501
|
Abstract
The TRP (Transient Receptor Potential) superfamily of cation channels is remarkable in that it displays greater diversity in activation mechanisms and selectivities than any other group of ion channels. The domain organizations of some TRP proteins are also unusual, as they consist of linked channel and enzyme domains. A unifying theme in this group is that TRP proteins play critical roles in sensory physiology, which include contributions to vision, taste, olfaction, hearing, touch, and thermo- and osmosensation. In addition, TRP channels enable individual cells to sense changes in their local environment. Many TRP channels are activated by a variety of different stimuli and function as signal integrators. The TRP superfamily is divided into seven subfamilies: the five group 1 TRPs (TRPC, TRPV, TRPM, TRPN, and TRPA) and two group 2 subfamilies (TRPP and TRPML). TRP channels are important for human health as mutations in at least four TRP channels underlie disease.
Collapse
|
502
|
Zhao L, Wang Y, Sun N, Liu X, Li L, Shi J. Electroacupuncture regulates TRPM7 expression through the trkA/PI3K pathway after cerebral ischemia-reperfusion in rats. Life Sci 2007; 81:1211-22. [PMID: 17904584 DOI: 10.1016/j.lfs.2007.08.034] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 08/23/2007] [Accepted: 08/27/2007] [Indexed: 10/22/2022]
Abstract
Recently, it was demonstrated that TRPM7 is an essential mediator of anoxia-induced neuronal death. Meanwhile, nerve growth factor (NGF) is known to have survival and neuroprotective effects by interacting with the high affinity neurotrophin receptor, tropomyosin-related kinase A (trkA). In the present study, we found that electroacupuncture (EA) treatment could up-regulate trkA expression after focal cerebral ischemia in rats. At the same time, EA therapy obviously decreased the high expression of TRPM7 induced by ischemia. Using K252a to inhibit trkA, we found that the EA-mediated down-regulation of TRPM7 was significantly suppressed in rats subjected to cerebral ischemia. TrkA can utilize two distinct signaling pathways: the phosphatidylinositol 3-kinase (PI3K) pathway and the extracellular signal-related kinase (ERK) pathway. We found that the effect of EA on TRPM7 was also inhibited by a PI3K inhibitor, while an ERK inhibitor had no effect. Taken together, our findings suggest that EA can reverse the ischemia-induced increase of TRPM7 levels through the trkA-PI3K pathway.
Collapse
Affiliation(s)
- Li Zhao
- Department of Neurobiology, Key Laboratory of Neurological Disease of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, PR China
| | | | | | | | | | | |
Collapse
|
503
|
Ge X, Li GJ, Wang SB, Zhu H, Zhu T, Wang X, Xia Y. AtNUDT7, a negative regulator of basal immunity in Arabidopsis, modulates two distinct defense response pathways and is involved in maintaining redox homeostasis. PLANT PHYSIOLOGY 2007; 145:204-15. [PMID: 17660350 PMCID: PMC1976571 DOI: 10.1104/pp.107.103374] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 07/19/2007] [Indexed: 05/16/2023]
Abstract
Plants have evolved complicated regulatory systems to control immune responses. Both positive and negative signaling pathways interplay to coordinate development of a resistance response with the appropriate amplitude and duration. AtNUDT7, a Nudix domain-containing protein in Arabidopsis (Arabidopsis thaliana) that hydrolyzes nucleotide derivatives, was found to be a negative regulator of the basal defense response, and its loss-of-function mutation results in enhanced resistance to infection by Pseudomonas syringae. The nudt7 mutation does not cause a strong constitutive disease resistance phenotype, but it leads to a heightened defense response, including accelerated activation of defense-related genes that can be triggered by pathogenic and nonpathogenic microorganisms. The nudt7 mutation enhances two distinct defense response pathways: one independent of and the other dependent on NPR1 and salicylic acid accumulation. In vitro enzymatic assays revealed that ADP-ribose and NADH are preferred substrates of NUDT7, and the hydrolysis activity of NUDT7 is essential for its biological function and is sensitive to inhibition by Ca(2+). Further analyses indicate that ADP-ribose is not likely the physiological substrate of NUDT7. However, the nudt7 mutation leads to perturbation of cellular redox homeostasis and a higher level of NADH in pathogen-challenged leaves. The study suggests that the alteration in cellular antioxidant status caused by the nudt7 mutation primes the cells for the amplified defense response and NUDT7 functions to modulate the defense response to prevent excessive stimulation.
Collapse
Affiliation(s)
- Xiaochun Ge
- Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | | | | | | | | | | | | |
Collapse
|
504
|
Abstract
Reactive oxygen species (ROS) are generated in response to a number of physiologic or pathologic conditions. In addition to ROS produced extrinsically, a cell may produce ROS as a result of normal metabolism and signaling processes. When sufficient quantities of ROS are present within the cell, this oxidative stress may have profound effects on the cell, including the induction of cell death. Various signaling pathways are initiated in response to oxidative stress, through which the cell's demise is assured. Many of these signaling pathways involve cholesterol-enriched domains of the cell membrane known as lipid rafts. These lipid rafts are platforms for initiation or transduction of the signal and may modulate protein activity through a direct change in local membrane structure or by allowing protein-protein interactions to occur with higher affinity/specificity or both. Among the examples discussed in this review are death-receptor signaling, induction of membrane-associated tyrosine kinase activation, and activation of transient receptor protein (TRP) channels. Special attention also is given to the RIP1/TRAF2 pathway, which involves the downstream activation of the stress-activated protein kinase JNK. The activation of the JNK pathway plays a key role in the induction of cellular death in response to ROS.
Collapse
Affiliation(s)
- Michael J Morgan
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
505
|
Naziroğlu M, Lückhoff A, Jüngling E. Antagonist effect of flufenamic acid on TRPM2 cation channels activated by hydrogen peroxide. Cell Biochem Funct 2007; 25:383-7. [PMID: 16933200 DOI: 10.1002/cbf.1310] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The melastatin-related transient receptor potential channel TRPM2 is a plasma membrane Ca(2+)-permeable cation channel that is activated by hydrogen peroxide (H(2)O(2)) as a consequence of oxidative stress although the channel activation by H(2)O(2) appears to represent a cell-specific process in cells with endogenous expression of TRPM2. Flufenamic acid (FA) is a non-steroidal anti-inflammatory compound. Whether H(2)O(2) activates or FA inhibits TRPM2 channels in Chinese hamster ovary (CHO) cell is currently unknown. Due to lack of known antogonists of this channel, we demonstrate in CHO cells that FA inhibits TRPM2 activated by extracellular H(2)O(2). CHO cells were transfected with cDNA coding for TRPM2. Cells were studied with the conventional whole-cell patch clamp technique. The intracellular solution used EDTA (10 mM) as chelator for Ca(2+) and heavy metal ions. H(2)O(2) (10 mM) and FA (0.1 mM) were applied extracellularly. Non-selective cation currents were consistently induced by H(2)O(2). The time cause of H(2)O(2) effects was characterized by a delay of 2-5 min and a slow current induction to reach a plateau. The H(2)O(2)- induced inward current was effectively inhibited by 0.1 mM FA applied extracellularly. In conclusion, we have demonstrated that FA is an effective antogonist of TRPM2 channels and H(2)O(2)activated currents in CHO cells. FA in CHO cells may be considered, at best, a starting point for the development of TRPM2 channel blockers.
Collapse
Affiliation(s)
- Mustafa Naziroğlu
- Institute of Physiology, Medical Faculty, RWTH Aachen, Pauwelsstrasse, Aachen, Germany.
| | | | | |
Collapse
|
506
|
Kühn FJP, Knop G, Lückhoff A. The transmembrane segment S6 determines cation versus anion selectivity of TRPM2 and TRPM8. J Biol Chem 2007; 282:27598-609. [PMID: 17604279 DOI: 10.1074/jbc.m702247200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TRPM2 and TRPM8, closely related members of the transient receptor potential (TRP) family, are cation channels activated by quite different mechanisms. Their transmembrane segments S5 and S6 are highly conserved. To identify common structures in S5 and S6 that govern interaction with the pore, we created a chimera in which the S5-pore-S6 region of TRPM8 was inserted into TRPM2, along with a lysine at each transition site. Currents through this chimera were induced by ADP-ribose (ADPR) in cooperation with Ca(2+). In contrast to wild-type TRPM2 channels, currents through the chimera were carried by Cl(-), as demonstrated in ion substitution experiments using the cation N-methyl-D-glucamine (NMDG) and the anion glutamate. Extracellular NMDG had no effects. The substitution of either intracellular or extracellular Cl(-) with glutamate shifted the reversal potential, decreased the current amplitude and induced a voltage-dependent block relieved by depolarization. The lysine in S6 was responsible for the anion selectivity; insertion of a lysine into corresponding sites within S6 of either TRPM2 or TRPM8 created anion channels that were activated by ADPR (TRPM2 I1045K) or by cold temperatures (TRPM8 V976K). The positive charge of the lysine was decisive for the glutamate block because the mutant TRPM2 I1045H displayed cation currents that were blocked at acidic but not alkaline intracellular pH values. We conclude that the distal part of S6 is crucial for the discrimination of charge. Because of the high homology of S6 in the whole TRP family, this new role of S6 may apply to further TRP channels.
Collapse
Affiliation(s)
- Frank J P Kühn
- Institute of Physiology, Medical Faculty, RWTH Aachen, D-52057 Aachen, Germany.
| | | | | |
Collapse
|
507
|
Fliegert R, Gasser A, Guse AH. Regulation of calcium signalling by adenine-based second messengers. Biochem Soc Trans 2007; 35:109-14. [PMID: 17233614 DOI: 10.1042/bst0350109] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
cADPR [cyclic ADPR (ADP-ribose)], NAADP (nicotinic acid-adenine dinucleotide phosphate) and ADPR belong to the family of adenine-containing second messengers. They are metabolically related and are all involved in the regulation of cellular Ca(2+) homoeostasis. Activation of specific plasma membrane receptors is connected to cADPR formation in many cell types and tissues. In contrast receptor-mediated formation of NAADP and ADPR has been shown only in a few selected cellular systems. The intracellular Ca(2+) channel triggered by cADPR is the RyR (ryanodine receptor); in the case of NAADP, both activation of RyR and a novel Ca(2+) channel have been proposed. In contrast, ADPR opens the non-specific cation channel TRPM2 [TRP (transient receptor potential) melastatin 2] that belongs to the TRP family of ion channels.
Collapse
Affiliation(s)
- R Fliegert
- The Calcium Signalling Group, Institute of Biochemistry and Molecular Biology I: Cellular Signal Transduction, Centre of Experimental Medicine, University Medical Centre Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | | | | |
Collapse
|
508
|
Kim D, Baraniuk JN. Sensing the air around us: the voltage-gated-like ion channel family. Curr Allergy Asthma Rep 2007; 7:85-92. [PMID: 17437677 DOI: 10.1007/s11882-007-0004-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ion channels are a complex set of proteins having many important physiologic and potentially pathologic roles. The flow of ions through these channels and the subsequent cellular depolarization can trigger complex mechanisms such as cardiac rhythm, hormone secretion, and numerous sensory experiences. The transient receptor potential (TRP) channels are an important means for multiple organ systems to interact with their environment. The various TRP channel subfamilies respond to voltage or to ligands such as G-protein coupled receptors. Their ability to sense temperature, pain, stretch, and osmolarity among others enables them to mediate responses such as smooth muscle contraction, cough, or sensation of pain.
Collapse
Affiliation(s)
- Dennis Kim
- Division of Rheumatology, Immunology and Allergy, Room B105, Lower Level Kober-Cogen Building, Georgetown University, 3800 Reservoir Road, NW, Washington, DC 20007-2197, USA
| | | |
Collapse
|
509
|
Naziroğlu M. New molecular mechanisms on the activation of TRPM2 channels by oxidative stress and ADP-ribose. Neurochem Res 2007; 32:1990-2001. [PMID: 17562166 DOI: 10.1007/s11064-007-9386-x] [Citation(s) in RCA: 241] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 05/11/2007] [Indexed: 01/01/2023]
Abstract
The Na(+) and Ca(2+)-permeable melastatin related transient receptor potential (TRPM2) cation 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, and binding to the channel's enzymatic Nudix domain. Since the mechanisms that lead to TRPM2 inhibiting in response to ADPR and H(2)O(2) are not understood, I reviewed the effects of various inhibitors such as flufenamic acid and PARP inhibitors on ADPR, NAD(+) and H(2)O(2)-induced TRPM2 currents. In our experimental study, TRPM2 cation channels in chinese hamster ovary transected cells were gated both by ADPR and NAD(+). In addition, H(2)O(2) seems to activate TRPM2 by changing to the hydroxyl radical in the intracellular space after passing the plasma membrane. Experimental studies with respect to patch-clamp and Ca(2+) imaging, inhibitor roles of antioxidants are also summarized in the review.
Collapse
Affiliation(s)
- Mustafa Naziroğlu
- Department of Biophysics, Medical (TIP) Faculty, Süleyman Demirel University, 32260 Cunur, Isparta, Turkey.
| |
Collapse
|
510
|
Lund FE. Signaling properties of CD38 in the mouse immune system: enzyme-dependent and -independent roles in immunity. Mol Med 2007. [PMID: 17380200 DOI: 10.2119/2006-00099.lund] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5th international CD38 meeting, held in Torino, Italy, spanned a range of topics from the role of CD38 as a signaling receptor in lymphocytic tumors to the importance of CD38-derived metabolites in NAD(+) metabolism, calcium signaling, and immune function. This meeting was particularly exciting as data were presented demonstrating that collaborative experiments between enzymologists, biochemists, cell biologists, immunologists, and clinicians have started to unravel the secrets of CD38 biology. It is now clear that all of the products of the CD38 enzyme reaction regulate calcium signal transduction in cell types as diverse as sea urchin oocytes and mammalian lymphocytes. It is also apparent that CD38 plays important immunomodulatory role(s), however there is still much debate on how CD38 mediates its immunoregulatory functions and whether the enzymatic products generated by CD38 are important for immunity. The data presented at this meeting have begun to resolve some of these controversies. First, CD38 regulates the function of leukocytes by enzyme-dependent and enzyme-independent mechanisms. Second, CD38 regulates inflammatory responses by modulating the activity of the responding leukocytes and by altering the activity of non-hematopoietic cells in the inflamed tissue. Finally, crosstalk between CD38 and other NAD(+) utilizing enzymes such as ART2, SIRT1, and PARP-1 impacts NAD(+) homeostasis, inflammation, and immunity. Thus, immunity is regulated by CD38 in multiple and unexpected ways and the new research challenge will be to determine whether we can exploit the complex biology of CD38 to therapeutically regulate the immune system.
Collapse
Affiliation(s)
- Frances E Lund
- Trudeau Institute, 154 Algonquin Ave., Saranac Lake, NY 12983, USA.
| |
Collapse
|
511
|
Bianchi BR, Moreland RB, Faltynek CR, Chen J. Application of Large-Scale Transiently Transfected Cells to Functional Assays of Ion Channels: Different Targets and Assay Formats. Assay Drug Dev Technol 2007; 5:417-24. [PMID: 17638541 DOI: 10.1089/adt.2006.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cell-based functional assays are increasingly being utilized for ion channels and other targets in drug discovery. However, development of functional assays is often hampered by problems related to stable expression of ion channels in host cell lines, such as variability in channel activity, cell line degeneration, toxicity associated with gene expression, and time and expense of maintaining the cells in culture. In a previous study, we showed that constitutive expression of the transient receptor potential ankyrin-1 (TRPA1) channel led to cellular toxicity and cell line degeneration. This problem could be circumvented by utilizing large-scale transiently transfected (LSTT) cells, which could be prepared in large quantity and kept frozen at -80 degrees C until needed. LSTT cells from a single preparation were successfully applied toward development of a Ca(2+) influx assay for TRPA1 and a high throughput screening of a >700,000 compound library. In the current study, we extended the application of LSTT cells to Ca(2+) influx assays for transient receptor potential vanilloid-1 (TRPV1), transient receptor potential melastatin-8, and transient receptor potential vanilloid-4 channels. In addition, we found that cryopreserved LSTT cells expressing TRPV1 exhibited the same pharmacology as a TRPV1 stable cell line in the Ca(2+) influx assay. Moreover, by using LSTT cells expressing TRPA1, we successfully developed a membrane potential assay, which gave comparable results to the Ca(2+) influx assay. Hence, the utilization of LSTT cells could reduce the need for stable cell lines, and enable development of functional assays in a more timely and economic fashion for different ion channels and different assay formats.
Collapse
Affiliation(s)
- Bruce R Bianchi
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064, USA
| | | | | | | |
Collapse
|
512
|
Abstract
Store-operated calcium (SOC) entry is the major route of calcium influx in non-excitable cells, especially immune cells. The best characterized store-operated current, I(CRAC), is carried by calcium release activated calcium (CRAC) channels. The existence of the phenomenon of store-operated calcium influx was proposed almost two decades ago. However, in spite of rigorous research by many laboratories, the identity of the key molecules participating in the process has remained a mystery. In all these years, multiple different approaches have been adopted by countless researchers to identify the molecular players in this fundamental process. Along the way, many crucial discoveries have been made, some of which have been summarized here. The last couple of years have seen significant breakthroughs in the field-identification of STIM1 as the store Ca(2+) sensor and CRACM1 (Orai1) as the pore-forming subunit of the CRAC channel. The field is now actively engaged in deciphering the gating mechanism of CRAC channels. We summarize here the latest progress in this direction.
Collapse
Affiliation(s)
- Monika Vig
- Laboratory of Allergy and Immunology, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston MA 02215, USA
| | - Jean-Pierre Kinet
- Laboratory of Allergy and Immunology, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston MA 02215, USA
- Correspondence should be addressed to: Jean-Pierre Kinet, 617 667 1324 (phone), 617 667 1323 (fax),
| |
Collapse
|
513
|
Abstract
✓Cerebral edema is caused by a variety of pathological conditions that affect the brain. It is associated with two separate pathophysiological processes with distinct molecular and physiological antecedents: those related to cytotoxic (cellular) edema of neurons and astrocytes, and those related to transcapillary flux of Na+and other ions, water, and serum macromolecules. In this review, the authors focus exclusively on the first of these two processes. Cytotoxic edema results from unchecked or uncompensated influx of cations, mainly Na+, through cation channels. The authors review the different cation channels that have been implicated in the formation of cytotoxic edema of astrocytes and neurons in different pathological states. A better understanding of these molecular mechanisms holds the promise of improved treatments of cerebral edema and of the secondary injury produced by this pathological process.
Collapse
Affiliation(s)
- Danny Liang
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA
| | | | | | | |
Collapse
|
514
|
Andersson DA, Nash M, Bevan S. Modulation of the cold-activated channel TRPM8 by lysophospholipids and polyunsaturated fatty acids. J Neurosci 2007; 27:3347-55. [PMID: 17376995 PMCID: PMC2726637 DOI: 10.1523/jneurosci.4846-06.2007] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We investigated the role of phospholipase A2 (PLA2) and the effects of PLA2 products (polyunsaturated fatty acids and lysophospholipids) on the cold-sensitive channel transient receptor potential (melastatin)-8 (TRPM8), heterologously expressed in Chinese hamster ovary cells. TRPM8 responses to cold and the agonist icilin were abolished by inhibitors of the calcium-independent (iPLA2) form of the enzyme, whereas responses to menthol were less sensitive to iPLA2 inhibition. Inhibition of PLA2 similarly abolished the cold responses of the majority of cold-sensitive dorsal root ganglion neurons. The products of PLA2 had opposing effects on TRPM8. Lysophospholipids (LPLs) (lysophosphatidylcholine, lysophosphatidylinositol, and lysophosphatidylserine) altered the thermal sensitivity of TRPM8, raising the temperature threshold toward normal body temperature. Polyunsaturated fatty acids (PUFAs), such as arachidonic acid, inhibited the activation of TRPM8 by cold, icilin, and menthol. The relative potencies of lysophospholipids and PUFAs are such that lysophosphatidylcholine is able to modulate TRPM8 in the presence of an equimolar concentration of arachidonic acid. Positive modulation by LPLs provides a potential physiological mechanism for sensitizing and activating TRPM8 in the absence of temperature variations.
Collapse
Affiliation(s)
- David A Andersson
- Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom.
| | | | | |
Collapse
|
515
|
Yamamoto S, Wajima T, Hara Y, Nishida M, Mori Y. Transient receptor potential channels in Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2007; 1772:958-67. [PMID: 17490865 DOI: 10.1016/j.bbadis.2007.03.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 03/22/2007] [Accepted: 03/22/2007] [Indexed: 01/20/2023]
Abstract
Cognitive impairment and emotional disturbances in Alzheimer's disease (AD) result from the degeneration of synapses and neuronal death in the limbic system and associated regions of the cerebral cortex. An alteration in the proteolytic processing of the amyloid precursor protein (APP) results in increased production and accumulation of amyloid beta-peptide (Abeta) in the brain. Abeta can render neurons vulnerable to excitotoxicity and apoptosis by disruption of cellular Ca(2+) homeostasis and neurotoxic factors including reactive oxygen species (ROS), nitric oxide (NO), and cytokines. Many lines of evidence have suggested that transient receptor potential (TRP) channels consisting of six main subfamilies termed the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and TRPA (ankyrin) are involved in Ca(2+) homeostasis disruption. Thus, emerging evidence of the pathophysiological role of TRP channels has yielded promising candidates for molecular entities mediating Ca(2+) homeostasis disruption in AD. In this review, we focus on the TRP channels in AD and highlight some TRP "suspects" for which a role in AD can be anticipated. An understanding of the involvement of TRP channels in AD may lead to the development of new target therapies.
Collapse
Affiliation(s)
- Shinichiro Yamamoto
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | | | | | | | | |
Collapse
|
516
|
Lund FE. Signaling properties of CD38 in the mouse immune system: enzyme-dependent and -independent roles in immunity. MOLECULAR MEDICINE (CAMBRIDGE, MASS.) 2007; 12:328-33. [PMID: 17380200 PMCID: PMC1829203 DOI: 10.2119/2006–00099.lund] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 12/07/2006] [Indexed: 11/06/2022]
Abstract
The 5th international CD38 meeting, held in Torino, Italy, spanned a range of topics from the role of CD38 as a signaling receptor in lymphocytic tumors to the importance of CD38-derived metabolites in NAD(+) metabolism, calcium signaling, and immune function. This meeting was particularly exciting as data were presented demonstrating that collaborative experiments between enzymologists, biochemists, cell biologists, immunologists, and clinicians have started to unravel the secrets of CD38 biology. It is now clear that all of the products of the CD38 enzyme reaction regulate calcium signal transduction in cell types as diverse as sea urchin oocytes and mammalian lymphocytes. It is also apparent that CD38 plays important immunomodulatory role(s), however there is still much debate on how CD38 mediates its immunoregulatory functions and whether the enzymatic products generated by CD38 are important for immunity. The data presented at this meeting have begun to resolve some of these controversies. First, CD38 regulates the function of leukocytes by enzyme-dependent and enzyme-independent mechanisms. Second, CD38 regulates inflammatory responses by modulating the activity of the responding leukocytes and by altering the activity of non-hematopoietic cells in the inflamed tissue. Finally, crosstalk between CD38 and other NAD(+) utilizing enzymes such as ART2, SIRT1, and PARP-1 impacts NAD(+) homeostasis, inflammation, and immunity. Thus, immunity is regulated by CD38 in multiple and unexpected ways and the new research challenge will be to determine whether we can exploit the complex biology of CD38 to therapeutically regulate the immune system.
Collapse
Affiliation(s)
- Frances E Lund
- Trudeau Institute, 154 Algonquin Ave., Saranac Lake, NY 12983, USA.
| |
Collapse
|
517
|
Cortright DN, Krause JE, Broom DC. TRP channels and pain. Biochim Biophys Acta Mol Basis Dis 2007; 1772:978-88. [PMID: 17467247 DOI: 10.1016/j.bbadis.2007.03.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 03/07/2007] [Accepted: 03/08/2007] [Indexed: 11/20/2022]
Abstract
Since the molecular identification of the capsaicin receptor, now known as TRPV1, transient receptor potential (TRP) channels have occupied an important place in the understanding of sensory nerve function in the context of pain. Several TRP channels exhibit sensitivity to substances previously known to cause pain or pain-like sensations; these include cinnamaldehyde, menthol, gingerol, and icillin. Many TRP channels also exhibit significant sensitivity to increases or decreases in temperature. Some TRP channels are sensitized in vitro by the activation of other receptors such that these channels may be activated by processes, such as inflammation that result in pain. TRP channels are suggested to be involved in processes as diverse as sensory neuron activation events, neurotransmitter release and action in the spinal cord, and release of inflammatory mediators. These functions strongly suggest that specific and selective inhibition of TRP channel activity will be of use in alleviating pain.
Collapse
|
518
|
Simard JM, Tarasov KV, Gerzanich V. Non-selective cation channels, transient receptor potential channels and ischemic stroke. Biochim Biophys Acta Mol Basis Dis 2007; 1772:947-57. [PMID: 17446049 PMCID: PMC1986778 DOI: 10.1016/j.bbadis.2007.03.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 03/13/2007] [Accepted: 03/13/2007] [Indexed: 02/02/2023]
Abstract
Several pathways to neural cell death are involved in ischemic stroke, and all require monovalent or divalent cation influx, implicating non-selective cation (NC) channels. NC channels are also likely to be involved in the dysfunction of vascular endothelial cells that leads to formation of edema following cerebral ischemia. Two newly described NC channels have emerged as potential participants in ischemic stroke, the acid sensing ion channel (ASIC), and the sulfonylurea receptor-1 (SUR1)-regulated NC(Ca-ATP) channel. Non-specific blockers of NC channels, including pinokalant (LOE 908 MS) and rimonabant (SR141716A), have beneficial effects in rodent models of ischemic stroke. Evidence is accumulating that NC channels formed by members of the transient receptor potential (TRP) family are also up-regulated in ischemic stroke and may play a direct role in calcium-mediated neuronal death. The nascent field of NC channels, including TRP channels, in ischemic stroke is poised to provide novel mechanistic insights and therapeutic strategies for this often devastating human condition.
Collapse
Affiliation(s)
- J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | | | | |
Collapse
|
519
|
Kwan HY, Huang Y, Yao X. TRP channels in endothelial function and dysfunction. Biochim Biophys Acta Mol Basis Dis 2007; 1772:907-14. [PMID: 17434294 DOI: 10.1016/j.bbadis.2007.02.013] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 02/27/2007] [Accepted: 02/27/2007] [Indexed: 11/29/2022]
Abstract
Endothelial cells produce various factors that regulate vascular tone, vascular permeability, angiogenesis, and inflammatory responses. The dysfunction of endothelial cells is believed to be the major culprit in various cardiovascular diseases, including hypertension, atherosclerosis, heart and renal failure, coronary syndrome, thrombosis, and diabetes. Endothelial cells express multiple transient receptor potential (TRP) channel isoforms, the activity of which serves to modulate cytosolic Ca(2+) levels ([Ca(2+)](i)) and regulate membrane potential, both of which affect various physiological processes. The malfunction and dysregulation of TRP channels is associated with endothelial dysfunction, which is reflected by decreased nitric oxide (NO) bioavailability, inappropriate regulation of vascular smooth muscle tonicity, endothelial barrier dysfunction, increased oxidative damage, impaired anti-thrombogenic properties, and perturbed angiogenic competence. Evidence suggests that dysregulation of TRPC4 and -C1 results in vascular endothelial barrier dysfunction; malfunction of TRPP1 and -P2 impairs endothelial NO synthase; the reduced expression or activity of TRPC4 and -V1 impairs agonist-induced vascular relaxation; the decreased activity of TRPV4 reduces flow-induced vascular responses; and the activity of TRPC3 and -C4 is associated with oxidative stress-induced endothelial damage. In this review, we present a comprehensive summary of the literature on the role of TRP channels in endothelial cells, with an emphasis on endothelial dysfunction.
Collapse
Affiliation(s)
- Hiu-Yee Kwan
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| | | | | |
Collapse
|
520
|
Porta S, Serra SA, Huch M, Valverde MA, Llorens F, Estivill X, Arbonés ML, Martí E. RCAN1 (DSCR1) increases neuronal susceptibility to oxidative stress: a potential pathogenic process in neurodegeneration. Hum Mol Genet 2007; 16:1039-50. [PMID: 17341486 DOI: 10.1093/hmg/ddm049] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Oxidative stress (OS) underlies neuronal dysfunction in many neurodegenerative disorders. Regulator of Calcineurin 1 (RCAN1 or DSCR1) is a dose-sensitive gene whose overexpression has been linked to Down syndrome (DS) and Alzheimer's disease (AD) neuropathology and to the response of cells to stress stimuli. Here, we show that RCAN1 mRNA and protein expression are sensitive to OS in primary neurons, and we evaluate the involvement of RCAN1 dosage in neuronal death induced by OS. We find that Rcan1(-/-) neurons display an increased resistance to damage by H(2)O(2), which can be reverted by RCAN1 overexpression or by exogenous inhibitors of calcineurin. Although increased intracellular Ca(2+) concentration is an important factor in OS-mediated cell death, our results show that Ca(2+) loading after exposure to H(2)O(2) was similar in Rcan1(+/+) and Rcan1(-/-) neurons. Our data further suggest that CaN and NFAT signaling protect against OS in both Rcan1(+/+) and Rcan1(-/-) neurons. To explain the observed differential vulnerability, we therefore propose a mechanism downstream of H(2)O(2)-mediated Ca(2+) entry, involving calcineurin-NFAT signaling. These findings highlight the importance of RCAN1 gene dosage in the modulation of cell survival and death pathways and suggest that changes in the amount of RCAN1 could represent an important mechanism for regulating susceptibility to neurodegeneration, especially in DS and AD.
Collapse
Affiliation(s)
- Sílvia Porta
- Genes and Disease Program, Center for Genomic Regulation (CRG-UPF), Biomedical Research Park Building, E-08003 Barcelona, Catalonia, Spain
| | | | | | | | | | | | | | | |
Collapse
|
521
|
Hermosura MC, Garruto RM. TRPM7 and TRPM2-Candidate susceptibility genes for Western Pacific ALS and PD? Biochim Biophys Acta Mol Basis Dis 2007; 1772:822-35. [PMID: 17395433 PMCID: PMC1994999 DOI: 10.1016/j.bbadis.2007.02.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 02/17/2007] [Accepted: 02/20/2007] [Indexed: 12/13/2022]
Abstract
Recent findings implicating TRPM7 and TRPM2 in oxidative stress-induced neuronal death thrust these channels into the spotlight as possible therapeutic targets for neurodegenerative diseases. In this review, we describe how the functional properties of TRPM7 and TRPM2 are interconnected with calcium (Ca(2+)) and magnesium (Mg(2+)) homeostasis, oxidative stress, mitochondrial dysfunction, and immune mechanisms, all principal suspects in neurodegeneration. We focus our discussion on Western Pacific Amyotrophic Lateral Sclerosis (ALS) and Parkinsonism Dementia (PD) because extensive studies conducted over the years strongly suggest that these diseases are ideal candidates for a gene-environment model of etiology. The unique mineral environment identified in connection with Western Pacific ALS and PD, low Mg(2+) and Ca(2+), yet high in transition metals, creates a condition that could affect the proper function of these two channels.
Collapse
Affiliation(s)
- Meredith C Hermosura
- Bekesy Laboratory of Neurobiology, Pacific Biosciences Research Center, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, HI 96822, USA.
| | | |
Collapse
|
522
|
Nilius B, Owsianik G, Voets T, Peters JA. Transient receptor potential cation channels in disease. Physiol Rev 2007; 87:165-217. [PMID: 17237345 DOI: 10.1152/physrev.00021.2006] [Citation(s) in RCA: 1035] [Impact Index Per Article: 60.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transient receptor potential (TRP) superfamily consists of a large number of cation channels that are mostly permeable to both monovalent and divalent cations. The 28 mammalian TRP channels can be subdivided into six main subfamilies: the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and the TRPA (ankyrin) groups. TRP channels are expressed in almost every tissue and cell type and play an important role in the regulation of various cell functions. Currently, significant scientific effort is being devoted to understanding the physiology of TRP channels and their relationship to human diseases. At this point, only a few channelopathies in which defects in TRP genes are the direct cause of cellular dysfunction have been identified. In addition, mapping of TRP genes to susceptible chromosome regions (e.g., translocations, breakpoint intervals, increased frequency of polymorphisms) has been considered suggestive of the involvement of these channels in hereditary diseases. Moreover, strong indications of the involvement of TRP channels in several diseases come from correlations between levels of channel expression and disease symptoms. Finally, TRP channels are involved in some systemic diseases due to their role as targets for irritants, inflammation products, and xenobiotic toxins. The analysis of transgenic models allows further extrapolations of TRP channel deficiency to human physiology and disease. In this review, we provide an overview of the impact of TRP channels on the pathogenesis of several diseases and identify several TRPs for which a causal pathogenic role might be anticipated.
Collapse
Affiliation(s)
- Bernd Nilius
- Department of Physiology, Campus Gasthuisberg, KULeuven, Leuven, Belgium.
| | | | | | | |
Collapse
|
523
|
Abstract
TRPM7 is a member of the melastatin-related subfamily of TRP channels and represents a protein that contains both an ion channel and a kinase domain. The protein is ubiquitously expressed and represents the only ion channel known that is essential for cellular viability. TRPM7 is a divalent cation-selective ion channel that is permeable to Ca2+ and Mg2+, but also conducts essential metals such as Zn2+, Mn2+, and Co2+, as well as nonphysiologic or toxic metals such as Ni2+, Cd2+, Ba2+, and Sr2+. The channel is constitutively open but strongly downregulated by intracellular levels of Mg2+ and MgATP and other Mg-nucleotides. Reducing the cellular levels of these regulators leads to activation of TRPM7-mediated currents that exhibit a characteristic nonlinear current-voltage relationship with pronounced outward rectification due to divalent influx at physiologically negative voltages and monovalent outward fluxes at positive voltages. TRPM7 channel activity is also actively regulated following receptor-mediated changes in cyclic AMP (cAMP) and protein kinase A activity. This regulation as well as that by Mg-nucleotides requires a functional endogenous kinase domain. The function of the kinase domain is not completely understood, but may involve autophosphorylation of TRPM7 as well as phosphorylation of other target proteins such as annexin and myosin IIA heavy chain. Based on these properties, TRPM7 is currently believed to represent a ubiquitous homeostatic mechanism that regulates Ca2+ and Mg2+ fluxes based on the metabolic state of the cell. Physiologically, the channel may serve as a regulated transport mechanism for these ions that could affect cell adhesion, cell growth and proliferation, and even cell death under pathological stress such as anoxia.
Collapse
Affiliation(s)
- R Penner
- Laboratory of Cell and Molecular Signaling, The Queen's Medical Center, 1301 Punchbowl Street-UHT 8, Honolulu, HI 96813, USA
| | | |
Collapse
|
524
|
Abstract
TRPM2 is a cation channel enabling influx of Na+ and Ca2+, leading to depolarization and increases in the cytosolic Ca2+ concentration ([Ca2+]i). It is widely expressed, e.g. in many neurons, blood cells and the endocrine pancreas. Channel gating is induced by ADP-ribose (ADPR) that binds to a Nudix box motif in the cytosolic C-terminus of the channel. Endogenous ADPR concentrations in leucocytes are sufficiently high to activate TRPM2 in the presence of an increased [Ca2+]i but probably not at resting [Ca2+]i. Another channel activator is oxidative stress, especially hydrogen peroxide (H2O2) that may act through ADPR after ADPR polymers have been formed by poly(ADP-ribose) polymerases (PARPs) and hydolysed by glycohydrolases. H2O2-stimulated TRPM2 channels essentially contribute to insulin secretion in pancreatic beta-cells and alloxan-induced diabetes mellitus. Inhibition of TRPM2 channels may be achieved by channel blockers such as flufenamic acid or the anti-fungal agents clotrimazole or econazole. Selective blockers of TRPM2 are not yet available; those would be valuable for a characterization of biological roles of TRPM2 in various tissues and as potential drugs directed against oxidative cell damage, reperfusion injury or leucocyte activation. Activation of TRPM2 may be prevented by anti-oxidants, PARP inhibitors and glycohydrolase inhibitors. In future, binding of ADPR to the Nudix box may be targeted. In light of the wide-spread expression and growing list of cellular functions of TRPM2, useful therapeutic applications are expected for future drugs that block TRPM2 channels or inhibit their activation.
Collapse
Affiliation(s)
- J Eisfeld
- Institut für Physiologie, Medizinische Fakultät, RWTH Aachen, Pauwelsstr. 30, 52057 Aachen, Germany
| | | |
Collapse
|
525
|
MacDonald JF, Jackson MF. Transient Receptor Potential Channels of the Melastatin Family and Ischemic Responses of Central Neurons. Stroke 2007; 38:665-9. [PMID: 17261711 DOI: 10.1161/01.str.0000251671.77351.e2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The excitotoxic theory of stroke, which implicated N-methyl-d-aspartate (NMDA) receptors as mediators of excessive Ca(2+) entry and neuronal death, generated a great deal of enthusiasm for the prospect of using NMDA receptor antagonists to prevent the associated brain injury. Unfortunately, these receptor antagonists failed to provide effective treatments for human stroke. In part, the failure is likely a consequence of having to administer these drugs within a very short therapeutic window after stroke and to the intolerable psychomimetic side effects associated with their use. However, new possibilities for therapeutic intervention are revealing themselves as our understanding of excitotoxicity evolves. We now recognize that ischemia and Ca(2+) toxicity in central neurons can be attributed to a variety of mechanisms recruited downstream of NMDA receptor activation. These include the activation of Ca(2+)-permeable transient receptor potential channels of the melastatin family. The more-delayed activation of these channels offers the tantalizing possibility that drugs targeting selected members of this family may possess a wider therapeutic window for preventing the debilitating consequences after stroke onset.
Collapse
Affiliation(s)
- John F MacDonald
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | | |
Collapse
|
526
|
Zhang W, Tong Q, Conrad K, Wozney J, Cheung JY, Miller BA. Regulation of TRP channel TRPM2 by the tyrosine phosphatase PTPL1. Am J Physiol Cell Physiol 2007; 292:C1746-58. [PMID: 17251321 DOI: 10.1152/ajpcell.00569.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TRPM2, a member of the transient receptor potential (TRP) superfamily, is a Ca(2+)-permeable channel, which mediates susceptibility to cell death following activation by oxidative stress, TNFalpha, or beta-amyloid peptide. We determined that TRPM2 is rapidly tyrosine phosphorylated after stimulation with H(2)O(2) or TNFalpha. Inhibition of tyrosine phosphorylation with the tyrosine kinase inhibitors genistein or PP2 significantly reduced the increase in [Ca(2+)](i) observed after H(2)O(2) or TNFalpha treatment in TRPM2-expressing cells, suggesting that phosphorylation is important in TRPM2 activation. Utilizing a TransSignal PDZ domain array blot to identify proteins which interact with TRPM2, we identified PTPL1 as a potential binding protein. PTPL1 is a widely expressed tyrosine phosphatase, which has a role in cell survival and tumorigenesis. Immunoprecipitation and glutathione-S-transferase pull-down assays confirmed that TRPM2 and PTPL1 interact. To examine the ability of PTPL1 to modulate phosphorylation or activation of TRPM2, PTPL1 was coexpressed with TRPM2 in human embryonic kidney-293T cells. This resulted in significantly reduced TRPM2 tyrosine phosphorylation, and inhibited the rise in [Ca(2+)](i) and the loss of cell viability, which follow H(2)O(2) or TNFalpha treatment. Consistent with these findings, reduction in endogenous PTPL1 expression with small interfering RNA resulted in increased TRPM2 tyrosine phosphorylation, a significantly greater rise in [Ca(2+)](i) following H(2)O(2) treatment, and enhanced susceptibility to H(2)O(2)-induced cell death. Endogenous TRPM2 and PTPL1 was associated in U937-ecoR cells, confirming the physiological relevance of this interaction. These data demonstrate that tyrosine phosphorylation of TRPM2 is important in its activation and function and that inhibition of TRPM2 tyrosine phosphorylation reduces Ca(2+) influx and protects cell viability. They also suggest that modulation of TRPM2 tyrosine phosphorylation is a mechanism through which PTPL1 may mediate resistance to cell death.
Collapse
Affiliation(s)
- Wenyi Zhang
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, PO Box 850, Hershey, PA 17033, USA
| | | | | | | | | | | |
Collapse
|
527
|
Carter CJ. Multiple genes and factors associated with bipolar disorder converge on growth factor and stress activated kinase pathways controlling translation initiation: implications for oligodendrocyte viability. Neurochem Int 2007; 50:461-90. [PMID: 17239488 DOI: 10.1016/j.neuint.2006.11.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 11/27/2006] [Indexed: 02/06/2023]
Abstract
Famine and viral infection, as well as interferon therapy have been reported to increase the risk of developing bipolar disorder. In addition, almost 100 polymorphic genes have been associated with this disease. Several form most of the components of a phosphatidyl-inositol signalling/AKT1 survival pathway (PIK3C3, PIP5K2A, PLCG1, SYNJ1, IMPA2, AKT1, GSK3B, TCF4) which is activated by growth factors (BDNF, NRG1) and also by NMDA receptors (GRIN1, GRIN2A, GRIN2B). Various other protein products of genes associated with bipolar disorder either bind to or are affected by phosphatidyl-inositol phosphate products of this pathway (ADBRK2, HIP1R, KCNQ2, RGS4, WFS1), are associated with its constituent elements (BCR, DUSP6, FAT, GNAZ) or are downstream targets of this signalling cascade (DPYSL2, DRD3, GAD1, G6PD, GCH1, KCNQ2, NOS3, SLC6A3, SLC6A4, SST, TH, TIMELESS). A further pathway relates to endoplasmic reticulum-stress (HSPA5, XBP1), caused by problems in protein glycosylation (ALG9), growth factor receptor sorting (PIK3C3, HIP1R, SYBL1), or aberrant calcium homoeostasis (WFS1). Key processes relating to these pathways appear to be under circadian control (ARNTL, CLOCK, PER3, TIMELESS). DISC1 can also be linked to many of these pathways. The growth factor pathway promotes protein synthesis, while the endoplasmic reticulum stress pathway, and other stress pathways activated by viruses and cytokines (IL1B, TNF, Interferons), oxidative stress or starvation, all factors associated with bipolar disorder risk, shuts down protein synthesis via control of the EIF2 alpha and beta translation initiation complex. For unknown reasons, oligodendrocytes appear to be particularly prone to defects in the translation initiation complex (EIF2B) and the convergence of these environmental and genomic signalling pathways on this area might well explain their vulnerability in bipolar disorder.
Collapse
|
528
|
Abstract
TRPC (canonical transient receptor potential) channels are the closest mammalian homologs of Drosophila TRP and TRP-like channels. TRPCs are rather nonselective Ca2+ permeable cation channels and affect cell functions through their ability to mediate Ca2+ entry into cells and their action to collapse the plasma membrane potentials. In neurons the latter function leads to action potentials. The mammalian genome codes for seven TRPCs of which TRPC2 is the largest with the most restricted pattern of expression and has several alternatively spliced variants. Expressed in model cells, TRPC2 mediates both receptor- and store depletion-triggered Ca2+ entry. TRPC2 is unique among TRPCs in that its complete gene has been lost from the Old World monkey and human genomes, in which its remnants constitute a pseudogene. Physiological roles for TRPC2 have been studied in mature sperm and the vomeronasal sensory system. In sperm, TRPC2 is activated by the sperm's interaction with the oocyte's zona pellucida, leading to entry of Ca2+ and activation of the acrosome reaction. In the vomeronasal sensory organ (VNO), TRPC2 was found to constitute the transduction channel activated through signaling cascade initiated by the interaction of pheromones with V1R and V2R G protein-coupled receptors on the dendrites of the sensory neurons. V1Rs and V2Rs, the latter working in conjunction with class I MHC molecules, activate G(i)- and G(o)-type G proteins which in turn trigger activation of TRPC2, initiating an axon potential that travels to the axonal terminals. The signal is then projected to the glomeruli of the auxiliary olfactory bulb from where it is carried first to the amygdala and then to higher cortical cognition centers. Immunocytochemistry and gene deletion studies have shown that (1) the V2R-G(o)-MHCIb-beta2m pathway mediates male aggressive behavior in response to pheromones; (2) the V1R-G(i2) pathway mediates mating partner recognition, and (3) these differences have an anatomical correlate in that these functional components are located in anatomically distinct compartments of the VNO. Interestingly, these anatomically segregated signaling pathways use a common transduction channel, TRPC2.
Collapse
Affiliation(s)
- E Yildirim
- Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | | |
Collapse
|
529
|
Abstract
Orchestrated ion fluctuations within pancreatic islets regulate hormone secretion and maybe essential to processes such as apoptosis. A diverse set of ion channels allows for islet cells to respond to a variety of signals and dynamically regulate hormone secretion and glucose homeostasis (reviewed by Houamed et al. 2004). This chapter focuses on transient receptor potential (TRP)-related channels found within the beta cells of the islet and reviews their roles in both insulin secretion and apoptosis.
Collapse
Affiliation(s)
- D A Jacobson
- Department of Medicine-Endocrinology Section, University of Chicago, 5841 S Maryland Ave, Chicago, IL, USA
| | | |
Collapse
|
530
|
Mei ZZ, Xia R, Beech DJ, Jiang LH. Intracellular coiled-coil domain engaged in subunit interaction and assembly of melastatin-related transient receptor potential channel 2. J Biol Chem 2006; 281:38748-56. [PMID: 17060318 PMCID: PMC1698503 DOI: 10.1074/jbc.m607591200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TRPM2 channels, activated by adenosine diphosphoribose and related molecules, are assembled as oligomers and most likely tetramers. However, the molecular determinants driving the subunit interaction and assembly of the TRPM2 channels are not well defined. Here we examined, using site-directed mutagenesis in conjunction with co-immunoprecipitation and patch clamp recording, the role of a coiled-coil domain in the intracellular C terminus of TRPM2 subunit in subunit interaction and channel assembly. Deletion of the coiled-coil domain resulted in severe disruption of the subunit interaction and substantial loss of the adenosine diphosphoribose-evoked channel currents. Individual or combined mutations to glutamine of the hydrophobic residues at positions a and d of the abcdef heptad repeat, key residues for protein-protein interaction, significantly reduced the subunit interaction and channel currents; the mutational effects on the subunit interaction and channel currents were clearly correlated. Furthermore, deletion of the coiled-coil domain in a pore mutant subunit abolished its dominant negative phenotypic functional suppression. These results provide strong evidence that the coiled-coil domain is critically engaged in the TRPM2 subunit interaction and such interaction is required for assembly of functional TRPM2 channel. The coiled-coil domain, which is highly conserved within the TRPM subfamily, may serve as a general structural element governing the assembly of TRPM channels.
Collapse
Affiliation(s)
- Zhu-Zhong Mei
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Rong Xia
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - David J Beech
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Lin-Hua Jiang
- From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| |
Collapse
|
531
|
Kraft R, Grimm C, Frenzel H, Harteneck C. Inhibition of TRPM2 cation channels by N-(p-amylcinnamoyl)anthranilic acid. Br J Pharmacol 2006; 148:264-73. [PMID: 16604090 PMCID: PMC1751561 DOI: 10.1038/sj.bjp.0706739] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. TRPM2 is a Ca2+ -permeable nonselective cation channel activated by intracellular ADP-ribose (ADPR) and by hydrogen peroxide (H2O2). We investigated the modulation of TRPM2 activity by N-(p-amylcinnamoyl)anthranilic acid (ACA). ACA has previously been reported to inhibit phospholipase A2 (PLA2). 2. Using patch-clamp and calcium-imaging techniques, we show that extracellular application of 20 microM ACA completely blocked ADPR-induced whole-cell currents and H2O2-induced Ca2+ signals (IC50 = 1.7 microM) in HEK293 cells transfected with human TRPM2. Two other PLA2 inhibitors, p-bromophenacyl bromide (BPB; 100 microM) and arachidonyl trifluoromethyl ketone (20 microM), had no significant effect on ADPR-stimulated TRPM2 activity. 3. Inhibition of TRPM2 whole-cell currents by ACA was voltage independent and accelerated at decreased pH. ACA was ineffective when applied intracellularly. The single-channel conductance was not changed during ACA treatment, suggesting a reduction of TRPM2 open probability by modulating channel gating. 4. ACA (20 microM) also blocked currents through human TRPM8 and TRPC6 expressed in HEK293 cells, while BPB (100 microM) was ineffective. TRPC6-mediated currents (IC50 = 2.3 microM) and TRPM8-induced Ca2+ signals (IC50 = 3.9 microM) were blocked in a concentration-dependent manner. 5. ADPR-induced currents in human U937 cells, endogeneously expressing TRPM2 protein, were fully suppressed by 20 microM ACA. 6. Our data indicate that ACA modulates the activity of different TRP channels independent of PLA2 inhibition. Owing to its high potency and efficacy ACA can serve, in combination with other blockers, as a useful tool for studying the unknown function of TRPM2 in native cells.
Collapse
Affiliation(s)
- Robert Kraft
- Institut für Pharmakologie, Charité Campus Benjamin Franklin, Thielallee 69-73, Berlin 14195, Germany
| | - Christian Grimm
- Institut für Pharmakologie, Charité Campus Benjamin Franklin, Thielallee 69-73, Berlin 14195, Germany
- Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany
| | - Henning Frenzel
- Institut für Pharmakologie, Charité Campus Benjamin Franklin, Thielallee 69-73, Berlin 14195, Germany
- Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany
| | - Christian Harteneck
- Institut für Pharmakologie, Charité Campus Benjamin Franklin, Thielallee 69-73, Berlin 14195, Germany
- Author for correspondence:
| |
Collapse
|
532
|
Massullo P, Sumoza-Toledo A, Bhagat H, Partida-Sánchez S. TRPM channels, calcium and redox sensors during innate immune responses. Semin Cell Dev Biol 2006; 17:654-66. [PMID: 17178241 DOI: 10.1016/j.semcdb.2006.11.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Melastatin-related TRPM ion channels have emerged as novel therapeutic targets due to their potential ability to modulate the function and fate of immune cells during inflammation, innate, and adaptive immunity. Four family members, TRPM1, TRPM2, TRPM4 and TRPM7 have a strong presence in the immune system. TRPM channels regulate ion-homeostasis by sensing cellular redox status and cytoplasmic calcium levels. TRPM2 for example, is highly expressed in phagocytes. This channel is activated by intracellular ADP-ribose upon exposure to oxidative stress and induces cell death. Here we will review the functional links between TRPM-mediated ion conductance, chemotaxis, apoptosis, and innate immunity.
Collapse
Affiliation(s)
- Pam Massullo
- Columbus Children's Research Institute, Center for Microbial Pathogenesis, The Ohio State University, Columbus, OH 43205, USA
| | | | | | | |
Collapse
|
533
|
Nishida M, Hara Y, Yoshida T, Inoue R, Mori Y. TRP channels: molecular diversity and physiological function. Microcirculation 2006; 13:535-50. [PMID: 16990213 DOI: 10.1080/10739680600885111] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Calcium ions (Ca(2+)) are particularly important in cellular homeostasis and activity. To elicit physiologically relevant timing and spatial patterns of Ca(2+) signaling, ion channels in the surface of each cell precisely control Ca(2+) influx across the plasma membrane. A group of surface membrane ion channels called receptor-activated cation/Ca(2+) channels (RACCs) are activated by diverse cellular stimuli from the surrounding extracellular environment via receptors and other pathways such as heat, osmotic pressure, and mechanical and oxidative stress. An important clue to understanding the molecular mechanisms underlying the functional diversity of RACCs was first attained by molecular identification of the transient receptor potential (trp) protein (TRP), which mediates light-induced depolarization in Drosophila photoreceptor cells, and its homologues from various biological species. Recent studies have revealed that respective TRP channels are indeed activated by characteristic cellular stimuli. Furthermore, the involvement of TRP channels has been demonstrated in the signaling pathways essential for tissue-specific functions as well as ubiquitous biological responses, such as cell proliferation, differentiation, and death. These findings encourage the usage of TRP channels and their signalplexes as powerful tools for developing novel pharmaceutical targets.
Collapse
Affiliation(s)
- Motohiro Nishida
- Department of Pharmacology & Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | | | | | | | | |
Collapse
|
534
|
Carter RN, Tolhurst G, Walmsley G, Vizuete-Forster M, Miller N, Mahaut-Smith MP. Molecular and electrophysiological characterization of transient receptor potential ion channels in the primary murine megakaryocyte. J Physiol 2006; 576:151-62. [PMID: 16857711 PMCID: PMC1995624 DOI: 10.1113/jphysiol.2006.113886] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 07/14/2006] [Indexed: 11/08/2022] Open
Abstract
The molecular identity of platelet Ca(2+) entry pathways is controversial. Furthermore, the extent to which Ca(2+)-permeable ion channels are functional in these tiny, anucleate cells is difficult to assess by direct electrophysiological measurements. Recent work has highlighted how the primary megakaryocyte represents a bona fide surrogate for studies of platelet signalling, including patch clamp recordings of ionic conductances. We have now screened for all known members of the transient receptor potential (TRP) family of non-selective cation channels in murine megakaryocytes following individual selection of these rare marrow cells using glass micropipettes. RT-PCR detected messages for TRPC6 and TRPC1, which have been reported in platelets and megakaryocytic cell lines, and TRPM1, TRPM2 and TRPM7, which to date have not been demonstrated in cells of megakaryocytic/platelet lineage. Electrophysiological recordings demonstrated the presence of functional TRPM7, a constitutively active cation channel sensitive to intracellular Mg(2+), and TRPM2, an ADP-ribose-dependent cation channel activated by oxidative stress. In addition, the electrophysiological and pharmacological properties of the non-selective cation channels stimulated by the physiological agonist ADP are consistent with a major role for TRPC6 in this G-protein-coupled receptor-dependent Ca(2+) influx pathway. This study defines for the first time the principal TRP channels within the primary megakaryocyte, which represent candidates for Ca(2+) influx pathways activated by a diverse range of stimuli in the platelet and megakaryocyte.
Collapse
Affiliation(s)
- Richard N Carter
- Department of Physiology, Development and Neuroscience, Physiology Building, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
| | | | | | | | | | | |
Collapse
|
535
|
Yoshida T, Inoue R, Morii T, Takahashi N, Yamamoto S, Hara Y, Tominaga M, Shimizu S, Sato Y, Mori Y. Nitric oxide activates TRP channels by cysteine S-nitrosylation. Nat Chem Biol 2006; 2:596-607. [PMID: 16998480 DOI: 10.1038/nchembio821] [Citation(s) in RCA: 421] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Accepted: 08/04/2006] [Indexed: 02/06/2023]
Abstract
Transient receptor potential (TRP) proteins form plasma-membrane cation channels that act as sensors for diverse cellular stimuli. Here, we report a novel activation mechanism mediated by cysteine S-nitrosylation in TRP channels. Recombinant TRPC1, TRPC4, TRPC5, TRPV1, TRPV3 and TRPV4 of the TRPC and TRPV families, which are commonly classified as receptor-activated channels and thermosensor channels, induce entry of Ca(2+) into cells in response to nitric oxide (NO). Labeling and functional assays using cysteine mutants, together with membrane sidedness in activating reactive disulfides, show that cytoplasmically accessible Cys553 and nearby Cys558 are nitrosylation sites mediating NO sensitivity in TRPC5. The responsive TRP proteins have conserved cysteines on the same N-terminal side of the pore region. Notably, nitrosylation of native TRPC5 upon G protein-coupled ATP receptor stimulation elicits entry of Ca(2+) into endothelial cells. These findings reveal the structural motif for the NO-sensitive activation gate in TRP channels and indicate that NO sensors are a new functional category of cellular receptors extending over different TRP families.
Collapse
Affiliation(s)
- Takashi Yoshida
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
536
|
Heiner I, Eisfeld J, Warnstedt M, Radukina N, Jüngling E, Lückhoff A. Endogenous ADP-ribose enables calcium-regulated cation currents through TRPM2 channels in neutrophil granulocytes. Biochem J 2006; 398:225-32. [PMID: 16719842 PMCID: PMC1550310 DOI: 10.1042/bj20060183] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TRPM2 (transient receptor potential melastatin 2) is a Ca2+-permeable cation channel gated by ADPR (ADP-ribose) from the cytosolic side. To test whether endogenous concentrations of intracellular ADPR are sufficient for TRPM2 gating in neutrophil granulocytes, we devised an HPLC method to determine ADPR contents in HClO4 cell extracts. The reversed-phase ion-pair HPLC method with an Mg2+-containing isocratic eluent allows baseline resolution of one ADPR peak. Intracellular ADPR concentrations were approx. 5 muM in granulocytes and not significantly altered by stimulation with the chemoattractant peptide fMLP (N-formylmethionyl-leucylphenylalanine). We furthermore determined intracellular concentrations of cADPR (cyclic ADPR) with a cyclase assay involving enzymatic conversion of cADPR into NAD+ and fluorimetric determination of NAD+. Intracellular cADPR concentrations were approx. 0.2 microM and not altered by fMLP. In patch-clamp experiments, ADPR (0.1-100 microM) was dialysed into granulocytes to analyse its effects on whole-cell currents characteristic for TRPM2, in the presence of a low (<10 nM) or a high (1 microM) intracellular Ca2+ concentration. TRPM2 currents were significantly larger at high than at low [Ca2+] (e.g. -225+/-27.1 versus -7+/-2.0 pA/pF at 5 muM ADPR), but no currents at all were observed in the absence of ADPR (ADPR concentration < or =0.3 microM). cADPR (0.1, 0.3 and 10 microM) was without effect even in the presence of subthreshold ADPR (0.1 microM). We conclude that ADPR enables an effective regulation of TRPM2 by cytosolic Ca2+. Thus ADPR and Ca2+ in concert behave as a messenger system for agonist-induced influx of Ca2+ through TRPM2 in granulocytes.
Collapse
Affiliation(s)
- Inka Heiner
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
| | - Jörg Eisfeld
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
| | - Maike Warnstedt
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
| | - Natalia Radukina
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
| | - Eberhard Jüngling
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
| | - Andreas Lückhoff
- Medical Faculty, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany
- To whom correspondence should be addressed (email )
| |
Collapse
|
537
|
Dietrich A, Chubanov V, Kalwa H, Rost BR, Gudermann T. Cation channels of the transient receptor potential superfamily: their role in physiological and pathophysiological processes of smooth muscle cells. Pharmacol Ther 2006; 112:744-60. [PMID: 16842858 DOI: 10.1016/j.pharmthera.2006.05.013] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 05/30/2006] [Indexed: 10/24/2022]
Abstract
Smooth muscle cells (SMC) are essential components of many tissues of the body. Ion channels regulate their membrane potential, the intracellular Ca(2+) concentration ([Ca(2+)](i)) and their contractility. Among the ion channels expressed in SMC cation channels of the transient receptor potential (TRP) superfamily allow the entry of Na(+), Ca(2+) and Mg(2+). Members of the TRP superfamily are essential constituents of tonically active channels (TAC), receptor-operated channels (ROC), store-operated channels (SOC) and stretch-activated channels (SAC). This review focusses on TRP channels (TRPC1, TRPC3, TRPC4, TRPC5, TRPC6, TRPC7, TRPV2, TRPV4, TRPM4, TRPM7, TRPP2) whose physiological functions in SMC were dissected by downregulating channel activity in isolated tissues or by the analysis of gene-deficient mouse models. Their possible functional role and physiological regulation as homomeric or heteromeric channels in SMC are discussed. Moreover, TRP channels may also be responsible for pathophysiological processes involving SMC-like airway hyperresponsiveness and pulmonary hypertension. Therefore, they present important drug targets for future pharmacological interventions.
Collapse
Affiliation(s)
- Alexander Dietrich
- Institut für Pharmakologie und Toxikologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 1, 35043 Marburg, Germany.
| | | | | | | | | |
Collapse
|
538
|
Mei ZZ, Mao HJ, Jiang LH. Conserved cysteine residues in the pore region are obligatory for human TRPM2 channel function. Am J Physiol Cell Physiol 2006; 291:C1022-8. [PMID: 16822940 PMCID: PMC1634803 DOI: 10.1152/ajpcell.00606.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TRPM2 proteins belong to the melastatin-related transient receptor potential or TRPM subfamily and form Ca(2+)-permeable cationic channels activated by intracellular adenosine diphosphoribose (ADPR). The TRPM2 channel subunit, like all its close relatives, is structurally homologous to the well-characterized voltage-gated potassium channel subunits, each containing six transmembrane segments and a putative pore loop between the fifth and sixth segments. Nevertheless, the structural elements determining the TRPM2 channel functions are still not well understood. In this study, we investigated the functional role of two conserved cysteine residues (at positions 996 and 1008) in the putative pore region of the human TRPM2 by site-directed mutagenesis, combined with electrophysiological and biochemical approaches. Expression of wild-type hTRPM2 channels in human embryonic kidney (HEK-293) cells resulted in robust ADPR-evoked currents. Substitution of cysteine with alanine or serine generated mutant channels that failed to be activated by ADPR. Furthermore, experiments done by Western blot analysis, immunocytochemistry, biotin labeling, and coimmunoprecipitation techniques showed no obvious changes in protein expression, trafficking or membrane localization, and the ability to interact with neighboring subunits that is required for channel assembly. Coexpression of wild-type and mutant subunits significantly reduced the ADPR-evoked currents; for the combination of wild-type and C996S mutant subunits, the reduction was approximately 95%, indicating that incorporation of one or more nonfunctional C996S subunits leads to the loss of channel function. These results taken together suggest that the cysteine residues in the pore region are obligatory for TRPM2 channel function.
Collapse
Affiliation(s)
- Zhu-Zhong Mei
- Institute of Membrane and Systems Biology, Faculty of
Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Hong-Ju Mao
- Institute of Membrane and Systems Biology, Faculty of
Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Lin-Hua Jiang
- Institute of Membrane and Systems Biology, Faculty of
Biological Sciences, University of Leeds, Leeds LS2 9JT, U.K
- Corresponding author: L-H Jiang, E-mail:
, Telephone: (+) 44 (0)113
343 4231, Fax: (+) 44 (0)113 343 4228
| |
Collapse
|
539
|
Ishii M, Shimizu S, Hagiwara T, Wajima T, Miyazaki A, Mori Y, Kiuchi Y. Extracellular-added ADP-ribose increases intracellular free Ca2+ concentration through Ca2+ release from stores, but not through TRPM2-mediated Ca2+ entry, in rat beta-cell line RIN-5F. J Pharmacol Sci 2006; 101:174-8. [PMID: 16766853 DOI: 10.1254/jphs.scj06001x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Intracellular ADP-ribose is an activator of TRPM2, which is a Ca2+-permeable channel and mediates H2O2-induced cell death, in the TRPM2-expressing rat beta-cell line RIN-5F. We examined the effect of extracellular-added ADP-ribose on intracellular Ca2+ concentration in RIN-5F cells. ADP-ribose induced Ca2+ release from the thapsigargin-sensitive Ca2+ store, but not Ca2+ entry across the plasma membrane. A phospholipase C (PLC) inhibitor and a non-specific IP3 receptor inhibitor blocked its Ca2+ release. H2O2-induced Ca2+ entry through TRPM2 was not affected by extracellular ADP-ribose. These findings suggest that extracellular-added ADP-ribose induces Ca2+ release through the PLC-IP3 pathway and does not act as a TRPM2 activator.
Collapse
Affiliation(s)
- Masakazu Ishii
- Department of Pathophysiology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
| | | | | | | | | | | | | |
Collapse
|
540
|
Abstract
The aim of this review is to provide a basic framework for understanding the function of mammalian transient receptor potential (TRP) channels, particularly as they have been elucidated in heterologous expression systems. Mammalian TRP channel proteins form six-transmembrane (6-TM) cation-permeable channels that may be grouped into six subfamilies on the basis of amino acid sequence homology (TRPC, TRPV, TRPM, TRPA, TRPP, and TRPML). Selected functional properties of TRP channels from each subfamily are summarized in this review. Although a single defining characteristic of TRP channel function has not yet emerged, TRP channels may be generally described as calcium-permeable cation channels with polymodal activation properties. By integrating multiple concomitant stimuli and coupling their activity to downstream cellular signal amplification via calcium permeation and membrane depolarization, TRP channels appear well adapted to function in cellular sensation. Our review of recent literature implicating TRP channels in neuronal growth cone steering suggests that TRPs may function more widely in cellular guidance and chemotaxis. The TRP channel gene family and its nomenclature, the encoded proteins and alternatively spliced variants, and the rapidly expanding pharmacology of TRP channels are summarized in online supplemental material.
Collapse
Affiliation(s)
- I Scott Ramsey
- Howard Hughes Medical Institute, Cardiovascular Department, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts 02115, USA.
| | | | | |
Collapse
|
541
|
Lund FE, Muller-Steffner H, Romero-Ramirez H, Moreno-García ME, Partida-Sánchez S, Makris M, Oppenheimer NJ, Santos-Argumedo L, Schuber F. CD38 induces apoptosis of a murine pro-B leukemic cell line by a tyrosine kinase-dependent but ADP-ribosyl cyclase- and NAD glycohydrolase-independent mechanism. Int Immunol 2006; 18:1029-42. [PMID: 16720618 DOI: 10.1093/intimm/dxl037] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cross-linking of CD38 on hematopoietic cells induces activation, proliferation and differentiation of mature T and B cells and mediates apoptosis of myeloid and lymphoid progenitor cells. In addition to acting as a signaling receptor, CD38 is also an enzyme capable of producing several calcium-mobilizing metabolites, including cyclic adenosine diphosphate ribose (cADPR). It has been previously postulated that the calcium-mobilizing metabolites produced by CD38 may regulate its receptor-based activities. To test this hypothesis, we examined whether the enzyme activity of CD38 controls the apoptosis of an anti-CD38-stimulated leukemic B cell. We show that anti-CD38-induced apoptosis of Ba/F3 cells, a murine pro-B cell line, is not affected by blocking the calcium-mobilizing activity of cADPR or by inhibiting intracellular or extracellular calcium mobilization. In addition, we demonstrate that blocking CD38 enzyme activity with 2'-deoxy-2'-fluoro-nicotinamide arabinoside adenine dinucleotide has no effect on apoptosis and that Ba/F3 cells expressing catalytically inactive mutant forms of CD38 still undergo apoptosis upon CD38 cross-linking. Instead, we find that anti-CD38-induced apoptosis is dependent on tyrosine kinase and caspase activation, and that this process appears to be potentiated by the presence of membrane microdomains. Thus, the receptor-mediated functions of CD38 can be separated from its enzyme activity in a murine leukemic cell line, suggesting that CD38 plays multiple, but independent, biologic roles.
Collapse
Affiliation(s)
- Frances E Lund
- Trudeau Institute, 154 Algonquin Avenue, Saranac Lake, NY 12983, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
542
|
Kou J, Klorig DC, Bloomquist JR. Potentiating effect of the ATP-sensitive potassium channel blocker glibenclamide on complex I inhibitor neurotoxicity in vitro and in vivo. Neurotoxicology 2006; 27:826-34. [PMID: 16725203 DOI: 10.1016/j.neuro.2006.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 04/10/2006] [Accepted: 04/14/2006] [Indexed: 12/21/2022]
Abstract
Previous studies have demonstrated a deficiency in mitochondrial function in Parkinson's disease. We measured the ability of mitochondrial inhibitors of complexes I (rotenone, MPP(+), and HPP(+)), II (amdro), IV (Na cyanide), and an uncoupler (dinoseb) to release preloaded dopamine from murine striatal synaptosomes. These compounds were potent dopamine releasers, and the effect was calcium-dependent. The striatum also contains a significant density of K(ATP)(+) channels, which play a protective role during ATP decline. Blockage of these channels with glibenclamide only potentiated the dopamine release by complex I inhibitors, and a selective potentiating effect of glibenclamide on the toxicity of MPTP was also observed, in vivo, using C57BL/6 mice. Western blots of striatal dopamine transporter (DAT) and tyrosine hydroxylase (TH) proteins demonstrated that 30 mg/kg of glibenclamide alone did not affect the expression of DAT and TH after two weeks of daily treatments, but it significantly enhanced the reduction of DAT and TH by a single dose of 20 mg/kg of MPTP. Amdro or dinoseb alone, or in conjunction with glibenclamide did not alter the expression of DAT and TH. The possible mechanisms underlying dopamine release and the selectivity of glibenclamide were further evaluated, in vitro. (86)Rb efflux assay showed that glibenclamide inhibited rotenone-induced K(+) efflux, but not dinoseb-induced K(+) efflux. Analysis of ATP titers in treated synaptosomes did not support a correlation between mitochondrial inhibition and K(ATP)(+) channel activation. However, assay of reactive oxygen species (ROS) showed that greater amounts of ROS generated by complex I inhibitors was a contributory factor to K(ATP)(+) channel activation and glibenclamide potentiation. Overall, these findings suggest that co-exposure to mitochondrial complex I inhibitors and glibenclamide or a genetic defect in K(ATP)(+) channel function, may increase neurotoxicity in the striatal dopaminergic system.
Collapse
Affiliation(s)
- Jinghong Kou
- Neurotoxicology Laboratory, Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | | | | |
Collapse
|
543
|
Miller BA. The role of TRP channels in oxidative stress-induced cell death. J Membr Biol 2006; 209:31-41. [PMID: 16685599 DOI: 10.1007/s00232-005-0839-3] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2005] [Indexed: 12/18/2022]
Abstract
The transient receptor potential (TRP) protein superfamily is a diverse group of voltage-independent calcium-permeable cation channels expressed in mammalian cells. These channels have been divided into six subfamilies, and two of them, TRPC and TRPM, have members that are widely expressed and activated by oxidative stress. TRPC3 and TRPC4 are activated by oxidants, which induce Na(+) and Ca(2+) entry into cells through mechanisms that are dependent on phospholipase C. TRPM2 is activated by oxidative stress or TNFalpha, and the mechanism involves production of ADP-ribose, which binds to an ADP-ribose binding cleft in the TRPM2 C-terminus. Treatment of HEK 293T cells expressing TRPM2 with H(2)O(2) resulted in Ca(2+) influx and increased susceptibility to cell death, whereas coexpression of the dominant negative isoform TRPM2-S suppressed H(2)O(2)-induced Ca(2+) influx, the increase in [Ca(2+)](i), and onset of apoptosis. U937-ecoR monocytic cells expressing increased levels of TRPM2 also exhibited significantly increased [Ca(2+)](i) and increased apoptosis after treatment with H(2)O(2) or TNFalpha. A dramatic increase in caspase 8, 9, 3, 7, and PARP cleavage was observed in TRPM2-expressing cells, demonstrating a downstream mechanism through which cell death is mediated. Inhibition of endogenous TRPM2 function through three approaches, depletion of TRPM2 by RNA interference, blockade of the increase in [Ca(2+)](i) through TRPM2 by calcium chelation, or expression of the dominant negative splice variant TRPM2-S protected cell viability. H(2)O(2) and amyloid beta-peptide also induced cell death in primary cultures of rat striatal cells, which endogenously express TRPM2. TRPM7 is activated by reactive oxygen species/nitrogen species, resulting in cation conductance and anoxic neuronal cell death, which is rescued by suppression of TRPM7 expression. TRPM2 and TRPM7 channels are physiologically important in oxidative stress-induced cell death.
Collapse
Affiliation(s)
- B A Miller
- The Department of Pediatrics, The Pennsylvania State University College of Medicine, P.O. Box 850, Hershey, 17033, USA.
| |
Collapse
|
544
|
Franco R, Bortner CD, Cidlowski JA. Potential Roles of Electrogenic Ion Transport and Plasma Membrane Depolarization in Apoptosis. J Membr Biol 2006; 209:43-58. [PMID: 16685600 DOI: 10.1007/s00232-005-0837-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2005] [Indexed: 12/15/2022]
Abstract
Apoptosis is characterized by the programmed activation of specific biochemical pathways leading to the organized demise of cells. To date, aspects of the intracellular signaling machinery involved in this phenomenon have been extensively dissected and characterized. However, recent studies have elucidated a novel role for changes in the intracellular milieu of the cells as important modulators of the cell death program. Specially, intracellular ionic homeostasis has been reported to be a determinant in both the activation and progression of the apoptotic cascade. Several apoptotic insults trigger specific changes in ionic gradients across the plasma membrane leading to depolarization of the plasma membrane potential (PMP). These changes lead to ionic imbalance early during apoptosis. Several studies have also suggested the activation and/or modulation of specific ionic transport mechanisms including ion channels, transporters and ATPases, as mediators of altered intracellular ionic homeostasis leading to PMP depolarization during apoptosis. However, the role of PMP depolarization and of the changes in ionic homeostasis during the progression of apoptosis are still unclear. This review summarizes the current knowledge regarding the causes and consequences of PMP depolarization during apoptosis. We also review the potential electrogenic ion transport mechanisms associated with this event, including the net influx/efflux of cations and anions. An understanding of these mechamisms could lead to the generation of new therapeutic approaches for a variety of diseases involving apoptosis.
Collapse
Affiliation(s)
- R Franco
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | | | |
Collapse
|
545
|
Togashi K, Hara Y, Tominaga T, Higashi T, Konishi Y, Mori Y, Tominaga M. TRPM2 activation by cyclic ADP-ribose at body temperature is involved in insulin secretion. EMBO J 2006. [PMID: 16601673 DOI: 10.1038/sj.ebmoj.7601083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There are eight thermosensitive TRP (transient receptor potential) channels in mammals, and there might be other TRP channels sensitive to temperature stimuli. Here, we demonstrate that TRPM2 can be activated by exposure to warm temperatures (>35 degrees C) apparently via direct heat-evoked channel gating. beta-NAD(+)- or ADP-ribose-evoked TRPM2 activity is robustly potentiated at elevated temperatures. We also show that, even though cyclic ADP-ribose (cADPR) does not activate TRPM2 at 25 degrees C, co-application of heat and intracellular cADPR dramatically potentiates TRPM2 activity. Heat and cADPR evoke similar responses in rat insulinoma RIN-5F cells, which express TRPM2 endogenously. In pancreatic islets, TRPM2 is coexpressed with insulin, and mild heating of these cells evokes increases in both cytosolic Ca(2+) and insulin release, which is K(ATP) channel-independent and protein kinase A-mediated. Heat-evoked responses in both RIN-5F cells and pancreatic islets are significantly diminished by treatment with TRPM2-specific siRNA. These results identify TRPM2 as a potential molecular target for cADPR, and suggest that TRPM2 regulates Ca(2+) entry into pancreatic beta-cells at body temperature depending on the production of cADPR-related molecules, thereby regulating insulin secretion.
Collapse
Affiliation(s)
- Kazuya Togashi
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Aichi, Japan
| | | | | | | | | | | | | |
Collapse
|
546
|
Togashi K, Hara Y, Tominaga T, Higashi T, Konishi Y, Mori Y, Tominaga M. TRPM2 activation by cyclic ADP-ribose at body temperature is involved in insulin secretion. EMBO J 2006; 25:1804-15. [PMID: 16601673 PMCID: PMC1456947 DOI: 10.1038/sj.emboj.7601083] [Citation(s) in RCA: 318] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 03/16/2006] [Indexed: 11/09/2022] Open
Abstract
There are eight thermosensitive TRP (transient receptor potential) channels in mammals, and there might be other TRP channels sensitive to temperature stimuli. Here, we demonstrate that TRPM2 can be activated by exposure to warm temperatures (>35 degrees C) apparently via direct heat-evoked channel gating. beta-NAD(+)- or ADP-ribose-evoked TRPM2 activity is robustly potentiated at elevated temperatures. We also show that, even though cyclic ADP-ribose (cADPR) does not activate TRPM2 at 25 degrees C, co-application of heat and intracellular cADPR dramatically potentiates TRPM2 activity. Heat and cADPR evoke similar responses in rat insulinoma RIN-5F cells, which express TRPM2 endogenously. In pancreatic islets, TRPM2 is coexpressed with insulin, and mild heating of these cells evokes increases in both cytosolic Ca(2+) and insulin release, which is K(ATP) channel-independent and protein kinase A-mediated. Heat-evoked responses in both RIN-5F cells and pancreatic islets are significantly diminished by treatment with TRPM2-specific siRNA. These results identify TRPM2 as a potential molecular target for cADPR, and suggest that TRPM2 regulates Ca(2+) entry into pancreatic beta-cells at body temperature depending on the production of cADPR-related molecules, thereby regulating insulin secretion.
Collapse
Affiliation(s)
- Kazuya Togashi
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Yuji Hara
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Tomoko Tominaga
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Tomohiro Higashi
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
| | - Yasunobu Konishi
- Department of Cellular and Molecular Physiology, Mie University School of Medicine, Mie, Japan
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Makoto Tominaga
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Japan
- Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Higashiyama 5-1, Myodaiji, Okazaki, Aichi 444-8787, Japan. Tel.: +81 564 59 5286; Fax: +81 564 59 5285; E-mail:
| |
Collapse
|
547
|
Beck A, Kolisek M, Bagley LA, Fleig A, Penner R. Nicotinic acid adenine dinucleotide phosphate and cyclic ADP-ribose regulate TRPM2 channels in T lymphocytes. FASEB J 2006; 20:962-4. [PMID: 16585058 DOI: 10.1096/fj.05-5538fje] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
TRPM2 (previously designated TRPC7 or LTRPC2) is a Ca2+-permeable nonselective cation channel that contains a C-terminal enzymatic domain with pyrophosphatase activity, which specifically binds ADP-ribose. Cyclic ADP-ribose (cADPR) and hydrogen peroxide (H2O2) can facilitate ADPR-mediated activation of heterologously expressed TRPM2. Here, we show that the two Ca2+-mobilizing second messengers cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) strongly activate natively expressed TRPM2 channels in Jurkat T cells. TRPM2 activation by both agonists can be partially suppressed by the ADPR antagonist adenosine monophosphate (AMP), which suggests that cADPR and NAADP lead to mobilization of endogenous ADPR presumably via metabolic conversion. The remaining channel activity is due to direct gating of TRPM2 by the two agonists and can be completely suppressed by 8-Br-cADPR, which suggests that cADPR and NAADP share a common binding site on TRPM2 that can regulate TRPM2 activity in synergy with ADPR. We conclude that cADPR and NAADP, in combination with ADPR, represent physiological co-activators of TRPM2 that contribute to Ca2+ influx in T lymphocytes and presumably other cell types that express this channel.
Collapse
Affiliation(s)
- Andreas Beck
- Laboratory of Cell and Molecular Signaling, Center for Biomedical Research, The Queen's Medical Center, 1301 Punchbowl St. UHT 8, Honolulu, Hawaii 96813, USA
| | | | | | | | | |
Collapse
|
548
|
Grubisha O, Rafty LA, Takanishi CL, Xu X, Tong L, Perraud AL, Scharenberg AM, Denu JM. Metabolite of SIR2 reaction modulates TRPM2 ion channel. J Biol Chem 2006; 281:14057-65. [PMID: 16565078 DOI: 10.1074/jbc.m513741200] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The transient receptor potential melastatin-related channel 2 (TRPM2) is a nonselective cation channel, whose prolonged activation by oxidative and nitrative agents leads to cell death. Here, we show that the drug puromycin selectively targets TRPM2-expressing cells, leading to cell death. Our data suggest that the silent information regulator 2 (Sir2 or sirtuin) family of enzymes mediates this susceptibility to cell death. Sirtuins are protein deacetylases that regulate gene expression, apoptosis, metabolism, and aging. These NAD+-dependent enzymes catalyze a reaction in which the acetyl group from substrate is transferred to the ADP-ribose portion of NAD+ to form deacetylated product, nicotinamide, and the metabolite OAADPr, whose functions remain elusive. Using cell-based assays and RNA interference, we show that puromycin-induced cell death is greatly diminished by nicotinamide (a potent sirtuin inhibitor), and by decreased expression of sirtuins SIRT2 and SIRT3. Furthermore, we demonstrate using channel current recordings and binding assays that OAADPr directly binds to the cytoplasmic domain of TRPM2 and activates the TRPM2 channel. ADP-ribose binds TRPM2 with similarly affinity, whereas NAD+ displays almost negligible binding. These studies provide the first evidence for the potential role of sirtuin-generated OAADPr in TRPM2 channel gating.
Collapse
Affiliation(s)
- Olivera Grubisha
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | | | | | | | | | | | | | | |
Collapse
|
549
|
Ishii M, Shimizu S, Hara Y, Hagiwara T, Miyazaki A, Mori Y, Kiuchi Y. Intracellular-produced hydroxyl radical mediates H2O2-induced Ca2+ influx and cell death in rat beta-cell line RIN-5F. Cell Calcium 2006; 39:487-94. [PMID: 16546253 DOI: 10.1016/j.ceca.2006.01.013] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 12/09/2005] [Accepted: 01/30/2006] [Indexed: 11/15/2022]
Abstract
The melastatin-related transient receptor potential channel TRPM2 is a Ca(2+)-permeable channel that is activated by H(2)O(2), and the Ca(2+) influx through TRPM2 mediates cell death. However, the responsible oxidants for TRPM2 activation remain to be identified. In the present study, we investigated the involvement of hydroxyl radical on TRPM2 activation in TRPM2-expressing HEK293 cells and the rat beta-cell line RIN-5F. In both cell types, H(2)O(2) induced Ca(2+) influx in a concentration-dependent manner. However, the addition of hydroxyl radical, which was produced by mixing FeSO(4) and H(2)O(2), to the cells, did not increase intracellular Ca(2+) concentration. Interestingly, when H(2)O(2) was added to the cells under intracellular Fe(2+)-accumulated conditions, Ca(2+) influx was markedly enhanced compared to H(2)O(2) alone. In addition, the H(2)O(2)-induced Ca(2+) influx was reduced by hydroxyl radical scavengers and an iron chelator. Under intracellular Fe(2+)-accumulated conditions, H(2)O(2)-induced RIN-5F cell death through TRPM2 activation was also markedly enhanced. Hydroxyl radical scavengers and an iron chelator suppressed the RIN-5F cell death by H(2)O(2). These results strongly suggest that the intracellular hydroxyl radical plays a key role in the activation of TRPM2 during H(2)O(2) treatment, and TRPM2 activation mediated by hydroxyl radical is implicated in H(2)O(2)-induced cell death in the beta-cell line RIN-5F.
Collapse
Affiliation(s)
- Masakazu Ishii
- Department of Pathophysiology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
| | | | | | | | | | | | | |
Collapse
|
550
|
Hsu MF, Chen YS, Huang LJ, Tsao LT, Kuo SC, Wang JP. GEA3162, a nitric oxide-releasing agent, activates non-store-operated Ca2+ entry and inhibits store-operated Ca2+ entry pathways in neutrophils through thiol oxidation. Eur J Pharmacol 2006; 535:43-52. [PMID: 16540105 DOI: 10.1016/j.ejphar.2006.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 02/03/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
We demonstrated that 5-amino-3-(3,4-dichlorophenyl)1,2,3,4-oxatriazolium (GEA3162), a nitric oxide (NO)-releasing agent, stimulated [Ca2+]i rise in rat neutrophils. This Ca2+ response was prevented by the thiol reducing agents, 2-mercaptoethanol, N-acetyl-L-cysteine, dithiothreitol, 2,3-dimercaptopropane-1-sulfonic acid (DMPS) and tris-(2-carboxyethyl)phosphine (TCEP), but slightly reduced by the antioxidant, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). GEA3162 also increased the formation of cellular reactive oxygen intermediates and decreased the cellular content of low molecular thiols. These responses were greatly reduced by Trolox, dithiothreitol and N-acetyl-L-cysteine. GEA3162 stimulated the protein tyrosine phosphorylation in neutrophils. The [Ca2+]i rise caused by formyl-Met-Leu-Phe (fMLP) and cyclopiazonic acid (CPA) was suppressed by GEA3162. TCEP prevented the inhibition of fMLP-induced [Ca2+]i rise by GEA3162. In the absence of external Ca2+, GEA3162 inhibited the CPA-induced [Ca2+]i rise, whereas it only slightly affected the fMLP-induced mobilization of the Ca2+ store. Application of GEA3162 after the stimulation with fMLP or CPA suppressed the robust Ca2+ entry followed by the readdition of Ca2+ into medium. Moreover, the Ca2+ entry was more susceptible to inhibition by treatment with GEA3162 prior to than after the fMLP stimulation. GEA3162 had no effect on the mitochondrial membrane potential. GEA3162 induced actin reorganization and condensed filament network at the cell periphery. These results indicate that GEA3162 exerted both the stimulation of Ca2+ entry and the inhibition of the store-operated Ca2+ entry in rat neutrophils. The dual effects of GEA3162 on the regulation of the external Ca2+ entry are mainly through the thiol modification of target protein(s) residing on the outside of the plasma membrane.
Collapse
Affiliation(s)
- Mei-Feng Hsu
- Department of Biochemistry, School of Medicine, China Medical University, Taichung, Taiwan, Republic of China
| | | | | | | | | | | |
Collapse
|