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Terrar DA. Calcium flux balance across cell membranes in the heart: important unanswered questions with implications for the role of ryanodine receptors. J Physiol 2024; 602:4687-4691. [PMID: 39097828 DOI: 10.1113/jp287223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Accepted: 07/12/2024] [Indexed: 08/05/2024] Open
Affiliation(s)
- Derek A Terrar
- Department of Pharmacology, University of Oxford, Oxford, UK
- UCL Institute of Cardiovascular Science, University College London, London, UK
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2
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Janicek R, Camors EM, Potenza DM, Fernandez-Tenorio M, Zhao Y, Dooge HC, Loaiza R, Alvarado FJ, Egger M, Valdivia HH, Niggli E. Dual ablation of the RyR2-Ser2808 and RyR2-Ser2814 sites increases propensity for pro-arrhythmic spontaneous Ca 2+ releases. J Physiol 2024. [PMID: 39316734 DOI: 10.1113/jp286453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 08/21/2024] [Indexed: 09/26/2024] Open
Abstract
During exercise or stress, the sympathetic system stimulates cardiac contractility via β-adrenergic receptor (β-AR) activation, resulting in phosphorylation of the cardiac ryanodine receptor (RyR2). Three RyR2 phosphorylation sites have taken prominence in excitation-contraction coupling: S2808 and S2030 are described as protein kinase A specific and S2814 as a Ca2+/calmodulin kinase type-2-specific site. To examine the contribution of these phosphosites to Ca2+ signalling, we generated double knock-in (DKI) mice in which Ser2808 and Ser2814 phosphorylation sites have both been replaced by alanine (RyR2-S2808A/S2814A). These mice did not exhibit an overt phenotype. Heart morphology and haemodynamic parameters were not altered. However, they had a higher susceptibility to arrhythmias. We performed confocal Ca2+ imaging and electrophysiology experiments. Isoprenaline was used to stimulate β-ARs. Measurements of Ca2+ waves and latencies in myocytes revealed an increased propensity for spontaneous Ca2+ releases in DKI myocytes, both in control conditions and during β-AR stimulation. In DKI cells, waves were initiated from a lower threshold concentration of Ca2+ inside the sarcoplasmic reticulum, suggesting higher Ca2+ sensitivity of the RyRs. The refractoriness of Ca2+ spark triggering depends on the Ca2+ sensitivity of the RyR2. We found that RyR2-S2808A/S2814A channels were more Ca2+ sensitive in control conditions. Isoprenaline further shortened RyR refractoriness in DKI cardiomyocytes. Together, our results suggest that ablation of both the RyR2-Ser2808 and RyR2-S2814 sites increases the propensity for pro-arrhythmic spontaneous Ca2+ releases, as previously suggested for hyperphosphorylated RyRs. Given that the DKI cells present a full response to isoprenaline, the data suggest that phosphorylation of Ser2030 might be sufficient for β-AR-mediated sensitization of RyRs. KEY POINTS: Phosphorylation of cardiac sarcoplasmic reticulum Ca2+-release channels (ryanodine receptors, RyRs) is involved in the regulation of cardiac function. Ablation of both the RyR2-Ser2808 and RyR2-Ser2814 sites increases the propensity for pro-arrhythmic spontaneous Ca2+ releases, as previously suggested for hyperphosphorylated RyRs. The intra-sarcoplasmic reticulum Ca2+ threshold for spontaneous Ca2+ wave generation is lower in RyR2-double-knock-in cells. The RyR2 from double-knock-in cells exhibits increased Ca2+ sensitivity. Phosphorylation of Ser2808 and Ser2814 might be important for basal activity of the channel. Phosphorylation of Ser2030 might be sufficient for a β-adrenergic response.
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Affiliation(s)
| | - Emmanuel M Camors
- Department of Pediatrics, Division of Cardiology, University of Tennessee Health Science Center, Le Bonheur Children's Hospital Research Center, Memphis, TN, USA
| | | | | | - Yanting Zhao
- Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Holly C Dooge
- Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Randall Loaiza
- Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Francisco J Alvarado
- Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Marcel Egger
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Hector H Valdivia
- Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
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Papa A, Zakharov SI, Katchman AN, Kushner JS, Chen BX, Yang L, Liu G, Jimenez AS, Eisert RJ, Bradshaw GA, Dun W, Ali SR, Rodriques A, Zhou K, Topkara V, Yang M, Morrow JP, Tsai EJ, Karlin A, Wan E, Kalocsay M, Pitt GS, Colecraft HM, Ben-Johny M, Marx SO. Rad regulation of Ca V1.2 channels controls cardiac fight-or-flight response. NATURE CARDIOVASCULAR RESEARCH 2022; 1:1022-1038. [PMID: 36424916 PMCID: PMC9681059 DOI: 10.1038/s44161-022-00157-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/29/2022] [Indexed: 11/16/2022]
Abstract
Fight-or-flight responses involve β-adrenergic-induced increases in heart rate and contractile force. In the present study, we uncover the primary mechanism underlying the heart's innate contractile reserve. We show that four protein kinase A (PKA)-phosphorylated residues in Rad, a calcium channel inhibitor, are crucial for controlling basal calcium current and essential for β-adrenergic augmentation of calcium influx in cardiomyocytes. Even with intact PKA signaling to other proteins modulating calcium handling, preventing adrenergic activation of calcium channels in Rad-phosphosite-mutant mice (4SA-Rad) has profound physiological effects: reduced heart rate with increased pauses, reduced basal contractility, near-complete attenuation of β-adrenergic contractile response and diminished exercise capacity. Conversely, expression of mutant calcium-channel β-subunits that cannot bind 4SA-Rad is sufficient to enhance basal calcium influx and contractility to adrenergically augmented levels of wild-type mice, rescuing the failing heart phenotype of 4SA-Rad mice. Hence, disruption of interactions between Rad and calcium channels constitutes the foundation toward next-generation therapeutics specifically enhancing cardiac contractility.
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Affiliation(s)
- Arianne Papa
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- These authors contributed equally: Arianne Papa, Sergey I. Zakharov, Alexander N. Katchman, Jared S. Kushner
| | - Sergey I. Zakharov
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- These authors contributed equally: Arianne Papa, Sergey I. Zakharov, Alexander N. Katchman, Jared S. Kushner
| | - Alexander N. Katchman
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- These authors contributed equally: Arianne Papa, Sergey I. Zakharov, Alexander N. Katchman, Jared S. Kushner
| | - Jared S. Kushner
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- These authors contributed equally: Arianne Papa, Sergey I. Zakharov, Alexander N. Katchman, Jared S. Kushner
| | - Bi-xing Chen
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Guoxia Liu
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Alejandro Sanchez Jimenez
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Robyn J. Eisert
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Gary A. Bradshaw
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Wen Dun
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Shah R. Ali
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Aaron Rodriques
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Karen Zhou
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Veli Topkara
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - John P. Morrow
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Emily J. Tsai
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Arthur Karlin
- Department of Biochemistry and Molecular Biophysics, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Elaine Wan
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Marian Kalocsay
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA
- Present address: Department of Experimental Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute and Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pharmacology and Molecular Signaling, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pharmacology and Molecular Signaling, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
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Multisite phosphorylation of the cardiac ryanodine receptor: a random or coordinated event? Pflugers Arch 2020; 472:1793-1807. [PMID: 33078311 DOI: 10.1007/s00424-020-02473-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/03/2020] [Accepted: 10/02/2020] [Indexed: 10/23/2022]
Abstract
Many proteins are phosphorylated at more than one phosphorylation site to achieve precise tuning of protein function and/or integrate a multitude of signals into the activity of one protein. Increasing the number of phosphorylation sites significantly broadens the complexity of molecular mechanisms involved in processing multiple phosphorylation sites by one or more distinct kinases. The cardiac ryanodine receptor (RYR2) is a well-established multiple phospho-target of kinases activated in response to β-adrenergic stimulation because this Ca2+ channel is a critical component of Ca2+ handling machinery which is responsible for β-adrenergic enhancement of cardiac contractility. Our review presents a selective overview of the extensive, often conflicting, literature which focuses on identifying reliable lines of evidence to establish if multiple RYR2 phosphorylation is achieved randomly or in a specific sequence, and whether phosphorylation at individual sites is functionally specific and additive or similar and can therefore be substituted.
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Mei L, Zheng YM, Song T, Yadav VR, Joseph LC, Truong L, Kandhi S, Barroso MM, Takeshima H, Judson MA, Wang YX. Rieske iron-sulfur protein induces FKBP12.6/RyR2 complex remodeling and subsequent pulmonary hypertension through NF-κB/cyclin D1 pathway. Nat Commun 2020; 11:3527. [PMID: 32669538 PMCID: PMC7363799 DOI: 10.1038/s41467-020-17314-1] [Citation(s) in RCA: 12] [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: 06/01/2019] [Accepted: 06/17/2020] [Indexed: 02/07/2023] Open
Abstract
Ca2+ signaling in pulmonary arterial smooth muscle cells (PASMCs) plays an important role in pulmonary hypertension (PH). However, the underlying specific ion channel mechanisms remain largely unknown. Here, we report ryanodine receptor (RyR) channel activity and Ca2+ release both are increased, and association of RyR2 by FK506 binding protein 12.6 (FKBP12.6) is decreased in PASMCs from mice with chronic hypoxia (CH)-induced PH. Smooth muscle cell (SMC)-specific RyR2 knockout (KO) or Rieske iron-sulfur protein (RISP) knockdown inhibits the altered Ca2+ signaling, increased nuclear factor (NF)-κB/cyclin D1 activation and cell proliferation, and CH-induced PH in mice. FKBP12.6 KO or FK506 treatment enhances CH-induced PH, while S107 (a specific stabilizer of RyR2/FKBP12.6 complex) produces an opposite effect. In conclusion, CH causes RISP-dependent ROS generation and FKBP12.6/RyR2 dissociation, leading to PH. RISP inhibition, RyR2/FKBP12.6 complex stabilization and Ca2+ release blockade may be potentially beneficial for the treatment of PH.
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Affiliation(s)
- Lin Mei
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Tengyao Song
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Vishal R Yadav
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Leroy C Joseph
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Lillian Truong
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Sharath Kandhi
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Margarida M Barroso
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan
| | - Marc A Judson
- Division of Pulmonary and Critical Care Medicine, Albany Medical College, Albany, 12208, NY, USA
| | - Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, 12208, NY, USA.
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6
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Abstract
There has been a significant progress in our understanding of the molecular mechanisms by which calcium (Ca2+) ions mediate various types of cardiac arrhythmias. A growing list of inherited gene defects can cause potentially lethal cardiac arrhythmia syndromes, including catecholaminergic polymorphic ventricular tachycardia, congenital long QT syndrome, and hypertrophic cardiomyopathy. In addition, acquired deficits of multiple Ca2+-handling proteins can contribute to the pathogenesis of arrhythmias in patients with various types of heart disease. In this review article, we will first review the key role of Ca2+ in normal cardiac function-in particular, excitation-contraction coupling and normal electric rhythms. The functional involvement of Ca2+ in distinct arrhythmia mechanisms will be discussed, followed by various inherited arrhythmia syndromes caused by mutations in Ca2+-handling proteins. Finally, we will discuss how changes in the expression of regulation of Ca2+ channels and transporters can cause acquired arrhythmias, and how these mechanisms might be targeted for therapeutic purposes.
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Affiliation(s)
- Andrew P Landstrom
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Dobromir Dobrev
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Xander H T Wehrens
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.).
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7
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Walweel K, Molenaar P, Imtiaz MS, Denniss A, Dos Remedios C, van Helden DF, Dulhunty AF, Laver DR, Beard NA. Ryanodine receptor modification and regulation by intracellular Ca 2+ and Mg 2+ in healthy and failing human hearts. J Mol Cell Cardiol 2017; 104:53-62. [PMID: 28131631 DOI: 10.1016/j.yjmcc.2017.01.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/01/2017] [Accepted: 01/24/2017] [Indexed: 11/30/2022]
Abstract
RATIONALE Heart failure is a multimodal disorder, of which disrupted Ca2+ homeostasis is a hallmark. Central to Ca2+ homeostasis is the major cardiac Ca2+ release channel - the ryanodine receptor (RyR2) - whose activity is influenced by associated proteins, covalent modification and by Ca2+ and Mg2+. That RyR2 is remodelled and its function disturbed in heart failure is well recognized, but poorly understood. OBJECTIVE To assess Ca2+ and Mg2+ regulation of RyR2 from left ventricles of healthy, cystic fibrosis and failing hearts, and to correlate these functional changes with RyR2 modifications and remodelling. METHODS AND RESULTS The function of RyR2 from left ventricular samples was assessed using lipid bilayer single-channel measurements, whilst RyR2 modification and protein:protein interactions were determined using Western Blots and co-immunoprecipitation. In all failing hearts there was an increase in RyR2 activity at end-diastolic cytoplasmic Ca2+ (100nM), a decreased cytoplasmic [Ca2+] required for half maximal activation (Ka) and a decrease in inhibition by cytoplasmic Mg2+. This was accompanied by significant hyperphosphorylation of RyR2 S2808 and S2814, reduced free thiol content and a reduced interaction with FKBP12.0 and FKBP12.6. Either dephosphorylation of RyR2 using PP1 or thiol reduction using DTT eliminated any significant difference in the activity of RyR2 from healthy and failing hearts. We also report a subgroup of RyR2 in failing hearts that were not responsive to regulation by intracellular Ca2+ or Mg2+. CONCLUSION Despite different aetiologies, disrupted RyR2 Ca2+ sensitivity and biochemical modification of the channel are common constituents of failing heart RyR2 and may underlie the pathological disturbances in intracellular Ca2+ signalling.
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Affiliation(s)
- K Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - P Molenaar
- Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, 4000, Northside Clinical School, School of Clinical Medicine, University of Queensland and Critical Care Research Group, The Prince Charles Hospital, Chermside, QLD, 4032, Australia
| | - M S Imtiaz
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - A Denniss
- Health Research Institute, Faculty of Education Science and Mathematics, University of Canberra, Bruce, ACT 2617, Australia
| | - C Dos Remedios
- Bosch Institute, Discipline of Anatomy, University of Sydney, Sydney, New South Wales 2006, Australia
| | - D F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - A F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, ACT, 0200, Australia
| | - D R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - N A Beard
- Health Research Institute, Faculty of Education Science and Mathematics, University of Canberra, Bruce, ACT 2617, Australia; John Curtin School of Medical Research, Australian National University, Canberra, ACT, 0200, Australia.
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8
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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9
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Quick AP, Wang Q, Philippen LE, Barreto-Torres G, Chiang DY, Beavers D, Wang G, Khalid M, Reynolds JO, Campbell HM, Showell J, McCauley MD, Scholten A, Wehrens XHT. SPEG (Striated Muscle Preferentially Expressed Protein Kinase) Is Essential for Cardiac Function by Regulating Junctional Membrane Complex Activity. Circ Res 2016; 120:110-119. [PMID: 27729468 DOI: 10.1161/circresaha.116.309977] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/04/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022]
Abstract
RATIONALE Junctional membrane complexes (JMCs) in myocytes are critical microdomains, in which excitation-contraction coupling occurs. Structural and functional disruption of JMCs underlies contractile dysfunction in failing hearts. However, the role of newly identified JMC protein SPEG (striated muscle preferentially expressed protein kinase) remains unclear. OBJECTIVE To determine the role of SPEG in healthy and failing adult hearts. METHODS AND RESULTS Proteomic analysis of immunoprecipitated JMC proteins ryanodine receptor type 2 and junctophilin-2 (JPH2) followed by mass spectrometry identified the serine-threonine kinase SPEG as the only novel binding partner for both proteins. Real-time polymerase chain reaction revealed the downregulation of SPEG mRNA levels in failing human hearts. A novel cardiac myocyte-specific Speg conditional knockout (MCM-Spegfl/fl) model revealed that adult-onset SPEG deficiency results in heart failure (HF). Calcium (Ca2+) and transverse-tubule imaging of ventricular myocytes from MCM-Spegfl/fl mice post HF revealed both increased sarcoplasmic reticulum Ca2+ spark frequency and disrupted JMC integrity. Additional studies revealed that transverse-tubule disruption precedes the development of HF development in MCM-Spegfl/fl mice. Although total JPH2 levels were unaltered, JPH2 phosphorylation levels were found to be reduced in MCM-Spegfl/fl mice, suggesting that loss of SPEG phosphorylation of JPH2 led to transverse-tubule disruption, a precursor of HF development in SPEG-deficient mice. CONCLUSIONS The novel JMC protein SPEG is downregulated in human failing hearts. Acute loss of SPEG in mouse hearts causes JPH2 dephosphorylation and transverse-tubule loss associated with downstream Ca2+ mishandling leading to HF. Our study suggests that SPEG could be a novel target for the treatment of HF.
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Affiliation(s)
- Ann P Quick
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Qiongling Wang
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Leonne E Philippen
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Giselle Barreto-Torres
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - David Y Chiang
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - David Beavers
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Guoliang Wang
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Maha Khalid
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Julia O Reynolds
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Hannah M Campbell
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Jordan Showell
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Mark D McCauley
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Arjen Scholten
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.)
| | - Xander H T Wehrens
- From the Department of Molecular Physiology and Biophysics (A.P.Q., Q.W., L.E.P., G.B.-T., J.O.R., H.M.C., J.S., X.H.T.W), Cardiovascular Research Institute (A.P.Q., Q.W., L.E.P., G.B.-T., D.Y.C., D.B., G.W., J.O.R., H.M.C., J.S., M.D.M., X.H.T.W), Medical Scientist Training Program (D.Y.C., D.B., H.M.C.), Department of Medicine (Cardiology) (M.D.M., X.H.T.W), and Pediatrics (X.H.T.W.), Baylor College of Medicine, Houston, TX; Accelerated BS/MD Program, Department of Biology and Biochemistry, University of Houston, TX (M.K.); and Department of Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (A.S.).
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10
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Backx PH. Complexity, confusion and controversy continue complicating the contribution of RyR2 channel phosphorylation to heart function. J Physiol 2015; 592:1911-2. [PMID: 24786150 DOI: 10.1113/jphysiol.2014.272575] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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11
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Fares E, Pyle WG, Ray G, Rose RA, Denovan-Wright EM, Chen RP, Howlett SE. The impact of ovariectomy on calcium homeostasis and myofilament calcium sensitivity in the aging mouse heart. PLoS One 2013; 8:e74719. [PMID: 24058623 PMCID: PMC3776741 DOI: 10.1371/journal.pone.0074719] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/05/2013] [Indexed: 12/20/2022] Open
Abstract
This study determined whether deficiency of ovarian estrogen starting very early in life promoted age-associated Ca(2+) dysregulation and contractile dysfunction in isolated ventricular myocytes. Myocytes were isolated from anesthetized C57BL/6 female mice. Animals received an ovariectomy or sham-operation at one month and were aged to ~24 months. Excitation-contraction coupling parameters were compared in fura-2 loaded myocytes (37°C). While Ca(2+) transients were larger and faster in field-stimulated myocytes from ovariectomized mice, ovariectomy had no effect on peak fractional shortening. Similarly, ovariectomy had no effect on fractional shortening measured in vivo by echocardiography (values were 60.5 ± 2.9 vs. 60.3 ± 2.5% in sham and ovariectomized, respectively; n=5 mice/group). Ovariectomy did decrease myofilament Ca(2+) sensitivity, as evidenced by a 26% increase in the Ca(2+) required to activate actomyosin MgATPase in ovariectomized hearts. Larger Ca(2+) transients were attributable to a 48% increase in peak Ca(2+) current, along with an increase in the amplitude, width and frequency of Ca(2+) sparks measured in fluo-4 loaded myocytes. These changes in Ca(2+) handling were not due to increased expression of Ca(2+) channels (Cav1.2), sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) or Na(+)-Ca(2+) exchanger in ovariectomized hearts. However, ovariectomy increased sarcoplasmic reticulum Ca(2+) stores by ~90% and promoted spontaneous Ca(2+) release from the sarcoplasmic reticulum when compared to sham controls. These observations demonstrate that long-term ovariectomy promotes intracellular Ca(2+) dysregulation, reduces myofilament Ca(2+) sensitivity and increases spontaneous Ca(2+) release in the aging female heart.
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Affiliation(s)
- Elias Fares
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W. Glen Pyle
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Gibanananda Ray
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert A. Rose
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - Robert P. Chen
- Pediatric Cardiology, IWK Health Centre and Dalhousie University, Halifax, Nova Scotia, Canada
| | - Susan E. Howlett
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
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12
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Fauconnier J, Roberge S, Saint N, Lacampagne A. Type 2 ryanodine receptor: A novel therapeutic target in myocardial ischemia/reperfusion. Pharmacol Ther 2013; 138:323-32. [DOI: 10.1016/j.pharmthera.2013.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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13
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Domeier TL, Maxwell JT, Blatter LA. β-Adrenergic stimulation increases the intra-sarcoplasmic reticulum Ca2+ threshold for Ca2+ wave generation. J Physiol 2012; 590:6093-108. [PMID: 22988136 DOI: 10.1113/jphysiol.2012.236117] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
β-Adrenergic signalling induces positive inotropic effects on the heart that associate with pro-arrhythmic spontaneous Ca(2+) waves. A threshold level of sarcoplasmic reticulum (SR) Ca(2+) ([Ca(2+)](SR)) is necessary to trigger Ca(2+) waves, and whether the increased incidence of Ca(2+) waves during β-adrenergic stimulation is due to an alteration in this threshold remains controversial. Using the low-affinity Ca(2+) indicator fluo-5N entrapped within the SR of rabbit ventricular myocytes, we addressed this controversy by directly monitoring [Ca(2+)](SR) and Ca(2+) waves during β-adrenergic stimulation. Electrical pacing in elevated extracellular Ca(2+) ([Ca(2+)](o) = 7 mM) was used to increase [Ca(2+)](SR) to the threshold where Ca(2+) waves were consistently observed. The β-adrenergic agonist isoproterenol (ISO; 1 μM) increased [Ca(2+)](SR) well above the control threshold and consistently triggered Ca(2+) waves. However, when [Ca(2+)](SR) was subsequently lowered in the presence of ISO (by lowering [Ca(2+)](o) to 1 mM and partially inhibiting sarcoplasmic/endoplasmic reticulum calcium ATPase with cyclopiazonic acid or thapsigargin), Ca(2+) waves ceased to occur at a [Ca(2+)](SR) that was higher than the control threshold. Furthermore, for a set [Ca(2+)](SR) level the refractoriness of wave occurrence (Ca(2+) wave latency) was prolonged during β-adrenergic stimulation, and was highly dependent on the extent that [Ca](SR) exceeded the wave threshold. These data show that acute β-adrenergic stimulation increases the [Ca(2+)](SR) threshold for Ca(2+) waves, and therefore the primary cause of Ca(2+) waves is the robust increase in [Ca(2+)](SR) above this higher threshold level. Elevation of the [Ca(2+)](SR) wave threshold and prolongation of wave latency represent potentially protective mechanisms against pro-arrhythmogenic Ca(2+) release during β-adrenergic stimulation.
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Affiliation(s)
- Timothy L Domeier
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL 60612, USA
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14
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Florea SM, Blatter LA. Regulation of cardiac alternans by β-adrenergic signaling pathways. Am J Physiol Heart Circ Physiol 2012; 303:H1047-56. [PMID: 22904161 DOI: 10.1152/ajpheart.00384.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In cat atrial myocytes, β-adrenergic receptor (β-AR) stimulation exerts profound effects on excitation-contraction coupling and cellular Ca(2+) cycling that are mediated by β(1)- and β(2)-AR subtypes coupled to G proteins (G(s) and G(i)). In this study, we determined the effects of β-AR stimulation on pacing-induced Ca(2+) alternans. Ca(2+) alternans was recorded from single cat atrial myocytes with the fluorescent Ca(2+) indicator indo-1. Stable Ca(2+) alternans occurred at an average pacing frequency of 1.7 Hz at room temperature with a mean alternans ratio of 0.43. Nonselective β-AR stimulation as well as selective stimulation of β(1)/G(s), β(2)/G(s) + G(i), and β(2)/G(s) coupled pathways all abolished pacing-induced Ca(2+) alternans. β(1)-AR stimulation abolished alternans through stimulation of PKA and Ca(2+)/calmodulin-dependent protein kinase II, whereas β(2)-AR stimulation exclusively involved PKA and was mediated via G(s), whereas a known second pathway in cat atrial myocytes acting through G(i) and nitric oxide production was not involved in alternans regulation. Inhibition of various mitochondrial functions (dissipation of the mitochondrial membrane potential or inhibition of mitochondrial F(1)/F(0)-ATP synthase, mitochondrial Ca(2+) uptake via the mitochondrial Ca(2+) uniporter, and Ca(2+) extrusion via mitochondrial Na(+)/Ca(2+) exchange) enhanced Ca(2+) alternans; however, β-AR stimulation still abrogated alternans, provided that sufficient cellular ATP was available. Selective inhibition of mitochondrial or glycolytic ATP production did not prevent β-AR stimulation from abolishing Ca(2+) alternans. However, when both ATP sources were depleted, β-AR stimulation failed to decrease Ca(2+) alternans. These results indicate that in atrial myocytes, β-AR stimulation protects against pacing-induced alternans by acting through parallel and complementary signaling pathways.
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Affiliation(s)
- Stela M Florea
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois 60612, USA
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15
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George CH, Parthimos D, Silvester NC. A network-oriented perspective on cardiac calcium signaling. Am J Physiol Cell Physiol 2012; 303:C897-910. [PMID: 22843795 DOI: 10.1152/ajpcell.00388.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The normal contractile, electrical, and energetic function of the heart depends on the synchronization of biological oscillators and signal integrators that make up cellular signaling networks. In this review we interpret experimental data from molecular, cellular, and transgenic models of cardiac signaling behavior in the context of established concepts in cell network architecture and organization. Focusing on the cellular Ca(2+) handling machinery, we describe how the plasticity and adaptability of normal Ca(2+) signaling is dependent on dynamic network configurations that operate across a wide range of functional states. We consider how (mal)adaptive changes in signaling pathways restrict the dynamic range of the network such that it cannot respond appropriately to physiologic stimuli or perturbation. Based on these concepts, a model is proposed in which pathologic abnormalities in cardiac rhythm and contractility (e.g., arrhythmias and heart failure) arise as a consequence of progressive desynchronization and reduction in the dynamic range of the Ca(2+) signaling network. We discuss how a systems-level understanding of the network organization, cellular noise, and chaotic behavior may inform the design of new therapeutic modalities that prevent or reverse the disease-linked unraveling of the Ca(2+) signaling network.
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Affiliation(s)
- Christopher H George
- Wales Heart Research Institute and Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff Univ., Heath Park, Cardiff, Wales, UK CF14 4XN.
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16
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Haizlip KM, Janssen PML. In vitro studies of early cardiac remodeling: impact on contraction and calcium handling. Front Biosci (Schol Ed) 2011; 3:1047-57. [PMID: 21622254 DOI: 10.2741/209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cardiac remodeling, hypertrophy, and alterations in calcium signaling are changes of the heart that often lead to failure. After a hypertrophic stimulus, the heart progresses through a state of compensated hypertrophy which over time leads to decompensated hypertrophy or failure. It is at this point that a cardiac transplant is required for survival making early detection imperative. Current experimental systems used to study the remodeling of the heart include in vivo systems (the whole body), isolated organ and sub-organ tissue, and the individual cardiac muscle cells and organelles.. During pathological remodeling there is a derangement in the intracellular calcium handling processes. These derangements are thought to lead to a dysregulation of contractile output. Hence, understanding the mechanism between remodeling and dysregulation is of great interest in the cardiac field and will ultimately help in the development of future treatment and early detection. This review will center on changes in contraction and calcium handling in early cardiac remodeling, with a specific focus on findings in two different in vitro model systems: multicellular and individual cell preparations.
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Affiliation(s)
- Kaylan M Haizlip
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210-1218, USA
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