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Chin M, Kaeser PS. The intracellular C-terminus confers compartment-specific targeting of voltage-gated calcium channels. Cell Rep 2024; 43:114428. [PMID: 38996073 DOI: 10.1016/j.celrep.2024.114428] [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: 12/28/2023] [Revised: 06/07/2024] [Accepted: 06/18/2024] [Indexed: 07/14/2024] Open
Abstract
To achieve the functional polarization that underlies brain computation, neurons sort protein material into distinct compartments. Ion channel composition, for example, differs between axons and dendrites, but the molecular determinants for their polarized trafficking remain obscure. Here, we identify mechanisms that target voltage-gated Ca2+ channels (CaVs) to distinct subcellular compartments. In hippocampal neurons, CaV2s trigger neurotransmitter release at the presynaptic active zone, and CaV1s localize somatodendritically. After knockout of all three CaV2s, expression of CaV2.1, but not CaV1.3, restores neurotransmitter release. We find that chimeric CaV1.3s with CaV2.1 intracellular C-termini localize to the active zone, mediate synaptic vesicle exocytosis, and render release sensitive to CaV1 blockers. This dominant targeting function of the CaV2.1 C-terminus requires the first EF hand in its proximal segment, and replacement of the CaV2.1 C-terminus with that of CaV1.3 abolishes CaV2.1 active zone localization and function. We conclude that CaV intracellular C-termini mediate compartment-specific targeting.
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Affiliation(s)
- Morven Chin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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2
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Chin M, Kaeser PS. The intracellular C-terminus confers compartment-specific targeting of voltage-gated Ca 2+ channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.23.573183. [PMID: 38187530 PMCID: PMC10769351 DOI: 10.1101/2023.12.23.573183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
To achieve the functional polarization that underlies brain computation, neurons sort protein material into distinct compartments. Ion channel composition, for example, differs between axons and dendrites, but the molecular determinants for their polarized trafficking remain obscure. Here, we identify the mechanisms that target voltage-gated Ca2+ channels (CaVs) to distinct subcellular compartments. In hippocampal neurons, CaV2s trigger neurotransmitter release at the presynaptic active zone, and CaV1s localize somatodendritically. After knockout of all three CaV2s, expression of CaV2.1, but not of CaV1.3, restores neurotransmitter release. Chimeric CaV1.3 channels with CaV2.1 intracellular C-termini localize to the active zone, mediate synaptic vesicle exocytosis, and render release fully sensitive to blockade of CaV1 channels. This dominant targeting function of the CaV2.1 C-terminus requires an EF hand in its proximal segment, and replacement of the CaV2.1 C-terminus with that of CaV1.3 abolishes CaV2.1 active zone localization. We conclude that the intracellular C-termini mediate compartment-specific CaV targeting.
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Affiliation(s)
- Morven Chin
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Pascal S. Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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3
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Li P, Qin D, Chen T, Hou W, Song X, Yin S, Song M, Fernando WCHA, Chen X, Sun Y, Wang J. Dysregulated Rbfox2 produces aberrant splicing of Ca V1.2 calcium channel in diabetes-induced cardiac hypertrophy. Cardiovasc Diabetol 2023; 22:168. [PMID: 37415128 PMCID: PMC10324275 DOI: 10.1186/s12933-023-01894-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 06/19/2023] [Indexed: 07/08/2023] Open
Abstract
BACKGROUND L-type Ca2+ channel CaV1.2 is essential for cardiomyocyte excitation, contraction and gene transcription in the heart, and abnormal functions of cardiac CaV1.2 channels are presented in diabetic cardiomyopathy. However, the underlying mechanisms are largely unclear. The functions of CaV1.2 channels are subtly modulated by splicing factor-mediated alternative splicing (AS), but whether and how CaV1.2 channels are alternatively spliced in diabetic heart remains unknown. METHODS Diabetic rat models were established by using high-fat diet in combination with low dose streptozotocin. Cardiac function and morphology were assessed by echocardiography and HE staining, respectively. Isolated neonatal rat ventricular myocytes (NRVMs) were used as a cell-based model. Cardiac CaV1.2 channel functions were measured by whole-cell patch clamp, and intracellular Ca2+ concentration was monitored by using Fluo-4 AM. RESULTS We find that diabetic rats develop diastolic dysfunction and cardiac hypertrophy accompanied by an increased CaV1.2 channel with alternative exon 9* (CaV1.2E9*), but unchanged that with alternative exon 8/8a or exon 33. The splicing factor Rbfox2 expression is also increased in diabetic heart, presumably because of dominate-negative (DN) isoform. Unexpectedly, high glucose cannot induce the aberrant expressions of CaV1.2 exon 9* and Rbfox2. But glycated serum (GS), the mimic of advanced glycation end-products (AGEs), upregulates CaV1.2E9* channels proportion and downregulates Rbfox2 expression in NRVMs. By whole-cell patch clamp, we find GS application hyperpolarizes the current-voltage curve and window currents of cardiac CaV1.2 channels. Moreover, GS treatment raises K+-triggered intracellular Ca2+ concentration ([Ca2+]i), enlarges cell surface area of NRVMs and induces hypertrophic genes transcription. Consistently, siRNA-mediated knockdown of Rbfox2 in NRVMs upregulates CaV1.2E9* channel, shifts CaV1.2 window currents to hyperpolarization, increases [Ca2+]i and induces cardiomyocyte hypertrophy. CONCLUSIONS AGEs, not glucose, dysregulates Rbfox2 which thereby increases CaV1.2E9* channels and hyperpolarizes channel window currents. These make the channels open at greater negative potentials and lead to increased [Ca2+]i in cardiomyocytes, and finally induce cardiomyocyte hypertrophy in diabetes. Our work elucidates the underlying mechanisms for CaV1.2 channel regulation in diabetic heart, and targeting Rbfox2 to reset the aberrantly spliced CaV1.2 channel might be a promising therapeutic approach in diabetes-induced cardiac hypertrophy.
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Affiliation(s)
- Pengpeng Li
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Dongxia Qin
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Tiange Chen
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Wei Hou
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Xinyu Song
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Shumin Yin
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Miaomiao Song
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - W C Hewith A Fernando
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Xiaojie Chen
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Yu Sun
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China.
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China.
| | - Juejin Wang
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211166, China.
- Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, 211166, China.
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4
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Chen Z, Mondal A, Abderemane-Ali F, Jang S, Niranjan S, Montaño JL, Zaro BW, Minor DL. EMC chaperone-Ca V structure reveals an ion channel assembly intermediate. Nature 2023; 619:410-419. [PMID: 37196677 PMCID: PMC10896479 DOI: 10.1038/s41586-023-06175-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/05/2023] [Indexed: 05/19/2023]
Abstract
Voltage-gated ion channels (VGICs) comprise multiple structural units, the assembly of which is required for function1,2. Structural understanding of how VGIC subunits assemble and whether chaperone proteins are required is lacking. High-voltage-activated calcium channels (CaVs)3,4 are paradigmatic multisubunit VGICs whose function and trafficking are powerfully shaped by interactions between pore-forming CaV1 or CaV2 CaVα1 (ref. 3), and the auxiliary CaVβ5 and CaVα2δ subunits6,7. Here we present cryo-electron microscopy structures of human brain and cardiac CaV1.2 bound with CaVβ3 to a chaperone-the endoplasmic reticulum membrane protein complex (EMC)8,9-and of the assembled CaV1.2-CaVβ3-CaVα2δ-1 channel. These structures provide a view of an EMC-client complex and define EMC sites-the transmembrane (TM) and cytoplasmic (Cyto) docks; interaction between these sites and the client channel causes partial extraction of a pore subunit and splays open the CaVα2δ-interaction site. The structures identify the CaVα2δ-binding site for gabapentinoid anti-pain and anti-anxiety drugs6, show that EMC and CaVα2δ interactions with the channel are mutually exclusive, and indicate that EMC-to-CaVα2δ hand-off involves a divalent ion-dependent step and CaV1.2 element ordering. Disruption of the EMC-CaV complex compromises CaV function, suggesting that the EMC functions as a channel holdase that facilitates channel assembly. Together, the structures reveal a CaV assembly intermediate and EMC client-binding sites that could have wide-ranging implications for the biogenesis of VGICs and other membrane proteins.
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Affiliation(s)
- Zhou Chen
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Abhisek Mondal
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Seil Jang
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Sangeeta Niranjan
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - José L Montaño
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Balyn W Zaro
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA, USA.
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, USA.
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
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5
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Morgenstern TJ, Nirwan N, Hernández-Ochoa EO, Bibollet H, Choudhury P, Laloudakis YD, Ben Johny M, Bannister RA, Schneider MF, Minor DL, Colecraft HM. Selective posttranslational inhibition of Ca Vβ 1-associated voltage-dependent calcium channels with a functionalized nanobody. Nat Commun 2022; 13:7556. [PMID: 36494348 PMCID: PMC9734117 DOI: 10.1038/s41467-022-35025-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
Ca2+ influx through high-voltage-activated calcium channels (HVACCs) controls diverse cellular functions. A critical feature enabling a singular signal, Ca2+ influx, to mediate disparate functions is diversity of HVACC pore-forming α1 and auxiliary CaVβ1-CaVβ4 subunits. Selective CaVα1 blockers have enabled deciphering their unique physiological roles. By contrast, the capacity to post-translationally inhibit HVACCs based on CaVβ isoform is non-existent. Conventional gene knockout/shRNA approaches do not adequately address this deficit owing to subunit reshuffling and partially overlapping functions of CaVβ isoforms. Here, we identify a nanobody (nb.E8) that selectively binds CaVβ1 SH3 domain and inhibits CaVβ1-associated HVACCs by reducing channel surface density, decreasing open probability, and speeding inactivation. Functionalizing nb.E8 with Nedd4L HECT domain yielded Chisel-1 which eliminated current through CaVβ1-reconstituted CaV1/CaV2 and native CaV1.1 channels in skeletal muscle, strongly suppressed depolarization-evoked Ca2+ influx and excitation-transcription coupling in hippocampal neurons, but was inert against CaVβ2-associated CaV1.2 in cardiomyocytes. The results introduce an original method for probing distinctive functions of ion channel auxiliary subunit isoforms, reveal additional dimensions of CaVβ1 signaling in neurons, and describe a genetically-encoded HVACC inhibitor with unique properties.
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Affiliation(s)
- Travis J. Morgenstern
- grid.239585.00000 0001 2285 2675Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY USA
| | - Neha Nirwan
- grid.266102.10000 0001 2297 6811Cardiovascular Research Institute, University of California, San Francisco, CA USA
| | - Erick O. Hernández-Ochoa
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Hugo Bibollet
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Papiya Choudhury
- grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
| | - Yianni D. Laloudakis
- grid.239585.00000 0001 2285 2675Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY USA
| | - Manu Ben Johny
- grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
| | - Roger A. Bannister
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA ,grid.411024.20000 0001 2175 4264Department of Pathology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Martin F. Schneider
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Daniel L. Minor
- grid.266102.10000 0001 2297 6811Cardiovascular Research Institute, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Department of Biochemistry and Biophysics, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA USA ,grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Henry M. Colecraft
- grid.239585.00000 0001 2285 2675Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY USA ,grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
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6
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El Ghaleb Y, Ortner NJ, Posch W, Fernández-Quintero ML, Tuinte WE, Monteleone S, Draheim HJ, Liedl KR, Wilflingseder D, Striessnig J, Tuluc P, Flucher BE, Campiglio M. Calcium current modulation by the γ1 subunit depends on alternative splicing of CaV1.1. J Gen Physiol 2022; 154:e202113028. [PMID: 35349630 PMCID: PMC9037348 DOI: 10.1085/jgp.202113028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 03/08/2022] [Indexed: 01/01/2023] Open
Abstract
The skeletal muscle voltage-gated calcium channel (CaV1.1) primarily functions as a voltage sensor for excitation-contraction coupling. Conversely, its ion-conducting function is modulated by multiple mechanisms within the pore-forming α1S subunit and the auxiliary α2δ-1 and γ1 subunits. In particular, developmentally regulated alternative splicing of exon 29, which inserts 19 amino acids in the extracellular IVS3-S4 loop of CaV1.1a, greatly reduces the current density and shifts the voltage dependence of activation to positive potentials outside the physiological range. We generated new HEK293 cell lines stably expressing α2δ-1, β3, and STAC3. When the adult (CaV1.1a) and embryonic (CaV1.1e) splice variants were expressed in these cells, the difference in the voltage dependence of activation observed in muscle cells was reproduced, but not the reduced current density of CaV1.1a. Only when we further coexpressed the γ1 subunit was the current density of CaV1.1a, but not that of CaV1.1e, reduced by >50%. In addition, γ1 caused a shift of the voltage dependence of inactivation to negative voltages in both variants. Thus, the current-reducing effect of γ1, unlike its effect on inactivation, is specifically dependent on the inclusion of exon 29 in CaV1.1a. Molecular structure modeling revealed several direct ionic interactions between residues in the IVS3-S4 loop and the γ1 subunit. However, substitution of these residues by alanine, individually or in combination, did not abolish the γ1-dependent reduction of current density, suggesting that structural rearrangements in CaV1.1a induced by inclusion of exon 29 may allosterically empower the γ1 subunit to exert its inhibitory action on CaV1.1 calcium currents.
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Affiliation(s)
- Yousra El Ghaleb
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Nadine J. Ortner
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Wilfried Posch
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Wietske E. Tuinte
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Stefania Monteleone
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Henning J. Draheim
- Boehringer Ingelheim Pharma GmbH & Co KG, CNS Research, Biberach an der Riss, Germany
| | - Klaus R. Liedl
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Doris Wilflingseder
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Bernhard E. Flucher
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Marta Campiglio
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
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7
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Diminished Rbfox1 increases vascular constriction by dynamically regulating alternative splicing of CaV1.2 calcium channel in hypertension. Clin Sci (Lond) 2022; 136:803-817. [PMID: 35543237 DOI: 10.1042/cs20220226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/08/2022] [Accepted: 05/10/2022] [Indexed: 11/17/2022]
Abstract
Calcium influx from depolarized CaV1.2 calcium channels triggers the contraction of vascular smooth muscle cells (VSMCs), which is important for maintaining vascular myogenic tone and blood pressure. The function of CaV1.2 channel can be subtly modulated by alternative splicing (AS), and its aberrant splicing involves in the pathogenesis of multiple cardiovascular diseases. The RNA binding protein Rbfox1 is reported to regulate the AS events of CaV1.2 channel in the neuronal development, but its potential roles in vascular CaV1.2 channels and vasoconstriction remain undefined. Here, we detect Rbfox1 is expressed in rat vascular smooth muscles. Moreover, the protein level of Rbfox1 is dramatically decreased in the hypertensive small arteries from spontaneously hypertensive rats in comparison to normotensive ones from Wistar-Kyoto rats. In VSMCs, Rbfox1 could dynamically regulate the AS of CaV1.2 exons 9* and 33. By whole-cell patch clamp, we identify knockdown of Rbfox1 induces the hyperpolarization of CaV1.2 current-voltage relationship curve in VSMCs. Furthermore, siRNA-mediated knockdown of Rbfox1 increases the K+-induced constriction of rat mesenteric arteries. In summary, our results indicate Rbfox1 modulates vascular constriction by dynamically regulating CaV1.2 alternative exons 9* and 33. Therefore, our work elucidates the underlying mechanisms for CaV1.2 channels regulation and provides a potential therapeutic target for hypertension.
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8
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Tuluc P, Theiner T, Jacobo-Piqueras N, Geisler SM. Role of High Voltage-Gated Ca 2+ Channel Subunits in Pancreatic β-Cell Insulin Release. From Structure to Function. Cells 2021; 10:2004. [PMID: 34440773 PMCID: PMC8393260 DOI: 10.3390/cells10082004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 02/07/2023] Open
Abstract
The pancreatic islets of Langerhans secrete several hormones critical for glucose homeostasis. The β-cells, the major cellular component of the pancreatic islets, secrete insulin, the only hormone capable of lowering the plasma glucose concentration. The counter-regulatory hormone glucagon is secreted by the α-cells while δ-cells secrete somatostatin that via paracrine mechanisms regulates the α- and β-cell activity. These three peptide hormones are packed into secretory granules that are released through exocytosis following a local increase in intracellular Ca2+ concentration. The high voltage-gated Ca2+ channels (HVCCs) occupy a central role in pancreatic hormone release both as a source of Ca2+ required for excitation-secretion coupling as well as a scaffold for the release machinery. HVCCs are multi-protein complexes composed of the main pore-forming transmembrane α1 and the auxiliary intracellular β, extracellular α2δ, and transmembrane γ subunits. Here, we review the current understanding regarding the role of all HVCC subunits expressed in pancreatic β-cell on electrical activity, excitation-secretion coupling, and β-cell mass. The evidence we review was obtained from many seminal studies employing pharmacological approaches as well as genetically modified mouse models. The significance for diabetes in humans is discussed in the context of genetic variations in the genes encoding for the HVCC subunits.
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Affiliation(s)
- Petronel Tuluc
- Centre for Molecular Biosciences, Department of Pharmacology and Toxicology, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; (T.T.); (N.J.-P.); (S.M.G.)
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9
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Mechanisms and Regulation of Cardiac Ca V1.2 Trafficking. Int J Mol Sci 2021; 22:ijms22115927. [PMID: 34072954 PMCID: PMC8197997 DOI: 10.3390/ijms22115927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/28/2021] [Accepted: 05/29/2021] [Indexed: 01/05/2023] Open
Abstract
During cardiac excitation contraction coupling, the arrival of an action potential at the ventricular myocardium triggers voltage-dependent L-type Ca2+ (CaV1.2) channels in individual myocytes to open briefly. The level of this Ca2+ influx tunes the amplitude of Ca2+-induced Ca2+ release from ryanodine receptors (RyR2) on the junctional sarcoplasmic reticulum and thus the magnitude of the elevation in intracellular Ca2+ concentration and ultimately the downstream contraction. The number and activity of functional CaV1.2 channels at the t-tubule dyads dictates the amplitude of the Ca2+ influx. Trafficking of these channels and their auxiliary subunits to the cell surface is thus tightly controlled and regulated to ensure adequate sarcolemmal expression to sustain this critical process. To that end, recent discoveries have revealed the existence of internal reservoirs of preformed CaV1.2 channels that can be rapidly mobilized to enhance sarcolemmal expression in times of acute stress when hemodynamic and metabolic demand increases. In this review, we provide an overview of the current thinking on CaV1.2 channel trafficking dynamics in the heart. We highlight the numerous points of control including the biosynthetic pathway, the endosomal recycling pathway, ubiquitination, and lysosomal and proteasomal degradation pathways, and discuss the effects of β-adrenergic and angiotensin receptor signaling cascades on this process.
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10
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Conrad R, Kortzak D, Guzman GA, Miranda-Laferte E, Hidalgo P. Ca V β controls the endocytic turnover of Ca V 1.2 L-type calcium channel. Traffic 2021; 22:180-193. [PMID: 33890356 DOI: 10.1111/tra.12788] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/17/2021] [Accepted: 04/17/2021] [Indexed: 01/10/2023]
Abstract
Membrane depolarization activates the multisubunit CaV 1.2 L-type calcium channel initiating various excitation coupling responses. Intracellular trafficking into and out of the plasma membrane regulates the channel's surface expression and stability, and thus, the strength of CaV 1.2-mediated Ca2+ signals. The mechanisms regulating the residency time of the channel at the cell membrane are unclear. Here, we coexpressed the channel core complex CaV 1.2α1 pore-forming and auxiliary CaV β subunits and analyzed their trafficking dynamics from single-particle-tracking trajectories. Speed histograms obtained for each subunit were best fitted to a sum of diffusive and directed motion terms. The same mean speed for the highest-mobility state underlying directed motion was found for all subunits. The frequency of this component increased by covalent linkage of CaV β to CaV 1.2α1 suggesting that high-speed transport occurs in association with CaV β. Selective tracking of CaV 1.2α1 along the postendocytic pathway failed to show the highly mobile state, implying CaV β-independent retrograde transport. Retrograde speeds of CaV 1.2α1 are compatible with myosin VI-mediated backward transport. Moreover, residency time at the cell surface was significantly prolonged when CaV 1.2α1 was covalently linked to CaV β. Thus, CaV β promotes fast transport speed along anterograde trafficking and acts as a molecular switch controlling the endocytic turnover of L-type calcium channels.
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Affiliation(s)
- Rachel Conrad
- Institute of Biological Information Processing (IBI-1), Molecular and Cellular Physiology, Forschungszentrum Jülich, Jülich, Germany
| | - Daniel Kortzak
- Institute of Biological Information Processing (IBI-1), Molecular and Cellular Physiology, Forschungszentrum Jülich, Jülich, Germany
| | - Gustavo A Guzman
- Institute of Biological Information Processing (IBI-1), Molecular and Cellular Physiology, Forschungszentrum Jülich, Jülich, Germany
| | - Erick Miranda-Laferte
- Institute of Biological Information Processing (IBI-1), Molecular and Cellular Physiology, Forschungszentrum Jülich, Jülich, Germany
| | - Patricia Hidalgo
- Institute of Biological Information Processing (IBI-1), Molecular and Cellular Physiology, Forschungszentrum Jülich, Jülich, Germany.,Institute of Biochemistry, Heinrich-Heine University, Düsseldorf, Germany
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11
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Perni S, Beam K. Neuronal junctophilins recruit specific Ca V and RyR isoforms to ER-PM junctions and functionally alter Ca V2.1 and Ca V2.2. eLife 2021; 10:64249. [PMID: 33769283 PMCID: PMC8046434 DOI: 10.7554/elife.64249] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/19/2021] [Indexed: 12/15/2022] Open
Abstract
Junctions between the endoplasmic reticulum and plasma membrane that are induced by the neuronal junctophilins are of demonstrated importance, but their molecular architecture is still poorly understood and challenging to address in neurons. This is due to the small size of the junctions and the multiple isoforms of candidate junctional proteins in different brain areas. Using colocalization of tagged proteins expressed in tsA201 cells, and electrophysiology, we compared the interactions of JPH3 and JPH4 with different calcium channels. We found that JPH3 and JPH4 caused junctional accumulation of all the tested high-voltage-activated CaV isoforms, but not a low-voltage-activated CaV. Also, JPH3 and JPH4 noticeably modify CaV2.1 and CaV2.2 inactivation rate. RyR3 moderately colocalized at junctions with JPH4, whereas RyR1 and RyR2 did not. By contrast, RyR1 and RyR3 strongly colocalized with JPH3, and RyR2 moderately. Likely contributing to this difference, JPH3 binds to cytoplasmic domain constructs of RyR1 and RyR3, but not of RyR2.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
| | - Kurt Beam
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
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12
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The life cycle of voltage-gated Ca 2+ channels in neurons: an update on the trafficking of neuronal calcium channels. Neuronal Signal 2021; 5:NS20200095. [PMID: 33664982 PMCID: PMC7905535 DOI: 10.1042/ns20200095] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/10/2021] [Accepted: 02/15/2021] [Indexed: 01/26/2023] Open
Abstract
Neuronal voltage-gated Ca2+ (CaV) channels play a critical role in cellular excitability, synaptic transmission, excitation-transcription coupling and activation of intracellular signaling pathways. CaV channels are multiprotein complexes and their functional expression in the plasma membrane involves finely tuned mechanisms, including forward trafficking from the endoplasmic reticulum (ER) to the plasma membrane, endocytosis and recycling. Whether genetic or acquired, alterations and defects in the trafficking of neuronal CaV channels can have severe physiological consequences. In this review, we address the current evidence concerning the regulatory mechanisms which underlie precise control of neuronal CaV channel trafficking and we discuss their potential as therapeutic targets.
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13
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Gandini MA, Zamponi GW. Voltage‐gated calcium channel nanodomains: molecular composition and function. FEBS J 2021; 289:614-633. [DOI: 10.1111/febs.15759] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Maria A. Gandini
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
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14
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Regulation of cardiovascular calcium channel activity by post-translational modifications or interacting proteins. Pflugers Arch 2020; 472:653-667. [PMID: 32435990 DOI: 10.1007/s00424-020-02398-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 02/08/2023]
Abstract
Voltage-gated calcium channels are the major pathway for Ca2+ influx to initiate the contraction of smooth and cardiac muscles. Alterations of calcium channel function have been implicated in multiple cardiovascular diseases, such as hypertension, atrial fibrillation, and long QT syndrome. Post-translational modifications do expand cardiovascular calcium channel structure and function to affect processes such as channel trafficking or polyubiquitination by two E3 ubiquitin ligases, Ret finger protein 2 (Rfp2) or murine double minute 2 protein (Mdm2). Additionally, biophysical property such as Ca2+-dependent inactivation (CDI) could be altered through binding of calmodulin, or channel activity could be modulated via S-nitrosylation by nitric oxide and phosphorylation by protein kinases or by interacting protein partners, such as galectin-1 and Rem. Understanding how cardiovascular calcium channel function is post-translationally remodeled under distinctive disease conditions will provide better information about calcium channel-related disease mechanisms and improve the development of more selective therapeutic agents for cardiovascular diseases.
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15
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New aspects in cardiac L-type Ca2+ channel regulation. Biochem Soc Trans 2020; 48:39-49. [PMID: 32065210 DOI: 10.1042/bst20190229] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 12/23/2022]
Abstract
Cardiac excitation-contraction coupling is initiated with the influx of Ca2+ ions across the plasma membrane through voltage-gated L-type calcium channels. This process is tightly regulated by modulation of the channel open probability and channel localization. Protein kinase A (PKA) is found in close association with the channel and is one of the main regulators of its function. Whether this kinase is modulating the channel open probability by phosphorylation of key residues or via alternative mechanisms is unclear. This review summarizes recent findings regarding the PKA-mediated channel modulation and will highlight recently discovered regulatory mechanisms that are independent of PKA activity and involve protein-protein interactions and channel localization.
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16
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Vierra NC, Kirmiz M, van der List D, Santana LF, Trimmer JS. Kv2.1 mediates spatial and functional coupling of L-type calcium channels and ryanodine receptors in mammalian neurons. eLife 2019; 8:49953. [PMID: 31663850 PMCID: PMC6839919 DOI: 10.7554/elife.49953] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
The voltage-gated K+ channel Kv2.1 serves a major structural role in the soma and proximal dendrites of mammalian brain neurons, tethering the plasma membrane (PM) to endoplasmic reticulum (ER). Although Kv2.1 clustering at neuronal ER-PM junctions (EPJs) is tightly regulated and highly conserved, its function remains unclear. By identifying and evaluating proteins in close spatial proximity to Kv2.1-containing EPJs, we discovered that a significant role of Kv2.1 at EPJs is to promote the clustering and functional coupling of PM L-type Ca2+ channels (LTCCs) to ryanodine receptor (RyR) ER Ca2+ release channels. Kv2.1 clustering also unexpectedly enhanced LTCC opening at polarized membrane potentials. This enabled Kv2.1-LTCC-RyR triads to generate localized Ca2+ release events (i.e., Ca2+ sparks) independently of action potentials. Together, these findings uncover a novel mode of LTCC regulation and establish a unique mechanism whereby Kv2.1-associated EPJs provide a molecular platform for localized somatodendritic Ca2+ signals in mammalian brain neurons.
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Affiliation(s)
- Nicholas C Vierra
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - Michael Kirmiz
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - Deborah van der List
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
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17
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Hu Z, Li G, Wang JW, Chong SY, Yu D, Wang X, Soon JL, Liang MC, Wong YP, Huang N, Colecraft HM, Liao P, Soong TW. Regulation of Blood Pressure by Targeting Ca V1.2-Galectin-1 Protein Interaction. Circulation 2019; 138:1431-1445. [PMID: 29650545 DOI: 10.1161/circulationaha.117.031231] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND L-type CaV1.2 channels play crucial roles in the regulation of blood pressure. Galectin-1 (Gal-1) has been reported to bind to the I-II loop of CaV1.2 channels to reduce their current density. However, the mechanistic understanding for the downregulation of CaV1.2 channels by Gal-1 and whether Gal-1 plays a direct role in blood pressure regulation remain unclear. METHODS In vitro experiments involving coimmunoprecipitation, Western blot, patch-clamp recordings, immunohistochemistry, and pressure myography were used to evaluate the molecular mechanisms by which Gal-1 downregulates CaV1.2 channel in transfected, human embryonic kidney 293 cells, smooth muscle cells, arteries from Lgasl1-/- mice, rat, and human patients. In vivo experiments involving the delivery of Tat-e9c peptide and AAV5-Gal-1 into rats were performed to investigate the effect of targeting CaV1.2-Gal-1 interaction on blood pressure monitored by tail-cuff or telemetry methods. RESULTS Our study reveals that Gal-1 is a key regulator for proteasomal degradation of CaV1.2 channels. Gal-1 competed allosterically with the CaVβ subunit for binding to the I-II loop of the CaV1.2 channel. This competitive disruption of CaVβ binding led to CaV1.2 degradation by exposing the channels to polyubiquitination. It is notable that we demonstrated that the inverse relationship of reduced Gal-1 and increased CaV1.2 protein levels in arteries was associated with hypertension in hypertensive rats and patients, and Gal-1 deficiency induces higher blood pressure in mice because of the upregulated CaV1.2 protein level in arteries. To directly regulate blood pressure by targeting the CaV1.2-Gal-1 interaction, we administered Tat-e9c, a peptide that competed for binding of Gal-1 by a miniosmotic pump, and this specific disruption of CaV1.2-Gal-1 coupling increased smooth muscle CaV1.2 currents, induced larger arterial contraction, and caused hypertension in rats. In contrasting experiments, overexpression of Gal-1 in smooth muscle by a single bolus of AAV5-Gal-1 significantly reduced blood pressure in spontaneously hypertensive rats. CONCLUSIONS We have defined molecularly that Gal-1 promotes CaV1.2 degradation by replacing CaVβ and thereby exposing specific lysines for polyubiquitination and by masking I-II loop endoplasmic reticulum export signals. This mechanistic understanding provided the basis for targeting CaV1.2-Gal-1 interaction to demonstrate clearly the modulatory role that Gal-1 plays in regulating blood pressure, and offering a potential approach for therapeutic management of hypertension.
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Affiliation(s)
- Zhenyu Hu
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore
| | - Guang Li
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (G.L.)
| | - Jiong-Wei Wang
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore.,Department of Surgery, Yong Loo Lin School of Medicine (J.-W.W., S.Y.C., X.W.), National University of Singapore.,Cardiovascular Research Institute, National University Heart Center, National University Health Systems, Centre for Translational Medicine, Singapore (J.-W.W., S.Y.C., X.W.)
| | - Suet Yen Chong
- Department of Surgery, Yong Loo Lin School of Medicine (J.-W.W., S.Y.C., X.W.), National University of Singapore.,Cardiovascular Research Institute, National University Heart Center, National University Health Systems, Centre for Translational Medicine, Singapore (J.-W.W., S.Y.C., X.W.)
| | - Dejie Yu
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore
| | - Xiaoyuan Wang
- Department of Surgery, Yong Loo Lin School of Medicine (J.-W.W., S.Y.C., X.W.), National University of Singapore.,Cardiovascular Research Institute, National University Heart Center, National University Health Systems, Centre for Translational Medicine, Singapore (J.-W.W., S.Y.C., X.W.)
| | | | - Mui Cheng Liang
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore
| | - Yuk Peng Wong
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore
| | - Na Huang
- National Heart Centre Singapore (J.L.S., N.H.)
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, New York (H.M.C.)
| | | | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine (Z.Y.H., J.-W.W., D.Y., M.C.L., Y.P.W., T.W.S.), National University of Singapore.,Neurobiology/Ageing Programme (T.W.S.), National University of Singapore.,Graduate School for Integrative Sciences and Engineering (T.W.S.), National University of Singapore.,National Neuroscience Institute, Singapore (T.W.S.)
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18
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Yang L, Katchman A, Kushner J, Kushnir A, Zakharov SI, Chen BX, Shuja Z, Subramanyam P, Liu G, Papa A, Roybal D, Pitt GS, Colecraft HM, Marx SO. Cardiac CaV1.2 channels require β subunits for β-adrenergic-mediated modulation but not trafficking. J Clin Invest 2019; 129:647-658. [PMID: 30422117 DOI: 10.1172/jci123878] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/06/2018] [Indexed: 01/01/2023] Open
Abstract
Ca2+ channel β-subunit interactions with pore-forming α-subunits are long-thought to be obligatory for channel trafficking to the cell surface and for tuning of basal biophysical properties in many tissues. Unexpectedly, we demonstrate that transgenic expression of mutant α1C subunits lacking capacity to bind CaVβ can traffic to the sarcolemma in adult cardiomyocytes in vivo and sustain normal excitation-contraction coupling. However, these β-less Ca2+ channels cannot be stimulated by β-adrenergic pathway agonists, and thus adrenergic augmentation of contractility is markedly impaired in isolated cardiomyocytes and in hearts. Similarly, viral-mediated expression of a β-subunit-sequestering peptide sharply curtailed β-adrenergic stimulation of WT Ca2+ channels, identifying an approach to specifically modulate β-adrenergic regulation of cardiac contractility. Our data demonstrate that β subunits are required for β-adrenergic regulation of CaV1.2 channels and positive inotropy in the heart, but are dispensable for CaV1.2 trafficking to the adult cardiomyocyte cell surface, and for basal function and excitation-contraction coupling.
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Affiliation(s)
- Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University
| | | | - Jared Kushner
- Division of Cardiology, Department of Medicine, Columbia University
| | | | | | - Bi-Xing Chen
- Division of Cardiology, Department of Medicine, Columbia University
| | - Zunaira Shuja
- Department of Physiology and Cellular Biophysics, and
| | | | - Guoxia Liu
- Division of Cardiology, Department of Medicine, Columbia University
| | - Arianne Papa
- Department of Physiology and Cellular Biophysics, and
| | - Daniel Roybal
- Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, and.,Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, Columbia University.,Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
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19
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Niu J, Yang W, Yue DT, Inoue T, Ben-Johny M. Duplex signaling by CaM and Stac3 enhances Ca V1.1 function and provides insights into congenital myopathy. J Gen Physiol 2018; 150:1145-1161. [PMID: 29950399 PMCID: PMC6080896 DOI: 10.1085/jgp.201812005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/23/2018] [Accepted: 05/11/2018] [Indexed: 01/24/2023] Open
Abstract
CaV1.1 is essential for skeletal muscle excitation-contraction coupling. Its functional expression is tuned by numerous regulatory proteins, yet underlying modulatory mechanisms remain ambiguous as CaV1.1 fails to function in heterologous systems. In this study, by dissecting channel trafficking versus gating, we evaluated the requirements for functional CaV1.1 in heterologous systems. Although coexpression of the auxiliary β subunit is sufficient for surface-membrane localization, this baseline trafficking is weak, and channels elicit a diminished open probability. The regulatory proteins calmodulin and stac3 independently enhance channel trafficking and gating via their interaction with the CaV1.1 carboxy terminus. Myopathic stac3 mutations weaken channel binding and diminish trafficking. Our findings demonstrate that multiple regulatory proteins orchestrate CaV1.1 function via duplex mechanisms. Our work also furnishes insights into the pathophysiology of stac3-associated congenital myopathy and reveals novel avenues for pharmacological intervention.
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Affiliation(s)
- Jacqueline Niu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Wanjun Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | | | - Takanari Inoue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD
- Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY
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20
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Córdova-Casanova A, Olmedo I, Riquelme J, Barrientos G, Sánchez G, Gillette T, Lavandero S, Chiong M, Donoso P, Pedrozo Z. Mechanical stretch increases L-type calcium channel stability in cardiomyocytes through a polycystin-1/AKT-dependent mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:289-296. [DOI: 10.1016/j.bbamcr.2017.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/02/2017] [Accepted: 11/03/2017] [Indexed: 12/24/2022]
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21
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Savalli N, Pantazis A, Sigg D, Weiss JN, Neely A, Olcese R. The α2δ-1 subunit remodels CaV1.2 voltage sensors and allows Ca2+ influx at physiological membrane potentials. J Gen Physiol 2017; 148:147-59. [PMID: 27481713 PMCID: PMC4969795 DOI: 10.1085/jgp.201611586] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/30/2016] [Indexed: 12/30/2022] Open
Abstract
Voltage-sensing domains (VSDs) in voltage-gated calcium channels sense the potential difference across membranes and interact with the pore to open it. Savalli et al. find that the accessory subunit α2δ-1 increases the sensitivity of VSDs I–III and also their efficiency of coupling to the pore. Excitation-evoked calcium influx across cellular membranes is strictly controlled by voltage-gated calcium channels (CaV), which possess four distinct voltage-sensing domains (VSDs) that direct the opening of a central pore. The energetic interactions between the VSDs and the pore are critical for tuning the channel’s voltage dependence. The accessory α2δ-1 subunit is known to facilitate CaV1.2 voltage-dependent activation, but the underlying mechanism is unknown. In this study, using voltage clamp fluorometry, we track the activation of the four individual VSDs in a human L-type CaV1.2 channel consisting of α1C and β3 subunits. We find that, without α2δ-1, the channel complex displays a right-shifted voltage dependence such that currents mainly develop at nonphysiological membrane potentials because of very weak VSD–pore interactions. The presence of α2δ-1 facilitates channel activation by increasing the voltage sensitivity (i.e., the effective charge) of VSDs I–III. Moreover, the α2δ-1 subunit also makes VSDs I–III more efficient at opening the channel by increasing the coupling energy between VSDs II and III and the pore, thus allowing Ca influx within the range of physiological membrane potentials.
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Affiliation(s)
- Nicoletta Savalli
- Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Antonios Pantazis
- Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | | | - James N Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095 Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095 Cardiovascular Research Laboratories, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Alan Neely
- Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095 Centro Interdisciplinario de Neurociencias de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Riccardo Olcese
- Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095 Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095 Cardiovascular Research Laboratories, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
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22
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Rosa N, Triffaux E, Robert V, Mars M, Klein M, Bouchaud G, Canivet A, Magnan A, Guéry JC, Pelletier L, Savignac M. The β and α2δ auxiliary subunits of voltage-gated calcium channel 1 (Ca v1) are required for T H2 lymphocyte function and acute allergic airway inflammation. J Allergy Clin Immunol 2017; 142:892-903.e8. [PMID: 29129580 DOI: 10.1016/j.jaci.2017.09.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/04/2017] [Accepted: 09/08/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND T lymphocytes express not only cell membrane ORAI calcium release-activated calcium modulator 1 but also voltage-gated calcium channel (Cav) 1 channels. In excitable cells these channels are composed of the ion-forming pore α1 and auxiliary subunits (β and α2δ) needed for proper trafficking and activation of the channel. Previously, we disclosed the role of Cav1.2 α1 in mouse and human TH2 but not TH1 cell functions and showed that knocking down Cav1 α1 prevents experimental asthma. OBJECTIVE We investigated the role of β and α2δ auxiliary subunits on Cav1 α1 function in TH2 lymphocytes and on the development of acute allergic airway inflammation. METHODS We used Cavβ antisense oligonucleotides to knock down Cavβ and gabapentin, a drug that binds to and inhibits α2δ1 and α2δ2, to test their effects on TH2 functions and their capacity to reduce allergic airway inflammation. RESULTS Mouse and human TH2 cells express mainly Cavβ1, β3, and α2δ2 subunits. Cavβ antisense reduces T-cell receptor-driven calcium responses and cytokine production by mouse and human TH2 cells with no effect on TH1 cells. Cavβ is mainly involved in restraining Cav1.2 α1 degradation through the proteasome because a proteasome inhibitor partially restores the α1 protein level. Gabapentin impairs the T-cell receptor-driven calcium response and cytokine production associated with the loss of α2δ2 protein in TH2 cells. CONCLUSIONS These results stress the role of Cavβ and α2δ2 auxiliary subunits in the stability and activation of Cav1.2 channels in TH2 lymphocytes both in vitro and in vivo, as demonstrated by the beneficial effect of Cavβ antisense and gabapentin in allergic airway inflammation.
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Affiliation(s)
- Nicolas Rosa
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Emily Triffaux
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Virginie Robert
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Marion Mars
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Martin Klein
- Institut du Thorax, INSERM CNRS, UNIV Nantes, France
| | | | - Astrid Canivet
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Antoine Magnan
- Institut du Thorax, INSERM CNRS, UNIV Nantes, France; Centre Hospitalier Universitaire de Nantes, Service de Pneumologie, Nantes, France
| | - Jean-Charles Guéry
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France
| | - Lucette Pelletier
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France.
| | - Magali Savignac
- Center of Physiopathology Toulouse Purpan, University Paul Sabatier Toulouse III, INSERM U1043, CNRS UMR 5282, Toulouse, France.
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23
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Mustafá ER, López Soto EJ, Martínez Damonte V, Rodríguez SS, Lipscombe D, Raingo J. Constitutive activity of the Ghrelin receptor reduces surface expression of voltage-gated Ca 2+ channels in a Ca Vβ-dependent manner. J Cell Sci 2017; 130:3907-3917. [PMID: 29038230 DOI: 10.1242/jcs.207886] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/04/2017] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated Ca2+ (CaV) channels couple membrane depolarization to Ca2+ influx, triggering a range of Ca2+-dependent cellular processes. CaV channels are, therefore, crucial in shaping neuronal activity and function, depending on their individual temporal and spatial properties. Furthermore, many neurotransmitters and drugs that act through G protein coupled receptors (GPCRs), modulate neuronal activity by altering the expression, trafficking, or function of CaV channels. GPCR-dependent mechanisms that downregulate CaV channel expression levels are observed in many neurons but are, by comparison, less studied. Here we show that the growth hormone secretagogue receptor type 1a (GHSR), a GPCR, can inhibit the forwarding trafficking of several CaV subtypes, even in the absence of agonist. This constitutive form of GPCR inhibition of CaV channels depends on the presence of a CaVβ subunit. CaVβ subunits displace CaVα1 subunits from the endoplasmic reticulum. The actions of GHSR on CaV channels trafficking suggest a role for this signaling pathway in brain areas that control food intake, reward, and learning and memory.
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Affiliation(s)
- Emilio R Mustafá
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Eduardo J López Soto
- Department of Neuroscience, Brown University; Sidney E. Frank Hall for Life Sciences, 185 Meeting Street, Providence, Rhode Island 02912, USA
| | - Valentina Martínez Damonte
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Silvia S Rodríguez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
| | - Diane Lipscombe
- Department of Neuroscience, Brown University; Sidney E. Frank Hall for Life Sciences, 185 Meeting Street, Providence, Rhode Island 02912, USA
| | - Jesica Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology (IMBICE), Universidad Nacional de La Plata - Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, and Comisión de Investigaciones de la Provincia de buenos Aires (CIC) Calle 526 1499-1579, B1906APM Tolosa, Buenos Aires, Argentina
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24
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Zhou Y, Fan J, Zhu H, Ji L, Fan W, Kapoor I, Wang Y, Wang Y, Zhu G, Wang J. Aberrant Splicing Induced by Dysregulated Rbfox2 Produces Enhanced Function of Ca V1.2 Calcium Channel and Vascular Myogenic Tone in Hypertension. Hypertension 2017; 70:1183-1192. [PMID: 28993448 DOI: 10.1161/hypertensionaha.117.09301] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 08/26/2017] [Accepted: 09/11/2017] [Indexed: 01/12/2023]
Abstract
Calcium influx from activated voltage-gated calcium channel CaV1.2 in vascular smooth muscle cells is indispensable for maintaining myogenic tone and blood pressure. The function of CaV1.2 channel can be optimized by alternative splicing, one of post-transcriptional modification mechanisms. The splicing factor Rbfox2 is known to regulate the CaV1.2 pre-mRNA alternative splicing events during neuronal development. However, Rbfox2's roles in modulating the key function of vascular CaV1.2 channel and in the pathogenesis of hypertension remain elusive. Here, we report that the proportion of CaV1.2 channels with alternative exon 9* is increased by 10.3%, whereas that with alternative exon 33 is decreased by 10.5% in hypertensive arteries. Surprisingly, the expression level of Rbfox2 is increased ≈3-folds, presumably because of the upregulation of a dominant-negative isoform of Rbfox2. In vascular smooth muscle cells, we find that knockdown of Rbfox2 dynamically increases alternative exon 9*, whereas decreases exon 33 inclusion of CaV1.2 channels. By patch-clamp studies, we show that diminished Rbfox2-induced alternative splicing shifts the steady-state activation and inactivation curves of vascular CaV1.2 calcium channel to hyperpolarization, which makes the window current potential to more negative. Moreover, siRNA-mediated knockdown of Rbfox2 increases the pressure-induced vascular myogenic tone of rat mesenteric artery. Taken together, our data indicate that Rbfox2 modulates the functions of vascular CaV1.2 calcium channel by dynamically regulating the expressions of alternative exons 9* and 33, which in turn affects the vascular myogenic tone. Therefore, our work suggests a key role for Rbfox2 in hypertension, which provides a rational basis for designing antihypertensive therapies.
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Affiliation(s)
- Yingying Zhou
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Jia Fan
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Huayuan Zhu
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Li Ji
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Wenyong Fan
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Isha Kapoor
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Yue Wang
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Yuan Wang
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Guoqing Zhu
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Juejin Wang
- From the Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (Y.Z., J.F., L.J., W.F., Yue Wang, Yuan Wang, G.Z., J.W.); Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (H.Z.); and Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.).
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25
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Findeisen F, Campiglio M, Jo H, Abderemane-Ali F, Rumpf CH, Pope L, Rossen ND, Flucher BE, DeGrado WF, Minor DL. Stapled Voltage-Gated Calcium Channel (Ca V) α-Interaction Domain (AID) Peptides Act As Selective Protein-Protein Interaction Inhibitors of Ca V Function. ACS Chem Neurosci 2017; 8:1313-1326. [PMID: 28278376 PMCID: PMC5481814 DOI: 10.1021/acschemneuro.6b00454] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
![]()
For many voltage-gated
ion channels (VGICs), creation of a properly functioning ion channel
requires the formation of specific protein–protein interactions
between the transmembrane pore-forming subunits and cystoplasmic accessory
subunits. Despite the importance of such protein–protein interactions
in VGIC function and assembly, their potential as sites for VGIC modulator
development has been largely overlooked. Here, we develop meta-xylyl (m-xylyl) stapled peptides that
target a prototypic VGIC high affinity protein–protein interaction,
the interaction between the voltage-gated calcium channel (CaV) pore-forming subunit α-interaction domain (AID) and
cytoplasmic β-subunit (CaVβ). We show using
circular dichroism spectroscopy, X-ray crystallography, and isothermal
titration calorimetry that the m-xylyl staples enhance
AID helix formation are structurally compatible with native-like AID:CaVβ interactions and reduce the entropic penalty associated
with AID binding to CaVβ. Importantly, electrophysiological
studies reveal that stapled AID peptides act as effective inhibitors
of the CaVα1:CaVβ interaction
that modulate CaV function in an CaVβ
isoform-selective manner. Together, our studies provide a proof-of-concept
demonstration of the use of protein–protein interaction inhibitors
to control VGIC function and point to strategies for improved AID-based
CaV modulator design.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Daniel L. Minor
- Molecular Biophysics & Integrated Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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26
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Trafficking of neuronal calcium channels. Neuronal Signal 2017; 1:NS20160003. [PMID: 32714572 PMCID: PMC7373241 DOI: 10.1042/ns20160003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 01/20/2017] [Accepted: 01/19/2017] [Indexed: 12/18/2022] Open
Abstract
Neuronal voltage-gated calcium channels (VGCCs) serve complex yet essential physiological functions via their pivotal role in translating electrical signals into intracellular calcium elevations and associated downstream signalling pathways. There are a number of regulatory mechanisms to ensure a dynamic control of the number of channels embedded in the plasma membrane, whereas alteration of the surface expression of VGCCs has been linked to various disease conditions. Here, we provide an overview of the mechanisms that control the trafficking of VGCCs to and from the plasma membrane, and discuss their implication in pathophysiological conditions and their potential as therapeutic targets.
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27
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Hu Z, Wang JW, Yu D, Soon JL, de Kleijn DPV, Foo R, Liao P, Colecraft HM, Soong TW. Aberrant Splicing Promotes Proteasomal Degradation of L-type Ca V1.2 Calcium Channels by Competitive Binding for Ca Vβ Subunits in Cardiac Hypertrophy. Sci Rep 2016; 6:35247. [PMID: 27731386 PMCID: PMC5059693 DOI: 10.1038/srep35247] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/27/2016] [Indexed: 12/13/2022] Open
Abstract
Decreased expression and activity of CaV1.2 calcium channels has been reported in pressure overload-induced cardiac hypertrophy and heart failure. However, the underlying mechanisms remain unknown. Here we identified in rodents a splice variant of CaV1.2 channel, named CaV1.2e21+22, that contained the pair of mutually exclusive exons 21 and 22. This variant was highly expressed in neonatal hearts. The abundance of this variant was gradually increased by 12.5-folds within 14 days of transverse aortic banding that induced cardiac hypertrophy in adult mouse hearts and was also elevated in left ventricles from patients with dilated cardiomyopathy. Although this variant did not conduct Ca2+ ions, it reduced the cell-surface expression of wild-type CaV1.2 channels and consequently decreased the whole-cell Ca2+ influx via the CaV1.2 channels. In addition, the CaV1.2e21+22 variant interacted with CaVβ subunits significantly more than wild-type CaV1.2 channels, and competition of CaVβ subunits by CaV1.2e21+22 consequently enhanced ubiquitination and subsequent proteasomal degradation of the wild-type CaV1.2 channels. Our findings show that the resurgence of a specific neonatal splice variant of CaV1.2 channels in adult heart under stress may contribute to heart failure.
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Affiliation(s)
- Zhenyu Hu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore 117597, Singapore
| | - Jiong-Wei Wang
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore.,Cardiovascular Research Institute, National University Health Systems, Centre for Translational Medicine, 117599, Singapore
| | - Dejie Yu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore 117597, Singapore
| | - Jia Lin Soon
- National Heart Centre Singapore, 5 hospital drive, 169609, Singapore
| | - Dominique P V de Kleijn
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 117597, Singapore.,Cardiovascular Research Institute, National University Health Systems, Centre for Translational Medicine, 117599, Singapore.,Dept of Cardiology, University Medical Center Utrecht, 3584CX Utrecht, The Netherlands
| | - Roger Foo
- Cardiovascular Research Institute, National University Health Systems, Centre for Translational Medicine, 117599, Singapore
| | - Ping Liao
- Calcium Signaling Laboratory, National Neuroscience Institute, 11 Jalan Tan Tock Seng 308433, Singapore
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA
| | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore 117597, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, 117456, Singapore.,Neurobiology/Ageing Programme, National University of Singapore, 117456, Singapore
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28
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Page KM, Rothwell SW, Dolphin AC. The CaVβ Subunit Protects the I-II Loop of the Voltage-gated Calcium Channel CaV2.2 from Proteasomal Degradation but Not Oligoubiquitination. J Biol Chem 2016; 291:20402-16. [PMID: 27489103 PMCID: PMC5034038 DOI: 10.1074/jbc.m116.737270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 11/06/2022] Open
Abstract
CaVβ subunits interact with the voltage-gated calcium channel CaV2.2 on a site in the intracellular loop between domains I and II (the I-II loop). This interaction influences the biophysical properties of the channel and leads to an increase in its trafficking to the plasma membrane. We have shown previously that a mutant CaV2.2 channel that is unable to bind CaVβ subunits (CaV2.2 W391A) was rapidly degraded (Waithe, D., Ferron, L., Page, K. M., Chaggar, K., and Dolphin, A. C. (2011) J. Biol. Chem. 286, 9598-9611). Here we show that, in the absence of CaVβ subunits, a construct consisting of the I-II loop of CaV2.2 was directly ubiquitinated and degraded by the proteasome system. Ubiquitination could be prevented by mutation of all 12 lysine residues in the I-II loop to arginines. Including a palmitoylation motif at the N terminus of CaV2.2 I-II loop was insufficient to target it to the plasma membrane in the absence of CaVβ subunits even when proteasomal degradation was inhibited with MG132 or ubiquitination was prevented by the lysine-to-arginine mutations. In the presence of CaVβ subunit, the palmitoylated CaV2.2 I-II loop was protected from degradation, although oligoubiquitination could still occur, and was efficiently trafficked to the plasma membrane. We propose that targeting to the plasma membrane requires a conformational change in the I-II loop that is induced by binding of the CaVβ subunit.
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Affiliation(s)
- Karen M Page
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Simon W Rothwell
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
| | - Annette C Dolphin
- From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom
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29
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Moreno C, Hermosilla T, Morales D, Encina M, Torres-Díaz L, Díaz P, Sarmiento D, Simon F, Varela D. Cavβ2 transcription start site variants modulate calcium handling in newborn rat cardiomyocytes. Pflugers Arch 2015; 467:2473-84. [PMID: 26265381 DOI: 10.1007/s00424-015-1723-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 07/17/2015] [Indexed: 12/21/2022]
Abstract
In the heart, the main pathway for calcium influx is mediated by L-type calcium channels, a multi-subunit complex composed of the pore-forming subunit CaV1.2 and the auxiliary subunits CaVα2δ1 and CaVβ2. To date, five distinct CaVβ2 transcriptional start site (TSS) variants (CaVβ2a-e) varying only in the composition and length of the N-terminal domain have been described, each of them granting distinct biophysical properties to the L-type current. However, the physiological role of these variants in Ca(2+) handling in the native tissue has not been explored. Our results show that four of these variants are present in neonatal rat cardiomyocytes. The contribution of those CaVβ2 TSS variants on endogenous L-type current and Ca(2+) handling was explored by adenoviral-mediated overexpression of each CaVβ2 variant in cultured newborn rat cardiomyocytes. As expected, all CaVβ2 TSS variants increased L-type current density and produced distinctive changes on L-type calcium channel (LTCC) current activation and inactivation kinetics. The characteristics of the induced calcium transients were dependent on the TSS variant overexpressed. Moreover, the amplitude of the calcium transients varied depending on the subunit involved, being higher in cardiomyocytes transduced with CaVβ2a and smaller in CaVβ2d. Interestingly, the contribution of Ca(2+) influx and Ca(2+) release on total calcium transients, as well as the sarcoplasmic calcium content, was found to be TSS-variant-dependent. Remarkably, determination of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) messenger RNA (mRNA) abundance and cell size change indicates that CaVβ2 TSS variants modulate the cardiomyocyte hypertrophic state. In summary, we demonstrate that expression of individual CaVβ2 TSS variants regulates calcium handling in cardiomyocytes and, consequently, has significant repercussion in the development of hypertrophy.
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Affiliation(s)
- Cristian Moreno
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Tamara Hermosilla
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Danna Morales
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Matías Encina
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Leandro Torres-Díaz
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Pablo Díaz
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile
| | - Daniela Sarmiento
- Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas and Facultad de Medicina, Universidad Andres Bello, Avenida Republica 239, Santiago, Chile
| | - Felipe Simon
- Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas and Facultad de Medicina, Universidad Andres Bello, Avenida Republica 239, Santiago, Chile.,Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Diego Varela
- Centro de Estudios Moleculares de la Célula (CEMC), Programa de Fisiopatología, Facultad de Medicina, ICBM, Universidad de Chile, Santiago, Chile.
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30
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Campiglio M, Flucher BE. The role of auxiliary subunits for the functional diversity of voltage-gated calcium channels. J Cell Physiol 2015; 230:2019-31. [PMID: 25820299 PMCID: PMC4672716 DOI: 10.1002/jcp.24998] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 03/23/2015] [Indexed: 11/18/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent the sole mechanism to convert membrane depolarization into cellular functions like secretion, contraction, or gene regulation. VGCCs consist of a pore-forming α1 subunit and several auxiliary channel subunits. These subunits come in multiple isoforms and splice-variants giving rise to a stunning molecular diversity of possible subunit combinations. It is generally believed that specific auxiliary subunits differentially regulate the channels and thereby contribute to the great functional diversity of VGCCs. If auxiliary subunits can associate and dissociate from pre-existing channel complexes, this would allow dynamic regulation of channel properties. However, most auxiliary subunits modulate current properties very similarly, and proof that any cellular calcium channel function is indeed modulated by the physiological exchange of auxiliary subunits is still lacking. In this review we summarize available information supporting a differential modulation of calcium channel functions by exchange of auxiliary subunits, as well as experimental evidence in support of alternative functions of the auxiliary subunits. At the heart of the discussion is the concept that, in their native environment, VGCCs function in the context of macromolecular signaling complexes and that the auxiliary subunits help to orchestrate the diverse protein–protein interactions found in these calcium channel signalosomes. Thus, in addition to a putative differential modulation of current properties, differential subcellular targeting properties and differential protein–protein interactions of the auxiliary subunits may explain the need for their vast molecular diversity. J. Cell. Physiol. 999: 00–00, 2015. © 2015 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. J. Cell. Physiol. 230: 2019–2031, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Marta Campiglio
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
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31
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Stölting G, de Oliveira RC, Guzman RE, Miranda-Laferte E, Conrad R, Jordan N, Schmidt S, Hendriks J, Gensch T, Hidalgo P. Direct interaction of CaVβ with actin up-regulates L-type calcium currents in HL-1 cardiomyocytes. J Biol Chem 2015; 290:4561-4572. [PMID: 25533460 PMCID: PMC4335199 DOI: 10.1074/jbc.m114.573956] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 12/05/2014] [Indexed: 12/14/2022] Open
Abstract
Expression of the β-subunit (CaVβ) is required for normal function of cardiac L-type calcium channels, and its up-regulation is associated with heart failure. CaVβ binds to the α1 pore-forming subunit of L-type channels and augments calcium current density by facilitating channel opening and increasing the number of channels in the plasma membrane, by a poorly understood mechanism. Actin, a key component of the intracellular trafficking machinery, interacts with Src homology 3 domains in different proteins. Although CaVβ encompasses a highly conserved Src homology 3 domain, association with actin has not yet been explored. Here, using co-sedimentation assays and FRET experiments, we uncover a direct interaction between CaVβ and actin filaments. Consistently, single-molecule localization analysis reveals streaklike structures composed by CaVβ2 that distribute over several micrometers along actin filaments in HL-1 cardiomyocytes. Overexpression of CaVβ2-N3 in HL-1 cells induces an increase in L-type current without altering voltage-dependent activation, thus reflecting an increased number of channels in the plasma membrane. CaVβ mediated L-type up-regulation, and CaVβ-actin association is prevented by disruption of the actin cytoskeleton with cytochalasin D. Our study reveals for the first time an interacting partner of CaVβ that is directly involved in vesicular trafficking. We propose a model in which CaVβ promotes anterograde trafficking of the L-type channels by anchoring them to actin filaments in their itinerary to the plasma membrane.
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Affiliation(s)
- Gabriel Stölting
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | | | - Raul E Guzman
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Erick Miranda-Laferte
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Rachel Conrad
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Nadine Jordan
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Silke Schmidt
- the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Johnny Hendriks
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Thomas Gensch
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and
| | - Patricia Hidalgo
- From the Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich, Germany and.
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32
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Geisler S, Schöpf CL, Obermair GJ. Emerging evidence for specific neuronal functions of auxiliary calcium channel α₂δ subunits. Gen Physiol Biophys 2014; 34:105-118. [PMID: 25504062 DOI: 10.4149/gpb_2014037] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 11/06/2014] [Indexed: 11/08/2022]
Abstract
In nerve cells the ubiquitous second messenger calcium regulates a variety of vitally important functions including neurotransmitter release, gene regulation, and neuronal plasticity. The entry of calcium into cells is tightly regulated by voltage-gated calcium channels, which consist of a heteromultimeric complex of a pore forming α₁, and the auxiliary β and α₂δ subunits. Four genes (Cacna2d1-4) encode for the extracellular membrane-attached α₂δ subunits (α₂δ-1 to α₂δ-4), out of which three isoforms (α₂δ-1 to -3) are strongly expressed in the central nervous system. Over the years a wealth of studies has demonstrated the classical role of α₂δ subunits in channel trafficking and calcium current modulation. Recent studies in specialized neuronal cell systems propose roles of α₂δ subunits beyond the classical view and implicate α₂δ subunits as important regulators of synapse formation. These findings are supported by the identification of novel human disease mutations associated with α₂δ subunits and by the fact that α₂δ subunits are the target of the anti-epileptic and anti-allodynic drugs gabapentin and pregabalin. Here we review the recently emerging evidence for specific as well as redundant neuronal roles of α₂δ subunits and discuss the mechanisms for establishing and maintaining specificity.
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Affiliation(s)
- Stefanie Geisler
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Clemens L Schöpf
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Gerald J Obermair
- Division of Physiology, Department of Physiology and Medical Physics, Medical University Innsbruck, 6020 Innsbruck, Austria
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Aromolaran AS, Subramanyam P, Chang DD, Kobertz WR, Colecraft HM. LQT1 mutations in KCNQ1 C-terminus assembly domain suppress IKs using different mechanisms. Cardiovasc Res 2014; 104:501-11. [PMID: 25344363 DOI: 10.1093/cvr/cvu231] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIMS Long QT syndrome 1 (LQT1) mutations in KCNQ1 that decrease cardiac IKs (slowly activating delayed rectifier K(+) current) underlie ventricular arrhythmias and sudden death. LQT1 mutations may suppress IKs by preventing KCNQ1 assembly, disrupting surface trafficking, or inhibiting gating. We investigated mechanisms underlying how three LQT1 mutations in KCNQ1 C-terminus assembly domain (R555H/G589D/L619M) decrease IKs in heterologous cells and cardiomyocytes. METHODS AND RESULTS In Chinese hamster ovary (CHO) cells, mutant KCNQ1 + KCNE1 channels either produced no currents (G589D/L619M) or displayed markedly reduced IKs with a right-shifted voltage-dependence of activation (R555H). When co-expressed with wild-type (wt) KCNQ1, the mutant KCNQ1s displayed varying intrinsic dominant-negative capacities that were affected by auxiliary KCNE1. All three mutant KCNQ1s assembled with wt KCNQ1 as determined by fluorescence resonance energy transfer (FRET). We developed an optical quantum dot labelling assay to measure channel surface density. G589D/R555H displayed substantial reductions in surface density, which were either partially (G589D) or fully (R555H) rescued by wt KCNQ1. Unexpectedly, L619M showed no trafficking defect. In adult rat cardiomyocytes, adenovirus-expressed homotetrameric G589D/L619M + KCNE1 channels yielded no currents, whereas R555H + KCNE1 produced diminished IKs with a right-shifted voltage-dependence of activation, mimicking observations in CHO cells. In contrast to heterologous cells, homotetrameric R555H channels showed no trafficking defect in cardiomyocytes. CONCLUSION Distinct LQT1 mutations in KCNQ1 assembly domain decrease IKs using unique combinations of biophysical and trafficking mechanisms. Functional deficits in IKs observed in heterologous cells are mostly, but not completely, recapitulated in adult rat cardiomyocytes. A 'methodological chain' combining approaches in heterologous cells and cardiomyocytes provides mechanistic insights that may help advance personalized therapy for LQT1 mutations.
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Affiliation(s)
- Ademuyiwa S Aromolaran
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - Prakash Subramanyam
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - Donald D Chang
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
| | - William R Kobertz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, MA 01605, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, 504 Russ Berrie, New York, NY 10032, USA
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Subramanyam P, Colecraft HM. Ion channel engineering: perspectives and strategies. J Mol Biol 2014; 427:190-204. [PMID: 25205552 DOI: 10.1016/j.jmb.2014.09.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/01/2014] [Indexed: 01/19/2023]
Abstract
Ion channels facilitate the passive movement of ions down an electrochemical gradient and across lipid bilayers in cells. This phenomenon is essential for life and underlies many critical homeostatic processes in cells. Ion channels are diverse and differ with respect to how they open and close (gating) and to their ionic conductance/selectivity (permeation). Fundamental understanding of ion channel structure-function mechanisms, their physiological roles, how their dysfunction leads to disease, their utility as biosensors, and development of novel molecules to modulate their activity are important and active research frontiers. In this review, we focus on ion channel engineering approaches that have been applied to investigate these aspects of ion channel function, with a major emphasis on voltage-gated ion channels.
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Affiliation(s)
- Prakash Subramanyam
- Department of Physiology and Cellular Biophysics, Columbia University, NY, 10032, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, NY, 10032, USA.
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Neely A, Hidalgo P. Structure-function of proteins interacting with the α1 pore-forming subunit of high-voltage-activated calcium channels. Front Physiol 2014; 5:209. [PMID: 24917826 PMCID: PMC4042065 DOI: 10.3389/fphys.2014.00209] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 05/15/2014] [Indexed: 11/13/2022] Open
Abstract
Openings of high-voltage-activated (HVA) calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, HVA calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1) associated with four additional polypeptide chains β, α2, δ, and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of HVA calcium channels.
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Affiliation(s)
- Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso and Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Patricia Hidalgo
- Forschungszentrum Jülich, Institute of Complex Systems 4, Zelluläre Biophysik Jülich, Germany
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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Dawson TF, Boone AN, Senatore A, Piticaru J, Thiyagalingam S, Jackson D, Davison A, Spafford JD. Gene splicing of an invertebrate beta subunit (LCavβ) in the N-terminal and HOOK domains and its regulation of LCav1 and LCav2 calcium channels. PLoS One 2014; 9:e92941. [PMID: 24690951 PMCID: PMC3972191 DOI: 10.1371/journal.pone.0092941] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 02/27/2014] [Indexed: 01/31/2023] Open
Abstract
The accessory beta subunit (Ca(v)β) of calcium channels first appear in the same genome as Ca(v)1 L-type calcium channels in single-celled coanoflagellates. The complexity of this relationship expanded in vertebrates to include four different possible Ca(v)β subunits (β1, β2, β3, β4) which associate with four Ca(v)1 channel isoforms (Ca(v)1.1 to Ca(v)1.4) and three Ca(v)2 channel isoforms (Ca(v)2.1 to Ca(v)2.3). Here we assess the fundamentally-shared features of the Ca(v)β subunit in an invertebrate model (pond snail Lymnaea stagnalis) that bears only three homologous genes: (LCa(v)1, LCa(v)2, and LCa(v)β). Invertebrate Ca(v)β subunits (in flatworms, snails, squid and honeybees) slow the inactivation kinetics of Ca(v)2 channels, and they do so with variable N-termini and lacking the canonical palmitoylation residues of the vertebrate β2a subunit. Alternative splicing of exon 7 of the HOOK domain is a primary determinant of a slow inactivation kinetics imparted by the invertebrate LCa(v)β subunit. LCa(v)β will also slow the inactivation kinetics of LCa(v)3 T-type channels, but this is likely not physiologically relevant in vivo. Variable N-termini have little influence on the voltage-dependent inactivation kinetics of differing invertebrate Ca(v)β subunits, but the expression pattern of N-terminal splice isoforms appears to be highly tissue specific. Molluscan LCa(v)β subunits have an N-terminal "A" isoform (coded by exons: 1a and 1b) that structurally resembles the muscle specific variant of vertebrate β1a subunit, and has a broad mRNA expression profile in brain, heart, muscle and glands. A more variable "B" N-terminus (exon 2) in the exon position of mammalian β3 and has a more brain-centric mRNA expression pattern. Lastly, we suggest that the facilitation of closed-state inactivation (e.g. observed in Ca(v)2.2 and Ca(v)β3 subunit combinations) is a specialization in vertebrates, because neither snail subunit (LCa(v)2 nor LCa(v)β) appears to be compatible with this observed property.
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Affiliation(s)
- Taylor F. Dawson
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Adrienne N. Boone
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Adriano Senatore
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Joshua Piticaru
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | | | - Daniel Jackson
- Institute of Genetics, School of Biology, University of Nottingham, Nottingham, United Kingdom
| | - Angus Davison
- Institute of Genetics, School of Biology, University of Nottingham, Nottingham, United Kingdom
| | - J. David Spafford
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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Abstract
In this article, we focus on a refinement of the traditional voltage-clamp methods that are used to measure current from whole cells, or relatively large areas of membrane, called the patch-clamp technique. Although this technique has extended the application of voltage-clamp methods to the recording of ionic currents flowing through single channels, in its whole-cell configuration it has become the most widely used method for recording ionic currents. We give particular attention to the study of voltage-gated (CaV) Ca(2+) channels using the patch-clamp technique and discuss some aspects of the molecular physiology of these proteins.
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Striessnig J, Pinggera A, Kaur G, Bock G, Tuluc P. L-type Ca 2+ channels in heart and brain. ACTA ACUST UNITED AC 2014; 3:15-38. [PMID: 24683526 PMCID: PMC3968275 DOI: 10.1002/wmts.102] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
L-type calcium channels (Cav1) represent one of the three major classes (Cav1–3) of voltage-gated calcium channels. They were identified as the target of clinically used calcium channel blockers (CCBs; so-called calcium antagonists) and were the first class accessible to biochemical characterization. Four of the 10 known α1 subunits (Cav1.1–Cav1.4) form the pore of L-type calcium channels (LTCCs) and contain the high-affinity drug-binding sites for dihydropyridines and other chemical classes of organic CCBs. In essentially all electrically excitable cells one or more of these LTCC isoforms is expressed, and therefore it is not surprising that many body functions including muscle, brain, endocrine, and sensory function depend on proper LTCC activity. Gene knockouts and inherited human diseases have allowed detailed insight into the physiological and pathophysiological role of these channels. Genome-wide association studies and analysis of human genomes are currently providing even more hints that even small changes of channel expression or activity may be associated with disease, such as psychiatric disease or cardiac arrhythmias. Therefore, it is important to understand the structure–function relationship of LTCC isoforms, their differential contribution to physiological function, as well as their fine-tuning by modulatory cellular processes.
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Affiliation(s)
- Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Alexandra Pinggera
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gurjot Kaur
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gabriella Bock
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
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Manipulating L-type calcium channels in cardiomyocytes using split-intein protein transsplicing. Proc Natl Acad Sci U S A 2013; 110:15461-6. [PMID: 24003157 DOI: 10.1073/pnas.1308161110] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Manipulating expression of large genes (>6 kb) in adult cardiomyocytes is challenging because these cells are only efficiently transduced by viral vectors with a 4-7 kb packaging capacity. This limitation impedes understanding structure-function mechanisms of important proteins in heart. L-type calcium channels (LTCCs) regulate diverse facets of cardiac physiology including excitation-contraction coupling, excitability, and gene expression. Many important questions about how LTCCs mediate such multidimensional signaling are best resolved by manipulating expression of the 6.6 kb pore-forming α1C-subunit in adult cardiomyocytes. Here, we use split-intein-mediated protein transsplicing to reconstitute LTCC α1C-subunit from two distinct halves, overcoming the difficulty of expressing full-length α1C in cardiomyocytes. Split-intein-tagged α1C fragments encoding dihydropyridine-resistant channels were incorporated into adenovirus and reconstituted in cardiomyocytes. Similar to endogenous LTCCs, recombinant channels targeted to dyads, triggered Ca(2+) transients, associated with caveolin-3, and supported β-adrenergic regulation of excitation-contraction coupling. This approach lowers a longstanding technical hurdle to manipulating large proteins in cardiomyocytes.
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Felix R, Calderón-Rivera A, Andrade A. Regulation of high-voltage-activated Ca 2+ channel function, trafficking, and membrane stability by auxiliary subunits. ACTA ACUST UNITED AC 2013; 2:207-220. [PMID: 24949251 DOI: 10.1002/wmts.93] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Voltage-gated Ca2+ (CaV) channels mediate Ca2+ ions influx into cells in response to depolarization of the plasma membrane. They are responsible for initiation of excitation-contraction and excitation-secretion coupling, and the Ca2+ that enters cells through this pathway is also important in the regulation of protein phosphorylation, gene transcription, and many other intracellular events. Initial electrophysiological studies divided CaV channels into low-voltage-activated (LVA) and high-voltage-activated (HVA) channels. The HVA CaV channels were further subdivided into L, N, P/Q, and R-types which are oligomeric protein complexes composed of an ion-conducting CaVα1 subunit and auxiliary CaVα2δ, CaVβ, and CaVγ subunits. The functional consequences of the auxiliary subunits include altered functional and pharmacological properties of the channels as well as increased current densities. The latter observation suggests an important role of the auxiliary subunits in membrane trafficking of the CaVα1 subunit. This includes the mechanisms by which CaV channels are targeted to the plasma membrane and to appropriate regions within a given cell. Likewise, the auxiliary subunits seem to participate in the mechanisms that remove CaV channels from the plasma membrane for recycling and/or degradation. Diverse studies have provided important clues to the molecular mechanisms involved in the regulation of CaV channels by the auxiliary subunits, and the roles that these proteins could possibly play in channel targeting and membrane Stabilization.
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Affiliation(s)
- Ricardo Felix
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico
| | - Aida Calderón-Rivera
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico
| | - Arturo Andrade
- Department of Neuroscience, Brown University, Providence, RI, USA
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Wen D, Cornelius RJ, Yuan Y, Sansom SC. Regulation of BK-α expression in the distal nephron by aldosterone and urine pH. Am J Physiol Renal Physiol 2013; 305:F463-76. [PMID: 23761673 DOI: 10.1152/ajprenal.00171.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In the distal nephron, the large-conductance Ca-activated K (BK) channel, comprised of a pore-forming-α (BK-α) and the BK-β4 subunit, promotes K excretion when mice are maintained on a high-K alkaline diet (HK-alk). We examined whether BK-β4 and the acid-base status regulate apical membrane expression of BK-α in the cortical (CCD) and medullary collecting ducts (MCD) using immunohistochemical analysis (IHC) and Western blot. With the use of IHC, BK-α of mice on acontrol diet localized mostly cytoplasmically in intercalated cells (IC) of the CCD and in the perinuclear region of both principle cells (PC) and IC of the MCD. HK-alk wild-type mice (WT), but not BK-β4 knockout mice (β4KO), exhibited increased apical BK-α in both the CCD and MCD. When given a high-K acidic diet (HK-Cl), BK-α expression increased but remained cytoplasmic in the CCD and perinuclear in the MCD of both WT and β4KO. Western blot confirmed that total BK-α expression was enhanced by either HK-alk or HK-Cl but only increased in the plasma membrane with HK-alk. Compared with controls, mice drinking NaHCO3 water exhibited more apical BK-α and total cellular BK-β4. Spironolactone given to mice on HK-alk significantly reduced K secretion and decreased total cellular BK-α but did not affect cellular BK-β4 and apical BK-α. Experiments with MDCK-C11 cells indicated that BK-β4 stabilizes surface BK-α by inhibiting degradation through a lysosomal pathway. These data suggest that aldosterone mediates a high-K-induced increase in BK-α and urinary alkalinization increases BK-β4 expression, which promotes the apical localization of BK-α.
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Affiliation(s)
- Donghai Wen
- Dept. of Cellular and Integrative Physiology, 985850 Nebraska Medical Center, Omaha, NE 68198-5850.
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Ca2+ channel and Na+/Ca2+ exchange localization in cardiac myocytes. J Mol Cell Cardiol 2013; 58:22-31. [DOI: 10.1016/j.yjmcc.2012.11.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 11/20/2012] [Accepted: 11/28/2012] [Indexed: 01/01/2023]
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Zhang SS, Shaw RM. Multilayered regulation of cardiac ion channels. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1833:876-85. [PMID: 23103513 PMCID: PMC3568256 DOI: 10.1016/j.bbamcr.2012.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 12/27/2022]
Abstract
Essential to beat-to-beat heart function is the ability for cardiomyocytes to propagate electrical excitation and generate contractile force. Both excitation and contractility depend on specific ventricular ion channels, which include the L-type calcium channel (LTCC) and the connexin 43 (Cx43) gap junction. Each of these two channels is localized to a distinct subdomain of the cardiomyocyte plasma membrane. In this review, we focus on regulatory mechanisms that govern the lifecycles of LTCC and Cx43, from their biogenesis in the nucleus to directed delivery to T-tubules and intercalated discs, respectively. We discuss recent findings on how alternative promoter usage, tissue-specific transcription, and alternative splicing determine precise ion channel expression levels within a cardiomyocyte. Moreover, recent work on microtubule and actin-dependent trafficking for Cx43 and LTCC are introduced. Lastly, we discuss how human cardiac disease phenotypes can be attributed to defects in distinct mechanisms of channel regulation at the level of gene expression and channel trafficking. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Shan-Shan Zhang
- University of California, San Francisco, San Francisco, CA 94158, USA
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Shaw RM, Colecraft HM. L-type calcium channel targeting and local signalling in cardiac myocytes. Cardiovasc Res 2013; 98:177-86. [PMID: 23417040 DOI: 10.1093/cvr/cvt021] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In the heart, Ca(2+) influx via Ca(V)1.2 L-type calcium channels (LTCCs) is a multi-functional signal that triggers muscle contraction, controls action potential duration, and regulates gene expression. The use of LTCC Ca(2+) as a multi-dimensional signalling molecule in the heart is complicated by several aspects of cardiac physiology. Cytosolic Ca(2+) continuously cycles between ~100 nM and ~1 μM with each heartbeat due to Ca(2+) linked signalling from LTCCs to ryanodine receptors. This rapid cycling raises the question as to how cardiac myocytes distinguish the Ca(2+) fluxes originating through L-type channels that are dedicated to contraction from Ca(2+) fluxes originating from other L-type channels that are used for non-contraction-related signalling. In general, disparate Ca(2+) sources in cardiac myocytes such as current through differently localized LTCCs as well as from IP3 receptors can signal selectively to Ca(2+)-dependent effectors in local microdomains that can be impervious to the cytoplasmic Ca(2+) transients that drive contraction. A particular challenge for diversified signalling via cardiac LTCCs is that they are voltage-gated and, therefore, open and presumably flood their microdomains with Ca(2+) with each action potential. Thus spatial localization of Cav1.2 channels to different types of microdomains of the ventricular cardiomyocyte membrane as well as the existence of particular macromolecular complexes in each Cav1.2 microdomain are important to effect different types of Cav1.2 signalling. In this review we examine aspects of Cav1.2 structure, targeting and signalling in two specialized membrane microdomains--transverse tubules and caveolae.
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Affiliation(s)
- Robin M Shaw
- Cardiovascular Research Institute and Department of Medicine, University of California, San Francisco, CA 94143, USA
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Chan JD, Zarowiecki M, Marchant JS. Ca²⁺ channels and praziquantel: a view from the free world. Parasitol Int 2012; 62:619-28. [PMID: 23246536 DOI: 10.1016/j.parint.2012.12.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 12/06/2012] [Indexed: 01/22/2023]
Abstract
Targeting the cellular Ca(2+) channels and pumps that underpin parasite Ca(2+) homeostasis may realize novel antihelmintic agents. Indeed, the antischistosomal drug praziquantel (PZQ) is a key clinical agent that has been proposed to work in this manner. Heterologous expression data has implicated an action of PZQ on voltage-operated Ca(2+) channels, although the relevant in vivo target of this drug has remained undefined over three decades of clinical use. The purpose of this review is to bring new perspective to this issue by discussing the potential utility of free-living planarian flatworms for providing new insight into the mechanism of PZQ action. First, we discuss in vivo functional genetic data from the planarian system that broadly supports the molecular data collected in heterologous systems and the 'Ca(2+) hypothesis' of PZQ action. On the basis of these similarities we highlight our current knowledge of platyhelminth voltage operated Ca(2+) channels, their unique molecular pharmacology and the downstream functional PZQ interactome engaged by dysregulation of Ca(2+) influx that has potential to yield novel antischistosomal targets. Overall the broad dataset underscores a common theme of PZQ-evoked disruptions of Ca(2+) homeostasis in trematodes, cestodes and turbellarians, and showcases the utility of the planarian model for deriving insight into drug action and targets in parasitic flatworms.
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Affiliation(s)
- John D Chan
- Department of Pharmacology, University of Minnesota Medical School, MN 55455, USA; The Stem Cell Institute, University of Minnesota Medical School, MN 55455, USA
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Zamponi GW, Currie KPM. Regulation of Ca(V)2 calcium channels by G protein coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1629-43. [PMID: 23063655 DOI: 10.1016/j.bbamem.2012.10.004] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/02/2012] [Accepted: 10/04/2012] [Indexed: 12/29/2022]
Abstract
Voltage gated calcium channels (Ca²⁺ channels) are key mediators of depolarization induced calcium influx into excitable cells, and thereby play pivotal roles in a wide array of physiological responses. This review focuses on the inhibition of Ca(V)2 (N- and P/Q-type) Ca²⁺-channels by G protein coupled receptors (GPCRs), which exerts important autocrine/paracrine control over synaptic transmission and neuroendocrine secretion. Voltage-dependent inhibition is the most widespread mechanism, and involves direct binding of the G protein βγ dimer (Gβγ) to the α1 subunit of Ca(V)2 channels. GPCRs can also recruit several other distinct mechanisms including phosphorylation, lipid signaling pathways, and channel trafficking that result in voltage-independent inhibition. Current knowledge of Gβγ-mediated inhibition is reviewed, including the molecular interactions involved, determinants of voltage-dependence, and crosstalk with other cell signaling pathways. A summary of recent developments in understanding the voltage-independent mechanisms prominent in sympathetic and sensory neurons is also included. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology & Pharmacology, Hotchkiss Brain Institute, University of Calgary, Canada
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Yang T, Colecraft HM. Regulation of voltage-dependent calcium channels by RGK proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1644-54. [PMID: 23063948 DOI: 10.1016/j.bbamem.2012.10.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 12/28/2022]
Abstract
RGK proteins belong to the Ras superfamily of monomeric G-proteins, and currently include four members - Rad, Rem, Rem2, and Gem/Kir. RGK proteins are broadly expressed, and are the most potent known intracellular inhibitors of high-voltage-activated Ca²⁺ (Ca(V)1 and Ca(V)2) channels. Here, we review and discuss the evidence in the literature regarding the functional mechanisms, structural determinants, physiological role, and potential practical applications of RGK-mediated inhibition of Ca(V)1/Ca(V)2 channels. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Tingting Yang
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, New York, NY 10032, USA
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Buraei Z, Yang J. Structure and function of the β subunit of voltage-gated Ca²⁺ channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1530-40. [PMID: 22981275 DOI: 10.1016/j.bbamem.2012.08.028] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 08/22/2012] [Accepted: 08/25/2012] [Indexed: 12/31/2022]
Abstract
The voltage-gated Ca²⁺ channel β subunit (Ca(v)β) is a cytosolic auxiliary subunit that plays an essential role in regulating the surface expression and gating properties of high-voltage activated (HVA) Ca²⁺ channels. It is also crucial for the modulation of HVA Ca²⁺ channels by G proteins, kinases, Ras-related RGK GTPases, and other proteins. There are indications that Ca(v)β may carry out Ca²⁺ channel-independent functions. Ca(v)β knockouts are either non-viable or result in a severe pathophysiology, and mutations in Ca(v)β have been implicated in disease. In this article, we review the structure and various biological functions of Ca(v)β, as well as recent advances. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Zafir Buraei
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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Swaminathan PD, Purohit A, Hund TJ, Anderson ME. Calmodulin-dependent protein kinase II: linking heart failure and arrhythmias. Circ Res 2012; 110:1661-77. [PMID: 22679140 DOI: 10.1161/circresaha.111.243956] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Understanding relationships between heart failure and arrhythmias, important causes of suffering and sudden death, remains an unmet goal for biomedical researchers and physicians. Evidence assembled over the past decade supports a view that activation of the multifunctional Ca(2+) and calmodulin-dependent protein kinase II (CaMKII) favors myocardial dysfunction and cell membrane electrical instability. CaMKII activation follows increases in intracellular Ca(2+) or oxidation, upstream signals with the capacity to transition CaMKII into a Ca(2+) and calmodulin-independent constitutively active enzyme. Constitutively active CaMKII appears poised to participate in disease pathways by catalyzing the phosphorylation of classes of protein targets important for excitation-contraction coupling and cell survival, including ion channels and Ca(2+) homeostatic proteins, and transcription factors that drive hypertrophic and inflammatory gene expression. This rich diversity of downstream targets helps to explain the potential for CaMKII to simultaneously affect mechanical and electrical properties of heart muscle cells. Proof-of-concept studies from a growing number of investigators show that CaMKII inhibition is beneficial for improving myocardial performance and for reducing arrhythmias. We review the molecular physiology of CaMKII and discuss CaMKII actions at key cellular targets and results of animal models of myocardial hypertrophy, dysfunction, and arrhythmias that suggest CaMKII inhibition may benefit myocardial function while reducing arrhythmias.
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Affiliation(s)
- Paari Dominic Swaminathan
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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