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Abstract
Natural product ligands have contributed significantly to the deorphanisation of TRP ion channels. Furthermore, natural product ligands continue to provide valuable leads for the identification of ligands acting at "orphan" TRP channels. Additional naturally occurring modulators at TRP channels can be expected to be discovered in future, aiding in our understanding of not only their pharmacology and physiology, but also the therapeutic potential of this fascinating family of ion channels.
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402
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TRP channels in the cardiopulmonary vasculature. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:781-810. [PMID: 21290327 DOI: 10.1007/978-94-007-0265-3_41] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transient receptor potential (TRP) channels are expressed in almost every human tissue, including the heart and the vasculature. They play unique roles not only in physiological functions but, if over-expressed, also in pathophysiological disease states. Cardiovascular diseases are the leading cause of death in the industrialized countries. Therefore, TRP channels are attractive drug targets for more effective pharmacological treatments of these diseases. This review focuses on three major cell types of the cardiovascular system: cardiomyocytes as well as smooth muscle cells and endothelial cells from the systemic and pulmonary circulation. TRP channels initiate multiple signals in all three cell types (e.g. contraction, migration) and are involved in gene transcription leading to cell proliferation or cell death. Identification of their genes has significantly improved our knowledge of multiple signal transduction pathways in these cells. Some TRP channels are important cellular sensors and are mostly permeable to Ca(2+), while most other TRP channels are receptor activated and allow for the entry of Na(+), Ca(2+) and Mg(2+). Physiological functions of TRPA, TRPC, TRPM, TRPP and TRPV channels in the cardiovascular system, dissected by down-regulating channel activity in isolated tissues or by the analysis of gene-deficient mouse models, are reviewed. The involvement of TRPs as homomeric or heteromeric channels in pathophysiological processes in the cardiovascular system like heart failure, cardiac hypertrophy, hypertension as well as edema formation by increased endothelial permeability will be discussed.
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403
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Miller BA, Zhang W. TRP Channels as Mediators of Oxidative Stress. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:531-44. [DOI: 10.1007/978-94-007-0265-3_29] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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404
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Transient Receptor Potential Cation Channels in Pancreatic β Cells. Rev Physiol Biochem Pharmacol 2011; 161:87-110. [DOI: 10.1007/112_2011_2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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405
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Expression and function of TRP channels in liver cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:667-86. [PMID: 21290321 DOI: 10.1007/978-94-007-0265-3_35] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The liver plays a central role in whole body homeostasis by mediating the metabolism of carbohydrates, fats, proteins, drugs and xenobiotic compounds, and bile acid and protein secretion. Hepatocytes together with endothelial cells, Kupffer cells, smooth muscle cells, stellate and oval cells comprise the functioning liver. Many members of the TRP family of proteins are expressed in hepatocytes. However, knowledge of their cellular functions is limited. There is some evidence which suggests the involvement of TRPC1 in volume control, TRPV1 and V4 in cell migration, TRPC6 and TRPM7 in cell proliferation, and TRPPM in lysosomal Ca(2+) release. Altered expression of some TRP proteins, including TRPC6, TRPM2 and TRPV1, in tumorigenic cell lines may play roles in the development and progression of hepatocellular carcinoma and metastatic liver cancers. It is likely that future experiments will define important roles for other TRP proteins in the cellular functions of hepatocytes and other cell types of which the liver is composed.
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406
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Harteneck C, Klose C, Krautwurst D. Synthetic modulators of TRP channel activity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:87-106. [PMID: 21290290 DOI: 10.1007/978-94-007-0265-3_4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In humans, 27 TRP channels from 6 related families contribute to a broad spectrum of cellular functions, such as thermo-, pressure-, volume-, pain- and chemosensation. Pain and inflammation-inducing compounds represent potent plant and animal defense mechanisms explaining the great variety of the naturally occurring, TRPV1-, TRPM8-, and TRPA1-activating ligands. The discovery of the first vanilloid receptor (TRPV1) and its involvement in nociception triggered the euphoria and the hope in novel therapeutic strategies treating pain, and this clear-cut indication inspired the development of TRPV1-selective ligands. On the other hand the nescience in the physiological role and putative clinical indication hampered the development of a selective drug in the case of the other TRP channels. Therefore, currently only a handful of mostly un-selective blocker is available to target TRP channels. Nevertheless, there is an ongoing quest for new, natural or synthetic ligands and modulators. In this chapter, we will give an overview on available broad-range blocker, as well as first TRP channel-selective compounds.
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Affiliation(s)
- Christian Harteneck
- Institute for Pharmacology and Toxicology, Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICEPHA), Eberhard-Karls-University, Tübingen, Germany.
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407
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Uchida K, Tominaga M. The role of thermosensitive TRP (transient receptor potential) channels in insulin secretion. Endocr J 2011; 58:1021-8. [PMID: 21785227 DOI: 10.1507/endocrj.ej11-0130] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin secretion from pancreatic β-cells is the only efficient means to decrease blood glucose concentrations. Glucose is the principal stimulator of insulin secretion with the ATP-sensitive K+ channel-voltage-gated Ca2+ channel-mediated pathway being the primary one involved in glucose-stimulated insulin secretion. Recently, several reports demonstrated that some transient receptor potential (TRP) channels are expressed in pancreatic β-cells and contribute to pancreatic β-cell functions. Interestingly, six of them (TRPM2, TRPM4, TRPM5, TRPV1, TRPV2 and TRPV4) are thermosensitive TRP channels. Thermosensitive TRP channels in pancreatic β-cells can function as multimodal receptors and cause Ca2+ influx and membrane depolarization at physiological body temperature. TRPM channels (TRPM2, TRPM4 and TRPM5) control insulin secretion levels by sensing intracellular Ca2+ increase, NAD metabolites, or hormone receptor activation. TRPV2 is involved not only in insulin secretion but also cell proliferation, and is regulated by the autocrine effects of insulin. TRPV1 expressed in sensory neurons is involved in β-cell stress and islet inflammation by controlling neuropeptide release levels. It is thus clear that thermosensitive TRP channels play important roles in pancreatic β-cell functions, and future analyses of TRP channel function will lead to better understanding of the complicated mechanisms involved in insulin secretion and diabetes pathogenesis.
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Affiliation(s)
- Kunitoshi Uchida
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Aichi 444-8787 Japan.
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408
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Uchida K, Dezaki K, Damdindorj B, Inada H, Shiuchi T, Mori Y, Yada T, Minokoshi Y, Tominaga M. Lack of TRPM2 impaired insulin secretion and glucose metabolisms in mice. Diabetes 2011; 60:119-26. [PMID: 20921208 PMCID: PMC3012163 DOI: 10.2337/db10-0276] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE TRPM2 is a Ca²(+)-permeable nonselective cation channel activated by adenosine dinucleotides. We previously demonstrated that TRPM2 is activated by coapplication of heat and intracellular cyclic adenosine 5'-diphosphoribose, which has been suggested to be involved in intracellular Ca²(+) increase in immunocytes and pancreatic β-cells. To clarify the involvement of TRPM2 in insulin secretion, we analyzed TRPM2 knockout (TRPM2-KO) mice. RESEARCH DESIGN AND METHODS Oral and intraperitoneal glucose tolerance tests (OGTT and IPGTT) were performed in TRPM2-KO and wild-type mice. We also measured cytosolic free Ca²(+) in single pancreatic cells using fura-2 microfluorometry and insulin secretion from pancreatic islets. RESULTS Basal blood glucose levels were higher in TRPM2-KO mice than in wild-type mice without any difference in plasma insulin levels. The OGTT and IPGTT demonstrated that blood glucose levels in TRPM2-KO mice were higher than those in wild-type mice, which was associated with an impairment in insulin secretion. In isolated β-cells, smaller intracellular Ca²(+) increase was observed in response to high concentrations of glucose and incretin hormone in TRPM2-KO cells than in wild-type cells. Moreover, insulin secretion from the islets of TRPM2-KO mice in response to glucose and incretin hormone treatment was impaired, whereas the response to tolbutamide, an ATP-sensitive potassium channel inhibitor, was not different between the two groups. CONCLUSIONS These results indicate that TRPM2 is involved in insulin secretion stimulated by glucose and that further potentiated by incretins. Thus, TRPM2 may be a new target for diabetes therapy.
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Affiliation(s)
- Kunitoshi Uchida
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Katsuya Dezaki
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Boldbaatar Damdindorj
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Hitoshi Inada
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Japan
| | - Tetsuya Shiuchi
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
- Department of Developmental Physiology, Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yasuhiko Minokoshi
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Okazaki, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
- Corresponding author: Makoto Tominaga,
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409
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Binshtok AM. Mechanisms of nociceptive transduction and transmission: a machinery for pain sensation and tools for selective analgesia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 97:143-77. [PMID: 21708310 DOI: 10.1016/b978-0-12-385198-7.00006-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many surgical and dental procedures depend on use of local anesthetics to reversibly eliminate pain. By the blockade of voltage-gated sodium channels, local anesthetics prevent the transmission of nociceptive information. However, since all local anesthetics act non-selectively on all types of axons they also cause a loss of innocuous sensation, motor paralysis and autonomic block. Thus, approaches that produce only a selective blockade of pain fibers are of great potential clinical importance. In this chapter we will review the recent findings describing mechanisms of pain transduction and transmission and introduce novel therapeutic approaches to produce pain-selective analgesia.
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Affiliation(s)
- Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada and Center for Research on Pain, The Hebrew University Medical School, Jerusalem, Israel
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410
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Mori Y, Kajimoto T, Nakao A, Takahashi N, Kiyonaka S. Receptor Signaling Integration by TRP Channelsomes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:373-89. [DOI: 10.1007/978-94-007-0265-3_21] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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411
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Sunesen M, Jacobsen RB. Study of TRP Channels by Automated Patch Clamp Systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 704:107-23. [DOI: 10.1007/978-94-007-0265-3_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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412
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Nazıroğlu M. TRPM2 cation channels, oxidative stress and neurological diseases: where are we now? Neurochem Res 2010; 36:355-66. [PMID: 21140288 DOI: 10.1007/s11064-010-0347-4] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2010] [Indexed: 12/13/2022]
Abstract
The Na+ and Ca(2+)-permeable melastatin related transient receptor potential 2 (TRPM2) channels can be gated either by ADP-ribose (ADPR) in concert with Ca(2+) or by hydrogen peroxide (H(2)O(2)), an experimental model for oxidative stress, binding to the channel's enzymatic Nudix domain. Since the mechanisms that lead to TRPM2 gating in response to ADPR and H(2)O(2) are not understood in neuronal cells, I summarized previous findings and important recent advances in the understanding of Ca(2+) influx via TRPM2 channels in different neuronal cell types and disease processes. Considering that TRPM2 is activated by oxidative stress, mediated cell death and inflammation, and is highly expressed in brain, the channel has been investigated in the context of central nervous system. TRPM2 plays a role in H(2)O(2) and amyloid β-peptide induced striatal cell death. Genetic variants of the TRPM2 gene confer a risk of developing Western Pacific amyotropic lateral sclerosis and parkinsonism-dementia complex and bipolar disorders. TRPM2 also contributes to traumatic brain injury processes such as oxidative stress, inflammation and neuronal death. There are a limited number of TRPM2 channel blockers and they seem to be cell specific. For example, ADPR-induced Ca(2+) influx in rat hippocampal cells was not blocked by N-(p-amylcinnomoyl)anthralic acid (ACA), the IP(3) receptor inhibitor 2-aminoethoxydiphenyl borate or PLC inhibitor flufenamic acid (FFA). However, the Ca(2+) entry in rat primary striatal cells was blocked by ACA and FFA. In conclusion TRPM2 channels in neuronal cells can be gated by either ADPR or H(2)O(2). It seems to that the exact relationship between TRPM2 channels activation and neuronal cell death still remains to be determined.
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Affiliation(s)
- Mustafa Nazıroğlu
- Neuroscience Research Center, Süleyman Demirel University, Isparta, Turkey.
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413
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Yogi A, Callera GE, Antunes TT, Tostes RC, Touyz RM. Transient receptor potential melastatin 7 (TRPM7) cation channels, magnesium and the vascular system in hypertension. Circ J 2010; 75:237-45. [PMID: 21150127 DOI: 10.1253/circj.cj-10-1021] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Decreased Mg(2+) concentration has been implicated in altered vascular reactivity, endothelial dysfunction and structural remodeling, processes important in vascular changes and target organ damage associated with hypertension. Unlike our knowledge of other major cations, mechanisms regulating cellular Mg(2+) handling are poorly understood. Until recently little was known about protein transporters controlling transmembrane Mg(2+) influx. However, new research has uncovered a number of genes and proteins identified as transmembrane Mg(2+) transporters, particularly transient receptor potential melastatin (TRPM) cation channels, TRPM6 and TRPM7. Whereas TRPM6 is found primarily in epithelial cells, TRPM7 is ubiquitously expressed. Vascular TRPM7 has been implicated as a signaling kinase involved in vascular smooth muscle cell growth, apoptosis, adhesion, contraction, cytoskeletal organization and migration, and is modulated by vasoactive agents, pressure, stretch and osmotic changes. Emerging evidence suggests that vascular TRPM7 function might be altered in hypertension. The present review discusses the importance of Mg(2+) in vascular biology in hypertension and focuses on transport systems, mainly TRPM7, that might play a role in the control of vascular Mg(2+) homeostasis. Elucidation of the relationship between the complex systems responsible for regulation of Mg(2+) homeostasis, the role of TRPM7 in vascular signaling, and the cardiovascular impact will be important for understanding the clinical implications of hypomagnesemia in cardiovascular disease.
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Affiliation(s)
- Alvaro Yogi
- Kidney Research Center, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada
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414
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Abstract
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.
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Affiliation(s)
- Adriana Sumoza-Toledo
- Center for Biomedical Research, The Queen's Medical Center, University of Hawaii, 1301 Punchbowl Street - UHT 8, HI 96813, USA
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415
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Gao Y, Lei Z, Lu C, Roisen FJ, El-Mallakh RS. Effect of ionic stress on apoptosis and the expression of TRPM2 in human olfactory neuroepithelial-derived progenitors. World J Biol Psychiatry 2010; 11:972-84. [PMID: 20799912 DOI: 10.3109/15622975.2010.507784] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVES Disturbed ion homeostasis and apoptosis have been implicated in the pathophysiology of bipolar disorder (BD). TRPM2, a nonselective cation channel, is involved in apoptosis and is possibly linked with BD. In this study, monensin, a sodium ionophore, was used to model the increase [Na(+)](in) and [Ca(2+)](in) seen in BD patients. METHODS Human olfactory neuroepithelial-derived progenitors (ONP), which possess neuronal markers, were utilized to investigate the effects of monensin on apoptosis and the response of TRPM2, and the effects of lithium on the cellular response to monensin. Monensin treatment for 6 h activated caspase-3, -7 and poly(ADP-ribose) polymerase (PARP), inducing apoptosis. RESULTS [Na(+)](in) increased to twice the basal level and reached steady state after 2 h of 10(-6) M monensin treatment, while [Ca(2+)](in) rose after 6 h of the treatment. Monensin treatment for 24 h decreased expression of the long form of TRPM2, and increased expression of the short form. Lithium (1 mM) pretreatment reduced the [Na(+)](in) and [Ca(2+)](in) elevation caused by monensin, down-regulated the levels of caspase-3, -7 and PARP, and reduced expression of TRPM2. CONCLUSIONS Our findings suggest that the elevation of [Na(+)](in) and [Ca(2+)](in) induced ONP apoptosis and altered the expression of TRPM2. Lithium pretreatment attenuated the apoptosis induced by ionic stress.
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Affiliation(s)
- Yonglin Gao
- Department of Psychiatry and Behavioral Sciences, University of Louisville, School of Medicine, Louisville, KY 40292, USA
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416
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Wu LJ, Sweet TB, Clapham DE. International Union of Basic and Clinical Pharmacology. LXXVI. Current progress in the mammalian TRP ion channel family. Pharmacol Rev 2010; 62:381-404. [PMID: 20716668 DOI: 10.1124/pr.110.002725] [Citation(s) in RCA: 426] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential (TRP) channels are a large family of ion channel proteins, surpassed in number in mammals only by voltage-gated potassium channels. TRP channels are activated and regulated through strikingly diverse mechanisms, making them suitable candidates for cellular sensors. They respond to environmental stimuli such as temperature, pH, osmolarity, pheromones, taste, and plant compounds, and intracellular stimuli such as Ca(2+) and phosphatidylinositol signal transduction pathways. However, it is still largely unknown how TRP channels are activated in vivo. Despite the uncertainties, emerging evidence using TRP channel knockout mice indicates that these channels have broad function in physiology. Here we review the recent progress on the physiology, pharmacology and pathophysiological function of mammalian TRP channels.
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Affiliation(s)
- Long-Jun Wu
- Howard Hughes Medical Institute, Department of Cardiology, Children's Hospital Boston, 320 Longwood Avenue, Boston, MA 02115, USA
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417
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Jiang LH, Yang W, Zou J, Beech DJ. TRPM2 channel properties, functions and therapeutic potentials. Expert Opin Ther Targets 2010; 14:973-88. [PMID: 20670202 DOI: 10.1517/14728222.2010.510135] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
IMPORTANCE OF THE FIELD Oxidative stress, through production of reactive oxygen species, triggers disturbance in intracellular calcium [Ca(2+)](i) homeostasis, which has been identified as an important causative factor in the pathogenesis of numerous inflammatory, cardiovascular and neurodegenerative diseases. AREAS COVERED IN THIS REVIEW Transient receptor potential melastatin 2 (TRPM2) protein forms a Ca(2+)-permeable cationic channel that is activated in response to oxidative stress and therefore acts as a cellular redox sensor. Research over the years has substantially advanced the knowledge of expression and functional properties of the TRPM2 channel, and particularly has accumulated compelling evidence for an important role for TRPM2 channel-mediated extracellular Ca(2+) influx in several physiological and pathophysiological functions exemplified by insulin release from pancreatic beta-cells, production of pro-inflammatory cytokines from immune cells, increased endothelial permeability, microglia activation and cell death. These findings suggest therapeutic potential of the TRPM2 channel as a drug target for combating oxidative-stress-related diseases. WHAT THE READER WILL GAIN The current state of knowledge with respect to the TRPM2 channel properties and the roles in oxidant stress signalling and functions. TAKE HOME MESSAGE TRPM2 may be a novel therapeutic target for oxidative stress-related diseases.
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Affiliation(s)
- Lin-Hua Jiang
- University of Leeds, Institute of Membrane and Systems Biology, England, UK.
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418
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Endogenous lipid-derived ligands for sensory TRP ion channels and their pain modulation. Arch Pharm Res 2010; 33:1509-20. [DOI: 10.1007/s12272-010-1004-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 08/25/2010] [Accepted: 08/27/2010] [Indexed: 10/18/2022]
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419
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Patel S, Marchant JS, Brailoiu E. Two-pore channels: Regulation by NAADP and customized roles in triggering calcium signals. Cell Calcium 2010; 47:480-90. [PMID: 20621760 DOI: 10.1016/j.ceca.2010.05.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 04/30/2010] [Accepted: 05/03/2010] [Indexed: 01/11/2023]
Abstract
NAADP is a potent regulator of cytosolic calcium levels. Much evidence suggests that NAADP activates a novel channel located on an acidic (lysosomal-like) calcium store, the mobilisation of which results in further calcium release from the endoplasmic reticulum. Here, we discuss the recent identification of a family of poorly characterized ion channels (the two-pore channels) as endo-lysosomal NAADP receptors. The generation of calcium signals by these channels is likened to those evoked by depolarisation during excitation-contraction coupling in muscle. We discuss the idea that two-pore channels can mediate a trigger release of calcium which is then amplified by calcium-induced calcium release from the endoplasmic reticulum. This is similar to the activation of voltage-sensitive calcium channels and subsequent mobilisation of sarcoplasmic reticulum calcium stores in cardiac tissue. We suggest that two-pore channels may physically interact with ryanodine receptors to account for more direct release of calcium from the endoplasmic reticulum in analogy with the conformational coupling of voltage-sensitive calcium channels and ryanodine receptors in skeletal muscle. Interaction of two-pore channels with other calcium release channels likely occurs between stores "trans-chatter" and possibly within the same store "cis-chatter". We also speculate that trafficking of two-pore channels through the endo-lysosomal system facilitates interactions with calcium entry channels. Strategic placing of two-pore channels thus provides a versatile means of generating spatiotemporally complex cellular calcium signals.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, UK.
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420
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Li GY, Fan B, Zheng YC. Calcium overload is a critical step in programmed necrosis of ARPE-19 cells induced by high-concentration H₂O₂. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 2010; 23:371-377. [PMID: 21112485 DOI: 10.1016/s0895-3988(10)60078-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 08/20/2010] [Indexed: 05/30/2023]
Abstract
OBJECTIVE Oxidative stress plays an important role in retinal pigmental epithelium (RPE) death during aging and the development of age-related macular degeneration. Although early reports indicate that reactive oxygen species (ROS) including H₂O₂ can trigger apoptosis at lower concentrations and necrosis at higher concentrations, the exact molecular mechanism of RPE death is still unclear. The purpose of this study was to investigate the molecular pathways involved in RPE death induced by exogenous ROS, especially at higher concentrations. METHODS Cultured ARPE-19 cells were treated with H₂O₂ at different concentrations and cell viability was measured with the MTT assay. Cell death was morphologically studied by microscopy using APOPercentage assay and PI staining. Furthermore, the impact of oxidative stress on ARPE-19 cells was assessed by HO-1 and PARP-1 Western blotting and by the protection of antioxidant EGCG. Calcium influx was determined using the fura-2 calcium indicator and the role of intracellular calcium overload in ARPE-19 cell death was evaluated following cobalt treatment to block calcium effects. RESULTS H₂O₂ reduced the viability of ARPE-19 cells in a concentration-dependent manner, which was presented as a typical s-shaped curve. Cell death caused by high concentrations of H₂O₂ was confirmed to be programmed necrosis. Morphologically, dying ARPE-19 cells were extremely swollen and lost the integrity of their plasma membrane, positively detected with APOPercentage assay and PI staining. 24-hour treatment with 500 μmol/L H₂O₂ induced remarkable up-regulation of HO-1 and PARP-1 in ARPE-19 cells. Moreover, antioxidant treatment using EGCG effectively protected cells from H₂O₂-induced injury, increasing cell viability from 14.17%±2.31% to 85.77%±4.58%. After H₂O₂ treatment, intracellular calcium levels were highly elevated with a maximum concentration of 1200 nM. Significantly, the calcium channel inhibitor cobalt was able to blunt this calcium influx and blocked the necrotic pathway, rescuing the ARPE-19 cell from H₂O₂-induced death. CONCLUSIONS At high concentrations, H₂O₂ induces ARPE-19 cell death through a regulated necrotic pathway with calcium overload as a critical step in the cell death program.
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Affiliation(s)
- Guang-Yu Li
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun 130041, Jilin, China.
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421
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Simon F, Leiva-Salcedo E, Armisén R, Riveros A, Cerda O, Varela D, Eguiguren AL, Olivero P, Stutzin A. Hydrogen peroxide removes TRPM4 current desensitization conferring increased vulnerability to necrotic cell death. J Biol Chem 2010; 285:37150-8. [PMID: 20884614 DOI: 10.1074/jbc.m110.155390] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Necrosis is associated with an increase in plasma membrane permeability, cell swelling, and loss of membrane integrity with subsequent release of cytoplasmic constituents. Severe redox imbalance by overproduction of reactive oxygen species is one of the main causes of necrosis. Here we demonstrate that H(2)O(2) induces a sustained activity of TRPM4, a Ca(2+)-activated, Ca(2+)-impermeant nonselective cation channel resulting in an increased vulnerability to cell death. In HEK 293 cells overexpressing TRPM4, H(2)O(2) was found to eliminate in a dose-dependent manner TRPM4 desensitization. Site-directed mutagenesis experiments revealed that the Cys(1093) residue is crucial for the H(2)O(2)-mediated loss of desensitization. In HeLa cells, which endogenously express TRPM4, H(2)O(2) elicited necrosis as well as apoptosis. H(2)O(2)-mediated necrosis but not apoptosis was abolished by replacement of external Na(+) ions with sucrose or the non-permeant cation N-methyl-d-glucamine and by knocking down TRPM4 with a shRNA directed against TRPM4. Conversely, transient overexpression of TRPM4 in HeLa cells in which TRPM4 was previously silenced re-established vulnerability to H(2)O(2)-induced necrotic cell death. In addition, HeLa cells exposed to H(2)O(2) displayed an irreversible loss of membrane potential, which was prevented by TRPM4 knockdown.
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Affiliation(s)
- Felipe Simon
- Centro de Estudios Moleculares de la Célula and Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Av Independencia 1027, Independencia 838-0543, Santiago, Chile
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422
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Earley S. Vanilloid and melastatin transient receptor potential channels in vascular smooth muscle. Microcirculation 2010; 17:237-49. [PMID: 20536737 DOI: 10.1111/j.1549-8719.2010.00026.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The mammalian transient receptor potential (TRP) superfamily consists of six subfamilies that are defined by structural homology: TRPC (conventional or canonical), TRPV (vanilloid), TRPM (melastatin), TRPA (ankyrin), TRPP (polycystin), and TRPML (mucoliptin). This review focuses on channels belonging to the vanilloid (V) and melastatin (M) TRP subfamilies. The TRPV subfamily consists of six members (TRPV1-6) and the TRPM subfamily has eight (TRPM1-8). The basic biophysical properties of these channels are briefly described. All of these channels except TRPV5, TRPV6, and TRPM1 are reportedly present in arterial smooth muscle from various segments of the vasculature. Studies demonstrating involvement of TRPV1, TRPV2, TRPV4, TRPM4, TRPM7, and TRPM8 in regulation of arterial smooth muscle function are reviewed. The functions of TRPV3, TRPM2, TRPM3, and TRPM6 channels in arterial myocytes have not been reported.
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Affiliation(s)
- Scott Earley
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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423
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Yamamoto S, Takahashi N, Mori Y. Chemical physiology of oxidative stress-activated TRPM2 and TRPC5 channels. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:18-27. [DOI: 10.1016/j.pbiomolbio.2010.05.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 04/05/2010] [Accepted: 05/19/2010] [Indexed: 12/21/2022]
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424
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Jambunathan N, Penaganti A, Tang Y, Mahalingam R. Modulation of redox homeostasis under suboptimal conditions by Arabidopsis nudix hydrolase 7. BMC PLANT BIOLOGY 2010; 10:173. [PMID: 20704736 PMCID: PMC3095304 DOI: 10.1186/1471-2229-10-173] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Accepted: 08/12/2010] [Indexed: 05/06/2023]
Abstract
BACKGROUND Nudix hydrolases play a key role in maintaining cellular homeostasis by hydrolyzing various nuceloside diphosphate derivatives and capped mRNAs. Several independent studies have demonstrated that Arabidopsis nudix hydrolase 7 (AtNUDT7) hydrolyzes NADH and ADP-ribose. Loss of function Atnudt7-1 mutant plants (SALK_046441) exhibit stunted growth, higher levels of reactive oxygen species, enhanced resistance to pathogens. However, using the same T-DNA line, two other groups reported that mutant plants do not exhibit any visible phenotypes. In this study we analyze plausible factors that account for differences in the observed phenotypes in Atnudt7. Secondly, we evaluate the biochemical and molecular consequences of increased NADH levels due to loss of function of AtNUDT7 in Arabidopsis. RESULTS We identified a novel conditional phenotype of Atnudt7-1 knockout plants that was contingent upon nutrient composition of potting mix. In nutrient-rich Metro-Mix, there were no phenotypic differences between mutant and wild-type (WT) plants. In the nutrient-poor mix (12 parts vermiculite: 3 parts Redi-earth and 1 part sand), mutant plants showed the characteristic stunted phenotype. Compared with WT plants, levels of glutathione, NAD+, NADH, and in turn NADH:NAD+ ratio were higher in Atnudt7-1 plants growing in 12:3:1 potting mix. Infiltrating NADH and ADP-ribose into WT leaves was sufficient to induce AtNUDT7 protein. Constitutive over-expression of AtNudt7 did not alter NADH levels or resistance to pathogens. Transcriptome analysis identified nearly 700 genes differentially expressed in the Atnudt7-1 mutant compared to WT plants grown in 12:3:1 potting mix. In the Atnudt7-1 mutant, genes associated with defense response, proteolytic activities, and systemic acquired resistance were upregulated, while gene ontologies for transcription and phytohormone signaling were downregulated. CONCLUSIONS Based on these observations, we conclude that the differences observed in growth phenotypes of the Atnudt7-1 knockout mutants can be due to differences in the nutrient composition of potting mix. Our data suggests AtNUDT7 plays an important role in maintaining redox homeostasis, particularly for maintaining NADH:NAD+ balance for normal growth and development. During stress conditions, rapid induction of AtNUDT7 is important for regulating the activation of stress/defense signaling and cell death pathways.
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Affiliation(s)
- Niranjani Jambunathan
- 246 Noble Research Center, Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Anuradha Penaganti
- 246 Noble Research Center, Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Yuhong Tang
- The Samuel Roberts Noble Foundation Inc., Plant Biology Division, Ardmore, Oklahoma, USA
| | - Ramamurthy Mahalingam
- 246 Noble Research Center, Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, USA
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425
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Tong L, Denu JM. Function and metabolism of sirtuin metabolite O-acetyl-ADP-ribose. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1804:1617-25. [PMID: 20176146 PMCID: PMC3310390 DOI: 10.1016/j.bbapap.2010.02.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 02/04/2010] [Accepted: 02/07/2010] [Indexed: 10/19/2022]
Abstract
Sirtuins catalyze the NAD(+)-dependent deacetylation of target proteins, which are regulated by this reversible lysine modification. During deacetylation, the glycosidic bond of the nicotinamide ribose is cleaved to yield nicotinamide and the ribose accepts the acetyl group from substrate to produce O-acetyl-ADP-ribose (OAADPr), which exists as an approximately 50:50 mixture of 2' and 3' isomers at neutral pH. Discovery of this metabolite has fueled the idea that OAADPr may play an important role in the biology associated with sirtuins, acting as a signaling molecule and/or an important substrate for downstream enzymatic processes. Evidence for OAADPr-metabolizing enzymes indicates that at least three distinct activities exist that could modulate the cellular levels of this NAD(+)-derived metabolite. In Saccharomyces cerevisiae, NUDIX hydrolase Ysa1 cleaves OAADPr to AMP and 2- and 3-O-acetylribose-5-phosphate, lowering the cellular levels of OAADPr. A buildup of OAADPr and ADPr has been linked to a metabolic shift that lowers endogenous reactive oxygen species and diverts glucose towards preventing oxidative damage. In vitro, the mammalian enzyme ARH3 hydrolyzes OAADPr to acetate and ADPr. A third nuclear-localized activity appears to utilize OAADPr to transfer the acetyl-group to another small molecule, whose identity remains unknown. Recent studies suggest that OAADPr may regulate gene silencing by facilitating the assembly and loading of the Sir2-4 silencing complex onto nucleosomes. In mammalian cells, the Trpm2 cation channel is gated by both OAADPr and ADP-ribose. Binding is mediated by the NUDIX homology (NudT9H) domain found within the intracellular portion of the channel. OAADPr is capable of binding the Macro domain of splice variants from histone protein MacroH2A, which is highly enriched at heterochromatic regions. With recently developed tools, the pace of new discoveries of OAADPr-dependent processes should facilitate new molecular insight into the diverse biological processes modulated by sirtuins.
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Affiliation(s)
- Lei Tong
- Department of Biomolecular Chemistry, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, 53706
| | - John M. Denu
- Department of Biomolecular Chemistry, University of Wisconsin, School of Medicine and Public Health, Madison, Wisconsin, 53706
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426
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Yang W, Zou J, Xia R, Vaal ML, Seymour VA, Luo J, Beech DJ, Jiang LH. State-dependent inhibition of TRPM2 channel by acidic pH. J Biol Chem 2010; 285:30411-8. [PMID: 20660597 PMCID: PMC2945533 DOI: 10.1074/jbc.m110.139774] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Transient receptor potential melastatin 2 (TRPM2) channel fulfills an important role in oxidative stress signaling in immune and other cells, to which local extracellular acidosis is known to occur under physiological or pathological conditions and impose significant effects on their functions. Here, we investigated whether the ADP-ribose-activated TRPM2 channel is a target for modulation by extracellular acidic pH by patch clamp recording of HEK293 cells expressing hTRPM2 channel. Induced whole cell or single channel currents were rapidly inhibited upon subsequent exposure to acidic pH. The inhibition in the steady state was complete, voltage-independent, and pH-independent in the range of pH 4.0–6.0. The inhibition was irreversible upon returning to pH 7.3, suggesting channel inactivation. In contrast, exposure of closed channels to acidic pH reduced the subsequent channel activation in a pH-dependent manner with an IC50 for H+ of 20 μm (pH 4.7) and rendered subsequent current inhibition largely reversible, indicating differential or state-dependent inhibition and inactivation. Alanine substitution of residues in the outer vestibule of the pore including Lys952 and Asp1002 significantly slowed down or reduced acidic pH-induced inhibition and prevented inactivation. The results suggest that acidic pH acts as a negative feedback mechanism where protons bind to the outer vestibule of the TRPM2 channel pore and inhibit the TRPM2 channels in a state-dependent manner.
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Affiliation(s)
- Wei Yang
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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427
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Tóth B, Csanády L. Identification of direct and indirect effectors of the transient receptor potential melastatin 2 (TRPM2) cation channel. J Biol Chem 2010; 285:30091-102. [PMID: 20650899 DOI: 10.1074/jbc.m109.066464] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transient receptor potential melastatin 2 (TRPM2) is a Ca(2+)-permeable cation channel involved in physiological and pathophysiological processes linked to oxidative stress. TRPM2 channels are co-activated by intracellular Ca(2+) and ADP-ribose (ADPR) but also modulated in intact cells by several additional factors. Superfusion of TRPM2-expressing cells with H(2)O(2) or intracellular dialysis of cyclic ADPR (cADPR) or nicotinic acid adenine dinucleotide phosphate (NAADP) activates, whereas dialysis of AMP inhibits, TRPM2 whole-cell currents. Additionally, H(2)O(2), cADPR, and NAADP enhance ADPR sensitivity of TRPM2 currents in intact cells. Because in whole-cell recordings the entire cellular machinery for nucleotide and Ca(2+) homeostasis is intact, modulators might affect TRPM2 activity either directly, by binding to TRPM2, or indirectly, by altering the local concentrations of the primary ligands ADPR and Ca(2+). To identify direct modulators of TRPM2, we have studied the effects of H(2)O(2), AMP, cADPR, NAADP, and nicotinic acid adenine dinucleotide in inside-out patches from Xenopus oocytes expressing human TRPM2, by directly exposing the cytosolic faces of the patches to these compounds. H(2)O(2) (1 mM) and enzymatically purified cADPR (10 μM) failed to activate, whereas AMP (200 μM) failed to inhibit TRPM2 currents. NAADP was a partial agonist (maximal efficacy, ∼50%), and nicotinic acid adenine dinucleotide was a full agonist, but both had very low affinities (K(0.5) = 104 and 35 μM). H(2)O(2), cADPR, and NAADP did not enhance activation by ADPR. Considering intracellular concentrations of these compounds, none of them are likely to directly affect the TRPM2 channel protein in a physiological context.
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Affiliation(s)
- Balázs Tóth
- Department of Medical Biochemistry, Semmelweis University, Budapest H-1094, Hungary
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428
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Kühn FJP, Witschas K, Kühn C, Lückhoff A. Contribution of the S5-pore-S6 domain to the gating characteristics of the cation channels TRPM2 and TRPM8. J Biol Chem 2010; 285:26806-26814. [PMID: 20587417 DOI: 10.1074/jbc.m110.109975] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The closely related cation channels TRPM2 and TRPM8 show completely different requirements for stimulation and are regulated by Ca(2+) in an opposite manner. TRPM8 is basically gated in a voltage-dependent process enhanced by cold temperatures and cooling compounds such as menthol and icilin. The putative S4 voltage sensor of TRPM8 is closely similar to that of TRPM2, which, however, is mostly devoid of voltage sensitivity. To gain insight into principal interactions of critical channel domains during the gating process, we created chimeras in which the entire S5-pore-S6 domains were reciprocally exchanged. The chimera M2-M8P (i.e. TRPM2 with the pore of TRPM8) responded to ADP-ribose and hydrogen peroxide and was regulated by extracellular and intracellular Ca(2+) as was wild-type TRPM2. Single-channel recordings revealed the characteristic pattern of TRPM2 with extremely long open times. Only at far-negative membrane potentials (-120 to -140 mV) did differences become apparent because currents were reduced by hyperpolarization in M2-M8P but not in TRPM2. The reciprocal chimera, M8-M2P, showed currents after stimulation with high concentrations of menthol and icilin, but these currents were only slightly larger than in controls. The transfer of the NUDT9 domain to the C terminus of TRPM8 produced a channel sensitive to cold, menthol, or icilin but insensitive to ADP-ribose or hydrogen peroxide. We conclude that the gating processes in TRPM2 and TRPM8 differ in their requirements for specific structures within the pore. Moreover, the regulation by extracellular and intracellular Ca(2+) and the single-channel properties in TRPM2 are not determined by the S5-pore-S6 region.
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Affiliation(s)
- Frank J P Kühn
- Institute of Physiology, Medical Faculty, RWTH Aachen University, D-52057 Aachen, Germany.
| | - Katja Witschas
- Institute of Physiology, Medical Faculty, RWTH Aachen University, D-52057 Aachen, Germany
| | - Cornelia Kühn
- Institute of Physiology, Medical Faculty, RWTH Aachen University, D-52057 Aachen, Germany
| | - Andreas Lückhoff
- Institute of Physiology, Medical Faculty, RWTH Aachen University, D-52057 Aachen, Germany
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429
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Cao G, Lee KP, van der Wijst J, de Graaf M, van der Kemp A, Bindels RJM, Hoenderop JGJ. Methionine sulfoxide reductase B1 (MsrB1) recovers TRPM6 channel activity during oxidative stress. J Biol Chem 2010; 285:26081-7. [PMID: 20584906 DOI: 10.1074/jbc.m110.103655] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mg(2+) is an essential ion for many cellular processes, including protein synthesis, nucleic acid stability, and numerous enzymatic reactions. Mg(2+) homeostasis in mammals depends on the equilibrium between intestinal absorption, renal excretion, and exchange with bone. The transient receptor potential melastatin type 6 (TRPM6) is an epithelial Mg(2+) channel, which is abundantly expressed in the luminal membrane of the renal and intestinal cells. It functions as the gatekeeper of transepithelial Mg(2+) transport. Remarkably, TRPM6 combines a Mg(2+)-permeable channel with an alpha-kinase domain. Here, by the Ras recruitment system, we identified methionine sulfoxide reductase B1 (MsrB1) as an interacting protein of the TRPM6 alpha-kinase domain. Importantly, MsrB1 and TRPM6 are both present in the renal Mg(2+)-transporting distal convoluted tubules. MsrB1 has no effect on TRPM6 channel activity in the normoxic conditions. However, hydrogen peroxide (H(2)O(2)) decreased TRPM6 channel activity. Co-expression of MsrB1 with TRPM6 attenuated the inhibitory effect of H(2)O(2) (TRPM6, 67 +/- 5% of control; TRPM6 + MsrB1, 81 +/- 5% of control). Cell surface biotinylation assays showed that H(2)O(2) treatment does not affect the expression of TRPM6 at the plasma membrane. Next, mutation of Met(1755) to Ala in TRPM6 reduced the inhibitory effect of H(2)O(2) on TRPM6 channel activity (TRPM6 M1755A: 84 +/- 10% of control), thereby mimicking the action of MsrB1. Thus, these data suggest that MsrB1 recovers TRPM6 channel activity by reducing the oxidation of Met(1755) and could, thereby, function as a modulator of TRPM6 during oxidative stress.
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Affiliation(s)
- Gang Cao
- Department of Physiology, Radboud University Nijmegen Medical Centre, HB Nijmegen, The Netherlands
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430
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Grupe M, Myers G, Penner R, Fleig A. Activation of store-operated I(CRAC) by hydrogen peroxide. Cell Calcium 2010; 48:1-9. [PMID: 20646759 DOI: 10.1016/j.ceca.2010.05.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 05/14/2010] [Accepted: 05/18/2010] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) play a role in both innate immunity as well as cellular injury. H2O2 induces changes in intracellular calcium ([Ca(2+)]i) in many cell types and this seems to be at least partially mediated by transient receptor potential melastatin 2 (TRPM2) in cells that express this channel. Here we show that low concentrations of H2O2 induce the activation of the Ca(2+)-release activated Ca(2+) current I(CRAC). This effect is not mediated by direct CRAC channel activation, since H2O2 does not activate heterologously expressed CRAC channels independently of stromal interaction molecule (STIM). Instead, I(CRAC) activation is partially mediated by store depletion through activation of inositol 1,4,5 trisphosphate receptors (IP3R), since pharmacological inhibition of IP3 receptors by heparin or molecular knock-out of all IP3 receptors in DT40 B cells strongly reduce H2O2-induced I(CRAC). The remainder of H2O2-induced I(CRAC) activation is likely mediated by IP3R-independent store-depletion. Our data suggest that H2O2 can activate Ca(2+) entry through TRPM2 as well as store-operated CRAC channels, thereby adding a new facet to ROS-induced Ca(2+) signaling.
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Affiliation(s)
- Morten Grupe
- Laboratory of Cell and Molecular Signaling, Center for Biomedical Research at The Queen's Medical Center and John A. Burns School of Medicine at the University of Hawaii, 1301 Punchbowl St., Honolulu, HI 96813, USA
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431
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Protective effect of N-acetylcysteine against carmustine-induced myelotoxicity in rats. Food Chem Toxicol 2010; 48:1576-80. [DOI: 10.1016/j.fct.2010.03.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 03/10/2010] [Accepted: 03/17/2010] [Indexed: 11/18/2022]
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432
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Graham S, Ding M, Ding Y, Sours-Brothers S, Luchowski R, Gryczynski Z, Yorio T, Ma H, Ma R. Canonical transient receptor potential 6 (TRPC6), a redox-regulated cation channel. J Biol Chem 2010; 285:23466-76. [PMID: 20501650 PMCID: PMC2906337 DOI: 10.1074/jbc.m109.093500] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
This study examined the effect of H2O2 on the TRPC6 channel and its underlying mechanisms using a TRPC6 heterologous expression system. In TRPC6-expressing HEK293T cells, H2O2 significantly stimulated Ca2+ entry in a dose-dependent manner. Electrophysiological experiments showed that H2O2 significantly increased TRPC6 channel open probability and whole-cell currents. H2O2 also evoked a robust inward current in A7r5 vascular smooth muscle cells, which was nearly abolished by knockdown of TRPC6 using a small interfering RNA. Catalase substantially attenuated arginine vasopressin (AVP)-induced Ca2+ entry in cells co-transfected with TRPC6 and AVP V1 receptor. N-Ethylmaleimide and thimerosal were able to simulate the H2O2 response. Dithiothreitol or glutathione-reduced ethyl ester significantly antagonized the response. Furthermore, both N-ethylmaleimide- and H2O2-induced TRPC6 activations were only observed in the cell-attached patches but not in the inside-out patches. Moreover, 1-oleoyl-2-acetyl-sn-glycerol effect on TRPC6 was significantly greater in the presence of H2O2. Biotinylation assays revealed a significant increase in cell surface TRPC6 in response to H2O2. Similarly, in cells transfected with TRPC6-EGFP, confocal microscopy showed a significant increase in fluorescence intensity in the region of the cell membrane and adjacent to the membrane. AVP also increased the fluorescence intensity on the surface of the cells co-transfected with TRPC6-EGFP and V1 receptor, and this response was inhibited by catalase. These data indicate that H2O2 activates TRPC6 channels via modification of thiol groups of intracellular proteins. This cysteine oxidation-dependent pathway not only stimulates the TRPC6 channel by itself but also sensitizes the channels to diacylglycerol and promotes TRPC6 trafficking to the cell surface.
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Affiliation(s)
- Sarabeth Graham
- Department of Integrative Physiology and Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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433
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Dadon D, Minke B. Cellular functions of transient receptor potential channels. Int J Biochem Cell Biol 2010; 42:1430-45. [PMID: 20399884 DOI: 10.1016/j.biocel.2010.04.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 04/08/2010] [Accepted: 04/08/2010] [Indexed: 11/26/2022]
Abstract
Transient Receptor Potential channels are polymodal cellular sensors involved in a wide variety of cellular processes, mainly by increasing cellular Ca(2+). In this review we focus on the roles of these channels in: (i) cell death (ii) proliferation and differentiation and (iii) transmitter release. Cell death: Ca(2+) influx participates in apoptotic and necrotic cell death. The Ca(2+) permeability and high sensitivity of part of these channels to oxidative/metabolic stress make them important participants in cell death. Several examples are given. Transient Receptor Potential Melastatin 2 is activated by H(2)O(2), inducing cell death through an increase in cellular Ca(2+) and activation of Poly ADP-Ribose Polymerase. Exposure of cultured cortical neurons to oxygen-glucose deprivation, in vitro, causes cell death via cation influx, mediated by Transient Receptor Potential Melastatin 7. Metabolic stress constitutively activates the Ca(2+) permeable Transient Receptor Potential channels of Drosophila photoreceptor in the dark, potentially leading to retinal degeneration. Similar sensitivity to metabolic stress characterizes several mammalian Transient Receptor Potential Canonical channels. Proliferation and differentiation: The rise in cytosolic Ca(2+) induces cell growth, differentiation and proliferation via activation of several transcription factors. Activating a variety of store operated and Transient Receptor Potential channels cause a rise in cytosolic Ca(2+), making these channels components involved in proliferation and differentiation. Transmitter release: Transient Receptor Potential Melastatin 7 channels reside in synaptic vesicles and regulate neurotransmitter release by a mechanism that is not entirely clear. All the above features of Transient Receptor Potential channels make them crucial components in important, sometimes conflicting, cellular processes that still need to be explored.
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Affiliation(s)
- Daniela Dadon
- Department of Medical Neurobiology, The Institute of Medical Research Israel-Canada and the Kühne Minerva Center, for Studies of Visual Transduction, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
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434
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Grahnert A, Grahnert A, Klein C, Schilling E, Wehrhahn J, Hauschildt S. Review: NAD +: a modulator of immune functions. Innate Immun 2010; 17:212-33. [PMID: 20388721 DOI: 10.1177/1753425910361989] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Latterly, nicotinamide adenine dinucleotide (NAD+) has emerged as a molecule with versatile functions and of enormous impact on the maintenance of cell integrity. Besides playing key roles in almost all major aspects of energy metabolism, there is mounting evidence that NAD+ and its degradation products affect various biological activities including calcium homeostasis, gene transcription, DNA repair, and intercellular communication. This review is aimed at giving a brief insight into the life cycle of NAD+ in the cell, referring to synthesis, action and degradation aspects. With respect to their immunological relevance, the importance and function of the major NAD+ metabolizing enzymes, namely CD38/CD157, ADP-ribosyltransferases (ARTs), poly-ADP-ribose-polymerases (PARPs), and sirtuins are summarized and roles of NAD+ and its main degradation product adenosine 5'-diphosphoribose (ADPR) in cell signaling are discussed. In addition, an outline of the variety of immunological processes depending on the activity of nicotinamide phosphoribosyltransferase (Nampt), the key enzyme of the salvage pathway of NAD+ synthesis, is presented. Taken together, an efficient supply of NAD+ seems to be a crucial need for a multitude of cell functions, underlining the yet only partly revealed potency of this small molecule to influence cell fate.
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Affiliation(s)
- Andreas Grahnert
- Department of Immunobiology, Institute of Biology, University of Leipzig, Talstrasse 33, Leipzig, Germany
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435
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Bogeski I, Kummerow C, Al-Ansary D, Schwarz EC, Koehler R, Kozai D, Takahashi N, Peinelt C, Griesemer D, Bozem M, Mori Y, Hoth M, Niemeyer BA. Differential redox regulation of ORAI ion channels: a mechanism to tune cellular calcium signaling. Sci Signal 2010; 3:ra24. [PMID: 20354224 DOI: 10.1126/scisignal.2000672] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Reactive oxygen species (ROS) are involved in many physiological and pathophysiological cellular processes. We used lymphocytes, which are exposed to highly oxidizing environments during inflammation, to study the influence of ROS on cellular function. Calcium ion (Ca(2+)) influx through Ca(2+) release-activated Ca(2+) (CRAC) channels composed of proteins of the ORAI family is essential for the activation, proliferation, and differentiation of T lymphocytes, but whether and how ROS affect ORAI channel function have been unclear. Here, we combined Ca(2+) imaging, patch-clamp recordings, and measurements of cell proliferation and cytokine secretion to determine the effects of hydrogen peroxide (H(2)O(2)) on ORAI channel activity and human T helper lymphocyte (T(H) cell) function. ORAI1, but not ORAI3, channels were inhibited by oxidation by H(2)O(2). The differential redox sensitivity of ORAI1 and ORAI3 channels depended mainly on an extracellularly located reactive cysteine, which is absent in ORAI3. T(H) cells became progressively less redox-sensitive after differentiation into effector cells, a shift that would allow them to proliferate, differentiate, and secrete cytokines in oxidizing environments. The decreased redox sensitivity of effector T(H) cells correlated with increased expression of Orai3 and increased abundance of several cytosolic antioxidants. Knockdown of ORAI3 with small-interfering RNA rendered effector T(H) cells more redox-sensitive. The differential expression of Orai isoforms between naïve and effector T(H) cells may tune cellular responses under oxidative stress.
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Affiliation(s)
- Ivan Bogeski
- Department of Biophysics, Saarland University, 66421 Homburg, Germany.
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436
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Cook NL, Vink R, Helps SC, Manavis J, van den Heuvel C. Transient receptor potential melastatin 2 expression is increased following experimental traumatic brain injury in rats. J Mol Neurosci 2010; 42:192-9. [PMID: 20309649 DOI: 10.1007/s12031-010-9347-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 02/24/2010] [Indexed: 11/30/2022]
Abstract
Traumatic brain injury (TBI) elicits a sequence of complex biochemical changes including oxidative stress, oedema, inflammation and excitotoxicity. These factors contribute to the high morbidity and mortality following TBI, although their underlying molecular mechanisms remain poorly understood. Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel, highly expressed in the brain and immune cells. Recent studies have implicated TRPM2 channels in processes involving oxidative stress, inflammation and cell death. However, no studies have investigated the role of TRPM2 in TBI pathophysiology. In the present study, we have characterised TRPM2 mRNA and protein expression following experimental TBI. Adult male Sprague Dawley rats were injured using the impact-acceleration model of diffuse TBI with survival times between 5 and 5 days. Real-time RT-PCR (including reference gene validation studies) and semi-quantitative immunohistochemistry were used to quantify TRPM2 mRNA and protein levels, respectively, following TBI. Significant increases in TRPM2 mRNA and protein expression were observed in the cerebral cortex and hippocampus of injured animals, suggesting that TRPM2 may contribute to TBI injury processes such as oxidative stress, inflammation and neuronal death. Further characterisation of how TRPM2 may contribute to TBI pathophysiology is warranted.
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Affiliation(s)
- Naomi L Cook
- Discipline of Anatomy and Pathology, The University of Adelaide, Adelaide, Australia
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437
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Hong CW, Kim TK, Ham HY, Nam JS, Kim YH, Zheng H, Pang B, Min TK, Jung JS, Lee SN, Cho HJ, Kim EJ, Hong IH, Kang TC, Lee J, Oh SB, Jung SJ, Kim SJ, Song DK. Lysophosphatidylcholine Increases Neutrophil Bactericidal Activity by Enhancement of Azurophil Granule-Phagosome Fusion via Glycine·GlyRα2/TRPM2/p38 MAPK Signaling. THE JOURNAL OF IMMUNOLOGY 2010; 184:4401-13. [DOI: 10.4049/jimmunol.0902814] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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438
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Lau A, Tymianski M. Glutamate receptors, neurotoxicity and neurodegeneration. Pflugers Arch 2010; 460:525-42. [PMID: 20229265 DOI: 10.1007/s00424-010-0809-1] [Citation(s) in RCA: 802] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 02/16/2010] [Accepted: 02/18/2010] [Indexed: 02/07/2023]
Abstract
Glutamate excitotoxicity is a hypothesis that states excessive glutamate causes neuronal dysfunction and degeneration. As glutamate is a major excitatory neurotransmitter in the central nervous system (CNS), the implications of glutamate excitotoxicity are many and far-reaching. Acute CNS insults such as ischaemia and traumatic brain injury have traditionally been the focus of excitotoxicity research. However, glutamate excitotoxicity has also been linked to chronic neurodegenerative disorders such as amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease and others. Despite the continued research into the mechanisms of excitotoxicity, there are currently no pharmacological interventions capable of providing significant neuroprotection in the clinical setting of brain ischaemia or injury. This review addresses the current state of excitotoxic research, focusing on the structure and physiology of glutamate receptors; molecular mechanisms underlying excitotoxic cell death pathways and their interactions with each other; the evidence for glutamate excitotoxicity in acute neurologic diseases; laboratory and clinical attempts at modulating excitotoxicity; and emerging targets for excitotoxicity research.
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Affiliation(s)
- Anthony Lau
- Division of Applied and Interventional Research, Toronto Western Research Institute, 399 Bathurst Street, Toronto, ON, Canada, M5T 2S8
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439
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Lee M, Cho T, Jantaratnotai N, Wang YT, McGeer E, McGeer PL. Depletion of GSH in glial cells induces neurotoxicity: relevance to aging and degenerative neurological diseases. FASEB J 2010; 24:2533-45. [PMID: 20228251 DOI: 10.1096/fj.09-149997] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Oxidative stress induced by inhibition of glutathione (GSH) biosynthesis with D,L-buthionine-S,R-sulfoximine (BSO) causes human microglia, human astrocytes, THP-1 cells, and U373 cells to secrete materials toxic to human neuroblastoma SH-SY5Y cells and stimulates them to release TNF-alpha, IL-6, and nitrite ions. The effect is correlated with activation of the inflammatory pathways P38 MAP- kinase, Jun-N-terminal kinase, and NF-kappaB. The effect is reduced by adding to the medium GSH or clotrimazole (CTM), an inhibitor of Ca(2+)-influx through TRPM2 channels. It is also produced by inhibiting TRPM2 protein expression in microglia and astrocytes through introduction of its small inhibitory RNA (siRNA). TRPM2 mRNA is expressed by glial cells but not by SH-SY5Y cells. BSO in the culture medium causes an almost 3-fold increase in [Ca(2+)](i) in microglia and astrocytes over a 24-h period, which is reduced to half by the addition of CTM. The data strongly suggest that inhibiting intracellular GSH synthesis induces a neuroinflammatory response in human microglia and astrocytes, which is linked to Ca(2+) influx through TRPM2 channels. It represents a new model for inducing neuroinflammation and suggests that increasing GSH levels in glial cells may confer neuroprotection in neurodegenerative diseases, such as Alzheimer disease, which have a prominent neuroinflammatory component.
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Affiliation(s)
- Moonhee Lee
- Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
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440
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Zholos A. Pharmacology of transient receptor potential melastatin channels in the vasculature. Br J Pharmacol 2010; 159:1559-71. [PMID: 20233227 DOI: 10.1111/j.1476-5381.2010.00649.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mammalian transient receptor potential melastatin (TRPM) non-selective cation channels, the largest TRP subfamily, are widely expressed in excitable and non-excitable cells where they perform diverse functions ranging from detection of cold, taste, osmolarity, redox state and pH to control of Mg(2+) homeostasis and cell proliferation or death. Recently, TRPM gene expression has been identified in vascular smooth muscles with dominance of the TRPM8 channel. There has been in parallel considerable progress in decoding the functional roles of several TRPMs in the vasculature. This research on native cells is aided by the knowledge of the activation mechanisms and pharmacological properties of heterologously expressed TRPM subtypes. This paper summarizes the present state of knowledge of vascular TRPM channels and outlines several anticipated directions of future research in this area.
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Affiliation(s)
- Alexander Zholos
- Centre for Vision and Vascular Science, Queen's University of Belfast, UK.
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441
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Starkus JG, Fleig A, Penner R. The calcium-permeable non-selective cation channel TRPM2 is modulated by cellular acidification. J Physiol 2010; 588:1227-40. [PMID: 20194125 DOI: 10.1113/jphysiol.2010.187476] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
TRPM2 is a calcium-permeable non-selective cation channel expressed in the plasma membrane and in lysosomes that is critically involved in aggravating reactive oxygen species (ROS)-induced inflammatory processes and has been implicated in cell death. TRPM2 is gated by ADP-ribose (ADPR) and modulated by physiological processes that produce peroxide, cyclic ADP-ribose (cADPR), nicotinamide adenine dinucleotide phosphate (NAADP) and Ca(2+). We investigated the role of extra- and intracellular acidification on heterologously expressed TRPM2 in HEK293 cells. Our results show that TRPM2 is inhibited by external acidification with an IC(50) of pH 6.5 and is completely suppressed by internal pH of 6. Current inhibition requires channel opening and is strongly voltage dependent, being most effective at negative potentials. In addition, increased cytosolic pH buffering capacity or elevated [Ca(2+)](i) reduces the rate of current inactivation elicited by extracellular acidification, and Na(+) and Ca(2+) influence the efficacy of proton-induced inactivation. Together, these results suggest that external protons permeate TRPM2 channels to gain access to an intracellular site that regulates channel activity. Consistent with this notion, single-channel measurements in HEK293 cells reveal that internal protons induce channel closure without affecting single-channel conductance, whereas external protons affect channel open probability as well as single-channel conductance of native TRPM2 in neutrophils. We conclude that protons compete with Na(+) and Ca(2+) for channel permeation and channel closure results from a competitive antagonism of protons at an intracellular Ca(2+) binding site.
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Affiliation(s)
- John G Starkus
- University of Hawaii, Pacific Biosciences Research Center, Queens Medical Center, University Tower, 814, 1356 Lusitania Street, Honolulu, HI 96813, USA.
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442
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Trebak M, Ginnan R, Singer HA, Jourd'heuil D. Interplay between calcium and reactive oxygen/nitrogen species: an essential paradigm for vascular smooth muscle signaling. Antioxid Redox Signal 2010; 12:657-74. [PMID: 19719386 PMCID: PMC2861541 DOI: 10.1089/ars.2009.2842] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Signaling cascades initiated or regulated by calcium (Ca(2+)), reactive oxygen (ROS), and nitrogen (RNS) species are essential to diverse physiological and pathological processes in vascular smooth muscle. Stimuli-induced changes in intracellular Ca(2+) regulate the activity of primary ROS and RNS, producing enzymes including NADPH oxidases (Nox) and nitric oxide synthases (NOS). At the same time, alteration in intracellular ROS and RNS production reciprocates through redox-based post-translational modifications altering Ca(2+) signaling networks. These may include Ca(2+) pumps such as sarcoplasmic endoplasmic reticulum Ca(2+)-ATPase (SERCA), voltage-gated channels, transient receptor potential canonical (TRPC), melastatin2 (TRPM2), and ankyrin1 (TRPA1) channels, store operated Ca(2+) channels such as Orai1/stromal interaction molecule 1 (STIM1), and Ca(2+) effectors such as Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). In this review, we summarize and highlight current experimental evidence supporting the idea that cross-talk between Ca(2+) and ROS/RNS may represent a well-integrated signaling network in vascular smooth muscle.
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Affiliation(s)
- Mohamed Trebak
- Center for Cardiovascular Sciences, Albany Medical College, New York, USA
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443
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KIYONAKA S, KATO K, NISHIDA M, MORI Y. Pharmacological Properties of Novel TRPC Channel Inhibitors. YAKUGAKU ZASSHI 2010; 130:303-11. [DOI: 10.1248/yakushi.130.303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Shigeki KIYONAKA
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University
| | - Kenta KATO
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University
| | - Motohiro NISHIDA
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Yasuo MORI
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University
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444
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Ion channels and the hallmarks of cancer. Trends Mol Med 2010; 16:107-21. [PMID: 20167536 DOI: 10.1016/j.molmed.2010.01.005] [Citation(s) in RCA: 307] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 01/19/2023]
Abstract
Plasma membrane (PM) ion channels contribute to virtually all basic cellular processes and are also involved in the malignant phenotype of cancer cells. Here, we review the role of ion channels in cancer in the context of their involvement in the defined hallmarks of cancer: 1) self-sufficiency in growth signals, 2) insensitivity to antigrowth signals, 3) evasion of programmed cell death (apoptosis), 4) limitless replicative potential, 5) sustained angiogenesis and 6) tissue invasion and metastasis. Recent studies have indicated that the contribution of specific ion channels to these hallmarks varies for different types of cancer. Therefore, to determine the importance of ion channels as targets for cancer diagnosis and treatment their expression, function and regulation must be assessed for each cancer.
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445
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Regulation of chemokine production via oxidative pathway in HeLa cells. Mediators Inflamm 2010; 2009:183760. [PMID: 20150959 PMCID: PMC2817504 DOI: 10.1155/2009/183760] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 11/03/2009] [Indexed: 11/30/2022] Open
Abstract
Inflammation is associated with disease progression and, by largely unknown mechanisms, has been said to drive oncogenesis. At inflamed sites, neutrophils deploy a potent antimicrobial arsenal that includes proteinases, antimicrobial peptides, and ROS. Reactive oxygen species (ROSs) induce chemokines. In the present study, the concentrations of IL-8 in culture supernatants of HeLa cells treated with ROS were determined by enzyme-linked immunosorbent assay. We used o-phenanthroline to deplete Fe2+ in order to investigate the mechanisms through which ROSs induce IL-8 secretion in our system.
The iron chelator o-phenanthroline effectively inhibited H2O2-induced ERK2 activation. Enzyme-linked immunosorbent assays showed that IL-8 protein secretion was elevated in ROS-treated HeLa cells. When Fe2+ was removed from these cells, IL-8 secretion was inhibited. Collectively, these results indicate that Fe2+-mediated Erk pathway activation is an important signal transduction pathway in ROS-induced IL-8 secretion in epithelial cells.
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446
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Wehrhahn J, Kraft R, Harteneck C, Hauschildt S. Transient receptor potential melastatin 2 is required for lipopolysaccharide-induced cytokine production in human monocytes. THE JOURNAL OF IMMUNOLOGY 2010; 184:2386-93. [PMID: 20107186 DOI: 10.4049/jimmunol.0902474] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Transient receptor potential melastatin 2 (TRPM2) is a Ca(2+)-permeable nonselective cation channel that is stimulated by oxidative stress and specifically activated by intracellular ADP-ribose. Because TRPM2 is highly expressed in immunocytes, a role of this channel in inflammation processes has been proposed. The aim of the current study was to determine the function of TRPM2 in LPS-induced cytokine production of human monocytes. Incubation of human primary monocytes with LPS resulted in an upregulation of TRPM2 mRNA, protein, and of ADP-ribose-induced membrane currents. By using short hairpin RNA to downregulate TRPM2 expression in THP-1 monocytes, we demonstrate that TRPM2 is required for the LPS-induced production of IL-6, IL-8, IL-10, and TNF-alpha. Application of LPS led to a time-dependent increase in intracellular Ca(2+) concentrations in THP-1 cells that was clearly reduced by downregulation of TRPM2. Omission of extracellular Ca(2+) strongly decreased TNF-alpha production in TRPM2-expressing cells. Thus, TRPM2-mediated Ca(2+) entry is a central mechanism for LPS-induced cytokine production in monocytic cells. The identification of TRPM2 as a major player in this LPS-dependent process makes it a promising tool in modulating monocyte functions.
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Affiliation(s)
- Janine Wehrhahn
- Department of Immunobiology, Institute of Biology II, University of Leipzig, 04277 Leipzig, Germany
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447
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Cook NL, Kleinig TJ, van den Heuvel C, Vink R. Reference genes for normalising gene expression data in collagenase-induced rat intracerebral haemorrhage. BMC Mol Biol 2010; 11:7. [PMID: 20089183 PMCID: PMC2823748 DOI: 10.1186/1471-2199-11-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 01/20/2010] [Indexed: 12/14/2022] Open
Abstract
Background The mechanisms of brain injury following intracerebral haemorrhage (ICH) are incompletely understood. Gene expression studies using quantitative real-time RT-PCR following ICH have increased our understanding of these mechanisms, however the inconsistent results observed may be related to inappropriate reference gene selection. Reference genes should be stably expressed across different experimental conditions, however, transcript levels of common reference genes have been shown to vary considerably. Reference gene panels have therefore been proposed to overcome this potential confounder. Results The present study evaluated the stability of seven candidate reference genes in the striatum and overlying cortex of collagenase-induced ICH in rodents at survival times of 5 and 24 hours. Transcript levels of the candidate reference genes were quantified and ranked in order of stability using geNorm. When our gene of interest, transient receptor potential melastatin 2 (TRPM2), was normalised against each reference gene individually, TRPM2 mRNA levels were highly variable. When normalised to the four most stable reference genes selected for accurate normalisation of data, we found no significant difference between ICH and vehicle rats. Conclusion The panel of reference genes identified in the present study will enable more accurate normalisation of gene expression data in the acute phase of experimental ICH.
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Affiliation(s)
- Naomi L Cook
- Discipline of Anatomy and Pathology, School of Medical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
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448
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Islam MS. Calcium signaling in the islets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:235-59. [PMID: 20217501 DOI: 10.1007/978-90-481-3271-3_11] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Easy access to rodent islets and insulinoma cells and the ease of measuring Ca(2+) by fluorescent indicators have resulted in an overflow of data that have clarified minute details of Ca(2+) signaling in the rodent islets. Our understanding of the mechanisms and the roles of Ca(2+) signaling in the human islets, under physiological conditions, has been hugely influenced by uncritical extrapolation of the rodent data obtained under suboptimal experimental conditions. More recently, electrophysiological and Ca(2+) studies have elucidated the ion channel repertoire relevant for Ca(2+) signaling in the human islets and have examined their relative importance. Many new channels belonging to the transient receptor potential (TRP) family are present in the beta-cells. Ryanodine receptors, nicotinic acid adenine dinucleotide phosphate channel, and Ca(2+)-induced Ca(2+) release add new dimension to the complexity of Ca(2+) signaling in the human beta-cells. A lot more needs to be learnt about the roles of these new channels and CICR, not because that will be easy but because that will be difficult. Much de-learning will also be needed. Human beta-cells do not have a resting state in the normal human body even under physiological fasting conditions. Their membrane potential under physiologically relevant resting conditions is approximately -50 mV. Biphasic insulin secretion is an experimental epiphenomenon unrelated to the physiological pulsatile insulin secretion into the portal vein in the human body. Human islets show a wide variety of electrical activities and patterns of [Ca(2+)](i) changes, whose roles in mediating pulsatile secretion of insulin into the portal vein remain questionable. Future studies will hopefully be directed toward a better understanding of Ca(2+) signaling in the human islets in the context of the pathogenesis and treatment of human diabetes.
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Affiliation(s)
- M Shahidul Islam
- Department of Clinical Sciences and Education, Södersjukhuset, Karolinska Institutet, Research Center, 118 83 Stockholm, Sweden.
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449
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Lev S, Minke B. Constitutive activity of TRP channels methods for measuring the activity and its outcome. Methods Enzymol 2010; 484:591-612. [PMID: 21036252 PMCID: PMC3104132 DOI: 10.1016/b978-0-12-381298-8.00029-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
TRP channels participate in many cellular processes including cell death. These channels mediate these effects mainly by changing the cellular concentration of Ca(2+), a prominent cellular second messenger. Measuring the current-voltage relationship and state of activation of TRP channels is of utmost importance for evaluating their contribution to a cellular process within a spatial and temporal context. The study of TRP channels and characterization of their mode of activation will benefit and progress our understanding of each channel's role in specific cellular mechanisms. Many TRP channels exhibit constitutive activity, which is mostly observed in cell-based expression systems. This constitutive activity can lead, in many cases, to cellular degeneration, which can be readily observed morphologically and by biochemical assays. This chapter describes in brief different modes of TRP channel activity and their current-voltage relationships. The chapter outlines methods for visualizing this activity and methods to correlate between TRP channel activity and cell death, and it illustrates mechanisms that prevent cell death in spite of constitutive activity. Finally, it describes methods for qualitatively and quantitatively measuring the accompanied cellular degeneration.
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450
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Novel role for the transient receptor potential channel TRPM2 in prostate cancer cell proliferation. Prostate Cancer Prostatic Dis 2009; 13:195-201. [PMID: 20029400 PMCID: PMC2871075 DOI: 10.1038/pcan.2009.55] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We have identified a novel function for a member of the transient receptor potential (TRP) protein super-family, TRPM2, in prostate cancer cell proliferation. TRPM2 encodes a non-selective cation-permeable ion channel. We found that selectively knocking down TRPM2 with the small interfering RNA technique inhibited the growth of prostate cancer cells but not of non-cancerous cells. The subcellular localization of this protein is also remarkably different between cancerous and non-cancerous cells. In BPH-1 (benign), TRPM2 protein is homogenously located near the plasma membrane and in the cytoplasm, whereas in the cancerous cells (PC-3 and DU-145), a significant amount of the TRPM2 protein is located in the nuclei in a clustered pattern. Furthermore, we have found that TRPM2 inhibited nuclear ADP-ribosylation in prostate cancer cells. However, TRPM2 knockdown-induced inhibition of proliferation is independent of the activity of poly(ADP-ribose) polymerases. We conclude that TRPM2 is essential for prostate cancer cell proliferation and may be a potential target for the selective treatment of prostate cancer.
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