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Zheng J, Dooge HC, Pérez-Hernández M, Zhao YT, Chen X, Hernandez JJ, Valdivia CR, Palomeque J, Rothenberg E, Delmar M, Valdivia HH, Alvarado FJ. Preserved cardiac performance and adrenergic response in a rabbit model with decreased ryanodine receptor 2 expression. J Mol Cell Cardiol 2022; 167:118-128. [PMID: 35413295 PMCID: PMC9610860 DOI: 10.1016/j.yjmcc.2022.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/11/2022] [Accepted: 04/06/2022] [Indexed: 11/19/2022]
Abstract
Ryanodine receptor 2 (RyR2) is an ion channel in the heart responsible for releasing into the cytosol most of the Ca2+ required for contraction. Proper regulation of RyR2 is critical, as highlighted by the association between channel dysfunction and cardiac arrhythmia. Lower RyR2 expression is also observed in some forms of heart disease; however, there is limited information on the impact of this change on excitation-contraction (e-c) coupling, Ca2+-dependent arrhythmias, and cardiac performance. We used a constitutive knock-out of RyR2 in rabbits (RyR2-KO) to assess the extent to which a stable decrease in RyR2 expression modulates Ca2+ handling in the heart. We found that homozygous knock-out of RyR2 in rabbits is embryonic lethal. Remarkably, heterozygotes (KO+/-) show ~50% loss of RyR2 protein without developing an overt phenotype at the intact animal and whole heart levels. Instead, we found that KO+/- myocytes show (1) remodeling of RyR2 clusters, favoring smaller groups in which channels are more densely arranged; (2) lower Ca2+ spark frequency and amplitude; (3) slower rate of Ca2+ release and mild but significant desynchronization of the Ca2+ transient; and (4) a significant decrease in the basal phosphorylation of S2031, likely due to increased association between RyR2 and PP2A. Our data show that RyR2 deficiency, although remarkable at the molecular and subcellular level, has only a modest impact on global Ca2+ release and is fully compensated at the whole-heart level. This highlights the redundancy of RyR2 protein expression and the plasticity of the e-c coupling apparatus.
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Affiliation(s)
- Jingjing Zheng
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA; Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Holly C Dooge
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Marta Pérez-Hernández
- Leon H Charney Division of Cardiology, New York University Grossman School of Medicine,. New York, NY, United States of America
| | - Yan-Ting Zhao
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, United States of America
| | - Xi Chen
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States of America
| | - Jonathan J Hernandez
- Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, United States of America
| | - Carmen R Valdivia
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Julieta Palomeque
- Centro de Investigaciones Cardiovasculares, CCT-La Plata-CONICET, Facultad de Ciencias Médicas, UNLP, La Plata, Argentina
| | - Eli Rothenberg
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, United States of America
| | - Mario Delmar
- Leon H Charney Division of Cardiology, New York University Grossman School of Medicine,. New York, NY, United States of America
| | - Héctor H Valdivia
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Francisco J Alvarado
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
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Lyon A, van Opbergen CJM, Delmar M, Heijman J, van Veen TAB. In silico Identification of Disrupted Myocardial Calcium Homeostasis as Proarrhythmic Trigger in Arrhythmogenic Cardiomyopathy. Front Physiol 2021; 12:732573. [PMID: 34630150 PMCID: PMC8497808 DOI: 10.3389/fphys.2021.732573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/27/2021] [Indexed: 11/30/2022] Open
Abstract
Background: Patients with arrhythmogenic cardiomyopathy may suffer from lethal ventricular arrhythmias. Arrhythmogenic cardiomyopathy is predominantly triggered by mutations in plakophilin-2, a key component of cell-to-cell adhesion and calcium cycling regulation in cardiomyocytes. Calcium dysregulation due to plakophilin-2 mutations may lead to arrhythmias but the underlying pro-arrhythmic mechanisms remain unclear. Aim: To unravel the mechanisms by which calcium-handling abnormalities in plakophilin-2 loss-of-function may contribute to proarrhythmic events in arrhythmogenic cardiomyopathy. Methods: We adapted a computer model of mouse ventricular electrophysiology using recent experimental calcium-handling data from plakophilin-2 conditional knock-out (PKP2-cKO) mice. We simulated individual effects of beta-adrenergic stimulation, modifications in connexin43-mediated calcium entry, sodium-calcium exchanger (NCX) activity and ryanodine-receptor 2 (RyR2) calcium affinity on cellular electrophysiology and occurrence of arrhythmogenic events (delayed-afterdepolarizations). A population-of-models approach was used to investigate the generalizability of our findings. Finally, we assessed the potential translation of proposed mechanisms to humans, using a human ventricular cardiomyocyte computational model. Results: The model robustly reproduced the experimental calcium-handling changes in PKP2-cKO cardiomyocytes: an increased calcium transient amplitude (562 vs. 383 nM), increased diastolic calcium (120 vs. 91 nM), reduced L-type calcium current (15.0 vs. 21.4 pA/pF) and an increased free SR calcium (0.69 vs. 0.50 mM). Under beta-adrenergic stimulation, PKP2-cKO models from the population of models (n = 61) showed a higher susceptibility to delayed-afterdepolarizations compared to control (41 vs. 3.3%). Increased connexin43-mediated calcium entry further elevated the number of delayed-afterdepolarizations (78.7%, 2.5-fold increase in background calcium influx). Elevated diastolic cleft calcium appeared responsible for the increased RyR2-mediated calcium leak, promoting delayed-afterdepolarizations occurrence. A reduction in RyR2 calcium affinity prevented delayed-afterdepolarizations in PKP2-cKO models (24.6 vs. 41%). An additional increase in INCX strongly reduced delayed-afterdepolarizations occurrence, by lowering diastolic cleft calcium levels. The human model showed similar outcomes, suggesting a potential translational value of these findings. Conclusion: Beta-adrenergic stimulation and connexin43-mediated calcium entry upon loss of plakophilin-2 function contribute to generation of delayed-afterdepolarizations. RyR2 and NCX dysregulation play a key role in modulating these proarrhythmic events. This work provides insights into potential future antiarrhythmic strategies in arrhythmogenic cardiomyopathy due to plakophilin-2 loss-of-function.
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Affiliation(s)
- Aurore Lyon
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Chantal J M van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, United States
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, United States
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Toon A B van Veen
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, Netherlands
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3
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Aguilar-Sanchez Y, Rodriguez de Yurre A, Argenziano M, Escobar AL, Ramos-Franco J. Transmural Autonomic Regulation of Cardiac Contractility at the Intact Heart Level. Front Physiol 2019; 10:773. [PMID: 31333477 PMCID: PMC6616252 DOI: 10.3389/fphys.2019.00773] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 06/03/2019] [Indexed: 01/14/2023] Open
Abstract
The relationship between cardiac excitability and contractility depends on when Ca2+ influx occurs during the ventricular action potential (AP). In mammals, it is accepted that Ca2+ influx through the L-type Ca2+ channels occurs during AP phase 2. However, in murine models, experimental evidence shows Ca2+ influx takes place during phase 1. Interestingly, Ca2+ influx that activates contraction is highly regulated by the autonomic nervous system. Indeed, autonomic regulation exerts multiple effects on Ca2+ handling and cardiac electrophysiology. In this paper, we explore autonomic regulation in endocardial and epicardial layers of intact beating mice hearts to evaluate their role on cardiac excitability and contractility. We hypothesize that in mouse cardiac ventricles the influx of Ca2+ that triggers excitation–contraction coupling (ECC) does not occur during phase 2. Using pulsed local field fluorescence microscopy and loose patch photolysis, we show sympathetic stimulation by isoproterenol increased the amplitude of Ca2+ transients in both layers. This increase in contractility was driven by an increase in amplitude and duration of the L-type Ca2+ current during phase 1. Interestingly, the β-adrenergic increase of Ca2+ influx slowed the repolarization of phase 1, suggesting a competition between Ca2+ and K+ currents during this phase. In addition, cAMP activated L-type Ca2+ currents before SR Ca2+ release activated the Na+-Ca2+ exchanger currents, indicating Cav1.2 channels are the initial target of PKA phosphorylation. In contrast, parasympathetic stimulation by carbachol did not have a substantial effect on amplitude and kinetics of endocardial and epicardial Ca2+ transients. However, carbachol transiently decreased the duration of the AP late phase 2 repolarization. The carbachol-induced shortening of phase 2 did not have a considerable effect on ventricular pressure and systolic Ca2+ dynamics. Interestingly, blockade of muscarinic receptors by atropine prolonged the duration of phase 2 indicating that, in isolated hearts, there is an intrinsic release of acetylcholine. In addition, the acceleration of repolarization induced by carbachol was blocked by the acetylcholine-mediated K+ current inhibition. Our results reveal the transmural ramifications of autonomic regulation in intact mice hearts and support our hypothesis that Ca2+ influx that triggers ECC occurs in AP phase 1 and not in phase 2.
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Affiliation(s)
- Yuriana Aguilar-Sanchez
- Department of Physiology and Biophysics, School of Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Ainhoa Rodriguez de Yurre
- Laboratorio de Cardio Inmunologia, Instituto de Biofisica Carlos Chagas Filho, Rio de Janeiro, Brazil
| | - Mariana Argenziano
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Ariel L Escobar
- Department of Bioengineering, School of Engineering, University of California, Merced, Merced, CA, United States
| | - Josefina Ramos-Franco
- Department of Physiology and Biophysics, School of Medicine, Rush University Medical Center, Chicago, IL, United States
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Bode D, Lindner D, Schwarzl M, Westermann D, Deissler P, Primessnig U, Hegemann N, Blatter LA, van Linthout S, Tschöpe C, Schoenrath F, Soltani S, Stamm C, Duesterhoeft V, Rolim N, Wisløff U, Knosalla C, Falk V, Pieske BM, Heinzel FR, Hohendanner F. The role of fibroblast - Cardiomyocyte interaction for atrial dysfunction in HFpEF and hypertensive heart disease. J Mol Cell Cardiol 2019; 131:53-65. [PMID: 31005484 DOI: 10.1016/j.yjmcc.2019.04.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 04/17/2019] [Indexed: 12/28/2022]
Abstract
AIMS Atrial contractile dysfunction is associated with increased mortality in heart failure (HF). We have shown previously that a metabolic syndrome-based model of HFpEF and a model of hypertensive heart disease (HHD) have impaired left atrial (LA) function in vivo (rat). In this study we postulate, that left atrial cardiomyocyte (CM) and cardiac fibroblast (CF) paracrine interaction related to the inositol 1,4,5-trisphosphate signalling cascade is pivotal for the manifestation of atrial mechanical dysfunction in HF and that quantitative atrial remodeling is highly disease-dependent. METHODS AND RESULTS Differential remodeling was observed in HHD and HFpEF as indicated by an increase of atrial size in vivo (HFpEF), unchanged fibrosis (HHD and HFpEF) and a decrease of CM size (HHD). Baseline contractile performance of rat CM in vitro was enhanced in HFpEF. Upon treatment with conditioned medium from their respective stretched CF (CM-SF), CM (at 21 weeks) of WT showed increased Ca2+ transient (CaT) amplitudes related to the paracrine activity of the inotrope endothelin (ET-1) and inositol 1,4,5-trisphosphate induced Ca2+ release. Concentration of ET-1 was increased in CM-SF and atrial tissue from WT as compared to HHD and HFpEF. In HHD, CM-SF had no relevant effect on CaT kinetics. However, in HFpEF, CM-SF increased diastolic Ca2+ and slowed Ca2+ removal, potentially contributing to an in-vivo decompensation. During disease progression (i.e. at 27 weeks), HFpEF displayed dysfunctional excitation-contraction-coupling (ECC) due to lower sarcoplasmic-reticulum Ca2+ content unrelated to CF-CM interaction or ET-1, but associated with enhanced nuclear [Ca2+]. In human patients, tissue ET-1 was not related to the presence of arterial hypertension or obesity. CONCLUSIONS Atrial remodeling is a complex entity that is highly disease and stage dependent. The activity of fibrosis related to paracrine interaction (e.g. ET-1) might contribute to in vitro and in vivo atrial dysfunction. However, during later stages of disease, ECC is impaired unrelated to CF.
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Affiliation(s)
- David Bode
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Diana Lindner
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg, Germany; Universitäres Herzzentrum Hamburg, Klinik für Allgemeine und Interventionelle Kardiologie, 20246 Hamburg, Germany
| | - Michael Schwarzl
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg, Germany; Universitäres Herzzentrum Hamburg, Klinik für Allgemeine und Interventionelle Kardiologie, 20246 Hamburg, Germany
| | - Dirk Westermann
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg, Germany; Universitäres Herzzentrum Hamburg, Klinik für Allgemeine und Interventionelle Kardiologie, 20246 Hamburg, Germany
| | - Peter Deissler
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Uwe Primessnig
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Niklas Hegemann
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Lothar A Blatter
- Department of Physiology and Biophysics, Rush University, Chicago, USA
| | - Sophie van Linthout
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Carsten Tschöpe
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Felix Schoenrath
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany
| | - Sajjad Soltani
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany
| | - Christof Stamm
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany
| | - Volker Duesterhoeft
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany
| | - Natale Rolim
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Ulrik Wisløff
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Christoph Knosalla
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany
| | - Volkmar Falk
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Department of Cardiothoracic Surgery, German Heart Center Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany; Department of Cardiothoracic Surgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany
| | - Burkert M Pieske
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany; Department of Internal Medicine and Cardiology, German Heart Center Berlin, 13353 Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburgerplatz 1, 13353 Berlin, Germany; DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany.
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Scardigli M, Ferrantini C, Crocini C, Pavone FS, Sacconi L. Interplay Between Sub-Cellular Alterations of Calcium Release and T-Tubular Defects in Cardiac Diseases. Front Physiol 2018; 9:1474. [PMID: 30410446 PMCID: PMC6209824 DOI: 10.3389/fphys.2018.01474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/28/2018] [Indexed: 12/19/2022] Open
Abstract
Asynchronous Ca2+ release promotes non-homogeneous myofilament activation, leading to mechanical dysfunction, as well as initiation of propagated calcium waves and arrhythmias. Recent advances in microscopy techniques have allowed for optical recordings of local Ca2+ fluxes and action potentials from multiple sub-cellular domains within cardiac cells with unprecedented spatial and temporal resolution. Since then, sub-cellular local information of the spatio-temporal relationship between Ca2+ release and action potential propagation have been unlocked, providing novel mechanistic insights in cardiac excitation-contraction coupling (ECC). Here, we review the promising perspectives arouse from repeatedly probing Ca2+ release at the same sub-cellular location while simultaneously probing multiple locations at the same time within a single cardiac cell. We also compare the results obtained in three different rodent models of cardiac diseases, highlighting disease-specific mechanisms. Slower local Ca2+ release has been observed in regions with defective action potential conduction in diseased cardiac cells. Moreover, significant increment of Ca2+ variability (both in time and in space) has been found in diseased cardiac cells but does not directly correlate with local electrical defects nor with the degree of structural aberrations of the cellular membrane system, suggesting a role for other players of the ECC machinery. We finally explore exciting opportunities provided by the technology for studying different cardiomyocyte populations, as well as for dissecting the mechanisms responsible for subcellular spatio-temporal variability of Ca2+ release.
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Affiliation(s)
- Marina Scardigli
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
| | - Cecilia Ferrantini
- European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology & BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Francesco S Pavone
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy.,Department of Physics and Astronomy, University of Florence, Florence, Italy
| | - Leonardo Sacconi
- National Institute of Optics, National Research Council, Florence, Italy.,European Laboratory for Non-Linear Spectroscopy, Florence, Italy
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6
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Anesthetics, the Ryanodine Receptors, and the Heart. Anesthesiology 2017; 126:373-375. [PMID: 28079565 DOI: 10.1097/aln.0000000000001520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Liu B, Ho HT, Velez-Cortes F, Lou Q, Valdivia CR, Knollmann BC, Valdivia HH, Gyorke S. Genetic ablation of ryanodine receptor 2 phosphorylation at Ser-2808 aggravates Ca(2+)-dependent cardiomyopathy by exacerbating diastolic Ca2+ release. J Physiol 2014; 592:1957-73. [PMID: 24445321 DOI: 10.1113/jphysiol.2013.264689] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Phosphorylation of the cardiac ryanodine receptor (RyR2) by protein kinase A (PKA) at Ser-2808 is suggested to mediate the physiological 'fight or flight' response and contribute to heart failure by rendering the sarcoplasmic reticulum (SR) leaky for Ca(2+). In the present study, we examined the potential role of RyR2 phosphorylation at Ser-2808 in the progression of Ca(2+)-dependent cardiomyopathy (CCM) by using mice genetically modified to feature elevated SR Ca(2+) leak while expressing RyR2s that cannot be phosphorylated at this site (S2808A). Surprisingly, rather than alleviating the disease phenotype, constitutive dephosphorylation of Ser-2808 aggravated CCM as manifested by shortened survival, deteriorated in vivo cardiac function, exacerbated SR Ca(2+) leak and mitochondrial injury. Notably, the deteriorations of cardiac function, myocyte Ca(2+) handling, and mitochondria integrity were consistently worse in mice with heterozygous ablation of Ser-2808 than in mice with complete ablation. Wild-type (WT) and CCM myocytes expressing unmutated RyR2s exhibited a high level of baseline phosphorylation at Ser-2808. Exposure of these CCM cells to protein phosphatase 1 caused a transitory increase in Ca(2+) leak attributable to partial dephosphorylation of RyR2 tetramers at Ser-2808 from more fully phosphorylated state. Thus, exacerbated Ca(2+) leak through partially dephosphorylated RyR2s accounts for the prevalence of the disease phenotype in the heterozygous S2808A CCM mice. These results do not support the importance of RyR2 hyperphosphorylation in Ca(2+)-dependent heart disease, and rather suggest roles for the opposite process, the RyR2 dephosphorylation at this residue in physiological and pathophysiological Ca(2+) signalling.
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Affiliation(s)
- Bin Liu
- Department of Physiology and Cell Biology, 507 Davis Heart & Lung Research Institute (office), 473 W. 12th Avenue, Columbus, OH 43210, USA.
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8
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Ruhle B, Trebak M. Emerging roles for native Orai Ca2+ channels in cardiovascular disease. CURRENT TOPICS IN MEMBRANES 2013; 71:209-35. [PMID: 23890117 DOI: 10.1016/b978-0-12-407870-3.00009-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Orai proteins form highly calcium (Ca(2+))-selective channels located in the plasma membrane of both nonexcitable and excitable cells, where they make important contributions to many cellular processes. The well-characterized Ca(2+) release-activated Ca(2+) current is mediated by Orai1 multimers and is activated, upon depletion of inositol 1,4,5-trisphosphate-sensitive stores, by direct interaction of Orai1 with the endoplasmic reticulum Ca(2+) sensor, stromal interaction molecule 1 (STIM1). This pathway is known as capacitative Ca(2+) entry or store-operated Ca(2+) entry. While most investigations have focused on STIM1 and Orai1 in their store-dependent mode, emerging evidence suggests that Orai1 and Orai3 heteromultimeric channels can form store-independent Ca(2+)-selective channels. The role of store-dependent and store-independent channels in excitation-transcription coupling and the pathological remodeling of the cardiovascular system are beginning to come forth. Recent evidence suggests that STIM/Orai-generated Ca(2+) signaling couples to gene transcription and subsequent phenotypic changes associated with the processes of cardiac and vascular remodeling. This short review will explore the contributions of native Orai channels to heart and vessel physiology and their role in cardiovascular diseases.
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Affiliation(s)
- Brian Ruhle
- Nanobioscience Constellation, The College of Nanoscale Science and Engineering, University at Albany-State University of New York, Albany, NY, USA
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9
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Tian X, Liu Y, Liu Y, Wang R, Wagenknecht T, Liu Z, Chen SRW. Ligand-dependent conformational changes in the clamp region of the cardiac ryanodine receptor. J Biol Chem 2012; 288:4066-75. [PMID: 23258540 DOI: 10.1074/jbc.m112.427864] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Global conformational changes in the three-dimensional structure of the Ca(2+) release channel/ryanodine receptor (RyR) occur upon ligand activation. A number of ligands are able to activate the RyR channel, but whether these structurally diverse ligands induce the same or different conformational changes in the channel is largely unknown. Here we constructed a fluorescence resonance energy transfer (FRET)-based probe by inserting a CFP after residue Ser-2367 and a YFP after residue Tyr-2801 in the cardiac RyR (RyR2) to yield a CFP- and YFP-dual labeled RyR2 (RyR2(Ser-2367-CFP/Tyr-2801-YFP)). Both of these insertion sites have previously been mapped to the "clamp" region in the four corners of the square-shaped cytoplasmic assembly of the three-dimensional structure of RyR2. Using this novel FRET probe, we monitored the extent of conformational changes in the clamp region of RyR2(Ser-2367-CFP/Tyr-2801-YFP) induced by various ligands. We also monitored the extent of Ca(2+) release induced by the same ligands in HEK293 cells expressing RyR2(Ser-2367-CFP/Tyr-2801-YFP). We detected conformational changes in the clamp region for the ligands caffeine, aminophylline, theophylline, ATP, and ryanodine but not for Ca(2+) or 4-chloro-m-cresol, although they all induced Ca(2+) release. Interestingly, caffeine is able to induce further conformational changes in the clamp region of the ryanodine-modified channel, suggesting that ryanodine does not lock RyR in a fixed conformation. Our data demonstrate that conformational changes in the clamp region of RyR are ligand-dependent and suggest the existence of multiple ligand dependent RyR activation mechanisms associated with distinct conformational changes.
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Affiliation(s)
- Xixi Tian
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology and Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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10
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Cui X, Rovetti RJ, Yang L, Garfinkel A, Weiss JN, Qu Z. Period-doubling bifurcation in an array of coupled stochastically excitable elements subjected to global periodic forcing. PHYSICAL REVIEW LETTERS 2009; 103:044102. [PMID: 19659359 PMCID: PMC2761886 DOI: 10.1103/physrevlett.103.044102] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Indexed: 05/15/2023]
Abstract
The collective behaviors of coupled, stochastically excitable elements subjected to global periodic forcing are investigated numerically and analytically. We show that the whole system undergoes a period-doubling bifurcation as the driving period decreases, while the individual elements still exhibit random excitations. Using a mean-field representation, we show that this macroscopic bifurcation behavior is caused by interactions between the random excitation, the refractory period, and recruitment (spatial cooperativity) of the excitable elements.
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Affiliation(s)
- Xiaohua Cui
- Department of Physiological Science, University of California, Los Angeles, California 90095, USA
- Department of Physics, Beijing Normal University, Beijing 100875, P.R. China
| | - Robert J. Rovetti
- Department of Mathematics, Loyola Marymount University, Los Angeles, California 90045, USA
| | - Ling Yang
- Center for Systems Biology, Shuzhou University, Jiangsu 215006, P.R. China
| | - Alan Garfinkel
- Department of Physiological Science, University of California, Los Angeles, California 90095, USA
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Correspondence to:
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11
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Barrientos G, Bose DD, Feng W, Padilla I, Pessah IN. The Na+/Ca2+ exchange inhibitor 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate (KB-R7943) also blocks ryanodine receptors type 1 (RyR1) and type 2 (RyR2) channels. Mol Pharmacol 2009; 76:560-8. [PMID: 19509218 DOI: 10.1124/mol.109.057265] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Na(+)/Ca(2+) exchanger (NCX) is a plasma membrane transporter that moves Ca(2+) in or out of the cell, depending on membrane potential and transmembrane ion gradients. NCX is the main pathway for Ca(2+) extrusion from excitable cells. NCX inhibitors can ameliorate cardiac ischemia-reperfusion injury and promote high-frequency fatigue of skeletal muscle, purportedly by inhibiting the Ca(2+) inward mode of NCX. Here we tested two known NCX inhibitors, 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)-isothiourea methanesulfonate (KB-R7943) and the structurally related 2-[[4-[(4-Nitrophenyl)methoxy]phenyl]methyl]-4-thiazoli dinecarboxylic acid ethyl ester (SN-6), for their influence on electrically or caffeine-evoked Ca(2+) transients in adult dissociated flexor digitorum brevis (FDB) skeletal muscle fibers and human embryonic kidney (HEK) 293 cells that have stable expression of type 1 ryanodine receptor (RyR1). KB-R7943 (< or = 10 microM) reversibly attenuates electrically evoked Ca(2+) transients in FDB and caffeine-induced Ca(2+) release in HEK 293, whereas the structurally related NCX inhibitor SN-6 does not, suggesting that KB-R7943 directly inhibits RyR1. In support of this interpretation, KB-R7943 inhibits high-affinity binding of [(3)H]ryanodine to RyR1 (IC(50) = 5.1 +/- 0.9 microM) and the cardiac isoform RyR2 (IC(50) = 13.4 +/- 1.8 microM). KB-R7943 interfered with the gating of reconstituted RyR1 and RyR2 channels, reducing open probability (P(o)), shortening mean open time, and prolonging mean closed time. KB-R7943 was more effective at blocking RyR1 with cytoplasmic conditions favoring high P(o) compared with those favoring low P(o). SN-6 has negligible activity toward altering [(3)H]ryanodine binding of RyR1 and RyR2. Our results identify that KB-R7943 is a reversible, activity-dependent blocker of the two most broadly expressed RyR channel isoforms and contributes to its pharmacological and therapeutic activities.
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Affiliation(s)
- Genaro Barrientos
- Department of Molecular Biosciences, School of Veterinary Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
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12
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Cardiac cell: a biological laser? Biosystems 2008; 92:49-60. [PMID: 18191016 DOI: 10.1016/j.biosystems.2007.11.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 10/30/2007] [Accepted: 11/26/2007] [Indexed: 11/23/2022]
Abstract
We present a new concept of cardiac cells based on an analogy with lasers, practical implementations of quantum resonators. In this concept, each cardiac cell comprises a network of independent nodes, characterised by a set of discrete energy levels and certain transition probabilities between them. Interaction between the nodes is given by threshold-limited energy transfer, leading to quantum-like behaviour of the whole network. We propose that in cardiomyocytes, during each excitation-contraction coupling cycle, stochastic calcium release and the unitary properties of ionic channels constitute an analogue to laser active medium prone to "population inversion" and "spontaneous emission" phenomena. This medium, when powered by an incoming threshold-reaching voltage discharge in the form of an action potential, responds to the calcium influx through L-type calcium channels by stimulated emission of Ca2+ ions in a coherent, synchronised and amplified release process known as calcium-induced calcium release. In parallel, phosphorylation-stimulated molecular amplification in protein cascades adds tuneable features to the cells. In this framework, the heart can be viewed as a coherent network of synchronously firing cardiomyocytes behaving as pulsed laser-like amplifiers, coupled to pulse-generating pacemaker master-oscillators. The concept brings a new viewpoint on cardiac diseases as possible alterations of "cell lasing" properties.
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13
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Pizzo P, Pozzan T. Mitochondria–endoplasmic reticulum choreography: structure and signaling dynamics. Trends Cell Biol 2007; 17:511-7. [PMID: 17851078 DOI: 10.1016/j.tcb.2007.07.011] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 07/02/2007] [Accepted: 07/17/2007] [Indexed: 01/06/2023]
Abstract
Mitochondria and endoplasmic reticulum (ER) have different roles in living cells but they interact both physically and functionally. A key aspect of the mitochondria-ER relationship is the modulation of Ca(2+) signaling during cell activation, which thus affects a variety of physiological processes. We focus here on the molecular aspects that control the dynamics of the organelle-organelle interaction and their relationship with Ca(2+) signals, also discussing the consequences that these phenomena have, not only for cell physiology but also in the control of cell death.
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Affiliation(s)
- Paola Pizzo
- Department Biomedical Sciences, University of Padua, Viale G. Colombo 3, 35121 Padua, Italy.
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14
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Beharier O, Etzion Y, Katz A, Friedman H, Tenbosh N, Zacharish S, Bereza S, Goshen U, Moran A. Crosstalk between L-type calcium channels and ZnT-1, a new player in rate-dependent cardiac electrical remodeling. Cell Calcium 2007; 42:71-82. [PMID: 17196651 DOI: 10.1016/j.ceca.2006.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 11/19/2006] [Accepted: 11/21/2006] [Indexed: 10/23/2022]
Abstract
Crosstalk between two membrane transport systems is an established mechanism underlying regulation. In this study, we investigated the interaction between ZnT-1, a putative plasma membrane zinc transporter, and L-type voltage-dependent calcium channels (LTCC). In the atrium of the myocardium decreased activity of the LTCC is a dominant feature of patients with atrial fibrillation. The trigger for this inhibition has been attributed to the rapid firing rates and consequent calcium overload in the atrial cardiomyocytes. However, the underlying mechanism of LTCC inhibition is still to be elucidated. Here, we showed that the expression of ZnT-1 inhibits the activity of L-type channels during electrical remodeling induced by rapid pacing. (i) Direct manipulations of ZnT-1 expression in cultured cardiomyocytes either by ZnT-1 overexpression or by ZnT-1 silencing with siRNA, decreased or enhanced, respectively, the barium influx through the LTCC. (ii) Co-expression of ZnT-1 with LTCC in Xenopus oocytes decreased whole cell barium current through LTCC. (iii) Rapid pacing of cultured cardiomyocytes (4 h, 100 ms cycle) increased ZnT-1 protein expression and inhibited the voltage-dependent divalent cation influx through the LTCC. Moreover, silencing ZnT-1 with siRNA prevented the rapid pacing induced inhibition of the LTCC (iv) Atrial pacing of anesthetized adult rats (4 h, 50 ms cycle) led to a significant increase in atrial ZnT-1 protein expression in parallel with the typical decrease of the refractory period in the atria. Taken together, these findings demonstrate that crosstalk between ZnT-1 and the L-type calcium channels may underlie atrial response to rapid pacing, suggesting that ZnT-1 is a significant participant in rate-dependent cardiac electrical remodeling.
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Affiliation(s)
- Ofer Beharier
- Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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15
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Michailova A, Saucerman J, Belik ME, McCulloch AD. Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+. Biophys J 2005; 88:2234-49. [PMID: 15738467 PMCID: PMC1305273 DOI: 10.1529/biophysj.104.046284] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.
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Affiliation(s)
- Anushka Michailova
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA.
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16
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Tavi P, Hansson A, Zhang SJ, Larsson NG, Westerblad H. Abnormal Ca(2+) release and catecholamine-induced arrhythmias in mitochondrial cardiomyopathy. Hum Mol Genet 2005; 14:1069-76. [PMID: 15757973 DOI: 10.1093/hmg/ddi119] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mitochondrial dysfunction is implicated in numerous cardiac disorders. It has been assumed that the functional defects are directly related to a decreased rate of mitochondrial ATP production, but recent studies have challenged this idea. Here, we used mice with tissue-specific knockout of mitochondrial transcription factor A (Tfam) that leads to progressive cardiomyopathy. The role of changes in the excitation-contraction (E-C) coupling in cardiomyocytes of these mice was studied by measuring the free cytosolic Ca(2+) concentration and by analyzing the expression of genes encoding E-C coupling proteins. Action potential-mediated Ca(2+) transients, measured with the fluorescent indicator fluo-3 in isolated cardiomyocytes, were smaller and faster in Tfam knockout cardiomyocytes when compared with controls. The total sarcoplasmic reticulum (SR) Ca(2+) content was decreased in Tfam knockout cells. The gene for the SR Ca(2+) binding protein calsequestrin-2 (CASQ2), as well as other genes encoding proteins involved in SR Ca(2+) handling, showed decreased expression in Tfam knockout hearts. Decreased CASQ2 levels have been linked to severe arrhythmias triggered by beta-adrenergic stimulation. In line with this, application of the beta-adrenergic agonist isoproterenol resulted in frequent doublet Ca(2+) transients in Tfam knockout cardiomyocytes. In conclusion, our results show that mitochondrial dysfunction in the heart induces specific down-regulation of the expression of genes encoding proteins involved in E-C coupling. These changes predispose to cardiac arrhythmias and terminal heart failure and are thus important in the pathogenesis of mitochondrial cardiomyopathy.
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Affiliation(s)
- Pasi Tavi
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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