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Holderby KG, Kozak JA. Use of tetraethylammonium (TEA) and Tris loading for blocking TRPM7 channels in intact cells. Front Pharmacol 2024; 15:1341799. [PMID: 38659572 PMCID: PMC11039802 DOI: 10.3389/fphar.2024.1341799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 03/26/2024] [Indexed: 04/26/2024] Open
Abstract
Tetraethylammonium (TEA), a quaternary ammonium compound, is a well-known blocker of potassium channels belonging to various subfamilies, such as KV1-3, KCa1, 2 and prokaryotic KcsA. In many cases, TEA acts from the extracellular side by open pore blockade. TEA can also block transient receptor potential (TRP) cation channels, such as TRPM7, in a voltage-dependent manner. In human T lymphocytes, intracellular (cytosolic) TEA and its analog TMA (tetramethylammonium) inhibit TRPM7 channel currents in the outward but not inward direction. By contrast, intracellular Mg2+, protons and polyamines inhibit both outward and inward current components equally. Likewise, the majority of available pharmacological tools inhibit TRPM7 channels in a voltage-independent manner. Since TRPM7 is a steeply outwardly rectifying conductance, voltage-dependent blockers can be useful for studying the cellular functions of this channel. TRPM7 protein is endogenously expressed in diverse cell lines, including HEK, HeLa, CHO, RBL and Jurkat. Using patch-clamp electrophysiology, we found that incubating HEK293 and Jurkat T cells overnight in the presence of 20 mM TEA-Cl, resulted in the nearly complete blockade of whole-cell TRPM7 outward current, measured at break-in. By contrast, the inward current was unchanged in TEA-loaded cells. The blockade was fully reversible after washout of intracellular solution in whole-cell but not in perforated-patch recording configurations. Overnight incubation with 20 mM TMA-Cl resulted in a more modest blockade of the outward TRPM7 current. Internal 129 mM TMA and TEA eliminated most of the outward current. TEA uptake in transfected HEK293 cells led to blockade of recombinant murine TRPM7 and the Mg2+ and pH insensitive Ser1107Arg variant. Unexpectedly, Tris-HCl, a widely used pH buffer, could similarly be loaded into Jurkat and HEK cells, and preferentially blocked outward TRPM7 currents. 20 mM and 129 mM Tris in the internal solution blocked TRPM7 current in outward but not inward direction. Voltage-dependent channel blockade by TEA, TMA and Tris loading will be useful for studying the properties and functions of TRPM7-mediated ion transport in intact cells.
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Affiliation(s)
- Katherine G. Holderby
- Undergraduate Program in Physiology and Neuroscience, Dayton, OH, United States
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH, United States
| | - J. Ashot Kozak
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH, United States
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2
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Liu M, Dudley SC. Beyond Ion Homeostasis: Hypomagnesemia, Transient Receptor Potential Melastatin Channel 7, Mitochondrial Function, and Inflammation. Nutrients 2023; 15:3920. [PMID: 37764704 PMCID: PMC10536927 DOI: 10.3390/nu15183920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/02/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
As the second most abundant intracellular divalent cation, magnesium (Mg2+) is essential for cell functions, such as ATP production, protein/DNA synthesis, protein activity, and mitochondrial function. Mg2+ plays a critical role in heart rhythm, muscle contraction, and blood pressure. A significant decline in Mg2+ intake has been reported in developed countries because of the increased consumption of processed food and filtered/deionized water, which can lead to hypomagnesemia (HypoMg). HypoMg is commonly observed in cardiovascular diseases, such as heart failure, hypertension, arrhythmias, and diabetic cardiomyopathy, and HypoMg is a predictor for cardiovascular and all-cause mortality. On the other hand, Mg2+ supplementation has shown significant therapeutic effects in cardiovascular diseases. Some of the effects of HypoMg have been ascribed to changes in Mg2+ participation in enzyme activity, ATP stabilization, enzyme kinetics, and alterations in Ca2+, Na+, and other cations. In this manuscript, we discuss new insights into the pathogenic mechanisms of HypoMg that surpass previously described effects. HypoMg causes mitochondrial dysfunction, oxidative stress, and inflammation. Many of these effects can be attributed to the HypoMg-induced upregulation of a Mg2+ transporter transient receptor potential melastatin 7 channel (TRMP7) that is also a kinase. An increase in kinase signaling mediated by HypoMg-induced TRPM7 transcriptional upregulation, independently of any change in Mg2+ transport function, likely seems responsible for many of the effects of HypoMg. Therefore, Mg2+ supplementation and TRPM7 kinase inhibition may work to treat the sequelae of HypoMg by preventing increased TRPM7 kinase activity rather than just altering ion homeostasis. Since many diseases are characterized by oxidative stress or inflammation, Mg2+ supplementation and TRPM7 kinase inhibition may have wider implications for other diseases by acting to reduce oxidative stress and inflammation.
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Affiliation(s)
- Man Liu
- Cardiovascular Division, Department of Medicine, The Lillehei Heart Institute, University of Minnesota at Twin Cities, Minneapolis, MN 55455, USA;
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3
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Zhang M, Ma Y, Ye X, Zhang N, Pan L, Wang B. TRP (transient receptor potential) ion channel family: structures, biological functions and therapeutic interventions for diseases. Signal Transduct Target Ther 2023; 8:261. [PMID: 37402746 DOI: 10.1038/s41392-023-01464-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/26/2023] [Accepted: 04/25/2023] [Indexed: 07/06/2023] Open
Abstract
Transient receptor potential (TRP) channels are sensors for a variety of cellular and environmental signals. Mammals express a total of 28 different TRP channel proteins, which can be divided into seven subfamilies based on amino acid sequence homology: TRPA (Ankyrin), TRPC (Canonical), TRPM (Melastatin), TRPML (Mucolipin), TRPN (NO-mechano-potential, NOMP), TRPP (Polycystin), TRPV (Vanilloid). They are a class of ion channels found in numerous tissues and cell types and are permeable to a wide range of cations such as Ca2+, Mg2+, Na+, K+, and others. TRP channels are responsible for various sensory responses including heat, cold, pain, stress, vision and taste and can be activated by a number of stimuli. Their predominantly location on the cell surface, their interaction with numerous physiological signaling pathways, and the unique crystal structure of TRP channels make TRPs attractive drug targets and implicate them in the treatment of a wide range of diseases. Here, we review the history of TRP channel discovery, summarize the structures and functions of the TRP ion channel family, and highlight the current understanding of the role of TRP channels in the pathogenesis of human disease. Most importantly, we describe TRP channel-related drug discovery, therapeutic interventions for diseases and the limitations of targeting TRP channels in potential clinical applications.
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Affiliation(s)
- Miao Zhang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
- The Center for Microbes, Development and Health; Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yueming Ma
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Xianglu Ye
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Ning Zhang
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Lei Pan
- The Center for Microbes, Development and Health; Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, 200031, China.
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Bing Wang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
- Center for Pharmaceutics Research, Shanghai Institute of Materia Medica Chinese Academy of Sciences, Shanghai, 201203, China.
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4
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Andriulė I, Pangonytė D, Gwanyanya A, Karčiauskas D, Mubagwa K, Mačianskienė R. Detection of TRPM6 and TRPM7 Proteins in Normal and Diseased Cardiac Atrial Tissue and Isolated Cardiomyocytes. Int J Mol Sci 2022; 23:ijms232314860. [PMID: 36499188 PMCID: PMC9736228 DOI: 10.3390/ijms232314860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/02/2022] Open
Abstract
Magnesium-sensitive transient receptor potential melastatin (TRPM) ion channels, TRPM6 and TRPM7, are present in several organs, but their roles in the heart remain unclear. Therefore, here, we studied the expression patterns of TRPM6 and TRPM7 in normal and diseased myocardium. Cardiac atrial tissue and cardiomyocytes were obtained from healthy pigs and undiseased human hearts as well as from hearts of patients with ischemic heart disease (IHD) or atrial fibrillation (AF). Immunofluorescence and ELISA were used to detect TRP proteins. TRPM6 and TRPM7 immunofluorescence signals, localized at/near the cell surface or intracellularly, were detected in pig and human atrial tissues. The TRP channel modulators carvacrol (CAR, 100 µM) or 2-aminoethoxydiphenyl borate (2-APB, 500 µM) decreased the TRPM7 signal, but enhanced that of TRPM6. At a higher concentration (2 mM), 2-APB enhanced the signals of both proteins. TRPM6 and TRPM7 immunofluorescence signals and protein concentrations were increased in atrial cells and tissues from IHD or AF patients. TRPM6 and TRPM7 proteins were both detected in cardiac atrial tissue, with relatively similar subcellular localization, but distinctive drug sensitivity profiles. Their upregulated expression in IHD and AF suggests a possible role of the channels in cardiac atrial disease.
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Affiliation(s)
- Inga Andriulė
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania
| | - Dalia Pangonytė
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania
| | - Asfree Gwanyanya
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town 7700, South Africa
| | - Dainius Karčiauskas
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania
- Department of Cardiac, Thoracic and Vascular Surgery, Hospital of Lithuanian University of Health Sciences Kauno Klinikos, 50161 Kaunas, Lithuania
| | - Kanigula Mubagwa
- Department of Cardiovascular Sciences, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
- Department of Basic Sciences, Faculty of Medicine, Université Catholique de Bukavu, Bukavu, Congo
| | - Regina Mačianskienė
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania
- Correspondence:
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Audero MM, Prevarskaya N, Fiorio Pla A. Ca2+ Signalling and Hypoxia/Acidic Tumour Microenvironment Interplay in Tumour Progression. Int J Mol Sci 2022; 23:ijms23137377. [PMID: 35806388 PMCID: PMC9266881 DOI: 10.3390/ijms23137377] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 01/18/2023] Open
Abstract
Solid tumours are characterised by an altered microenvironment (TME) from the physicochemical point of view, displaying a highly hypoxic and acidic interstitial fluid. Hypoxia results from uncontrolled proliferation, aberrant vascularization and altered cancer cell metabolism. Tumour cellular apparatus adapts to hypoxia by altering its metabolism and behaviour, increasing its migratory and metastatic abilities by the acquisition of a mesenchymal phenotype and selection of aggressive tumour cell clones. Extracellular acidosis is considered a cancer hallmark, acting as a driver of cancer aggressiveness by promoting tumour metastasis and chemoresistance via the selection of more aggressive cell phenotypes, although the underlying mechanism is still not clear. In this context, Ca2+ channels represent good target candidates due to their ability to integrate signals from the TME. Ca2+ channels are pH and hypoxia sensors and alterations in Ca2+ homeostasis in cancer progression and vascularization have been extensively reported. In the present review, we present an up-to-date and critical view on Ca2+ permeable ion channels, with a major focus on TRPs, SOCs and PIEZO channels, which are modulated by tumour hypoxia and acidosis, as well as the consequent role of the altered Ca2+ signals on cancer progression hallmarks. We believe that a deeper comprehension of the Ca2+ signalling and acidic pH/hypoxia interplay will break new ground for the discovery of alternative and attractive therapeutic targets.
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Affiliation(s)
- Madelaine Magalì Audero
- U1003—PHYCEL—Laboratoire de Physiologie Cellulaire, Inserm, University of Lille, Villeneuve d’Ascq, 59000 Lille, France; (M.M.A.); (N.P.)
- Laboratory of Cellular and Molecular Angiogenesis, Department of Life Sciences and Systems Biology, University of Turin, 10123 Turin, Italy
| | - Natalia Prevarskaya
- U1003—PHYCEL—Laboratoire de Physiologie Cellulaire, Inserm, University of Lille, Villeneuve d’Ascq, 59000 Lille, France; (M.M.A.); (N.P.)
| | - Alessandra Fiorio Pla
- U1003—PHYCEL—Laboratoire de Physiologie Cellulaire, Inserm, University of Lille, Villeneuve d’Ascq, 59000 Lille, France; (M.M.A.); (N.P.)
- Laboratory of Cellular and Molecular Angiogenesis, Department of Life Sciences and Systems Biology, University of Turin, 10123 Turin, Italy
- Correspondence: ; Tel.: +39-0116704660
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6
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Alatrag F, Amoni M, Kelly-Laubscher R, Gwanyanya A. Cardioprotective effect of fingolimod against calcium paradox-induced myocardial injury in the isolated rat heart. Can J Physiol Pharmacol 2022; 100:134-141. [PMID: 34559972 DOI: 10.1139/cjpp-2021-0381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fingolimod (FTY720) inhibits Ca2+-permeable, Mg2+-sensitive channels called transient receptor potential melastatin 7 (TRPM7), but its effects on Ca2+ paradox (CP) - induced myocardial damage has not been evaluated. We studied the effect of FTY720 on CP-induced myocardial damage and used other TRPM7 channel inhibitors nordihydroguaiaretic acid (NDGA) and Mg2+ to test if any effect of FTY720 was via TRPM7 inhibition. Langendorff-perfused Wistar rat hearts were treated with FTY720 or NDGA and subjected to a CP protocol consisting of Ca2+ depletion followed by Ca2+ repletion. Hearts of rats pre-treated with MgSO4 were also subjected to CP. Hemodynamic parameters were measured using an intraventricular balloon, and myocardial infarct size was quantified using triphenyltetrazolium chloride stain. TRPM7 proteins in ventricular tissue were detected using immunoblot analysis. FTY720, but not NDGA, decreased CP-induced infarct size. Both FTY720 and NDGA minimized the CP-induced elevation of left ventricular end-diastolic pressure, but only FTY720 ultimately improved ventricular developed pressure. Mg2+ pre-treatment had no effect on CP-induced infarct size, nor hemodynamic parameters during CP, nor the level of TRPM7 protein expression in ventricular tissue. Overall, FTY720 attenuated CP-induced myocardial damage, with potential therapeutic implications on Ca2+-mediated cardiotoxicity; however, the cardioprotective mechanism of FTY720 seems to be unrelated to TRPM7 channel modulation.
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Affiliation(s)
- Fatma Alatrag
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town, South Africa
| | - Matthew Amoni
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town, South Africa
| | - Roisin Kelly-Laubscher
- Department of Pharmacology and Therapeutics, The College of Medicine and Health, University College Cork, Ireland
- Department of Biological Sciences, Faculty of Science, University of Cape Town, Rondebosch 7700, Cape Town, South Africa
| | - Asfree Gwanyanya
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town, South Africa
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Gwanyanya A, Andriulė I, Istrate BM, Easmin F, Mubagwa K, Mačianskienė R. Modulation of the Cardiac Myocyte Action Potential by the Magnesium-Sensitive TRPM6 and TRPM7-like Current. Int J Mol Sci 2021; 22:ijms22168744. [PMID: 34445449 PMCID: PMC8395930 DOI: 10.3390/ijms22168744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/04/2021] [Accepted: 08/12/2021] [Indexed: 01/08/2023] Open
Abstract
The cardiac Mg2+-sensitive, TRPM6, and TRPM7-like channels remain undefined, especially with the uncertainty regarding TRPM6 expression in cardiomyocytes. Additionally, their contribution to the cardiac action potential (AP) profile is unclear. Immunofluorescence assays showed the expression of the TRPM6 and TRPM7 proteins in isolated pig atrial and ventricular cardiomyocytes, of which the expression was modulated by incubation in extracellular divalent cation-free conditions. In patch clamp studies of cells dialyzed with solutions containing zero intracellular Mg2+ concentration ([Mg2+]i) to activate the Mg2+-sensitive channels, raising extracellular [Mg2+] ([Mg2+]o) from the 0.9-mM baseline to 7.2 mM prolonged the AP duration (APD). In contrast, no such effect was observed in cells dialyzed with physiological [Mg2+]i. Under voltage clamp, in cells dialyzed with zero [Mg2+]i, depolarizing ramps induced an outward-rectifying current, which was suppressed by raising [Mg2+]o and was absent in cells dialyzed with physiological [Mg2+]i. In cells dialyzed with physiological [Mg2+]i, raising [Mg2+]o decreased the L-type Ca2+ current and the total delayed-rectifier current but had no effect on the APD. These results suggest a co-expression of the TRPM6 and TRPM7 proteins in cardiomyocytes, which are therefore the molecular candidates for the native cardiac Mg2+-sensitive channels, and also suggest that the cardiac Mg2+-sensitive current shortens the APD, with potential implications in arrhythmogenesis.
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Affiliation(s)
- Asfree Gwanyanya
- Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (A.G.); (B.M.I.); (F.E.); (K.M.)
- Department of Human Biology, University of Cape Town, Cape Town 7925, South Africa
| | - Inga Andriulė
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania;
| | - Bogdan M. Istrate
- Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (A.G.); (B.M.I.); (F.E.); (K.M.)
| | - Farjana Easmin
- Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (A.G.); (B.M.I.); (F.E.); (K.M.)
| | - Kanigula Mubagwa
- Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium; (A.G.); (B.M.I.); (F.E.); (K.M.)
- Department of Basic Sciences, Faculty of Medicine, Université Catholique de Bukavu, Bukavu, Congo
| | - Regina Mačianskienė
- Institute of Cardiology, Lithuanian University of Health Sciences, 50103 Kaunas, Lithuania;
- Correspondence:
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Andriulė I, Pangonytė D, Almanaitytė M, Patamsytė V, Kuprytė M, Karčiauskas D, Mubagwa K, Mačianskienė R. Evidence for the expression of TRPM6 and TRPM7 in cardiomyocytes from all four chamber walls of the human heart. Sci Rep 2021; 11:15445. [PMID: 34326388 PMCID: PMC8322396 DOI: 10.1038/s41598-021-94856-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/15/2021] [Indexed: 02/07/2023] Open
Abstract
The expression of the channels-enzymes TRPM6 and TRPM7 in the human heart remains poorly defined, and TRPM6 is generally considered not to be expressed in cardiomyocytes. We examined their expression at protein and mRNA levels using right atrial samples resected from patients (n = 72) with or without ischemic heart disease (IHD) and samples from all chamber walls of explanted human hearts (n = 9). TRPM6 and TRPM7 proteins were detected using immunofluorescence on isolated cardiomyocytes, ELISA on tissue homogenates, and immunostaining of cardiac tissue, whereas their mRNAs were detected by RT-qPCR. Both TRPM6 and TRPM7 were present in all chamber walls, with TRPM7 being more abundant. TRPM6 was co-expressed with TRPM7. The expression levels were dependent on cell incubation conditions (presence or absence of divalent cations, pH of the extracellular milieu, presence of TRP channel inhibitors 2-aminoethoxydiphenyl-borate and carvacrol). These drugs reduced TRPM7 immunofluorescence but increased that of TRPM6. TRPM6 and TRPM7 expression was increased in tissues from IHD patients. This is the first demonstration of the presence and co-expression of TRPM6 and TRPM7 in cardiomyocytes from all chamber walls of the human heart. The increased TRPM6 and TRPM7 expression in IHD suggests that the chanzymes are involved in the pathophysiology of the disease.
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Affiliation(s)
- Inga Andriulė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Dalia Pangonytė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Mantė Almanaitytė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Vaiva Patamsytė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Milda Kuprytė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Dainius Karčiauskas
- Department of Cardiac, Thoracic and Vascular Surgery, Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Kanigula Mubagwa
- Department of Cardiovascular Sciences, Faculty of Medicine, KU Leuven, Leuven, Belgium
- Department of Basic Sciences, Faculty of Medicine, Université Catholique de Bukavu, Bukavu, DR, Congo
| | - Regina Mačianskienė
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
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Li Q, Li Z, Fan Z, Yang Y, Lu C. Involvement of non‑coding RNAs in the pathogenesis of myocardial ischemia/reperfusion injury (Review). Int J Mol Med 2021; 47:42. [PMID: 33576444 PMCID: PMC7895537 DOI: 10.3892/ijmm.2021.4875] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 01/22/2021] [Indexed: 12/13/2022] Open
Abstract
Myocardial ischemia/reperfusion injury (MIRI) may cause myocardial stunning, reperfusion arrhythmia, no‑reflow phenomenon and lethal reperfusion injury, which has a significant effect on the prognosis of patients undergoing thrombolytic agent therapy and percutaneous coronary intervention. Increasing evidence suggests that apoptosis, innate inflammation, oxidative stress, calcium overload and autophagy are involved in the pathogenesis of MIRI. Recent advancements in RNA sequencing technologies and genome‑wide analyses led to the finding of small non‑coding RNAs (ncRNAs). ncRNAs modulate cellular processes such as signal transduction, transcription, chromatin remodeling and post‑transcriptional modification. The effects of ncRNAs on cellular biology is more considerable than initially expected, and thus ncRNAs have gained increasing attention and focus in modern medical research. There are several types of ncRNAs, such as microRNAs (miRNAs), long non‑coding RNAs (lncRNAs) and circular RNAs (circRNAs), which have been shown to regulate gene expression at the transcription, post‑transcription and epigenetic levels. Dysregulation of ncRNAs, including miRNAs, lncRNAs and circRNAs, may participate in the molecular mechanisms of MIRI. The present review summarizes the characteristics and biological roles of miRNAs, lncRNAs and circRNAs, with particular emphasis on their role in MIRI, which show the novel complexity of ischemic hearts and may offer valuable insights into the pathogenesis of MIRI.
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Affiliation(s)
- Qi Li
- School of Medicine, Nankai University, Tianjin 300071
- Department of Cardiology, Tianjin First Center Hospital, Tianjin 300192
| | - Zhuqing Li
- School of Medicine, Nankai University, Tianjin 300071
- Department of Cardiology, Tianjin First Center Hospital, Tianjin 300192
| | - Zhixing Fan
- Department of Cardiology, The First College of Clinical Medical Science, China Three Gorges University, Yichang, Hubei 443000
| | - Ying Yang
- Department of Cardiology, Beijing Tsinghua Changgeng Hospital, School of Clinical Medicine, Tsinghua University, Beijing 100084, P.R. China
| | - Chengzhi Lu
- School of Medicine, Nankai University, Tianjin 300071
- Department of Cardiology, Tianjin First Center Hospital, Tianjin 300192
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Tashiro M, Konishi M, Kobayashi R, Inoue H, Yokoyama U. TRPM7 silencing attenuates Mg 2+ influx in cardiac myoblasts, H9c2 cells. J Physiol Sci 2020; 70:47. [PMID: 33028185 PMCID: PMC10717136 DOI: 10.1186/s12576-020-00772-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/11/2020] [Indexed: 11/10/2022]
Abstract
TRPM7, a member of the melastatin subfamily of transient receptor potential channels, is suggested to be a potential candidate for a physiological Mg2+ channel. However, there is no direct evidence of Mg2+ permeation through endogenous TRPM7. To determine the physiological roles of TRPM7 in intracellular Mg2+ homeostasis, we measured the cytoplasmic free Mg2+ concentration ([Mg2+]i) in TRPM7-silenced H9c2 cells. [Mg2+]i was measured in a cluster of 8-10 cells using the fluorescent indicator, furaptra. TRPM7 silencing did not change [Mg2+]i in Ca2+-free Tyrode's solution containing 1 mM Mg2+. Increasing the extracellular Mg2+ to 92.5 mM raised [Mg2+]i in control cells (1.56 ± 0.19 mM) at 30 min, while this effect was significantly attenuated in TRPM7-silenced cells (1.12 ± 0.07 mM). The Mg2+ efflux driven by Na+ gradient was unaffected by TRPM7 silencing. These results suggest that TRPM7 regulates the rate of Mg2+ influx in H9c2 cells, although cytoplasmic Mg2+ homeostasis at basal conditions is unaffected by TRPM7 silencing.
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Affiliation(s)
- Michiko Tashiro
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
| | - Masato Konishi
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan
| | - Ryo Kobayashi
- Department of Microbiology, Tokyo Medical University, Tokyo, 160-8402, Japan
| | - Hana Inoue
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan
| | - Utako Yokoyama
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan
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Effect of Carvacrol, TRP Channels Modulator, on Cardiac Electrical Activity. BIOMED RESEARCH INTERNATIONAL 2020; 2020:6456805. [PMID: 32337263 PMCID: PMC7166271 DOI: 10.1155/2020/6456805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/14/2020] [Accepted: 03/11/2020] [Indexed: 01/18/2023]
Abstract
Despite the wide application of carvacrol (CAR) in medicines, dietary supplements, and foods, there is still insufficient electrophysiological data on the mechanisms of action of CAR, particularly with regard to heart function. Therefore, in this study, we attempted to elucidate whether CAR, whose inhibitory effect on both cardiac and vascular TRPM7 and L-type Ca2+ currents has been demonstrated previously, could modify cardiac electrical activity. We used a combination of optical mapping and microelectrode techniques to track the action potentials (APs) and the spread of electrical activity in a Langendorff-perfused rabbit heart model during atrial/endo/epicardial pacing. Simultaneously, ECG recordings were acquired. Because human trials on CAR are still lacking, we tested the action of CAR on human ventricular preparations obtained from explanted hearts. Activation time (AT), AP duration (APD), and conduction velocity maps were constructed. We demonstrated that at a low concentration (10 μM) of CAR, only marginal changes in the AP parameters were observed. At higher concentrations (≥100 μM), a decrease in AP upstroke velocity (dV/dtmax), suggesting inhibition of Na+ current, and APD (at 50 and 90% repolarization) was detected; also slowing in the spread of electrical signals via the atrioventricular node was observed, suggesting impaired functioning of Ca2+ channels. In addition, a decrease in the T-wave amplitude was seen on the ECG, suggesting an impaired repolarization process. Nevertheless, those changes occurred without a significant impact on the resting membrane potential and were reversible. We suggest that CAR might play a role in modulating cardiac electrical activity at high concentrations.
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Hilgemann DW. Control of cardiac contraction by sodium: Promises, reckonings, and new beginnings. Cell Calcium 2019; 85:102129. [PMID: 31835176 DOI: 10.1016/j.ceca.2019.102129] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 11/20/2019] [Accepted: 11/20/2019] [Indexed: 12/12/2022]
Abstract
Several generations of cardiac physiologists have verified that basal cardiac contractility depends strongly on the transsarcolemmal Na gradient, and the underlying molecular mechanisms that link cardiac excitation-contraction coupling (ECC) to the Na gradient have been elucidated in good detail for more than 30 years. In brief, small increases of cytoplasmic Na push cardiac (NCX1) Na/Ca exchangers to increase contractility by increasing the myocyte Ca load. Accordingly, basal cardiac contractility is expected to be physiologically regulated by pathways that modify the cardiac Na gradient and the function of Na transporters. Assuming that this expectation is correct, it remains to be elucidated how in detail signaling pathways affecting the cardiac Na gradient are controlled in response to changing cardiac output requirements. Some puzzle pieces that may facilitate progress are outlined in this short review. Key open issues include (1) whether the concept of local Na gradients is viable, (2) how in detail Na channels, Na transporters and Na/K pumps are regulated by lipids and metabolic processes, (3) the physiological roles of Na/K pump inactivation, and (4) the possibility that key diffusible signaling molecules remain to be discovered.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75235, USA.
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Hu Q, Wolfner MF. The Drosophila Trpm channel mediates calcium influx during egg activation. Proc Natl Acad Sci U S A 2019; 116:18994-19000. [PMID: 31427540 PMCID: PMC6754564 DOI: 10.1073/pnas.1906967116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Egg activation is the process in which mature oocytes are released from developmental arrest and gain competency for embryonic development. In Drosophila and other arthropods, eggs are activated by mechanical pressure in the female reproductive tract, whereas in most other species, eggs are activated by fertilization. Despite the difference in the trigger, Drosophila shares many conserved features with higher vertebrates in egg activation, including a rise of intracellular calcium in response to the trigger. In Drosophila, this calcium rise is initiated by entry of extracellular calcium due to opening of mechanosensitive ion channels and initiates a wave that passes across the egg prior to initiation of downstream activation events. Here, we combined inhibitor tests, germ-line-specific RNAi knockdown, and germ-line-specific CRISPR/Cas9 knockout to identify the Transient Receptor Potential (TRP) channel subfamily M (Trpm) as a critical channel that mediates the calcium influx and initiates the calcium wave during Drosophila egg activation. We observed a reduction in the proportion of eggs that hatched from trpm germ-line knockout mutant females, although eggs were able to complete some egg activation events including cell cycle resumption. Since a mouse ortholog of Trpm was recently reported also to be involved in calcium influx during egg activation and in further embryonic development, our results suggest that calcium uptake from the environment via TRPM channels is a deeply conserved aspect of egg activation.
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Affiliation(s)
- Qinan Hu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
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Airini R, Iordache F, Alexandru D, Savu L, Epureanu FB, Mihailescu D, Amuzescu B, Maniu H. Senescence-induced immunophenotype, gene expression and electrophysiology changes in human amniocytes. J Cell Mol Med 2019; 23:7233-7245. [PMID: 31478614 PMCID: PMC6815807 DOI: 10.1111/jcmm.14495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 05/21/2019] [Accepted: 05/26/2019] [Indexed: 12/23/2022] Open
Abstract
The aim of the study was to evidence replicative senescence‐induced changes in human amniocytes via flow cytometry, quantitative reverse‐transcription‐polymerase chain reaction (qRT‐PCR) and automated/manual patch‐clamp. Both cryopreserved and senescent amniocytes cultured in BIO‐AMF‐2 medium featured high percentages of pluripotency cell surface antigens SSEA‐1, SSEA‐4, TRA1‐60, TRA1‐81 (assessed by flow cytometry) and expression of pluripotency markers Oct4 (Pou5f1) and Nanog (by qRT‐PCR). We demonstrated in senescent vs cryopreserved amniocytes decreases in mesenchymal stem cell surface markers. Senescence‐associated β‐galactosidase stained only senescent amniocytes, and they showed no deoxyuridine incorporation. The gene expression profile revealed a secretory phenotype of senescent amniocytes (increased interleukin (IL)‐1α, IL‐6, IL‐8, transforming growth factor β, nuclear factor κB p65 expression), increases for cell cycle‐regulating genes (p16INK4A), cytoskeletal elements (β‐actin); HMGB1, c‐Myc, Bcl‐2 showed reduced changes and p21, MDM2 decreased. Via patch‐clamp we identified five ion current components: outward rectifier K+ current, an inactivatable component, big conductance Ca2+‐dependent K+ channels (BK) current fluctuations, Na+ current, and inward rectifier K+ current. Iberiotoxin 100 nmol/L blocked 71% of BK fluctuations, and lidocaine 200 μmol/L exerted use‐dependent Na+ current block. Transient receptor potential (TRP)M7‐like current density at −120 mV was significantly increased in senescent amniocytes. The proinflammatory profile acquired by senescent amniocytes in vitro may prevent their use in clinical therapies for immunosuppression, antiapoptotic and healing effects.
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Affiliation(s)
- Razvan Airini
- Department of Biophysics & Physiology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Florin Iordache
- Department of Regenerative Medicine, "N. Simionescu" Institute of Cell Biology and Pathology, Bucharest, Romania
| | - Dorin Alexandru
- Department of Regenerative Medicine, "N. Simionescu" Institute of Cell Biology and Pathology, Bucharest, Romania
| | - Lorand Savu
- Genetic Lab S.R.L., Bucharest, Romania.,Fundeni Clinical Institute, Bucharest, Romania
| | - Florin Bogdan Epureanu
- Department of Biophysics & Physiology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Dan Mihailescu
- Department of Biophysics & Physiology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Bogdan Amuzescu
- Department of Biophysics & Physiology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Horia Maniu
- Department of Regenerative Medicine, "N. Simionescu" Institute of Cell Biology and Pathology, Bucharest, Romania
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Zou ZG, Rios FJ, Montezano AC, Touyz RM. TRPM7, Magnesium, and Signaling. Int J Mol Sci 2019; 20:E1877. [PMID: 30995736 PMCID: PMC6515203 DOI: 10.3390/ijms20081877] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 12/17/2022] Open
Abstract
The transient receptor potential melastatin-subfamily member 7 (TRPM7) is a ubiquitously expressed chanzyme that possesses an ion channel permeable to the divalent cations Mg2+, Ca2+, and Zn2+, and an α-kinase that phosphorylates downstream substrates. TRPM7 and its homologue TRPM6 have been implicated in a variety of cellular functions and is critically associated with intracellular signaling, including receptor tyrosine kinase (RTK)-mediated pathways. Emerging evidence indicates that growth factors, such as EGF and VEGF, signal through their RTKs, which regulate activity of TRPM6 and TRPM7. TRPM6 is primarily an epithelial-associated channel, while TRPM7 is more ubiquitous. In this review we focus on TRPM7 and its association with growth factors, RTKs, and downstream kinase signaling. We also highlight how interplay between TRPM7, Mg2+ and signaling kinases influences cell function in physiological and pathological conditions, such as cancer and preeclampsia.
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Affiliation(s)
- Zhi-Guo Zou
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Centre, University of Glasgow, Glasgow G12 8TA, UK.
| | - Francisco J Rios
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Centre, University of Glasgow, Glasgow G12 8TA, UK.
| | - Augusto C Montezano
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Centre, University of Glasgow, Glasgow G12 8TA, UK.
| | - Rhian M Touyz
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Centre, University of Glasgow, Glasgow G12 8TA, UK.
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Current Structural Knowledge on the CNNM Family of Magnesium Transport Mediators. Int J Mol Sci 2019; 20:ijms20051135. [PMID: 30845649 PMCID: PMC6429129 DOI: 10.3390/ijms20051135] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 02/06/2023] Open
Abstract
The cyclin and cystathionine β-synthase (CBS) domain magnesium transport mediators, CNNMs, are key players in maintaining the homeostasis of magnesium in different organs. The human family includes four members, whose impaired activity causes diseases such as Jalili Syndrome or Familial Hypomagnesemia, but is also linked to neuropathologic disorders, altered blood pressure, and infertility. Recent findings demonstrated that CNNMs are associated with the highly oncogenic phosphatases of the regenerating liver to promote tumor growth and metastasis, which has attracted renewed focus on their potential exploitation as targets for cancer treatment. However, the exact function of CNNMs remains unclear and is subject to debate, proposed as either direct transporters, sensors, or homeostatic factors. This review gathers the current structural knowledge on the CNNM family, highlighting similarities and differences with the closely related structural partners such as the bacterial Mg2+/Co2+ efflux protein CorC and the Mg2+ channel MgtE.
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Wu HY, Wu JL, Ni ZL. Overexpression of microRNA-202-3p protects against myocardial ischemia-reperfusion injury through activation of TGF-β1/Smads signaling pathway by targeting TRPM6. Cell Cycle 2019; 18:621-637. [PMID: 30810438 PMCID: PMC6464590 DOI: 10.1080/15384101.2019.1580494] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs) have been found to act as key regulators in the pathogenesis of myocardial ischemic-reperfusion (I/R) injury. In this study, we explore the role and mechanism of microRNA-202-3p (miR-202-3p) in regulating cardiomyocyte apoptosis, in respective of the TGF-β1/Smads signaling pathway by targeting the transient receptor potential cation channel, subfamily M, member 6 (TRPM6). The targeting relationship between miR-202-3p and TRPM6 was verified by a dual-luciferase reporter gene assay. Sprague-Dawley rat models of myocardial I/R injury were initially established and treated with different mimics, inhibitors and siRNAs to test the effects of miR-202-3p and TRPM6 on myocardial I/R injury. The levels of inflammatory factors; IL-1β, IL-6, TNF-α as well as the degree of myocardial fibrosis and cardiomyocyte apoptosis were determined in rats transfected with different plasmids. TRPM6 was found to be the target of miR-202-3p. Up-regulated miR-202-3p or knockdown of TRPM-6 alleviated oxidative stress and inflammatory response, reduced ventricular mass, altered cardiac hemodynamics, suppressed myocardial infarction, attenuated cell apoptosis, and inhibited myocardial fibrosis. MiR-202-3p overexpression activates the TGF-β1/Smads signaling pathway by negatively regulating TRPM6 expression. Taken together, these findings suggest that miR-202-3p offers protection against ventricular remodeling after myocardial I/R injury via activation of the TGF-β1/Smads signaling pathway.
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Affiliation(s)
- Hui-Ying Wu
- a Department of Cardiovascular Medicine , Fuwai Central China Cardiovascular Hospital , Zhengzhou , P.R. China
| | - Jian-Li Wu
- b Medical School , Huanghe S & T University , Zhengzhou , P.R. China
| | - Zhan-Ling Ni
- a Department of Cardiovascular Medicine , Fuwai Central China Cardiovascular Hospital , Zhengzhou , P.R. China
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19
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Lu FM, Hilgemann DW. Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes. J Gen Physiol 2017; 149:727-749. [PMID: 28606910 PMCID: PMC5496509 DOI: 10.1085/jgp.201711780] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022] Open
Abstract
The Na/K pump exports cytoplasmic Na ions while importing K ions, and its activity is thought to be affected by restricted intracellular Na diffusion in cardiac myocytes. Lu and Hilgemann find instead that the pump can enter an inactivated state and that inactivation can be relieved by cytoplasmic Na. Decades ago, it was proposed that Na transport in cardiac myocytes is modulated by large changes in cytoplasmic Na concentration within restricted subsarcolemmal spaces. Here, we probe this hypothesis for Na/K pumps by generating constitutive transsarcolemmal Na flux with the Na channel opener veratridine in whole-cell patch-clamp recordings. Using 25 mM Na in the patch pipette, pump currents decay strongly during continuous activation by extracellular K (τ, ∼2 s). In contradiction to depletion hypotheses, the decay becomes stronger when pump currents are decreased by hyperpolarization. Na channel currents are nearly unchanged by pump activity in these conditions, and conversely, continuous Na currents up to 0.5 nA in magnitude have negligible effects on pump currents. These outcomes are even more pronounced using 50 mM Li as a cytoplasmic Na congener. Thus, the Na/K pump current decay reflects mostly an inactivation mechanism that immobilizes Na/K pump charge movements, not cytoplasmic Na depletion. When channel currents are increased beyond 1 nA, models with unrestricted subsarcolemmal diffusion accurately predict current decay (τ ∼15 s) and reversal potential shifts observed for Na, Li, and K currents through Na channels opened by veratridine, as well as for Na, K, Cs, Li, and Cl currents recorded in nystatin-permeabilized myocytes. Ion concentrations in the pipette tip (i.e., access conductance) track without appreciable delay the current changes caused by sarcolemmal ion flux. Importantly, cytoplasmic mixing volumes, calculated from current decay kinetics, increase and decrease as expected with osmolarity changes (τ >30 s). Na/K pump current run-down over 20 min reflects a failure of pumps to recover from inactivation. Simulations reveal that pump inactivation coupled with Na-activated recovery enhances the rapidity and effectivity of Na homeostasis in cardiac myocytes. In conclusion, an autoregulatory mechanism enhances cardiac Na/K pump activity when cytoplasmic Na rises and suppresses pump activity when cytoplasmic Na declines.
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Affiliation(s)
- Fang-Min Lu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX
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20
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Modulation of Human Cardiac TRPM7 Current by Extracellular Acidic pH Depends upon Extracellular Concentrations of Divalent Cations. PLoS One 2017; 12:e0170923. [PMID: 28129376 PMCID: PMC5271359 DOI: 10.1371/journal.pone.0170923] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 01/12/2017] [Indexed: 11/19/2022] Open
Abstract
TRPM7 channels participate in a variety of physiological/pathological processes. TRPM7 currents are modulated by protons but opposing effects of external pH (pHo) (potentiation vs inhibition) have been reported. TRPM7 has been less studied in human cardiomyocytes than in heart-derived non-cardiomyocyte cells. We used the whole-cell patch-clamp technique on isolated human atrial cardiomyocytes to investigate the impact of an acidic pHo on the TRPM7 current. With voltage-dependent and other ion channels inhibited, cardiomyocytes were challenged with external acidification in either the presence or the absence of extracellular divalent cations. TRPM7 outward and inward currents were increased by acidic pHo in extracellular medium containing Ca2+ and Mg2+, but suppressed by acidic pHo in the absence of extracellular Ca2+ and Mg2+. The potentiating effect in the presence of extracellular divalents occurred at pHo below 6 and was voltage-dependent. The inhibitory effect in the absence of extracellular divalents was already marked at pHo of 6 and was practically voltage-independent. TRPM7 current density was higher in cardiomyocytes from patients with history of coronary vascular disease and the difference compared to cardiomyocytes from patients without history of myocardial ischemia increased with acidic pHo. We demonstrate that proton-induced modification of TRPM7 currents depends on the presence of extracellular Ca2+ and Mg2+. Variability of the TRPM7 current density in human cardiomyocytes is related to the clinical history, being higher in atrial fibrillation and in ischemic cardiomyopathy.
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Yu T, Sun P, Hu Y, Ji Y, Zhou H, Zhang B, Tian Y, Wu J. A novel and simple fluorescence probe for detecting main group magnesium ion in HeLa cells and Arabidopsis. Biosens Bioelectron 2016; 86:677-682. [DOI: 10.1016/j.bios.2016.07.057] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 07/15/2016] [Accepted: 07/18/2016] [Indexed: 01/15/2023]
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Zhang YJ, Ma N, Su F, Liu H, Mei J. Increased TRPM6 expression in atrial fibrillation patients contribute to atrial fibrosis. Exp Mol Pathol 2015; 98:486-90. [PMID: 25796343 DOI: 10.1016/j.yexmp.2015.03.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 03/16/2015] [Indexed: 11/18/2022]
Abstract
BACKGROUND Transient receptor potential (TRP) family plays important roles in cardiovascular system. We investigated the relationship between transient receptor potential channel subfamily M6 (TRPM6) and atrial fibrosis in rheumatic heart disease patients with atrial fibrillation (AF). METHODS The right atrial tissue samples were obtained from 64 patients with rheumatic heart diseases who underwent heart valve replacement surgery, and composed of 34 sinus rhythm (SR) patients and 30 AF patients. Hematoxylin and Eosin (HE) staining was used to observe cross-sectional area (CSA) of myocardial cell. Masson staining and measurement of connective tissue growth factor (CTGF), transforming growth factor beta 1 (TGF-β 1), and collagen type I/III (Collagen I/III) were performed to determine atrial fibrosis. The mRNA and protein levels of TRPM6 were detected by real-time quantitative polymerase chain reaction (RT-PCR) and western blotting, respectively. RESULTS Marked increases were observed in CSA of myocardial cell and myocardial collagen volume fraction in AF group compared with the SR group (all P<0.05). The mRNA levels of myocardial fibrosis markers (CTGF, TGF-beta 1, Collagen I/III) in AF group increased significantly compared to the SR group (all P<0.05). TRPM6 mRNA and protein levels in AF group were elevated markedly in comparison with SR group (P<0.01). CONCLUSION These findings revealed that increased TRPM6 mRNA and protein levels may contribute to atrial fibrosis, and suggested that TRPM6 might be involved in AF development by promoting fibrogenesis.
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Affiliation(s)
- Yun-Jiao Zhang
- Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China
| | - Nan Ma
- Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China
| | - Feng Su
- Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China
| | - Hao Liu
- Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China
| | - Ju Mei
- Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China.
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Pottosin I, Delgado-Enciso I, Bonales-Alatorre E, Nieto-Pescador MG, Moreno-Galindo EG, Dobrovinskaya O. Mechanosensitive Ca2+-permeable channels in human leukemic cells: Pharmacological and molecular evidence for TRPV2. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:51-9. [DOI: 10.1016/j.bbamem.2014.09.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 01/09/2023]
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Zeng Z, Inoue K, Sun H, Leng T, Feng X, Zhu L, Xiong ZG. TRPM7 regulates vascular endothelial cell adhesion and tube formation. Am J Physiol Cell Physiol 2014; 308:C308-18. [PMID: 25472964 DOI: 10.1152/ajpcell.00275.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Transient receptor potential melastatin 7 (TRPM7) is a nonselective cation channel with an α-kinase domain in its COOH terminal, known to play a role in diverse physiological and pathological processes such as Mg2+ homeostasis, cell proliferation, and hypoxic neuronal injury. Increasing evidence suggests that TRPM7 contributes to the physiology/pathology of vascular systems. For example, we recently demonstrated that silencing TRPM7 promotes growth and proliferation and protects against hyperglycemia-induced injury in human umbilical vein endothelial cells (HUVECs). Here we investigated the potential effects of TRPM7 on morphology, adhesion, migration, and tube formation of vascular endothelial cells and the potential underlying mechanism. We showed that inhibition of TRPM7 function in HUVECs by silencing TRPM7 decreases the density of TRPM7-like current and cell surface area and inhibits cell adhesion to Matrigel. Silencing TRPM7 also promotes cell migration, wound healing, and tube formation. Further studies showed that the extracellular signal-regulated kinase (ERK) pathway is involved in the change of cell morphology and the increase in HUVEC migration induced by TRPM7 silencing. We also demonstrated that silencing TRPM7 enhances the phosphorylation of myosin light chain (MLC) in HUVECs, which might be involved in the enhancement of cell contractility and motility. Collectively, our data suggest that the TRPM7 channel negatively regulates the function of vascular endothelial cells. Further studies on the underlying mechanism may facilitate the development of the TRPM7 channel as a target for the therapeutic intervention of vascular diseases.
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Affiliation(s)
- Zhao Zeng
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Ministry of Health Key Laboratory of Thrombosis and Hemostasis, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China; and Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Koichi Inoue
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Huawei Sun
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Tiandong Leng
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Xuechao Feng
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
| | - Li Zhu
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Ministry of Health Key Laboratory of Thrombosis and Hemostasis, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Soochow University, Suzhou, China; and
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia
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Yu N, Jiang J, Yu Y, Li H, Huang X, Ma Y, Zhang L, Zou J, Zhang B, Chen S, Liu P. SLC41A1 knockdown inhibits angiotensin II-induced cardiac fibrosis by preventing Mg(2+) efflux and Ca(2+) signaling in cardiac fibroblasts. Arch Biochem Biophys 2014; 564:74-82. [PMID: 25263961 DOI: 10.1016/j.abb.2014.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/05/2014] [Accepted: 09/10/2014] [Indexed: 12/17/2022]
Abstract
Na(+)/Mg(2+) exchanger plays an important role in cardiovascular system, but the molecular mechanisms still largely remain unknown. The Solute Carrier family 41A1 (SLC41A1), a novel Mg(2+) transporter, recently was found to function as Na(+)/Mg(2+) exchanger, which mainly regulates the intracellular Mg(2+) ([Mg(2+)]i) homeostasis. Our present studies were designed to investigate whether SLC41A1 impacts on the fibrogenesis of cardiac fibroblasts under Ang II stimulation. Our results showed that quinidine, a prototypical inhibitor of Na(+)/Mg(2+) exchanger, inhibited Ang II-induced cardiac fibrosis via attenuating the overexpression of vital biomarkers of fibrosis, including connective tissue growth factor (CTGF), fibronectin (FN) and α-smooth muscle actin (α-SMA). In addition, quinidine also decreased the Ang II-mediated elevation of concentration of intracellular Ca(2+) ([Ca(2+)]i) and extrusion of intracellular Mg(2+). Meanwhile, silencing SLC41A1 by RNA interference also impaired the elevation of [Ca(2+)]i, [Mg(2+)]i efflux and the upregulation of CTGF, FN and α-SMA provoked by Ang II. Furthermore, we found that Ang II-mediated activation of NFATc4 translocation decreased in SLC41A1-siRNA cells. These results support the notion that rapid extrusion of intracellular Mg(2+) is mediated by SLC41A1 and provide the evidence that the intracellular free Ca(2+) concentration is influenced by extrusion of intracellular Mg(2+) which facilitates fibrosis reaction in cardiac fibroblasts.
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Affiliation(s)
- Na Yu
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Jianmin Jiang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Yang Yu
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Hong Li
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Xiaoyang Huang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Yunzi Ma
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Luankun Zhang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Jian Zou
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Boyu Zhang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China
| | - Shaorui Chen
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China.
| | - Peiqing Liu
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China; National and Local Joint Engineering Laboratory of Druggabilitiy Assessment and Evaluation, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, PR China.
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Inactivation of TRPM7 kinase activity does not impair its channel function in mice. Sci Rep 2014; 4:5718. [PMID: 25030553 PMCID: PMC4101474 DOI: 10.1038/srep05718] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/23/2014] [Indexed: 11/30/2022] Open
Abstract
Transient receptor potential (TRP) family channels are involved in sensory pathways and respond to various environmental stimuli. Among the members of this family, TRPM7 is a unique fusion of an ion channel and a C-terminus kinase domain that is highly expressed in immune cells. TRPM7 serves as a key molecule governing cellular Mg2+ homeostasis in mammals since its channel pore is permeable to Mg2+ ions and can act as a Mg2+ influx pathway. However, mechanistic links between its kinase activity and channel function have remained uncertain. In this study, we generated kinase inactive knock-in mutant mice by mutagenesis of a key lysine residue involved in Mg2+-ATP binding. These mutant mice were normal in development and general locomotor activity. In peritoneal macrophages isolated from adult animals the basal activity of TRPM7 channels prior to cytoplasmic Mg2+ depletion was significantly potentiated, while maximal current densities measured after Mg2+ depletion were unchanged in the absence of detectable kinase function. Serum total Ca2+ and Mg2+ levels were not significantly altered in kinase-inactive mutant mice. Our findings suggest that abolishing TRPM7 kinase activity does not impair its channel activity and kinase activity is not essential for regulation of mammalian Mg2+ homeostasis.
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Fujii T, Shindo Y, Hotta K, Citterio D, Nishiyama S, Suzuki K, Oka K. Design and Synthesis of a FlAsH-Type Mg2+ Fluorescent Probe for Specific Protein Labeling. J Am Chem Soc 2014; 136:2374-81. [DOI: 10.1021/ja410031n] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomohiko Fujii
- Graduate
School of Medicine, University of Tokyo, 7-3-1 Hong, Bunkyo-ku, Tokyo 113-0033, Japan
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Abstract
The channel kinases TRPM6 and TRPM7 are fusion proteins with an ion transport domain and an enzymatically active kinase domain. TRPM7 has been found in every mammalian tissue investigated to date. The two-in-one protein structure, the ubiquitous expression profile, and the protein's unique biophysical characteristics that enable divalent ion transport involve TRPM7 in a plethora of (patho)physiological processes. With its prominent role in cellular and systemic magnesium homeostasis, TRPM7 emerges as a key player in embryonic development, global ischemia, cardiovascular disease, and cancer.
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Affiliation(s)
- Andrea Fleig
- Center for Biomedical Research at The Queen's Medical Center, Honolulu, HI, USA,
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Bai JPF, Hausman E, Lionberger R, Zhang X. Modeling and simulation of the effect of proton pump inhibitors on magnesium homeostasis. 1. Oral absorption of magnesium. Mol Pharm 2012; 9:3495-505. [PMID: 23051182 DOI: 10.1021/mp300323q] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prolonged use of proton pump inhibitors has reportedly caused rare clinically symptomatic hypomagnesemia. A review of the literature suggests PPI drugs may impair intestinal magnesium absorption. With the goal of preventing PPI-induced hypomagnesemia, an oral absorption-centric model was developed by referencing literature data. Our modeling with human data reveals that magnesium absorption is substantial in the distal intestine. We then perform simulations by referring to the reported reduction in mid to distal intestinal pH caused by one week of oral esomeprazole, and to reported reduction of the divalent cation-sensitive current when the carboxyl side chains of glutamic and aspartic residues in the binding channels of TRPM6/TRPM7 were neutralized. Our simulations reveal that short-term PPI therapy may cause a very small reduction (5%) in the serum magnesium level, which is qualitatively consistent with the reported 1% reduction in magnesium absorption following 1 week of omeprazole in humans. Simulations provide insight into the benefit of frequent but small dose of magnesium supplementation in maintaining the serum magnesium level when magnesium deficiency occurs.
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Affiliation(s)
- Jane P F Bai
- Office of Generic Drugs, Office of Pharmaceutical Science, §Office of Pharmacovigilance and Epidemiology, Office of Surveillance and Epidemiology, and †Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation, Food and Drug Administration , Rockville, Maryland, United States
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Chubanov V, Mederos y Schnitzler M, Meißner M, Schäfer S, Abstiens K, Hofmann T, Gudermann T. Natural and synthetic modulators of SK (K(ca)2) potassium channels inhibit magnesium-dependent activity of the kinase-coupled cation channel TRPM7. Br J Pharmacol 2012; 166:1357-76. [PMID: 22242975 DOI: 10.1111/j.1476-5381.2012.01855.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential cation channel subfamily M member 7 (TRPM7) is a bifunctional protein comprising a TRP ion channel segment linked to an α-type protein kinase domain. TRPM7 is essential for proliferation and cell growth. Up-regulation of TRPM7 function is involved in anoxic neuronal death, cardiac fibrosis and tumour cell proliferation. The goal of this work was to identify non-toxic inhibitors of the TRPM7 channel and to assess the effect of blocking endogenous TRPM7 currents on the phenotype of living cells. EXPERIMENTAL APPROACH We developed an aequorin bioluminescence-based assay of TRPM7 channel activity and performed a hypothesis-driven screen for inhibitors of the channel. The candidates identified were further assessed electrophysiologically and in cell biological experiments. KEY RESULTS TRPM7 currents were inhibited by modulators of small conductance Ca²⁺ -activated K⁺ channels (K(Ca)2.1-2.3; SK) channels, including the antimalarial plant alkaloid quinine, CyPPA, dequalinium, NS8593, SKA31 and UCL 1684. The most potent compound NS8593 (IC₅₀ 1.6 µM) specifically targeted TRPM7 as compared with other TRP channels, interfered with Mg²⁺ -dependent regulation of TRPM7 channel and inhibited the motility of cultured cells. NS8593 exhibited full and reversible block of native TRPM7-like currents in HEK 293 cells, freshly isolated smooth muscle cells, primary podocytes and ventricular myocytes. CONCLUSIONS AND IMPLICATIONS This study reveals a tight overlap in the pharmacological profiles of TRPM7 and K(Ca)2.1-2.3 channels. NS8593 acts as a negative gating modulator of TRPM7 and is well-suited to study functional features and cellular roles of endogenous TRPM7.
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Affiliation(s)
- V Chubanov
- Walther-Straub-Institute of Pharmacology and Toxicology, University of Munich, Munich, Germany.
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Macianskiene R, Martisiene I, Zablockaite D, Gendviliene V. Characterization of Mg²⁺-regulated TRPM7-like current in human atrial myocytes. J Biomed Sci 2012; 19:75. [PMID: 22891975 PMCID: PMC3431234 DOI: 10.1186/1423-0127-19-75] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 08/07/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND TRPM7 (Transient Receptor Potential of the Melastatin subfamily) proteins are highly expressed in the heart, however, electrophysiological studies, demonstrating and characterizing these channels in human cardiomyocytes, are missing. METHODS We have used the patch clamp technique to characterize the biophysical properties of TRPM7 channel in human myocytes isolated from right atria small chunks obtained from 116 patients in sinus rhythm during coronary artery and valvular surgery. Under whole-cell voltage-clamp, with Ca²⁺ and K⁺ channels blocked, currents were generated by symmetrical voltage ramp commands to potentials between -120 and +80 mV, from a holding potential of -80 mV. RESULTS We demonstrate that activated native current has dual control by intracellular Mg²⁺ (free-Mg²⁺ or ATP-bound form), and shows up- or down-regulation by its low or high levels, respectively, displaying outward rectification in physiological extracellular medium. High extracellular Mg²⁺ and Ca²⁺ block the outward current, while Gd³⁺, SpM⁴⁺, 2-APB, and carvacrol inhibit both (inward and outward) currents. Besides, divalents also permeate the channel, and the efficacy sequence, at 20 mM, was Mg²⁺>Ni²⁺>Ca²⁺>Ba²⁺>Cd²⁺ for decreasing outward and Ni²⁺>Mg²⁺>Ba²⁺≥Ca²⁺>Cd²⁺ for increasing inward currents. The defined current bears many characteristics of heterologously expressed or native TRPM7 current, and allowed us to propose that current under study is TRPM7-like. However, the time of beginning and time to peak as well steady state magnitude (range from 1.21 to 11.63 pA/pF, n(cells/patients) = 136/77) of induced TRPM7-like current in atrial myocytes from different patients showed a large variability, while from the same sample of human atria all these parameters were very homogenous. We present new information that TRPM7-like current in human myocytes is less sensitive to Mg²⁺. In addition, in some myocytes (from 24 out of 77 patients) that current was already up-regulated at membrane rupture. CONCLUSIONS This study provides the first electrophysiological description of TRPM7-like current in native human atrial myocytes. Less sensitivity to intracellular Mg²⁺ suggests for channel operation under physiological conditions. The TRPM7-like current up-regulation indicates the pathophysiological evidence of that current in human heart.
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Affiliation(s)
- Regina Macianskiene
- Institute of Cardiology, Lithuanian University of Health Sciences, Sukileliu 17, LT-50009, Kaunas, Lithuania
| | - Irma Martisiene
- Institute of Cardiology, Lithuanian University of Health Sciences, Sukileliu 17, LT-50009, Kaunas, Lithuania
| | - Danguole Zablockaite
- Institute of Cardiology, Lithuanian University of Health Sciences, Sukileliu 17, LT-50009, Kaunas, Lithuania
| | - Vida Gendviliene
- Institute of Cardiology, Lithuanian University of Health Sciences, Sukileliu 17, LT-50009, Kaunas, Lithuania
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Zhang YH, Sun HY, Chen KH, Du XL, Liu B, Cheng LC, Li X, Jin MW, Li GR. Evidence for functional expression of TRPM7 channels in human atrial myocytes. Basic Res Cardiol 2012; 107:282. [PMID: 22802050 PMCID: PMC3442166 DOI: 10.1007/s00395-012-0282-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 06/15/2012] [Accepted: 07/05/2012] [Indexed: 12/16/2022]
Abstract
Transient receptor potential melastatin-7 (TRPM7) channels have been recently reported in human atrial fibroblasts and are believed to mediate fibrogenesis in human atrial fibrillation. The present study investigates whether TRPM7 channels are expressed in human atrial myocytes using whole-cell patch voltage-clamp, RT-PCR and Western blotting analysis. It was found that a gradually activated TRPM7-like current was recorded with a K+- and Mg2+-free pipette solution in human atrial myocytes. The current was enhanced by removing extracellular Ca2+ and Mg2+, and the current increase could be inhibited by Ni2+ or Ba2+. The TRPM7-like current was potentiated by acidic pH and inhibited by La3+ and 2-aminoethoxydiphenyl borate. In addition, Ca2+-activated TRPM4-like current was recorded in human atrial myocytes with the addition of the Ca2+ ionophore A23187 in bath solution. RT-PCR and Western immunoblot analysis revealed that in addition to TRPM4, TRPM7 channel current, mRNA and protein expression were evident in human atrial myocytes. Interestingly, TRPM7 channel protein, but not TRPM4 channel protein, was significantly increased in human atrial specimens from the patients with atrial fibrillation. Our results demonstrate for the first time that functional TRPM7 channels are present in human atrial myocytes, and the channel expression is upregulated in the atria with atrial fibrillation.
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Affiliation(s)
- Yan-Hui Zhang
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
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Gwanyanya A, Macianskiene R, Mubagwa K. Insights into the effects of diclofenac and other non-steroidal anti-inflammatory agents on ion channels. ACTA ACUST UNITED AC 2012; 64:1359-75. [PMID: 22943167 DOI: 10.1111/j.2042-7158.2012.01479.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES Diclofenac and other non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in the treatment of inflammation and pain. Most effects of NSAIDs are attributed to the inhibition of cyclooxygenases (COX). However, many NSAIDs may have other effects not related to COX, including the modulation of various ion channels. The clinical implications of the effects on channels are not fully understood. This review outlines the effects of NSAIDs, with special attention to diclofenac, on ion channels and highlights the possible underlying mechanisms. KEY FINDINGS NSAIDs have effects on channels such as inhibition, activation or changes in expression patterns. The channels affected include voltage-gated Na(+) , Ca(2+) , or K(+) channels, ligand-gated K(+) channels, transient receptor potential and other cation channels as well as chloride channels in several types of cells. The mechanisms of drug actions not related to COX inhibition may involve drug-channel interactions, interference with the generation of second messengers, changes in channel expression, or synergistic/antagonist interactions with other channel modulators. SUMMARY The effects on ion channels may account for novel therapeutic actions of NSAIDs or for adverse effects. Among the NSAIDs, diclofenac may serve as a template for developing new channel modulators and as a tool for investigating the actions of other drugs.
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Affiliation(s)
- Asfree Gwanyanya
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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35
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Chokshi R, Matsushita M, Kozak JA. Detailed examination of Mg2+ and pH sensitivity of human TRPM7 channels. Am J Physiol Cell Physiol 2012; 302:C1004-11. [PMID: 22301056 DOI: 10.1152/ajpcell.00422.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TRPM7 channel kinase is a protein highly expressed in cells of hematopoietic lineage, such as lymphocytes. Studies performed in native and heterologous expression systems have shown that TRPM7 forms nonselective cation channels functional in the plasma membrane and activated on depletion of cellular Mg(2+). In addition to internal Mg(2+), cytosolic pH and the phospholipid phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P(2)] are potent physiological regulators of this channel: protons inhibit, while PI(4,5)P(2) is required for TRPM7 channel activity. These channels are also inhibited from inside by other metal cations and polyamines. While the regulation of TRPM7 channels by internal metal ions, acidic pH, and PI(4,5)P(2) is voltage independent, extracellular metal cations and polyamines block voltage dependently at micromolar concentrations and appear to occupy a distinct blocking site. In the present study we investigated intracellular Mg(2+) and pH dependence of native TRPM7 currents using whole cell patch-clamp electrophysiology in human Jurkat T lymphocytes and HEK293 cells. Our main findings are 1) Mg(2+) inhibition involves not one but two separate sites of high (∼10 μM) and low (∼165 μM) affinity; and 2) while sharing certain characteristics with Mg(2+) inhibition, protons most likely inhibit through one inhibitory site, corresponding to the low-affinity Mg(2+) site, with an estimated IC(50) of pH 6.3. Additionally, we present data on amplitude distribution of preactivated TRPM7 currents in Jurkat T lymphocytes in the absence of prior Mg(2+) or proton depletion.
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Abstract
In the retina, light onset hyperpolarizes photoreceptors and depolarizes ON bipolar cells at the sign inverting photoreceptor-ON bipolar cell synapse. Transmission at this synapse is mediated by a signaling cascade comprised of mGluR6, a G-protein containing G(αo), and the cation channel TRP melastatin 1 (TRPM1). This system is thought to be common to both the rod- and ON-cone-driven pathways, which control vision under scotopic and photopic conditions, respectively. In this study, we present evidence that the rod pathway is uniquely susceptible to modulation by PKCα at the rod-rod bipolar cell synapse. Decreased production of DAG (an activator of PKC) by inhibition of PIP₂ (phosphatidylinositol-4,5-bisphosphate) hydrolysis caused depression of the TRPM1 current. Conversely, addition of a DAG analog, 2-acetyl-1-oleoyl-sn-glycerol (OAG), potentiated the current in rod bipolar cells but not in ON-cone bipolar cells. The potentiating effects of OAG were absent both in mutant mice that lack PKCα expression and in wild-type mice in which enzymatic activity of PKCα was pharmacologically inhibited. In addition, we found that, like other members of the TRPM subfamily, TRPM1 current is susceptible to voltage-independent inhibition by intracellular magnesium, and that modulation by PKCα relieves this inhibition, as the potentiating effects of OAG are absent in low intracellular magnesium. We conclude that activation of PKCα initiates a modulatory mechanism at the rod-rod bipolar cell synapse whose function is to reduce inhibition of the TRPM1 current by magnesium, thereby increasing the gain of transmission at this synapse.
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37
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Romani AMP. Cellular magnesium homeostasis. Arch Biochem Biophys 2011; 512:1-23. [PMID: 21640700 PMCID: PMC3133480 DOI: 10.1016/j.abb.2011.05.010] [Citation(s) in RCA: 354] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 12/12/2022]
Abstract
Magnesium, the second most abundant cellular cation after potassium, is essential to regulate numerous cellular functions and enzymes, including ion channels, metabolic cycles, and signaling pathways, as attested by more than 1000 entries in the literature. Despite significant recent progress, however, our understanding of how cells regulate Mg(2+) homeostasis and transport still remains incomplete. For example, the occurrence of major fluxes of Mg(2+) in either direction across the plasma membrane of mammalian cells following metabolic or hormonal stimuli has been extensively documented. Yet, the mechanisms ultimately responsible for magnesium extrusion across the cell membrane have not been cloned. Even less is known about the regulation in cellular organelles. The present review is aimed at providing the reader with a comprehensive and up-to-date understanding of the mechanisms enacted by eukaryotic cells to regulate cellular Mg(2+) homeostasis and how these mechanisms are altered under specific pathological conditions.
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Affiliation(s)
- Andrea M P Romani
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA.
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38
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Transient receptor proteins illuminated: Current views on TRPs and disease. Vet J 2011; 187:153-64. [DOI: 10.1016/j.tvjl.2010.01.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 01/21/2010] [Accepted: 01/25/2010] [Indexed: 11/23/2022]
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Dyachok O, Zhabyeyev P, McDonald TF. Electroporation-induced inward current in voltage-clamped guinea pig ventricular myocytes. J Membr Biol 2010; 238:69-80. [PMID: 21104181 DOI: 10.1007/s00232-010-9320-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 10/29/2010] [Indexed: 01/29/2023]
Abstract
Electroporation induced by high-strength electrical fields has long been used to investigate membrane properties and facilitate transmembrane delivery of molecules and genes for research and clinical purposes. In the heart, electric field-induced passage of ions through electropores is a factor in defibrillation and postshock dysfunction. Voltage-clamp pulses can also induce electroporation, as exemplified by findings in earlier studies on rabbit ventricular myocytes: Long hyperpolarizations to ≤-110 mV induced influx of marker ethidium and irregular inward currents that were as large with external NMDG(+) as Na(+). In the present study, guinea pig ventricular myocytes were bathed with NMDG(+), Na(+) or NMDG(+) + La(3+) solution (36°C) and treated with five channel blockers. Hyperpolarization of myocytes in NMDG(+) solution elicited an irregular inward current (I (ep)) that reversed at -21.5 ± 1.5 mV. In myocytes hyperpolarized with 200-ms steps every 30 s, I (ep) occurred in "episodes" that lasted for one to four steps. Boltzmann fits to data on the incidence of I (ep) per experiment indicate 50% incidence at -129.7 ± 1.4 mV (Na(+)) and -146.3 ± 1.6 mV (NMDG(+)) (slopes ≈-7.5 mV). I (ep) amplitude increased with negative voltage and was larger with Na(+) than NMDG(+) (e.g., -2.83 ± 0.34 vs. -1.40 ± 0.22 nA at -190 mV). La(3+) (0.2 mM) shortened episodes, shifted 50% incidence by -35 mV and decreased amplitude, suggesting that it inhibits opening/promotes closing of electropores. We compare our findings with earlier ones, especially in regard to electropore selectivity. In the Appendix, relative permeabilities and modified excluded-area theory are used to derive estimates of electropore diameters consistent with reversal potential -21.5 mV.
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Affiliation(s)
- Oksana Dyachok
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, B3H 1X5, Canada
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40
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Tashiro M, Inoue H, Konishi M. KB-R7943 inhibits Na+-dependent Mg2+ efflux in rat ventricular myocytes. J Physiol Sci 2010; 60:415-24. [PMID: 20862573 PMCID: PMC10717662 DOI: 10.1007/s12576-010-0113-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 08/26/2010] [Indexed: 11/29/2022]
Abstract
Na(+)-dependent Mg(2+) efflux activity was studied with the fluorescent Mg(2+) indicator furaptra in the presence of various potential antagonists known to inhibit other transporters and channels. Among the compounds tested, KB-R7943, an inhibitor of Na(+)/Ca(2+) exchange, most potently inhibited the Na(+)/Mg(2+) exchange with half inhibitory concentrations (IC(50)) of 21 μM: (25°C) and 16 μM: (35°C). These IC(50) values were a factor of three to four lower than those of imipramine, a widely used inhibitor of Na(+)/Mg(2+) exchange. Apart from the inhibitory effect on Na(+)/Mg(2+) exchange, relatively high concentrations of KB-R7943 (100 μM: at 25°C and ≥20 μM: at 35°C), in combination with prolonged UV-illumination, caused cell shortening, probably because of the phototoxicity of the compound and the formation of rigor crossbridges. We conclude that KB-R7943 may be a useful tool to study cellular Mg(2+) homeostasis if care is taken to minimize its phototoxicity.
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Affiliation(s)
- Michiko Tashiro
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402 Japan
| | - Hana Inoue
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402 Japan
| | - Masato Konishi
- Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, 160-8402 Japan
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Gwanyanya A, Macianskiene R, Bito V, Sipido KR, Vereecke J, Mubagwa K. Inhibition of the calcium-activated chloride current in cardiac ventricular myocytes by N-(p-amylcinnamoyl)anthranilic acid (ACA). Biochem Biophys Res Commun 2010; 402:531-6. [PMID: 20971070 DOI: 10.1016/j.bbrc.2010.10.069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 10/17/2010] [Indexed: 12/01/2022]
Abstract
N-(p-amylcinnamoyl)anthranilic acid (ACA), a phospholipase A(2) (PLA(2)) inhibitor, is structurally-related to non-steroidal anti-inflammatory drugs (NSAIDs) of the fenamate group and may also modulate various ion channels. We used the whole-cell, patch-clamp technique at room temperature to investigate the effects of ACA on the Ca(2+)-activated chloride current (I(Cl(Ca))) and other chloride currents in isolated pig cardiac ventricular myocytes. ACA reversibly inhibited I(Cl(Ca)) in a concentration-dependent manner (IC(50)=4.2 μM, n(Hill)=1.1), without affecting the L-type Ca(2+) current. Unlike ACA, the non-selective PLA(2) inhibitor bromophenacyl bromide (BPB; 50 μM) had no effect on I(Cl(Ca)). In addition, the analgesic NSAID structurally-related to ACA, diclofenac (50 μM) also had no effect on I(Cl(Ca)), whereas the current in the same cells could be suppressed by chloride channel blockers flufenamic acid (FFA; 100 μM) or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS;100 μM). Besides I(Cl(Ca)), ACA (50 μM) also suppressed the cAMP-activated chloride current, but to a lesser extent. It is proposed that the inhibitory effects of ACA on I(Cl(Ca)) are PLA(2)-independent and that the drug may serve as a useful tool in understanding the nature and function of cardiac anion channels.
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Affiliation(s)
- Asfree Gwanyanya
- Division of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium
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42
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Macianskiene R, Gwanyanya A, Sipido KR, Vereecke J, Mubagwa K. Induction of a novel cation current in cardiac ventricular myocytes by flufenamic acid and related drugs. Br J Pharmacol 2010; 161:416-29. [PMID: 20735425 PMCID: PMC2989592 DOI: 10.1111/j.1476-5381.2010.00901.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/26/2010] [Accepted: 04/18/2010] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Interest in non-selective cation channels has increased recently following the discovery of transient receptor potential (TRP) proteins, which constitute many of these channels. EXPERIMENTAL APPROACH We used the whole-cell patch-clamp technique on isolated ventricular myocytes to investigate the effect of flufenamic acid (FFA) and related drugs on membrane ion currents. KEY RESULTS With voltage-dependent and other ion channels inhibited, cells that were exposed to FFA, N-(p-amylcinnamoyl)anthranilic acid (ACA), ONO-RS-082 or niflumic acid (NFA) responded with an increase in currents. The induced current reversed at +38 mV, was unaffected by lowering extracellular Cl(-) concentration or by the removal of extracellular Ca(2+) and Mg(2+), and its inward but not outward component was suppressed in Na(+)-free extracellular conditions. The current was suppressed by Gd(3+) but was resistant to 2-aminoethoxydiphenyl borate (2-APB) and to amiloride. It could not be induced by the structurally related non-fenamate anti-inflammatory drug diclofenac, nor by the phospholipase-A(2) inhibitors bromoenol lactone and bromophenacyl bromide. Muscarinic or alpha-adrenoceptor activation or application of diacylglycerol failed to induce or modulate the current. CONCLUSIONS AND IMPLICATIONS Flufenamic acid and related drugs activate a novel channel conductance, where Na(+) is likely to be the major charge carrier. The identity of the channel remains unclear, but it is unlikely to be due to Ca(2+)-activated (e.g. TRPM4/5), Mg(2+)-sensitive (e.g. TRPM7) or divalent cation-selective TRPs.
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Affiliation(s)
- R Macianskiene
- Division of Experimental Cardiac Surgery, Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium
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43
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Chen HC, Xie J, Zhang Z, Su LT, Yue L, Runnels LW. Blockade of TRPM7 channel activity and cell death by inhibitors of 5-lipoxygenase. PLoS One 2010; 5:e11161. [PMID: 20567598 PMCID: PMC2887440 DOI: 10.1371/journal.pone.0011161] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 05/11/2010] [Indexed: 01/24/2023] Open
Abstract
TRPM7 is a ubiquitous divalent-selective ion channel with its own kinase domain. Recent studies have shown that suppression of TRPM7 protein expression by RNA interference increases resistance to ischemia-induced neuronal cell death in vivo and in vitro, making the channel a potentially attractive pharmacological target for molecular intervention. Here, we report the identification of the 5-lipoxygenase inhibitors, NDGA, AA861, and MK886, as potent blockers of the TRPM7 channel. Using a cell-based assay, application of these compounds prevented cell rounding caused by overexpression of TRPM7 in HEK-293 cells, whereas inhibitors of 12-lipoxygenase and 15-lipoxygenase did not prevent the change in cell morphology. Application of the 5-lipoxygenase inhibitors blocked heterologously expressed TRPM7 whole-cell currents without affecting the protein's expression level or its cell surface concentration. All three inhibitors were also effective in blocking the native TRPM7 current in HEK-293 cells. However, two other 5-lipoxygenase specific inhibitors, 5,6-dehydro-arachidonic acid and zileuton, were ineffective in suppressing TRPM7 channel activity. Targeted knockdown of 5-lipoxygenase did not reduce TRPM7 whole-cell currents. In addition, application of 5-hydroperoxyeicosatetraenoic acid (5-HPETE), the product of 5-lipoxygenase, or 5-HPETE's downstream metabolites, leukotriene B4 and leukotriene D4, did not stimulate TRPM7 channel activity. These data suggested that NDGA, AA861, and MK886 reduced the TRPM7 channel activity independent of their effect on 5-lipoxygenase activity. Application of AA861 and NDGA reduced cell death for cells overexpressing TRPM7 cultured in low extracellular divalent cations. Moreover, treatment of HEK-293 cells with AA861 increased cell resistance to apoptotic stimuli to a level similar to that obtained for cells in which TRPM7 was knocked down by RNA interference. In conclusion, NDGA, AA861, and MK886 are potent blockers of the TRPM7 channel capable of attenuating TRPM7's function during cell stress, making them effective tools for the biophysical characterization and suppression of TRPM7 channel conductance in vivo.
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Affiliation(s)
- Hsiang-Chin Chen
- Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America
| | - Jia Xie
- Calhoun Cardiology Center and Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Zheng Zhang
- Calhoun Cardiology Center and Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Li-Ting Su
- Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America
| | - Lixia Yue
- Calhoun Cardiology Center and Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail: (LWR); (LY)
| | - Loren W. Runnels
- Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America
- * E-mail: (LWR); (LY)
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Quamme GA. Molecular identification of ancient and modern mammalian magnesium transporters. Am J Physiol Cell Physiol 2010; 298:C407-29. [DOI: 10.1152/ajpcell.00124.2009] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A large number of mammalian Mg2+ transporters have been hypothesized on the basis of physiological data, but few have been investigated at the molecular level. The recent identification of a number of novel proteins that mediate Mg2+ transport has enhanced our understanding of how Mg2+ is translocated across mammalian membranes. Some of these transporters have some similarity to those found in prokaryocytes and yeast cells. Human Mrs2, a mitochondrial Mg2+ channel, shares many of the properties of the bacterial CorA and yeast Alr1 proteins. The SLC41 family of mammalian Mg2+ transporters has a similarity with some regions of the bacterial MgtE transporters. The mammalian ancient conserved domain protein (ACDP) Mg2+ transporters are found in prokaryotes, suggesting an ancient origin. However, other newly identified mammalian transporters, including TRPM6/7, MagT, NIPA, MMgT, and HIP14 families, are not represented in prokaryotic genomes, suggesting more recent development. MagT, NIPA, MMgT, and HIP14 transporters were identified by differential gene expression using microarray analysis. These proteins, which are found in many different tissues and subcellular organelles, demonstrate a diversity of structural properties and biophysical functions. The mammalian Mg2+ transporters have no obvious amino acid similarities, indicating that there are many ways to transport Mg2+ across membranes. Most of these proteins transport a number of divalent cations across membranes. Only MagT1 and NIPA2 are selective for Mg2+. Many of the identified mammalian Mg2+ transporters are associated with a number of congenital disorders encompassing a wide range of tissues, including intestine, kidney, brain, nervous system, and skin. It is anticipated that future research will identify other novel Mg2+ transporters and reveal other diseases.
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Affiliation(s)
- Gary A. Quamme
- Vancouver Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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Mishra R, Rao V, Ta R, Shobeiri N, Hill CE. Mg2+- and MgATP-inhibited and Ca2+/calmodulin-sensitive TRPM7-like current in hepatoma and hepatocytes. Am J Physiol Gastrointest Liver Physiol 2009; 297:G687-94. [PMID: 19661151 DOI: 10.1152/ajpgi.90683.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although understood to be ubiquitously expressed, the functional identification and significance of Mg(2+)-inhibited, nonspecific cation currents has been established in only a few cell types. Here we identified an outwardly rectifying nonspecific cation current in quiescent rat hepatocytes and the proliferating and polarized rat hepatoma, WIF-B. Under whole cell recording conditions in which cells were bathed and dialyzed with Na-gluconate solutions, the latter Ca(2+) and Mg(2+) free, current reversed close to 0 mV, was time independent, and was greater than 10 times higher at +120 mV compared with -120 mV. Outward current at -120 mV developed slowly, from 17.7 +/- 10.3 pA/pF at patch rupture to 106.6 +/- 15.6 pA/pF at 12 min in WIF-B cells, and 4.9 +/- 2.7 to 20.6 +/- 5.6 pA/pF in rat hepatocytes. The nonspecific TRP channel inhibitor, 2-aminoethoxyphenylborate (2-APB), inhibited current (IC(50) = 72 +/- 13 microM) and caused apoptotic cell death in WIF-B cells. Rat hepatocyte survival was more resistant to 2-APB. Dialysis of WIF-B cells with physiological concentrations of Mg(2+) and Mg-ATP, but not ATP alone, inhibited current development, suggesting that Trpm7 rather than Trpm6 underlies this current. RT-PCR demonstrated that both Trpm6 and Trpm7 are expressed at similar levels in both cell types, suggesting that the functional differences noted are not transcript dependent. Intracellular Ca(2+) (IC(50) = 125 +/- 35 nM) also inhibited current development, and this could be partially relieved by the calmodulin and Ca(2+)/calmodulin-dependent kinase inhibitors W-7, staurosporine, KN-93, or calmodulin kinase II (CaMKII) inhibitory peptide. To summarize, our results show that in addition to their established Mg(2+) sensitivity, Trpm7-like channels are inhibited by cytosolic Ca(2+) in a CaMKII-dependent manner and may support hepatocellular survival during proliferation.
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Affiliation(s)
- Ravi Mishra
- Department of Biology and Medicine, Hotel Dieu Hospital and Queen's University, Kingston, Ontario, Canada
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Abed E, Labelle D, Martineau C, Loghin A, Moreau R. Expression of transient receptor potential (TRP) channels in human and murine osteoblast-like cells. Mol Membr Biol 2008; 26:146-58. [PMID: 19115145 DOI: 10.1080/09687680802612721] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The preservation of bone mass relies on adequate proliferation, differentiation, secretion of matrix proteins and rate of apoptosis of the bone-forming osteoblasts. Although growing body of evidence indicates that the transient receptor potential (TRP) channels play important roles in numerous cellular functions, limited information is available about the TRP channels in osteoblasts. Here, we inventoried the gene expression and addressed some roles of the TRP channels in various osteoblast-like cells. The transcripts of canonical TRP (TRPC) channels were revealed for TRPC1, TRPC3, TRPC4 and TRPC6 in human MG-63, SaOS and U2 OS osteoblasts while transcripts for TRPC2, TRPC4, TRPC6 and TRPC7 were observed in the murine MC3T3 osteoblasts. PCR products were shown for the melastatin-related TRP (TRPM) channels TRPM4, TRPM6, TRPM7 and TRPM8 in all cell lines. The TRPM1 was specifically expressed by murine MC3T3 cells while the TRPM3 transcripts were revealed solely in human osteoblast-like cells. Transcripts for TRPV2 and TRPV4 were shown in osteoblastic cells. By interfering RNA approaches, the TRPC1 channels in osteoblasts were shown to be responsible for the capacitative calcium entry (CCE) and for the stimulation of cell proliferation by platelet-derived growth factor. On the other hand, interfering RNA-mediated abrogation of the expression of TRPM7, known as calcium and magnesium channels, resulted in the reduction of both basal and growth factor-stimulated osteoblastic cell proliferation. Our results provide the first complete reference for the gene expression of TRP channels in osteoblasts and point to their importance in cell proliferation.
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Affiliation(s)
- Elie Abed
- Laboratoire du Métabolisme osseux, BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
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Rondón LJ, Groenestege WMT, Rayssiguier Y, Mazur A. Relationship between low magnesium status and TRPM6 expression in the kidney and large intestine. Am J Physiol Regul Integr Comp Physiol 2008; 294:R2001-7. [PMID: 18385471 DOI: 10.1152/ajpregu.00153.2007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The body maintains Mg(2+) homeostasis by renal and intestinal (re)absorption. However, the molecular mechanisms that mediate transepithelial Mg(2+) transport are largely unknown. Transient receptor potential melastatin 6 (TRPM6) was recently identified and shown to function in active epithelial Mg(2+) transport in intestine and kidney. To define the relationship between Mg(2+) status and TRPM6 expression, we used two models of hypomagnesemia: 1) C57BL/6J mice fed a mildly or severely Mg(2+)-deficient diet, and 2) mice selected for either low (MgL) or high (MgH) erythrocyte and plasma Mg(2+) status. In addition, the mice were subjected to a severely Mg(2+)-deficient diet. Our results show that C57BL/6J mice fed a severely Mg(2+)-deficient diet developed hypomagnesemia and hypomagnesuria and showed increased TRPM6 expression in kidney and intestine. When fed a Mg(2+)-adequate diet, MgL mice presented hypomagnesemia and hypermagnesuria, and lower kidney and intestinal TRPM6 expression, compared with MgH mice. A severely Mg(2+)-deficient diet led to hypomagnesemia and hypomagnesuria in both strains. Furthermore, this diet induced kidney TRPM6 expression in MgL mice, but not in MgH mice. In conclusion, as shown in C57BL/6J mice, dietary Mg(2+)-restriction results in increased Mg(2+) (re)absorption, which is correlated with increased TRPM6 expression. In MgL and MgH mice, the inherited Mg(2+) status is linked to different TRPM6 expression. The MgL and MgH mice respond differently to a low-Mg(2+) diet with regard to TRPM6 expression in the kidney, consistent with genetic factors contributing to the regulation of cellular Mg(2+) levels. Further studies of these mice strains could improve our understanding of the genetics of Mg(2+) homeostasis.
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Affiliation(s)
- Lusliany J Rondón
- Unité de Nutrition Humaine, Centre de Recherche en Nutrition Humaine d'Auvergne, Theix, 63122 St. Genès Champanelle, France
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Touyz RM. Transient receptor potential melastatin 6 and 7 channels, magnesium transport, and vascular biology: implications in hypertension. Am J Physiol Heart Circ Physiol 2008; 294:H1103-18. [PMID: 18192217 DOI: 10.1152/ajpheart.00903.2007] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Magnesium, an essential intracellular cation, is critically involved in many biochemical reactions involved in the regulation of vascular tone and integrity. Decreased magnesium concentration has been implicated in altered vascular reactivity, endothelial dysfunction, vascular inflammation, and structural remodeling, processes important in vascular changes and target organ damage associated with hypertension. Until recently, very little was known about mechanisms regulating cellular magnesium homeostasis, and processes controlling transmembrane magnesium transport had been demonstrated only at the functional level. Two cation channels of the transient receptor potential melastatin (TRPM) cation channel family have now been identified as magnesium transporters, TRPM6 and TRPM7. These unique proteins, termed chanzymes because they possess a channel and a kinase domain, are differentially expressed, with TRPM6 being found primarily in epithelial cells and TRPM7 occurring ubiquitously. Vascular TRPM7 is modulated by vasoactive agents, pressure, stretch, and osmotic changes and may be a novel mechanotransducer. In addition to its magnesium transporter function, TRPM7 has been implicated as a signaling kinase involved in vascular smooth muscle cell growth, apoptosis, adhesion, contraction, cytoskeletal organization, and migration, important processes involved in vascular remodeling associated with hypertension and other vascular diseases. Emerging evidence suggests that vascular TRPM7 function may be altered in hypertension. This review discusses the importance of magnesium in vascular biology and implications in hypertension and highlights the transport systems, particularly TRPM6 and TRPM7, which may play a role in the control of vascular magnesium homeostasis. Since the recent identification and characterization of Mg2+-selective transporters, there has been enormous interest in the field. However, there is still a paucity of information, and much research is needed to clarify the exact mechanisms of magnesium regulation in the cardiovascular system and the implications of aberrant transmembrane magnesium transport in the pathogenesis of hypertension and other vascular diseases.
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Affiliation(s)
- Rhian M Touyz
- Kidney Research Center, Ottawa Heallth Research Institute, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
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Reed G, Cefaratti C, Berti-Mattera LN, Romani A. Lack of insulin impairs Mg2+ homeostasis and transport in cardiac cells of streptozotocin-injected diabetic rats. J Cell Biochem 2008; 104:1034-53. [DOI: 10.1002/jcb.21690] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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50
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Abed E, Moreau R. Importance of melastatin-like transient receptor potential 7 and cations (magnesium, calcium) in human osteoblast-like cell proliferation. Cell Prolif 2007; 40:849-65. [PMID: 18021175 DOI: 10.1111/j.1365-2184.2007.00476.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Bone tissue in the adult is continuously being remodelled, and overall bone mass is maintained constant by the balance between osteoclastic bone resorption and osteoblastic bone formation. Adequate osteoblastic proliferation is essential for both appropriate formation and for regulation of resorption, and thereby the maintenance of bone remodelling equilibrium. OBJECTIVES Here, we have investigated the roles of melastatin-like transient receptor potential 6 and 7 (TRPM6, TRPM7), which are calcium (Ca2+) and magnesium (Mg2+) conducting channels, during proliferation of human osteoblasts. RESULTS Genetic expression of TRPM6 and TRPM7 was shown in human osteoblast-like MG-63, SaOS and U2-OS cells, and reduction of extracellular Mg2+ or Ca2+ led to a decrease of cell proliferation. Concomitant reduction of both ions further accentuated reduction of cell proliferation. Expression of TRPM7 channels was increased under conditions of reduced extracellular Mg2+ and Ca2+ levels whereas expression of TRPM6 was not modified, suggesting compensatory mechanisms afforded by TRPM7 in order to maintain intracellular ion homeostasis. Pre-incubation of cells in reduced extracellular Mg2+ conditions led to activation of Ca2+ and Mg2+ influx. Reduction of TRPM7 expression by specific siRNA prevented latter influx and inhibited cell proliferation. CONCLUSIONS Our results indicate that extracellular Mg2+ and Ca2+ deficiency reduces the proliferation of human osteoblastic cells. Expression and activity of TRPM7 is modulated by extracellular Mg2+ and Ca2+ availability, indicating that TRPM7 channels are involved in intracellular ion homeostasis and proliferation of osteoblasts.
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Affiliation(s)
- E Abed
- Laboratoire du Métabolisme Osseux, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
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