TRPM2 channel opening in response to oxidative stress is dependent on activation of poly(ADP-ribose) polymerase (original) (raw)
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Cellular Signalling, 2013
The transient receptor potential melastatin (TRPM) protein family is an extensive group of ion channels expressed in several types of mammalian cells. Many studies have shown that these channels are crucial for performing several physiological functions. Additionally, a large body of evidence indicates that these channels are also involved in numerous human diseases, known as channelopathies. A characteristic event frequently observed during pathological states is the raising in intracellular oxidative agents over reducing molecules, shifting the redox balance and inducing oxidative stress. In particular, three members of the TRPM subfamily, TRPM2, TRPM4 and TRPM7, share the remarkable feature that their activities are modulated by oxidative stress. Because of the increase in oxidative stress, these TRPM channels function aberrantly, promoting the onset and development of diseases. Increases, absences, or modifications in the function of these redox-modulated TRPM channels are associated with cell dysfunction and human pathologies. Therefore, the effect of oxidative stress on ion channels becomes an essential part of the pathogenic mechanism. Thus, oxidative stress-modulated ion channels are more susceptible to generating pathological states than oxidant-independent channels. This review examines the most relevant findings regarding the participation of the oxidative stress-modulated TRPM ion channels, TRPM2, TRPM4, and TRPM7, in human diseases. In addition, the potential roles of these channels as therapeutic tools and targets for drug design are discussed.
Role of TRPM2 in cell proliferation and susceptibility to oxidative stress
American Journal of Physiology-Cell Physiology, 2013
The transient receptor potential (TRP) channel TRPM2 is an ion channel that modulates cell survival. We report here that full-length (TRPM2-L) and short (TRPM2-S) isoform expression was significantly increased in human neuroblastoma compared with adrenal gland. To differentiate the roles of TRPM2-L and TRPM2-S in cell proliferation and survival, we established neuroblastoma SH-SY5Y cell lines stably expressing either TRPM2 isoform or empty vector. Cells expressing TRPM2-S showed significantly enhanced proliferation, downregulation of phosphatase and tensin homolog (PTEN), and increased protein kinase B (Akt) phosphorylation and cell surface glucose transporter 1 (Glut1) compared with cells expressing TRPM2-L or empty vector. ERK phosphorylation was increased, and forkhead box O 3a (FOXO3a) levels were decreased. Inhibitor studies demonstrated that enhanced proliferation was dependent on phosphatidylinositol 3-kinase/Akt, ERK, and NADPH oxidase activation. On the other hand, TRPM2-S-...
Role of TRPM2 in H2O2-Induced Cell Apoptosis in Endothelial Cells
PLoS ONE, 2012
Melastatin-like transient receptor potential channel 2 (TRPM2) is an oxidant-sensitive and cationic non-selective channel that is expressed in mammalian vascular endothelium. Here we investigated the functional role of TRPM2 channels in hydrogen peroxide (H 2 O 2)-induced cytosolic Ca 2+ ([Ca 2+ ] i) elavation, whole-cell current increase, and apoptotic cell death in murine heart microvessel endothelial cell line H5V. A TRPM2 blocking antibody (TM2E3), which targets the E3 region near the ion permeation pore of TRPM2, was developed. Treatment of H5V cells with TM2E3 reduced the [Ca 2+ ] i rise and whole-cell current change in response to H 2 O 2. Suppressing TRPM2 expression using TRPM2-specific short hairpin RNA (shRNA) had similar inhibitory effect. H 2 O 2-induced apoptotic cell death in H5V cells was examined using MTT assay, DNA ladder formation analysis, and DAPI-based nuclear DNA condensation assay. Based on these assays, TM2E3 and TRPM2-specific shRNA both showed protective effect against H 2 O 2-induced apoptotic cell death. TM2E3 and TRPM2-specific shRNA also protect the cells from tumor necrosis factor (TNF)-a-induced cell death in MTT assay. In contrast, overexpression of TRPM2 in H5V cells resulted in an increased response in [Ca 2+ ] i and whole-cell currents to H 2 O 2. TRPM2 overexpression also aggravated the H 2 O 2-induced apoptotic cell death. Downstream pathways following TRPM2 activation was examined. Results showed that TRPM2 activity stimulated caspase-8, caspase-9 and caspase-3. These findings strongly suggest that TRPM2 channel mediates cellular Ca 2+ overload in response to H 2 O 2 and contribute to oxidant-induced apoptotic cell death in vascular endothelial cells. Down-regulating endogenous TRPM2 could be a means to protect the vascular endothelial cells from apoptotic cell death.
TRPM2 Non-Selective Cation Channels in Liver Injury Mediated by Reactive Oxygen Species
Antioxidants, 2021
TRPM2 channels admit Ca2+ and Na+ across the plasma membrane and release Ca2+ and Zn2+ from lysosomes. Channel activation is initiated by reactive oxygen species (ROS), leading to a subsequent increase in ADP-ribose and the binding of ADP-ribose to an allosteric site in the cytosolic NUDT9 homology domain. In many animal cell types, Ca2+ entry via TRPM2 channels mediates ROS-initiated cell injury and death. The aim of this review is to summarise the current knowledge of the roles of TRPM2 and Ca2+ in the initiation and progression of chronic liver diseases and acute liver injury. Studies to date provide evidence that TRPM2-mediated Ca2+ entry contributes to drug-induced liver toxicity, ischemia–reperfusion injury, and the progression of non-alcoholic fatty liver disease to cirrhosis, fibrosis, and hepatocellular carcinoma. Of particular current interest are the steps involved in the activation of TRPM2 in hepatocytes following an increase in ROS, the downstream pathways activated by...
Another TRP to Endothelial Dysfunction TRPM2 and Endothelial Permeability
2008
T he vascular endothelium acts not only as a passive barrier between plasma and extracellular fluid but is intimately involved in various physiological processes including the regulation of systemic and regional vascular tone, blood coagulation, cell-cell adhesion, wound healing, cellular proliferation, and angiogenesis. The implications of endothelial dysfunction in many pathological states have rendered modulation of endothelial functions as a promising therapeutic strategy for cardiovascular and cerebrovascular disease. Increasing endothelial permeability by oxidative stress through the production of oxygen metabolites is an important trigger for endothelial dysfunction.
American Journal of Physiology-Cell Physiology, 2005
TRPM2 is a Ca2+-permeable channel activated by oxidative stress or TNF-α, and TRPM2 activation confers susceptibility to cell death. The mechanisms were examined here in human monocytic U937-ecoR cells. This cell line expresses full-length TRPM2 (TRPM2-L) and several isoforms including a short splice variant lacking the Ca2+-permeable pore region (TRPM2-S), which functions as a dominant negative. Treatment with H2O2, a model of oxidative stress, or TNF-α results in reduced cell viability. Expression of TRPM2-L and TRPM2-S was modulated by retroviral infection. U937-ecoR cells expressing increased levels of TRPM2-L were treated with H2O2or TNF-α, and these cells exhibited significantly increased intracellular calcium concentration ([Ca2+]i), decreased viability, and increased apoptosis. A dramatic increase in cleavage of caspases-8, -9, -3, and -7 and poly(ADP-ribose)polymerase (PARP) was observed, demonstrating a downstream mechanism through which cell death is mediated. Bcl-2 level...
Journal of Cellular and Molecular Medicine, 2009
2ϩ -permeable channel activated by hydrogen peroxide (H2O2). We have investigated the role of TRPM2 channels in mediating the H2O2-induced increase in the cytoplasmic free Ca 2ϩ concentration ([Ca 2ϩ ]i) in insulin-secreting cells. In fura-2 loaded INS-1E cells, a widely used model of -cells, and in human -cells, H2O2 increased [Ca 2ϩ ]i, in the presence of 3 mM glucose, by inducing Ca 2ϩ influx across the plasma membrane. H2O2-induced Ca 2ϩ influx was not blocked by nimodipine, a blocker of the L-type voltage-gated Ca 2ϩ channels nor by 2-aminoethoxydiphenyl borate, a blocker of several TRP channels and store-operated channels, but it was completely blocked by N-(p-amylcinnamoyl)anthranilic acid (ACA), a potent inhibitor of TRPM2. Adenosine diphosphate phosphate ribose, a specific activator of TRPM2 channel and H2O2, induced inward cation currents that were blocked by ACA. Western blot using antibodies directed to the epitopes on the N-terminal and on the C-terminal parts of TRPM2 identified the full length TRPM2 (TRPM2-L), and the C-terminally truncated TRPM2 (TRPM2-S) in human islets. We conclude that functional TRPM2 channels mediate H2O2-induced Ca 2ϩ entry in -cells, a process potently inhibited by ACA.
Inhibition of TRPM2 cation channels by N -(p -amylcinnamoyl)anthranilic acid
British Journal of Pharmacology, 2009
TRPM2 is a Ca 2 þ-permeable nonselective cation channel activated by intracellular ADP-ribose (ADPR) and by hydrogen peroxide (H 2 O 2). We investigated the modulation of TRPM2 activity by N-(p-amylcinnamoyl)anthranilic acid (ACA). ACA has previously been reported to inhibit phospholipase A 2 (PLA 2). 2 Using patch-clamp and calcium-imaging techniques, we show that extracellular application of 20 mM ACA completely blocked ADPR-induced whole-cell currents and H 2 O 2-induced Ca 2 þ signals (IC 50 ¼ 1.7 mM) in HEK293 cells transfected with human TRPM2. Two other PLA 2 inhibitors, p-bromophenacyl bromide (BPB; 100 mM) and arachidonyl trifluoromethyl ketone (20 mM), had no significant effect on ADPR-stimulated TRPM2 activity. 3 Inhibition of TRPM2 whole-cell currents by ACA was voltage independent and accelerated at decreased pH. ACA was ineffective when applied intracellularly. The single-channel conductance was not changed during ACA treatment, suggesting a reduction of TRPM2 open probability by modulating channel gating. 4 ACA (20 mM) also blocked currents through human TRPM8 and TRPC6 expressed in HEK293 cells, while BPB (100 mM) was ineffective. TRPC6-mediated currents (IC 50 ¼ 2.3 mM) and TRPM8induced Ca 2 þ signals (IC 50 ¼ 3.9 mM) were blocked in a concentration-dependent manner. 5 ADPR-induced currents in human U937 cells, endogeneously expressing TRPM2 protein, were fully suppressed by 20 mM ACA. 6 Our data indicate that ACA modulates the activity of different TRP channels independent of PLA 2 inhibition. Owing to its high potency and efficacy ACA can serve, in combination with other blockers, as a useful tool for studying the unknown function of TRPM2 in native cells.
TRPM2: a multifunctional ion channel for calcium signalling
Journal of Physiology-London, 2011
The transient potential receptor melastatin-2 (TRPM2) channel has emerged as an important Ca 2+ signalling mechanism in a variety of cells, contributing to cellular functions that include cytokine production, insulin release, cell motility and cell death. Its ability to respond to reactive oxygen species has made TRPM2 a potential therapeutic target for chronic inflammation, neurodegenerative diseases, and oxidative stress-related pathologies. TRPM2 is a non-selective, calcium (Ca 2+)-permeable cation channel of the melastatin-related transient receptor potential (TRPM) ion channel subfamily. It is activated by intracellular adenosine diphosphate ribose (ADPR) through a diphosphoribose hydrolase domain in its C-terminus and regulated through a variety of factors, including synergistic facilitation by [Ca 2+ ] i , cyclic ADPR, H 2 O 2 , NAADP, and negative feedback regulation by AMP and permeating protons (pH). In addition to its role mediating Ca 2+ influx into the cells, TRPM2 can also function as a lysosomal Ca 2+ release channel, contributing to cell death. The physiological and pathophysiological context of ROS-mediated events makes TRPM2 a promising target for the development of therapeutic tools of inflammatory and degenerative diseases.