by functional genomics, utilizing a specific siRNA to silence the expression of PLD1. Administration of the siRNA against PLD1 significantly reduced PLD1 levels in vivo. TNFα triggers a rapid pyrogenic response, but the in vivo silencing of PLD1 protects mice from the TNFα-induced rise in temperature. Similarly TNFα caused an increase in the serum levels of IL-6, MIP-1α and MIP-1β: this increase in cytokine/chemokine levels was inhibited in mice where PLD1 had been silenced. We then induced acute peritonitis with TNFα. Intraperitoneal injection of TNFα triggered a rapid increase in vascular permeability, and the influx of neutrophils and monocytes into the peritoneal cavity. By contrast, in mice where PLD1 had been silenced, the TNFα-triggered increase in vascular permeability and phagocyte influx was substantially reduced. Furthermore, we also show that the TNFα-mediated upregulation of the cell adhesion molecules VCAM and ICAM1, in the vascular endothelium, were dependent on PLD1. Conclusions These novel data demonstrate a critical role for PLD1 in TNFα-induced inflammation in vivo and warrant further investigation. Indeed, our results suggest PLD1 as a novel target for treating inflammatory diseases, where TNFα play key roles: these include diseases ranging from sepsis to respiratory and autoimmune diseases; all diseases with considerable unmet medical need.
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Affiliation(s)
- Swaminathan Sethu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Peter N. Pushparaj
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Alirio J. Melendez
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, Scotland, United Kingdom
- * E-mail:
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14
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Hueber AJ, Asquith DL, Miller AM, Reilly J, Kerr S, Leipe J, Melendez AJ, McInnes IB. Cutting Edge: Mast Cells Express IL-17A in Rheumatoid Arthritis Synovium. J I 2010; 184:3336-40. [DOI: 10.4049/jimmunol.0903566] [Citation(s) in RCA: 292] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Hegde A, Tamizhselvi R, Manikandan J, Melendez AJ, Moochhala SM, Bhatia M. Substance P in polymicrobial sepsis: molecular fingerprint of lung injury in preprotachykinin-A-/- mice. Mol Med 2010; 16:188-98. [PMID: 20454520 DOI: 10.2119/molmed.2009.00166] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 02/07/2010] [Indexed: 12/22/2022] Open
Abstract
Deletion of mouse preprotachykinin-A (PPTA), which encodes mainly for neuropeptide substance P, has been shown to protect against lung injury and mortality in sepsis. This study explored microarray-based differential gene expression profiles in mouse lung tissue 8 h after inducing microbial sepsis and the effect of PPTA gene deletion. A range of genes differentially expressed (more than two-fold) in microarray analysis was assessed, comparing wild-type and PPTA-knockout septic mice with their respective sham controls, and the data were further validated. Genetic deletion of substance P resulted in a significantly different expression profile of genes involved in inflammation and immunomodulation after the induction of sepsis, compared with wild-type mice. Interestingly, apart from the various proinflammatory mediators, the antiinflammatory cytokine interleukin-1 receptor antagonist gene (IL1RN) was also elevated much more in PPTA(-/-) septic mice. In addition, semiquantitative RT-PCR analysis supported the microarray data. The microarray data imply that the elevated levels of inflammatory gene expression in the early stages of sepsis in PPTA-knockout mice are possibly aimed to resolve the infection without excessive immunosuppression. As scientists are divided over the effects of pro- and antiinflammatory mediators in sepsis, it seems prudent to define the status depending on a complete genome profile. This is the first report exploring pulmonary gene expression profiles using microarray analysis in PPTA-knockout mice subjected to cecal ligation and puncture-induced sepsis and providing additional biological insight into the protection received against lung injury and mortality.
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Affiliation(s)
- Akhil Hegde
- Cardiovascular Biology Program, Department of Pharmacology, Yong Loo Lin School of Medicine,National University of Singapore, Singapore
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16
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Xu D, Jiang HR, Li Y, Pushparaj PN, Kurowska-Stolarska M, Leung BP, Mu R, Tay HK, McKenzie ANJ, McInnes IB, Melendez AJ, Liew FY. IL-33 exacerbates autoantibody-induced arthritis. J Immunol 2010; 184:2620-6. [PMID: 20139274 DOI: 10.4049/jimmunol.0902685] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Rheumatoid arthritis pathogenesis comprises dysregulation in both innate and adaptive immunity. There is therefore intense interest in the factors that integrate these immunologic pathways in rheumatoid arthritis. In this paper, we report that IL-33, a novel member of the IL-1 family, can exacerbate anti-glucose-6-phosphate isomerase autoantibody-induced arthritis (AIA). Mice lacking ST2 (ST2(-/-)), the IL-33 receptor alpha-chain, developed attenuated AIA and reduced expression of articular proinflammatory cytokines. Conversely, treatment of wild-type mice with rIL-33 significantly exacerbated AIA and markedly enhanced proinflammatory cytokine production. However, IL-33 failed to increase the severity of the disease in mast cell-deficient or ST2(-/-) mice. Furthermore, mast cells from wild-type, but not ST2(-/-), mice restored the ability of ST2(-/-) recipients to mount an IL-33-mediated exacerbation of AIA. IL-33 also enhanced autoantibody-mediated mast cell degranulation in vitro and in synovial tissue in vivo. Together these results demonstrate that IL-33 can enhance autoantibody-mediated articular inflammation via promoting mast cell degranulation and proinflammatory cytokine production. Because IL-33 is derived predominantly from synovial fibroblasts, this finding provides a novel mechanism whereby a host tissue-derived cytokine can regulate effector adaptive immune response via enhancing innate cellular activation in inflammatory arthritis.
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Affiliation(s)
- Damo Xu
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK.
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17
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Harnett MM, Melendez AJ, Harnett W. The therapeutic potential of the filarial nematode-derived immunodulator, ES-62 in inflammatory disease. Clin Exp Immunol 2009; 159:256-67. [PMID: 19968663 DOI: 10.1111/j.1365-2249.2009.04064.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The dramatic recent rise in the incidence of allergic or autoimmune inflammatory diseases in the West has been proposed to reflect the lack of appropriate priming of the immune response by infectious agents such as parasitic worms during childhood. Consistent with this, there is increasing evidence supporting an inverse relationship between worm infection and T helper type 1/17 (Th1/17)-based inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease, type 1 diabetes and multiple sclerosis. Perhaps more surprisingly, given that such worms often induce strong Th2-type immune responses, there also appears to be an inverse correlation between parasite load and atopy. These findings therefore suggest that the co-evolution of helminths with hosts, which has resulted in the ability of worms to modulate inflammatory responses to promote parasite survival, has also produced the benefit of protecting the host from pathological lesions arising from aggressive proinflammatory responses to infection or, indeed, aberrant inflammatory responses underlying autoimmune and allergic disorders. By focusing upon the properties of the filarial nematode-derived immunomodulatory molecule, ES-62, in this review we shall discuss the potential of exploiting the immunomodulatory products of parasitic worms to identify and develop novel therapeutics for inflammation.
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Affiliation(s)
- M M Harnett
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Centre, University of Glasgow, Glasgow, UK.
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18
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Jayapal M, Bhattacharjee RN, Melendez AJ, Hande MP. Environmental toxicogenomics: a post-genomic approach to analysing biological responses to environmental toxins. Int J Biochem Cell Biol 2009; 42:230-40. [PMID: 19836462 DOI: 10.1016/j.biocel.2009.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 09/09/2009] [Accepted: 10/09/2009] [Indexed: 11/30/2022]
Abstract
Environmental genomics has revolutionised how researchers can study the molecular basis of adverse effects of environmental toxicants. It is expected that the new discipline will afford efficient and high-throughput means to delineate mechanisms of action, risk assessment, identify and understand basic pathogenic mechanisms that are critical to disease progression, predict toxicity of unknown agents and to more precisely phenotype disease subtypes. Previously, we have demonstrated the potential of environmental genomics in a toxicant exposure model and, perhaps, this might become a crucial tool in biological response marker or biomarker discovery. To illustrate how toxicogenomics can be useful, we provide here an overview of some of the past and potential future aspects of environmental genomics. The present article also reviews the principles and technological concerns, and the standards and databases of toxicogenomics. In addition, applications of toxicogenomics in drug target identifications and validation strategies are also discussed.
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Affiliation(s)
- Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597, Singapore
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19
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Abstract
Sphingolipid-metabolizing enzymes control the critical balance of the cellular levels of sphingolipids, including the apoptotic inducing ceramide (Cer) and the proliferative inducing sphingosine 1-phosphate (S1P). The production of S1P, catalyzed by the action of sphingosine kinases (SPHKs), is known to be critical for many cellular processes. However, it is suggested that SPHK, and/or its catalytic product S1P, plays critical roles in various diseases including autoimmune diseases, cancer, and allergies. However, there is a great limitation of specific pharmacological inhibitors for SPHKs. In this paper, we describe a novel and stereoselective method of synthesizing SPHKs inhibitors. We generated a number of novel compounds and identified a number of specific inhibitors of human SPHKs. These compounds demonstrated inhibition of SPHKs at micromolar concentrations, making them more potent than dimethylsphingosine (DMS), a well-known inhibitor of SPHKs. In particular, one of the inhibitors was found to be selective toward a particular isoform of SPHK.
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Affiliation(s)
- Lingkai Wong
- Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543, Singapore
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20
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Lai WQ, Irwan AW, Goh HH, Melendez AJ, McInnes IB, Leung BP. Distinct roles of sphingosine kinase 1 and 2 in murine collagen-induced arthritis. J Immunol 2009; 183:2097-103. [PMID: 19596980 DOI: 10.4049/jimmunol.0804376] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Sphingosine kinase (SphK) phosphorylates sphingosine into sphingosine-1-phosphate (S1P). S1P plays a critical role in angiogenesis, inflammation, and various pathologic conditions. To date, two mammalian isoenzymes, SphK1 and SphK2, have been identified. Although both SphK1 and SphK2 share overall homology and produce the common product, S1P, it has been proposed they display different unique and separate functions. In this study, we examined the role of SphK1 and SphK2 in a murine collagen-induced arthritis model by down-regulating each isoenzyme via specific small interfering RNA (siRNA). Prophylactic i.p. administration of SphK1 siRNA significantly reduced the incidence, disease severity, and articular inflammation compared with control siRNA recipients. Treatment of SphK1 siRNA also down-regulated serum levels of S1P, IL-6, TNF-alpha, IFN-gamma, and IgG2a anti-collagen Ab. Ex vivo analysis demonstrated significant suppression of collagen-specific proinflammatory/Th1 cytokine (IL-6, TNF-alpha, IFN-gamma) release in SphK siRNA-treated mice. Interestingly, mice received with SphK2 siRNA develop more aggressive disease; higher serum levels of IL-6, TNF-alpha, and IFN-gamma; and proinflammatory cytokine production to collagen in vitro when compared with control siRNA recipients. Together, these results demonstrate the distinct immunomodulatory roles of SphK1 and SphK2 in the development of inflammatory arthritis by regulating the release of proinflammatory cytokines and T cell responses. These findings raise the possibility that drugs which specifically target SphK1 activity may play a beneficial role in the treatment of inflammatory arthritis.
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Affiliation(s)
- Wen-Qi Lai
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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21
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Pushparaj PN, Tay HK, Wang CC, Hong W, Melendez AJ. VAMP8 is essential in anaphylatoxin-induced degranulation, TNF-alpha secretion, peritonitis, and systemic inflammation. J Immunol 2009; 183:1413-8. [PMID: 19564343 DOI: 10.4049/jimmunol.0804061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
VAMP8, a member of the soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) family of fusion proteins, initially characterized in endosomal and endosomal-lysosomal fusion, may also function in regulated exocytosis. VAMP8 physiological function in inflammation has not been elucidated. In this paper, we show that deficiency of VAMP8 protects mice from anaphylatoxin (C5a)-induced neutropenia, peritonitis, and systemic inflammation. We show that, in vivo, VAMP8 deletion inhibits neutropenia and phagocyte recruitment. We also show that in macrophages, VAMP8 localizes on secretory granules and degranulation is inhibited in VAMP8-deficient macrophages. Moreover, VAMP8(-/-) mice show reduced systemic inflammation with inhibition of serum TNF-alpha levels, whereas IL-1beta, IL-6, and MIP1alpha release are not affected. In wild-type macrophages, TNF-alpha colocalizes with VAMP8-positive vesicles, and in VAMP8-deficient macrophages, the TNF-alpha release is inhibited. Furthermore, VAMP8 regulates the release of TNF-alpha and beta-hexosaminidase triggered by fMLP, and VAMP8(-/-) mice are protected from fMLP-induced peritonitis. These data demonstrate that the VAMP8 vesicle-associated-SNARE is required for the proper trafficking of secretory lysosomal granules for exocytosis in macrophages and for the release of the potent proinflammatory cytokine, TNF-alpha.
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Affiliation(s)
- Peter N Pushparaj
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
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22
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Pushparaj PN, Manikandan J, Tay HK, H'ng SC, Kumar SD, Pfeilschifter J, Huwiler A, Melendez AJ. Sphingosine Kinase1 Is Pivotal for FcεRI-Mediated Mast Cell Signaling and Functional Responses In Vitro and In Vivo. J Immunol 2009; 183:221-7. [DOI: 10.4049/jimmunol.0803430] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Pushparaj PN, Tay HK, H'ng SC, Pitman N, Xu D, McKenzie A, Liew FY, Melendez AJ. The cytokine interleukin-33 mediates anaphylactic shock. Proc Natl Acad Sci U S A 2009; 106:9773-8. [PMID: 19506243 PMCID: PMC2700978 DOI: 10.1073/pnas.0901206106] [Citation(s) in RCA: 238] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Indexed: 01/12/2023] Open
Abstract
Anaphylactic shock is characterized by elevated immunoglobulin-E (IgE) antibodies that signal via the high affinity Fc epsilon receptor (Fc epsilonRI) to release inflammatory mediators. Here we report that the novel cytokine interleukin-33 (IL-33) potently induces anaphylactic shock in mice and is associated with the symptom in humans. IL-33 is a new member of the IL-1 family and the ligand for the orphan receptor ST2. In humans, the levels of IL-33 are substantially elevated in the blood of atopic patients during anaphylactic shock, and in inflamed skin tissue of atopic dermatitis patients. In murine experimental atopic models, IL-33 induced antigen-independent passive cutaneous and systemic anaphylaxis, in a T cell-independent, mast cell-dependent manner. In vitro, IL-33 directly induced degranulation, strong eicosanoid and cytokine production in IgE-sensitized mast cells. The molecular mechanisms triggering these responses include the activation of phospholipase D1 and sphingosine kinase1 to mediate calcium mobilization, Nuclear factor-kappaB activation, cytokine and eicosanoid secretion, and degranulation. This report therefore reveals a hitherto unrecognized pathophysiological role of IL-33 and suggests that IL-33 may be a potential therapeutic target for anaphylaxis, a disease of considerable unmet medical need.
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Affiliation(s)
- Peter N. Pushparaj
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
| | - Hwee Kee Tay
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
| | - Shiau Chen H'ng
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and
| | - Nick Pitman
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
| | - Damo Xu
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
| | - Andrew McKenzie
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Foo Y. Liew
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
| | - Alirio J. Melendez
- Division of Immunology, Infection and Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, Scotland, United Kingdom
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and
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24
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Issuree PDA, Pushparaj PN, Pervaiz S, Melendez AJ. Resveratrol attenuates C5a‐induced inflammatory responses
in vitro
and
in vivo
by inhibiting phospholipase D and sphingosine kinase activities. FASEB J 2009; 23:2412-24. [DOI: 10.1096/fj.09-130542] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
| | - Peter N. Pushparaj
- Department of PhysiologyYong Loo Lin School of MedicineSingapore
- Medicine‐Immunology, Infection, and InflammationGlasgow Biomedical Research CentreUniversity of GlasgowGlasgowUK
| | - Shazib Pervaiz
- Department of PhysiologyYong Loo Lin School of MedicineSingapore
- NUS Graduate School for Integrative Sciences and EngineeringSingapore
- Duke‐NUS Graduate Medical SchoolNational University of SingaporeSingapore
- Singapore‐Massachusetts Institute of Technology AllianceSingapore
| | - Alirio J. Melendez
- Department of PhysiologyYong Loo Lin School of MedicineSingapore
- NUS Graduate School for Integrative Sciences and EngineeringSingapore
- Medicine‐Immunology, Infection, and InflammationGlasgow Biomedical Research CentreUniversity of GlasgowGlasgowUK
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25
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Abstract
Mast cell activation is a central event in allergic diseases, and investigating the signalling pathways triggered during mast cell activation may lead to the discovery of novel therapeutic targets. Mast cells can be activated by a multitude of stimuli including antibodies/antigen, cytokines/chemokines and neuropeptides, resulting in a variety of responses including the immediate release of potent inflammatory mediators. Moreover, recent data suggest that mast cell-mediated responses are also influenced by the differential sphingolipids/sphingosine to sphingosine-1-phosphate ratio. The importance of sphingolipids as potent biological mediators of both intracellular and extracellular responses is being increasingly recognized and accepted; it is now appreciated that activation of mast cells, via the high-affinity IgE-receptor (FcepsilonRI) leads to the activation of sphingosine kinases (SphK), resulting in increased formation of sphingosine-1-phosphate. Furthermore, FcepsilonRI activates SphK-dependent calcium mobilization in mast cells, leading to degranulation, cytokine, and eicosanoid production, and chemotaxis. In the past two years a critical role for SphK in allergic responses in vivo has emerged. In this review, I focus on the current understanding of the role of sphingosine kinases during mast cell signalling in vitro and their role during hypersensitivity responses in vivo, and discuss the potential of these enzymes as novel therapeutic targets to treat allergic diseases.
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Affiliation(s)
- Alirio J Melendez
- Division of Immunology, Infection and Inflammation, Faculty of Medicine, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, Scotland, UK.
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26
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Lai WQ, Irwan AW, Goh HH, Howe HS, Yu DT, Valle-Oñate R, McInnes IB, Melendez AJ, Leung BP. Anti-Inflammatory Effects of Sphingosine Kinase Modulation in Inflammatory Arthritis. J Immunol 2008; 181:8010-7. [DOI: 10.4049/jimmunol.181.11.8010] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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27
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Mansoor M, Melendez AJ. Advances in antisense oligonucleotide development for target identification, validation, and as novel therapeutics. Gene Regul Syst Bio 2008; 2:275-95. [PMID: 19787090 PMCID: PMC2733095 DOI: 10.4137/grsb.s418] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Antisense oligonucleotides (As-ODNs) are single stranded, synthetically prepared strands of deoxynucleotide sequences, usually 18–21 nucleotides in length, complementary to the mRNA sequence of the target gene. As-ODNs are able to selectively bind cognate mRNA sequences by sequence-specific hybridization. This results in cleavage or disablement of the mRNA and, thus, inhibits the expression of the target gene. The specificity of the As approach is based on the probability that, in the human genome, any sequence longer than a minimal number of nucleotides (nt), 13 for RNA and 17 for DNA, normally occurs only once. The potential applications of As-ODNs are numerous because mRNA is ubiquitous and is more accessible to manipulation than DNA. With the publication of the human genome sequence, it has become theoretically possible to inhibit mRNA of almost any gene by As-ODNs, in order to get a better understanding of gene function, investigate its role in disease pathology and to study novel therapeutic targets for the diseases caused by dysregulated gene expression. The conceptual simplicity, the availability of gene sequence information from the human genome, the inexpensive availability of synthetic oligonucleotides and the possibility of rational drug design makes As-ODNs powerful tools for target identification, validation and therapeutic intervention. In this review we discuss the latest developments in antisense oligonucleotide design, delivery, pharmacokinetics and potential side effects, as well as its uses in target identification and validation, and finally focus on the current developments of antisense oligonucleotides in therapeutic intervention in various diseases.
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Affiliation(s)
- Moizza Mansoor
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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28
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Mansoor M, Melendez AJ. Recent trials for FTY720 (fingolimod): a new generation of immunomodulators structurally similar to sphingosine. Rev Recent Clin Trials 2008; 3:62-9. [PMID: 18474015 DOI: 10.2174/157488708783330486] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most of the conventional immunosuppressive drugs act by inhibiting the activation of enzymes, production of cytokines or proliferation of immune cells. Recently much attention is given to a new class of inhibitors that act by counteracting the functions of the lysophospholid sphingosine-1-phosphate (S1P). S1P is emerging as a potent stimulator of several immune cells and is critical for lymphocyte migration. The sphingosine analogue, FTY720 (fingolimod), a high affinity agonist of sphingosine-1-phosphate type-1 receptor (S1P-1), acts primarily by sequestering lymphocytes within peripheral lymphoid organs rendering them incapable of migrating to the sites of inflammation. Phase I, II and III, clinical trials comparing the efficacy of FTY720 containing regimens to conventional immunosuppressive regimens in de novo renal transplant patients, have been conducted. Moreover, clinical trials are also on-going in patients with relapsing-remitting multiple sclerosis showing obvious benefit for patients receiving FTY720. In this review, we focus on the transition of this novel compound from bench to clinical trials, and discuss the clinical potential of this drug in autoimmune diseases and in transplantation immunology.
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Affiliation(s)
- Moizza Mansoor
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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29
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Lai WQ, Goh HH, Bao Z, Wong WSF, Melendez AJ, Leung BP. The role of sphingosine kinase in a murine model of allergic asthma. J Immunol 2008; 180:4323-9. [PMID: 18322246 DOI: 10.4049/jimmunol.180.6.4323] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Asthma is an allergic disease characterized by chronic airway eosinophilia and pulmonary infiltration of lymphocytes, particularly of the Th2 subtype, macrophages and mast cells. Previous studies have shown a pivotal role for sphingosine kinase (SphK) on various proinflammatory cells, such as lymphocyte and eosinophil migration and mast cell degranulation. We therefore examined the roles of SphK in a murine model of allergic asthma. In mice previously sensitized to OVA, i.p. administration of N,N-dimethylsphingosine (DMS), a potent SphK inhibitor, significantly reduced the total inflammatory cell infiltrate and eosinophilia and the IL-4, IL-5, and eotaxin levels in bronchoalveolar lavage fluid in response to inhaled OVA challenge. In addition, DMS significantly suppressed OVA-induced inflammatory infiltrates and mucus production in the lungs, and airway hyperresponsiveness to methacholine in a dose-dependent manner. OVA-induced lymphocyte proliferation and IL-4 and IL-5 secretion were reduced in thoracic lymph node cultures from DMS-treated mice. Moreover, similar reduction in inflammatory infiltrates, bronchoalveolar lavage, IL-4, IL-5, eotaxin, and serum OVA-specific IgE levels was observed in mice with SphK1 knock-down via small interfering RNA approach. Together, these data demonstrate the therapeutic potential of SphK modulation in allergic airways disease.
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Affiliation(s)
- Wen-Qi Lai
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
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30
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Abstract
The primary characteristic features of any inflammatory or infectious lesions are immune cell infiltration, cellular proliferation, and the generation of proinflammatory mediators. TNF-alpha is a potent proinflammatory and immuno-regulatory cytokine. Decades of research have been focused on the physiological/pathophysiological events triggered by TNF-alpha. However, the signaling network initiated by TNF-alpha in human leukocytes is still poorly understood. In this study, we report that TNF-alpha activates phospholipase D1 (PLD1), in a dose-dependent manner, and PLD1 is required for the activation of sphingosine kinase and cytosolic calcium signals. PLD1 is also required for NFkappaB and ERK1/2 activation in human monocytic cells. Using antisense oligonucleotides to reduce specifically the expression of PLD isozymes showed PLD1, but not PLD2, to be coupled to TNF-alpha signaling and that PLD1 is required to mediate receptor activation of sphingosine kinase and calcium transients. In addition, the coupling of TNF-alpha to activation of the phosphorylation of ERK1/2 and the activation of NFkappaB were inhibited by pretreating cells with antisense to PLD1, but not to PLD2; thus, demonstrating a specific requirement for PLD1. Furthermore, use of antisense oligonucleotides to reduce expression of PLD1 or PLD2 demonstrated that PLD1 is required for TNF-alpha-induced production of several important cytokines, such as IL-1beta, IL-5, IL-6, and IL-13, in human monocytes. These studies demonstrate the critical role of PLD1 in the intracellular signaling cascades initiated by TNF-alpha and its functional role for coordinating the signals to inflammatory responses.
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Affiliation(s)
- Swaminathan Sethu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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31
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Jessica Chen M, Sepramaniam S, Armugam A, Shyan Choy M, Manikandan J, Melendez AJ, Jeyaseelan K, Sang Cheung N. Water and ion channels: crucial in the initiation and progression of apoptosis in central nervous system? Curr Neuropharmacol 2008; 6:102-16. [PMID: 19305791 PMCID: PMC2647147 DOI: 10.2174/157015908784533879] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 09/09/2007] [Accepted: 10/01/2007] [Indexed: 12/14/2022] Open
Abstract
Programmed cell death (PCD), is a highly regulated and sophisticated cellular mechanism that commits cell to isolated death fate. PCD has been implicated in the pathogenesis of numerous neurodegenerative disorders. Countless molecular events underlie this phenomenon, with each playing a crucial role in death commitment. A precedent event, apoptotic volume decrease (AVD), is ubiquitously observed in various forms of PCD induced by different cellular insults. Under physiological conditions, cells when subjected to osmotic fluctuations will undergo regulatory volume increase/decrease (RVI/RVD) to achieve homeostatic balance with neurons in the brain being additionally protected by the blood-brain-barrier. However, during AVD following apoptotic trigger, cell undergoes anistonic shrinkage that involves the loss of water and ions, particularly monovalent ions e.g. K(+), Na(+) and Cl(-). It is worthwhile to concentrate on the molecular implications underlying the loss of these cellular components which posed to be significant and crucial in the successful propagation of the apoptotic signals. Microarray and real-time PCR analyses demonstrated several ion and water channel genes are regulated upon the onset of lactacystin (a proteosomal inhibitor)-mediated apoptosis. A time course study revealed that gene expressions of water and ion channels are being modulated just prior to apoptosis, some of which are aquaporin 4 and 9, potassium channels and chloride channels. In this review, we shall looked into the molecular protein machineries involved in the execution of AVD in the central nervous system (CNS), and focus on the significance of movements of each cellular component in affecting PCD commitment, thus provide some pharmacological advantages in the global apoptotic cell death.
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Affiliation(s)
- Minghui Jessica Chen
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Sugunavathi Sepramaniam
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Arunmozhiarasi Armugam
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Meng Shyan Choy
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Jayapal Manikandan
- Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Alirio J Melendez
- Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Kandiah Jeyaseelan
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Nam Sang Cheung
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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32
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Pushparaj PN, H'ng SC, Melendez AJ. Refining siRNA in vivo transfection: silencing SPHK1 reveals its key role in C5a-induced inflammation in vivo. Int J Biochem Cell Biol 2008; 40:1817-25. [PMID: 18308614 DOI: 10.1016/j.biocel.2008.01.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2007] [Revised: 01/16/2008] [Accepted: 01/16/2008] [Indexed: 11/30/2022]
Abstract
The transfection of siRNA in vivo is essential for the study of gene functions, target validation, and for gene therapy. However, the successful delivery of siRNA in whole organisms is still very difficult to achieve. A high-pressure delivery technique, called the "hydrodynamics" method, has been used for siRNA transfection in mice. However, it is a method based on a high-speed and high-volume of i.v. injection, which makes it very difficult to implement in vivo, due to vascular breakage. Here, we systematically investigated ways to optimize the siRNA delivery, in order to avoid strong side effects, while achieving a high-efficiency siRNA-gene knockdown. We show here that the amount of siRNA delivered is crucial, as using too little or too much siRNA minimizes the knockdown effect. We demonstrate that by carefully identifying an optimal-minimal volume, and an optimal amount of siRNA, we achieve a high knockdown effect, with a 100% survival rate. We have previously shown that SphK1 plays a key role in anaphylatoxin (C5a) signaling in neutrophils and macrophages. Our approach, optimizing the dosage of siRNA, allowed us to successfully silence our target gene-product (SphK1) in vivo, and enabled us to validate SphK1 as a key player in our in vivo model of C5a-induced acute peritonitis and systemic inflammation including multi-organ damage, demonstrating that this improved siRNA-silencing method not only allowed us to identify SphK1 as a key therapeutic target, but brings us a step closer to the usage of siRNA for therapeutic intervention.
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Affiliation(s)
- Peter N Pushparaj
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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33
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Peng ZF, Chen MJ, Yap YW, Manikandan J, Melendez AJ, Choy MS, Moore PK, Cheung NS. Proteasome inhibition: an early or late event in nitric oxide-induced neuronal death? Nitric Oxide 2007; 18:136-45. [PMID: 18078831 DOI: 10.1016/j.niox.2007.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 11/12/2007] [Accepted: 11/15/2007] [Indexed: 11/16/2022]
Abstract
Nitric oxide (NO), ubiquitously expressed in the central nervous system, has been perceived to be a potential neuromodulator. Employing cultured murine primary cortical neurons, NO resulted in an inhibition of the ubiquitin-proteasome system (UPS) with a dose- and time-dependent decrease in cell viability. This is consistent with a previous study that reported a dysfunction of UPS with consequential apoptotic death in macrophage cell with NO treatment. However, it cannot be unclear if the drop in UPS efficiency is directly imposed on by NO. Therefore by using microarray analysis, our study revealed an early down-regulation or non-significant differential expression of genes encoding UPS proteins in NOC-18 (NO donor)-treated neurons as compared to an observed elevation of corresponding gene expression genes in lactacystin (classical proteasome inhibitor)-treated neurons (conducted earlier). Furthermore, time-course analysis of proteasome activity in NOC-18-treated neurons demonstrated a late onset of reduction. This is intriguing as it is well established that in an exclusive proteasome dysfunction-induced cell death, a compensatory feedback mechanism will be activated with an initial and concerted up-regulation of genes encoding proteins involved in UPS as seen when neurons were treated with lactacystin. Thus, it is highly suggestive that NO-triggered neuronal death takes on a different signaling cascade from that of a classical proteasome inhibitor, and that the late reduction of proteasome activity is a downstream event following the activation of apoptotic cellular signaling cascade. In intracellular condition, the proteasome is not NO preferred primary target responsible for the trigger of the cell death machinery. In conclusion, we presented novel findings that shed light into NO-induced cell death signaling cascade, which would be important in understanding the pathogenesis of neurodegenerative disorders such as Parkinson's disease.
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Affiliation(s)
- Zhao Feng Peng
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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34
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Chi Z, Melendez AJ. Role of cell adhesion molecules and immune-cell migration in the initiation, onset and development of atherosclerosis. Cell Adh Migr 2007; 1:171-5. [PMID: 19262139 DOI: 10.4161/cam.1.4.5321] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Atherosclerosis is currently the leading factor of death in developed countries. It is now recognized as a chronic immune-inflammatory disease, whose initial stages involve the interaction of leukocytes with the endothelial monolayer. The initial stage of atherosclerosis requires the interplay of various cell adhesion molecules and immune cells to trigger leukocyte and lymphocyte migration from the circulating blood into the arterial intima. Studies have unveiled the role of inflammatory mediators in the initiation, onset and progression of the disease. During the last few years we have gained a greater understanding of the mechanism that modulates monocyte, macrophage and T cell infiltration, the role these cells play in the atherosclerotic lesion, in the formation of the fibrous plaque formation with the consequent narrowing of the arteries, and the mechanisms that lead to plaque rupture and the formation of thrombi and emboli. This review talks about the leukocyte recruitment in early atherosclerosis, the formation of the plaque, and the mechanisms that lead to thrombosis in advanced atherosclerosis. Finally, we discuss the potential for novel therapies to treat this disease.
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Affiliation(s)
- Zhang Chi
- Graduate Program in Bioengineering, National University of Singapore, Singapore
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35
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Peng ZF, Koh CHV, Li QT, Manikandan J, Melendez AJ, Tang SY, Halliwell B, Cheung NS. Deciphering the mechanism of HNE-induced apoptosis in cultured murine cortical neurons: transcriptional responses and cellular pathways. Neuropharmacology 2007; 53:687-98. [PMID: 17889908 DOI: 10.1016/j.neuropharm.2007.07.016] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 07/25/2007] [Accepted: 07/27/2007] [Indexed: 11/24/2022]
Abstract
Studies have shown that the lipid peroxidation by-product, 4-hydroxynonenal (HNE), is involved in many pathological events in several neurodegenerative diseases. A number of signaling pathways mediating HNE-induced cell death in the brain have been proposed. However, the exact mechanism remains unknown. In the present study, we have examined the effects of HNE on cultured primary cortical neurons and found that HNE treatment leads to cell death via apoptosis. Both the caspase and calpain proteolytic systems were activated. There were also increased levels of phospho-p53 and cell cycle-related proteins. Gene transcription was further studied using microarray analysis. Results showed that majority of the genes associated with cell cycle regulation, response to stress, and signal transduction were differentially expressed. The various categories of differentially-expressed genes suggested that there are other parallel pathways regulating HNE-induced neuronal apoptosis. Collectively, these might help to elucidate similar molecular mechanisms involved during cell death in neurodegenerative diseases.
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Affiliation(s)
- Zhao Feng Peng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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36
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Melendez AJ. Sphingosine kinase signalling in immune cells: potential as novel therapeutic targets. Biochim Biophys Acta 2007; 1784:66-75. [PMID: 17913601 DOI: 10.1016/j.bbapap.2007.07.013] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 07/24/2007] [Accepted: 07/25/2007] [Indexed: 12/17/2022]
Abstract
During the last few years, it has become clear that sphingolipids are sources of important signalling molecules. Particularly, the sphingolipid metabolites, ceramide and S1P, have emerged as a new class of potent bioactive molecules, implicated in a variety of cellular processes such as cell differentiation, apoptosis, and proliferation. Sphingomyelin (SM) is the major membrane sphingolipid and is the precursor for the bioactive products. Ceramide is formed from SM by the action of sphingomyelinases (SMase), however, ceramide can be very rapidly hydrolysed, by ceramidases to yield sphingosine, and sphingosine can be phosphorylated by sphingosine kinase (SphK) to yield S1P. In immune cells, the sphingolipid metabolism is tightly related to the main stages of immune cell development, differentiation, activation, and proliferation, transduced into physiological responses such as survival, calcium mobilization, cytoskeletal reorganization and chemotaxis. Several biological effectors have been shown to promote the synthesis of S1P, including growth factors, cytokines, and antigen and G-protein-coupled receptor agonists. Interest in S1P focused recently on two distinct cellular actions of this lipid, namely its function as an intracellular second messenger, capable of triggering calcium release from internal stores, and as an extracellular ligand activating specific G protein-coupled receptors. Inhibition of SphK stimulation strongly reduced or even prevented cellular events triggered by several proinflammatory agonists, such as receptor-stimulated DNA synthesis, Ca(2+) mobilization, degranulation, chemotaxis and cytokine production. Another very important observation is the direct role played by S1P in chemotaxis, and cellular escape from apoptosis. As an extracellular mediator, several studies have now shown that S1P binds a number of G-protein-coupled receptors (GPCR) encoded by endothelial differentiation genes (EDG), collectively known as the S1P-receptors. Binding of S1P to these receptors trigger an wide range of cellular responses including proliferation, enhanced extracellular matrix assembly, stimulation of adherent junctions, formation of actin stress fibres, and inhibition of apoptosis induced by either ceramide or growth factor withdrawal. Moreover, blocking S1P1-receptor inhibits lymphocyte egress from lymphatic organs. This review summarises the evidence linking SphK signalling pathway to immune-cell activation and based on these data discuss the potential for targeting SphKs to suppress inflammation and other pathological conditions.
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Affiliation(s)
- Alirio J Melendez
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
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37
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Abstract
1. RNA interference (RNAi) is a robust method of post-transcriptional silencing of genes using double-stranded RNA (dsRNA) with sequence homology driven specificity. The dsRNA can be between 21 and 23 nucleotides long: this is converted to small interfering RNA (siRNA), which then mediates gene silencing by degradation/blocking of translation of the target mRNA. 2. RNA interference provides a simple, fast and cost-effective alternative to existing gene targeting approaches both in vitro and in vivo. The discovery of siRNAs that cause RNAi in mammalian cells opened the door to the therapeutic use of siRNAs. Highly intense research efforts are now aimed at developing siRNAs for therapeutic purposes. 3. Recent advances in the design and delivery of targeting molecules now allow efficient and highly specific gene silencing in mammalian systems. Synthetic siRNA libraries targeting thousands of mammalian genes are publicly available for high-throughput genetic screens for target discovery and validation. Recent studies have demonstrated the clinical potential of aptly designed siRNAs in various types of viral infections, cancer and renal and neurodegenerative disorders. 4. The present review provides insight into the novel therapeutic strategies of siRNA technology, which is the latest development in nucleic acid-based tools for knocking down gene expression, and its potential for silencing genes associated with various human diseases.
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MESH Headings
- Amyloid Precursor Protein Secretases/genetics
- Amyloid Precursor Protein Secretases/metabolism
- Amyotrophic Lateral Sclerosis/enzymology
- Amyotrophic Lateral Sclerosis/genetics
- Animals
- Clinical Trials as Topic
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Gene Targeting/trends
- Humans
- Huntington Disease/enzymology
- Huntington Disease/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- MicroRNAs/genetics
- MicroRNAs/metabolism
- RNA Interference
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Superoxide Dismutase/genetics
- Superoxide Dismutase/metabolism
- Superoxide Dismutase-1
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Affiliation(s)
- Peter N Pushparaj
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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38
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Chen Y, Yuen WH, Fu J, Huang G, Melendez AJ, Ibrahim FBM, Lu H, Cao X. The mitochondrial respiratory chain controls intracellular calcium signaling and NFAT activity essential for heart formation in Xenopus laevis. Mol Cell Biol 2007; 27:6420-32. [PMID: 17636012 PMCID: PMC2099623 DOI: 10.1128/mcb.01946-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The mitochondrial respiratory chain (MRC) plays crucial roles in cellular energy production. However, its function in early embryonic development remains largely unknown. To address this issue, GRIM-19, a newly identified MRC complex I subunit, was knocked down in Xenopus laevis embryos. A severe deficiency in heart formation was observed, and the deficiency could be rescued by reintroducing human GRIM-19 mRNA. The mechanism involved was further investigated. We found that the activity of NFAT, a transcription factor family that contributes to early organ development, was downregulated in GRIM-19 knockdown embryos. Furthermore, the expression of a constitutively active form of mouse NFATc4 in these embryos rescued the heart developmental defects. NFAT activity is controlled by a calcium-dependent protein phosphatase, calcineurin, which suggests that calcium signaling may be disrupted by GRIM-19 knockdown. Indeed, both the calcium response and calcium-induced NFAT activity were impaired in the GRIM-19 or NDUFS3 (another complex I subunit) knockdown cell lines. We also showed that NFAT can rescue expression of Nkx2.5, which is one of the key genes for early heart development. Our data demonstrated the essential role of MRC in heart formation and revealed the signal transduction and gene expression cascade involved in this process.
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MESH Headings
- Amino Acid Sequence
- Animals
- Apoptosis Regulatory Proteins/biosynthesis
- Apoptosis Regulatory Proteins/chemistry
- Apoptosis Regulatory Proteins/genetics
- Breast Neoplasms/pathology
- Calcineurin/metabolism
- Calcium/analysis
- Calcium Signaling
- Cell Line, Tumor
- DNA, Complementary
- Electron Transport
- Embryo, Nonmammalian
- Female
- Gene Expression Regulation, Developmental
- Genes, Reporter
- HeLa Cells
- Heart/embryology
- Humans
- In Situ Hybridization
- Jurkat Cells
- Luciferases/metabolism
- Mitochondria/physiology
- Molecular Sequence Data
- Muscle, Skeletal/ultrastructure
- Myocardium/ultrastructure
- NADH, NADPH Oxidoreductases/biosynthesis
- NADH, NADPH Oxidoreductases/chemistry
- NADH, NADPH Oxidoreductases/genetics
- NFATC Transcription Factors/genetics
- NFATC Transcription Factors/metabolism
- RNA, Messenger/metabolism
- RNA, Small Interfering/metabolism
- Sequence Homology, Amino Acid
- Transcription, Genetic
- Transfection
- Xenopus laevis/embryology
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Affiliation(s)
- Yong Chen
- Signal Transduction Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, Singapore, Republic of Singapore
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39
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Melendez AJ, Jayapal M, Pushparaj PN. SIRNA KNOCKDOWN OF SPHK1 PROTECTS MICE FROM IGE-MEDIATED ANAPHYLAXIS (37.6). The Journal of Immunology 2007. [DOI: 10.4049/jimmunol.178.supp.37.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Sphingosine kinases are emerging a key enzymes in the intracellular signaling cascades, that mediate inflammatory responses, triggered by various inflammatory stimuli including: anaphylatoxins (C5a); bacterial-derived peptides (fMLP); and IgG or IgE receptor stimulation (FcγRI and FcεRI), in various immune cells, including in human mast cells. Moreover, we have recently reported a study on genome-wide gene expression profile of human mast cells sensitized with IgE alone, or stimulated by FcεRI aggregation, and found that sphingosine kinase 1 (SphK1) is one of the early genes to be activated. This, coupled to our previous studies indicating that SphK1 is pivotal in the signaling pathways initiated by FcεRI in human mast cells, prompted us to investigate the functional role of SphK1 in IgE-triggered inflammation/anaphylaxis in vivo. The systemic anaphylaxis reaction in mice has been considered to be a typical immediate hypersensitivity response determined by the activation of immune cells via antigen-induced aggregation of an IgE-sensitized FcεRI. To this end, we silenced the SPHK1 gene in vivo (using a specific siRNA), and investigated whether SphK1 knockdown influenced the outcome of the acute inflammatory responses, triggered during IgE-mediated systemic anaphylaxis in mice. We show here that, the siRNA for SphK1 protected mice from the IgE-mediated allergic reactions, including inhibition on: temperature changes; vascular permeability; immune-cell infiltration into organs; cytokine production; and vascular cell adhesion molecule expression. Thus, our findings strongly support a role for SpkK1 IgE-mediated anaphylaxis in vivo.
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Affiliation(s)
- Alirio J. Melendez
- 1Physiology, National University of Singapore, 2 Medical drive, MD9 # 01-03, Singapore, 117597, Singapore,
- 2University of Glsagow, University Avenue, Glasgow, G12 8QQ, United Kingdom
| | - Manikandan Jayapal
- 1Physiology, National University of Singapore, 2 Medical drive, MD9 # 01-03, Singapore, 117597, Singapore,
| | - Peter Natesan Pushparaj
- 1Physiology, National University of Singapore, 2 Medical drive, MD9 # 01-03, Singapore, 117597, Singapore,
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40
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Newman JPA, Banerjee B, Fang W, Poonepalli A, Balakrishnan L, Low GKM, Bhattacharjee RN, Akira S, Jayapal M, Melendez AJ, Baskar R, Lee HW, Hande MP. Short dysfunctional telomeres impair the repair of arsenite-induced oxidative damage in mouse cells. J Cell Physiol 2007; 214:796-809. [PMID: 17849448 DOI: 10.1002/jcp.21276] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Telomeres and telomerase appear to participate in the repair of broken DNA ends produced by oxidative damage. Arsenite is an environmental contaminant and a potent human carcinogen, which induces oxidative stress on cells via the generation of reactive oxygen species affecting cell viability and chromosome stability. It promotes telomere attrition and reduces cell survival by apoptosis. In this study, we used mouse embryonic fibroblasts (MEFs) from mice lacking telomerase RNA component (mTERC(-/-) mice) with long (early passage or EP) and short (late passage or LP) telomeres to investigate the extent of oxidative damage by comparing the differences in DNA damage, chromosome instability, and cell survival at 24 and 48 h of exposure to sodium arsenite (As3+; NaAsO2). There was significantly high level of DNA damage in mTERC(-/-) cells with short telomeres as determined by alkaline comet assay. Consistent with elevated DNA damage, increased micronuclei (MN) induction reflecting gross genomic instability was also observed. Fluorescence in situ hybridization (FISH) analysis revealed that increasing doses of arsenite augmented the chromosome aberrations, which contributes to genomic instability leading to possibly apoptotic cell death and cell cycle arrest. Microarray analysis has revealed that As3+ treatment altered the expression of 456 genes of which 20% of them have known functions in cell cycle and DNA damage signaling and response, cell growth, and/or maintenance. Results from our studies imply that short dysfunctional telomeres impair the repair of oxidative damage caused by arsenite. The results will have implications in risk estimation as well as cancer chemotherapy.
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Affiliation(s)
- Jennifer P A Newman
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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41
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Abstract
Immunoglobulin molecules have long been used in biomedical research as in vitro tools for identification, purification and functional manipulation of target proteins. The specificity and diversity of immunoglobulins can be exploited to target a wide range of intracellular proteins by expressing them in vivo. Such antibody molecules, which are expressed intracellularly and directed to defined sub-cellular compartments, are termed 'intrabodies'. They represent a new and versatile tool that has the potential to manipulate diverse biological processes. Gene knockout, antisense and small interfering RNA knockdown techniques, are employed to characterize the function of many gene products and to validate these gene products as potential drug targets for novel therapeutics, but they have their limitations. The experimental results to date suggest that intrabodies represent a powerful alternative to modulate protein function and analyze its effects. Moreover, they can also be utilized to target specific domains of a particular target protein. Even though their clinical application might take a long time, they can play an important role for target identification and validation in functional genomics and/or proteomics. Here we review the latest advances in the concept, construction and applications of Intrabodies.
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Affiliation(s)
- Jayapal Manikandan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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42
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Jayapal M, Tay HK, Reghunathan R, Zhi L, Chow KK, Rauff M, Melendez AJ. Genome-wide gene expression profiling of human mast cells stimulated by IgE or FcepsilonRI-aggregation reveals a complex network of genes involved in inflammatory responses. BMC Genomics 2006; 7:210. [PMID: 16911805 PMCID: PMC1564015 DOI: 10.1186/1471-2164-7-210] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 08/16/2006] [Indexed: 12/17/2022] Open
Abstract
Background Mast cells are well established effectors of IgE-triggered allergic reactions and immune responses to parasitic infections. Recent studies indicate that mast cells may play roles in adaptive and innate immunity, suggesting an innovative view of the regulation of immune responses. Here, we profiled the transcriptome of human mast cells sensitized with IgE alone, or stimulated by FcεRI aggregation. Results Our data show that among 8,793 genes examined, 559 genes are differentially regulated in stimulated mast cells when compared with resting/unstimulated mast cells. The major functional categories of upregulated genes include cytokines, chemokines, and other genes involved in innate and adaptive immune-responses. We observed the increased expression of over 63 gene-transcripts following IgE-sensitization alone. Our data was validated using Real-Time-PCR; ELISA and western blot. We confirmed that IgE alone does not trigger mast cell-immediate responses, such as calcium signals, degranulation or protein-phosphorylation. Conclusion This report represents a substantial advance in our understanding of the genome wide effects triggered by "passive sensitization" or active stimulation of human mast cells, supporting mast cells' potential involvement in a wide range of inflammatory responses.
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Affiliation(s)
| | - Hwee Kee Tay
- Department of Physiology, National University of Singapore, Singapore
| | - Renji Reghunathan
- Department of Physiology, National University of Singapore, Singapore
| | - Liang Zhi
- Department of Physiology, National University of Singapore, Singapore
| | - Kah Kiong Chow
- Department of Obstetrics & Gynecology, Gleneagles Medical Centre, Singapore
| | - Mary Rauff
- Department of Obstetrics & Gynecology, National University of Singapore, Singapore
| | - Alirio J Melendez
- Department of Physiology, National University of Singapore, Singapore
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43
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Abstract
Monocytes play an important role in inflammation, angiogenesis, and atherosclerosis. During these processes monocytes release pre-formed proinflammatory mediators from granules, and synthesize de novo cytokines and chemokines important in the amplification of the inflammatory response. One of the most prominent triggers of inflammatory responses is the cytokine TNFalpha. However, the intracellular signaling cascades triggered by TNFalpha are not fully understood. In this study we investigated the roles of SPHK on the TNFalpha-triggered responses on human primary monocytes. We show that TNFalpha rapidly triggers S1P generation and activation of SPHK. Moreover, our data shows that SPHK1 is the isoform activated by TNFalpha, and plays an essential role on the TNFalpha-triggered intracellular Ca2+ signals, degranulation, cytokine production, and activation of NFkappaB, thus suggesting a pivotal role for SPHK1 on the proinflammatory responses triggered by TNFalpha.
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Affiliation(s)
- Liang Zhi
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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44
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45
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Abstract
1. Microarrays, a recent development, provide a revolutionary platform to analyse thousands of genes at once. They have enormous potential in the study of biological processes in health and disease and, perhaps, microarrays have become crucial tools in diagnostic applications and drug discovery. 2. Microarray based studies have provided the essential impetus for biomedical experiments, such as identification of disease-causing genes in malignancies and regulatory genes in the cell cycle mechanism. Microarrays can identify genes for new and unique potential drug targets, predict drug responsiveness for individual patients and, finally, initiate gene therapy and prevention strategies. 3. The present article reviews the principles and technological concerns, as well as the steps involved in obtaining and analysing of data. Furthermore, applications of microarray based experiments in drug target identifications and validation strategies are discussed. 4. To exemplify how this tool can be useful, in the present review we provide an overview of some of the past and potential future aspects of microarray technology and present a broad overview of this rapidly growing field.
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Affiliation(s)
- Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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46
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Liu H, Kemeny DM, Heng BC, Ouyang HW, Melendez AJ, Cao T. The Immunogenicity and Immunomodulatory Function of Osteogenic Cells Differentiated from Mesenchymal Stem Cells. J Immunol 2006; 176:2864-71. [PMID: 16493043 DOI: 10.4049/jimmunol.176.5.2864] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Multipotent mesenchymal stem cells (MSC) are reported to be immunoprivileged as well as immunosuppressive. Hence, they are ideal candidates for allogeneic transplantation to induce regeneration of diseased tissues and organs. However, it is not known whether MSC would retain their immunoprivileged and immunomodulatory properties after differentiating into the local cell types of the transplantation site. This study sought to investigate this question with a novel New Zealand White rabbit osteogenesis model. Results showed that osteogenic cells differentiated from MSC (DOC) in vitro did not express the MHC class II molecule, were incapable of inducing allogeneic lymphocyte proliferation in mixed lymphocyte culture or generating CTL, were inhibitory in ongoing lymphocyte proliferation, and secreted anti-inflammatory cytokines (IL-10 and TGF-beta). There was a significantly higher secretion of IL-10 by DOC than that by MSC, while there was no significant difference between the TGF-beta secretion of MSC and DOC in vitro. However, after IFN-gamma treatment, TGF-beta secretion by DOC significantly decreased despite the increased production by MSC. Four weeks after local DOC implantation, despite MHC class II expression, second-set allogeneic skin rejection showed similar survival to first-set allogeneic skin rejection and DOC appeared to function as osteoblasts. In conclusion, DOC retained their immunoprivileged and immunomodulatory properties in vitro, but the latter was lost following transplantation.
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Affiliation(s)
- Hua Liu
- Stem Cell Laboratory, Faculty of Dentistry, National University of Singapore, Singapore
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47
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Vlasenko LP, Melendez AJ. A critical role for sphingosine kinase in anaphylatoxin-induced neutropenia, peritonitis, and cytokine production in vivo. J Immunol 2005; 174:6456-61. [PMID: 15879148 DOI: 10.4049/jimmunol.174.10.6456] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aim of our study was to investigate the roles played by sphingosine kinase (SPHK) in the anaphylatoxin C5a-triggered responses in vivo. Our data show that i.v. administration of C5a triggers a rapid neutropenic response, but pretreating mice with the SPHK inhibitor, N,N-dimethylsphingosine (DMS), 10 min before the C5a i.v. administration substantially inhibited the C5a-triggered neutropenia. Similarly the i.v. administration of C5a caused a rapid increase in the serum levels of TNF-alpha and IL-6, and this increase in cytokine levels was blocked by DMS. We then induced acute peritonitis with C5a. The C5a i.p. injection triggered a fast recruitment of neutrophils, later followed by monocytes, into the peritoneal cavity. Vascular permeability was also observed: when we i.v. injected Evans blue before C5a i.p. injection, we could observe a continued influx of the dye into the peritoneum. In mice pretreated with DMS, there was a significant reduction on the C5a-triggered neutrophil and monocyte infiltration, as well as a marked reduction on the Evans blue influx. Our data also show that the i.p. administration of C5a caused a rapid increase in TNF-alpha and IL-6 levels in the peritoneal cavity, and this increase in cytokine levels was substantially inhibited in mice pretreated with the SPHK inhibitor. Taken together, these observations suggest a potential role for SPHK in the C5a-triggered inflammatory responses in vivo.
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48
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Yew EHJ, Cheung NS, Choy MS, Qi RZ, Lee AYW, Peng ZF, Melendez AJ, Manikandan J, Koay ESC, Chiu LL, Ng WL, Whiteman M, Kandiah J, Halliwell B. Proteasome inhibition by lactacystin in primary neuronal cells induces both potentially neuroprotective and pro-apoptotic transcriptional responses: a microarray analysis. J Neurochem 2005; 94:943-56. [PMID: 15992382 DOI: 10.1111/j.1471-4159.2005.03220.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Although inhibition of the ubiquitin proteasome system has been postulated to play a key role in the pathogenesis of neurodegenerative diseases, studies have also shown that proteasome inhibition can induce increased expression of neuroprotective heat-shock proteins (HSPs). The global gene expression of primary neurons in response to treatment with the proteasome inhibitor lactacystin was studied to identify the widest range of possible pathways affected. Our results showed changes in mRNA abundance, both at different time points after lactacystin treatment and at different lactacystin concentrations. Genes that were differentially up-regulated at the early time point but not when most cells were undergoing apoptosis might be involved in an attempt to reverse proteasome inhibitor-mediated apoptosis and include HSP70, HSP22 and cell cycle inhibitors. The up-regulation of HSP70 and HSP22 appeared specific towards proteasome inhibitor-mediated cell death. Overexpression of HSP22 was found to protect against proteasome inhibitor-mediated loss of viability by up to 25%. Genes involved in oxidative stress and the inflammatory response were also up-regulated. These data suggest an initial neuroprotective pathway involving HSPs, antioxidants and cell cycle inhibitors, followed by a pro-apoptotic response possibly mediated by inflammation, oxidative stress and aberrant activation of cell cycle proteins.
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Affiliation(s)
- Elaine Hau Jin Yew
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore
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49
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Abstract
1. Sphingolipids are potent second messengers modulating biochemical intracellular events and acting as ligands to mediate extracellular systems. Sphingosine kinase (SPHK) is the enzyme that phosphorylates sphingosine into sphingosine-1-phosphate (S1P), a potent bioactive sphingolipid. 2. The fact that SPHK is highly conserved from protozoa to mammals and is ubiquitous in living tissues reveals important roles of the SPHK pathway for the maintenance of health maintenance. This is also supported by comprehensive reviews on features of its main product, S1P, as having intracellular as well as extracellular roles, inducing a wide range of physiological responses from triggering Ca2+ release from internal stores to promoting growth and cell motility. 3. Immune cell activities have been shown to be modulated by the dynamic balance between ceramide, sphingosine and S1P, conceptualized as a rheostat. Cell proliferation, differentiation, motility and survival have been attributed to the regulatory actions of S1P. The properties of SPHK activity in immune cells are linked to the functions of triggered growth and survival factors, phorbol esters, hormones, cytokines and chemokines, as well as antigen receptors, such as FcgammaRI and FcepsilonRI. 4. Mechanisms of the SPHK signalling pathway are explored as new targets for drug development to suppress inflammation and other pathological conditions.
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Affiliation(s)
- Tay Hwee Kee
- Department of Physiology, Faculty of Medicine, National University of Singapore, Singapore
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50
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Melendez AJ, Ibrahim FBM. Antisense knockdown of sphingosine kinase 1 in human macrophages inhibits C5a receptor-dependent signal transduction, Ca2+ signals, enzyme release, cytokine production, and chemotaxis. J Immunol 2004; 173:1596-603. [PMID: 15265887 DOI: 10.4049/jimmunol.173.3.1596] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The anaphylatoxin C5a is produced following the activation of the complement system and is associated with a variety of pathologies, including septic shock and adult respiratory distress syndrome, and with immune complex-dependent diseases such as rheumatoid arthritis. C5a has been shown to regulate inflammatory functions by interacting with its receptor, C5aR, which belong to the rhodopsin family of seven-transmembrane GPCRs. However, the intracellular signaling pathways triggered by C5aR on immune-effector cells are not well understood. In this report we present data showing that, in human monocyte-derived macrophages, C5aR uses the intracellular signaling molecule sphingosine kinase (SPHK)1 to trigger various physiological responses. Our data show that C5a rapidly stimulates the generation of sphingosine-1-phosphate, SPHK activity, and membrane translocation of SPHK1. Using an antisense oligonucleotide against SPHK1, we show that knockdown of SPHK1 abolishes the C5a-triggered intracellular Ca(2+) signals, degranulation, cytokine generation, and chemotaxis. Our study shows for the first time that SPHK1 not only plays a key role in the generation and release of proinflammatory mediators triggered by anaphylatoxins from human macrophages but is also involved in the process of immune cell motility, thus pointing out SPHK1 as a potential therapeutic target for the treatment of inflammatory and autoimmune diseases.
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Affiliation(s)
- Alirio J Melendez
- Department of Physiology, National University of Singapore, Singapore.
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