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Zong P, Li CX, Feng J, Cicchetti M, Yue L. TRP Channels in Stroke. Neurosci Bull 2023:10.1007/s12264-023-01151-5. [PMID: 37995056 DOI: 10.1007/s12264-023-01151-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/11/2023] [Indexed: 11/24/2023] Open
Abstract
Ischemic stroke is a devastating disease that affects millions of patients worldwide. Unfortunately, there are no effective medications for mitigating brain injury after ischemic stroke. TRP channels are evolutionally ancient biosensors that detect external stimuli as well as tissue or cellular injury. To date, many members of the TRP superfamily have been reported to contribute to ischemic brain injury, including the TRPC subfamily (1, 3, 4, 5, 6, 7), TRPV subfamily (1, 2, 3, 4) and TRPM subfamily (2, 4, 7). These TRP channels share structural similarities but have distinct channel functions and properties. Their activation during ischemic stroke can be beneficial, detrimental, or even both. In this review, we focus on discussing the interesting features of stroke-related TRP channels and summarizing the underlying cellular and molecular mechanisms responsible for their involvement in ischemic brain injury.
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Affiliation(s)
- Pengyu Zong
- Department of Cell Biology, Calhoun Cardiology Center, School of Medicine (UConn Health), University of Connecticut, Farmington, CT, 06030, USA.
- Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT, 06269, USA.
| | - Cindy X Li
- Department of Cell Biology, Calhoun Cardiology Center, School of Medicine (UConn Health), University of Connecticut, Farmington, CT, 06030, USA
| | - Jianlin Feng
- Department of Cell Biology, Calhoun Cardiology Center, School of Medicine (UConn Health), University of Connecticut, Farmington, CT, 06030, USA
| | - Mara Cicchetti
- Department of Cell Biology, Calhoun Cardiology Center, School of Medicine (UConn Health), University of Connecticut, Farmington, CT, 06030, USA
- Department of Neuroscience, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA, 15260, USA
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, School of Medicine (UConn Health), University of Connecticut, Farmington, CT, 06030, USA.
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Wei S, Behn J, Poore CP, Low SW, Nilius B, Fan H, Liao P. Binding epitope for recognition of human TRPM4 channel by monoclonal antibody M4M. Sci Rep 2022; 12:19562. [PMID: 36380063 PMCID: PMC9666640 DOI: 10.1038/s41598-022-22077-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
Mouse monoclonal antibody M4M was recently designed to block human TRPM4 channel. The polypeptide for generating M4M is composed of peptide A1 between the transmembrane segment 5 (S5) and the pore, and a second peptide A2 between the pore and the transmembrane segment 6 (S6). Using peptide microarray, a 4-amino acid sequence EPGF within the A2 was identified to be the binding epitope for M4M. Substitution of EPGF with other amino acids greatly reduced binding affinity. Structural analysis of human TRPM4 structure indicates that EPGF is located externally to the channel pore. A1 is close to the EPGF binding epitope in space, albeit separated by a 37-amino acid peptide. Electrophysiological study reveals that M4M could block human TRPM4, but with no effect on rodent TRPM4 which shares a different amino acid sequence ERGS for the binding motif. Our results demonstrate that M4M is a specific inhibitor for human TRPM4.
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Affiliation(s)
- Shunhui Wei
- grid.276809.20000 0004 0636 696XCalcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - Julian Behn
- grid.418325.90000 0000 9351 8132Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore, 138671 Singapore ,grid.4280.e0000 0001 2180 6431Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Charlene Priscilla Poore
- grid.276809.20000 0004 0636 696XCalcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - See Wee Low
- grid.276809.20000 0004 0636 696XCalcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - Bernd Nilius
- grid.5596.f0000 0001 0668 7884Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Hao Fan
- grid.418325.90000 0000 9351 8132Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), Singapore, 138671 Singapore
| | - Ping Liao
- grid.276809.20000 0004 0636 696XCalcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore ,grid.486188.b0000 0004 1790 4399Health and Social Sciences, Singapore Institute of Technology, Singapore, Singapore ,grid.428397.30000 0004 0385 0924Duke-NUS Medical School, Singapore, Singapore
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3
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Redel-Traub G, Sampson KJ, Kass RS, Bohnen MS. Potassium Channels as Therapeutic Targets in Pulmonary Arterial Hypertension. Biomolecules 2022; 12:1341. [PMID: 36291551 PMCID: PMC9599705 DOI: 10.3390/biom12101341] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/16/2022] [Accepted: 09/18/2022] [Indexed: 12/08/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is a devastating disease with high morbidity and mortality. Deleterious remodeling in the pulmonary arterial system leads to irreversible arterial constriction and elevated pulmonary arterial pressures, right heart failure, and eventually death. The difficulty in treating PAH stems in part from the complex nature of disease pathogenesis, with several signaling compounds known to be involved (e.g., endothelin-1, prostacyclins) which are indeed targets of PAH therapy. Over the last decade, potassium channelopathies were established as novel causes of PAH. More specifically, loss-of-function mutations in the KCNK3 gene that encodes the two-pore-domain potassium channel KCNK3 (or TASK-1) and loss-of-function mutations in the ABCC8 gene that encodes a key subunit, SUR1, of the ATP-sensitive potassium channel (KATP) were established as the first two potassium channelopathies in human cohorts with pulmonary arterial hypertension. Moreover, voltage-gated potassium channels (Kv) represent a third family of potassium channels with genetic changes observed in association with PAH. While other ion channel genes have since been reported in association with PAH, this review focuses on KCNK3, KATP, and Kv potassium channels as promising therapeutic targets in PAH, with recent experimental pharmacologic discoveries significantly advancing the field.
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Affiliation(s)
- Gabriel Redel-Traub
- Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Kevin J. Sampson
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Robert S. Kass
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Michael S. Bohnen
- Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
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Main Cations and Cellular Biology of Traumatic Spinal Cord Injury. Cells 2022; 11:cells11162503. [PMID: 36010579 PMCID: PMC9406880 DOI: 10.3390/cells11162503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/06/2022] [Accepted: 08/09/2022] [Indexed: 02/08/2023] Open
Abstract
Traumatic spinal cord injury is a life-changing condition with a significant socio-economic impact on patients, their relatives, their caregivers, and even the community. Despite considerable medical advances, there is still a lack of options for the effective treatment of these patients. The major complexity and significant disabling potential of the pathophysiology that spinal cord trauma triggers are the main factors that have led to incremental scientific research on this topic, including trying to describe the molecular and cellular mechanisms that regulate spinal cord repair and regeneration. Scientists have identified various practical approaches to promote cell growth and survival, remyelination, and neuroplasticity in this part of the central nervous system. This review focuses on specific detailed aspects of the involvement of cations in the cell biology of such pathology and on the possibility of repairing damaged spinal cord tissue. In this context, the cellular biology of sodium, potassium, lithium, calcium, and magnesium is essential for understanding the related pathophysiology and also the possibilities to counteract the harmful effects of traumatic events. Lithium, sodium, potassium—monovalent cations—and calcium and magnesium—bivalent cations—can influence many protein–protein interactions, gene transcription, ion channel functions, cellular energy processes—phosphorylation, oxidation—inflammation, etc. For data systematization and synthesis, we used the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) methodology, trying to make, as far as possible, some order in seeing the “big forest” instead of “trees”. Although we would have expected a large number of articles to address the topic, we were still surprised to find only 51 unique articles after removing duplicates from the 207 articles initially identified. Our article integrates data on many biochemical processes influenced by cations at the molecular level to understand the real possibilities of therapeutic intervention—which must maintain a very narrow balance in cell ion concentrations. Multimolecular, multi-cellular: neuronal cells, glial cells, non-neuronal cells, but also multi-ionic interactions play an important role in the balance between neuro-degenerative pathophysiological processes and the development of effective neuroprotective strategies. This article emphasizes the need for studying cation dynamics as an important future direction.
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Low SW, Gao Y, Wei S, Chen B, Nilius B, Liao P. Development and characterization of a monoclonal antibody blocking human TRPM4 channel. Sci Rep 2021; 11:10411. [PMID: 34002002 PMCID: PMC8129085 DOI: 10.1038/s41598-021-89935-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 05/04/2021] [Indexed: 02/06/2023] Open
Abstract
TRPM4 is a calcium-activated non-selective monovalent cation channel implicated in diseases such as stroke. Lack of potent and selective inhibitors remains a major challenge for studying TRPM4. Using a polypeptide from rat TRPM4, we have generated a polyclonal antibody M4P which could alleviate reperfusion injury in a rat model of stroke. Here, we aim to develop a monoclonal antibody that could block human TRPM4 channel. Two mouse monoclonal antibodies M4M and M4M1 were developed to target an extracellular epitope of human TRPM4. Immunohistochemistry and western blot were used to characterize the binding of these antibodies to human TRPM4. Potency of inhibition was compared using electrophysiological methods. We further evaluated the therapeutic potential on a rat model of middle cerebral artery occlusion. Both M4M and M4M1 could bind to human TRPM4 channel on the surface of live cells. Prolonged incubation with TRPM4 blocking antibody internalized surface TRPM4. Comparing to M4M1, M4M is more effective in blocking human TRPM4 channel. In human brain microvascular endothelial cells, M4M successfully inhibited TRPM4 current and ameliorated hypoxia-induced cell swelling. Using wild type rats, neither antibody demonstrated therapeutic potential on stroke. Human TRPM4 channel can be blocked by a monoclonal antibody M4M targeting a key antigenic sequence. For future clinical translation, the antibody needs to be humanized and a transgenic animal carrying human TRPM4 sequence is required for in vivo characterizing its therapeutic potential.
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Affiliation(s)
- See Wee Low
- Calcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Yahui Gao
- Calcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Shunhui Wei
- Calcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Bo Chen
- Calcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Bernd Nilius
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ping Liao
- Calcium Signalling Laboratory, Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore. .,Duke-NUS Medical School, Singapore, Singapore. .,Health and Social Sciences, Singapore Institute of Technology, Singapore, Singapore.
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Jimenez I, Prado Y, Marchant F, Otero C, Eltit F, Cabello-Verrugio C, Cerda O, Simon F. TRPM Channels in Human Diseases. Cells 2020; 9:E2604. [PMID: 33291725 PMCID: PMC7761947 DOI: 10.3390/cells9122604] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 12/11/2022] Open
Abstract
The transient receptor potential melastatin (TRPM) subfamily belongs to the TRP cation channels family. Since the first cloning of TRPM1 in 1989, tremendous progress has been made in identifying novel members of the TRPM subfamily and their functions. The TRPM subfamily is composed of eight members consisting of four six-transmembrane domain subunits, resulting in homomeric or heteromeric channels. From a structural point of view, based on the homology sequence of the coiled-coil in the C-terminus, the eight TRPM members are clustered into four groups: TRPM1/M3, M2/M8, M4/M5 and M6/M7. TRPM subfamily members have been involved in several physiological functions. However, they are also linked to diverse pathophysiological human processes. Alterations in the expression and function of TRPM subfamily ion channels might generate several human diseases including cardiovascular and neurodegenerative alterations, organ dysfunction, cancer and many other channelopathies. These effects position them as remarkable putative targets for novel diagnostic strategies, drug design and therapeutic approaches. Here, we review the current knowledge about the main characteristics of all members of the TRPM family, focusing on their actions in human diseases.
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Affiliation(s)
- Ivanka Jimenez
- Faculty of Life Science, Universidad Andrés Bello, Santiago 8370186, Chile; (I.J.); (Y.P.); (F.M.); (C.C.-V.)
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago 8380453, Chile;
| | - Yolanda Prado
- Faculty of Life Science, Universidad Andrés Bello, Santiago 8370186, Chile; (I.J.); (Y.P.); (F.M.); (C.C.-V.)
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago 8380453, Chile;
| | - Felipe Marchant
- Faculty of Life Science, Universidad Andrés Bello, Santiago 8370186, Chile; (I.J.); (Y.P.); (F.M.); (C.C.-V.)
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago 8380453, Chile;
| | - Carolina Otero
- Faculty of Medicine, School of Chemistry and Pharmacy, Universidad Andrés Bello, Santiago 8370186, Chile;
| | - Felipe Eltit
- Vancouver Prostate Centre, Vancouver, BC V6Z 1Y6, Canada;
- Department of Urological Sciences, University of British Columbia, Vancouver, BC V6Z 1Y6, Canada
| | - Claudio Cabello-Verrugio
- Faculty of Life Science, Universidad Andrés Bello, Santiago 8370186, Chile; (I.J.); (Y.P.); (F.M.); (C.C.-V.)
- Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Universidad de Santiago de Chile, Santiago 7560484, Chile
- Millennium Institute on Immunology and Immunotherapy, Santiago 8370146, Chile
| | - Oscar Cerda
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago 8380453, Chile;
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago 8380453, Chile
| | - Felipe Simon
- Faculty of Life Science, Universidad Andrés Bello, Santiago 8370186, Chile; (I.J.); (Y.P.); (F.M.); (C.C.-V.)
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago 8380453, Chile;
- Millennium Institute on Immunology and Immunotherapy, Santiago 8370146, Chile
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Rosenbaum MI, Clemmensen LS, Bredt DS, Bettler B, Strømgaard K. Targeting receptor complexes: a new dimension in drug discovery. Nat Rev Drug Discov 2020; 19:884-901. [PMID: 33177699 DOI: 10.1038/s41573-020-0086-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2020] [Indexed: 12/11/2022]
Abstract
Targeting receptor proteins, such as ligand-gated ion channels and G protein-coupled receptors, has directly enabled the discovery of most drugs developed to modulate receptor signalling. However, as the search for novel and improved drugs continues, an innovative approach - targeting receptor complexes - is emerging. Receptor complexes are composed of core receptor proteins and receptor-associated proteins, which have profound effects on the overall receptor structure, function and localization. Hence, targeting key protein-protein interactions within receptor complexes provides an opportunity to develop more selective drugs with fewer side effects. In this Review, we discuss our current understanding of ligand-gated ion channel and G protein-coupled receptor complexes and discuss strategies for their pharmacological modulation. Although such strategies are still in preclinical development for most receptor complexes, they exemplify how receptor complexes can be drugged, and lay the groundwork for this nascent area of research.
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Affiliation(s)
- Mette Ishøy Rosenbaum
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Louise S Clemmensen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - David S Bredt
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, CA, USA
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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Wei S, Low SW, Poore CP, Chen B, Gao Y, Nilius B, Liao P. Comparison of Anti-oncotic Effect of TRPM4 Blocking Antibody in Neuron, Astrocyte and Vascular Endothelial Cell Under Hypoxia. Front Cell Dev Biol 2020; 8:562584. [PMID: 33195194 PMCID: PMC7604339 DOI: 10.3389/fcell.2020.562584] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/30/2020] [Indexed: 12/31/2022] Open
Abstract
In stroke and other neurological diseases, Transient Receptor Potential Melastatin 4 (TRPM4) has been reported to cause oncotic cell death which is due to an excessive influx of sodium ions. Following stroke, hypoxia condition activates TRPM4 channel, and the sodium influx via TRPM4 is further enhanced by an increased TRPM4 expression. However, the effect of TRPM4 inhibition on oncotic cell death, particularly during the acute stage, remains largely unknown. Recently, we have developed a polyclonal antibody M4P that specifically inhibits TRPM4 channel. M4P blocks the channel via binding to a region close to the channel pore from extracellular space. Using M4P, we evaluated the acute effect of blocking TRPM4 in neurons, astrocytes, and vascular endothelial cells. In a rat stroke model, M4P co-localized with neuronal marker NeuN and endothelial marker vWF, whereas few GFAP positive astrocytes were stained by M4P in the ipsilateral hemisphere. When ATP was acutely depleted in cultured cortical neurons and microvascular endothelial cells, cell swelling was induced. Application of M4P significantly blocked TRPM4 current and attenuated oncosis. TUNEL assay, PI staining and western blot on cleaved Caspase-3 revealed that M4P could ameliorate apoptosis after 24 h hypoxia exposure. In contrast, acute ATP depletion in cultured astrocytes failed to demonstrate an increase of cell volume, and application of M4P or control IgG had no effect on cell volume change. When TRPM4 was overexpressed in astrocytes, acute ATP depletion successfully induced oncosis which could be suppressed by M4P treatment. Our results demonstrate that comparing to astrocytes, neurons, and vascular endothelial cells are more vulnerable to hypoxic injury. During the acute stage of stroke, blocking TRPM4 channel could protect neurons and vascular endothelial cells from oncotic cell death.
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Affiliation(s)
- Shunhui Wei
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore
| | - See Wee Low
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore
| | - Charlene Priscilla Poore
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore
| | - Bo Chen
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore
| | - Yahui Gao
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore
| | - Bernd Nilius
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ping Liao
- Calcium Signaling Laboratory, Department of Research, National Neuroscience Institute, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore.,Health and Social Sciences, Singapore Institute of Technology, Singapore, Singapore
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9
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TRPM4-specific blocking antibody attenuates reperfusion injury in a rat model of stroke. Pflugers Arch 2019; 471:1455-1466. [PMID: 31664513 PMCID: PMC6892354 DOI: 10.1007/s00424-019-02326-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 01/08/2023]
Abstract
Reperfusion therapy is currently the gold standard treatment for acute ischemic stroke. However, reperfusion injuries such as oedema and haemorrhagic transformation largely limit the use of this potent treatment to a narrow time window. Recently, transient receptor potential melastatin 4 (TRPM4) channel has emerged as a potential target for vascular protection in stroke management. Non-specificity and side effects are major concerns for current TRPM4 blockers. The present study was undertaken to develop a novel TRPM4 blocker for stroke management. We report the generation of a TRPM4-specific antibody M4P which binds to a region close to the channel pore. M4P could inhibit TRPM4 current and downregulate TRPM4 surface expression, therefore prevent hypoxia-induced cell swelling. In the rat model of 3-h stroke reperfusion, application of M4P at 2 h after occlusion ameliorated reperfusion injury by improving blood–brain barrier integrity, and enhanced functional recovery. Our results demonstrate that TRPM4 blockade could attenuate reperfusion injury in stroke recanalization. When applied together with reperfusion treatments, TRPM4 blocking antibody has the potential to extend the therapeutic time window for acute ischemic stroke.
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McClenaghan C, Woo KV, Nichols CG. Pulmonary Hypertension and ATP-Sensitive Potassium Channels. Hypertension 2019; 74:14-22. [PMID: 31132951 DOI: 10.1161/hypertensionaha.119.12992] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Conor McClenaghan
- From the Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO (C.M., C.G.N.)
| | - Kel Vin Woo
- Department of Pediatrics, Division of Cardiology, Washington University School of Medicine, St Louis, MO (K.V.W.)
| | - Colin G Nichols
- From the Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO (C.M., C.G.N.)
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11
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Gorse KM, Lantzy MK, Lee ED, Lafrenaye AD. Transient Receptor Potential Melastatin 4 Induces Astrocyte Swelling But Not Death after Diffuse Traumatic Brain Injury. J Neurotrauma 2018; 35:1694-1704. [PMID: 29390943 DOI: 10.1089/neu.2017.5275] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury (TBI) is a prevalent disease with significant costs. Although progress has been made in understanding the complex pathobiology of focal lesions associated with TBI, questions remain regarding the diffuse responses to injury. Expression of the transient receptor potential melastatin 4 (Trpm4) channel is linked to cytotoxic edema during hemorrhagic contusion expansion. However, little is known about Trpm4 following diffuse TBI. To explore Trpm4 expression in diffuse TBI, rats were subjected to a diffuse central fluid percussion injury (CFPI) and survived for 1.5 h to 8 weeks. The total number of Trpm4+ cells, as well as individual cellular intensity/expression of Trpm4, were assessed. Hemotoxylin and eosin (H&E) labeling was performed to evaluate cell damage/death potentially associated with Trpm4 expression following diffuse TBI. Finally, ultrastructural assessments were performed to evaluate the integrity of Trpm4+ cells and the potential for swelling associated with Trpm4 expression. Trpm4 was primarily restricted to astrocytes within the hippocampus and peaked at 6 h post-injury. While the number of Trpm4+ astrocytes returned to sham levels by 8 weeks post-CFPI, cellular intensity occurred in region-specific waves following injury. Correlative H&E assessments demonstrated little evidence of hippocampal damage, suggesting that Trpm4 expression by astrocytes does not precipitate cell death following diffuse TBI. Additionally, ultrastructural assessments showed Trpm4+ astrocytes exhibited twice the soma size compared with Trpm4- astrocytes, indicating that astrocyte swelling is associated with Trpm4 expression. This study provides a foundation for future investigations into the role of Trpm4 in astrocyte swelling and edema following diffuse TBI.
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Affiliation(s)
- Karen M Gorse
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
| | | | - Eun D Lee
- 3 Department of Obstetrics and Gynecology, Virginia Commonwealth University , Richmond, Virginia
| | - Audrey D Lafrenaye
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
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12
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Non-Invasive Multimodality Imaging Directly Shows TRPM4 Inhibition Ameliorates Stroke Reperfusion Injury. Transl Stroke Res 2018; 10:91-103. [PMID: 29569041 PMCID: PMC6327008 DOI: 10.1007/s12975-018-0621-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/22/2018] [Accepted: 03/08/2018] [Indexed: 10/30/2022]
Abstract
The transient receptor potential melastatin 4 (TRPM4) channel has been suggested to play a key role in the treatment of ischemic stroke. However, in vivo evaluation of TRPM4 channel, in particular by direct channel suppression, is lacking. In this study, we used multimodal imaging to assess edema formation and quantify the amount of metabolically functional brain salvaged after a rat model of stroke reperfusion. TRPM4 upregulation in endothelium emerges as early as 2 h post-stroke induction. Expression of TRPM4 channel was suppressed directly in vivo by treatment with siRNA; scrambled siRNA was used as a control. T2-weighted MRI suggests that TRPM4 inhibition successfully reduces edema by 30% and concomitantly salvages functionally active brain, measured by 18F-FDG-PET. These in vivo imaging results correlate well with post-mortem 2,3,5-triphenyltetrazolium chloride (TTC) staining which exhibits a 34.9% reduction in infarct volume after siRNA treatment. Furthermore, in a permanent stroke model, large areas of brain tissue displayed both edema and significant reductions in metabolic activity which was not shown in transient models with or without TRPM4 inhibition, indicating that tissue salvaged by TRPM4 inhibition during stroke reperfusion may survive. Evans Blue extravasation and hemoglobin quantification in the ipsilateral hemisphere were greatly reduced, suggesting that TRPM4 inhibition can improve BBB integrity after ischemic stroke reperfusion. Our results support the use of TRPM4 blocker for early stroke reperfusion.
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13
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Hu HJ, Song M. Disrupted Ionic Homeostasis in Ischemic Stroke and New Therapeutic Targets. J Stroke Cerebrovasc Dis 2017; 26:2706-2719. [PMID: 29054733 DOI: 10.1016/j.jstrokecerebrovasdis.2017.09.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Stroke is a leading cause of long-term disability. All neuroprotectants targeting excitotoxicity have failed to become stroke medications. In order to explore and identify new therapeutic targets for stroke, we here reviewed present studies of ionic transporters and channels that are involved in ischemic brain damage. METHOD We surveyed recent literature from animal experiments and clinical reports in the databases of PubMed and Elsevier ScienceDirect to analyze ionic mechanisms underlying ischemic cell damage and suggest promising ideas for stroke therapy. RESULTS Dysfunction of ionic transporters and disrupted ionic homeostasis are most early changes that underlie ischemic brain injury, thus receiving sustained attention in translational stroke research. The Na+/K+-ATPase, Na+/Ca2+ Exchanger, ionotropic glutamate receptor, acid-sensing ion channels (ASICs), sulfonylurea receptor isoform 1 (SUR1)-regulated NCCa-ATP channels, and transient receptor potential (TRP) channels are critically involved in ischemia-induced cellular degenerating processes such as cytotoxic edema, excitotoxicity, necrosis, apoptosis, and autophagic cell death. Some ionic transporters/channels also act as signalosomes to regulate cell death signaling. For acute stroke treatment, glutamate-mediated excitotoxicity must be interfered within 2 hours after stroke. The SUR1-regulated NCCa-ATP channels, Na+/K+-ATPase, ASICs, and TRP channels have a much longer therapeutic window, providing new therapeutic targets for developing feasible pharmacological treatments toward acute ischemic stroke. CONCLUSION The next generation of stroke therapy can apply a polypharmacology strategy for which drugs are designed to target multiple ion transporters/channels or their interaction with neurotoxic signaling pathways. But a successful translation of neuroprotectants relies on in-depth analyses of cell death mechanisms and suitable animal models resembling human stroke.
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Affiliation(s)
- Hui-Jie Hu
- Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mingke Song
- Department of Pharmacology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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15
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Guinamard R, Bouvagnet P, Hof T, Liu H, Simard C, Sallé L. TRPM4 in cardiac electrical activity. Cardiovasc Res 2015; 108:21-30. [PMID: 26272755 DOI: 10.1093/cvr/cvv213] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 07/31/2015] [Indexed: 11/12/2022] Open
Abstract
TRPM4 forms a non-selective cation channel activated by internal Ca(2+). Its functional expression was demonstrated in cardiomyocytes of several mammalian species including humans, but the channel is also present in many other tissues. The recent characterization of the TRPM4 inhibitor 9-phenanthrol, and the availability of transgenic mice have helped to clarify the role of TRPM4 in cardiac electrical activity, including diastolic depolarization from the sino-atrial node cells in mouse, rat, and rabbit, as well as action potential duration in mouse cardiomyocytes. In rat and mouse, pharmacological inhibition of TRPM4 prevents cardiac ischaemia-reperfusion injuries and decreases the occurrence of arrhythmias. Several studies have identified TRPM4 mutations in patients with inherited cardiac diseases including conduction blocks and Brugada syndrome. This review identifies TRPM4 as a significant actor in cardiac electrophysiology.
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Affiliation(s)
- Romain Guinamard
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | | | - Thomas Hof
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Hui Liu
- Department of Anatomy, Hainan Medical College, Haikou, Hainan 571101, China
| | - Christophe Simard
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
| | - Laurent Sallé
- Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, EA4650, Université de Caen Basse-Normandie, Sciences D, Esplanade de la Paix, CS 14032, 14032 Caen Cedex 5, France
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Garland CJ, Smirnov SV, Bagher P, Lim CS, Huang CY, Mitchell R, Stanley C, Pinkney A, Dora KA. TRPM4 inhibitor 9-phenanthrol activates endothelial cell intermediate conductance calcium-activated potassium channels in rat isolated mesenteric artery. Br J Pharmacol 2014; 172:1114-23. [PMID: 25323322 DOI: 10.1111/bph.12985] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/08/2014] [Accepted: 10/09/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Smooth muscle transient receptor potential melastatin 4 (TRPM4) channels play a fundamental role in the development of the myogenic arterial constriction that is necessary for blood flow autoregulation. As TRPM4 channels are present throughout the vasculature, we investigated their potential role in non-myogenic resistance arteries using the TRPM4 inhibitor 9-phenanthrol. EXPERIMENTAL APPROACH Pressure and wire myography were used to assess the reactivity of rat arteries, the latter in combination with measurements of smooth muscle membrane potential. Immunohistochemistry (IHC) and endothelial cell (EC) calcium changes were assessed in pressurized vessels and patch clamp measurements made in isolated ECs. KEY RESULTS The TRPM4 inhibitor 9-phenanthrol reversibly hyperpolarized mesenteric arteries to circa EK and blocked α1 -adrenoceptor-mediated vasoconstriction. Hyperpolarization was abolished and vasoconstriction re-established by damaging the endothelium. In mesenteric and cerebral artery smooth muscle, 9-phenanthrol hyperpolarization was effectively blocked by the KCa 3.1 inhibitor TRAM-34. 9-Phenanthrol did not increase mesenteric EC [Ca(2+)]i , and Na(+) substitution with N-methyl-D-glucamine only increased the muscle resting potential by 10 mV. Immunolabelling for TRPM4 was restricted to the endothelium and perivascular tissue. CONCLUSIONS AND IMPLICATIONS These data reveal a previously unrecognized action of the TRPM4 inhibitor 9-phenanthrol - the ability to act as an activator of EC KCa 3.1 channels. They do not indicate a functionally important role for TRPM4 channels in the reactivity of non-myogenic mesenteric arteries.
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Affiliation(s)
- C J Garland
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK
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Abstract
TRPM4 is a Ca(2+)-activated nonselective cation channel. The channel is activated by an increase of intracellular Ca(2+) and is regulated by several factors including temperature and Pi(4,5)P2. TRPM4 allows Na(+) entry into the cell upon activation, but is completely impermeable to Ca(2+). Unlike TRPM5, its closest relative in the transient receptor potential family, TRPM4 proteins are widely expressed in the body. Currents with properties that are reminiscent of TRPM4 have been described in a variety of tissues since the advent of the patch clamp technology, but their physiological role is only beginning to be clarified with the increasing characterization of knockout mouse models for TRPM4. Furthermore, mutations in the TRPM4 gene have been associated with cardiac conduction disorders in human patients. This review aims to overview the currently available data on the functional properties of TRPM4 and the current understanding of its physiological role in healthy and diseased tissue.
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Affiliation(s)
- Ilka Mathar
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, Herestraat 49, bus 802, 3000, Leuven, Belgium
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Nilius B, Flockerzi V. What do we really know and what do we need to know: some controversies, perspectives, and surprises. Handb Exp Pharmacol 2014; 223:1239-80. [PMID: 24961986 DOI: 10.1007/978-3-319-05161-1_20] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
TRP channels comprise one of the most rapid growing research topics in ion channel research, in fields related to ion channels including channelopathies and translational medicine. We provide here a critical survey on our current knowledge of TRP channels and highlight some of the still open or controversial questions. This comprises questions related to evolution of TRP channels; biophysics, i.e., permeation; pore properties and gating; modulation; the still-elusive 3D structure; and channel subunits but also their role as general sensory channels and in human diseases. We will conclude that our knowledge on TRP channels is still at the very beginning of an exciting research journey.
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Affiliation(s)
- Bernd Nilius
- Department Cell Mol Medicine, Laboratory Ion Channel Research, KU Leuven, Campus Gasthuisberg, O&N 1, Herestraat 49-Bus 802, 3000, Leuven, Belgium,
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Zhang ZR, Chu WF, Song B, Gooz M, Zhang JN, Yu CJ, Jiang S, Baldys A, Gooz P, Steele S, Owsianik G, Nilius B, Komlosi P, Bell PD. TRPP2 and TRPV4 form an EGF-activated calcium permeable channel at the apical membrane of renal collecting duct cells. PLoS One 2013; 8:e73424. [PMID: 23977387 PMCID: PMC3745395 DOI: 10.1371/journal.pone.0073424] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 07/19/2013] [Indexed: 01/26/2023] Open
Abstract
Objective Regulation of apical calcium entry is important for the function of principal cells of the collecting duct. However, the molecular identity and the regulators of the transporter/channel, which is responsible for apical calcium entry and what factors regulate the calcium conduction remain unclear. Methods and Results We report that endogenous TRPP2 and TRPV4 assemble to form a 23-pS divalent cation-permeable non-selective ion channel at the apical membrane of renal principal cells of the collecting duct. TRPP2\TRPV4 channel complex was identified by patch-clamp, immunofluorescence and co-immunprecipitation studies in both principal cells that either possess normal cilia (cilia (+)) or in which cilia are absent (cilia (-)). This channel has distinct biophysical and pharmacological and regulatory profiles compared to either TRPP2 or TRPV4 channels. The rate of occurrence detected by patch clamp was higher in cilia (-) compared to cilia (+) cells. In addition, shRNA knockdown of TRPP2 increased the prevalence of TRPV4 channel activity while knockdown of TRPV4 resulted in TRPP2 activity and knockdown of both proteins vastly decreased the 23-pS channel activity. Epidermal growth factor (EGF) stimulated TRPP2\TRPV4 channel through the EGF receptor (EGFR) tyrosine kinase-dependent signaling. With loss of cilia, apical EGF treatment resulted in 64-fold increase in channel activity in cilia (-) but not cilia (+) cells. In addition EGF increased cell proliferation in cilia (-) cell that was dependent upon TRPP2\TRPV4 channel mediated increase in intracellular calcium. Conclusion We conclude that in the absence of cilia, an EGF activated TRPP2\TRPV4 channel may play an important role in increased cell proliferation and cystogenesis.
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Affiliation(s)
- Zhi-Ren Zhang
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
- * E-mail: (PDB); (ZRZ)
| | - Wen-Feng Chu
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
| | - Binlin Song
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
| | - Monika Gooz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Jia-Ning Zhang
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
| | - Chang-Jiang Yu
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
| | - Shuai Jiang
- Departments of Pharmacy and Cardiology of the 2 Affiliated Hospital, Department of Pharmacology, Key Laboratories of Education Ministry for Myocardial Ischemia and Treatment, Harbin Medical University, Harbin, P. R. China
| | - Aleksander Baldys
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Pal Gooz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Stacy Steele
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Grzegorz Owsianik
- Department of Cellular and Molecular Medicine, Laboratory of Ion Channel Research, Campus Gasthuisberg, KU Leuven, Leuven, Belgium
| | - Bernd Nilius
- Department of Cellular and Molecular Medicine, Laboratory of Ion Channel Research, Campus Gasthuisberg, KU Leuven, Leuven, Belgium
| | - Peter Komlosi
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - P. Darwin Bell
- Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, United States of America
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail: (PDB); (ZRZ)
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Woo SK, Kwon MS, Ivanov A, Gerzanich V, Simard JM. The sulfonylurea receptor 1 (Sur1)-transient receptor potential melastatin 4 (Trpm4) channel. J Biol Chem 2012; 288:3655-67. [PMID: 23255597 PMCID: PMC3561583 DOI: 10.1074/jbc.m112.428219] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The sulfonylurea receptor 1 (Sur1)-NCCa-ATP channel plays a central role in necrotic cell death in central nervous system (CNS) injury, including ischemic stroke, and traumatic brain and spinal cord injury. Here, we show that Sur1-NCCa-ATP channels are formed by co-assembly of Sur1 and transient receptor potential melastatin 4 (Trpm4). Co-expression of Sur1 and Trpm4 yielded Sur1-Trpm4 heteromers, as shown in experiments with Förster resonance energy transfer (FRET) and co-immunoprecipitation. Co-expression of Sur1 and Trpm4 also yielded functional Sur1-Trpm4 channels with biophysical properties of Trpm4 and pharmacological properties of Sur1. Co-assembly with Sur1 doubled the affinity of Trpm4 for calmodulin and doubled its sensitivity to intracellular calcium. Experiments with FRET and co-immunoprecipitation showed de novo appearance of Sur1-Trpm4 heteromers after spinal cord injury in rats. Our findings depart from the long-held view of an exclusive association between Sur1 and KATP channels and reveal an unexpected molecular partnership with far-ranging implications for CNS injury.
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Affiliation(s)
- Seung Kyoon Woo
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Wang S, Makhina EN, Masia R, Hyrc KL, Formanack ML, Nichols CG. Domain organization of the ATP-sensitive potassium channel complex examined by fluorescence resonance energy transfer. J Biol Chem 2012; 288:4378-88. [PMID: 23223337 DOI: 10.1074/jbc.m112.388629] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
K(ATP) channels link cell metabolism to excitability in many cells. They are formed as tetramers of Kir6.2 subunits, each associated with a SUR1 subunit. We used mutant GFP-based FRET to assess domain organization in channel complexes. Full-length Kir6.2 subunits were linked to YFP or cyan fluorescent protein (CFP) at N or C termini, and all such constructs, including double-tagged YFP-Kir6.2-CFP (Y6.2C), formed functional K(ATP) channels. In intact COSm6 cells, background emission of YFP excited by 430-nm light was ∼6%, but the Y6.2C construct expressed alone exhibited an apparent FRET efficiency of ∼25%, confirmed by trypsin digestion, with or without SUR1 co-expression. Similar FRET efficiency was detected in mixtures of CFP- and YFP-tagged full-length Kir6.2 subunits and transmembrane domain only constructs, when tagged at the C termini but not at the N termini. The FRET-reported Kir6.2 tetramer domain organization was qualitatively consistent with Kir channel crystal structures: C termini and M2 domains are centrally located relative to N termini and M1 domains, respectively. Additional FRET analyses were performed on cells in which tagged full-length Kir6.2 and tagged SUR1 constructs were co-expressed. These analyses further revealed that 1) NBD1 of SUR1 is closer to the C terminus of Kir6.2 than to the N terminus; 2) the Kir6.2 cytoplasmic domain is not essential for complexation with SUR1; and 3) the N-terminal half of SUR1 can complex with itself in the absence of either the C-terminal half or Kir6.2.
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Affiliation(s)
- Shizhen Wang
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Abriel H, Syam N, Sottas V, Amarouch MY, Rougier JS. TRPM4 channels in the cardiovascular system: Physiology, pathophysiology, and pharmacology. Biochem Pharmacol 2012; 84:873-81. [DOI: 10.1016/j.bcp.2012.06.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/15/2012] [Accepted: 06/19/2012] [Indexed: 12/11/2022]
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Simard JM, Woo SK, Schwartzbauer GT, Gerzanich V. Sulfonylurea receptor 1 in central nervous system injury: a focused review. J Cereb Blood Flow Metab 2012; 32:1699-717. [PMID: 22714048 PMCID: PMC3434627 DOI: 10.1038/jcbfm.2012.91] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/03/2012] [Accepted: 05/09/2012] [Indexed: 01/13/2023]
Abstract
The sulfonylurea receptor 1 (Sur1)-regulated NC(Ca-ATP) channel is a nonselective cation channel that is regulated by intracellular calcium and adenosine triphosphate. The channel is not constitutively expressed, but is transcriptionally upregulated de novo in all cells of the neurovascular unit, in many forms of central nervous system (CNS) injury, including cerebral ischemia, traumatic brain injury (TBI), spinal cord injury (SCI), and subarachnoid hemorrhage (SAH). The channel is linked to microvascular dysfunction that manifests as edema formation and delayed secondary hemorrhage. Also implicated in oncotic cell swelling and oncotic (necrotic) cell death, the channel is a major molecular mechanism of 'accidental necrotic cell death' in the CNS. In animal models of SCI, pharmacological inhibition of Sur1 by glibenclamide, as well as gene suppression of Abcc8, prevents delayed capillary fragmentation and tissue necrosis. In models of stroke and TBI, glibenclamide ameliorates edema, secondary hemorrhage, and tissue damage. In a model of SAH, glibenclamide attenuates the inflammatory response due to extravasated blood. Clinical trials of an intravenous formulation of glibenclamide in TBI and stroke underscore the importance of recent advances in understanding the role of the Sur1-regulated NC(Ca-ATP) channel in acute ischemic, traumatic, and inflammatory injury to the CNS.
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Affiliation(s)
- J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA.
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