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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Ca2+ signalling, we generated double knock-in (DKI) mice in which Ser2808 and Ser2814 phosphorylation sites have both been replaced by alanine (RyR2-S2808A/S2814A).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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2
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Zheng J, Dooge HC, Valdivia HH, Alvarado FJ. Ablation of three major phospho-sites in RyR2 preserves the global adrenergic response but creates an arrhythmogenic substrate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.602617. [PMID: 39026734 PMCID: PMC11257526 DOI: 10.1101/2024.07.08.602617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Background Ryanodine receptor 2 (RyR2) is one of the first substrates undergoing phosphorylation upon catecholaminergic stimulation. Yet, the role of RyR2 phosphorylation in the adrenergic response remains debated. To date, three residues in RyR2 are known to undergo phosphorylation upon adrenergic stimulation. We generated a model of RyR2 phospho-ablation of all three canonical phospho-sites (RyR2-S2031A/S2808A/S2814A, triple phospho-mutant, TPM) to elucidate the role of phosphorylation at these residues in the adrenergic response. Methods Cardiac structure and function, cellular Ca 2+ dynamics and electrophysiology, and RyR2 channel activity both under basal conditions and under isoproterenol (Iso) stimulation were systematically evaluated. We used echocardiography and electrocardiography in anesthetized mice, single-cell Ca 2+ imaging and whole-cell patch clamp in isolated adult cardiomyocytes, and biochemical assays. Results Iso stimulation produced normal chronotropic and inotropic responses in TPM mice as well as an increase in the global Ca 2+ transients in isolated cardiomyocytes. Functional studies revealed fewer Ca 2+ sparks in permeabilized TPM myocytes, and reduced RyR2-mediated Ca 2+ leak in intact myocytes under Iso stimulation, suggesting that the canonical sites may regulate RyR2-mediated Ca 2+ leak. TPM mice also displayed increased propensity for arrhythmia. TPM myocytes were prone to develop early afterdepolarizations (EADs), which were abolished by chelating intracellular Ca 2+ with EGTA, indicating that EADs require SR Ca 2+ release. EADs were also blocked by a low concentration of tetrodotoxin, further suggesting reactivation of the sodium current ( I Na ) as the underlying cause. Conclusion Phosphorylation of the three canonical residues on RyR2 may not be essential for the global adrenergic responses. However, these sites play a vital role in maintaining electrical stability during catecholamine stimulation by fine-tuning RyR2-mediated Ca 2+ leak. These findings underscore the importance of RyR2 phosphorylation and a finite diastolic Ca 2+ leak in maintaining electrical stability during catecholamine stimulation.
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Asghari P, Scriven DR, Shahrasebi S, Valdivia HH, Alsina KM, Valdivia CR, Navarro-Garcia JA, Wehrens XH, Moore ED. Phosphorylation of RyR2 simultaneously expands the dyad and rearranges the tetramers. J Gen Physiol 2024; 156:e202213108. [PMID: 38385988 PMCID: PMC10883851 DOI: 10.1085/jgp.202213108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 01/23/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
We have previously demonstrated that type II ryanodine receptors (RyR2) tetramers can be rapidly rearranged in response to a phosphorylation cocktail. The cocktail modified downstream targets indiscriminately, making it impossible to determine whether phosphorylation of RyR2 was an essential element of the response. Here, we used the β-agonist isoproterenol and mice homozygous for one of the following clinically relevant mutations: S2030A, S2808A, S2814A, or S2814D. We measured the length of the dyad using transmission electron microscopy (TEM) and directly visualized RyR2 distribution using dual-tilt electron tomography. We found that the S2814D mutation, by itself, significantly expanded the dyad and reorganized the tetramers, suggesting a direct link between the phosphorylation state of the tetramer and its microarchitecture. S2808A and S2814A mutant mice, as well as wild types, had significant expansions of their dyads in response to isoproterenol, while S2030A mutants did not. In agreement with functional data from these mutants, S2030 and S2808 were necessary for a complete β-adrenergic response, unlike S2814 mutants. Additionally, all mutants had unique effects on the organization of their tetramer arrays. Lastly, the correlation of structural with functional changes suggests that tetramer-tetramer contacts play an important functional role. We thus conclude that both the size of the dyad and the arrangement of the tetramers are linked to the state of the channel tetramer and can be dynamically altered by a β-adrenergic receptor agonist.
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Affiliation(s)
- Parisa Asghari
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - David R.L. Scriven
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Saba Shahrasebi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Hector H. Valdivia
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Carmen R. Valdivia
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - J. Alberto Navarro-Garcia
- Department of Integrative Physiology, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander H.T. Wehrens
- Department of Integrative Physiology, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Edwin D.W. Moore
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
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Short B. RyR2 phosphorylation alters dyad architecture. J Gen Physiol 2024; 156:e202413569. [PMID: 38451203 PMCID: PMC10918937 DOI: 10.1085/jgp.202413569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024] Open
Abstract
JGP study (Asghari et al. 2024. J. Gen. Physiol.https://doi.org/10.1085/jgp.202213108) indicates that β-adrenergic signaling enlarges dyads and reorganizes RyR2 tetramers in cardiomyocytes.
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Affiliation(s)
- Ben Short
- Science Writer, Rockefeller University Press, New York, NY, USA
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Asghari P, Scriven DRL, Shahrasebi S, Valdivia HH, Wehrens XHT, Moore EDW. PHOSPHORYLATION OF RyR2 SIMULTANEOUSLY EXPANDS THE DYAD AND REARRANGES THE TETRAMERS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.23.541024. [PMID: 37292875 PMCID: PMC10245935 DOI: 10.1101/2023.05.23.541024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have previously demonstrated that type II ryanodine receptors (RyR2) tetramers can be rapidly rearranged in response to a phosphorylation cocktail. The cocktail modified downstream targets indiscriminately making it impossible to determine whether phosphorylation of RyR2 was an essential element of the response. We therefore used the β-agonist isoproterenol and mice with one of the homozygous mutations, S2030A +/+ , S2808A +/+ , S2814A +/+ , or S2814D +/+ , to address this question and to elucidate the role of these clinically relevant mutations. We measured the length of the dyad using transmission electron microscopy (TEM) and directly visualized RyR2 distribution using dual-tilt electron tomography. We found that: 1) The S2814D mutation, by itself, significantly expanded the dyad and reorganized the tetramers suggesting a direct link between the phosphorylation state of the tetramer and the microarchitecture. 2) All of the wild-type, as well as the S2808A and S2814A mice, had significant expansions of their dyads in response to ISO, while S2030A did not. 3) In agreement with functional data from the same mutants, S2030 and S2808 were necessary for a complete β-adrenergic response, whereas S2814 was not. 4) All the mutated residues had unique effects on the organization of their tetramer arrays. 5) The correlation of structure with function suggests that tetramer-tetramer contacts play an important functional role. We conclude that both the size of the dyad and the arrangement of the tetramers are linked to the state of the channel tetramer and can be dynamically altered by a β-adrenergic receptor agonist. Summary Analysis of RyR2 mutants suggests a direct link between the phosphorylation state of the channel tetramer and the microarchitecture of the dyad. All phosphorylation site mutations produced significant and unique effects on the structure of the dyad and its response to isoproterenol.
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Chen Y, Lu Y, Wu W, Lin Y, Chen Y, Chen S, Chen Y. Advanced glycation end products modulate electrophysiological remodeling of right ventricular outflow tract cardiomyocytes: A novel target for diabetes-related ventricular arrhythmogenesis. Physiol Rep 2022; 10:e15499. [PMID: 36325589 PMCID: PMC9630757 DOI: 10.14814/phy2.15499] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 09/11/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023] Open
Abstract
Diabetes mellitus is associated with cardiovascular disease and cardiac arrhythmia. Accumulation of advanced glycation end products closely correlates with cardiovascular complications through mitochondrial dysfunction or oxidative stress and evoke proliferative, inflammatory, and fibrotic reactions, which might impair cardiac electrophysiological characteristics and increase the incidence of cardiac arrhythmia. This study examined the mechanisms how advanced glycation end products may contribute to arrhythmogenesis of right ventricular outflow tract-a unique arrhythmogenic substrate. A whole-cell patch clamp, conventional electrophysiological study, fluorescence imaging, Western blot, and confocal microscope were used to study the electrical activity, and Ca2+ homeostasis or signaling in isolated right ventricular outflow tract myocytes with and without advanced glycation end products (100 μg/ml). The advanced glycation end products treated right ventricular outflow tract myocytes had a similar action potential duration as the controls, but exhibited a lower L-type Ca2+ current, higher late sodium current and transient outward current. Moreover, the advanced glycation end products treated right ventricular outflow tract myocytes had more intracellular Na+ , reverse mode Na+ -Ca2+ exchanger currents, intracellular and mitochondrial reactive oxygen species, and less intracellular Ca2+ transient and sarcoplasmic reticulum Ca2+ content with upregulated calcium homeostasis proteins and advanced glycation end products related signaling pathway proteins. In conclusions, advanced glycation end products modulate right ventricular outflow tract electrophysiological characteristics with larger late sodium current, intracellular Na+ , reverse mode Na+ -Ca2+ exchanger currents, and disturbed Ca2+ homeostasis through increased oxidative stress mediated by the activation of the advanced glycation end products signaling pathway.
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Affiliation(s)
- Yao‐Chang Chen
- Department of Biomedical EngineeringNational Defense Medical CenterTaipeiTaiwan
| | - Yen‐Yu Lu
- Division of CardiologySijhih Cathay General HospitalNew Taipei CityTaiwan
- School of Medicine, College of MedicineFu Jen Catholic UniversityNew Taipei CityTaiwan
| | - Wen‐Shiann Wu
- Department of CardiologyChi‐Mei Medical CenterTainanTaiwan
| | - Yung‐Kuo Lin
- Taipei Heart Institute, Taipei Medical UniversityTaipeiTaiwan
- Division of Cardiovascular Medicine, Department of Internal MedicineWan Fang Hospital, Taipei Medical UniversityTaipeiTaiwan
- Division of Cardiology, Department of Internal Medicine, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Yi‐Ann Chen
- Division of CardiologySijhih Cathay General HospitalNew Taipei CityTaiwan
- Division of NephrologySijhih Cathay General HospitalNew Taipei CityTaiwan
| | - Shih‐Ann Chen
- Heart Rhythm Center, Division of Cardiology, Department of MedicineTaipei Veterans General HospitalTaipeiTaiwan
- Cardiovascular Center, Taichung Veterans General HospitalTaichungTaiwan
- Department of Post‐Baccalaureate Medicine, College of MedicineNational Chung Hsing UniversityTaichungTaiwan
| | - Yi‐Jen Chen
- Taipei Heart Institute, Taipei Medical UniversityTaipeiTaiwan
- Division of Cardiovascular Medicine, Department of Internal MedicineWan Fang Hospital, Taipei Medical UniversityTaipeiTaiwan
- Graduate Institute of Clinical Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
- Cardiovascular Research CenterWan Fang Hospital, Taipei Medical UniversityTaipeiTaiwan
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Regulation of cardiac ryanodine receptor function by the cyclic-GMP dependent protein kinase G. Curr Res Physiol 2022; 5:171-178. [PMID: 35356048 PMCID: PMC8958330 DOI: 10.1016/j.crphys.2022.03.004] [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: 11/08/2021] [Revised: 02/20/2022] [Accepted: 03/21/2022] [Indexed: 11/21/2022] Open
Abstract
Background The cGMP-dependent protein kinase G (PKG) phosphorylates the cardiac ryanodine receptor (RyR2) in vitro. We aimed to determine whether modulation of endogenous PKG alters RyR2-mediated spontaneous Ca2+ release and whether this effect is linked to a change in RyR2 phosphorylation. Methods & Results: Human embryonic kidney (HEK293) cells with inducible RyR2 expression were treated with the cGMP analogue 8-Br-cGMP (100 μM) to activate endogenous PKG. In cells transfected with luminal Ca2+ sensor, D1ER, PKG activation significantly reduced the threshold for RyR2-mediated spontaneous Ca2+ release (93.9 ± 0.4% of store size with vehicle vs. 91.7 ± 0.8% with 8-Br-cGMP, P = 0.04). Mutation of the proposed PKG phosphorylation sites, S2808 and S2030, either individually or as a combination, prevented the decrease in Ca2+ release threshold induced by endogenous PKG activation. Interestingly, despite a functional dependence on expression of RyR2 phosphorylation sites, 8-Br-cGMP activation of PKG did not promote a detectable change in S2808 phosphorylation (P = 0.9). Paradoxically, pharmacological inhibition of PKG with KT 5823 (1 μM) also reduced the threshold for spontaneous Ca2+ release through RyR2 without affecting S2808 phosphorylation. Silencing RNA knockdown of endogenous PKG expression also had no quantifiable effect on RyR2 S2808 phosphorylation (P = 0.9). However, unlike PKG inhibition with KT 5823, PKG knockdown did not alter spontaneous Ca2+ release propensity or luminal Ca2+ handling. Conclusion In an intact cell model, activation of endogenous PKG reduces the threshold for RyR2-mediated spontaneous Ca2+ release in a manner dependent on the RyR2 phosphorylation sites S2808 and S2030. This study clarifies the regulation of RyR2 Ca2+ release by endogenous PKG and functionally implicates the role of RyR2 phosphorylation. PKG regulation of RyR2 has been under-researched relative to other kinases. Endogenous PKG activation reduced the threshold for spontaneous RyR2 Ca2+ release. Regulation of RyR2 by PKG required expression of serine residues 2808 and 2030. Knockdown of PKG found minimal basal regulation of RyR2 by PKG.
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Kobayashi T, Kurebayashi N, Murayama T. The Ryanodine Receptor as a Sensor for Intracellular Environments in Muscles. Int J Mol Sci 2021; 22:ijms221910795. [PMID: 34639137 PMCID: PMC8509754 DOI: 10.3390/ijms221910795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 01/12/2023] Open
Abstract
The ryanodine receptor (RyR) is a Ca2+ release channel in the sarcoplasmic reticulum of skeletal and cardiac muscles and plays a key role in excitation-contraction coupling. The activity of the RyR is regulated by the changes in the level of many intracellular factors, such as divalent cations (Ca2+ and Mg2+), nucleotides, associated proteins, and reactive oxygen species. Since these intracellular factors change depending on the condition of the muscle, e.g., exercise, fatigue, or disease states, the RyR channel activity will be altered accordingly. In this review, we describe how the RyR channel is regulated under various conditions and discuss the possibility that the RyR acts as a sensor for changes in the intracellular environments in muscles.
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Körner A, Mosqueira M, Hecker M, Ullrich ND. Substrate Stiffness Influences Structural and Functional Remodeling in Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Front Physiol 2021; 12:710619. [PMID: 34489730 PMCID: PMC8416903 DOI: 10.3389/fphys.2021.710619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Novel treatment strategies for cardiac tissue regeneration are heading for the use of engineered cardiac tissue made from induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Despite the proven cardiogenic phenotype of these cells, a significant lack of structural and functional properties of mature myocytes prevents safe integration into the diseased heart. To date, maturation processes of cardiomyocytes remain largely unknown but may comprise biophysical cues from the immediate cell environment. Mechanosensing is one critical ability of cells to react to environmental changes. Accordingly, the surrounding substrate stiffness, comprised of extracellular matrix (ECM), cells, and growth surface, critically influences the myocyte's physiology, as known from deleterious remodeling processes in fibrotic hearts. Conversely, the mechanical properties during culture of iPSC-CMs may impact on their structural and functional maturation. Here, we tested the hypothesis that the environmental stiffness influences structural and functional properties of iPSC-CMs and investigated the effect of different substrate stiffnesses on cell contractility, excitation-contraction (EC) coupling, and intercellular coupling. Culture surfaces with defined stiffnesses ranging from rigid glass with 25GPa to PDMS of physiological softness were coated with ECM proteins and seeded with murine iPSC-CMs. Using confocal imaging, cardiac protein expression was assessed. Ca2+ handling and contractile properties were analyzed on different substrate stiffnesses. Intercellular coupling via gap junctions was investigated by fluorescence recovery after photobleaching (FRAP). Our data revealed greater organization of L-type Ca2+ channels and ryanodine receptors and increased EC-coupling gain, demonstrating structural and functional maturation in cells grown on soft surfaces. In addition, increased shortening and altered contraction dynamics revealed increased myofilament Ca2+ sensitivity in phase-plane loops. Moreover, connexin 43 expression was significantly increased in iPSC-CMs grown on soft surfaces leading to improved intercellular coupling. Taken together, our results demonstrate that soft surfaces with stiffnesses in the physiological range improve the expression pattern and interaction of cardiac proteins relevant for EC-coupling. In parallel, soft substrates influence contractile properties and improve intercellular coupling in iPSC-CMs. We conclude that the mechanical stiffness of the cell environment plays an important role in driving iPSC-CMs toward further maturation by inducing adaptive responses.
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Affiliation(s)
- Arlene Körner
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg-Mannheim, Heidelberg, Germany
| | - Matias Mosqueira
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Markus Hecker
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg-Mannheim, Heidelberg, Germany
| | - Nina D Ullrich
- Division of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg-Mannheim, Heidelberg, Germany
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10
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Racioppi MF, Burgos JI, Morell M, Gonano LA, Vila Petroff M. Cellular Mechanisms Underlying the Low Cardiotoxicity of Istaroxime. J Am Heart Assoc 2021; 10:e018833. [PMID: 34219467 PMCID: PMC8483492 DOI: 10.1161/jaha.120.018833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Istaroxime is an inhibitor of Na+/K+ ATPase with proven efficacy to increase cardiac contractility and to accelerate relaxation attributable to a relief in phospholamban‐dependent inhibition of the sarcoplasmic reticulum Ca2+ ATPase. We have previously shown that pharmacologic Na+/K+ ATPase inhibition promotes calcium/calmodulin‐dependent kinase II activation, which mediates both cardiomyocyte death and arrhythmias. Here, we aim to compare the cardiotoxic effects promoted by classic pharmacologic Na+/K+ ATPase inhibition versus istaroxime. Methods and Results Ventricular cardiomyocytes were treated with ouabain or istaroxime at previously tested equi‐inotropic concentrations to compare their impact on cell viability, apoptosis, and calcium/calmodulin‐dependent kinase II activation. In contrast to ouabain, istaroxime neither promoted calcium/calmodulin‐dependent kinase II activation nor cardiomyocyte death. In addition, we explored the differential behavior promoted by ouabain and istaroxime on spontaneous diastolic Ca2+ release. In rat cardiomyocytes, istaroxime did not significantly increase Ca2+ spark and wave frequency but increased the proportion of aborted Ca2+ waves. Further insight was provided by studying cardiomyocytes from mice that do not express phospholamban. In this model, the lower Ca2+ wave incidence observed with istaroxime remains present, suggesting that istaroxime‐dependent relief on phospholamban‐dependent sarcoplasmic reticulum Ca2+ ATPase 2A inhibition is not the unique mechanism underlying the low arrhythmogenic profile of this drug. Conclusions Our results indicate that, different from ouabain, istaroxime can reach a significant inotropic effect without leading to calcium/calmodulin‐dependent kinase II–dependent cardiomyocyte death. Additionally, we provide novel insights regarding the low arrhythmogenic impact of istaroxime on cardiac Ca2+ handling.
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Affiliation(s)
- María Florencia Racioppi
- Centro de Investigaciones Cardiovasculares Horacio Cingolani CONICET La Plata Facultad de Ciencias Médicas Universidad Nacional de La Plata Argentina
| | - Juan Ignacio Burgos
- Centro de Investigaciones Cardiovasculares Horacio Cingolani CONICET La Plata Facultad de Ciencias Médicas Universidad Nacional de La Plata Argentina
| | - Malena Morell
- Centro de Investigaciones Cardiovasculares Horacio Cingolani CONICET La Plata Facultad de Ciencias Médicas Universidad Nacional de La Plata Argentina
| | - Luis Alberto Gonano
- Centro de Investigaciones Cardiovasculares Horacio Cingolani CONICET La Plata Facultad de Ciencias Médicas Universidad Nacional de La Plata Argentina
| | - Martín Vila Petroff
- Centro de Investigaciones Cardiovasculares Horacio Cingolani CONICET La Plata Facultad de Ciencias Médicas Universidad Nacional de La Plata Argentina
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Safabakhsh S, Panwar P, Barichello S, Sangha SS, Hanson PJ, Van Petegem F, Laksman Z. THE ROLE OF PHOSPHORYLATION IN ATRIAL FIBRILLATION: A FOCUS ON MASS SPECTROMETRY APPROACHES. Cardiovasc Res 2021; 118:1205-1217. [PMID: 33744917 DOI: 10.1093/cvr/cvab095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/16/2021] [Indexed: 11/14/2022] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia worldwide. It is associated with significant increases in morbidity in the form of stroke and heart failure, and a doubling in all-cause mortality. The pathophysiology of AF is incompletely understood, and this has contributed to a lack of effective treatments and disease-modifying therapies. An important cellular process that may explain how risk factors give rise to AF includes post-translational modification (PTM) of proteins. As the most commonly occurring PTM, protein phosphorylation is especially relevant. Although many methods exist for studying protein phosphorylation, a common and highly resolute technique is mass spectrometry (MS). This review will discuss recent evidence surrounding the role of protein phosphorylation in the pathogenesis of AF. MS-based technology to study phosphorylation and uses of MS in other areas of medicine such as oncology will also be presented. Based on these data, future goals and experiments will be outlined that utilize MS technology to better understand the role of phosphorylation in AF and elucidate its role in AF pathophysiology. This may ultimately allow for the development of more effective AF therapies.
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Affiliation(s)
- Sina Safabakhsh
- Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pankaj Panwar
- AbCellera Biologicals Inc., Vancouver, British Columbia, Canada
| | - Scott Barichello
- Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sarabjit S Sangha
- Cellular and Regenerative Medicine Centre, BC Children's Hospital Research Institute, 950 West 28th Avenue, Vancouver, British Columbia, Canada.,Molecular Cardiac Physiology Group, Departments of Biomedical Physiology and Kinesiology and Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada
| | - Paul J Hanson
- UBC Heart Lung Innovation Centre, Vancouver, British Columbia, Canada.,UBC Department of Pathology and Laboratory Medicine, Vancouver, British Columbia, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Zachary Laksman
- Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Zhou X, Li A, Lin PH, Zhou J, Ma J. TRIC-A regulates intracellular Ca 2+ homeostasis in cardiomyocytes. Pflugers Arch 2021; 473:547-556. [PMID: 33474637 PMCID: PMC7940156 DOI: 10.1007/s00424-021-02513-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/14/2020] [Accepted: 01/04/2021] [Indexed: 01/26/2023]
Abstract
Trimeric intracellular cation (TRIC) channels have been identified as monovalent cation channels that are located in the ER/SR membrane. Two isoforms discovered in mammals are TRIC-A (TMEM38a) and TRIC-B (TMEM38b). TRIC-B ubiquitously expresses in all tissues, and TRIC-B-/- mice is lethal at the neonatal stage. TRIC-A mainly expresses in excitable cells. TRIC-A-/- mice survive normally but show abnormal SR Ca2+ handling in both skeletal and cardiac muscle cells. Importantly, TRIC-A mutations have been identified in human patients with stress-induced arrhythmia. In the past decade, important discoveries have been made to understand the structure and function of TRIC channels, especially its role in regulating intracellular Ca2+ homeostasis. In this review article, we focus on the potential roles of TRIC-A in regulating cardiac function, particularly its effects on intracellular Ca2+ signaling of cardiomyocytes and discuss the current knowledge gaps.
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Affiliation(s)
- Xinyu Zhou
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA
| | - Ang Li
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, 76019, USA
| | - Pei-Hui Lin
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, 76019, USA
| | - Jianjie Ma
- Department of Surgery, The Ohio State University Columbus, Columbus, OH, 43210, USA.
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13
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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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Gilbert G, Demydenko K, Dries E, Puertas RD, Jin X, Sipido K, Roderick HL. Calcium Signaling in Cardiomyocyte Function. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035428. [PMID: 31308143 DOI: 10.1101/cshperspect.a035428] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rhythmic increases in intracellular Ca2+ concentration underlie the contractile function of the heart. These heart muscle-wide changes in intracellular Ca2+ are induced and coordinated by electrical depolarization of the cardiomyocyte sarcolemma by the action potential. Originating at the sinoatrial node, conduction of this electrical signal throughout the heart ensures synchronization of individual myocytes into an effective cardiac pump. Ca2+ signaling pathways also regulate gene expression and cardiomyocyte growth during development and in pathology. These fundamental roles of Ca2+ in the heart are illustrated by the prevalence of altered Ca2+ homeostasis in cardiovascular diseases. Indeed, heart failure (an inability of the heart to support hemodynamic needs), rhythmic disturbances, and inappropriate cardiac growth all share an involvement of altered Ca2+ handling. The prevalence of these pathologies, contributing to a third of all deaths in the developed world as well as to substantial morbidity makes understanding the mechanisms of Ca2+ handling and dysregulation in cardiomyocytes of great importance.
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Affiliation(s)
- Guillaume Gilbert
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Eef Dries
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Rosa Doñate Puertas
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Xin Jin
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - Karin Sipido
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, BE3000 Leuven, Belgium
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15
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Potenza DM, Janicek R, Fernandez-Tenorio M, Niggli E. Activation of endogenous protein phosphatase 1 enhances the calcium sensitivity of the ryanodine receptor type 2 in murine ventricular cardiomyocytes. J Physiol 2020; 598:1131-1150. [PMID: 31943206 DOI: 10.1113/jp278951] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/10/2020] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Increased protein phosphatase 1 (PP-1) activity has been found in end stage human heart failure. Although PP-1 has been extensively studied, a detailed understanding of its role in the excitation-contraction coupling mechanism, in normal and diseased hearts, remains elusive. The present study investigates the functional effect of the PP-1 activity on local Ca2+ release events in ventricular cardiomyocytes, by using an activating peptide (PDP3) for the stimulation of the endogenous PP-1 protein. We report that acute de-phosphorylation may increase the sensitivity of RyR2 channels to Ca2+ in situ, and that the RyR2-serine2808 phosphorylation site may mediate such a process. Our approach unmasks the functional importance of PP-1 in the regulation of RyR2 activity, suggesting a potential role in the generation of a pathophysiological sarcoplasmic reticulum Ca2+ leak in the diseased heart. ABSTRACT Changes in cardiac ryanodine receptor (RyR2) phosphorylation are considered to be important regulatory and disease related post-translational protein modifications. The extent of RyR2 phosphorylation is mainly determined by the balance of the activities of protein kinases and phosphatases, respectively. Increased protein phosphatase-1 (PP-1) activity has been observed in heart failure, although the regulatory role of this enzyme on intracellular Ca2+ handling remains poorly understood. To determine the physiological and pathophysiological significance of increased PP-1 activity, we investigated how the PP-1 catalytic subunit (PP-1c) alters Ca2+ sparks in permeabilized cardiomyocytes and we also applied a PP-1-disrupting peptide (PDP3) to specifically activate endogenous PP-1, including the one anchored on the RyR2 macromolecular complex. We compared wild-type and transgenic mice in which the usually highly phosphorylated site RyR2-S2808 has been ablated to investigate its involvement in RyR2 modulation (S2808A+/+ ). In wild-type myocytes, PP-1 increased Ca2+ spark frequency by two-fold, followed by depletion of the sarcoplasmic reticulum Ca2+ store. Similarly, PDP3 transiently increased spark frequency and decreased sarcoplasmic reticulum Ca2+ load. RyR2 Ca2+ sensitivity, which was assessed by Ca2+ spark recovery analysis, was increased in the presence of PDP3 compared to a negative control peptide. S2808A+/+ cardiomyocytes did not respond to both PP-1c and PDP3 treatment. Our results suggest an increased Ca2+ sensitivity of RyR2 upon de-phosphorylation by PP-1. Furthermore, we have confirmed the S2808 site as a target for PP-1 and as a potential link between RyR2s modulation and the cellular response.
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Affiliation(s)
| | | | | | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
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16
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Zhang Z, Fang Q, Du T, Chen G, Wang Y, Wang DW. Cardiac-Specific Caveolin-3 Overexpression Prevents Post-Myocardial Infarction Ventricular Arrhythmias by Inhibiting Ryanodine Receptor-2 Hyperphosphorylation. Cardiology 2020; 145:136-147. [PMID: 32007997 DOI: 10.1159/000505316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/05/2019] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Ventricular arrhythmia is the most important risk factor for sudden cardiac death (SCD) after acute myocardial infarction (MI) worldwide. However, the molecular mechanisms underlying these arrhythmias are complex and not completely understood. OBJECTIVE Here, we evaluated whether caveolin-3 (Cav3), the structural protein of caveolae, plays an important role in the therapeutic strategy for ventricular arrhythmias. METHODS A model of cardiac-specific overexpression of Cav3 was established to evaluate the incidence of ventricular arrhythmias after MI in mice. Ca2+ imaging was employed to detect the propensity of adult murine cardiomyocytes to generate arrhythmias, and immunoprecipitation and immunofluorescence were used to determine the relationship of proteins. Additionally, qRT-PCR and western blotting were used to detect the mRNA and protein expression. RESULTS We found that cardiac-specific overexpression of Cav3 delivered by a recombinant adeno-associated viral vector reduced the incidence of ventricular arrhythmias and SCD after MI in mice. Ca2+ imaging and western blotting revealed that overexpression of Cav3 reduced diastolic spontaneous Ca2+ waves by inhibiting the hyperphosphorylation of ryanodine receptor-2 (RyR2) at Ser2814, rather than at Ser2808, compared to in rAAV-red fluorescent protein control mice. Furthermore, we demonstrated that Cav3-regulated RYR2 hyperphosphorylation relied on plakophilin-2 in hypoxia-stimulated cultured cardiomyocytes by western blotting, immunoprecipitation, and immunofluorescence in vitro. CONCLUSIONS Our results suggested a novel role for Cav3 in the prevention of ventricular arrhythmias, thereby identifying a new target for preventing SCD after MI.
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Affiliation(s)
- Zhihao Zhang
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qin Fang
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tingyi Du
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guangzhi Chen
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China,
| | - Yan Wang
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dao Wen Wang
- Division of Cardiology, Departments of Internal Medicine and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Gholamnezhad Z, Mégarbane B, Rezaee R. Molecular Mechanisms Mediating Adaptation to Exercise. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1228:45-61. [PMID: 32342449 DOI: 10.1007/978-981-15-1792-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Several experimental and human studies documented the preventive and therapeutic effects of exercise on the normal physiological function of different body systems during aging as well as various diseases. Recent studies using cellular and molecular (biochemical, proteomics, and genomics) techniques indicated that exercise modifies intracellular and extracellular signaling and pathways. In addition, in vivo or in vitro experiments, particularly, using knockout and transgenic animals, helped to mimic physiological conditions during and after exercise. According to the findings of these studies, some important signaling pathways modulated by exercise are Ca2+-dependent calcineurin/activated nuclear factor of activated T-cells, mammalian target of rapamycin, myostatin/Smad, and AMP-activated protein kinase regulation of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha. Such modulations contribute to cell adaptation and remodeling of muscle fiber type in response to exercise. Despite great improvement in this field, there are still several unanswered questions as well as unfixed issues concerning clinical trials' biases and limitations. Nevertheless, designing multicenter standard clinical trials while considering individual variability and the exercise modality and duration will improve the perspective we have on the mechanisms mediating adaptation to exercise and final outcomes.
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Affiliation(s)
- Zahra Gholamnezhad
- Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
- Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
| | - Bruno Mégarbane
- Department of Medical and Toxicological Critical Care, Paris-Diderot University, Paris, France
| | - Ramin Rezaee
- Clinical Research Unit, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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18
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Silbernagel N, Körner A, Balitzki J, Jaggy M, Bertels S, Richter B, Hippler M, Hellwig A, Hecker M, Bastmeyer M, Ullrich ND. Shaping the heart: Structural and functional maturation of iPSC-cardiomyocytes in 3D-micro-scaffolds. Biomaterials 2020; 227:119551. [DOI: 10.1016/j.biomaterials.2019.119551] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 10/06/2019] [Accepted: 10/14/2019] [Indexed: 02/05/2023]
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Zhao J, Xu T, Zhou Y, Zhou Y, Xia Y, Li D. B-type natriuretic peptide and its role in altering Ca 2+-regulatory proteins in heart failure-mechanistic insights. Heart Fail Rev 2019; 25:861-871. [PMID: 31820203 DOI: 10.1007/s10741-019-09883-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heart failure (HF) is a worldwide disease with high levels of morbidity and mortality. The pathogenesis of HF is complicated and involves imbalances in hormone and electrolyte. B-type natriuretic peptide (BNP) has served as a biomarker of HF severity, and in recent years, it has been used to treat the disease, thanks to its cardio-protective effects, such as diuresis, natriuresis, and vasodilatation. In stage C/D HF, symptoms are severe despite elevated BNP. Disturbances in Ca2+ homeostasis are often a dominating feature of the disease, causing Ca2+-regulatory protein dysfunction, including reduced expression and activity of sarcoplasmic reticulum Ca2+-ATPase2a (SERCA2a), impaired ryanodine receptors (RYRs) function, intensive Na+-Ca2+ exchanger (NCX), and downregulation of S100A1. The relationship between natriuretic peptides (NPs) and Ca2+-regulatory proteins has been widely studied and represents important mechanisms in the etiology of HF. In this review, we present evidence that BNP may regulate Ca2+-regulatory proteins, in particular, suppressing SERCA2a and S100A1 expression. However, relationships between BNP and other Ca2+-regulatory proteins remain vague.
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Affiliation(s)
- Jiaqi Zhao
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China
| | - Tongda Xu
- Department of Cardiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China
| | - Yao Zhou
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China
| | - You Zhou
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China
| | - Yong Xia
- Department of Cardiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China.
| | - Dongye Li
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China. .,Department of Cardiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, People's Republic of China.
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20
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Zhou X, Park KH, Yamazaki D, Lin PH, Nishi M, Ma Z, Qiu L, Murayama T, Zou X, Takeshima H, Zhou J, Ma J. TRIC-A Channel Maintains Store Calcium Handling by Interacting With Type 2 Ryanodine Receptor in Cardiac Muscle. Circ Res 2019; 126:417-435. [PMID: 31805819 DOI: 10.1161/circresaha.119.316241] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
RATIONALE Trimeric intracellular cation (TRIC)-A and B are distributed to endoplasmic reticulum/sarcoplasmic reticulum intracellular Ca2+ stores. The crystal structure of TRIC has been determined, confirming the homotrimeric structure of a potassium channel. While the pore architectures of TRIC-A and TRIC-B are conserved, the carboxyl-terminal tail (CTT) domains of TRIC-A and TRIC-B are different from each other. Aside from its recognized role as a counterion channel that participates in excitation-contraction coupling of striated muscles, the physiological function of TRIC-A in heart physiology and disease has remained largely unexplored. OBJECTIVE In cardiomyocytes, spontaneous Ca2+ waves, triggered by store overload-induced Ca2+ release mediated by the RyR2 (type 2 ryanodine receptor), develop extrasystolic contractions often associated with arrhythmic events. Here, we test the hypothesis that TRIC-A is a physiological component of RyR2-mediated Ca2+ release machinery that directly modulates store overload-induced Ca2+ release activity via CTT. METHODS AND RESULTS We show that cardiomyocytes derived from the TRIC-A-/- (TRIC-A knockout) mice display dysregulated Ca2+ movement across sarcoplasmic reticulum. Biochemical studies demonstrate a direct interaction between CTT-A and RyR2. Modeling and docking studies reveal potential sites on RyR2 that show differential interactions with CTT-A and CTT-B. In HEK293 (human embryonic kidney) cells with stable expression of RyR2, transient expression of TRIC-A, but not TRIC-B, leads to apparent suppression of spontaneous Ca2+ oscillations. Ca2+ measurements using the cytosolic indicator Fura-2 and the endoplasmic reticulum luminal store indicator D1ER suggest that TRIC-A enhances Ca2+ leak across the endoplasmic reticulum by directly targeting RyR2 to modulate store overload-induced Ca2+ release. Moreover, synthetic CTT-A peptide facilitates RyR2 activity in lipid bilayer reconstitution system, enhances Ca2+ sparks in permeabilized TRIC-A-/- cardiomyocytes, and induces intracellular Ca2+ release after microinjection into isolated cardiomyocytes, whereas such effects were not observed with the CTT-B peptide. In response to isoproterenol stimulation, the TRIC-A-/- mice display irregular ECG and develop more fibrosis than the WT (wild type) littermates. CONCLUSIONS In addition to the ion-conducting function, TRIC-A functions as an accessory protein of RyR2 to modulate sarcoplasmic reticulum Ca2+ handling in cardiac muscle.
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Affiliation(s)
- Xinyu Zhou
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Ki Ho Park
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Daiju Yamazaki
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Pei-Hui Lin
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
| | - Miyuki Nishi
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Zhiwei Ma
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Liming Qiu
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan (T.M.)
| | - Xiaoqin Zou
- Department of Physics and Astronomy, Dalton Cardiovascular Research Center (Z.M., L.Q., X. Zou), University of Missouri, Columbia.,Department of Biochemistry (Z.M., L.Q., X. Zou), University of Missouri, Columbia
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Japan (D.Y., M.N., H.T.)
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington (J.Z.)
| | - Jianjie Ma
- From the Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (X. Zhou, K.H.P., P.-h.L., J.M.)
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Kim JC, Pérez-Hernández M, Alvarado FJ, Maurya SR, Montnach J, Yin Y, Zhang M, Lin X, Vasquez C, Heguy A, Liang FX, Woo SH, Morley GE, Rothenberg E, Lundby A, Valdivia HH, Cerrone M, Delmar M. Disruption of Ca 2+i Homeostasis and Connexin 43 Hemichannel Function in the Right Ventricle Precedes Overt Arrhythmogenic Cardiomyopathy in Plakophilin-2-Deficient Mice. Circulation 2019; 140:1015-1030. [PMID: 31315456 DOI: 10.1161/circulationaha.119.039710] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Plakophilin-2 (PKP2) is classically defined as a desmosomal protein. Mutations in PKP2 associate with most cases of gene-positive arrhythmogenic right ventricular cardiomyopathy. A better understanding of PKP2 cardiac biology can help elucidate the mechanisms underlying arrhythmic and cardiomyopathic events consequent to PKP2 deficiency. Here, we sought to capture early molecular/cellular events that can act as nascent arrhythmic/cardiomyopathic substrates. METHODS We used multiple imaging, biochemical and high-resolution mass spectrometry methods to study functional/structural properties of cells/tissues derived from cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout mice (PKP2cKO) 14 days post-tamoxifen injection, a time point preceding overt electrical or structural phenotypes. Myocytes from right or left ventricular free wall were studied separately. RESULTS Most properties of PKP2cKO left ventricular myocytes were not different from control; in contrast, PKP2cKO right ventricular (RV) myocytes showed increased amplitude and duration of Ca2+ transients, increased Ca2+ in the cytoplasm and sarcoplasmic reticulum, increased frequency of spontaneous Ca2+ release events (sparks) even at comparable sarcoplasmic reticulum load, and dynamic Ca2+ accumulation in mitochondria. We also observed early- and delayed-after transients in RV myocytes and heightened susceptibility to arrhythmias in Langendorff-perfused hearts. In addition, ryanodine receptor 2 in PKP2cKO-RV cells presented enhanced Ca2+ sensitivity and preferential phosphorylation in a domain known to modulate Ca2+ gating. RNAseq at 14 days post-tamoxifen showed no relevant difference in transcript abundance between RV and left ventricle, neither in control nor in PKP2cKO cells. Instead, we found an RV-predominant increase in membrane permeability that can permit Ca2+ entry into the cell. Connexin 43 ablation mitigated the membrane permeability increase, accumulation of cytoplasmic Ca2+, increased frequency of sparks and early stages of RV dysfunction. Connexin 43 hemichannel block with GAP19 normalized [Ca2+]i homeostasis. Similarly, protein kinase C inhibition normalized spark frequency at comparable sarcoplasmic reticulum load levels. CONCLUSIONS Loss of PKP2 creates an RV-predominant arrhythmogenic substrate (Ca2+ dysregulation) that precedes the cardiomyopathy; this is, at least in part, mediated by a Connexin 43-dependent membrane conduit and repressed by protein kinase C inhibitors. Given that asymmetric Ca2+ dysregulation precedes the cardiomyopathic stage, we speculate that abnormal Ca2+ handling in RV myocytes can be a trigger for gross structural changes observed at a later stage.
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Affiliation(s)
- Joon-Chul Kim
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Marta Pérez-Hernández
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Francisco J Alvarado
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health (F.J.A., H.H.V.)
| | - Svetlana R Maurya
- Department of Biomedical Sciences (S.R.M., A.L.), Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jerome Montnach
- Institut du Thorax, Nouvelle Universite a Nantes, INSERM, Nantes Cedex 1, France (J.M.)
| | - Yandong Yin
- Department of Pharmacology and Biochemistry (Y.Y., E.R.), New York University School of Medicine
| | - Mingliang Zhang
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Xianming Lin
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Carolina Vasquez
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Adriana Heguy
- Department of Pathology and Genome Technology Center (A.H., G.E.M.), New York University School of Medicine
| | - Feng-Xia Liang
- Microscopy Laboratory, Division of Advanced Research Technologies (F.X.L.), New York University School of Medicine
| | - Sun-Hee Woo
- Laboratory of Physiology, College of Pharmacy, Chungam National University, Daejeon, South Korea (S.H.W.)
| | - Gregory E Morley
- Department of Pathology and Genome Technology Center (A.H., G.E.M.), New York University School of Medicine
| | - Eli Rothenberg
- Department of Pharmacology and Biochemistry (Y.Y., E.R.), New York University School of Medicine
| | - Alicia Lundby
- Department of Biomedical Sciences (S.R.M., A.L.), Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.,NNF Center for Protein Research (A.L.), Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Hector H Valdivia
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health (F.J.A., H.H.V.)
| | - Marina Cerrone
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
| | - Mario Delmar
- The Leon H. Charney Division of Cardiology (J.C.K., M.P.H., M.Z., X.L., C.V., M.C., M.D.), New York University School of Medicine
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Illaste A, Wullschleger M, Fernandez-Tenorio M, Niggli E, Egger M. Automatic Detection and Classification of Ca 2+ Release Events in Line- and Frame-Scan Images. Biophys J 2018; 116:383-394. [PMID: 30638961 DOI: 10.1016/j.bpj.2018.12.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/27/2018] [Accepted: 12/12/2018] [Indexed: 10/27/2022] Open
Abstract
Analysis of Ca2+ signals obtained in various cell types (i.e., cardiomyocytes) is always a tradeoff between acquisition speed and signal/noise ratio of the fluorescence signal. This becomes especially apparent during fast two- or three-dimensional confocal imaging when local intracellular fluorescence signals originating from Ca2+ release from intracellular Ca2+ stores (e.g., sarcoplasmic reticulum) need to be examined. Mathematical methods have been developed to remedy a high noise level by fitting each pixel with a transient function to "denoise" the image. So far, current available analytical approaches have been impaired by a number of constraints (e.g., inability to fit local, concurrent, and consecutive events) and the limited ability to customize implementation. Here, we suggest a, to our knowledge, novel approach for detailed analysis of subcellular micro-Ca2+ events based on pixel-by-pixel denoising of confocal frame- and line-scan images. The algorithm enables spatiotemporally overlapping events (e.g., a Ca2+ spark occurring during the decaying phase of a Ca2+ wave) to be extracted so that various types of Ca2+ events can be detected at a pixel time level of precision. The method allows a nonconstant baseline to be estimated for each pixel, foregoing the need to subtract fluorescence background or apply self-ratio methods before image analysis. Furthermore, by using a clustering algorithm, identified single-pixel events are grouped into "physiologically relevant" Ca2+ signaling events spanning multiple pixels (sparks, waves, puffs, transients, etc.), from which spatiotemporal event parameters (e.g., full duration at half maximal amplitude, full width at half maximal amplitude, amplitude, wave speed, rise, and decay times) can be easily extracted. The method was implemented with cross-platform open source software, providing a comprehensive and easy-to-use graphical user interface enabling rapid line-scan images and rapid frame-scan image sequences (up to 150 frames/s) to be analyzed and repetitive Ca2+ events (Ca2+ sparks and Ca2+ puffs) originating from clusters of Ca2+ release channels located in the sarcoplasmic reticulum membrane (ryanodine receptors and inositol 1,4,5-trisphosphate receptors) of isolated cardiomyocytes to be examined with a high level of precision.
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Affiliation(s)
- Ardo Illaste
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | | | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland.
| | - Marcel Egger
- Department of Physiology, University of Bern, Bern, Switzerland.
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23
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Potenza DM, Janicek R, Fernandez-Tenorio M, Camors E, Ramos-Mondragón R, Valdivia HH, Niggli E. Phosphorylation of the ryanodine receptor 2 at serine 2030 is required for a complete β-adrenergic response. J Gen Physiol 2018; 151:131-145. [PMID: 30541771 PMCID: PMC6363414 DOI: 10.1085/jgp.201812155] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/12/2018] [Accepted: 10/22/2018] [Indexed: 11/20/2022] Open
Abstract
Phosphorylation is thought to play a role in modulation of the ryanodine receptor 2 channel. Using a S2030A knock-in mouse model, Potenza et al. reveal that phosphorylation of RyR2-S2030 mediates channel regulation during the β-adrenergic response. During physical exercise or stress, the sympathetic system stimulates cardiac contractility via β-adrenergic receptor (β-AR) activation, resulting in protein kinase A (PKA)–mediated phosphorylation of the cardiac ryanodine receptor RyR2. PKA-dependent “hyperphosphorylation” of the RyR2 channel has been proposed as a major impairment that contributes to progression of heart failure. However, the sites of PKA phosphorylation and their phosphorylation status in cardiac diseases are not well defined. Among the known RyR2 phosphorylation sites, serine 2030 (S2030) remains highly controversial as a site of functional impact. We examined the contribution of RyR2-S2030 to Ca2+ signaling and excitation–contraction coupling (ECC) in a transgenic mouse with an ablated RyR2-S2030 phosphorylation site (RyR2-S2030A+/+). We assessed ECC gain by using whole-cell patch–clamp recordings and confocal Ca2+ imaging during β-ARs stimulation with isoproterenol (Iso) and consistent SR Ca2+ loading and L-type Ca2+ current (ICa) triggering. Under these conditions, ECC gain is diminished in mutant compared with WT cardiomyocytes. Resting Ca2+ spark frequency (CaSpF) with Iso is also reduced by mutation of S2030. In permeabilized cells, when SR Ca2+ pump activity is kept constant (using 2D12 antibody against phospholamban), cAMP does not change CaSpF in S2030A+/+ myocytes. Using Ca2+ spark recovery analysis, we found that mutant RyR Ca2+ sensitivity is not enhanced by Iso application, contrary to WT RyRs. Furthermore, ablation of RyR2-S2030 prevents acceleration of Ca2+ waves and increases latency to the first spontaneous Ca2+ release after a train of stimulations during Iso treatment. Together, these results suggest that phosphorylation at S2030 may represent an important step in the modulation of RyR2 activity during β-adrenergic stimulation and a potential target for the development of new antiarrhythmic drugs.
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Affiliation(s)
| | | | | | - Emmanuel Camors
- Center for Arrhythmia Research, Department of Medicine, University of Michigan, Ann Arbor, MI
| | - Roberto Ramos-Mondragón
- Center for Arrhythmia Research, Department of Medicine, University of Michigan, Ann Arbor, MI
| | - Héctor H Valdivia
- Department of Medicine, Wisconsin Institutes for Medical Research, University of Wisconsin, Madison, WI.,Center for Arrhythmia Research, Department of Medicine, University of Michigan, Ann Arbor, MI
| | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
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24
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Fernandez-Tenorio M, Niggli E. Stabilization of Ca 2+ signaling in cardiac muscle by stimulation of SERCA. J Mol Cell Cardiol 2018; 119:87-95. [PMID: 29715473 DOI: 10.1016/j.yjmcc.2018.04.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/13/2018] [Accepted: 04/27/2018] [Indexed: 02/06/2023]
Abstract
AIMS In cardiac muscle, phosphorylation of the RyRs is proposed to increase their Ca2+ sensitivity. This mechanism could be arrhythmogenic via facilitation of spontaneous Ca2+ waves. Surprisingly, the level of Ca2+ inside the SR needed to initiate such waves has been reported to increase upon β-adrenergic stimulation, an observation which cannot be easily reconciled with elevated Ca2+ sensitivity of the RyRs. We tested the hypothesis that this change of Ca2+ wave threshold could occur indirectly, subsequent to SERCA stimulation. METHODS AND RESULTS Cytosolic and intra-SR Ca2+ waves were simultaneously recorded with confocal line-scan imaging in intact and permeabilized mouse cardiomyocytes using Rhod-2 and Fluo-5-N, respectively. We analyzed changes of several Ca2+ signaling parameters during specific SERCA stimulation by ochratoxin A (OTA), jasmonate or the Fab fragment of a phospholamban antibody. SERCA stimulation resulted in a substantial increase of the threshold for Ca2+ wave initiation. Faster Ca2+ transient decay and SR refilling confirmed SERCA acceleration. CONCLUSIONS These results suggest that isolated SERCA stimulation can elevate the intra-SR threshold for the generation of Ca2+ waves, independently of RyR phosphorylation. Simultaneously, fractional Ca2+ release and wave amplitudes are reduced. Thus, SERCA stimulation appears to exert a negative feed-back on the Ca2+-induced Ca2+ release mechanisms sustaining the waves. Thereby, it may be profoundly antiarrhythmic. This may be clinically relevant when therapies are applied to stimulate the SERCA activity (e.g. SERCA overexpression with gene therapy, future small molecule SERCA stimulators).
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Affiliation(s)
| | - Ernst Niggli
- Department of Physiology, University of Bern, 3012 Bern, Switzerland.
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25
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Rowlands CT, Owen T, Lawal S, Cao S, Pandey SS, Yang HY, Song W, Wilkinson R, Alvarez-Laviada A, Gehmlich K, Marston SB, MacLeod KT. Age- and strain-related aberrant Ca 2+ release is associated with sudden cardiac death in the ACTC E99K mouse model of hypertrophic cardiomyopathy. Am J Physiol Heart Circ Physiol 2017; 313:H1213-H1226. [PMID: 28887330 DOI: 10.1152/ajpheart.00244.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Patients with hypertrophic cardiomyopathy, particularly young adults, can die from arrhythmia, but the mechanism underlying abnormal rhythm formation remains unknown. C57Bl6 × CBA/Ca mice carrying a cardiac actin ( ACTC) E99K (Glu99Lys) mutation reproduce many aspects of human hypertrophic cardiomyopathy, including increased myofilament Ca2+ sensitivity and sudden death in a proportion (up to 40%) of young (28-40 day old) animals. We studied the hearts of transgenic (TG; ACTC E99K) mice and their non-TG (NTG) littermates when they were in their vulnerable period (28-40 days old) and when they were adult (8-12 wk old). Ventricular myocytes were isolated from the hearts of TG and NTG mice at these two time points. We also examined the hearts of mice that died suddenly (SCD). SCD animals had approximately four times more collagen compared with age-matched NTG mice, yet myocyte cell size was normal. Young TG mice had double the collagen content of NTG mice. Contraction and Ca2+ transients were greater in cells from young TG mice compared with their NTG littermates but not in cells from adult mice (TG or NTG). Cells from young TG mice had a greater propensity for Ca2+ waves than NTG littermates, and, despite similar sarcoplasmic reticulum Ca2+ content, a proportion of these cells had larger Ca2+ spark mass. We found that the probability of SCD in young TG mice was increased when the mutation was expressed in animals with a CBA/Ca2+ background and almost eliminated in mice bred on a C57Bl6 background. The latter TG mice had normal cellular Ca2+ homeostasis. NEW & NOTEWORTHY Mice with the actin Glu99Lys hypertrophic cardiomyopathy mutation ( ACTC E99K) are prone to sudden cardiac death around 40 days, associated with increased Ca2+ transients, spark mass, and fibrosis. However, adult survivors have normal Ca2+ transients and spark density accompanied by hypertrophy. Penetrance of the sudden cardiac death phenotype depends on the genetic background of the mouse. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/calcium-regulation-in-e99k-mouse-heart/ .
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Affiliation(s)
- Christina T Rowlands
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Thomas Owen
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Saheed Lawal
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Shuangyi Cao
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Samata S Pandey
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Hsiang-Yu Yang
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Weihua Song
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Ross Wilkinson
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Anita Alvarez-Laviada
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Katja Gehmlich
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Steven B Marston
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
| | - Kenneth T MacLeod
- National Heart & Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College, Hammersmith Hospital , London , United Kingdom
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26
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Reilly-O'Donnell B, Robertson GB, Karumbi A, McIntyre C, Bal W, Nishi M, Takeshima H, Stewart AJ, Pitt SJ. Dysregulated Zn 2+ homeostasis impairs cardiac type-2 ryanodine receptor and mitsugumin 23 functions, leading to sarcoplasmic reticulum Ca 2+ leakage. J Biol Chem 2017. [PMID: 28630041 PMCID: PMC5555195 DOI: 10.1074/jbc.m117.781708] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Aberrant Zn2+ homeostasis is associated with dysregulated intracellular Ca2+ release, resulting in chronic heart failure. In the failing heart a small population of cardiac ryanodine receptors (RyR2) displays sub-conductance-state gating leading to Ca2+ leakage from sarcoplasmic reticulum (SR) stores, which impairs cardiac contractility. Previous evidence suggests contribution of RyR2-independent Ca2+ leakage through an uncharacterized mechanism. We sought to examine the role of Zn2+ in shaping intracellular Ca2+ release in cardiac muscle. Cardiac SR vesicles prepared from sheep or mouse ventricular tissue were incorporated into phospholipid bilayers under voltage-clamp conditions, and the direct action of Zn2+ on RyR2 channel function was examined. Under diastolic conditions, the addition of pathophysiological concentrations of Zn2+ (≥2 nm) caused dysregulated RyR2-channel openings. Our data also revealed that RyR2 channels are not the only SR Ca2+-permeable channels regulated by Zn2+. Elevating the cytosolic Zn2+ concentration to 1 nm increased the activity of the transmembrane protein mitsugumin 23 (MG23). The current amplitude of the MG23 full-open state was consistent with that previously reported for RyR2 sub-conductance gating, suggesting that in heart failure in which Zn2+ levels are elevated, RyR2 channels do not gate in a sub-conductance state, but rather MG23-gating becomes more apparent. We also show that in H9C2 cells exposed to ischemic conditions, intracellular Zn2+ levels are elevated, coinciding with increased MG23 expression. In conclusion, these data suggest that dysregulated Zn2+ homeostasis alters the function of both RyR2 and MG23 and that both ion channels play a key role in diastolic SR Ca2+ leakage.
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Affiliation(s)
- Benedict Reilly-O'Donnell
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom
| | - Gavin B Robertson
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom
| | - Angela Karumbi
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom
| | - Connor McIntyre
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom
| | - Wojciech Bal
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Science, Warsaw, 02-106 Poland, and
| | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Alan J Stewart
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom
| | - Samantha J Pitt
- From the School of Medicine, University of St. Andrews, St. Andrews, KY16 9TF, Scotland, United Kingdom,
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27
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Srimachai S, Devaux S, Demougeot C, Kumphune S, Ullrich ND, Niggli E, Ingkaninan K, Kamkaew N, Scholfield CN, Tapechum S, Chootip K. Bacopa monnieri extract increases rat coronary flow and protects against myocardial ischemia/reperfusion injury. Altern Ther Health Med 2017; 17:117. [PMID: 28219356 PMCID: PMC5319078 DOI: 10.1186/s12906-017-1637-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/15/2017] [Indexed: 12/11/2022]
Abstract
Background This study explored Bacopa monnieri, a medicinal Ayurvedic herb, as a cardioprotectant against ischemia/reperfusion injury using cardiac function and coronary flow as end-points. Methods In normal isolated rat hearts, coronary flow, left ventricular developed pressure, heart rate, and functional recovery were measured using the Langendorff preparation. Hearts were perfused with either (i) Krebs-Henseleit (normal) solution, (control), or with 30, 100 μg/ml B. monnieri ethanolic extract (30 min), or (ii) with normal solution or extract for 10 min preceding no-perfusion ischemia (30 min) followed by reperfusion (30 min) with normal solution. Infarct volumes were measured by triphenyltetrazolium staining. L-type Ca2+-currents (ICa, L) were measured by whole-cell patching in HL-1 cells, a mouse atrial cardiomyocyte cell line. Cytotoxicity of B. monnieri was assessed in rat isolated ventricular myocytes by trypan blue exclusion. Results In normally perfused hearts, B. monnieri increased coronary flow by 63 ± 13% (30 μg/ml) and 216 ± 21% (100 μg/ml), compared to control (5 ± 3%) (n = 8–10, p < 0.001). B. monnieri treatment preceding ischemia/reperfusion improved left ventricular developed pressure by 84 ± 10% (30 μg/ml), 82 ± 10% (100 μg/ml) and 52 ± 6% (control) compared to pre- ischemia/reperfusion. Similarly, functional recovery showed a sustained increase. Moreover, B. monnieri (100 μg/ml) reduced the percentage of infarct size from 51 ± 2% (control) to 25 ± 2% (n = 6-8, p < 0.0001). B. monnieri (100 μg/ml) reduced ICa, L by 63 ± 4% in HL-1 cells. Ventricular myocyte survival decreased at higher concentrations (50–1000 μg/ml) B. monnieri. Conclusions B. monnieri improves myocardial function following ischemia/reperfusion injury through recovery of coronary blood flow, contractile force and decrease in infarct size. Thus this may lead to a novel cardioprotectant strategy. Electronic supplementary material The online version of this article (doi:10.1186/s12906-017-1637-z) contains supplementary material, which is available to authorized users.
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28
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Alvarado FJ, Chen X, Valdivia HH. Ablation of the cardiac ryanodine receptor phospho-site Ser2808 does not alter the adrenergic response or the progression to heart failure in mice. Elimination of the genetic background as critical variable. J Mol Cell Cardiol 2017; 103:40-47. [PMID: 28065668 DOI: 10.1016/j.yjmcc.2017.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/04/2017] [Indexed: 10/20/2022]
Abstract
BACKGROUND Phosphorylation of the cardiac ryanodine receptor (RyR2) phospho-site S2808 has been touted by the Marks group as a hallmark of heart failure (HF) and a critical mediator of the physiological fight-or-flight response of the heart. In support of this hypothesis, mice unable to undergo phosphorylation at RyR2-S2808 (S2808A) were significantly protected against HF and displayed a blunted response to adrenergic stimulation. However, the issue remains highly controversial because several groups have been unable to reproduce these findings. An important variable not considered before is the genetic background of the mice used to obtain these divergent results. METHODS AND RESULTS We backcrossed a RyR2-S2808A mouse into a congenic C57Bl/6 strain, the same strain used by the Marks group to conduct their experiments. We then performed several key experiments to confirm or discard the genetic background of the mouse as a relevant variable, including induction of HF by myocardial infarction and tests of integrity of adrenergic response. Congenic C57Bl/6 harboring the S2808A mutation showed similar echocardiographic parameters that indicated identical progression towards HF compared to wild type controls, and had a normal response to adrenergic stimulation in whole animal and cellular experiments. CONCLUSIONS The genetic background of the different mouse models is unlikely to be the source of the divergent results obtained by the Marks group in comparison to several other groups. Cardiac adrenergic response and progression towards HF proceed unaltered in mice harboring the RyR2-S2808A mutation. Preventing RyR2-S2808 phosphorylation does not preclude a normal sympathetic response nor mitigates the pathophysiological consequences of MI.
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Affiliation(s)
- Francisco J Alvarado
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States.
| | - Xi Chen
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Héctor H Valdivia
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, United States; Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States.
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29
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Ho HT, Belevych AE, Liu B, Bonilla IM, Radwański PB, Kubasov IV, Valdivia HH, Schober K, Carnes CA, Györke S. Muscarinic Stimulation Facilitates Sarcoplasmic Reticulum Ca Release by Modulating Ryanodine Receptor 2 Phosphorylation Through Protein Kinase G and Ca/Calmodulin-Dependent Protein Kinase II. Hypertension 2016; 68:1171-1178. [PMID: 27647848 DOI: 10.1161/hypertensionaha.116.07666] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 08/21/2016] [Indexed: 01/01/2023]
Abstract
Although the effects and the underlying mechanism of sympathetic stimulation on cardiac Ca handling are relatively well established both in health and disease, the modes of action and mechanisms of parasympathetic modulation are poorly defined. Here, we demonstrate that parasympathetic stimulation initiates a novel mode of excitation-contraction coupling that enhances the efficiency of cardiac sarcoplasmic reticulum Ca store utilization. This efficient mode of excitation-contraction coupling involves reciprocal changes in the phosphorylation of ryanodine receptor 2 at Ser-2808 and Ser-2814. Specifically, Ser-2808 phosphorylation was mediated by muscarinic receptor subtype 2 and activation of PKG (protein kinase G), whereas dephosphorylation of Ser-2814 involved activation of muscarinic receptor subtype 3 and decreased reactive oxygen species-dependent activation of CaMKII (Ca/calmodulin-dependent protein kinase II). The overall effect of these changes in phosphorylation of ryanodine receptor 2 is an increase in systolic Ca release at the low sarcoplasmic reticulum Ca content and a paradoxical reduction in aberrant Ca leak. Accordingly, cholinergic stimulation of cardiomyocytes isolated from failing hearts improved Ca cycling efficiency by restoring altered ryanodine receptor 2 phosphorylation balance.
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Affiliation(s)
- Hsiang-Ting Ho
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Andriy E Belevych
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Bin Liu
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Ingrid M Bonilla
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Przemysław B Radwański
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Igor V Kubasov
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Héctor H Valdivia
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Karsten Schober
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Cynthia A Carnes
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.)
| | - Sándor Györke
- From the Department of Physiology and Cell Biology (H.-T.H., A.E.B., B.L., P.B.R., S.G.), College of Pharmacy (I.M.B., P.B.R., C.A.C.), and College of Veterinary Medicine (K.S.), The Ohio State University, Columbus; Davis Heart and Lung Research Institute, Columbus, OH (H.-T.H., A.E.B., B.L., I.M.B., P.B.R., C.A.C., S.G.); Department of Medicine, Duke University, Durham, NC (H.-T.H.); Laboratory of Neuromuscular Physiology, I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Petersburg, Russia (I.V.K.); and Center for Arrhythmia Research, Cardiovascular Division of the Department of Internal Medicine, University of Michigan, Ann Arbor (H.H.V.).
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Terentyev D, Hamilton S. Regulation of sarcoplasmic reticulum Ca 2+ release by serine-threonine phosphatases in the heart. J Mol Cell Cardiol 2016; 101:156-164. [PMID: 27585747 DOI: 10.1016/j.yjmcc.2016.08.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 08/26/2016] [Accepted: 08/27/2016] [Indexed: 12/17/2022]
Abstract
The amount and timing of Ca2+ release from the sarcoplasmic reticulum (SR) during cardiac cycle are the main determinants of cardiac contractility. Reversible phosphorylation of the SR Ca2+ release channel, ryanodine receptor type 2 (RyR2) is the central mechanism of regulation of Ca2+ release in cardiomyocytes. Three major serine-threonine phosphatases including PP1, PP2A and PP2B (calcineurin) have been implicated in modulation of RyR2 function. Changes in expression levels of these phosphatases, their activity and targeting to the RyR2 macromolecular complex were demonstrated in many animal models of cardiac disease and humans and are implicated in cardiac arrhythmia and heart failure. Here we review evidence in support of regulation of RyR2-mediated SR Ca2+ release by serine-threonine phosphatases and the role and mechanisms of dysregulation of phosphatases in various disease states.
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Affiliation(s)
- Dmitry Terentyev
- The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Department of Medicine, Cardiovascular Research Center, United States.
| | - Shanna Hamilton
- Cardiff University, School of Medicine, Wales Heart Research Institute, United Kingdom
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The ryanodine receptor provides high throughput Ca2+-release but is precisely regulated by networks of associated proteins: a focus on proteins relevant to phosphorylation. Biochem Soc Trans 2016; 43:426-33. [PMID: 26009186 DOI: 10.1042/bst20140297] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Once opened, ryanodine receptors (RyR) are efficient pathways for the release of Ca2+ from the endoplasmic/sarcoplasmic reticulum (ER/SR). The precise nature of the Ca2+-release event, however, requires fine-tuning for the specific process and type of cell involved. For example, the spatial organization of RyRs, the luminal [Ca2+] and the influence of soluble regulators that fluctuate under physiological and pathophysiological control mechanisms, all affect the amplitude and duration of RyR Ca2+ fluxes. Various proteins are docked tightly to the huge bulky structure of RyR and there is growing evidence that, together, they provide a sophisticated and integrated system for regulating RyR channel gating. This review focuses on those proteins that are relevant to phosphorylation of RyR channels with particular reference to the cardiac isoform of RyR (RyR2). How phosphorylation of RyR affects channel activity and whether proteins such as the FK-506 binding proteins (FKBP12 and FKBP12.6) are involved, have been highly controversial subjects for more than a decade. But that is expected given the large number of participating proteins, the relevance of phosphorylation in heart failure and inherited arrhythmic diseases, and the frustrations of predicting relationships between structure and function before the advent of a high resolution structure of RyR.
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Chen S, Wang Z, Xu B, Mi X, Sun W, Quan N, Wang L, Chen X, Liu Q, Zheng Y, Leng J, Li J. The Modulation of Cardiac Contractile Function by the Pharmacological and Toxicological Effects of Urocortin2. Toxicol Sci 2015; 148:581-93. [PMID: 26342213 PMCID: PMC5009442 DOI: 10.1093/toxsci/kfv202] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Urocortin2 (Ucn2) has been revealed to enhance cardiac function in heart failure. However, the pharmacological and toxicological effects of Ucn2 on cardiomyocytes are incompletely understood. In this study, we investigated the possible mechanisms of Ucn2 on mediating the contractility of cardiomyocytes. Mechanical properties and intracellular Ca(2+) properties were measured in isolated cardiomyocytes from different treatment groups. The stress signaling was evaluated using Western blot. The results demonstrated that Ucn2 induced maximal velocity of shortening (+dL/dt), peak height, peak shortening (PS) amplitude, maximal velocity of relengthening (-dL/dt), accompanied by a significant rise in intracellular Ca(2+) level and a fall of the mean time constant of Ca(2+) transient decay (Tau) in WT cardiomyocytes. However, these effects were abolished by preincubation of type 2 CRF receptors (CRFR2) antagonist anti-sauvagine 30 (a-SVG-30). We also found that Ucn2 treatment activated the AMPK pathway in isolated cardiomyocytes via CRFR2. Furthermore, Ucn2 induced protein kinase A (PKA) and phospholamban (PLN) phosphorylation. Pretreatment of PKA inhibitor H89 reduced the inotropic and lusitropic effects of Ucn2 as well as decreased the intracellular Ca(2+) load and slowed down the Ca(2+) transient decay. We also showed that preincubation of Compound C, an inhibitor of AMPK, inhibited the phosphorylation of PKA and the intracellular Ca(2+) level in cardiomyocytes without affecting the contractile function and the Tau of cardiomyocytes. Taken together, it suggests that Ucn2 facilitate the contractility of cardiomyocytes via activating both AMPK and PKA.
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Affiliation(s)
- Si Chen
- State University of New York at Buffalo, Buffalo, New York 14214
| | - Zhenhua Wang
- *College of Life Sciences, Yantai University, Yantai, Shandong 264005
| | - Bo Xu
- *College of Life Sciences, Yantai University, Yantai, Shandong 264005, Key Laboratory of Pharmacology and Molecular Drug Evaluation, School of Pharmacy, Yantai University, Yantai, Shandong 264005
| | - Xiangquan Mi
- School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000
| | - Wanqing Sun
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216, and The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Nanhu Quan
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216, and The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Lin Wang
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216, and The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Xingchi Chen
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216, and
| | - Quan Liu
- The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Yang Zheng
- The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Jiyan Leng
- The First Affiliated Hospital, Jilin University, Changchun, Jilin 130000
| | - Ji Li
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi 39216, and
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Sá FGDSD, Lima-Leopoldo AP, Jacobsen BB, Ferron AJT, Estevam WM, Campos DHS, Castardeli E, Cunha MRHD, Cicogna AC, Leopoldo AS. Obesity Resistance Promotes Mild Contractile Dysfunction Associated with Intracellular Ca2+ Handling. Arq Bras Cardiol 2015; 105:588-96. [PMID: 26761369 PMCID: PMC4693663 DOI: 10.5935/abc.20150134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 07/28/2015] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Diet-induced obesity is frequently used to demonstrate cardiac dysfunction. However, some rats, like humans, are susceptible to developing an obesity phenotype, whereas others are resistant to that. OBJECTIVE To evaluate the association between obesity resistance and cardiac function, and the impact of obesity resistance on calcium handling. METHODS Thirty-day-old male Wistar rats were distributed into two groups, each with 54 animals: control (C; standard diet) and obese (four palatable high-fat diets) for 15 weeks. After the experimental protocol, rats consuming the high-fat diets were classified according to the adiposity index and subdivided into obesity-prone (OP) and obesity-resistant (OR). Nutritional profile, comorbidities, and cardiac remodeling were evaluated. Cardiac function was assessed by papillary muscle evaluation at baseline and after inotropic maneuvers. RESULTS The high-fat diets promoted increase in body fat and adiposity index in OP rats compared with C and OR rats. Glucose, lipid, and blood pressure profiles remained unchanged in OR rats. In addition, the total heart weight and the weight of the left and right ventricles in OR rats were lower than those in OP rats, but similar to those in C rats. Baseline cardiac muscle data were similar in all rats, but myocardial responsiveness to a post-rest contraction stimulus was compromised in OP and OR rats compared with C rats. CONCLUSION Obesity resistance promoted specific changes in the contraction phase without changes in the relaxation phase. This mild abnormality may be related to intracellular Ca2+ handling.
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Affiliation(s)
| | - Ana Paula Lima-Leopoldo
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Bruno Barcellos Jacobsen
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Artur Junio Togneri Ferron
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Wagner Muller Estevam
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Dijon Henrique Salomé Campos
- Departamento de Clínica Médica, Faculdade de Medicina, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Edson Castardeli
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Márcia Regina Holanda da Cunha
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Antonio Carlos Cicogna
- Departamento de Clínica Médica, Faculdade de Medicina, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - André Soares Leopoldo
- Departamento de Desportos, Centro de Educação Física e Desportos, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
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34
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Marcu IC, Illaste A, Heuking P, Jaconi ME, Ullrich ND. Functional Characterization and Comparison of Intercellular Communication in Stem Cell-Derived Cardiomyocytes. Stem Cells 2015; 33:2208-18. [PMID: 25968594 DOI: 10.1002/stem.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/08/2015] [Indexed: 02/05/2023]
Abstract
One novel treatment strategy for the diseased heart focuses on the use of pluripotent stem cell-derived cardiomyocytes (SC-CMs) to overcome the heart's innate deficiency for self-repair. However, targeted application of SC-CMs requires in-depth characterization of their true cardiogenic potential in terms of excitability and intercellular coupling at cellular level and in multicellular preparations. In this study, we elucidated the electrical characteristics of single SC-CMs and intercellular coupling quality of cell pairs, and concomitantly compared them with well-characterized murine native neonatal and immortalized HL-1 cardiomyocytes. Firstly, we investigated the electrical properties and Ca(2+) signaling mechanisms specific to cardiac contraction in single SC-CMs. Despite heterogeneity of the new cardiac cell population, their electrophysiological activity and Ca(2+) handling were similar to native cells. Secondly, we investigated the capability of paired SC-CMs to form an adequate subunit of a functional syncytium and analyzed gap junctions and signal transmission by dye transfer in cell pairs. We discovered significantly diminished coupling in SC-CMs compared with native cells, which could not be enhanced by a coculture approach combining SC-CMs and primary CMs. Moreover, quantitative and structural analysis of gap junctions presented significantly reduced connexin expression levels compared with native CMs. Strong dependence of intercellular coupling on gap junction density was further confirmed by computational simulations. These novel findings demonstrate that despite the cardiogenic electrophysiological profile, SC-CMs present significant limitations in intercellular communication. Inadequate coupling may severely impair functional integration and signal transmission, which needs to be carefully considered for the prospective use of SC-CMs in cardiac repair. Stem Cells 2015;33:2208-2218.
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Affiliation(s)
- Irene C Marcu
- Department of Physiology, University of Bern, Bern, Switzerland.,Department of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Ardo Illaste
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Pernilla Heuking
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Marisa E Jaconi
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Nina D Ullrich
- Department of Physiology, University of Bern, Bern, Switzerland.,Department of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
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Ferreira R, Moreira-Gonçalves D, Azevedo AL, Duarte JA, Amado F, Vitorino R. Unraveling the exercise-related proteome signature in heart. Basic Res Cardiol 2014; 110:454. [PMID: 25475830 DOI: 10.1007/s00395-014-0454-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/30/2014] [Accepted: 11/19/2014] [Indexed: 12/15/2022]
Abstract
Exercise training is a well-known non-pharmacological strategy for the prevention and treatment of cardiovascular diseases. Despite the established phenotypic knowledge, the molecular signature of exercise-induced cardiac remodeling remains poorly characterized. The great majority of studies dedicated to this topic use conventional reductionist methods, which only allow analyzing individual protein candidates. Nowadays, several methodologies based on mass spectrometry are available and have been successfully applied for the characterization of heart proteome, representing an attractive approach for the wide characterization of the complex molecular networks that underlie exercise-induced cardiac remodeling. Still, few studies have used these methodologies to understand the impact of exercise training on the remodeling of cardiac proteome. The present study analyzes the few available data obtained from mass spectrometry (MS)-based proteomic studies assessing the impact of distinct types of exercise training on the protein profile of heart (left ventricle and isolated mitochondria) and the potential cross-tolerance between exercise training and diseases as myocardial infarction and obesity. Network analysis was performed with bioinformatics to integrate data from distinct research papers, based on distinct exercise training protocols, animal models and methodological approaches applied in the characterization of heart proteome. The analysis revealed that exercise training confers a unique proteome signature characterized by the up-regulation of lipid and organic metabolic processes, vasculogenesis and tissue regeneration. Data retrieved from this analysis also suggested that cardiac mitochondrial proteome is highly dynamic in response to exercise training due, in part, to the action of specific kinases as PKA and PKG. Regarding to the type of exercise, treadmill training seems to have a greater effect on the modulation of cardiac proteome than swimming. Data from the present review will certainly open new perspectives on cardiac proteomics and will help to envisage future studies targeting the identification of the regulatory mechanisms underlying cardiac adaptive and maladaptive remodeling.
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Affiliation(s)
- Rita Ferreira
- Mass Spectrometry Group, QOPNA, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal,
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Yang X, Wang T, Lin X, Yue X, Wang Q, Wang G, Fu Q, Ai X, Chiang DY, Miyake CY, Wehrens XHT, Chang J. Genetic deletion of Rnd3/RhoE results in mouse heart calcium leakage through upregulation of protein kinase A signaling. Circ Res 2014; 116:e1-e10. [PMID: 25348166 DOI: 10.1161/circresaha.116.304940] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
RATIONALE Rnd3, a small Rho GTPase, is involved in the regulation of cell actin cytoskeleton dynamics, cell migration, and proliferation. The biological function of Rnd3 in the heart remains unexplored. OBJECTIVE To define the functional role of the Rnd3 gene in the animal heart and investigate the associated molecular mechanism. METHODS AND RESULTS By loss-of-function approaches, we discovered that Rnd3 is involved in calcium regulation in cardiomyocytes. Rnd3-null mice died at the embryonic stage with fetal arrhythmias. The deletion of Rnd3 resulted in severe Ca(2+) leakage through destabilized ryanodine receptor type 2 Ca(2+) release channels. We further found that downregulation of Rnd3 attenuated β2-adrenergic receptor lysosomal targeting and ubiquitination, which in turn resulted in the elevation of β2-adrenergic receptor protein levels leading to the hyperactivation of protein kinase A (PKA) signaling. The PKA activation destabilized ryanodine receptor type 2 channels. This irregular spontaneous Ca(2+) release can be curtailed by PKA inhibitor treatment. Increases in the PKA activity along with elevated cAMP levels were detected in Rnd3-null embryos, in neonatal rat cardiomyocytes, and noncardiac cell lines with Rnd3 knockdown, suggesting a general mechanism for Rnd3-mediated PKA signaling activation. β2-Adrenergic receptor blocker treatment reduced arrhythmia and improved cardiac function. CONCLUSIONS Rnd3 is a novel factor involved in intracellular Ca(2+) homeostasis regulation in the heart. Deficiency of the protein induces ryanodine receptor type 2 dysfunction by a mechanism that attenuates Rnd3-mediated β2-adrenergic receptor ubiquitination, which leads to the activation of PKA signaling. Increased PKA signaling in turn promotes ryanodine receptor type 2 hyperphosphorylation, which contributes to arrhythmogenesis and heart failure.
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Affiliation(s)
- Xiangsheng Yang
- Texas A&M University Health Science Center, Institute of Biosciences and Technology, Houston, TX 77030
| | - Tiannan Wang
- Department of Molecular Physiology & Biophysics, and Medicine (Cardiology), Baylor College of Medicine, Houston, TX 77030
| | - Xi Lin
- Texas A&M University Health Science Center, Institute of Biosciences and Technology, Houston, TX 77030
| | - Xiaojing Yue
- Texas A&M University Health Science Center, Institute of Biosciences and Technology, Houston, TX 77030
| | - Qiongling Wang
- Department of Molecular Physiology & Biophysics, and Medicine (Cardiology), Baylor College of Medicine, Houston, TX 77030
| | - Guoliang Wang
- Department of Molecular Physiology & Biophysics, and Medicine (Cardiology), Baylor College of Medicine, Houston, TX 77030
| | - Qin Fu
- Department of Pharmacology, University of California at Davis, CA 95616
| | - Xun Ai
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153
| | - David Y Chiang
- Department of Molecular Physiology & Biophysics, and Medicine (Cardiology), Baylor College of Medicine, Houston, TX 77030
| | - Christina Y Miyake
- Texas Children's Hospital, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Xander H T Wehrens
- Department of Molecular Physiology & Biophysics, and Medicine (Cardiology), Baylor College of Medicine, Houston, TX 77030
| | - Jiang Chang
- Texas A&M University Health Science Center, Institute of Biosciences and Technology, Houston, TX 77030
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Gonano LA, Morell M, Burgos JI, Dulce RA, De Giusti VC, Aiello EA, Hare JM, Vila Petroff M. Hypotonic swelling promotes nitric oxide release in cardiac ventricular myocytes: impact on swelling-induced negative inotropic effect. Cardiovasc Res 2014; 104:456-66. [PMID: 25344365 DOI: 10.1093/cvr/cvu230] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Cardiomyocyte swelling occurs in multiple pathological situations and has been associated with contractile dysfunction, cell death, and enhanced propensity to arrhythmias. We investigate whether hypotonic swelling promotes nitric oxide (NO) release in cardiomyocytes, and whether it impacts on swelling-induced contractile dysfunction. METHODS AND RESULTS Superfusing rat cardiomyocytes with a hypotonic solution (HS; 217 mOsm), increased cell volume, reduced myocyte contraction and Ca(2+) transient, and increased NO-sensitive 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) fluorescence. When cells were exposed to HS + 2.5 mM of the NO synthase inhibitor l-NAME, cell swelling occurred in the absence of NO release. Swelling-induced NO release was also prevented by the nitric oxide synthase 1 (NOS1) inhibitor, nitroguanidine, and significantly reduced in NOS1 knockout mice. Additionally, colchicine (inhibitor of microtubule polymerization) prevented the increase in DAF-FM fluorescence induced by HS, indicating that microtubule integrity is necessary for swelling-induced NO release. The swelling-induced negative inotropic effect was exacerbated in the presence of either l-NAME, nitroguandine, the guanylate cyclase inhibitor, ODQ, or the PKG inhibitor, KT5823, suggesting that NOS1-derived NO provides contractile support via a cGMP/PKG-dependent mechanism. Indeed, ODQ reduced Ca(2+) wave velocity and both ODQ and KT5823 reduced the HS-induced increment in ryanodine receptor (RyR2, Ser2808) phosphorylation, suggesting that in this context, cGMP/PKG may contribute to preserve contractile function by enhancing sarcoplasmic reticulum Ca(2+) release. CONCLUSIONS Our findings suggest a novel mechanism for NO release in cardiomyocytes with putative pathophysiological relevance determined, at least in part, by its capability to reduce the extent of contractile dysfunction associated with hypotonic swelling.
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Affiliation(s)
- Luis Alberto Gonano
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
| | - Malena Morell
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
| | - Juan Ignacio Burgos
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
| | - Raul Ariel Dulce
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Verónica Celeste De Giusti
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
| | - Ernesto Alejandro Aiello
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
| | - Joshua Michael Hare
- Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Martin Vila Petroff
- Centro de Investigaciones Cardiovasculares, CONICET La Plata, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, La Plata 1900, Argentina
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Poláková E, Illaste A, Niggli E, Sobie EA. Maximal acceleration of Ca2+ release refractoriness by β-adrenergic stimulation requires dual activation of kinases PKA and CaMKII in mouse ventricular myocytes. J Physiol 2014; 593:1495-507. [PMID: 25772298 DOI: 10.1113/jphysiol.2014.278051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 08/30/2014] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Refractoriness of calcium release in heart cells is altered in several disease states, but the physiological mechanisms that regulate this process are incompletely understood. We examined refractoriness of calcium release in mouse ventricular myocytes and investigated how activation of different intracellular signalling pathways influenced this process. We found that refractoriness of calcium release is abbreviated by stimulation of the 'fight-or-flight' response, and that simultaneous activation of multiple intracellular signalling pathways contributes to this response. Data obtained under several conditions at the subcellular, microscopic level were consistent with results obtained at the cellular level. The results provide insight into regulation of cardiac calcium release and how alterations to this process may increase arrhythmia risk under different conditions. ABSTRACT Time-dependent refractoriness of calcium (Ca(2+)) release in cardiac myocytes is an important factor in determining whether pro-arrhythmic release patterns develop. At the subcellular level of the Ca(2+) spark, recent studies have suggested that recovery of spark amplitude is controlled by local sarcoplasmic reticulum (SR) refilling whereas refractoriness of spark triggering depends on both refilling and the sensitivity of the ryanodine receptor (RyR) release channels that produce sparks. Here we studied regulation of Ca(2+) spark refractoriness in mouse ventricular myocytes by examining how β-adrenergic stimulation influenced sequences of Ca(2+) sparks originating from individual RyR clusters. Our protocol allowed us to separately measure recovery of spark amplitude and delays between successive sparks, and data were interpreted quantitatively through simulations with a stochastic mathematical model. We found that, compared with spark sequences measured under control conditions: (1) β-adrenergic stimulation with isoproterenol (isoprenaline) accelerated spark amplitude recovery and decreased spark-to-spark delays; (2) activating protein kinase A (PKA) with forskolin accelerated amplitude recovery but did not affect spark-to-spark delays; (3) inhibiting PKA with H89 retarded amplitude recovery and increased spark-to-spark delays; (4) preventing phosphorylation of the RyR at serine 2808 with a knock-in mouse prevented the decrease in spark-to-spark delays seen with β-adrenergic stimulation; (5) inhibiting either PKA or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) during β-adrenergic stimulation prevented the decrease in spark-to-spark delays seen without inhibition. The results suggest that activation of either PKA or CaMKII is sufficient to speed SR refilling, but activation of both kinases appears necessary to observe increased RyR sensitivity. The data provide novel insight into β-adrenergic regulation of Ca(2+) release refractoriness in mouse myocytes.
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Affiliation(s)
- Eva Poláková
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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39
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Dobrev D, Wehrens XHT. Role of RyR2 phosphorylation in heart failure and arrhythmias: Controversies around ryanodine receptor phosphorylation in cardiac disease. Circ Res 2014; 114:1311-9; discussion 1319. [PMID: 24723656 DOI: 10.1161/circresaha.114.300568] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiac ryanodine receptor type 2 plays a key role in excitation-contraction coupling. The ryanodine receptor type 2 channel protein is modulated by various post-translational modifications, including phosphorylation by protein kinase A and Ca(2+)/calmodulin protein kinase II. Despite extensive research in this area, the functional effects of ryanodine receptor type 2 phosphorylation remain disputed. In particular, the potential involvement of increased ryanodine receptor type 2 phosphorylation in the pathogenesis of heart failure and arrhythmias remains a controversial area, which is discussed in this review article.
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Affiliation(s)
- Dobromir Dobrev
- From the Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (D.D.); and Cardiovascular Research Institute, Departments of Molecular Physiology and Biophysics, and Medicine-Cardiology, Baylor College of Medicine, Houston, TX (X.H.T.W.)
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Rueda A, de Alba-Aguayo DR, Valdivia HH. [Ryanodine receptor, calcium leak and arrhythmias]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2014; 84:191-201. [PMID: 25103920 DOI: 10.1016/j.acmx.2013.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/30/2013] [Accepted: 12/02/2013] [Indexed: 11/28/2022] Open
Abstract
The participation of the ionic Ca(2+) release channel/ryanodine receptor in cardiac excitation-contraction coupling is well known since the late '80s, when various seminal papers communicated its purification for the first time and its identity with the "foot" structures located at the terminal cisternae of the sarcoplasmic reticulum. In addition to its main role as the Ca(2+) channel responsible for the transient Ca(2+) increase that activates the contractile machinery of the cardiomyocytes, the ryanodine receptor releases Ca(2+) during the relaxation phase of the cardiac cycle, giving rise to a diastolic Ca(2+) leak. In normal physiological conditions, diastolic Ca(2+) leak regulates the proper level of luminal Ca(2+), but in pathological conditions it participates in the generation of both, acquired and hereditary arrhythmias. Very recently, several groups have focused their efforts into the development of pharmacological tools to control the altered diastolic Ca(2+) leak via ryanodine receptors. In this review, we focus our interest on describing the participation of cardiac ryanodine receptor in the diastolic Ca(2+) leak under physiological or pathological conditions and also on the therapeutic approaches to control its undesired exacerbated activity during diastole.
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Affiliation(s)
- Angélica Rueda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Zacatenco, México D.F., México.
| | - David R de Alba-Aguayo
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Zacatenco, México D.F., México
| | - Héctor H Valdivia
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, Estados Unidos
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Zucchetti AE, Barosso IR, Boaglio AC, Basiglio CL, Miszczuk G, Larocca MC, Ruiz ML, Davio CA, Roma MG, Crocenzi FA, Pozzi EJS. G-protein-coupled receptor 30/adenylyl cyclase/protein kinase A pathway is involved in estradiol 17ß-D-glucuronide-induced cholestasis. Hepatology 2014; 59:1016-29. [PMID: 24115158 DOI: 10.1002/hep.26752] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 09/16/2013] [Indexed: 12/16/2022]
Abstract
UNLABELLED Estradiol-17ß-D-glucuronide (E17G) activates different signaling pathways (e.g., Ca(2+) -dependent protein kinase C, phosphoinositide 3-kinase/protein kinase B, mitogen-activated protein kinases [MAPKs] p38 and extracellular signal-related kinase 1/2, and estrogen receptor alpha) that lead to acute cholestasis in rat liver with retrieval of the canalicular transporters, bile salt export pump (Abcb11) and multidrug resistance-associated protein 2 (Abcc2). E17G shares with nonconjugated estradiol the capacity to activate these pathways. G-protein-coupled receptor 30 (GPR30) is a receptor implicated in nongenomic effects of estradiol, and the aim of this study was to analyze the potential role of this receptor and its downstream effectors in E17G-induced cholestasis. In vitro, GPR30 inhibition by G15 or its knockdown with small interfering RNA strongly prevented E17G-induced impairment of canalicular transporter function and localization. E17G increased cyclic adenosine monophosphate (cAMP) levels, and this increase was blocked by G15, linking GPR30 to adenylyl cyclase (AC). Moreover, AC inhibition totally prevented E17G insult. E17G also increased protein kinase A (PKA) activity, which was blocked by G15 and AC inhibitors, connecting the links of the pathway, GPR30-AC-PKA. PKA inhibition prevented E17G-induced cholestasis, whereas exchange protein activated directly by cyclic nucleotide/MAPK kinase, another cAMP downstream effector, was not implicated in cAMP cholestatic action. In the perfused rat liver model, inhibition of the GPR30-AC-PKA pathway totally prevented E17G-induced alteration in Abcb11 and Abcc2 function and localization. CONCLUSION Activation of GPR30-AC-PKA is a key factor in the alteration of canalicular transporter function and localization induced by E17G. Interaction of E17G with GPR30 may be the first event in the cascade of signaling activation.
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Affiliation(s)
- Andrés E Zucchetti
- Instituto de Fisiología Experimental (IFISE), Facultad de Ciencias Bioquímicas y Farmacéuticas (CONICET-U.N.R.), Rosario, Argentina
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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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Sirenko S, Maltsev VA, Maltseva LA, Yang D, Lukyanenko Y, Vinogradova TM, Jones LR, Lakatta EG. Sarcoplasmic reticulum Ca2+ cycling protein phosphorylation in a physiologic Ca2+ milieu unleashes a high-power, rhythmic Ca2+ clock in ventricular myocytes: relevance to arrhythmias and bio-pacemaker design. J Mol Cell Cardiol 2014; 66:106-15. [PMID: 24274954 PMCID: PMC3896924 DOI: 10.1016/j.yjmcc.2013.11.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 11/07/2013] [Accepted: 11/14/2013] [Indexed: 10/26/2022]
Abstract
Basal phosphorylation of sarcoplasmic reticulum (SR) Ca(2+) proteins is high in sinoatrial nodal cells (SANC), which generate partially synchronized, spontaneous, rhythmic, diastolic local Ca(2+) releases (LCRs), but low in ventricular myocytes (VM), which exhibit rare diastolic, stochastic SR-generated Ca(2+) sparks. We tested the hypothesis that in a physiologic Ca(2+) milieu, and independent of increased Ca(2+) influx, an increase in basal phosphorylation of SR Ca(2+) cycling proteins will convert stochastic Ca(2+) sparks into periodic, high-power Ca(2+) signals of the type that drives SANC normal automaticity. We measured phosphorylation of SR-associated proteins, phospholamban (PLB) and ryanodine receptors (RyR), and spontaneous local Ca(2+) release characteristics (LCR) in permeabilized single, rabbit VM in physiologic [Ca(2+)], prior to and during inhibition of protein phosphatase (PP) and phosphodiesterase (PDE), or addition of exogenous cAMP, or in the presence of an antibody (2D12), that specifically inhibits binding of the PLB to SERCA-2. In the absence of the aforementioned perturbations, VM could only generate stochastic local Ca(2+) releases of low power and low amplitude, as assessed by confocal Ca(2+) imaging and spectral analysis. When the kinetics of Ca(2+) pumping into the SR were increased by an increase in PLB phosphorylation (via PDE and PP inhibition or addition of cAMP) or by 2D12, self-organized, "clock-like" local Ca(2+) releases, partially synchronized in space and time (Ca(2+) wavelets), emerged, and the ensemble of these rhythmic local Ca(2+) wavelets generated a periodic high-amplitude Ca(2+) signal. Thus, a Ca(2+) clock is not specific to pacemaker cells, but can also be unleashed in VM when SR Ca(2+) cycling increases and spontaneous local Ca(2+) release becomes partially synchronized. This unleashed Ca(2+) clock that emerges in a physiological Ca(2+) milieu in VM has two faces, however: it can provoke ventricular arrhythmias; or if harnessed, can be an important feature of novel bio-pacemaker designs.
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Affiliation(s)
- Syevda Sirenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Larissa A Maltseva
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Yevgeniya Lukyanenko
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Larry R Jones
- Department of Medicine, Krannert Institute of Cardiology, Indianapolis, IN, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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Multiple actions of phi-LITX-Lw1a on ryanodine receptors reveal a functional link between scorpion DDH and ICK toxins. Proc Natl Acad Sci U S A 2013; 110:8906-11. [PMID: 23671114 DOI: 10.1073/pnas.1214062110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We recently reported the isolation of a scorpion toxin named U1-liotoxin-Lw1a (U1-LITX-Lw1a) that adopts an unusual 3D fold termed the disulfide-directed hairpin (DDH) motif, which is the proposed evolutionary structural precursor of the three-disulfide-containing inhibitor cystine knot (ICK) motif found widely in animals and plants. Here we reveal that U1-LITX-Lw1a targets and activates the mammalian ryanodine receptor intracellular calcium release channel (RyR) with high (fM) potency and provides a functional link between DDH and ICK scorpion toxins. Moreover, U1-LITX-Lw1a, now described as ϕ-liotoxin-Lw1a (ϕ-LITX-Lw1a), has a similar mode of action on RyRs as scorpion calcines, although with significantly greater potency, inducing full channel openings at lower (fM) toxin concentrations whereas at higher pM concentrations increasing the frequency and duration of channel openings to a submaximal state. In addition, we show that the C-terminal residue of ϕ-LITX-Lw1a is crucial for the increase in full receptor openings but not for the increase in receptor subconductance opening, thereby supporting the two-binding-site hypothesis of scorpion toxins on RyRs. ϕ-LITX-Lw1a has potential both as a pharmacological tool and as a lead molecule for the treatment of human diseases that involve RyRs, such as malignant hyperthermia and polymorphic ventricular tachycardia.
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Li J, Imtiaz MS, Beard NA, Dulhunty AF, Thorne R, vanHelden DF, Laver DR. ß-Adrenergic stimulation increases RyR2 activity via intracellular Ca2+ and Mg2+ regulation. PLoS One 2013; 8:e58334. [PMID: 23533585 PMCID: PMC3606165 DOI: 10.1371/journal.pone.0058334] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/02/2013] [Indexed: 01/19/2023] Open
Abstract
Here we investigate how ß-adrenergic stimulation of the heart alters regulation of ryanodine receptors (RyRs) by intracellular Ca2+ and Mg2+ and the role of these changes in SR Ca2+ release. RyRs were isolated from rat hearts, perfused in a Langendorff apparatus for 5 min and subject to 1 min perfusion with 1 µM isoproterenol or without (control) and snap frozen in liquid N2 to capture their phosphorylation state. Western Blots show that RyR2 phosphorylation was increased by isoproterenol, confirming that RyR2 were subject to normal ß-adrenergic signaling. Under basal conditions, S2808 and S2814 had phosphorylation levels of 69% and 15%, respectively. These levels were increased to 83% and 60%, respectively, after 60 s of ß-adrenergic stimulation consistent with other reports that ß-adrenergic stimulation of the heart can phosphorylate RyRs at specific residues including S2808 and S2814 causing an increase in RyR activity. At cytoplasmic [Ca2+] <1 µM, ß-adrenergic stimulation increased luminal Ca2+ activation of single RyR channels, decreased luminal Mg2+ inhibition and decreased inhibition of RyRs by mM cytoplasmic Mg2+. At cytoplasmic [Ca2+] >1 µM, ß-adrenergic stimulation only decreased cytoplasmic Mg2+ and Ca2+ inhibition of RyRs. The Ka and maximum levels of cytoplasmic Ca2+ activation site were not affected by ß-adrenergic stimulation. Our RyR2 gating model was fitted to the single channel data. It predicted that in diastole, ß-adrenergic stimulation is mediated by 1) increasing the activating potency of Ca2+ binding to the luminal Ca2+ site and decreasing its affinity for luminal Mg2+ and 2) decreasing affinity of the low-affinity Ca2+/Mg2+ cytoplasmic inhibition site. However in systole, ß-adrenergic stimulation is mediated mainly by the latter.
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Affiliation(s)
- Jiao Li
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Mohammad S. Imtiaz
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Nicole A. Beard
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Angela F. Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Rick Thorne
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Dirk F. vanHelden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Derek R. Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
- * E-mail:
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Sirenko S, Yang D, Li Y, Lyashkov AE, Lukyanenko YO, Lakatta EG, Vinogradova TM. Ca²⁺-dependent phosphorylation of Ca²⁺ cycling proteins generates robust rhythmic local Ca²⁺ releases in cardiac pacemaker cells. Sci Signal 2013; 6:ra6. [PMID: 23362239 DOI: 10.1126/scisignal.2003391] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The spontaneous beating of the heart is governed by spontaneous firing of sinoatrial node cells, which generate action potentials due to spontaneous depolarization of the membrane potential, or diastolic depolarization. The spontaneous diastolic depolarization rate is determined by spontaneous local submembrane Ca²⁺ releases through ryanodine receptors (RyRs). We sought to identify specific mechanisms of intrinsic Ca²⁺ cycling by which sinoatrial node cells, but not ventricular myocytes, generate robust, rhythmic local Ca²⁺ releases. At similar physiological intracellular Ca²⁺ concentrations, local Ca²⁺ releases were large and rhythmic in permeabilized sinoatrial node cells but small and random in permeabilized ventricular myocytes. Furthermore, sinoatrial node cells spontaneously released more Ca²⁺ from the sarcoplasmic reticulum than did ventricular myocytes, despite comparable sarcoplasmic reticulum Ca²⁺ content in both cell types. This ability of sinoatrial node cells to generate larger and rhythmic local Ca²⁺ releases was associated with increased abundance of sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), reduced abundance of the SERCA inhibitor phospholamban, and increased Ca²⁺-dependent phosphorylation of phospholamban and RyR. The increased phosphorylation of RyR in sinoatrial node cells may facilitate Ca²⁺ release from the sarcoplasmic reticulum, whereas Ca²⁺-dependent increase in phosphorylation of phospholamban relieves its inhibition of SERCA, augmenting the pumping rate of Ca²⁺ required to support robust, rhythmic local Ca²⁺ releases. The differences in Ca²⁺ cycling between sinoatrial node cells and ventricular myocytes provide insights into the regulation of intracellular Ca²⁺ cycling that drives the automaticity of sinoatrial node cells.
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Affiliation(s)
- Syevda Sirenko
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging Intramural Research Program, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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FK506 binding proteins: Cellular regulators of intracellular Ca2+ signalling. Eur J Pharmacol 2013; 700:181-93. [DOI: 10.1016/j.ejphar.2012.12.029] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 12/04/2012] [Accepted: 12/18/2012] [Indexed: 02/04/2023]
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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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Niggli E, Ullrich ND, Gutierrez D, Kyrychenko S, Poláková E, Shirokova N. Posttranslational modifications of cardiac ryanodine receptors: Ca(2+) signaling and EC-coupling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:866-75. [PMID: 22960642 DOI: 10.1016/j.bbamcr.2012.08.016] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/18/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
Abstract
In cardiac muscle, a number of posttranslational protein modifications can alter the function of the Ca(2+) release channel of the sarcoplasmic reticulum (SR), also known as the ryanodine receptor (RyR). During every heartbeat RyRs are activated by the Ca(2+)-induced Ca(2+) release mechanism and contribute a large fraction of the Ca(2+) required for contraction. Some of the posttranslational modifications of the RyR are known to affect its gating and Ca(2+) sensitivity. Presently, research in a number of laboratories is focused on RyR phosphorylation, both by PKA and CaMKII, or on RyR modifications caused by reactive oxygen and nitrogen species (ROS/RNS). Both classes of posttranslational modifications are thought to play important roles in the physiological regulation of channel activity, but are also known to provoke abnormal alterations during various diseases. Only recently it was realized that several types of posttranslational modifications are tightly connected and form synergistic (or antagonistic) feed-back loops resulting in additive and potentially detrimental downstream effects. This review summarizes recent findings on such posttranslational modifications, attempts to bridge molecular with cellular findings, and opens a perspective for future work trying to understand the ramifications of crosstalk in these multiple signaling pathways. Clarifying these complex interactions will be important in the development of novel therapeutic approaches, since this may form the foundation for the implementation of multi-pronged treatment regimes in the future. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland.
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