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Despang P, Salamon S, Breitenkamp A, Kuzmenkina E, Matthes J. Inhibitory effects on L- and N-type calcium channels by a novel Ca Vβ 1 variant identified in a patient with autism spectrum disorder. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2022; 395:459-470. [PMID: 35122502 PMCID: PMC8873119 DOI: 10.1007/s00210-022-02213-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/25/2022] [Indexed: 12/01/2022]
Abstract
Voltage-gated calcium channel (VGCC) subunits have been genetically associated with autism spectrum disorders (ASD). The properties of the pore-forming VGCC subunit are modulated by auxiliary β-subunits, which exist in four isoforms (CaVβ1-4). Our previous findings suggested that activation of L-type VGCCs is a common feature of CaVβ2 subunit mutations found in ASD patients. In the current study, we functionally characterized a novel CaVβ1b variant (p.R296C) identified in an ASD patient. We used whole-cell and single-channel patch clamp to study the effect of CaVβ1b_R296C on the function of L- and N-type VGCCs. Furthermore, we used co-immunoprecipitation followed by Western blot to evaluate the interaction of the CaVβ1b-subunits with the RGK-protein Gem. Our data obtained at both, whole-cell and single-channel levels, show that compared to a wild-type CaVβ1b, the CaVβ1b_R296C variant inhibits L- and N-type VGCCs. Interaction with and modulation by the RGK-protein Gem seems to be intact. Our findings indicate functional effects of the CaVβ1b_R296C variant differing from that attributed to CaVβ2 variants found in ASD patients. Further studies have to detail the effects on different VGCC subtypes and on VGCC expression.
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Affiliation(s)
- Patrick Despang
- Center of Pharmacology, Institute II, University of Cologne, Gleueler Strasse 24, 50931, Köln, Cologne, Germany
| | - Sarah Salamon
- Center of Pharmacology, Institute II, University of Cologne, Gleueler Strasse 24, 50931, Köln, Cologne, Germany
| | - Alexandra Breitenkamp
- Center of Pharmacology, Institute II, University of Cologne, Gleueler Strasse 24, 50931, Köln, Cologne, Germany
| | - Elza Kuzmenkina
- Center of Pharmacology, Institute II, University of Cologne, Gleueler Strasse 24, 50931, Köln, Cologne, Germany
| | - Jan Matthes
- Center of Pharmacology, Institute II, University of Cologne, Gleueler Strasse 24, 50931, Köln, Cologne, Germany.
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2
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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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3
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Pickel S, Cruz-Garcia Y, Bandleon S, Barkovits K, Heindl C, Völker K, Abeßer M, Pfeiffer K, Schaaf A, Marcus K, Eder-Negrin P, Kuhn M, Miranda-Laferte E. The β 2-Subunit of Voltage-Gated Calcium Channels Regulates Cardiomyocyte Hypertrophy. Front Cardiovasc Med 2021; 8:704657. [PMID: 34307509 PMCID: PMC8292724 DOI: 10.3389/fcvm.2021.704657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 06/09/2021] [Indexed: 12/16/2022] Open
Abstract
L-type voltage-gated calcium channels (LTCCs) regulate crucial physiological processes in the heart. They are composed of the Cavα1 pore-forming subunit and the accessory subunits Cavβ, Cavα2δ, and Cavγ. Cavβ is a cytosolic protein that regulates channel trafficking and activity, but it also exerts other LTCC-independent functions. Cardiac hypertrophy, a relevant risk factor for the development of congestive heart failure, depends on the activation of calcium-dependent pro-hypertrophic signaling cascades. Here, by using shRNA-mediated Cavβ silencing, we demonstrate that Cavβ2 downregulation enhances α1-adrenergic receptor agonist-induced cardiomyocyte hypertrophy. We report that a pool of Cavβ2 is targeted to the nucleus in cardiomyocytes and that the expression of this nuclear fraction decreases during in vitro and in vivo induction of cardiac hypertrophy. Moreover, the overexpression of nucleus-targeted Cavβ2 in cardiomyocytes inhibits in vitro-induced hypertrophy. Quantitative proteomic analyses showed that Cavβ2 knockdown leads to changes in the expression of diverse myocyte proteins, including reduction of calpastatin, an endogenous inhibitor of the calcium-dependent protease calpain. Accordingly, Cavβ2-downregulated cardiomyocytes had a 2-fold increase in calpain activity as compared to control cells. Furthermore, inhibition of calpain activity in Cavβ2-downregulated cells abolished the enhanced α1-adrenergic receptor agonist-induced hypertrophy observed in these cells. Our findings indicate that in cardiomyocytes, a nuclear pool of Cavβ2 participates in cellular functions that are independent of LTCC activity. They also indicate that a downregulation of nuclear Cavβ2 during cardiomyocyte hypertrophy promotes the activation of calpain-dependent hypertrophic pathways.
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Affiliation(s)
- Simone Pickel
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | | | - Sandra Bandleon
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Katalin Barkovits
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Cornelia Heindl
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Katharina Völker
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Marco Abeßer
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Kathy Pfeiffer
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Alice Schaaf
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Katrin Marcus
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Petra Eder-Negrin
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany.,Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Erick Miranda-Laferte
- Institute of Physiology, University of Würzburg, Würzburg, Germany.,Institut für Biologische Informationsprozesse, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
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4
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Sanchez-Alonso JL, Loucks A, Schobesberger S, van Cromvoirt AM, Poulet C, Chowdhury RA, Trayanova N, Gorelik J. Nanoscale regulation of L-type calcium channels differentiates between ischemic and dilated cardiomyopathies. EBioMedicine 2020; 57:102845. [PMID: 32580140 PMCID: PMC7317229 DOI: 10.1016/j.ebiom.2020.102845] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Subcellular localization and function of L-type calcium channels (LTCCs) play an important role in regulating contraction of cardiomyocytes. Understanding how this is affected by the disruption of transverse tubules during heart failure could lead to new insights into the disease. METHODS Cardiomyocytes were isolated from healthy donor hearts, as well as from patients with cardiomyopathies and with left ventricular assist devices. Scanning ion conductance and confocal microscopy was used to study membrane structures in the cells. Super-resolution scanning patch-clamp was used to examine LTCC function in different microdomains. Computational modeling predicted the impact of these changes to arrhythmogenesis at the whole-heart level. FINDINGS We showed that loss of structural organization in failing myocytes leads to re-distribution of functional LTCCs from the T-tubules to the sarcolemma. In ischemic cardiomyopathy, the increased LTCC open probability in the T-tubules depends on the phosphorylation by protein kinase A, whereas in dilated cardiomyopathy, the increased LTCC opening probability in the sarcolemma results from enhanced phosphorylation by calcium-calmodulin kinase II. LVAD implantation corrected LTCCs pathophysiological activity, although it did not improve their distribution. Using computational modeling in a 3D anatomically-realistic human ventricular model, we showed how LTCC location and activity can trigger heart rhythm disorders of different severity. INTERPRETATION Our findings demonstrate that LTCC redistribution and function differentiate between disease aetiologies. The subcellular changes observed in specific microdomains could be the consequence of the action of distinct protein kinases. FUNDING This work was supported by NIH grant (ROI-HL 126802 to NT-JG) and British Heart Foundation (grant RG/17/13/33173 to JG, project grant PG/16/17/32069 to RAC). Funders had no role in study design, data collection, data analysis, interpretation, writing of the report.
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Affiliation(s)
- Jose L Sanchez-Alonso
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Alexandra Loucks
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sophie Schobesberger
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Ankie M van Cromvoirt
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Claire Poulet
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Rasheda A Chowdhury
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Natalia Trayanova
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Julia Gorelik
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK.
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5
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Autism-associated mutations in the CaVβ2 calcium-channel subunit increase Ba2+-currents and lead to differential modulation by the RGK-protein Gem. Neurobiol Dis 2020; 136:104721. [DOI: 10.1016/j.nbd.2019.104721] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 12/06/2019] [Accepted: 12/26/2019] [Indexed: 12/26/2022] Open
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Hegyi B, Morotti S, Liu C, Ginsburg KS, Bossuyt J, Belardinelli L, Izu LT, Chen-Izu Y, Bányász T, Grandi E, Bers DM. Enhanced Depolarization Drive in Failing Rabbit Ventricular Myocytes: Calcium-Dependent and β-Adrenergic Effects on Late Sodium, L-Type Calcium, and Sodium-Calcium Exchange Currents. Circ Arrhythm Electrophysiol 2019; 12:e007061. [PMID: 30879336 PMCID: PMC6720130 DOI: 10.1161/circep.118.007061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heart failure (HF) is characterized by electrophysiological remodeling resulting in increased risk of cardiac arrhythmias. Previous reports suggest that elevated inward ionic currents in HF promote action potential (AP) prolongation, increased short-term variability of AP repolarization, and delayed afterdepolarizations. However, the underlying changes in late Na+ current (INaL), L-type Ca2+ current, and NCX (Na+/Ca2+ exchanger) current are often measured in nonphysiological conditions (square-pulse voltage clamp, slow pacing rates, exogenous Ca2+ buffers). METHODS We measured the major inward currents and their Ca2+- and β-adrenergic dependence under physiological AP clamp in rabbit ventricular myocytes in chronic pressure/volume overload-induced HF (versus age-matched control). RESULTS AP duration and short-term variability of AP repolarization were increased in HF, and importantly, inhibition of INaL decreased both parameters to the control level. INaL was slightly increased in HF versus control even when intracellular Ca2+ was strongly buffered. But under physiological AP clamp with normal Ca2+ cycling, INaL was markedly upregulated in HF versus control (dependent largely on CaMKII [Ca2+/calmodulin-dependent protein kinase II] activity). β-Adrenergic stimulation (often elevated in HF) further enhanced INaL. L-type Ca2+ current was decreased in HF when Ca2+ was buffered, but CaMKII-mediated Ca2+-dependent facilitation upregulated physiological L-type Ca2+ current to the control level. Furthermore, L-type Ca2+ current response to β-adrenergic stimulation was significantly attenuated in HF. Inward NCX current was upregulated at phase 3 of AP in HF when assessed by combining experimental data and computational modeling. CONCLUSIONS Our results suggest that CaMKII-dependent upregulation of INaL in HF significantly contributes to AP prolongation and increased short-term variability of AP repolarization, which may lead to increased arrhythmia propensity, and is further exacerbated by adrenergic stress.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis
| | | | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis
| | | | - Leighton T. Izu
- Department of Pharmacology, University of California Davis, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California Davis, Davis
- Department of Biomedical Engineering, University of California Davis, Davis
- Department of Internal Medicine/Cardiology, University of California Davis, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California Davis, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis
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7
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Oyamada J, Shimizu C, Kim J, Williams MR, Png E, Hibberd ML, Tremoulet AH, Perry JC, Burns JC. Bifid T waves on the ECG and genetic variation in calcium channel voltage-dependent beta 2 subunit gene (CACNB2) in acute Kawasaki disease. CONGENIT HEART DIS 2018; 14:213-220. [PMID: 30395415 DOI: 10.1111/chd.12696] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/07/2018] [Accepted: 10/09/2018] [Indexed: 01/11/2023]
Abstract
BACKGROUND We previously described the association of genetic variants in calcium channel genes and susceptibility to Kawasaki disease (KD), an acute, self-limited vasculitis, and the most common cause of acquired cardiac disease in children. Abnormal repolarization of cardiomyocytes and changes in T wave morphology have been reported in KD but have not been studied systematically. METHODS We analyzed acute and convalescent ECG T wave morphology in two independent cohorts of KD subjects and studied the association between bifid T waves and genetic variants in previously reported genes with SNVs associated with cardiac repolarization. RESULTS Bifid T waves in limb leads were identified in 24% and 27% of two independent cohorts of acute KD subjects. Calcium channel voltage-dependent beta 2 subunit gene (CACNB2) (rs1409207) showed association with bifid T waves in both cohorts (nominal P = .04 and P = .0003, respectively). This CACNB2 polymorphism also showed association with KD susceptibility in a previously published KD genome wide association study data (nominal P = .009). CONCLUSION This genotype/phenotype association study uncovered a variant in CACNB2 that may be associated with both KD susceptibility and bifid T waves, a novel signature of altered myocardial repolarization. The present study combined with published reports suggests that genetic variants in calcium channels and intracellular calcium signaling play a prominent role in shaping susceptibility to KD.
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Affiliation(s)
- Jun Oyamada
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California
| | - Chisato Shimizu
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California
| | - Jihoon Kim
- Division of Biomedical Informatics, Department of Medicine, University of San Diego, La Jolla, California
| | - Matthew R Williams
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California.,Rady Children's Hospital San Diego, San Diego, California
| | - Eileen Png
- Genome Institute of Singapore, Singapore
| | | | - Adriana H Tremoulet
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California.,Rady Children's Hospital San Diego, San Diego, California
| | - James C Perry
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California.,Rady Children's Hospital San Diego, San Diego, California
| | - Jane C Burns
- Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California.,Rady Children's Hospital San Diego, San Diego, California
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8
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Tanaka S, Fujio Y, Nakayama H. Caveolae-Specific CaMKII Signaling in the Regulation of Voltage-Dependent Calcium Channel and Cardiac Hypertrophy. Front Physiol 2018; 9:1081. [PMID: 30131723 PMCID: PMC6090180 DOI: 10.3389/fphys.2018.01081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/19/2018] [Indexed: 02/04/2023] Open
Abstract
Cardiac hypertrophy is a major risk for the progression of heart failure; however, the underlying molecular mechanisms contributing to this process remain elusive. The caveolae microdomain plays pivotal roles in various cellular processes such as lipid homeostasis, signal transduction, and endocytosis, and also serves as a signaling platform. Although the caveolae microdomain has been postulated to have a major contribution to the development of cardiac pathologies, including cardiac hypertrophy, recent evidence has placed this role into question. Lack of direct evidence and appropriate methods for determining activation of caveolae-specific signaling has thus far limited the ability to obtain a definite answer to the question. In this review, we focus on the potential physiological and pathological roles of the multifunctional kinase Ca2+/calmodulin-dependent kinase II and voltage-dependent L-type calcium channel in the caveolae, toward gaining a better understanding of the contribution of caveolae-based signaling in cardiac hypertrophy.
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Affiliation(s)
- Shota Tanaka
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Yasushi Fujio
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Hiroyuki Nakayama
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
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9
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Kumari N, Gaur H, Bhargava A. Cardiac voltage gated calcium channels and their regulation by β-adrenergic signaling. Life Sci 2017; 194:139-149. [PMID: 29288765 DOI: 10.1016/j.lfs.2017.12.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/17/2017] [Accepted: 12/24/2017] [Indexed: 01/08/2023]
Abstract
Voltage-gated calcium channels (VGCCs) are the predominant source of calcium influx in the heart leading to calcium-induced calcium release and ultimately excitation-contraction coupling. In the heart, VGCCs are modulated by the β-adrenergic signaling. Signaling through β-adrenergic receptors (βARs) and modulation of VGCCs by β-adrenergic signaling in the heart are critical signaling and changes to these have been significantly implicated in heart failure. However, data related to calcium channel dysfunction in heart failure is divergent and contradictory ranging from reduced function to no change in the calcium current. Many recent studies have highlighted the importance of functional and spatial microdomains in the heart and that may be the key to answer several puzzling questions. In this review, we have briefly discussed the types of VGCCs found in heart tissues, their structure, and significance in the normal and pathological condition of the heart. More importantly, we have reviewed the modulation of VGCCs by βARs in normal and pathological conditions incorporating functional and structural aspects. There are different types of βARs, each having their own significance in the functioning of the heart. Finally, we emphasize the importance of location of proteins as it relates to their function and modulation by co-signaling molecules. Its implication on the studies of heart failure is speculated.
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Affiliation(s)
- Neema Kumari
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India
| | - Himanshu Gaur
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India
| | - Anamika Bhargava
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India.
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10
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Exclusion of alternative exon 33 of Ca V1.2 calcium channels in heart is proarrhythmogenic. Proc Natl Acad Sci U S A 2017; 114:E4288-E4295. [PMID: 28490495 DOI: 10.1073/pnas.1617205114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Alternative splicing changes the CaV1.2 calcium channel electrophysiological property, but the in vivo significance of such altered channel function is lacking. Structure-function studies of heterologously expressed CaV1.2 channels could not recapitulate channel function in the native milieu of the cardiomyocyte. To address this gap in knowledge, we investigated the role of alternative exon 33 of the CaV1.2 calcium channel in heart function. Exclusion of exon 33 in CaV1.2 channels has been reported to shift the activation potential -10.4 mV to the hyperpolarized direction, and increased expression of CaV1.2Δ33 channels was observed in rat myocardial infarcted hearts. However, how a change in CaV1.2 channel electrophysiological property, due to alternative splicing, might affect cardiac function in vivo is unknown. To address these questions, we generated mCacna1c exon 33-/--null mice. These mice contained CaV1.2Δ33 channels with a gain-of-function that included conduction of larger currents that reflects a shift in voltage dependence and a modest increase in single-channel open probability. This altered channel property underscored the development of ventricular arrhythmia, which is reflected in significantly more deaths of exon 33-/- mice from β-adrenergic stimulation. In vivo telemetric recordings also confirmed increased frequencies in premature ventricular contractions, tachycardia, and lengthened QT interval. Taken together, the significant decrease or absence of exon 33-containing CaV1.2 channels is potentially proarrhythmic in the heart. Of clinical relevance, human ischemic and dilated cardiomyopathy hearts showed increased inclusion of exon 33. However, the possible role that inclusion of exon 33 in CaV1.2 channels may play in the pathogenesis of human heart failure remains unclear.
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11
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Tonegawa K, Otsuka W, Kumagai S, Matsunami S, Hayamizu N, Tanaka S, Moriwaki K, Obana M, Maeda M, Asahi M, Kiyonari H, Fujio Y, Nakayama H. Caveolae-specific activation loop between CaMKII and L-type Ca 2+ channel aggravates cardiac hypertrophy in α 1-adrenergic stimulation. Am J Physiol Heart Circ Physiol 2016; 312:H501-H514. [PMID: 28039202 DOI: 10.1152/ajpheart.00601.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/01/2016] [Accepted: 11/15/2016] [Indexed: 11/22/2022]
Abstract
Activation of CaMKII induces a myriad of biological processes and plays dominant roles in cardiac hypertrophy. Caveolar microdomain contains many calcium/calmodulin-dependent kinase II (CaMKII) targets, including L-type Ca2+ channel (LTCC) complex, and serves as a signaling platform. The location of CaMKII activation is thought to be critical; however, the roles of CaMKII in caveolae are still elusive due to lack of methodology for the assessment of caveolae-specific activation. Our aim was to develop a novel tool for the specific analysis of CaMKII activation in caveolae and to determine the functional role of caveolar CaMKII in cardiac hypertrophy. To assess the caveolae-specific activation of CaMKII, we generated a fusion protein composed of phospholamban and caveolin-3 (cPLN-Cav3) and GFP fusion protein with caveolin-binding domain fused to CaMKII inhibitory peptide (CBD-GFP-AIP), which inhibits CaMKII activation specifically in caveolae. Caveolae-specific activation of CaMKII was detected using phosphospecific antibody for PLN (Thr17). Furthermore, adenoviral overexpression of LTCC β2a-subunit (β2a) in NRCMs showed its constitutive phosphorylation by CaMKII, which induces hypertrophy, and that both phosphorylation and hypertrophy are abolished by CBD-GFP-AIP expression, indicating that β2a phosphorylation occurs specifically in caveolae. Finally, β2a phosphorylation was observed after phenylephrine stimulation in β2a-overexpressing mice, and attenuation of cardiac hypertrophy after chronic phenylephrine stimulation was observed in nonphosphorylated mutant of β2a-overexpressing mice. We developed novel tools for the evaluation and inhibition of caveolae-specific activation of CaMKII. We demonstrated that phosphorylated β2a dominantly localizes to caveolae and induces cardiac hypertrophy after α1-adrenergic stimulation in mice.NEW & NOTEWORTHY While signaling in caveolae is thought to be important in cardiac hypertrophy, direct evidence is missing due to lack of tools to assess caveolae-specific signaling. This is the first study to demonstrate caveolae-specific activation of CaMKII signaling in cardiac hypertrophy induced by α1-adrenergic stimulation using an originally developed tool.
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Affiliation(s)
- Kota Tonegawa
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Wataru Otsuka
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Shohei Kumagai
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Sachi Matsunami
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Nao Hayamizu
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Shota Tanaka
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Kazumasa Moriwaki
- Faculty of Medicine, Department of Pharmacology, Osaka Medical College, Takatsuki, Osaka, Japan; and
| | - Masanori Obana
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Makiko Maeda
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Michio Asahi
- Faculty of Medicine, Department of Pharmacology, Osaka Medical College, Takatsuki, Osaka, Japan; and
| | - Hiroshi Kiyonari
- Animal Resource Development Unit and Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan
| | - Yasushi Fujio
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Hiroyuki Nakayama
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan;
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Sanchez-Alonso JL, Bhargava A, O'Hara T, Glukhov AV, Schobesberger S, Bhogal N, Sikkel MB, Mansfield C, Korchev YE, Lyon AR, Punjabi PP, Nikolaev VO, Trayanova NA, Gorelik J. Microdomain-Specific Modulation of L-Type Calcium Channels Leads to Triggered Ventricular Arrhythmia in Heart Failure. Circ Res 2016; 119:944-55. [PMID: 27572487 PMCID: PMC5045818 DOI: 10.1161/circresaha.116.308698] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 08/24/2016] [Indexed: 11/22/2022]
Abstract
Supplemental Digital Content is available in the text. Rationale: Disruption in subcellular targeting of Ca2+ signaling complexes secondary to changes in cardiac myocyte structure may contribute to the pathophysiology of a variety of cardiac diseases, including heart failure (HF) and certain arrhythmias. Objective: To explore microdomain-targeted remodeling of ventricular L-type Ca2+ channels (LTCCs) in HF. Methods and Results: Super-resolution scanning patch-clamp, confocal and fluorescence microscopy were used to explore the distribution of single LTCCs in different membrane microdomains of nonfailing and failing human and rat ventricular myocytes. Disruption of membrane structure in both species led to the redistribution of functional LTCCs from their canonical location in transversal tubules (T-tubules) to the non-native crest of the sarcolemma, where their open probability was dramatically increased (0.034±0.011 versus 0.154±0.027, P<0.001). High open probability was linked to enhance calcium–calmodulin kinase II–mediated phosphorylation in non-native microdomains and resulted in an elevated ICa,L window current, which contributed to the development of early afterdepolarizations. A novel model of LTCC function in HF was developed; after its validation with experimental data, the model was used to ascertain how HF-induced T-tubule loss led to altered LTCC function and early afterdepolarizations. The HF myocyte model was then implemented in a 3-dimensional left ventricle model, demonstrating that such early afterdepolarizations can propagate and initiate reentrant arrhythmias. Conclusions: Microdomain-targeted remodeling of LTCC properties is an important event in pathways that may contribute to ventricular arrhythmogenesis in the settings of HF-associated remodeling. This extends beyond the classical concept of electric remodeling in HF and adds a new dimension to cardiovascular disease.
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Affiliation(s)
- Jose L Sanchez-Alonso
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Anamika Bhargava
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Thomas O'Hara
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Alexey V Glukhov
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Sophie Schobesberger
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Navneet Bhogal
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Markus B Sikkel
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Catherine Mansfield
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Yuri E Korchev
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Alexander R Lyon
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Prakash P Punjabi
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Viacheslav O Nikolaev
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Natalia A Trayanova
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.)
| | - Julia Gorelik
- From the Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute (J.L.S.-A., A.B., A.V.G., S.S., N.B., M.B.S., C.M., A.R.L., P.P.P., J.G.), Department of Medicine (Y.E.K.), and Department of Cardiothoracic Surgery, Hammersmith Hospital, National Heart and Lung Institute (P.P.P.), Imperial College London, United Kingdom; Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD (T.O., N.A.T.); NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom (A.R.L.); Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (S.S., V.O.N.); and Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, India (A.B.).
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Rusconi F, Ceriotti P, Miragoli M, Carullo P, Salvarani N, Rocchetti M, Di Pasquale E, Rossi S, Tessari M, Caprari S, Cazade M, Kunderfranco P, Chemin J, Bang ML, Polticelli F, Zaza A, Faggian G, Condorelli G, Catalucci D. Peptidomimetic Targeting of Cavβ2 Overcomes Dysregulation of the L-Type Calcium Channel Density and Recovers Cardiac Function. Circulation 2016; 134:534-46. [PMID: 27486162 DOI: 10.1161/circulationaha.116.021347] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 06/27/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND L-type calcium channels (LTCCs) play important roles in regulating cardiomyocyte physiology, which is governed by appropriate LTCC trafficking to and density at the cell surface. Factors influencing the expression, half-life, subcellular trafficking, and gating of LTCCs are therefore critically involved in conditions of cardiac physiology and disease. METHODS Yeast 2-hybrid screenings, biochemical and molecular evaluations, protein interaction assays, fluorescence microscopy, structural molecular modeling, and functional studies were used to investigate the molecular mechanisms through which the LTCC Cavβ2 chaperone regulates channel density at the plasma membrane. RESULTS On the basis of our previous results, we found a direct linear correlation between the total amount of the LTCC pore-forming Cavα1.2 and the Akt-dependent phosphorylation status of Cavβ2 both in a mouse model of diabetic cardiac disease and in 6 diabetic and 7 nondiabetic cardiomyopathy patients with aortic stenosis undergoing aortic valve replacement. Mechanistically, we demonstrate that a conformational change in Cavβ2 triggered by Akt phosphorylation increases LTCC density at the cardiac plasma membrane, and thus the inward calcium current, through a complex pathway involving reduction of Cavα1.2 retrograde trafficking and protein degradation through the prevention of dynamin-mediated LTCC endocytosis; promotion of Cavα1.2 anterograde trafficking by blocking Kir/Gem-dependent sequestration of Cavβ2, thus facilitating the chaperoning of Cavα1.2; and promotion of Cavα1.2 transcription by the prevention of Kir/Gem-mediated shuttling of Cavβ2 to the nucleus, where it limits the transcription of Cavα1.2 through recruitment of the heterochromatin protein 1γ epigenetic repressor to the Cacna1c promoter. On the basis of this mechanism, we developed a novel mimetic peptide that, through targeting of Cavβ2, corrects LTCC life-cycle alterations, facilitating the proper function of cardiac cells. Delivery of mimetic peptide into a mouse model of diabetic cardiac disease associated with LTCC abnormalities restored impaired calcium balance and recovered cardiac function. CONCLUSIONS We have uncovered novel mechanisms modulating LTCC trafficking and life cycle and provide proof of concept for the use of Cavβ2 mimetic peptide as a novel therapeutic tool for the improvement of cardiac conditions correlated with alterations in LTCC levels and function.
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Affiliation(s)
- Francesca Rusconi
- From Humanitas Clinical and Research Center, Rozzano, Milan, Italy (F.R., P. Ceriotti, M.M., P. Carullo, N.S., E.D.P., P.K., M.-L.B., G.C., D.C.); Institute of Genetic and Biomedical Research UOS Milan National Research Council, Milan, Italy (F.R., P. Carullo, N.S., E.D.P., M.-L.B., D.C.); Department of Biotechnologies and Biosciences, University of Milan-Bicocca, Milan, Italy (M.R., A.Z.); Departments of Life Sciences (S.R.) and Clinical and Experimental Medicine (M.M.), University of Parma, Parma, Italy; University Hospital of Verona, Division of Cardiac Surgery, Verona, Italy (M.T., G.F.); Department of Sciences, University of Roma Tre, Rome, Italy (S.C., F.P.); University of Montpellier, CNRS UMR 5203, INSERM, Department of Neuroscience, Institute for Functional Genomics, LabEx Ion Channel Science and Therapeutics, Montpellier, France (M.C., J.C.); and National Institute of Nuclear Physics, Rome Tre Section, Rome, Italy (F.P.)
| | - Paola Ceriotti
- From Humanitas Clinical and Research Center, Rozzano, Milan, Italy (F.R., P. Ceriotti, M.M., P. Carullo, N.S., E.D.P., P.K., M.-L.B., G.C., D.C.); Institute of Genetic and Biomedical Research UOS Milan National Research Council, Milan, Italy (F.R., P. Carullo, N.S., E.D.P., M.-L.B., D.C.); Department of Biotechnologies and Biosciences, University of Milan-Bicocca, Milan, Italy (M.R., A.Z.); Departments of Life Sciences (S.R.) and Clinical and Experimental Medicine (M.M.), University of Parma, Parma, Italy; University Hospital of Verona, Division of Cardiac Surgery, Verona, Italy (M.T., G.F.); Department of Sciences, University of Roma Tre, Rome, Italy (S.C., F.P.); University of Montpellier, CNRS UMR 5203, INSERM, Department of Neuroscience, Institute for Functional Genomics, LabEx Ion Channel Science and Therapeutics, Montpellier, France (M.C., J.C.); and National Institute of Nuclear Physics, Rome Tre Section, Rome, Italy (F.P.)
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14
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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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15
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Balycheva M, Faggian G, Glukhov AV, Gorelik J. Microdomain-specific localization of functional ion channels in cardiomyocytes: an emerging concept of local regulation and remodelling. Biophys Rev 2015; 7:43-62. [PMID: 28509981 PMCID: PMC5425752 DOI: 10.1007/s12551-014-0159-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/18/2014] [Indexed: 12/26/2022] Open
Abstract
Cardiac excitation involves the generation of action potential by individual cells and the subsequent conduction of the action potential from cell to cell through intercellular gap junctions. Excitation of the cellular membrane results in opening of the voltage-gated L-type calcium ion (Ca2+) channels, thereby allowing a small amount of Ca2+ to enter the cell, which in turn triggers the release of a much greater amount of Ca2+ from the sarcoplasmic reticulum, the intracellular Ca2+ store, and gives rise to the systolic Ca2+ transient and contraction. These processes are highly regulated by the autonomic nervous system, which ensures the acute and reliable contractile function of the heart and the short-term modulation of this function upon changes in heart rate or workload. It has recently become evident that discrete clusters of different ion channels and regulatory receptors are present in the sarcolemma, where they form an interacting network and work together as a part of a macro-molecular signalling complex which in turn allows the specificity, reliability and accuracy of the autonomic modulation of the excitation-contraction processes by a variety of neurohormonal pathways. Disruption in subcellular targeting of ion channels and associated signalling proteins may contribute to the pathophysiology of a variety of cardiac diseases, including heart failure and certain arrhythmias. Recent methodological advances have made it possible to routinely image the topography of live cardiomyocytes, allowing the study of clustering functional ion channels and receptors as well as their coupling within a specific microdomain. In this review we highlight the emerging understanding of the functionality of distinct subcellular microdomains in cardiac myocytes (e.g. T-tubules, lipid rafts/caveolae, costameres and intercalated discs) and their functional role in the accumulation and regulation of different subcellular populations of sodium, Ca2+ and potassium ion channels and their contributions to cellular signalling and cardiac pathology.
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Affiliation(s)
- Marina Balycheva
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Giuseppe Faggian
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Alexey V Glukhov
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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16
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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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17
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Viola HM, Jordan MC, Roos KP, Hool LC. Decreased myocardial injury and improved contractility after administration of a peptide derived against the alpha-interacting domain of the L-type calcium channel. J Am Heart Assoc 2014; 3:e000961. [PMID: 24958783 PMCID: PMC4309103 DOI: 10.1161/jaha.114.000961] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Background Myocardial infarction remains the leading cause of morbidity and mortality associated with coronary artery disease. The L‐type calcium channel (ICa‐L) is critical to excitation and contraction. Activation of the channel also alters mitochondrial function. Here, we investigated whether application of a alpha‐interacting domain/transactivator of transcription (AID‐TAT) peptide, which immobilizes the auxiliary β2 subunit of the channel and decreases metabolic demand, could alter mitochondrial function and myocardial injury. Methods and Results Treatment with AID‐TAT peptide decreased ischemia‐reperfusion injury in guinea‐pig hearts ex vivo (n=11) and in rats in vivo (n=9) assessed with uptake of nitroblue tetrazolium, release of creatine kinase, and lactate dehydrogenase. Contractility (assessed with catheterization of the left ventricle) was improved after application of AID‐TAT peptide in hearts ex vivo (n=6) and in vivo (n=8) up to 12 weeks before sacrifice. In search of the mechanism for the effect, we found that intracellular calcium ([Ca2+]i, Fura‐2), superoxide production (dihydroethidium fluorescence), mitochondrial membrane potential (Ψm, JC‐1 fluorescence), reduced nicotinamide adenine dinucleotide production, and flavoprotein oxidation (autofluorescence) are decreased after application of AID‐TAT peptide. Conclusions Application of AID‐TAT peptide significantly decreased infarct size and supported contractility up to 12 weeks postcoronary artery occlusion as a result of a decrease in metabolic demand during reperfusion.
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Affiliation(s)
- Helena M Viola
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia (H.M.V., L.C.H.)
| | - Maria C Jordan
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (M.C.J., K.P.R.)
| | - Kenneth P Roos
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (M.C.J., K.P.R.)
| | - Livia C Hool
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia (H.M.V., L.C.H.)
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18
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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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19
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Vincent KP, McCulloch AD, Edwards AG. Toward a hierarchy of mechanisms in CaMKII-mediated arrhythmia. Front Pharmacol 2014; 5:110. [PMID: 24994983 PMCID: PMC4062880 DOI: 10.3389/fphar.2014.00110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/25/2014] [Indexed: 12/16/2022] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) activity has been shown to contribute to arrhythmogenesis in a remarkably broad range of cardiac pathologies. Several of these involve significant structural and electrophysiologic remodeling, whereas others are due to specific channelopathies, and are not typically associated with arrhythmogenic changes to protein expression or cellular and tissue structure. The ability of CaMKII to contribute to arrhythmia across such a broad range of phenotypes suggests one of two interpretations regarding the role of CaMKII in cardiac arrhythmia: (1) some CaMKII-dependent mechanism is a common driver of arrhythmia irrespective of the specific etiology of the disease, or (2) these different etiologies expose different mechanisms by which CaMKII is capable of promoting arrhythmia. In this review, we dissect the available mechanistic evidence to explore these two possibilities and discuss how the various molecular actions of CaMKII promote arrhythmia in different pathophysiologic contexts.
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Affiliation(s)
- Kevin P Vincent
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA ; Department of Medicine, University of California San Diego La Jolla, CA, USA
| | - Andrew G Edwards
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA ; Institute for Experimental Medicine, Oslo University Hospital Ullevål Oslo, Norway ; Simula Research Laboratory Lysaker, Norway
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20
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Fischer TH, Neef S, Maier LS. The Ca-calmodulin dependent kinase II: A promising target for future antiarrhythmic therapies? J Mol Cell Cardiol 2013; 58:182-7. [DOI: 10.1016/j.yjmcc.2012.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 11/02/2012] [Accepted: 11/05/2012] [Indexed: 12/19/2022]
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21
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Nakayama H, Fujio Y. [Ca2+-mediated pathogenesis in the heart]. Nihon Yakurigaku Zasshi 2012; 140:270-274. [PMID: 23229633 DOI: 10.1254/fpj.140.270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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22
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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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23
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Single-channel monitoring of reversible L-type Ca(2+) channel Ca(V)α(1)-Ca(V)β subunit interaction. Biophys J 2012; 101:2661-70. [PMID: 22261054 DOI: 10.1016/j.bpj.2011.09.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/06/2011] [Indexed: 11/24/2022] Open
Abstract
Voltage-dependent Ca(2+) channels are heteromultimers of Ca(V)α(1) (pore), Ca(V)β- and Ca(V)α(2)δ-subunits. The stoichiometry of this complex, and whether it is dynamically regulated in intact cells, remains controversial. Fortunately, Ca(V)β-isoforms affect gating differentially, and we chose two extremes (Ca(V)β(1a) and Ca(V)β(2b)) regarding single-channel open probability to address this question. HEK293α(1C) cells expressing the Ca(V)1.2 subunit were transiently transfected with Ca(V)α(2)δ1 alone or with Ca(V)β(1a), Ca(V)β(2b), or (2:1 or 1:1 plasmid ratio) combinations. Both Ca(V)β-subunits increased whole-cell current and shifted the voltage dependence of activation and inactivation to hyperpolarization. Time-dependent inactivation was accelerated by Ca(V)β(1a)-subunits but not by Ca(V)β(2b)-subunits. Mixtures induced intermediate phenotypes. Single channels sometimes switched between periods of low and high open probability. To validate such slow gating behavior, data were segmented in clusters of statistically similar open probability. With Ca(V)β(1a)-subunits alone, channels mostly stayed in clusters (or regimes of alike clusters) of low open probability. Increasing Ca(V)β(2b)-subunits (co-)expressed (1:2, 1:1 ratio or alone) progressively enhanced the frequency and total duration of high open probability clusters and regimes. Our analysis was validated by the inactivation behavior of segmented ensemble averages. Hence, a phenotype consistent with mutually exclusive and dynamically competing binding of different Ca(V)β-subunits is demonstrated in intact cells.
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24
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Vos MA, Sipido KR. Impairment of trafficking by downregulation of an anchor protein: novel insights into additional mechanisms responsible for heart failure. Heart Rhythm 2012; 9:821-2. [PMID: 22306101 DOI: 10.1016/j.hrthm.2012.01.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Indexed: 11/16/2022]
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Gαi2- and Gαi3-specific regulation of voltage-dependent L-type calcium channels in cardiomyocytes. PLoS One 2011; 6:e24979. [PMID: 21966394 PMCID: PMC3180279 DOI: 10.1371/journal.pone.0024979] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 08/23/2011] [Indexed: 11/19/2022] Open
Abstract
Background Two pertussis toxin sensitive Gi proteins, Gi2 and Gi3, are expressed in cardiomyocytes and upregulated in heart failure. It has been proposed that the highly homologous Gi isoforms are functionally distinct. To test for isoform-specific functions of Gi proteins, we examined their role in the regulation of cardiac L-type voltage-dependent calcium channels (L-VDCC). Methods Ventricular tissues and isolated myocytes were obtained from mice with targeted deletion of either Gαi2 (Gαi2−/−) or Gαi3 (Gαi3−/−). mRNA levels of Gαi/o isoforms and L-VDCC subunits were quantified by real-time PCR. Gαi and Cavα1 protein levels as well as protein kinase B/Akt and extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation levels were assessed by immunoblot analysis. L-VDCC function was assessed by whole-cell and single-channel current recordings. Results In cardiac tissue from Gαi2−/− mice, Gαi3 mRNA and protein expression was upregulated to 187±21% and 567±59%, respectively. In Gαi3−/− mouse hearts, Gαi2 mRNA (127±5%) and protein (131±10%) levels were slightly enhanced. Interestingly, L-VDCC current density in cardiomyocytes from Gαi2−/− mice was lowered (−7.9±0.6 pA/pF, n = 11, p<0.05) compared to wild-type cells (−10.7±0.5 pA/pF, n = 22), whereas it was increased in myocytes from Gαi3−/− mice (−14.3±0.8 pA/pF, n = 14, p<0.05). Steady-state inactivation was shifted to negative potentials, and recovery kinetics slowed in the absence of Gαi2 (but not of Gαi3) and following treatment with pertussis toxin in Gαi3−/−. The pore forming Cavα1 protein level was unchanged in all mouse models analyzed, similar to mRNA levels of Cavα1 and Cavβ2 subunits. Interestingly, at the cellular signalling level, phosphorylation assays revealed abolished carbachol-triggered activation of ERK1/2 in mice lacking Gαi2. Conclusion Our data provide novel evidence for an isoform-specific modulation of L-VDCC by Gαi proteins. In particular, loss of Gαi2 is reflected by alterations in channel kinetics and likely involves an impairment of the ERK1/2 signalling pathway.
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Miranda-Laferte E, Gonzalez-Gutierrez G, Schmidt S, Zeug A, Ponimaskin EG, Neely A, Hidalgo P. Homodimerization of the Src homology 3 domain of the calcium channel β-subunit drives dynamin-dependent endocytosis. J Biol Chem 2011; 286:22203-10. [PMID: 21502319 DOI: 10.1074/jbc.m110.201871] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Voltage-dependent calcium channels constitute the main entry pathway for calcium into excitable cells. They are heteromultimers formed by an α(1) pore-forming subunit (Ca(V)α(1)) and accessory subunits. To achieve a precise coordination of calcium signals, the expression and activity of these channels is tightly controlled. The accessory β-subunit (Ca(V)β), a membrane associated guanylate kinase containing one guanylate kinase (β-GK) and one Src homology 3 (β-SH3) domain, has antagonistic effects on calcium currents by regulating different aspects of channel function. Although β-GK binds to a conserved site within the α(1)-pore-forming subunit and facilitates channel opening, β-SH3 binds to dynamin and promotes endocytosis. Here, we investigated the molecular switch underlying the functional duality of this modular protein. We show that β-SH3 homodimerizes through a single disulfide bond. Substitution of the only cysteine residue abolishes dimerization and impairs internalization of L-type Ca(V)1.2 channels expressed in Xenopus oocytes while preserving dynamin binding. Covalent linkage of the β-SH3 dimerization-deficient mutant yields a concatamer that binds to dynamin and restores endocytosis. Moreover, using FRET analysis, we show in living cells that Ca(V)β form oligomers and that this interaction is reduced by Ca(V)α(1). Association of Ca(V)β with a polypeptide encoding the binding motif in Ca(V)α(1) inhibited endocytosis. Together, these findings reveal that β-SH3 dimerization is crucial for endocytosis and suggest that channel activation and internalization are two mutually exclusive functions of Ca(V)β. We propose that a change in the oligomeric state of Ca(V)β is the functional switch between channel activator and channel internalizer.
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Affiliation(s)
- Erick Miranda-Laferte
- Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
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27
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Altier C, Garcia-Caballero A, Simms B, You H, Chen L, Walcher J, Tedford HW, Hermosilla T, Zamponi GW. The Cavβ subunit prevents RFP2-mediated ubiquitination and proteasomal degradation of L-type channels. Nat Neurosci 2010; 14:173-80. [PMID: 21186355 DOI: 10.1038/nn.2712] [Citation(s) in RCA: 191] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 11/12/2010] [Indexed: 01/19/2023]
Abstract
It is well established that the auxiliary Cavβ subunit regulates calcium channel density in the plasma membrane, but the cellular mechanism by which this occurs has remained unclear. We found that the Cavβ subunit increased membrane expression of Cav1.2 channels by preventing the entry of the channels into the endoplasmic reticulum-associated protein degradation (ERAD) complex. Without Cavβ, Cav1.2 channels underwent robust ubiquitination by the RFP2 ubiquitin ligase and interacted with the ERAD complex proteins derlin-1 and p97, culminating in targeting of the channels to the proteasome for degradation. On treatment with the proteasomal inhibitor MG132, Cavβ-free channels were rescued from degradation and trafficked to the plasma membrane. The coexpression of Cavβ interfered with ubiquitination and targeting of the channel to the ERAD complex, thereby facilitating export from the endoplasmic reticulum and promoting expression on the cell surface. Thus, Cavββ regulates the ubiquitination and stability of the calcium channel complex.
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Affiliation(s)
- Christophe Altier
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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28
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Lao QZ, Kobrinsky E, Liu Z, Soldatov NM. Oligomerization of Ca vβ subunits is an essential correlate of Ca 2+channel activity. FASEB J 2010. [DOI: 10.1096/fj.10.165381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Qi Zong Lao
- National Institute on Aging, National Institutes of Health Baltimore Maryland USA
| | - Evgeny Kobrinsky
- National Institute on Aging, National Institutes of Health Baltimore Maryland USA
| | - Zhuo Liu
- National Institute on Aging, National Institutes of Health Baltimore Maryland USA
| | - Nikolai M. Soldatov
- National Institute on Aging, National Institutes of Health Baltimore Maryland USA
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Chen X, Nakayama H, Zhang X, Ai X, Harris DM, Tang M, Zhang H, Szeto C, Stockbower K, Berretta RM, Eckhart AD, Koch WJ, Molkentin JD, Houser SR. Calcium influx through Cav1.2 is a proximal signal for pathological cardiomyocyte hypertrophy. J Mol Cell Cardiol 2010; 50:460-70. [PMID: 21111744 DOI: 10.1016/j.yjmcc.2010.11.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 10/21/2010] [Accepted: 11/11/2010] [Indexed: 01/20/2023]
Abstract
Pathological cardiac hypertrophy (PCH) is associated with the development of arrhythmia and congestive heart failure. While calcium (Ca(2+)) is implicated in hypertrophic signaling pathways, the specific role of Ca(2+) influx through the L-type Ca(2+) channel (I(Ca-L)) has been controversial and is the topic of this study. To determine if and how sustained increases in I(Ca-L) induce PCH, transgenic mouse models with low (LE) and high (HE) expression levels of the β2a subunit of Ca(2+) channels (β2a) and in cultured adult feline (AF) and neonatal rat (NR) ventricular myocytes (VMs) infected with an adenovirus containing a β2a-GFP were used. In vivo, β2a LE and HE mice had increased heart weight to body weight ratio, posterior wall and interventricular septal thickness, tissue fibrosis, myocyte volume, and cross-sectional area and the expression of PCH markers in a time- and dose-dependent manner. PCH was associated with a hypercontractile phenotype including enhanced I(Ca-L), fractional shortening, peak Ca(2+) transient, at the myocyte level, greater ejection fraction, and fractional shortening at the organ level. In addition, LE mice had an exaggerated hypertrophic response to transverse aortic constriction. In vitro overexpression of β2a in cultured AFVMs increased I(Ca-L), cell volume, protein synthesis, NFAT, and HDAC translocations and in NRVMs increased surface area. These effects were abolished by the blockade of I(Ca-L), intracellular Ca(2+), calcineurin, CaMKII, and SERCA. In conclusion, increasing I(Ca-L) is sufficient to induce PCH through the calcineurin/NFAT and CaMKII/HDAC pathways. Both cytosolic and SR/ER-nuclear envelop Ca(2+) pools were shown to be involved.
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Affiliation(s)
- Xiongwen Chen
- Cardiovascular Research Center and Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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Heinzel FR, MacQuaide N, Biesmans L, Sipido K. Dyssynchrony of Ca2+ release from the sarcoplasmic reticulum as subcellular mechanism of cardiac contractile dysfunction. J Mol Cell Cardiol 2010; 50:390-400. [PMID: 21075114 DOI: 10.1016/j.yjmcc.2010.11.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 09/30/2010] [Accepted: 11/05/2010] [Indexed: 02/05/2023]
Abstract
Cardiac contractile function depends on coordinated electrical activation throughout the heart. Dyssynchronous electrical activation of the ventricles has been shown to contribute to contractile dysfunction in heart failure, and resynchronization therapy has emerged as a therapeutic concept. At the cellular level, coupling of membrane excitation to myofilament contraction is facilitated by highly organized intracellular structures which coordinate Ca(2+) release. The cytosolic [Ca(2+)] transient triggered by depolarization-induced Ca(2+) influx is the result of a gradable and robust high gain process, Ca(2+)-induced Ca(2+) release (CICR), which integrates subcellular localized Ca(2+) release events. Lack of synchronization of these localized release events can contribute to contractile dysfunction in myocardial hypertrophy and heart failure. Different underlying mechanisms relate to functional and structural changes in sarcolemmal Ca(2+) channels, the sarcoplasmic Ca(2+) release channel or ryanodine receptor, RyR, their intracellular arrangement in close proximity in couplons and the loss of t-tubules. Dyssynchrony at the subcellular level translates in a reduction of the overall gain of CICR at the cellular level and forms an important determinant of myocyte contractility in heart failure.
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Lao QZ, Kobrinsky E, Liu Z, Soldatov NM. Oligomerization of Cavbeta subunits is an essential correlate of Ca2+ channel activity. FASEB J 2010; 24:5013-23. [PMID: 20732952 DOI: 10.1096/fj.10-165381] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Voltage-gated calcium channels conduct Ca(2+) ions in response to membrane depolarization. The resulting transient increase in cytoplasmic free calcium concentration is a critical trigger for the initiation of such vital responses as muscle contraction and transcription. L-type Ca(v)1.2 calcium channels are complexes of the pore-forming α(1C) subunit associated with cytosolic Ca(v)β subunits. All major Ca(v)βs share a highly homologous membrane associated guanylate kinase-like (MAGUK) domain that binds to α(1C) at the α-interaction domain (AID), a short motif in the linker between transmembrane repeats I and II. In this study we show that Ca(v)β subunits form multimolecular homo- and heterooligomeric complexes in human vascular smooth muscle cells expressing native calcium channels and in Cos7 cells expressing recombinant Ca(v)1.2 channel subunits. Ca(v)βs oligomerize at the α(1C) subunits residing in the plasma membrane and bind to the AID. However, Ca(v)β oligomerization occurs independently on the association with α(1C). Molecular structures responsible for Ca(v)β oligomerization reside in 3 regions of the guanylate kinase subdomain of MAGUK. An augmentation of Ca(v)β homooligomerization significantly increases the calcium current density, while heterooligomerization may also change the voltage-dependence and inactivation kinetics of the channel. Thus, oligomerization of Ca(v)β subunits represents a novel and essential aspect of calcium channel regulation.
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Affiliation(s)
- Qi Zong Lao
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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32
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Tang M, Zhang X, Li Y, Guan Y, Ai X, Szeto C, Nakayama H, Zhang H, Ge S, Molkentin JD, Houser SR, Chen X. Enhanced basal contractility but reduced excitation-contraction coupling efficiency and beta-adrenergic reserve of hearts with increased Cav1.2 activity. Am J Physiol Heart Circ Physiol 2010; 299:H519-28. [PMID: 20543081 DOI: 10.1152/ajpheart.00265.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac remodeling during heart failure development induces a significant increase in the activity of the L-type Ca(2+) channel (Cav1.2). However, the effects of enhanced Cav1.2 activity on myocyte excitation-contraction (E-C) coupling, cardiac contractility, and its regulation by the beta-adrenergic system are not clear. To recapitulate the increased Cav1.2 activity, a double transgenic (DTG) mouse model overexpressing the Cavbeta2a subunit in a cardiac-specific and inducible manner was established. We studied cardiac (in vivo) and myocyte (in vitro) contractility at baseline and upon beta-adrenergic stimulation. E-C coupling efficiency was evaluated in isolated myocytes as well. The following results were found: 1) in DTG myocytes, L-type Ca(2+) current (I(Ca,L)) density, myocyte fractional shortening (FS), peak Ca(2+) transients, and sarcoplasmic reticulum (SR) Ca(2+) content (caffeine-induced Ca(2+) transient peak) were significantly increased (by 100.8%, 48.8%, 49.8%, and 46.8%, respectively); and 2) cardiac contractility evaluated with echocardiography [ejection fraction (EF) and (FS)] and invasive intra-left ventricular pressure (maximum dP/dt and -dP/dt) measurements were significantly greater in DTG mice than in control mice. However, 1) the cardiac contractility (EF, FS, dP/dt, and -dP/dt)-enhancing effect of the beta-adrenergic agonist isoproterenol (2 microg/g body wt ip) was significantly reduced in DTG mice, which could be attributed to the loss of beta-adrenergic stimulation on contraction, Ca(2+) transients, I(Ca,L), and SR Ca(2+) content in DTG myocytes; and 2) E-C couplng efficiency was significantly lower in DTG myocytes. In conclusion, increasing Cav1.2 activity by promoting its high-activity mode enhances cardiac contractility but decreases E-C coupling efficiency and the adrenergic reserve of the heart.
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Affiliation(s)
- Mingxin Tang
- Cardiovascular Research Center and Dept. of Physiology, Temple Univ. School of Medicine, 3400 N. Broad St., Philadelphia, PA 19140, USA
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Schulman H, Anderson ME. Ca/Calmodulin-dependent Protein Kinase II in Heart Failure. ACTA ACUST UNITED AC 2010; 7:e117-e122. [PMID: 21503275 DOI: 10.1016/j.ddmec.2010.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Howard Schulman
- Allosteros Therapeutics, Inc., 1230 Bordeaux Drive, Sunnyvale, CA 94089-1202
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34
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CaV1.2 beta-subunit coordinates CaMKII-triggered cardiomyocyte death and afterdepolarizations. Proc Natl Acad Sci U S A 2010; 107:4996-5000. [PMID: 20194790 DOI: 10.1073/pnas.0913760107] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Excessive activation of calmodulin kinase II (CaMKII) causes arrhythmias and heart failure, but the cellular mechanisms for CaMKII-targeted proteins causing disordered cell membrane excitability and myocardial dysfunction remain uncertain. Failing human cardiomyocytes exhibit increased CaMKII and voltage-gated Ca(2+) channel (Ca(V)1.2) activity, and enhanced expression of a specific Ca(V)1.2 beta-subunit protein isoform (beta(2a)). We recently identified Ca(V)1.2 beta(2a) residues critical for CaMKII phosphorylation (Thr 498) and binding (Leu 493), suggesting the hypothesis that these amino acids are crucial for cardiomyopathic consequences of CaMKII signaling. Here we show WT beta(2a) expression causes cellular Ca(2+) overload, arrhythmia-triggering cell membrane potential oscillations called early afterdepolarizations (EADs), and premature death in paced adult rabbit ventricular myocytes. Prevention of intracellular Ca(2+) release by ryanodine or global cellular CaMKII inhibition reduced EADs and improved cell survival to control levels in WT beta(2a)-expressing ventricular myocytes. In contrast, expression of beta(2a) T498A or L493A mutants mimicked the protective effects of ryanodine or global cellular CaMKII inhibition by reducing Ca(2+) entry through Ca(V)1.2 and inhibiting EADs. Furthermore, Ca(V)1.2 currents recorded from cells overexpressing CaMKII phosphorylation- or binding-incompetent beta(2a) subunits were incapable of entering a CaMKII-dependent high-activity gating mode (mode 2), indicating that beta(2a) Thr 498 and Leu 493 are required for Ca(V)1.2 activation by CaMKII in native cells. These data show that CaMKII binding and phosphorylation sites on beta(2a) are concise but pivotal components of a molecular and biophysical and mechanism for EADs and impaired survival in adult cardiomyocytes.
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Rajan S, Jagatheesan G, Karam CN, Alves ML, Bodi I, Schwartz A, Bulcao CF, D'Souza KM, Akhter SA, Boivin GP, Dube DK, Petrashevskaya N, Herr AB, Hullin R, Liggett SB, Wolska BM, Solaro RJ, Wieczorek DF. Molecular and functional characterization of a novel cardiac-specific human tropomyosin isoform. Circulation 2010; 121:410-8. [PMID: 20065163 DOI: 10.1161/circulationaha.109.889725] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Tropomyosin (TM), an essential actin-binding protein, is central to the control of calcium-regulated striated muscle contraction. Although TPM1alpha (also called alpha-TM) is the predominant TM isoform in human hearts, the precise TM isoform composition remains unclear. METHODS AND RESULTS In this study, we quantified for the first time the levels of striated muscle TM isoforms in human heart, including a novel isoform called TPM1kappa. By developing a TPM1kappa-specific antibody, we found that the TPM1kappa protein is expressed and incorporated into organized myofibrils in hearts and that its level is increased in human dilated cardiomyopathy and heart failure. To investigate the role of TPM1kappa in sarcomeric function, we generated transgenic mice overexpressing cardiac-specific TPM1kappa. Incorporation of increased levels of TPM1kappa protein in myofilaments leads to dilated cardiomyopathy. Physiological alterations include decreased fractional shortening, systolic and diastolic dysfunction, and decreased myofilament calcium sensitivity with no change in maximum developed tension. Additional biophysical studies demonstrate less structural stability and weaker actin-binding affinity of TPM1kappa compared with TPM1alpha. CONCLUSIONS This functional analysis of TPM1kappa provides a possible mechanism for the consequences of the TM isoform switch observed in dilated cardiomyopathy and heart failure patients.
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Affiliation(s)
- Sudarsan Rajan
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati Medical Center, Cincinnati, OH 45267-0524, USA
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36
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Nakayama H, Bodi I, Correll RN, Chen X, Lorenz J, Houser SR, Robbins J, Schwartz A, Molkentin JD. alpha1G-dependent T-type Ca2+ current antagonizes cardiac hypertrophy through a NOS3-dependent mechanism in mice. J Clin Invest 2009; 119:3787-96. [PMID: 19920353 DOI: 10.1172/jci39724] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 09/23/2009] [Indexed: 12/21/2022] Open
Abstract
In noncontractile cells, increases in intracellular Ca2+ concentration serve as a second messenger to signal proliferation, differentiation, metabolism, motility, and cell death. Many of these Ca2+-dependent regulatory processes operate in cardiomyocytes, although it remains unclear how Ca2+ serves as a second messenger given the high Ca2+ concentrations that control contraction. T-type Ca2+ channels are reexpressed in adult ventricular myocytes during pathologic hypertrophy, although their physiologic function remains unknown. Here we generated cardiac-specific transgenic mice with inducible expression of alpha1G, which generates Cav3.1 current, to investigate whether this type of Ca2+ influx mechanism regulates the cardiac hypertrophic response. Unexpectedly, alpha1G transgenic mice showed no cardiac pathology despite large increases in Ca2+ influx, and they were even partially resistant to pressure overload-, isoproterenol-, and exercise-induced cardiac hypertrophy. Conversely, alpha1G-/- mice displayed enhanced hypertrophic responses following pressure overload or isoproterenol infusion. Enhanced hypertrophy and disease in alpha1G-/- mice was rescued with the alpha1G transgene, demonstrating a myocyte-autonomous requirement of alpha1G for protection. Mechanistically, alpha1G interacted with NOS3, which augmented cGMP-dependent protein kinase type I activity in alpha1G transgenic hearts after pressure overload. Further, the anti-hypertrophic effect of alpha1G overexpression was abrogated by a NOS3 inhibitor and by crossing the mice onto the Nos3-/- background. Thus, cardiac alpha1G reexpression and its associated pool of T-type Ca2+ antagonize cardiac hypertrophy through a NOS3-dependent signaling mechanism.
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Affiliation(s)
- Hiroyuki Nakayama
- Department of Pediatrics, University of Cincinnati, Division of Molecular Cardiovascular Biology, Howard Hughes Medical Institute, Children's Hospital Medical Center, Cincinnati, Ohio, USA
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37
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Inactivation of L-type calcium channels is determined by the length of the N terminus of mutant β1 subunits. Pflugers Arch 2009; 459:399-411. [DOI: 10.1007/s00424-009-0738-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 09/10/2009] [Accepted: 09/15/2009] [Indexed: 11/25/2022]
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38
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Link S, Meissner M, Held B, Beck A, Weissgerber P, Freichel M, Flockerzi V. Diversity and developmental expression of L-type calcium channel beta2 proteins and their influence on calcium current in murine heart. J Biol Chem 2009; 284:30129-37. [PMID: 19723630 DOI: 10.1074/jbc.m109.045583] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
By now, little is known on L-type calcium channel (LTCC) subunits expressed in mouse heart. We show that CaVbeta2 proteins are the major CaVbeta components of the LTCC in embryonic and adult mouse heart, but that in embryonic heart CaVbeta3 proteins are also detectable. At least two CaVbeta2 variants of approximately 68 and approximately 72 kDa are expressed. To identify the underlying CaVbeta2 variants, cDNA libraries were constructed from poly(A)(+) RNA isolated from hearts of 7-day-old and adult mice. Screening identified 60 independent CaVbeta2 cDNA clones coding for four types of CaVbeta2 proteins only differing in their 5' sequences. CaVbeta2-N1, -N4, and -N5 but not -N3 were identified in isolated cardiomyocytes by RT-PCR and were sufficient to reconstitute the CaVbeta2 protein pattern in vitro. Significant L-type Ca(2+) currents (I(Ca)) were recorded in HEK293 cells after co-expression of CaV1.2 and CaVbeta2. Current kinetics were determined by the type of CaVbeta2 protein, with the approximately 72-kDa CaVbeta2a-N1 shifting the activation of I(Ca) significantly to depolarizing potentials compared with the other CaVbeta2 variants. Inactivation of I(Ca) was accelerated by CaVbeta2a-N1 and -N4, which also lead to slower activation compared with CaVbeta2a-N3 and -N5. In summary, this study reveals the molecular LTCC composition in mouse heart and indicates that expression of various CaVbeta2 proteins may be used to adapt the properties of LTCCs to changing myocardial requirements during development and that CaVbeta2a-N1-induced changes of I(Ca) kinetics might be essential in embryonic heart.
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Affiliation(s)
- Sabine Link
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany.
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39
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Benitah JP, Alvarez JL, Gómez AM. L-type Ca(2+) current in ventricular cardiomyocytes. J Mol Cell Cardiol 2009; 48:26-36. [PMID: 19660468 DOI: 10.1016/j.yjmcc.2009.07.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/09/2009] [Accepted: 07/27/2009] [Indexed: 12/24/2022]
Abstract
L-type Ca(2+) channels are mediators of Ca(2+) influx and the regulatory events accompanying it and are pivotal in the function and dysfunction of ventricular cardiac myocytes. L-type Ca(2+) channels are located in sarcolemma, including the T-tubules facing the sarcoplasmic reticulum junction, and are activated by membrane depolarization, but intracellular Ca(2+)-dependent inactivation limits Ca(2+) influx during action potential. I(CaL) is important in heart function because it triggers excitation-contraction coupling, modulates action potential shape and is involved in cardiac arrhythmia. L-type Ca(2+) channels are multi-subunit complexes that interact with several molecules involved in their regulations, notably by beta-adrenergic signaling. The present review highlights some of the recent findings on L-type Ca(2+) channel function, regulation, and alteration in acquired pathologies such as cardiac hypertrophy, heart failure and diabetic cardiomyopathy, as well as in inherited arrhythmic cardiac diseases such as Timothy and Brugada syndromes.
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40
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Beetz N, Hein L, Meszaros J, Gilsbach R, Barreto F, Meissner M, Hoppe UC, Schwartz A, Herzig S, Matthes J. Transgenic simulation of human heart failure-like L-type Ca2+-channels: implications for fibrosis and heart rate in mice. Cardiovasc Res 2009; 84:396-406. [PMID: 19620129 DOI: 10.1093/cvr/cvp251] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Cardiac L-type Ca(2+)-currents show distinct alterations in chronic heart failure, including increased single-channel activity and blunted adrenergic stimulation, but minor changes of whole-cell currents. Expression of L-type Ca(2+)-channel beta(2)-subunits is enhanced in human failing hearts. In order to determine whether prolonged alteration of Ca(2+)-channel gating by beta(2)-subunits contributes to heart failure pathogenesis, we generated and characterized transgenic mice with cardiac overexpression of a beta(2a)-subunit or the pore Ca(v)1.2 or both, respectively. METHODS AND RESULTS Four weeks induction of cardiac-specific overexpression of rat beta(2a)-subunits shifted steady-state activation and inactivation of whole-cell currents towards more negative potentials, leading to increased Ca(2+)-current density at more negative test potentials. Activity of single Ca(2+)-channels was increased in myocytes isolated from beta(2a)-transgenic mice. Ca(2+)-current stimulation by 8-Br-cAMP and okadaic acid was blunted in beta(2a)-transgenic myocytes. In vivo investigation revealed hypotension and bradycardia upon Ca(v)1.2-transgene expression but not in mice only overexpressing beta(2a). Double-transgenics showed cardiac arrhythmia. Interstitial fibrosis was aggravated by the beta(2a)-transgene compared with Ca(v)1.2-transgene expression alone. Overt cardiac hypertrophy was not observed in any model. CONCLUSION Cardiac overexpression of a Ca(2+)-channel beta(2a)-subunit alone is sufficient to induce Ca(2+)-channel properties characteristic of chronic human heart failure. beta(2a)-overexpression by itself did not induce cardiac hypertrophy or contractile dysfunction, but aggravated the development of arrhythmia and fibrosis in Ca(v)1.2-transgenic mice.
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Affiliation(s)
- Nadine Beetz
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
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41
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Brandt MC, Endres-Becker J, Zagidullin N, Motloch LJ, Er F, Rottlaender D, Michels G, Herzig S, Hoppe UC. Effects of KCNE2 on HCN isoforms: distinct modulation of membrane expression and single channel properties. Am J Physiol Heart Circ Physiol 2009; 297:H355-63. [DOI: 10.1152/ajpheart.00154.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hyperpolarization-activated cation (HCN) channels give rise to an inward current with similar but not identical characteristics compared with the pacemaker current ( If), suggesting that HCN channel function is modulated by regulatory β-subunits in native tissue. KCNE2 has been proposed to serve as a β-subunit of HCN channels; however, available data remain contradictory. To further clarify this situation, we therefore analyzed the effect of KCNE2 on whole cell currents, single channel properties, and membrane protein expression of all cardiac HCN isoforms in the CHO cell system. On the whole cell level, current densities of all HCN isoforms were significantly increased by KCNE2 without altering voltage dependence or current reversal. While these results correlated well with the KCNE2-mediated 2.2-fold and 1.6-fold increases of membrane protein levels of HCN2 and HCN4, respectively, no effect of KCNE2 on HCN1 expression was obtained. All HCN subtypes displayed faster activation kinetics upon coexpression with KCNE2. Most importantly, for the first time, we demonstrated modulation of single channel function by KCNE2, thus supporting direct functional interaction with HCN subunits. In the presence of KCNE2, the single channel amplitudes and conductance of HCN1, HCN2, and HCN4 were significantly increased versus control recordings. Mean open time was significantly increased in cells coexpressing HCN2 + KCNE2, whereas it was unaffected in HCN1 + KCNE2 cotransfected cells and reduced in HCN4 + KCNE2 cotransfected cells compared with the respective HCN subunits alone. Thus, we demonstrate KCNE2-mediated distinct effects on HCN membrane expression and direct functional modulation of HCN isoforms, further supporting that KCNE2 surves as a regulatory β-subunit of HCN channels.
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Dilated cardiomyopathy with increased SR Ca2+ loading preceded by a hypercontractile state and diastolic failure in the alpha(1C)TG mouse. PLoS One 2009; 4:e4133. [PMID: 19125184 PMCID: PMC2607013 DOI: 10.1371/journal.pone.0004133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 11/20/2008] [Indexed: 11/19/2022] Open
Abstract
Mice over-expressing the alpha(1)_subunit (pore) of the L-type Ca2+ channel (alpha(1C)TG) by 4 months (mo) of age exhibit an enlarged heart, hypertrophied myocytes, increased Ca2+ current and Ca2+ transient amplitude, but a normal SR Ca2+ load. With advancing age (8-11 mo), some mice demonstrate advanced hypertrophy but are not in congestive heart failure (NFTG),while others evolve to frank dilated congestive heart failure (FTG). We demonstrate that older NFTG myocytes exhibit a hypercontractile state over a wide range of stimulation frequencies, but maintain a normal SR Ca2+ load compared to age matched non-transgenic (NTG) myocytes. However, at high stimulation rates (2-4 Hz) signs of diastolic contractile failure appear in NFTG cells. The evolution of frank congestive failure in FTG is accompanied by a further increase in heart mass and myocyte size, and phospholamban and ryanodine receptor protein levels and phosphorylation become reduced. In FTG, the SR Ca2+ load increases and Ca2+ release following excitation, increases further. An enhanced NCX function in FTG, as reflected by an accelerated relaxation of the caffeine-induced Ca2+ transient, is insufficient to maintain a normal diastolic Ca2+ during high rates of stimulation. Although a high SR Ca2+ release following excitation is maintained, the hypercontractile state is not maintained at high rates of stimulation, and signs of both systolic and diastolic contractile failure appear. Thus, the dilated cardiomyopathy that evolves in this mouse model exhibits signs of both systolic and diastolic failure, but not a deficient SR Ca2+ loading or release, as occurs in some other cardiomyopathic models.
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Ebert AM, McAnelly CA, Srinivasan A, Mueller RL, Garrity DB, Garrity DM. The calcium channel beta2 (CACNB2) subunit repertoire in teleosts. BMC Mol Biol 2008; 9:38. [PMID: 18419826 PMCID: PMC2365960 DOI: 10.1186/1471-2199-9-38] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Accepted: 04/17/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cardiomyocyte contraction is initiated by influx of extracellular calcium through voltage-gated calcium channels. These oligomeric channels utilize auxiliary beta subunits to chaperone the pore-forming alpha subunit to the plasma membrane, and to modulate channel electrophysiology 1. Several beta subunit family members are detected by RT-PCR in the embryonic heart. Null mutations in mouse beta2, but not in the other three beta family members, are embryonic lethal at E10.5 due to defects in cardiac contractility 2. However, a drawback of the mouse model is that embryonic heart rhythm is difficult to study in live embryos due to their intra-uterine development. Moreover, phenotypes may be obscured by secondary effects of hypoxia. As a first step towards developing a model for contributions of beta subunits to the onset of embryonic heart rhythm, we characterized the structure and expression of beta2 subunits in zebrafish and other teleosts. RESULTS Cloning of two zebrafish beta2 subunit genes (beta2.1 and beta2.2) indicated they are membrane-associated guanylate kinase (MAGUK)-family genes. Zebrafish beta2 genes show high conservation with mammals within the SH3 and guanylate kinase domains that comprise the "core" of MAGUK proteins, but beta2.2 is much more divergent in sequence than beta2.1. Alternative splicing occurs at the N-terminus and within the internal HOOK domain. In both beta2 genes, alternative short ATG-containing first exons are separated by some of the largest introns in the genome, suggesting that individual transcript variants could be subject to independent cis-regulatory control. In the Tetraodon nigrovidis and Fugu rubripes genomes, we identified single beta2 subunit gene loci. Comparative analysis of the teleost and human beta2 loci indicates that the short 5' exon sequences are highly conserved. A subset of 5' exons appear to be unique to teleost genomes, while others are shared with mammals. Alternative splicing is temporally and spatially regulated in embryo and adult. Moreover, a different subset of spliced beta2 transcript variants is detected in the embryonic heart compared to the adult. CONCLUSION These studies refine our understanding of beta2 subunit diversity arising from alternative splicing, and provide the groundwork for functional analysis of beta2 subunit diversity in the embryonic heart.
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Affiliation(s)
- Alicia M Ebert
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
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Role of Ca
V
β Subunits, and Lack of Functional Reserve, in Protein Kinase A Modulation of Cardiac Ca
V
1.2 Channels. Circ Res 2008; 102:e54-64. [DOI: 10.1161/circresaha.108.171736] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Protein kinase A (PKA)-mediated enhancement of L-type calcium currents (
I
Ca,L
) is essential for sympathetic regulation of the heartbeat and is the classic example of channel regulation by phosphorylation, and its loss is a common hallmark of heart failure. Mechanistic understanding of how distinct Ca
V
channel subunits contribute to PKA modulation of
I
Ca,L
has been intensely pursued yet remains elusive. Moreover, critical features of this regulation such as its functional reserve (the surplus capacity available for modulation) in the heart are unknown. Here, we use an overexpression paradigm in heart cells to simultaneously identify the impact of auxiliary Ca
V
βs on PKA modulation of
I
Ca,L
and to gauge the functional reserve of this regulation in the heart. Ca
V
1.2 channels containing wild-type β
2a
or a phosphorylation-deficient mutant (β
2a,AAA
) were equally upregulated by PKA, discounting a necessary role for β phosphorylation. Nevertheless, channels reconstituted with β
2a
displayed a significantly diminished PKA response compared with other β isoforms, an effect explainable by a uniquely higher basal
P
o
of β
2a
channels. Overexpression of all βs increased basal current density, accompanied by a concomitant decrease in the magnitude of PKA regulation. Scatter plots of fold increase in current against basal current density revealed an inverse relationship that was conserved across species and conformed to a model in which a large fraction of channels remained unmodified after PKA activation. These results redefine the role of β subunits in PKA modulation of Ca
V
1.2 channels and uncover a new design principle of this phenomenon in the heart, vis à vis a limited functional reserve.
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Michels G, Er F, Khan IF, Endres-Becker J, Brandt MC, Gassanov N, Johns DC, Hoppe UC. K+ channel regulator KCR1 suppresses heart rhythm by modulating the pacemaker current If. PLoS One 2008; 3:e1511. [PMID: 18231597 PMCID: PMC2204056 DOI: 10.1371/journal.pone.0001511] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 12/22/2007] [Indexed: 01/20/2023] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide sensitive (HCN) channels underlie the pacemaker current I(f), which plays an essential role in spontaneous cardiac activity. HCN channel subunits (HCN1-4) are believed to be modulated by additional regulatory proteins, which still have to be identified. Using biochemistry, molecularbiology and electrophysiology methods we demonstrate a protein-protein interaction between HCN2 and the K(+) channel regulator protein 1, named KCR1. In coimmunoprecipitation experiments we show that KCR1 and HCN2 proteins are able to associate. Heterologously expressed HCN2 whole-cell current density was significantly decreased by KCR1. KCR1 profoundly suppressed I(HCN2) single-channel activity, indicating a functional interaction between KCR1 and the HCN2 channel subunit. Endogenous KCR1 expression could be detected in adult and neonatal rat ventriculocytes. Adenoviral-mediated overexpression of KCR1 in rat cardiomyocytes (i) reduced I(f) whole-cell currents, (ii) suppressed most single-channel gating parameters, (iii) altered the activation kinetics, (iv) suppressed spontaneous action potential activity, and (v) the beating rate. More importantly, siRNA-based knock-down of endogenous KCR1 increased the native I(f) current size and single-channel activity and accelerated spontaneous beating rate, supporting an inhibitory action of endogenous KCR1 on native I(f). Our observations demonstrate for the first time that KCR1 modulates I(HCN2)/I(f) channel gating and indicate that KCR1 serves as a regulator of cardiac automaticity.
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Affiliation(s)
- Guido Michels
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
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Usefulness of myocardial performance index and biochemical markers for early detection of anthracycline-induced cardiotoxicity in adults. Clin Res Cardiol 2008; 97:318-26. [PMID: 18193371 DOI: 10.1007/s00392-007-0633-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2007] [Accepted: 11/20/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Anthracycline therapy is limited by cardiotoxicity. Currently no diagnostic parameter is available allowing ubiquitous and reliable detection of preclinical anthracycline cardiomyopathy and prediction of prognosis. PATIENTS AND METHODS In 100 consecutive patients receiving anthracycline-based chemotherapy serial measurements of left ventricular systolic and diastolic function, Tei index (a Doppler echocardiographic parameter of global ventricular function), cardiac troponin T (cTnT) and NT-probrain natriuretic peptides (BNP) at baseline and during 1-year follow-up were performed. RESULTS Mean ejection fraction (LVEF) significantly decreased immediately after completion of anthracycline therapy (mean dose 226.1 +/- 8.3 mg/m(2)) und further declined during follow-up (65.9 +/- 0.6% Vs. 61.6 +/- 0.7%; P < 0.001), while mean E/A ratio decreased after 6 months (P = 0.05). No patient presented with cardiac symptoms. The Tei index increased after therapy in the majority of patients (78.8%) compared with pre-therapy values indicating myocardial alteration in more patients than previously recognized. cTnT levels did not exceed the upper limit of the normal range in any patient. Seven patients had low-level elevations of cTnT. Only one of these patients developed a concomitant decrease in LVEF. Mean N-terminal-pro-BNP (NT-proBNP) levels did not significantly change after anthracycline administration. However, in 13 patients (15.3%) a marked, transient increase of NT-proBNP was obtained after the first anthracycline cycle without cardiac dysfunction presumably due to altered cardiac loading conditions during chemotherapy. CONCLUSION Low to moderate doses of anthracyclines resulted in subclinical myocardial alteration in more patients than so far noticed. Clinical implications of increased Tei index remain to be determined in long-term. Our results do not support that assessment of cTnT or BNP levels may safely replace serial echocardiographic evaluation of systolic and diastolic function for the monitoring of anthracycline cardiotoxicity.
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