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Gest AMM, Lazzari-Dean JR, Ortiz G, Yaeger-Weiss SK, Boggess SC, Miller EW. A red-emitting carborhodamine for monitoring and measuring membrane potential. Proc Natl Acad Sci U S A 2024; 121:e2315264121. [PMID: 38551837 PMCID: PMC10998576 DOI: 10.1073/pnas.2315264121] [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: 10/06/2023] [Accepted: 01/25/2024] [Indexed: 04/02/2024] Open
Abstract
Biological membrane potentials, or voltages, are a central facet of cellular life. Optical methods to visualize cellular membrane voltages with fluorescent indicators are an attractive complement to traditional electrode-based approaches, since imaging methods can be high throughput, less invasive, and provide more spatial resolution than electrodes. Recently developed fluorescent indicators for voltage largely report changes in membrane voltage by monitoring voltage-dependent fluctuations in fluorescence intensity. However, it would be useful to be able to not only monitor changes but also measure values of membrane potentials. This study discloses a fluorescent indicator which can address both. We describe the synthesis of a sulfonated tetramethyl carborhodamine fluorophore. When this carborhodamine is conjugated with an electron-rich, methoxy (-OMe) containing phenylenevinylene molecular wire, the resulting molecule, CRhOMe, is a voltage-sensitive fluorophore with red/far-red fluorescence. Using CRhOMe, changes in cellular membrane potential can be read out using fluorescence intensity or lifetime. In fluorescence intensity mode, CRhOMe tracks fast-spiking neuronal action potentials (APs) with greater signal-to-noise than state-of-the-art BeRST 1 (another voltage-sensitive fluorophore). CRhOMe can also measure values of membrane potential. The fluorescence lifetime of CRhOMe follows a single exponential decay, substantially improving the quantification of membrane potential values using fluorescence lifetime imaging microscopy (FLIM). The combination of red-shifted excitation and emission, mono-exponential decay, and high voltage sensitivity enable fast FLIM recording of APs in cardiomyocytes. The ability to both monitor and measure membrane potentials with red light using CRhOMe makes it an important approach for studying biological voltages.
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Affiliation(s)
| | | | - Gloria Ortiz
- Department of Chemistry, University of California, Berkeley, CA 94720
| | | | - Steven C Boggess
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Evan W Miller
- Department of Chemistry, University of California, Berkeley, CA 94720
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720
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2
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Gest AM, Grenier V, Miller EW. Optical Estimation of Membrane Potential Values Using Fluorescence Lifetime Imaging Microscopy and Hybrid Chemical-Genetic Voltage Indicators. Bioelectricity 2024; 6:34-41. [PMID: 38516638 PMCID: PMC10951690 DOI: 10.1089/bioe.2023.0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024] Open
Abstract
Introduction Membrane potential (Vm), the voltage across a cell membrane, is an important biophysical phenomenon, central to the physiology of cells, tissues, and organisms. Voltage-sensitive fluorescent indicators are a powerful method for interrogating membrane potential in living systems, but most indicators are best suited for detecting changes in membrane potential rather than measuring values of the membrane potential. One promising approach is to use fluorescence lifetime imaging microscopy (FLIM) in combination of chemically synthesized dyes to estimate a value of membrane potential. However, a drawback is that chemically synthesized dyes show poor specificity of staining. Objectives To address this problem, we applied a chemical-genetic voltage imaging approach to FLIM to enable optical estimation of membrane potential values from genetically defined cells. Results In this report, we detail the characterization and evaluation of two of these systems in mammalian cells. We further validate the use of a FLIM-based chemical genetic voltage indicator in mammalian neurons. Conclusions Finally, we discuss opportunities for future improvements to chemical-genetic FLIM-based voltage indicators.
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Affiliation(s)
- Anneliese M.M. Gest
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Vincent Grenier
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Evan W. Miller
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Molecular & Cell Biology, University of California, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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3
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Gest AMM, Lazzari-Dean JR, Ortiz G, Yaeger-Weiss SK, Boggess SC, Miller EW. A red-emitting carborhodamine for monitoring and measuring membrane potential. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561080. [PMID: 37873283 PMCID: PMC10592620 DOI: 10.1101/2023.10.06.561080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Biological membrane potentials, or voltages, are a central facet of cellular life. Optical methods to visualize cellular membrane voltages with fluorescent indicators are an attractive complement to traditional electrode-based approaches, since imaging methods can be high throughput, less invasive, and provide more spatial resolution than electrodes. Recently developed fluorescent indicators for voltage largely report changes in membrane voltage by monitoring voltage-dependent fluctuations in fluorescence intensity. However, it would be useful to be able to not only monitor changes, but also measure values of membrane potentials. This study discloses a new fluorescent indicator which can address both. We describe the synthesis of a new sulfonated tetramethyl carborhodamine fluorophore. When this carborhodamine is conjugated with an electron-rich, methoxy (-OMe) containing phenylenevinylene molecular wire, the resulting molecule, CRhOMe, is a voltage-sensitive fluorophore with red/far-red fluorescence. Using CRhOMe, changes in cellular membrane potential can be read out using fluorescence intensity or lifetime. In fluorescence intensity mode, CRhOMe tracks fast-spiking neuronal action potentials with greater signal-to-noise than state-of-the-art BeRST (another voltage-sensitive fluorophore). CRhOMe can also measure values of membrane potential. The fluorescence lifetime of CRhOMe follows a single exponential decay, substantially improving the quantification of membrane potential values using fluorescence lifetime imaging microscopy (FLIM). The combination of red-shifted excitation and emission, mono-exponential decay, and high voltage sensitivity enable fast FLIM recording of action potentials in cardiomyocytes. The ability to both monitor and measure membrane potentials with red light using CRhOMe makes it an important approach for studying biological voltages.
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Affiliation(s)
| | | | - Gloria Ortiz
- Department of Chemistry, University of California, Berkeley
| | | | | | - Evan W Miller
- Department of Chemistry, University of California, Berkeley
- Department of Molecular & Cell Biology, University of California, Berkeley
- Helen Wills Neuroscience Institute, University of California, Berkeley
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4
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Yan J, Bading H. The Disruption of NMDAR/TRPM4 Death Signaling with TwinF Interface Inhibitors: A New Pharmacological Principle for Neuroprotection. Pharmaceuticals (Basel) 2023; 16:1085. [PMID: 37631001 PMCID: PMC10458786 DOI: 10.3390/ph16081085] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 07/24/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
With the discovery that the acquisition of toxic features by extrasynaptic NMDA receptors (NMDARs) involves their physical interaction with the non-selective cation channel, TRPM4, it has become possible to develop a new pharmacological principle for neuroprotection, namely the disruption of the NMDAR/TRPM4 death signaling complex. This can be accomplished through the expression of the TwinF domain, a 57-amino-acid-long stretch of TRPM4 that mediates its interaction with NMDARs, but also using small molecule TwinF interface (TI) inhibitors, also known as NMDAR/TRPM4 interaction interface inhibitors. Both TwinF and small molecule TI inhibitors detoxify extrasynaptic NMDARs without interfering with synaptic NMDARs, which serve important physiological functions in the brain. As the toxic signaling of extrasynaptic NMDARs contributes to a wide range of neurodegenerative conditions, TI inhibitors may offer therapeutic options for currently untreatable human neurodegenerative diseases including Amyotrophic Lateral Sclerosis, Alzheimer's disease, and Huntington's disease.
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Affiliation(s)
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, 69120 Heidelberg, Germany
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5
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TRPM4 Participates in Irradiation-Induced Aortic Valve Remodeling in Mice. Cancers (Basel) 2022; 14:cancers14184477. [PMID: 36139640 PMCID: PMC9497207 DOI: 10.3390/cancers14184477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Despite its benefit in cancer treatment, thoracic irradiation can induce aortic valve stenosis with fibrosis and calcification. The TRPM4 cation channel is known to participate in cellular remodeling including the transition of cardiac fibroblasts to myofibroblasts, similar to that observed during aortic valve stenosis. This study evaluates if TRPM4 is involved in irradiation-induced aortic valve damage. The aortic valve of mice was targeted by irradiation. Cardiac echography 5 months after treatment revealed an increase in aortic jet velocity, indicating stenosis. This was not observed in non-treated animals. Histological analysis revealed an increase in valvular cusp surface associated with fibrosis which was not observed in non-treated animals. The experiments were reproduced on mice after Trpm4 gene disruption. In these animals, irradiation did not induce valvular remodeling. It indicates that TRPM4 influences irradiation-induced aortic valve damage and thus could be a target to prevent such side effects of irradiation. Abstract Thoracic radiotherapy can lead to cardiac remodeling including valvular stenosis due to fibrosis and calcification. The monovalent non-selective cation channel TRPM4 is known to be involved in calcium handling and to participate in fibroblast transition to myofibroblasts, a phenomenon observed during aortic valve stenosis. The goal of this study was to evaluate if TRPM4 is involved in irradiation-induced aortic valve damage. Four-month-old Trpm4+/+ and Trpm4−/− mice received 10 Gy irradiation at the aortic valve. Cardiac parameters were evaluated by echography until 5 months post-irradiation, then hearts were collected for morphological and histological assessments. At the onset of the protocol, Trpm4+/+ and Trpm4−/− mice exhibited similar maximal aortic valve jet velocity and mean pressure gradient. Five months after irradiation, Trpm4+/+ mice exhibited a significant increase in those parameters, compared to the untreated animals while no variation was detected in Trpm4−/− mice. Morphological analysis revealed that irradiated Trpm4+/+ mice exhibited a 53% significant increase in the aortic valve cusp surface while no significant variation was observed in Trpm4−/− animals. Collagen staining revealed aortic valve fibrosis in irradiated Trpm4+/+ mice but not in irradiated Trpm4−/− animals. It indicates that TRPM4 influences irradiation-induced valvular remodeling.
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6
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A Novel Role of the TRPM4 Ion Channel in Exocytosis. Cells 2022; 11:cells11111793. [PMID: 35681487 PMCID: PMC9180413 DOI: 10.3390/cells11111793] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 11/23/2022] Open
Abstract
Under physiological conditions, the widely expressed calcium-activated TRPM4 channel conducts sodium into cells. This sodium influx depolarizes the plasma membrane and reduces the driving force for calcium entry. The aberrant expression or function of TRPM4 has been reported in various diseases, including different types of cancer. TRPM4 is mainly localized in the plasma membrane, but it is also found in intracellular vesicles, which can undergo exocytosis. In this study, we show that calcium-induced exocytosis in the colorectal cancer cell line HCT116 is dependent on TRPM4. In addition, the findings from some studies of prostate cancer cell lines suggest a more general role of TRPM4 in calcium-induced exocytosis in cancer cells. Furthermore, calcium-induced exocytosis depends on TRPM4 ion conductivity. Additionally, an increase in intracellular calcium results in the delivery of TRPM4 to the plasma membrane. This process also depends on TRPM4 ion conductivity. TRPM4-dependent exocytosis and the delivery of TRPM4 to the plasma membrane are mediated by SNARE proteins. Finally, we provide evidence that calcium-induced exocytosis depends on TRPM4 ion conductivity, not within the plasma membrane, but rather in TRPM4-containing vesicles.
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Borgström A, Peinelt C, Stokłosa P. TRPM4 in Cancer-A New Potential Drug Target. Biomolecules 2021; 11:biom11020229. [PMID: 33562811 PMCID: PMC7914809 DOI: 10.3390/biom11020229] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/11/2022] Open
Abstract
Transient receptor potential melastatin 4 (TRPM4) is widely expressed in various organs and associated with cardiovascular and immune diseases. Lately, the interest in studies on TRPM4 in cancer has increased. Thus far, TRPM4 has been investigated in diffuse large B-cell lymphoma, prostate, colorectal, liver, breast, urinary bladder, cervical, and endometrial cancer. In several types of cancer TRPM4 is overexpressed and contributes to cancer hallmark functions such as increased proliferation and migration and cell cycle shift. Hence, TRPM4 is a potential prognostic cancer marker and a promising anticancer drug target candidate. Currently, the underlying mechanism by which TRPM4 contributes to cancer hallmark functions is under investigation. TRPM4 is a Ca2+-activated monovalent cation channel, and its ion conductivity can decrease intracellular Ca2+ signaling. Furthermore, TRPM4 can interact with different partner proteins. However, the lack of potent and specific TRPM4 inhibitors has delayed the investigations of TRPM4. In this review, we summarize the potential mechanisms of action and discuss new small molecule TRPM4 inhibitors, as well as the TRPM4 antibody, M4P. Additionally, we provide an overview of TRPM4 in human cancer and discuss TRPM4 as a diagnostic marker and anticancer drug target.
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8
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Saminathan A, Devany J, Veetil AT, Suresh B, Pillai KS, Schwake M, Krishnan Y. A DNA-based voltmeter for organelles. NATURE NANOTECHNOLOGY 2021; 16:96-103. [PMID: 33139937 PMCID: PMC8513801 DOI: 10.1038/s41565-020-00784-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 09/21/2020] [Indexed: 05/16/2023]
Abstract
The role of membrane potential in most intracellular organelles remains unexplored because of the lack of suitable tools. Here, we describe Voltair, a fluorescent DNA nanodevice that reports the absolute membrane potential and can be targeted to organelles in live cells. Voltair consists of a voltage-sensitive fluorophore and a reference fluorophore for ratiometry, and acts as an endocytic tracer. Using Voltair, we could measure the membrane potential of different organelles in situ in live cells. Voltair can potentially guide the rational design of biocompatible electronics and enhance our understanding of how membrane potential regulates organelle biology.
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Affiliation(s)
- Anand Saminathan
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - John Devany
- Department of Physics, The University of Chicago, Chicago, IL, USA
| | - Aneesh Tazhe Veetil
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - Bhavyashree Suresh
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | | | - Michael Schwake
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Biochemistry III/Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, Bielefeld, Germany
| | - Yamuna Krishnan
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
- Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
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9
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Lavanderos B, Silva I, Cruz P, Orellana-Serradell O, Saldías MP, Cerda O. TRP Channels Regulation of Rho GTPases in Brain Context and Diseases. Front Cell Dev Biol 2020; 8:582975. [PMID: 33240883 PMCID: PMC7683514 DOI: 10.3389/fcell.2020.582975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
Neurological and neuropsychiatric disorders are mediated by several pathophysiological mechanisms, including developmental and degenerative abnormalities caused primarily by disturbances in cell migration, structural plasticity of the synapse, and blood-vessel barrier function. In this context, critical pathways involved in the pathogenesis of these diseases are related to structural, scaffolding, and enzymatic activity-bearing proteins, which participate in Ca2+- and Ras Homologs (Rho) GTPases-mediated signaling. Rho GTPases are GDP/GTP binding proteins that regulate the cytoskeletal structure, cellular protrusion, and migration. These proteins cycle between GTP-bound (active) and GDP-bound (inactive) states due to their intrinsic GTPase activity and their dynamic regulation by GEFs, GAPs, and GDIs. One of the most important upstream inputs that modulate Rho GTPases activity is Ca2+ signaling, positioning ion channels as pivotal molecular entities for Rho GTPases regulation. Multiple non-selective cationic channels belonging to the Transient Receptor Potential (TRP) family participate in cytoskeletal-dependent processes through Ca2+-mediated modulation of Rho GTPases. Moreover, these ion channels have a role in several neuropathological events such as neuronal cell death, brain tumor progression and strokes. Although Rho GTPases-dependent pathways have been extensively studied, how they converge with TRP channels in the development or progression of neuropathologies is poorly understood. Herein, we review recent evidence and insights that link TRP channels activity to downstream Rho GTPase signaling or modulation. Moreover, using the TRIP database, we establish associations between possible mediators of Rho GTPase signaling with TRP ion channels. As such, we propose mechanisms that might explain the TRP-dependent modulation of Rho GTPases as possible pathways participating in the emergence or maintenance of neuropathological conditions.
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Affiliation(s)
- Boris Lavanderos
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Ian Silva
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Pablo Cruz
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Octavio Orellana-Serradell
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - María Paz Saldías
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile
| | - Oscar Cerda
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Santiago, Chile.,The Wound Repair, Treatment and Health (WoRTH) Initiative, Santiago, Chile
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10
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Jerath G, Goyal R, Trivedi V, Santhoshkumar TR, Ramakrishnan V. Conformationally constrained peptides for drug delivery. J Pept Sci 2020; 26:e3244. [PMID: 32128940 DOI: 10.1002/psc.3244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 12/26/2022]
Abstract
Peptides have shown great potential in acting as template for developing versatile carrier platforms in nanomedicine, aimed at selective delivery of drugs to only pathological tissues saving its normal neighbors. Cell-penetrating peptides (CPPs) are short oligomeric peptides capable of translocating across the cell membrane while simultaneously employing multiple mechanisms of entry. Most CPPs exist as disordered structures in solution and may adopt a helical conformation on interaction with cell membrane, vital to their penetrative capability. Herein, we report a series of cationic helical amphipathic peptides (CHAPs), which are topologically constrained to be helical. The peptides were tested against cervical and breast cancer cells for their cell penetration and drug delivery potential. The cellular uptake of CHAP peptides is independent of temperature and energy availability. The activity of the peptides is biocompatible in bovine serum. CHAPs delivered functional methotrexate (MTX) inside the cell as CHAP-MTX conjugates. CHAP-MTX conjugates were more toxic to cancer cells than MTX alone. However, the CHAP-MTX conjugates were less toxic to HEK-293 cells compared with the cancer cells suggesting higher affinity towards cancer cells.
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Affiliation(s)
- Gaurav Jerath
- Molecular Informatics and Design Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - Ruchika Goyal
- Molecular Informatics and Design Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - Vishal Trivedi
- Malaria Research Group, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | | | - Vibin Ramakrishnan
- Molecular Informatics and Design Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
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11
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Li Z, Fisher C, Gardner I, Ghosh A, Litchfield J, Maurer TS. Modeling Exposure to Understand and Predict Kidney Injury. Semin Nephrol 2019; 39:176-189. [DOI: 10.1016/j.semnephrol.2018.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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12
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Alom F, Matsuyama H, Nagano H, Fujikawa S, Tanahashi Y, Unno T. Involvement of transient receptor potential melastatin 4 channels in the resting membrane potential setting and cholinergic contractile responses in mouse detrusor and ileal smooth muscles. J Vet Med Sci 2019; 81:217-228. [PMID: 30518701 PMCID: PMC6395210 DOI: 10.1292/jvms.18-0631] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Here, we investigated the effects of 9-hydroxyphenanthrene (9-phenanthrol), a potent and selective transient receptor potential melastatin 4 (TRPM4) channel blocker, on the resting membrane potential and cholinergic contractile responses to elucidate the functional role of TRPM4 channels in the contractile activities of mouse detrusor and ileal longitudinal smooth muscles. We observed that, 9-phenanthrol (3-30 µM) did not significantly inhibit high K+-induced contractions in both preparations; however, 9-phenanthrol (10 µM) strongly inhibited cholinergic contractions evoked by electrical field stimulation in detrusor preparations compared to inhibitions in ileal preparations. 9-Phenanthrol (10 µM) significantly inhibited the muscarinic agonist, carbachol-induced contractile responses and slowed the maximum upstroke velocities of the contraction in detrusor preparations. However, the agent (10 µM) did not inhibit the contractions due to intracellular Ca2+ release evoked by carbachol, suggesting that the inhibitory effect of 9-phenanthrol may primarily be due to the inhibition of the membrane depolarization process incurred by TRPM4 channels. On the other hand, 9-phenanthrol (10 µM) did not affect carbachol-induced contractile responses in ileal preparations. Further, 9-phenanthrol (10 µM) significantly hyperpolarized the resting membrane potential and decreased the basal tone in both detrusor and ileal muscle preparations. Taken together, our results suggest that TRPM4 channels are constitutively active and are involved in setting of the resting membrane potential, thereby regulating the basal tone in detrusor and ileal smooth muscles. Thus, TRPM4 channels play a significant role in cholinergic signaling in detrusor, but not ileal, smooth muscles.
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Affiliation(s)
- Firoj Alom
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hayato Matsuyama
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroshi Nagano
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Saki Fujikawa
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Yasuyuki Tanahashi
- Department of Animal Medical Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Toshihiro Unno
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.,Laboratory of Veterinary Pharmacology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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13
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Duret G, Polali S, Anderson ED, Bell AM, Tzouanas CN, Avants BW, Robinson JT. Magnetic Entropy as a Proposed Gating Mechanism for Magnetogenetic Ion Channels. Biophys J 2019; 116:454-468. [PMID: 30665695 PMCID: PMC6369444 DOI: 10.1016/j.bpj.2019.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 12/22/2018] [Accepted: 01/02/2019] [Indexed: 12/25/2022] Open
Abstract
Magnetically sensitive ion channels would allow researchers to better study how specific brain cells affect behavior in freely moving animals; however, recent reports of "magnetogenetic" ion channels based on biogenic ferritin nanoparticles have been questioned because known biophysical mechanisms cannot explain experimental observations. Here, we reproduce a weak magnetically mediated calcium response in HEK cells expressing a previously published TRPV4-ferritin fusion protein. We find that this magnetic sensitivity is attenuated when we reduce the temperature sensitivity of the channel but not when we reduce the mechanical sensitivity of the channel, suggesting that the magnetic sensitivity of this channel is thermally mediated. As a potential mechanism for this thermally mediated magnetic response, we propose that changes in the magnetic entropy of the ferritin particle can generate heat via the magnetocaloric effect and consequently gate the associated temperature-sensitive ion channel. Unlike other forms of magnetic heating, the magnetocaloric mechanism can cool magnetic particles during demagnetization. To test this prediction, we constructed a magnetogenetic channel based on the cold-sensitive TRPM8 channel. Our observation of a magnetic response in cold-gated channels is consistent with the magnetocaloric hypothesis. Together, these new data and our proposed mechanism of action provide additional resources for understanding how ion channels could be activated by low-frequency magnetic fields.
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Affiliation(s)
- Guillaume Duret
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas
| | - Sruthi Polali
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas; Applied Physics Program, Rice University, Houston, Texas
| | - Erin D Anderson
- Department of Bioengineering, Rice University, Houston, Texas
| | - A Martin Bell
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas; Applied Physics Program, Rice University, Houston, Texas
| | | | - Benjamin W Avants
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas
| | - Jacob T Robinson
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas; Department of Bioengineering, Rice University, Houston, Texas; Applied Physics Program, Rice University, Houston, Texas; Department of Neuroscience, Baylor College of Medicine, Houston, Texas.
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14
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Sagredo AI, Sagredo EA, Pola V, Echeverría C, Andaur R, Michea L, Stutzin A, Simon F, Marcelain K, Armisén R. TRPM4 channel is involved in regulating epithelial to mesenchymal transition, migration, and invasion of prostate cancer cell lines. J Cell Physiol 2018; 234:2037-2050. [PMID: 30343491 DOI: 10.1002/jcp.27371] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 08/17/2018] [Indexed: 12/17/2022]
Abstract
Transient Receptor Potential Melastatin 4 (TRPM4) is a Ca2+ -activated and voltage-dependent monovalent cation channel, which depolarizes the plasma cell membrane, thereby modulating Ca2+ influx across Ca2+ -permeable pathways. TRPM4 is involved in different physiological processes such as T cell activation and the migration of endothelial and certain immune cells. Overexpression of this channel has been reported in various types of tumors including prostate cancer. In this study, a significant overexpression of TRPM4 was found only in samples from cancer with a Gleason score higher than 7, which are more likely to spread. To evaluate whether TRPM4 overexpression was related to the spreading capability of tumors, TRPM4 was knockdown by using shRNAs in PC3 prostate cancer cells and the effect on cellular migration and invasion was analyzed. PC3 cells with reduced levels of TRPM4 (shTRPM4) display a decrease of the migration/invasion capability. A reduction in the expression of Snail1, a canonical epithelial to mesenchymal transition (EMT) transcription factor, was also observed. Consistently, these cells showed a significant change in the expression of key EMT markers such as MMP9, E-cadherin/N-cadherin, and vimentin, indicating a partial reversion of the EMT process. Whereas, the overexpression of TRPM4 in LnCaP cells resulted in increased levels of Snail1, reduction in the expression of E-cadherin and increase in their migration potential. This study suggests a new and indirect mechanism of regulation of migration/invasion process by TRPM4 in prostate cancer cells, by inducing the expression of Snail1 gene and consequently, increasing the EMT.
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Affiliation(s)
- Alfredo I Sagredo
- Facultad de Medicina, Centro de Investigación y Tratamiento del Cáncer, Universidad de Chile, Chile
| | - Eduardo A Sagredo
- Facultad de Medicina, Centro de Investigación y Tratamiento del Cáncer, Universidad de Chile, Chile
| | - Victor Pola
- Departamento de Oncología Básico-Clínica, Facultad de Medicina, Universidad de Chile, Chile
| | - César Echeverría
- Facultad de Medicina, Centro de Investigación y Tratamiento del Cáncer, Universidad de Chile, Chile.,Facultad de Medicina, Universidad de Atacama, Copiapo, Chile
| | - Rodrigo Andaur
- Departamento de Oncología Básico-Clínica, Facultad de Medicina, Universidad de Chile, Chile
| | - Luis Michea
- Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Andrés Stutzin
- Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Chile
| | - Felipe Simon
- Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Katherine Marcelain
- Facultad de Medicina, Centro de Investigación y Tratamiento del Cáncer, Universidad de Chile, Chile.,Departamento de Oncología Básico-Clínica, Facultad de Medicina, Universidad de Chile, Chile
| | - Ricardo Armisén
- Facultad de Medicina, Centro de Investigación y Tratamiento del Cáncer, Universidad de Chile, Chile.,Departamento de Oncología Básico-Clínica, Facultad de Medicina, Universidad de Chile, Chile
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15
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Zhelay T, Wieczerzak KB, Beesetty P, Alter GM, Matsushita M, Kozak JA. Depletion of plasma membrane-associated phosphoinositides mimics inhibition of TRPM7 channels by cytosolic Mg 2+, spermine, and pH. J Biol Chem 2018; 293:18151-18167. [PMID: 30305398 PMCID: PMC6254349 DOI: 10.1074/jbc.ra118.004066] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 10/04/2018] [Indexed: 12/20/2022] Open
Abstract
Transient receptor potential cation channel subfamily M member 7 (TRPM7) is an ion channel/protein kinase belonging to the TRP melastatin and eEF2 kinase families. Under physiological conditions, most native TRPM7 channels are inhibited by cytoplasmic Mg2+, protons, and polyamines. Currents through these channels (ITRPM7) are robustly potentiated when the cell interior is exchanged with low Mg2+-containing buffers. ITRPM7 is also potentiated by phosphatidyl inositol bisphosphate (PI(4,5)P2) and suppressed by its hydrolysis. Here we characterized internal Mg2+- and pH-mediated inhibition of TRPM7 channels in HEK293 cells overexpressing WT voltage-sensing phospholipid phosphatase (VSP) or its catalytically inactive variant VSP-C363S. VSP-mediated depletion of membrane phosphoinositides significantly increased channel sensitivity to Mg2+ and pH. Proton concentrations that were too low to inhibit ITRPM7 when the VSP-C363S variant was expressed (pH 8.2) became inhibitory in WT VSP-expressing cells. At pH 6.5, protons inhibited ITRPM7 both in WT and VSP C363S-expressing cells but with a faster time course in the WT VSP-expressing cells. Inhibition by 150 μm Mg2+ was also significantly faster in the WT VSP-expressing cells. Cellular PI(4,5)P2 depletion increased the sensitivity of TRPM7 channels to the inhibitor 2-aminoethyl diphenyl borinate, which acidifies the cytosol. Single substitutions at Ser-1107 of TRPM7, reducing its sensitivity to Mg2+, also decreased its inhibition by spermine and acidic pH. Furthermore, these channel variants were markedly less sensitive to VSP-mediated PI(4,5)P2 depletion than the WT. We conclude that the internal Mg2+-, polyamine-, and pH-mediated inhibition of TRPM7 channels is not direct but, rather, reflects electrostatic screening and resultant disruption of PI(4,5)P2-channel interactions.
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Affiliation(s)
- Tetyana Zhelay
- From the Departments of Neuroscience, Cell Biology, and Physiology and
| | | | - Pavani Beesetty
- From the Departments of Neuroscience, Cell Biology, and Physiology and
| | - Gerald M Alter
- Biochemistry and Molecular Biology, Wright State University, Dayton, Ohio 45435 and
| | - Masayuki Matsushita
- the Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan
| | - J Ashot Kozak
- From the Departments of Neuroscience, Cell Biology, and Physiology and.
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16
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Sagredo AI, Sagredo EA, Cappelli C, Báez P, Andaur RE, Blanco C, Tapia JC, Echeverría C, Cerda O, Stutzin A, Simon F, Marcelain K, Armisén R. TRPM4 regulates Akt/GSK3-β activity and enhances β-catenin signaling and cell proliferation in prostate cancer cells. Mol Oncol 2017; 12:151-165. [PMID: 28614631 PMCID: PMC5792731 DOI: 10.1002/1878-0261.12100] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 04/30/2017] [Accepted: 05/24/2017] [Indexed: 12/21/2022] Open
Abstract
Increased expression of the TRPM4 channel has been reported to be associated with the progression of prostate cancer. However, the molecular mechanism underlying its effect remains unknown. This work found that decreasing TRPM4 levels leads to the reduced proliferation of PC3 cells. This effect was associated with a decrease in total β‐catenin protein levels and its nuclear localization, and a significant reduction in Tcf/Lef transcriptional activity. Moreover, TRPM4 silencing increases the Ser33/Ser37/Thr41 β‐catenin phosphorylated population and reduces the phosphorylation of GSK‐3β at Ser9, suggesting an increase in β‐catenin degradation as the underlying mechanism. Conversely, TRPM4 overexpression in LNCaP cells increases the Ser9 inhibitory phosphorylation of GSK‐3β and the total levels of β‐catenin and its nonphosphorylated form. Finally, PC3 cells with reduced levels of TRPM4 showed a decrease in basal and stimulated phosphoactivation of Akt1, which is likely responsible for the decrease in GSK‐3β activity in these cells. Our results also suggest that the effect of TRPM4 on Akt1 is probably mediated by an alteration in the calcium/calmodulin‐EGFR axis, linking TRPM4 activity with the observed effects in β‐catenin‐related signaling pathways. These results suggest a role for TRPM4 channels in β‐catenin oncogene signaling and underlying mechanisms, highlighting this ion channel as a new potential target for future therapies in prostate cancer.
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Affiliation(s)
- Alfredo I Sagredo
- Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Eduardo A Sagredo
- Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Claudio Cappelli
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Pablo Báez
- Departamento de Oncologia Basico-Clinica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Rodrigo E Andaur
- Departamento de Oncologia Basico-Clinica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Constanza Blanco
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Julio C Tapia
- Departamento de Oncologia Basico-Clinica, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Cell Transformation Laboratory, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - César Echeverría
- Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo OHiggins, Santiago, Chile
| | - Oscar Cerda
- Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Andrés Stutzin
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Felipe Simon
- Laboratorio de Fisiopatologia Integrativa, Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas and Facultad de Medicina, Universidad Andres Bello, Santiago, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Katherine Marcelain
- Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Departamento de Oncologia Basico-Clinica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Ricardo Armisén
- Centro de Investigación y Tratamiento del Cáncer, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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17
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Provence A, Rovner ES, Petkov GV. Regulation of transient receptor potential melastatin 4 channel by sarcoplasmic reticulum inositol trisphosphate receptors: Role in human detrusor smooth muscle function. Channels (Austin) 2017. [PMID: 28644055 DOI: 10.1080/19336950.2017.1341023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We recently reported key physiologic roles for Ca2+-activated transient receptor potential melastatin 4 (TRPM4) channels in detrusor smooth muscle (DSM). However, the Ca2+-signaling mechanisms governing TRPM4 channel activity in human DSM cells are unexplored. As the TRPM4 channels are activated by Ca2+, inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release from the sarcoplasmic reticulum represents a potential Ca2+ source for TRPM4 channel activation. We used clinically-characterized human DSM tissues to investigate the molecular and functional interactions of the IP3Rs and TRPM4 channels. With in situ proximity ligation assay (PLA) and perforated patch-clamp electrophysiology, we tested the hypothesis that TRPM4 channels are tightly associated with the IP3Rs and are activated by IP3R-mediated Ca2+ release in human DSM. With in situ PLA, we demonstrated co-localization of the TRPM4 channels and IP3Rs in human DSM cells. As the TRPM4 channels and IP3Rs must be located within close apposition to functionally interact, these findings support the concept of a potential Ca2+-mediated TRPM4-IP3R regulatory mechanism. To investigate IP3R regulation of TRPM4 channel activity, we sought to determine the consequences of IP3R pharmacological inhibition on TRPM4 channel-mediated transient inward cation currents (TICCs). In freshly-isolated human DSM cells, blocking the IP3Rs with the selective IP3R inhibitor xestospongin-C significantly decreased TICCs. The data suggest that IP3Rs have a key role in mediating the Ca2+-dependent activation of TRPM4 channels in human DSM. The study provides novel insight into the molecular and cellular mechanisms regulating TRPM4 channels by revealing that TRPM4 channels and IP3Rs are spatially and functionally coupled in human DSM.
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Affiliation(s)
- Aaron Provence
- a Department of Drug Discovery and Biomedical Sciences , South Carolina College of Pharmacy, University of South Carolina , Columbia , SC , USA
| | - Eric S Rovner
- b Department of Urology , Medical University of South Carolina , Charleston , SC , USA
| | - Georgi V Petkov
- a Department of Drug Discovery and Biomedical Sciences , South Carolina College of Pharmacy, University of South Carolina , Columbia , SC , USA.,b Department of Urology , Medical University of South Carolina , Charleston , SC , USA.,c Department of Pharmaceutical Sciences , College of Pharmacy, University of Tennessee Health Science Center , Memphis , TN , USA
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18
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Hamilton KL. New life in overactive bladder. Focus on "Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function". Am J Physiol Cell Physiol 2016; 310:C597-9. [PMID: 26888821 DOI: 10.1152/ajpcell.00039.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Kirk L Hamilton
- Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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19
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Hristov KL, Smith AC, Parajuli SP, Malysz J, Rovner ES, Petkov GV. Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function. Am J Physiol Cell Physiol 2016; 310:C600-11. [PMID: 26791488 DOI: 10.1152/ajpcell.00270.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 01/13/2016] [Indexed: 11/22/2022]
Abstract
Transient receptor potential melastatin 4 (TRPM4) channels are Ca(2+)-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.
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Affiliation(s)
- Kiril L Hristov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Amy C Smith
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Shankar P Parajuli
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and
| | - Eric S Rovner
- Medical University of South Carolina, Charleston, South Carolina
| | - Georgi V Petkov
- Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina; and Medical University of South Carolina, Charleston, South Carolina
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20
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Flannery RJ, Kleene NK, Kleene SJ. A TRPM4-dependent current in murine renal primary cilia. Am J Physiol Renal Physiol 2015; 309:F697-707. [PMID: 26290373 PMCID: PMC4609916 DOI: 10.1152/ajprenal.00294.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 08/13/2015] [Indexed: 12/13/2022] Open
Abstract
Defects in primary cilia lead to a variety of human diseases. One of these, polycystic kidney disease, can be caused by defects in a Ca²⁺-gated ion channel (TRPP2) found on the cilium. Other ciliary functions also contribute to cystogenesis, and defects in apical Ca²⁺ homeostasis have been implicated. By recording directly from the native cilia of mIMCD-3 cells, a murine cell line of renal epithelial origin, we have identified a second Ca²⁺-gated channel in the ciliary membrane: the transient receptor potential cation channel, subfamily M, member 4 (TRPM4). In excised primary cilia, TRPM4 was found to have a low sensitivity to Ca²⁺, with an EC₅₀ of 646 μM at +100 mV. It was inhibited by MgATP and by 9-phenanthrol. The channel was not permeable to Ca²⁺ or Cl⁻ and had a permeability ratio PK/PNa of 1.42. Reducing the expression of Trpm4 mRNA with short hairpin (sh) RNA reduced the TRPM4 current by 87% and shortened primary cilia by 43%. When phospholipase C was inhibited, the sensitivity to cytoplasmic Ca²⁺ greatly increased (EC₅₀ = 26 μM at +100 mV), which is consistent with previous reports that phosphatidylinositol 4,5-bisphosphate (PIP2) modulates the channel. MgATP did not restore the channel to a preinactivation state, suggesting that the enzyme or substrate necessary for making PIP2 is not abundant in primary cilia of mIMCD-3 cells. The function of TRPM4 in renal primary cilia is not yet known, but it is likely to influence the apical Ca²⁺ dynamics of the cell, perhaps in tandem with TRPP2.
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Affiliation(s)
- Richard J Flannery
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio
| | - Nancy K Kleene
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio
| | - Steven J Kleene
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio
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21
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Homer proteins mediate the interaction between STIM1 and Cav1.2 channels. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1145-53. [PMID: 25712868 DOI: 10.1016/j.bbamcr.2015.02.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/28/2015] [Accepted: 02/16/2015] [Indexed: 11/23/2022]
Abstract
STIM1 is a ubiquitous Ca2+ sensor of the intracellular, agonist-sensitive, Ca2+ stores that communicates the filling state of the Ca2+ compartments to plasma membrane store-operated Ca2+ (SOC) channels. STIM1 has been presented as a point of convergence between store-operated and voltage-operated Ca2+ influx, both inducing activation of SOC channels while suppressing Cav1.2 channels. Here we report that Homer proteins play a relevant role in the communication between STIM1 and Cav1.2 channels. HEK-293 cells transiently expressing Cav1.2 channel subunits α1, β2 and α2δ-1 exhibited a significant Ca2+ entry upon treatment with a high concentration of KCl. In Cav1.2-expressing cells, treatment with thapsigargin (TG), to induce passive discharge of the intracellular Ca2+ stores, resulted in Ca2+ influx that was significantly greater than in cells not expressing Cav1.2 channels, a difference that was abolished by nifedipine and diltiazem. Treatment with TG induces co-immunoprecipitation of Homer1 with STIM1 and the Cav1.2 α1 subunit. Impairment of Homer function by introduction of the synthetic PPKKFR peptide into cells, which emulates the proline-rich sequences of the PPXXF motif, or using siRNA Homer1, reduced the association of STIM1 and the Cav1.2 α1 subunit. These findings indicate that Homer is important for the association between both proteins. Finally, treatment with siRNA Homer1 or the PPKKFR peptide enhanced the nifedipine-sensitive component of TG response in Cav1.2-expressing cells. Altogether, these findings provide evidence for a new role of Homer1 supporting the regulation of Cav1.2 channels by STIM1.
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22
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Moreau C, Kirchberger T, Swarbrick JM, Bartlett SJ, Fliegert R, Yorgan T, Bauche A, Harneit A, Guse AH, Potter BVL. Structure-activity relationship of adenosine 5'-diphosphoribose at the transient receptor potential melastatin 2 (TRPM2) channel: rational design of antagonists. J Med Chem 2013; 56:10079-102. [PMID: 24304219 PMCID: PMC3873810 DOI: 10.1021/jm401497a] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Adenosine
5′-diphosphoribose (ADPR) activates TRPM2, a Ca2+, Na+, and K+ permeable cation channel.
Activation is induced by ADPR binding to the cytosolic C-terminal
NudT9-homology domain. To generate the first structure–activity
relationship, systematically modified ADPR analogues were designed,
synthesized, and evaluated as antagonists using patch-clamp experiments
in HEK293 cells overexpressing human TRPM2. Compounds with a purine C8 substituent show antagonist activity, and an 8-phenyl
substitution (8-Ph-ADPR, 5) is very effective. Modification
of the terminal ribose results in a weak antagonist, whereas its removal
abolishes activity. An antagonist based upon a hybrid structure, 8-phenyl-2′-deoxy-ADPR
(86, IC50 = 3 μM), is more potent than
8-Ph-ADPR (5). Initial bioisosteric replacement of the
pyrophosphate linkage abolishes activity, but replacement of the pyrophosphate
and the terminal ribose by a sulfamate-based group leads to a weak
antagonist, a lead to more drug-like analogues. 8-Ph-ADPR (5) inhibits Ca2+ signalling and chemotaxis in human neutrophils,
illustrating the potential for pharmacological intervention at TRPM2.
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Affiliation(s)
- Christelle Moreau
- Wolfson Laboratory of Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom
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23
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Parajuli SP, Hristov KL, Sullivan MN, Xin W, Smith AC, Earley S, Malysz J, Petkov GV. Control of urinary bladder smooth muscle excitability by the TRPM4 channel modulator 9-phenanthrol. Channels (Austin) 2013; 7:537-40. [PMID: 24037125 DOI: 10.4161/chan.26289] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Ca (2+)-activated monovalent cation selective transient receptor potential melastatin 4 (TRPM4) channel has been recently identified in detrusor smooth muscle (DSM) of the urinary bladder. Two recent publications by our research group provide evidence in support of the novel hypothesis that TRPM4 channels enhance DSM excitability and contractility. This is a critical question as prior studies have primarily targeted hyperpolarizing currents facilitated by K(+) channels, but the depolarizing component in DSM cells is not well understood. For the first time, we utilized the selective TRPM4 channel inhibitor, 9-phenanthrol, to investigate TRPM4 channel functional effects in DSM at both cellular and tissue levels in rodents. Our new data presented here showed that in rat DSM cells, 9-phenanthrol attenuates spontaneous inward currents in the presence of the muscarinic receptor agonist, carbachol, thus reducing DSM cell excitability. In support of our original hypothesis, we found that TRPM4 channel mRNA levels are much higher in DSM vs. vascular smooth muscle and that inhibition of TRPM4 channels can potentially attenuate DSM excitability. Thus, we postulate the novel concept that selective pharmacological inhibition of TRPM4 channels can limit both excitability and contractility of DSM.
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Affiliation(s)
- Shankar P Parajuli
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Kiril L Hristov
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Michelle N Sullivan
- Vascular Physiology Research Group; Department of Biomedical Sciences; Colorado State University; Fort Collins, CO USA
| | - Wenkuan Xin
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Amy C Smith
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Scott Earley
- Vascular Physiology Research Group; Department of Biomedical Sciences; Colorado State University; Fort Collins, CO USA
| | - John Malysz
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
| | - Georgi V Petkov
- Department of Drug Discovery and Biomedical Sciences; South Carolina College of Pharmacy; University of South Carolina; Columbia, SC USA
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24
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Smith AC, Hristov KL, Cheng Q, Xin W, Parajuli SP, Earley S, Malysz J, Petkov GV. Novel role for the transient potential receptor melastatin 4 channel in guinea pig detrusor smooth muscle physiology. Am J Physiol Cell Physiol 2013; 304:C467-77. [PMID: 23302778 DOI: 10.1152/ajpcell.00169.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Members of the transient receptor potential (TRP) channel superfamily, including the Ca(2+)-activated monovalent cation-selective TRP melastatin 4 (TRPM4) channel, have been recently identified in the urinary bladder. However, their expression and function at the level of detrusor smooth muscle (DSM) remain largely unexplored. In this study, for the first time we investigated the role of TRPM4 channels in guinea pig DSM excitation-contraction coupling using a multidisciplinary approach encompassing protein detection, electrophysiology, live-cell Ca(2+) imaging, DSM contractility, and 9-phenanthrol, a recently characterized selective inhibitor of the TRPM4 channel. Western blot and immunocytochemistry experiments demonstrated the expression of the TRPM4 channel in whole DSM tissue and freshly isolated DSM cells with specific localization on the plasma membrane. Perforated whole cell patch-clamp recordings and real-time Ca(2+) imaging experiments with fura 2-AM, both using freshly isolated DSM cells, revealed that 9-phenanthrol (30 μM) significantly reduced the cation current and decreased intracellular Ca(2+) levels. 9-Phenanthrol (0.1-30 μM) significantly inhibited spontaneous, 0.1 μM carbachol-induced, 20 mM KCl-induced, and nerve-evoked contractions in guinea pig DSM-isolated strips with IC50 values of 1-7 μM and 70-80% maximum inhibition. 9-Phenanthrol also reduced nerve-evoked contraction amplitude induced by continuous repetitive electrical field stimulation of 10-Hz frequency and shifted the frequency-response curve (0.5-50 Hz) relative to the control. Collectively, our data demonstrate the novel finding that TRPM4 channels are expressed in guinea pig DSM and reveal their critical role in the regulation of guinea pig DSM excitation-contraction coupling.
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Affiliation(s)
- Amy C Smith
- Department of Pharmaceutical and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC 29208, USA
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Guinamard R, Sallé L, Simard C. The non-selective monovalent cationic channels TRPM4 and TRPM5. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:147-71. [PMID: 21290294 DOI: 10.1007/978-94-007-0265-3_8] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Transient Receptor Potential (TRP) proteins are non-selective cationic channels with a consistent Ca(2+)-permeability, except for TRPM4 and TRPM5 that are not permeable to this ion. However, Ca(2+) is a major regulator of their activity since both channels are activated by a rise in internal Ca(2+). Thus TRPM4 and TRPM5 are responsible for most of the Ca(2+)-activated non-selective cationic currents (NSC(Ca)) recorded in a large variety of tissues. Their activation induces cell-membrane depolarization that modifies the driving force for ions as well as activity of voltage gated channels and thereby strongly impacts cell physiology. In the last few years, the ubiquitously expressed TRPM4 channel has been implicated in insulin secretion, the immune response, constriction of cerebral arteries, the activity of inspiratory neurons and cardiac dysfunction. Conversely, TRPM5 whose expression is more restricted, has until now been mainly implicated in taste transduction.
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Affiliation(s)
- Romain Guinamard
- Groupe Cœur et Ischémie, EA 3212, Université de Caen, Sciences D, F-14032, Caen Cedex, France,
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Guinamard R, Demion M, Launay P. Physiological roles of the TRPM4 channel extracted from background currents. Physiology (Bethesda) 2010; 25:155-64. [PMID: 20551229 DOI: 10.1152/physiol.00004.2010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Calcium-activated nonselective cationic currents have been known for 30 years, but their physiological implications have remained unresolved until the recent cloning of the TRPM4 ion channel. Since then, TRPM4 has been identified as a key modulator of numerous calcium-dependent mechanisms such as the immune response, insulin secretion, cerebral artery constriction, respiratory rhythm, and cardiac conduction.
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Liu H, El Zein L, Kruse M, Guinamard R, Beckmann A, Bozio A, Kurtbay G, Mégarbané A, Ohmert I, Blaysat G, Villain E, Pongs O, Bouvagnet P. Gain-of-Function Mutations in
TRPM4
Cause Autosomal Dominant Isolated Cardiac Conduction Disease. ACTA ACUST UNITED AC 2010; 3:374-85. [DOI: 10.1161/circgenetics.109.930867] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Isolated cardiac conduction block is a relatively common condition in young and elderly populations. Genetic predisposing factors have long been suspected because of numerous familial case reports. Deciphering genetic predisposing factors of conduction blocks may give a hint at stratifying conduction block carriers in a more efficient way.
Methods and Results—
One Lebanese family and 2 French families with autosomal dominant isolated cardiac conduction blocks were used for linkage analysis. A maximum combined multipoint lod score of 10.5 was obtained on a genomic interval including more than 300 genes. After screening 12 genes of this interval for mutation, we found a heterozygous missense mutation of the
TRPM4
gene in each family (p.Arg164Trp, p.Ala432Thr, and p.Gly844Asp). This gene encodes the TRPM4 channel, a calcium-activated nonselective cation channel of the transient receptor potential melastatin (TRPM) ion channel family. All 3 mutations result in an increased current density. This gain of function is due to an elevated TRPM4 channel density at the cell surface secondary to impaired endocytosis and deregulation of Small Ubiquitin MOdifier conjugation (SUMOylation). Furthermore, we showed by immunohistochemistry that TRPM4 channel signal level is higher in atrial cardiomyocytes than in common ventricular cells, but is highest in Purkinje fibers. Small bundles of highly TRPM4-positive cells were found in the subendocardium and in rare intramural bundles.
Conclusions—
the
TRPM4
gene is a causative gene in isolated cardiac conduction disease with mutations resulting in a gain of function and TRPM4 channel being highly expressed in cardiac Purkinje fibers.
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Affiliation(s)
- Hui Liu
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Loubna El Zein
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Martin Kruse
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Romain Guinamard
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Alf Beckmann
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - André Bozio
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Güven Kurtbay
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - André Mégarbané
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Iris Ohmert
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Gérard Blaysat
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Elisabeth Villain
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Olaf Pongs
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
| | - Patrice Bouvagnet
- From Université de Lyon (H.L., L.E.Z., P.B.), Laboratoire Cardiogénétique, Equipe d'Accueil 4171, Lyon, France; Hospices Civils de Lyon (H.L., L.E.Z., P.B.), Groupe Hospitalier Est, Laboratoire Cardiogénétique, Bron, France; Institut für Neurale Signalverarbeitung (M.K., A.B., G.K., I.O., O.P.), Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany; Université de Caen (R.G.), Laboratoire d'Anesthésiologie Expérimentale et Physiologie Cellulaire, Equipe d'Accueil 3212, Caen,
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Kruse M, Schulze-Bahr E, Corfield V, Beckmann A, Stallmeyer B, Kurtbay G, Ohmert I, Schulze-Bahr E, Brink P, Pongs O. Impaired endocytosis of the ion channel TRPM4 is associated with human progressive familial heart block type I. J Clin Invest 2009; 119:2737-44. [PMID: 19726882 DOI: 10.1172/jci38292] [Citation(s) in RCA: 234] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 06/10/2009] [Indexed: 01/20/2023] Open
Abstract
Progressive familial heart block type I (PFHBI) is a progressive cardiac bundle branch disease in the His-Purkinje system that exhibits autosomal-dominant inheritance. In 3 branches of a large South African Afrikaner pedigree with an autosomal-dominant form of PFHBI, we identified the mutation c.19G-->A in the transient receptor potential cation channel, subfamily M, member 4 gene (TRPM4) at chromosomal locus 19q13.3. This mutation predicted the amino acid substitution p.E7K in the TRPM4 amino terminus. TRPM4 encodes a Ca2+-activated nonselective cation (CAN) channel that belongs to the transient receptor potential melastatin ion channel family. Quantitative analysis of TRPM4 mRNA content in human cardiac tissue showed the highest expression level in Purkinje fibers. Cellular expression studies showed that the c.19G-->A missense mutation attenuated deSUMOylation of the TRPM4 channel. The resulting constitutive SUMOylation of the mutant TRPM4 channel impaired endocytosis and led to elevated TRPM4 channel density at the cell surface. Our data therefore revealed a gain-of-function mechanism underlying this type of familial heart block.
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Affiliation(s)
- Martin Kruse
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany
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29
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Saleem F, Rowe ICM, Shipston MJ. Characterization of BK channel splice variants using membrane potential dyes. Br J Pharmacol 2008; 156:143-52. [PMID: 19068078 DOI: 10.1111/j.1476-5381.2008.00011.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Large conductance calcium- and voltage-activated potassium (BK) channels are encoded by a single gene that displays extensive pre-mRNA splicing. Here we exploited a membrane potential assay to investigate the sensitivity of different BK splice variants to elevations in intracellular free calcium and their inhibition by the BK channel blocker paxilline. EXPERIMENTAL APPROACH Murine BK channel splice variants were expressed in human embryonic kidney 293 cells and their properties analysed in response to ionomycin-induced calcium influx in both fluorescent membrane potential (fluorescent-imaging plate reader) and patch clamp electrophysiological assays. The dose-dependent inhibition of distinct splice variants by the BK channel-specific blocker paxilline was also investigated. KEY RESULTS Ionomycin-induced calcium influx induced a robust hyperpolarization of human embryonic kidney 293 cells expressing distinct BK channel splice variants: stress regulated exon (STREX), e22 and ZERO. Splice variant expression resulted in membrane hyperpolarization that displayed a rank order of potency in response to calcium influx of STREX > e22 > ZERO. The BK channel inhibitor paxilline exhibited very similar potency on all three splice variants with IC(50)s in membrane potential assays of 0.35 +/- 0.04, 0.37 +/- 0.03 and 0.70 +/- 0.02 micromol x L(-1) for STREX, ZERO and e22 respectively. CONCLUSIONS AND IMPLICATIONS BK channel splice variants can be rapidly discriminated using membrane potential based assays, based on their sensitivity to calcium. BK channel splice variants are inhibited by the specific blocker paxilline with similar IC(50)s. Thus, paxilline may be used in functional assays to inhibit BK channel function, irrespective of the variant expressed.
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Affiliation(s)
- F Saleem
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK
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Park JY, Hwang EM, Yarishkin O, Seo JH, Kim E, Yoo J, Yi GS, Kim DG, Park N, Ha CM, La JH, Kang D, Han J, Oh U, Hong SG. TRPM4b channel suppresses store-operated Ca2+ entry by a novel protein-protein interaction with the TRPC3 channel. Biochem Biophys Res Commun 2008; 368:677-83. [PMID: 18262493 DOI: 10.1016/j.bbrc.2008.01.153] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Accepted: 01/26/2008] [Indexed: 11/18/2022]
Abstract
We identified human TRPC3 protein by yeast two-hybrid screening of a human brain cDNA library with human TRPM4b as a bait. Immunoprecipitation and confocal microscopic analyses confirmed the protein-protein interaction between TRPM4b and TRPC3, and these two TRPs were found to be highly colocalized at the plasma membrane of HEK293T cells. Overexpression of TRPM4b suppressed TRPC3-mediated whole cell currents by more than 90% compared to those in TRPC3-expressed HEK293T cells. Furthermore, HEK293T cells stably overexpressing red fluorescent protein (RFP)-TRPM4b exhibited an almost complete abolition of UTP-induced store-operated Ca(2+) entry, which is known to take place via endogenous TRPC channels in HEK293T cells. This study is believed to provide the first clear evidence that TRPM4b interacts physically with TRPC3, a member of a different TRP subfamily, and regulates negatively the channel activity, in turn suppressing store-operated Ca(2+) entry through the TRPC3 channel.
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Affiliation(s)
- Jae-Yong Park
- Department of Physiology, Institute of Health Science, and Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju 660-751, Republic of Korea
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