1
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LeMaster DM, Bashir Q, Hernández G. Propagation of conformational instability in FK506-binding protein FKBP12. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2024; 1872:140990. [PMID: 38142946 PMCID: PMC10939819 DOI: 10.1016/j.bbapap.2023.140990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/12/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
FKBP12 is the archetype of the FK506 binding domains that define the family of FKBP proteins which participate in the regulation of various distinct physiological signaling processes. As the drugs FK506 and rapamycin inhibit many of these FKBP proteins, there is need to develop therapeutics which exhibit selectivity within this family. The long β4-β5 loop of the FKBP domain is known to regulate transcriptional activity for the steroid hormone receptors and appears to participate in regulating calcium channel activity for the cardiac and skeletal muscle ryanodine receptors. The β4-β5 loop of FKBP12 has been shown to undergo extensive conformational dynamics, and here we report hydrogen exchange measurements for a series of mutational variants in that loop which indicate deviations from a two-state kinetics for those dynamics. In addition to a previously characterized local transition near the tip of this loop, evidence is presented for a second site of conformational dynamics in the stem of this loop. These mutation-dependent hydrogen exchange effects extend beyond the β4-β5 loop, primarily by disrupting the hydrogen bond between the Gly 58 amide and the Tyr 80 carbonyl oxygen which links the two halves of the structural rim that surrounds the active site cleft. Mutationally-induced opening of the cleft between Gly 58 and Tyr 80 not only modulates the global stability of the protein, it promotes a conformational transition in the distant β2-β3a hairpin that modulates the binding affinity for a FKBP51-selective inhibitor previously designed to exploit a localized conformational transition at the homologous site.
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Affiliation(s)
- David M LeMaster
- Biggs Laboratory Wadsworth Center, NYS Department of Health, Empire State Plaza, Albany, NY 12237, United States of America
| | - Qamar Bashir
- Biggs Laboratory Wadsworth Center, NYS Department of Health, Empire State Plaza, Albany, NY 12237, United States of America
| | - Griselda Hernández
- Biggs Laboratory Wadsworth Center, NYS Department of Health, Empire State Plaza, Albany, NY 12237, United States of America.
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2
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Westhoff M, Del Villar SG, Voelker TL, Thai PN, Spooner HC, Costa AD, Sirish P, Chiamvimonvat N, Dickson EJ, Dixon RE. BIN1 knockdown rescues systolic dysfunction in aging male mouse hearts. Nat Commun 2024; 15:3528. [PMID: 38664444 PMCID: PMC11045846 DOI: 10.1038/s41467-024-47847-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
Cardiac dysfunction is a hallmark of aging in humans and mice. Here we report that a two-week treatment to restore youthful Bridging Integrator 1 (BIN1) levels in the hearts of 24-month-old mice rejuvenates cardiac function and substantially reverses the aging phenotype. Our data indicate that age-associated overexpression of BIN1 occurs alongside dysregulated endosomal recycling and disrupted trafficking of cardiac CaV1.2 and type 2 ryanodine receptors. These deficiencies affect channel function at rest and their upregulation during acute stress. In vivo echocardiography reveals reduced systolic function in old mice. BIN1 knockdown using an adeno-associated virus serotype 9 packaged shRNA-mBIN1 restores the nanoscale distribution and clustering plasticity of ryanodine receptors and recovers Ca2+ transient amplitudes and cardiac systolic function toward youthful levels. Enhanced systolic function correlates with increased phosphorylation of the myofilament protein cardiac myosin binding protein-C. These results reveal BIN1 knockdown as a novel therapeutic strategy to rejuvenate the aging myocardium.
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Affiliation(s)
- Maartje Westhoff
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Silvia G Del Villar
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Taylor L Voelker
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, USA
| | - Heather C Spooner
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Alexandre D Costa
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Padmini Sirish
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, USA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA, USA
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA.
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3
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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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4
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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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5
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Gandon-Renard M, Val-Blasco A, Oughlis C, Gerbaud P, Lefebvre F, Gomez S, Journé C, Courilleau D, Mercier-Nomé F, Pereira L, Benitah JP, Gómez AM, Mercadier JJ. Dual effect of cardiac FKBP12.6 overexpression on excitation-contraction coupling and the incidence of ventricular arrhythmia depending on its expression level. J Mol Cell Cardiol 2024; 188:15-29. [PMID: 38224852 DOI: 10.1016/j.yjmcc.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/17/2024]
Abstract
FKBP12.6, a binding protein to the immunosuppressant FK506, which also binds the ryanodine receptor (RyR2) in the heart, has been proposed to regulate RyR2 function and to have antiarrhythmic properties. However, the level of FKBP12.6 expression in normal hearts remains elusive and some controversies still persist regarding its effects, both in basal conditions and during β-adrenergic stimulation. We quantified FKBP12.6 in the left ventricles (LV) of WT (wild-type) mice and in two novel transgenic models expressing distinct levels of FKBP12.6, using a custom-made specific anti-FKBP12.6 antibody and a recombinant protein. FKBP12.6 level in WT LV was very low (0.16 ± 0.02 nmol/g of LV), indicating that <15% RyR2 monomers are bound to the protein. Mice with 14.1 ± 0.2 nmol of FKBP12.6 per g of LV (TG1) had mild cardiac hypertrophy and normal function and were protected against epinephrine/caffeine-evoked arrhythmias. The ventricular myocytes showed higher [Ca2+]i transient amplitudes than WT myocytes and normal SR-Ca2+ load, while fewer myocytes showed Ca2+ sparks. TG1 cardiomyocytes responded to 50 nM Isoproterenol increasing these [Ca2+]i parameters and producing RyR2-Ser2808 phosphorylation. Mice with more than twice the TG1 FKBP12.6 value (TG2) showed marked cardiac hypertrophy with calcineurin activation and more arrhythmias than WT mice during β-adrenergic stimulation, challenging the protective potential of high FKBP12.6. RyR2R420Q CPVT mice overexpressing FKBP12.6 showed fewer proarrhythmic events and decreased incidence and duration of stress-induced bidirectional ventricular tachycardia. Our study, therefore, quantifies for the first time endogenous FKBP12.6 in the mouse heart, questioning its physiological relevance, at least at rest due its low level. By contrast, our work demonstrates that with caution FKBP12.6 remains an interesting target for the development of new antiarrhythmic therapies.
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Affiliation(s)
- Marine Gandon-Renard
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Almudena Val-Blasco
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Célia Oughlis
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Pascale Gerbaud
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Florence Lefebvre
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Susana Gomez
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Clément Journé
- Fédération de Recherche en Imagerie Multimodale (FRIM), Université Paris Cité, 75018 Paris, France
| | | | - Françoise Mercier-Nomé
- UMS-IPSIT, Université Paris-Saclay, 91400 Orsay, France; Inflammation, Microbiome and Immunosurveillance, Inserm UMR-996, Université Paris-Saclay, 92140 Clamart, France
| | - Laetitia Pereira
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Jean-Pierre Benitah
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France
| | - Ana Maria Gómez
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France.
| | - Jean-Jacques Mercadier
- Signalling and Cardiovascular Pathophysiology, Inserm UMR-S 1180, Université Paris-Saclay, 91400 Orsay, France; Université Paris Cité, Paris, France.
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6
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Tolstik E, Lehnart SE, Soeller C, Lorenz K, Sacconi L. Cardiac multiscale bioimaging: from nano- through micro- to mesoscales. Trends Biotechnol 2024; 42:212-227. [PMID: 37806897 DOI: 10.1016/j.tibtech.2023.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 10/10/2023]
Abstract
Cardiac multiscale bioimaging is an emerging field that aims to provide a comprehensive understanding of the heart and its functions at various levels, from the molecular to the entire organ. It combines both physiologically and clinically relevant dimensions: from nano- and micrometer resolution imaging based on vibrational spectroscopy and high-resolution microscopy to assess molecular processes in cardiac cells and myocardial tissue, to mesoscale structural investigations to improve the understanding of cardiac (patho)physiology. Tailored super-resolution deep microscopy with advanced proteomic methods and hands-on experience are thus strategically combined to improve the quality of cardiovascular research and support future medical decision-making by gaining additional biomolecular information for translational and diagnostic applications.
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Affiliation(s)
- Elen Tolstik
- Department of Cardiovascular Pharmacology, Translational Research, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. Bunsen-Kirchhoff-Strasse 11, 44139 Dortmund, Germany.
| | - Stephan E Lehnart
- Department of Cardiology and Pneumology, Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Georg-August University Göttingen, Robert-Koch-Strasse 42a, 37075 Göttingen, Germany; Cluster of Excellence Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC2067), University of Göttingen, 37073 Göttingen, Germany; Collaborative Research Center SFB1190 Compartmental Gates and Contact Sites in Cells, University of Göttingen, 37073 Göttingen, Germany
| | - Christian Soeller
- Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
| | - Kristina Lorenz
- Department of Cardiovascular Pharmacology, Translational Research, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. Bunsen-Kirchhoff-Strasse 11, 44139 Dortmund, Germany; Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany
| | - Leonardo Sacconi
- Institute of Clinical Physiology, National Research Council, Rome, Italy; Institute for Experimental Cardiovascular Medicine, University Freiburg, Elsässer Strasse 2q, 79110 Freiburg, Germany.
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7
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Waddell HMM, Mereacre V, Alvarado FJ, Munro ML. Clustering properties of the cardiac ryanodine receptor in health and heart failure. J Mol Cell Cardiol 2023; 185:38-49. [PMID: 37890552 PMCID: PMC10717225 DOI: 10.1016/j.yjmcc.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/09/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
The cardiac ryanodine receptor (RyR2) is an intracellular Ca2+ release channel vital for the function of the heart. Physiologically, RyR2 is triggered to release Ca2+ from the sarcoplasmic reticulum (SR) which enables cardiac contraction; however, spontaneous Ca2+ leak from RyR2 has been implicated in the pathophysiology of heart failure (HF). RyR2 channels have been well documented to assemble into clusters within the SR membrane, with the organisation of RyR2 clusters recently gaining interest as a mechanism by which the occurrence of pathological Ca2+ leak is regulated, including in HF. In this review, we explain the terminology relating to key nanoscale RyR2 clustering properties as both single clusters and functionally grouped Ca2+ release units, with a focus on the advancements in super-resolution imaging approaches which have enabled the detailed study of cluster organisation. Further, we discuss proposed mechanisms for modulating RyR2 channel organisation and the debate regarding the potential impact of cluster organisation on Ca2+ leak activity. Finally, recent experimental evidence investigating the nanoscale remodelling and functional alterations of RyR2 clusters in HF is discussed with consideration of the clinical implications.
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Affiliation(s)
- Helen M M Waddell
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Valeria Mereacre
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Francisco J Alvarado
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
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8
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Scriven DR, Johnsen AB, Asghari P, Chou KC, Moore ED. Cardiomyocyte ryanodine receptor clusters expand and coalesce after application of isoproterenol. J Gen Physiol 2023; 155:e202213109. [PMID: 37728575 PMCID: PMC10513110 DOI: 10.1085/jgp.202213109] [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: 09/02/2023] [Indexed: 09/21/2023] Open
Abstract
Earlier work has shown that ventricular ryanodine receptors (RyR2) within a cluster rearrange on phosphorylation as well as with a number of other stimuli. Using dSTORM, we investigated the effects of 300 nmol/liter isoproterenol on RyR2 clusters. In rat ventricular cardiomyocytes, there was a symmetrical enlargement of RyR2 cluster areas, a decrease in the edge-to-edge nearest neighbor distance, and distribution changes that suggested movement to increase the cluster areas by coalescence. The surface area covered by the phosphorylated clusters was significantly greater than in the control cells, as was the cluster density. This latter change was accompanied by a decreased cluster fragmentation, implying that new tetramers were brought into the sarcoplasmic reticulum. We propose a possible mechanism to explain these changes. We also visualized individual RyR2 tetramers and confirmed our earlier electron-tomographic finding that the tetramers are in a disorganized but non-random array occupying about half of the cluster area. Multiclusters, cluster groups defined by the maximum distance between their members, were analyzed for various distances. At 100 nm, the areas occupied by the multiclusters just exceeded those of the single clusters, and more than half of the multiclusters had only a single subcluster that could initiate a spark. Phosphorylation increased the size of the multiclusters, markedly so for distances >100 nm. There was no relationship between the number of subclusters in a group and the area covered by it. We conclude that isoproterenol induces rapid, significant, changes in the molecular architecture of excitation-contraction coupling.
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Affiliation(s)
- David R.L. Scriven
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Anne Berit Johnsen
- Department of Teacher Education, Norwegian University of Science and Technology, Trondheim, Norway
| | - Parisa Asghari
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Keng C. Chou
- Department of Chemistry, University of British Columbia, Vancouver, Canada
| | - Edwin D.W. Moore
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
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9
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Kong CHT, Cannell MB. Ca 2+ spark latency and control of intrinsic Ca 2+ release dyssynchrony in rat cardiac ventricular muscle cells. J Mol Cell Cardiol 2023; 182:44-53. [PMID: 37433391 DOI: 10.1016/j.yjmcc.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/12/2023] [Accepted: 07/06/2023] [Indexed: 07/13/2023]
Abstract
Cardiac excitation-contraction coupling (ECC) depends on Ca2+ release from intracellular stores via ryanodine receptors (RyRs) triggered by L-type Ca2+ channels (LCCs). Uncertain numbers of RyRs and LCCs form 'couplons' whose activation produces Ca2+ sparks, which summate to form a cell-wide Ca2+ transient that switches on contraction. Voltage (Vm) changes during the action potential (AP) and stochasticity in channel gating should create variability in Ca2+ spark timing, but Ca2+ transient wavefronts have remarkable uniformity. To examine how this is achieved, we measured the Vm-dependence of evoked Ca2+ spark probability (Pspark) and latency over a wide voltage range in rat ventricular cells. With depolarising steps, Ca2+ spark latency showed a U-shaped Vm-dependence, while repolarising steps from 50 mV produced Ca2+ spark latencies that increased monotonically with Vm. A computer model based on reported channel gating and geometry reproduced our experimental data and revealed a likely RyR:LCC stoichiometry of ∼ 5:1 for the Ca2+ spark initiating complex (IC). Using the experimental AP waveform, the model revealed a high coupling fidelity (Pcpl ∼ 0.5) between each LCC opening and IC activation. The presence of ∼ 4 ICs per couplon reduced Ca2+ spark latency and increased Pspark to match experimental data. Variability in AP release timing is less than that seen with voltage steps because the AP overshoot and later repolarization decrease Pspark due to effects on LCC flux and LCC deactivation respectively. This work provides a framework for explaining the Vm- and time-dependence of Pspark, and indicates how ion channel dispersion in disease can contribute to dyssynchrony in Ca2+ release.
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Affiliation(s)
- Cherrie H T Kong
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
| | - Mark B Cannell
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
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10
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Dries E, Gilbert G, Roderick HL, Sipido KR. The ryanodine receptor microdomain in cardiomyocytes. Cell Calcium 2023; 114:102769. [PMID: 37390591 DOI: 10.1016/j.ceca.2023.102769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/11/2023] [Accepted: 06/12/2023] [Indexed: 07/02/2023]
Abstract
The ryanodine receptor type 2 (RyR) is a key player in Ca2+ handling during excitation-contraction coupling. During each heartbeat, RyR channels are responsible for linking the action potential with the contractile machinery of the cardiomyocyte by releasing Ca2+ from the sarcoplasmic reticulum. RyR function is fine-tuned by associated signalling molecules, arrangement in clusters and subcellular localization. These parameters together define RyR function within microdomains and are subject to disease remodelling. This review describes the latest findings on RyR microdomain organization, the alterations with disease which result in increased subcellular heterogeneity and emergence of microdomains with enhanced arrhythmogenic potential, and presents novel technologies that guide future research to study and target RyR channels within specific microdomains.
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Affiliation(s)
- Eef Dries
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Guillaume Gilbert
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Laboratoire ORPHY EA 4324, Université de Brest, Brest, France
| | - H Llewelyn Roderick
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Karin R Sipido
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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11
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Grandi E, Navedo MF, Saucerman JJ, Bers DM, Chiamvimonvat N, Dixon RE, Dobrev D, Gomez AM, Harraz OF, Hegyi B, Jones DK, Krogh-Madsen T, Murfee WL, Nystoriak MA, Posnack NG, Ripplinger CM, Veeraraghavan R, Weinberg S. Diversity of cells and signals in the cardiovascular system. J Physiol 2023; 601:2547-2592. [PMID: 36744541 PMCID: PMC10313794 DOI: 10.1113/jp284011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023] Open
Abstract
This white paper is the outcome of the seventh UC Davis Cardiovascular Research Symposium on Systems Approach to Understanding Cardiovascular Disease and Arrhythmia. This biannual meeting aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2022 Symposium was 'Cell Diversity in the Cardiovascular System, cell-autonomous and cell-cell signalling'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies, and challenges in examining cell and signal diversity, co-ordination and interrelationships involved in cardiovascular function. This paper originates from the topics of formal presentations and informal discussions from the Symposium, which aimed to develop a holistic view of how the multiple cell types in the cardiovascular system integrate to influence cardiovascular function, disease progression and therapeutic strategies. The first section describes the major cell types (e.g. cardiomyocytes, vascular smooth muscle and endothelial cells, fibroblasts, neurons, immune cells, etc.) and the signals involved in cardiovascular function. The second section emphasizes the complexity at the subcellular, cellular and system levels in the context of cardiovascular development, ageing and disease. Finally, the third section surveys the technological innovations that allow the interrogation of this diversity and advancing our understanding of the integrated cardiovascular function and dysfunction.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Rose E. Dixon
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Ana M. Gomez
- Signaling and Cardiovascular Pathophysiology-UMR-S 1180, INSERM, Université Paris-Saclay, Orsay, France
| | - Osama F. Harraz
- Department of Pharmacology, Larner College of Medicine, and Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Trine Krogh-Madsen
- Department of Physiology & Biophysics, Weill Cornell Medicine, New York, New York, USA
| | - Walter Lee Murfee
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matthew A. Nystoriak
- Department of Medicine, Division of Environmental Medicine, Center for Cardiometabolic Science, University of Louisville, Louisville, KY, 40202, USA
| | - Nikki G. Posnack
- Department of Pediatrics, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, USA
- Sheikh Zayed Institute for Pediatric and Surgical Innovation, Children’s National Heart Institute, Children’s National Hospital, Washington, DC, USA
| | | | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
| | - Seth Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University – Wexner Medical Center, Columbus, OH, USA
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12
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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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13
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Hurley ME, White E, Sheard TMD, Steele D, Jayasinghe I. Correlative super-resolution analysis of cardiac calcium sparks and their molecular origins in health and disease. Open Biol 2023; 13:230045. [PMID: 37220792 PMCID: PMC10205181 DOI: 10.1098/rsob.230045] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 04/28/2023] [Indexed: 05/25/2023] Open
Abstract
Rapid release of calcium from internal stores via ryanodine receptors (RyRs) is one of the fastest types of cytoplasmic second messenger signalling in excitable cells. In the heart, rapid summation of the elementary events of calcium release, 'calcium sparks', determine the contraction of the myocardium. We adapted a correlative super-resolution microscopy protocol to correlate sub-plasmalemmal spontaneous calcium sparks in rat right ventricular myocytes with the local nanoscale RyR2 positions. This revealed a steep relationship between the integral of a calcium spark and the sum of the local RyR2s. Segmentation of recurring spark sites showed evidence of repeated and triggered saltatory activation of multiple local RyR2 clusters. In myocytes taken from failing right ventricles, RyR2 clusters themselves showed a dissipated morphology and fragmented (smaller) clusters. They also featured greater heterogeneity in both the spark properties and the relationship between the integral of the calcium spark and the local ensemble of RyR2s. While fragmented (smaller) RyR2 clusters were rarely observed directly underlying the larger sparks or the recurring spark sites, local interrogation of the channel-to-channel distances confirmed a clear link between the positions of each calcium spark and the tight, non-random clustering of the local RyR2 in both healthy and failing ventricles.
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Affiliation(s)
- Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas M. D. Sheard
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
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14
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Nakamura J, Maruyama Y, Tajima G, Hayakawa S, Suwa M, Sato C. Ca 2+ Dependent Formation/Collapse of Cylindrical Ca 2+-ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction. Int J Mol Sci 2023; 24:ijms24087080. [PMID: 37108240 PMCID: PMC10139091 DOI: 10.3390/ijms24087080] [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: 12/24/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/29/2023] Open
Abstract
[Ca2+]-dependent crystallization of the Ca2+-ATPase molecules in sarcoplasmic reticulum (SR) vesicles isolated from scallop striated muscle elongated the vesicles in the absence of ATP, and ATP stabilized the crystals. Here, to determine the [Ca2+]-dependence of vesicle elongation in the presence of ATP, SR vesicles in various [Ca2+] environments were imaged using negative stain electron microscopy. The images obtained revealed the following phenomena. (i) Crystal-containing elongated vesicles appeared at ≤1.4 µM Ca2+ and almost disappeared at ≥18 µM Ca2+, where ATPase activity reaches its maximum. (ii) At ≥18 µM Ca2+, almost all SR vesicles were in the round form and covered by tightly clustered ATPase crystal patches. (iii) Round vesicles dried on electron microscopy grids occasionally had cracks, probably because surface tension crushed the solid three-dimensional spheres. (iv) [Ca2+]-dependent ATPase crystallization was rapid (<1 min) and reversible. These data prompt the hypothesis that SR vesicles autonomously elongate or contract with the help of a calcium-sensitive ATPase network/endoskeleton and that ATPase crystallization may modulate physical properties of the SR architecture, including the ryanodine receptors that control muscle contraction.
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Affiliation(s)
- Jun Nakamura
- Health and Medical Institute, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-4 Umezono, Tsukuba 305-8568, Japan
| | - Yuusuke Maruyama
- Health and Medical Institute, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-4 Umezono, Tsukuba 305-8568, Japan
| | - Genichi Tajima
- Institute for Excellence in Higher Education, Tohoku University, 41 Kawauchi, Aoba-ku, Sendai 980-8576, Japan
| | - Satoshi Hayakawa
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
| | - Makiko Suwa
- Biological Science Course, Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuou-ku, Sagamihara 252-5258, Japan
| | - Chikara Sato
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
- Biological Science Course, Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuou-ku, Sagamihara 252-5258, Japan
- Division of Immune Homeostasis, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi, Tokyo 173-8610, Japan
- School of Integrative and Global Majors (SIGMA), University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8577, Japan
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15
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Jin X, Meletiou A, Chung J, Tilunaite A, Demydenko K, Dries E, Puertas RD, Amoni M, Tomar A, Claus P, Soeller C, Rajagopal V, Sipido K, Roderick HL. InsP 3R-RyR channel crosstalk augments sarcoplasmic reticulum Ca 2+ release and arrhythmogenic activity in post-MI pig cardiomyocytes. J Mol Cell Cardiol 2023; 179:47-59. [PMID: 37003353 DOI: 10.1016/j.yjmcc.2023.03.015] [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] [Received: 11/17/2022] [Revised: 03/08/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
Ca2+ transients (CaT) underlying cardiomyocyte (CM) contraction require efficient Ca2+ coupling between sarcolemmal Ca2+ channels and sarcoplasmic reticulum (SR) ryanodine receptor Ca2+ channels (RyR) for their generation; reduced coupling in disease contributes to diminished CaT and arrhythmogenic Ca2+ events. SR Ca2+ release also occurs via inositol 1,4,5-trisphosphate receptors (InsP3R) in CM. While this pathway contributes negligeably to Ca2+ handling in healthy CM, rodent studies support a role in altered Ca2+ dynamics and arrhythmogenic Ca2+ release involving InsP3R crosstalk with RyRs in disease. Whether this mechanism persists in larger mammals with lower T-tubular density and coupling of RyRs is not fully resolved. We have recently shown an arrhythmogenic action of InsP3-induced Ca2+ release (IICR) in end stage human heart failure, often associated with underlying ischemic heart disease (IHD). How IICR contributes to early stages of disease is however not determined but highly relevant. To access this stage, we chose a porcine model of IHD, which shows substantial remodelling of the area adjacent to the infarct. In cells from this region, IICR preferentially augmented Ca2+ release from non-coupled RyR clusters that otherwise showed delayed activation during the CaT. IICR in turn synchronised Ca2+ release during the CaT but also induced arrhythmogenic delayed afterdepolarizations and action potentials. Nanoscale imaging identified co-clustering of InsP3Rs and RyRs, thereby allowing Ca2+-mediated channel crosstalk. Mathematical modelling supported and further delineated this mechanism of enhanced InsP3R-RyRs coupling in MI. Our findings highlight the role of InsP3R-RyR channel crosstalk in Ca2+ release and arrhythmia during post-MI remodelling.
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Affiliation(s)
- Xin Jin
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Anna Meletiou
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Joshua Chung
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium; Cell Structure and Mechanobiology Group, Department of Biomedical Engineering, Melbourne School of Engineering, University of Melbourne, Australia
| | - Agne Tilunaite
- Cell Structure and Mechanobiology Group, Department of Biomedical Engineering, Melbourne School of Engineering, University of Melbourne, Australia; Systems Biology Laboratory, School of Mathematics and Statistics, and Department of Biomedical Engineering, University of Melbourne, Australia
| | - Kateryna Demydenko
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Eef Dries
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Rosa Doñate Puertas
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Matthew Amoni
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Ashutosh Tomar
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - Piet Claus
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | | | - Vijay Rajagopal
- Cell Structure and Mechanobiology Group, Department of Biomedical Engineering, Melbourne School of Engineering, University of Melbourne, Australia
| | - Karin Sipido
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium
| | - H Llewelyn Roderick
- KU Leuven, Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, B-3000 Leuven, Belgium.
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16
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Hou Y, Laasmaa M, Li J, Shen X, Manfra O, Norden ES, Le C, Zhang L, Sjaastad I, Jones PP, Soeller C, Louch WE. Live-cell photo-activated localization microscopy correlates nanoscale ryanodine receptor configuration to calcium sparks in cardiomyocytes. NATURE CARDIOVASCULAR RESEARCH 2023; 2:251-267. [PMID: 38803363 PMCID: PMC7616007 DOI: 10.1038/s44161-022-00199-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/24/2022] [Indexed: 05/29/2024]
Abstract
Ca2+ sparks constitute the fundamental units of Ca2+ release in cardiomyocytes. Here we investigate how ryanodine receptors (RyRs) collectively generate these events by employing a transgenic mouse with a photo-activated label on RyR2. This allowed correlative imaging of RyR localization, by super-resolution Photo-Activated Localization Microscopy, and Ca2+ sparks, by high-speed imaging. Two populations of Ca2+ sparks were observed: stationary events and "travelling" events that spread between neighbouring RyR clusters. Travelling sparks exhibited up to 8 distinct releases, sourced from local or distal junctional sarcoplasmic reticulum. Quantitative analyses showed that sparks may be triggered by any number of RyRs within a cluster, and that acute β-adrenergic stimulation augments intra-cluster RyR recruitment to generate larger events. In contrast, RyR "dispersion" during heart failure facilitates the generation of travelling sparks. Thus, RyRs cooperatively generate Ca2+ sparks in a complex, malleable fashion, and channel organization regulates the propensity for local propagation of Ca2+ release.
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Affiliation(s)
- Yufeng Hou
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Martin Laasmaa
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Ornella Manfra
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Einar S. Norden
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Lili Zhang
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Peter P. Jones
- Department of Physiology, School of Biomedical Sciences and HeartOtago, University of Otago, Dunedin, New Zealand
| | | | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
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17
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Greene D, Luchko T, Shiferaw Y. The role of subunit cooperativity on ryanodine receptor 2 calcium signaling. Biophys J 2023; 122:215-229. [PMID: 36348625 PMCID: PMC9822801 DOI: 10.1016/j.bpj.2022.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/09/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022] Open
Abstract
The ryanodine receptor type 2 (RyR2) is composed of four subunits that control calcium (Ca) release in cardiac cells. RyR2 serves primarily as a Ca sensor and can respond to rapid sub-millisecond pulses of Ca while remaining shut at resting concentrations. However, it is not known how the four subunits interact for the RyR2 to function as an effective Ca sensor. To address this question, and to understand the role of subunit cooperativity in Ca-mediated signal transduction, we have developed a computational model of the RyR2 composed of four interacting subunits. We first analyze the statistical properties of a single RyR2 tetramer, where each subunit can exist in a closed or open conformation. Our findings indicate that the number of subunits in the open state is a crucial parameter that dictates RyR2 kinetics. We find that three or four open subunits are required for the RyR2 to harness cooperative interactions to respond to sub-millisecond changes in Ca, while at the same time remaining shut at the resting Ca levels in the cardiac cell. If the required number of open subunits is lowered to one or two, the RyR2 cannot serve as a robust Ca sensor, as the large cooperativity required to stabilize the closed state prevents channel activation. Using this four-subunit model, we analyze the kinetics of Ca release from a RyR2 cluster. We show that the closure of a cluster of RyR2 channels is highly sensitive to the balance of cooperative interactions between closed and open subunits. Based on this result, we analyze how specific interactions between RyR2 subunits can induce persistent Ca leak from the sarcoplasmic reticulum (SR), which is believed to be arrhythmogenic. Thus, these results provide a framework to analyze how a pharmacologic or genetic modification of RyR2 subunit cooperativity can induce abnormal Ca cycling that can potentially lead to life-threatening arrhythmias.
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Affiliation(s)
- D'Artagnan Greene
- Department of Physics & Astronomy, California State University, Northridge
| | - Tyler Luchko
- Department of Physics & Astronomy, California State University, Northridge
| | - Yohannes Shiferaw
- Department of Physics & Astronomy, California State University, Northridge.
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18
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Louch WE, Ullrich ND, Navedo MF, Macquaide N. Editorial: Nanodomain regulation of muscle physiology and alterations in disease. Front Physiol 2022; 13:1092304. [PMID: 36523550 PMCID: PMC9745436 DOI: 10.3389/fphys.2022.1092304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 11/10/2022] [Indexed: 09/23/2023] Open
Affiliation(s)
- William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
- K. G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Nina D Ullrich
- Institute of Physiology and Pathophysiology, Division of Cardiovascular Physiology, Heidelberg University, Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Heidelberg University, Heidelberg, Germany
| | - Manuel F Navedo
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, United States
| | - Niall Macquaide
- School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
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19
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Sheard TMD, Hurley ME, Smith AJ, Colyer J, White E, Jayasinghe I. Three-dimensional visualization of the cardiac ryanodine receptor clusters and the molecular-scale fraying of dyads. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210316. [PMID: 36189802 PMCID: PMC9527906 DOI: 10.1098/rstb.2021.0316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Clusters of ryanodine receptor calcium channels (RyRs) form the primary molecular machinery of intracellular calcium signalling in cardiomyocytes. While a range of optical super-resolution microscopy techniques have revealed the nanoscale structure of these clusters, the three-dimensional (3D) nanoscale topologies of the clusters have remained mostly unresolved. In this paper, we demonstrate the exploitation of molecular-scale resolution in enhanced expansion microscopy (EExM) along with various 2D and 3D visualization strategies to observe the topological complexities, geometries and molecular sub-domains within the RyR clusters. Notably, we observed sub-domains containing RyR-binding protein junctophilin-2 (JPH2) occupying the central regions of RyR clusters in the deeper interior of the myocytes (including dyads), while the poles were typically devoid of JPH2, lending to a looser RyR arrangement. By contrast, peripheral RyR clusters exhibited variable co-clustering patterns and ratios between RyR and JPH2. EExM images of dyadic RyR clusters in right ventricular (RV) myocytes isolated from rats with monocrotaline-induced RV failure revealed hallmarks of RyR cluster fragmentation accompanied by breaches in the JPH2 sub-domains. Frayed RyR patterns observed adjacent to these constitute new evidence that the destabilization of the RyR arrays inside the JPH2 sub-domains may seed the primordial foci of dyad remodelling observed in heart failure. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Thomas M D Sheard
- School of Biosciences, Faculty of Science, University of Sheffield, Sheffield S10 2TN, UK.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Miriam E Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew J Smith
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - John Colyer
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, University of Sheffield, Sheffield S10 2TN, UK.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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20
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Guarina L, Moghbel AN, Pourhosseinzadeh MS, Cudmore RH, Sato D, Clancy CE, Santana LF. Biological noise is a key determinant of the reproducibility and adaptability of cardiac pacemaking and EC coupling. J Gen Physiol 2022; 154:213185. [PMID: 35482009 PMCID: PMC9059386 DOI: 10.1085/jgp.202012613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/16/2022] [Accepted: 04/07/2022] [Indexed: 12/23/2022] Open
Abstract
Each heartbeat begins with the generation of an action potential in pacemaking cells in the sinoatrial node. This signal triggers contraction of cardiac muscle through a process termed excitation-contraction (EC) coupling. EC coupling is initiated in dyadic structures of cardiac myocytes, where ryanodine receptors in the junctional sarcoplasmic reticulum come into close apposition with clusters of CaV1.2 channels in invaginations of the sarcolemma. Cooperative activation of CaV1.2 channels within these clusters causes a local increase in intracellular Ca2+ that activates the juxtaposed ryanodine receptors. A salient feature of healthy cardiac function is the reliable and precise beat-to-beat pacemaking and amplitude of Ca2+ transients during EC coupling. In this review, we discuss recent discoveries suggesting that the exquisite reproducibility of this system emerges, paradoxically, from high variability at subcellular, cellular, and network levels. This variability is attributable to stochastic fluctuations in ion channel trafficking, clustering, and gating, as well as dyadic structure, which increase intracellular Ca2+ variance during EC coupling. Although the effects of these large, local fluctuations in function and organization are sometimes negligible at the macroscopic level owing to spatial-temporal summation within and across cells in the tissue, recent work suggests that the "noisiness" of these intracellular Ca2+ events may either enhance or counterintuitively reduce variability in a context-dependent manner. Indeed, these noisy events may represent distinct regulatory features in the tuning of cardiac contractility. Collectively, these observations support the importance of incorporating experimentally determined values of Ca2+ variance in all EC coupling models. The high reproducibility of cardiac contraction is a paradoxical outcome of high Ca2+ signaling variability at subcellular, cellular, and network levels caused by stochastic fluctuations in multiple processes in time and space. This underlying stochasticity, which counterintuitively manifests as reliable, consistent Ca2+ transients during EC coupling, also allows for rapid changes in cardiac rhythmicity and contractility in health and disease.
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Affiliation(s)
- Laura Guarina
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Ariana Neelufar Moghbel
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | | | - Robert H Cudmore
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis School of Medicine, Davis, CA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Luis Fernando Santana
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
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21
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Maltsev AV, Stern MD, Maltsev VA. Disorder in Ca2+ release unit locations confers robustness but cuts flexibility of heart pacemaking. J Gen Physiol 2022; 154:213390. [PMID: 35943725 PMCID: PMC9366202 DOI: 10.1085/jgp.202113061] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 05/04/2022] [Accepted: 06/21/2022] [Indexed: 12/12/2022] Open
Abstract
Excitation-contraction coupling kinetics is dictated by the action potential rate of sinoatrial-nodal cells. These cells generate local Ca releases (LCRs) that activate Na/Ca exchanger current, which accelerates diastolic depolarization and determines the pace. LCRs are generated by clusters of ryanodine receptors, Ca release units (CRUs), residing in the sarcoplasmic reticulum. While CRU distribution exhibits substantial heterogeneity, its functional importance remains unknown. Using numerical modeling, here we show that with a square lattice distribution of CRUs, Ca-induced-Ca-release propagation during diastolic depolarization is insufficient for pacemaking within a broad range of realistic ICaL densities. Allowing each CRU to deviate randomly from its lattice position allows sparks to propagate, as observed experimentally. As disorder increases, the CRU distribution exhibits larger empty spaces and simultaneously CRU clusters, as in Poisson clumping. Propagating within the clusters, Ca release becomes synchronized, increasing action potential rate and reviving pacemaker function of dormant/nonfiring cells. However, cells with fully disordered CRU positions could not reach low firing rates and their β-adrenergic-receptor stimulation effect was substantially decreased. Inclusion of Cav1.3, a low-voltage activation L-type Ca channel isoform into ICaL, strongly increases recruitment of CRUs to fire during diastolic depolarization, increasing robustness of pacemaking and complementing effects of CRU distribution. Thus, order/disorder in CRU locations along with Cav1.3 expression regulates pacemaker function via synchronization of CRU firing. Excessive CRU disorder and/or overexpression of Cav1.3 boosts pacemaker function in the basal state, but limits the rate range, which may contribute to heart rate range decline with age and disease.
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Affiliation(s)
- Anna V. Maltsev
- School of Mathematics, Queen Mary University of London, London, UK,Correspondence to Anna V. Maltsev:
| | - Michael D. Stern
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Victor A. Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD,Victor A. Maltsev:
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22
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Shen X, van den Brink J, Bergan-Dahl A, Kolstad TR, Norden ES, Hou Y, Laasmaa M, Aguilar-Sanchez Y, Quick AP, Espe EKS, Sjaastad I, Wehrens XHT, Edwards AG, Soeller C, Louch WE. Prolonged β-adrenergic stimulation disperses ryanodine receptor clusters in cardiomyocytes. eLife 2022; 11:77725. [PMID: 35913125 PMCID: PMC9410709 DOI: 10.7554/elife.77725] [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: 02/15/2022] [Accepted: 07/31/2022] [Indexed: 11/17/2022] Open
Abstract
Ryanodine receptors (RyRs) exhibit dynamic arrangements in cardiomyocytes, and we previously showed that ‘dispersion’ of RyR clusters disrupts Ca2+ homeostasis during heart failure (HF) (Kolstad et al., eLife, 2018). Here, we investigated whether prolonged β-adrenergic stimulation, a hallmark of HF, promotes RyR cluster dispersion and examined the underlying mechanisms. We observed that treatment of healthy rat cardiomyocytes with isoproterenol for 1 hr triggered progressive fragmentation of RyR clusters. Pharmacological inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) reversed these effects, while cluster dispersion was reproduced by specific activation of CaMKII, and in mice with constitutively active Ser2814-RyR. A similar role of protein kinase A (PKA) in promoting RyR cluster fragmentation was established by employing PKA activation or inhibition. Progressive cluster dispersion was linked to declining Ca2+ spark fidelity and magnitude, and slowed release kinetics from Ca2+ propagation between more numerous RyR clusters. In healthy cells, this served to dampen the stimulatory actions of β-adrenergic stimulation over the longer term and protect against pro-arrhythmic Ca2+ waves. However, during HF, RyR dispersion was linked to impaired Ca2+ release. Thus, RyR localization and function are intimately linked via channel phosphorylation by both CaMKII and PKA, which, while finely tuned in healthy cardiomyocytes, underlies impaired cardiac function during pathology.
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Affiliation(s)
- Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | | | - Anna Bergan-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Terje R Kolstad
- Insitute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | | | - Yufeng Hou
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Martin Laasmaa
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Yuriana Aguilar-Sanchez
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | - Ann Pepper Quick
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | | | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, United States
| | | | | | - William Edward Louch
- Institute for Experimental Medical Research, Oslo University Hospital, Oslo, Norway
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23
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Hernández Mesa M, van den Brink J, Louch WE, McCabe KJ, Rangamani P. Nanoscale organization of ryanodine receptor distribution and phosphorylation pattern determines the dynamics of calcium sparks. PLoS Comput Biol 2022; 18:e1010126. [PMID: 35666763 PMCID: PMC9203011 DOI: 10.1371/journal.pcbi.1010126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 06/16/2022] [Accepted: 04/20/2022] [Indexed: 11/18/2022] Open
Abstract
Super-resolution imaging techniques have provided a better understanding of the relationship between the nanoscale organization and function of ryanodine receptors (RyRs) in cardiomyocytes. Recent data have indicated that this relationship is disrupted in heart failure (HF), as RyRs are dispersed into smaller and more numerous clusters. However, RyRs are also hyperphosphorylated in this condition, and this is reported to occur preferentially within the cluster centre. Thus, the combined impact of RyR relocalization and sensitization on Ca2+ spark generation in failing cardiomyocytes is likely complex and these observations suggest that both the nanoscale organization of RyRs and the pattern of phosphorylated RyRs within clusters could be critical determinants of Ca2+ spark dynamics. To test this hypothesis, we used computational modeling to quantify the relationships between RyR cluster geometry, phosphorylation patterns, and sarcoplasmic reticulum (SR) Ca2+ release. We found that RyR cluster disruption results in a decrease in spark fidelity and longer sparks with a lower amplitude. Phosphorylation of some RyRs within the cluster can play a compensatory role, recovering healthy spark dynamics. Interestingly, our model predicts that such compensation is critically dependent on the phosphorylation pattern, as phosphorylation localized within the cluster center resulted in longer Ca2+ sparks and higher spark fidelity compared to a uniformly distributed phosphorylation pattern. Our results strongly suggest that both the phosphorylation pattern and nanoscale RyR reorganization are critical determinants of Ca2+ dynamics in HF. Ryanodine receptors (RyRs) are ion channels located on the membrane of the sarcoplasmic reticulum that are responsible for an increase in cytosolic Ca2+ during cell excitation. Here, we investigate how the geometry of RyR clusters combined with spatial phosphorylation patterns impacts on Ca2+ spark generation and kinetics. The findings from our study show that phosphorylation pattern and both RyR cluster shape and dispersion have implications on Ca2+ spark activity and provide insights into altered Ca2+ dynamics during HF.
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Affiliation(s)
- María Hernández Mesa
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - Jonas van den Brink
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Kimberly J. McCabe
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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24
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Hadiatullah H, He Z, Yuchi Z. Structural Insight Into Ryanodine Receptor Channelopathies. Front Pharmacol 2022; 13:897494. [PMID: 35677449 PMCID: PMC9168041 DOI: 10.3389/fphar.2022.897494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/09/2022] [Indexed: 11/28/2022] Open
Abstract
The ryanodine receptors (RyRs) are large cation-selective ligand-gated channels that are expressed in the sarcoplasmic reticulum (SR) membrane. They mediate the controlled release of Ca2+ from SR and play an important role in many cellular processes. The mutations in RyRs are associated with several skeletal muscle and cardiac conditions, including malignant hyperthermia (MH), central core disease (CCD), catecholaminergic polymorphic ventricular tachycardia (CPVT), and arrhythmogenic right ventricular dysplasia (ARVD). Recent breakthroughs in structural biology including cryo-electron microscopy (EM) and X-ray crystallography allowed the determination of a number of near-atomic structures of RyRs, including wildtype and mutant structures as well as the structures in complex with different modulating molecules. This allows us to comprehend the physiological gating and regulatory mechanisms of RyRs and the underlying pathological mechanisms of the disease-causing mutations. In this review, based on the insights gained from the available high-resolution structures of RyRs, we address several questions: 1) what are the gating mechanisms of different RyR isoforms; 2) how RyRs are regulated by multiple channel modulators, including ions, small molecules, and regulatory proteins; 3) how do disease-causing mutations affect the structure and function of RyRs; 4) how can these structural information aid in the diagnosis of the related diseases and the development of pharmacological therapies.
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Affiliation(s)
- Hadiatullah Hadiatullah
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
- Department of Molecular Pharmacology, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Zhao He
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
- Department of Molecular Pharmacology, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Zhiguang Yuchi
- Tianjin Key Laboratory for Modern Drug Delivery and High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
- Department of Molecular Pharmacology, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- *Correspondence: Zhiguang Yuchi,
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25
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Kohl P, Greiner J, Rog-Zielinska EA. Electron microscopy of cardiac 3D nanodynamics: form, function, future. Nat Rev Cardiol 2022; 19:607-619. [PMID: 35396547 DOI: 10.1038/s41569-022-00677-x] [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] [Accepted: 02/04/2022] [Indexed: 11/09/2022]
Abstract
The 3D nanostructure of the heart, its dynamic deformation during cycles of contraction and relaxation, and the effects of this deformation on cell function remain largely uncharted territory. Over the past decade, the first inroads have been made towards 3D reconstruction of heart cells, with a native resolution of around 1 nm3, and of individual molecules relevant to heart function at a near-atomic scale. These advances have provided access to a new generation of data and have driven the development of increasingly smart, artificial intelligence-based, deep-learning image-analysis algorithms. By high-pressure freezing of cardiomyocytes with millisecond accuracy after initiation of an action potential, pseudodynamic snapshots of contraction-induced deformation of intracellular organelles can now be captured. In combination with functional studies, such as fluorescence imaging, exciting insights into cardiac autoregulatory processes at nano-to-micro scales are starting to emerge. In this Review, we discuss the progress in this fascinating new field to highlight the fundamental scientific insight that has emerged, based on technological breakthroughs in biological sample preparation, 3D imaging and data analysis; to illustrate the potential clinical relevance of understanding 3D cardiac nanodynamics; and to predict further progress that we can reasonably expect to see over the next 10 years.
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Affiliation(s)
- Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Engineering, University of Freiburg, Freiburg, Germany.,Centre for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, Freiburg, Germany
| | - Joachim Greiner
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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26
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Preserved cardiac performance and adrenergic response in a rabbit model with decreased ryanodine receptor 2 expression. J Mol Cell Cardiol 2022; 167:118-128. [DOI: 10.1016/j.yjmcc.2022.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/11/2022] [Accepted: 04/06/2022] [Indexed: 11/19/2022]
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Demydenko K, Roderick HL. The cardiomyocyte firestarter-RyR clusters ignite their neighbours after augmentation of Ca 2+ release by β-stimulation. Acta Physiol (Oxf) 2022; 234:e13798. [PMID: 35147280 DOI: 10.1111/apha.13798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/01/2022] [Accepted: 02/08/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Kateryna Demydenko
- Laboratory of Experimental Cardiology Department of Cardiovascular Sciences KU Leuven Leuven Belgium
| | - H. Llewelyn Roderick
- Laboratory of Experimental Cardiology Department of Cardiovascular Sciences KU Leuven Leuven Belgium
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28
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Louch WE, Perdreau-Dahl H, Edwards AG. Image-Driven Modeling of Nanoscopic Cardiac Function: Where Have We Come From, and Where Are We Going? Front Physiol 2022; 13:834211. [PMID: 35356084 PMCID: PMC8959215 DOI: 10.3389/fphys.2022.834211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/24/2022] Open
Abstract
Complementary developments in microscopy and mathematical modeling have been critical to our understanding of cardiac excitation–contraction coupling. Historically, limitations imposed by the spatial or temporal resolution of imaging methods have been addressed through careful mathematical interrogation. Similarly, limitations imposed by computational power have been addressed by imaging macroscopic function in large subcellular domains or in whole myocytes. As both imaging resolution and computational tractability have improved, the two approaches have nearly merged in terms of the scales that they can each be used to interrogate. With this review we will provide an overview of these advances and their contribution to understanding ventricular myocyte function, including exciting developments over the last decade. We specifically focus on experimental methods that have pushed back limits of either spatial or temporal resolution of nanoscale imaging (e.g., DNA-PAINT), or have permitted high resolution imaging on large cellular volumes (e.g., serial scanning electron microscopy). We also review the progression of computational approaches used to integrate and interrogate these new experimental data sources, and comment on near-term advances that may unify understanding of the underlying biology. Finally, we comment on several outstanding questions in cardiac physiology that stand to benefit from a concerted and complementary application of these new experimental and computational methods.
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Affiliation(s)
- William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Harmonie Perdreau-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Andrew G. Edwards
- Simula Research Laboratory, Lysaker, Norway
- *Correspondence: Andrew G. Edwards,
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Abstract
In mammalian cardiac myocytes, the plasma membrane includes the surface sarcolemma but also a network of membrane invaginations called transverse (t-) tubules. These structures carry the action potential deep into the cell interior, allowing efficient triggering of Ca2+ release and initiation of contraction. Once thought to serve as rather static enablers of excitation-contraction coupling, recent work has provided a newfound appreciation of the plasticity of the t-tubule network's structure and function. Indeed, t-tubules are now understood to support dynamic regulation of the heartbeat across a range of timescales, during all stages of life, in both health and disease. This review article aims to summarize these concepts, with consideration given to emerging t-tubule regulators and their targeting in future therapies.
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Affiliation(s)
- Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom;
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom;
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30
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Dixon RE. Nanoscale Organization, Regulation, and Dynamic Reorganization of Cardiac Calcium Channels. Front Physiol 2022; 12:810408. [PMID: 35069264 PMCID: PMC8769284 DOI: 10.3389/fphys.2021.810408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 11/30/2021] [Indexed: 12/19/2022] Open
Abstract
The architectural specializations and targeted delivery pathways of cardiomyocytes ensure that L-type Ca2+ channels (CaV1.2) are concentrated on the t-tubule sarcolemma within nanometers of their intracellular partners the type 2 ryanodine receptors (RyR2) which cluster on the junctional sarcoplasmic reticulum (jSR). The organization and distribution of these two groups of cardiac calcium channel clusters critically underlies the uniform contraction of the myocardium. Ca2+ signaling between these two sets of adjacent clusters produces Ca2+ sparks that in health, cannot escalate into Ca2+ waves because there is sufficient separation of adjacent clusters so that the release of Ca2+ from one RyR2 cluster or supercluster, cannot activate and sustain the release of Ca2+ from neighboring clusters. Instead, thousands of these Ca2+ release units (CRUs) generate near simultaneous Ca2+ sparks across every cardiomyocyte during the action potential when calcium induced calcium release from RyR2 is stimulated by depolarization induced Ca2+ influx through voltage dependent CaV1.2 channel clusters. These sparks summate to generate a global Ca2+ transient that activates the myofilaments and thus the electrical signal of the action potential is transduced into a functional output, myocardial contraction. To generate more, or less contractile force to match the hemodynamic and metabolic demands of the body, the heart responds to β-adrenergic signaling by altering activity of calcium channels to tune excitation-contraction coupling accordingly. Recent accumulating evidence suggests that this tuning process also involves altered expression, and dynamic reorganization of CaV1.2 and RyR2 channels on their respective membranes to control the amplitude of Ca2+ entry, SR Ca2+ release and myocardial function. In heart failure and aging, altered distribution and reorganization of these key Ca2+ signaling proteins occurs alongside architectural remodeling and is thought to contribute to impaired contractile function. In the present review we discuss these latest developments, their implications, and future questions to be addressed.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, United States
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31
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Wilson AD, Hu J, Sigalas C, Venturi E, Valdivia HH, Valdivia CR, Lei M, Musgaard M, Sitsapesan R. The V2475F CPVT1 mutation yields distinct RyR2 channel populations that differ in their responses to cytosolic Ca 2+ and Mg 2. J Physiol 2021; 599:5179-5201. [PMID: 34676560 DOI: 10.1113/jp281707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 09/30/2021] [Indexed: 11/08/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1) is a lethal genetic disease causing arrhythmias and sudden cardiac death in children and young adults and is linked to mutations in the cardiac ryanodine receptor (RyR2). The effects of CPVT1 mutations on RyR2 ion-channel function are often investigated using purified recombinant RyR2 channels homozygous for the mutation. However, CPVT1 patients are heterozygous for the disease, so this approach does not reveal the true changes to RyR2 function across the entire RyR2 population of channels in the heart. We therefore investigated the native cardiac RyR2 single-channel abnormalities in mice heterozygous for the CPVT1 mutation, V2475F(+/-)-RyR2, and applied molecular modelling techniques to investigate the possible structural changes that could initiate any altered function. We observed that increased sensitivity of cardiac V2475F(+/-)-RyR2 channels to both activating and inactivating levels of cytosolic Ca2+ , plus attenuation of Mg2+ inhibition, were the most marked changes. Severity of abnormality was not uniform across all channels, giving rise to multiple sub-populations with differing functional characteristics. For example, 46% of V2475F(+/-)-RyR2 channels exhibited reduced Mg2+ inhibition and 23% were actually activated by Mg2+ . Using homology modelling, we discovered that V2475 is situated at a hinge between two regions of the RyR2 helical domain 1 (HD1). Our model proposes that detrimental functional changes to RyR2 arise because mutation at this critical site reduces the angle between these regions. Our results demonstrate the necessity of characterising the total heterozygous population of CPVT1-mutated channels in order to understand CPVT1 phenotypes in patients. KEY POINTS: RyR2 mutations can cause type-1 catecholaminergic polymorphic ventricular tachycardia (CPVT1), a lethal, autosomal-dominant arrhythmic disease. However, the changes in RyR2 ion-channel function that result from the many different patient mutations are rarely investigated in detail and often only recombinant RyR2, homozygous for the mutation, is studied. As CPVT1 is a heterozygous disease and the tetrameric RyR2 channels expressed in the heart will contain varying numbers of mutated monomers, we have investigated the range of RyR2 single-channel abnormalities found in the hearts of mice heterozygous for the CPVT1 mutation, V2475F(+/-)-RyR2. Specific alterations to ligand regulation of V2475F(+/-)-RyR2 were observed. Multiple sub-populations of channels exhibited varying degrees of abnormality. In particular, an increased sensitivity to activating and inactivating cytosolic [Ca2+ ], and reduced sensitivity to Mg2+ inhibition were evident. Our results provide mechanistic insight into the changes to RyR2 gating that destabilise sarcoplasmic reticulum Ca2+ -release causing life-threatening arrhythmias in V2475F(+/-)-CPVT1 patients.
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Affiliation(s)
| | - Jianshu Hu
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | - Elisa Venturi
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Héctor H Valdivia
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, USA
| | - Carmen R Valdivia
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, USA
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Maria Musgaard
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
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32
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Janicek R, Agarwal H, Gómez AM, Egger M, Ellis-Davies GCR, Niggli E. Local recovery of cardiac calcium-induced calcium release interrogated by ultra-effective, two-photon uncaging of calcium. J Physiol 2021; 599:3841-3852. [PMID: 34245001 PMCID: PMC8456848 DOI: 10.1113/jp281482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 07/09/2021] [Indexed: 11/09/2022] Open
Abstract
Key points In cardiac myocytes, subcellular local calcium release signals, calcium sparks, are recruited to form each cellular calcium transient and activate the contractile machinery. Abnormal timing of recovery of sparks after their termination may contribute to arrhythmias. We developed a method to interrogate recovery of calcium spark trigger probabilities and their amplitude over time using two‐photon photolysis of a new ultra‐effective caged calcium compound. The findings confirm the utility of the technique to define an elevated sensitivity of the calcium release mechanism in situ and to follow hastened recovery of spark trigger probabilities in a mouse model of an inherited cardiac arrhythmia, which was used for validation. Analogous methods are likely to be applicable to investigate other microscopic subcellular signalling systems in a variety of cell types.
Abstract In cardiac myocytes Ca2+‐induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR) through ryanodine receptors (RyRs) governs activation of contraction. Ca2+ release occurs via subcellular Ca2+ signalling events, Ca2+ sparks. Local recovery of Ca2+ release depends on both SR refilling and restoration of Ca2+ sensitivity of the RyRs. We used two‐photon (2P) photolysis of the ultra‐effective caged Ca2+ compound BIST‐2EGTA and laser‐scanning confocal Ca2+ imaging to probe refractoriness of local Ca2+ release in control conditions and in the presence of cAMP or low‐dose caffeine (to stimulate CICR) or cyclopiazonic acid (CPA; to slow SR refilling). Permeabilized cardiomyocytes were loaded with BIST‐2EGTA and rhod‐2. Pairs of short 2P photolytic pulses (1 ms, 810 nm) were applied with different intervals to test Ca2+ release amplitude recovery and trigger probability for the second spark in a pair. Photolytic and biological events were distinguished by classification with a self‐learning support vector machine (SVM) algorithm. In permeabilized myocytes data recorded in the presence of CPA showed a lower probability of triggering a second spark compared to control or cAMP conditions. Cardiomyocytes from a mouse model harbouring the arrhythmogenic RyRR420Q mutation were used for further validation and revealed a higher Ca2+ sensitivity of CICR. This new 2P approach provides composite information of Ca2+ release amplitude and trigger probability recovery reflecting both SR refilling and restoration of CICR and RyR Ca2+ sensitivity. It can be used to measure the kinetics of local CICR recovery, alterations of which may be related to premature heart beats and arrhythmias. In cardiac myocytes, subcellular local calcium release signals, calcium sparks, are recruited to form each cellular calcium transient and activate the contractile machinery. Abnormal timing of recovery of sparks after their termination may contribute to arrhythmias. We developed a method to interrogate recovery of calcium spark trigger probabilities and their amplitude over time using two‐photon photolysis of a new ultra‐effective caged calcium compound. The findings confirm the utility of the technique to define an elevated sensitivity of the calcium release mechanism in situ and to follow hastened recovery of spark trigger probabilities in a mouse model of an inherited cardiac arrhythmia, which was used for validation. Analogous methods are likely to be applicable to investigate other microscopic subcellular signalling systems in a variety of cell types.
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Affiliation(s)
| | - Hitesh Agarwal
- Department of Neuroscience, Mount Sinai School of Medicine, New York, NY, USA
| | - Ana M Gómez
- Signaling and cardiovascular pathophysiology - UMR-S 1180, Inserm, Université Paris-Saclay, Châtenay-Malabry, France
| | - Marcel Egger
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland
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33
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Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
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Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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34
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Gilani N, Wang K, Muncan A, Peter J, An S, Bhatti S, Pandya K, Zhang Y, Tang YD, Gerdes AM, Stout RF, Ojamaa K. Triiodothyronine maintains cardiac transverse-tubule structure and function. J Mol Cell Cardiol 2021; 160:1-14. [PMID: 34175303 DOI: 10.1016/j.yjmcc.2021.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 06/03/2021] [Accepted: 06/18/2021] [Indexed: 12/29/2022]
Abstract
Subclinical hypothyroidism and low T3 syndrome are commonly associated with an increased risk of cardiovascular disease (CVD) and mortality. We examined effects of T3 on T-tubule (TT) structures, Ca2+ mobilization and contractility, and clustering of dyadic proteins. Thyroid hormone (TH) deficiency was induced in adult female rats by propyl-thiouracil (PTU; 0.025%) treatment for 8 weeks. Rats were then randomized to continued PTU or triiodo-L-thyronine (T3; 10 μg/kg/d) treatment for 2 weeks (PTU + T3). After in vivo echocardiographic and hemodynamic recordings, cardiomyocytes (CM) were isolated to record Ca2+ transients and contractility. TT organization was assessed by confocal microscopy, and STORM images were captured to measure ryanodine receptor (RyR2) cluster number and size, and L-type Ca2+ channel (LTCC, Cav1.2) co-localization. Expressed genes including two integral TT proteins, junctophilin-2 (Jph-2) and bridging integrator-1 (BIN1), were analyzed in left ventricular (LV) tissues and cultured CM using qPCR and RNA sequencing. The T3 dosage used normalized serum T3, and reversed adverse effects of TH deficiency on in vivo measures of cardiac function. Recordings of isolated CM indicated that T3 increased rates of Ca2+ release and re-uptake, resulting in increased velocities of sarcomere shortening and re-lengthening. TT periodicity was significantly decreased, with reduced transverse tubules but increased longitudinal tubules in TH-deficient CMs and LV tissue, and these structures were normalized by T3 treatment. Analysis of STORM data of PTU myocytes showed decreased RyR2 cluster numbers and RyR localizations within each cluster without significant changes in Cav1.2 localizations within RyR clusters. T3 treatment normalized RyR2 cluster size and number. qPCR and RNAseq analyses of LV and cultured CM showed that Jph2 expression was T3-responsive, and its increase with treatment may explain improved TT organization and RyR-LTCC coupling.
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Affiliation(s)
- Nimra Gilani
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Kaihao Wang
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA; Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Adam Muncan
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Jerrin Peter
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Shimin An
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA; Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Simran Bhatti
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Khushbu Pandya
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Youhua Zhang
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Yi-Da Tang
- Department of Cardiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - A Martin Gerdes
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Randy F Stout
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA; NYIT Imaging Center, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
| | - Kaie Ojamaa
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Northern Blvd., Old Westbury, New York 11568, USA.
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Iaparov BI, Zahradnik I, Moskvin AS, Zahradníková A. In silico simulations reveal that RYR distribution affects the dynamics of calcium release in cardiac myocytes. J Gen Physiol 2021; 153:211900. [PMID: 33735373 PMCID: PMC7980188 DOI: 10.1085/jgp.202012685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 02/08/2021] [Indexed: 11/20/2022] Open
Abstract
The dyads of cardiac myocytes contain ryanodine receptors (RYRs) that generate calcium sparks upon activation. To test how geometric factors of RYR distribution contribute to the formation of calcium sparks, which cannot be addressed experimentally, we performed in silico simulations on a large set of models of calcium release sites (CRSs). Our models covered the observed range of RYR number, density, and spatial arrangement. The calcium release function of CRSs was modeled by RYR openings, with an open probability dependent on concentrations of free Ca2+ and Mg2+ ions, in a rapidly buffered system, with a constant open RYR calcium current. We found that simulations of spontaneous sparks by repeatedly opening one of the RYRs in a CRS produced three different types of calcium release events (CREs) in any of the models. Transformation of simulated CREs into fluorescence signals yielded calcium sparks with characteristics close to the observed ones. CRE occurrence varied broadly with the spatial distribution of RYRs in the CRS but did not consistently correlate with RYR number, surface density, or calcium current. However, it correlated with RYR coupling strength, defined as the weighted product of RYR vicinity and calcium current, so that CRE characteristics of all models followed the same state-response function. This finding revealed the synergy between structure and function of CRSs in shaping dyad function. Lastly, rearrangements of RYRs simulating hypothetical experiments on splitting and compaction of a dyad revealed an increased propensity to generate spontaneous sparks and an overall increase in calcium release in smaller and more compact dyads, thus underlying the importance and physiological role of RYR arrangement in cardiac myocytes.
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Affiliation(s)
- Bogdan I Iaparov
- Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia.,Research Institute of Physics and Applied Mathematics, and Department of Theoretical and Mathematical Physics, Ural Federal University, Ekaterinburg, Russia
| | - Ivan Zahradnik
- Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Alexander S Moskvin
- Research Institute of Physics and Applied Mathematics, and Department of Theoretical and Mathematical Physics, Ural Federal University, Ekaterinburg, Russia
| | - Alexandra Zahradníková
- Department of Cellular Cardiology, Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
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Munro ML, van Hout I, Aitken-Buck HM, Sugunesegran R, Bhagwat K, Davis PJ, Lamberts RR, Coffey S, Soeller C, Jones PP. Human Atrial Fibrillation Is Not Associated With Remodeling of Ryanodine Receptor Clusters. Front Cell Dev Biol 2021; 9:633704. [PMID: 33718369 PMCID: PMC7947344 DOI: 10.3389/fcell.2021.633704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/08/2021] [Indexed: 12/02/2022] Open
Abstract
The release of Ca2+ by ryanodine receptor (RyR2) channels is critical for cardiac function. However, abnormal RyR2 activity has been linked to the development of arrhythmias, including increased spontaneous Ca2+ release in human atrial fibrillation (AF). Clustering properties of RyR2 have been suggested to alter the activity of the channel, with remodeling of RyR2 clusters identified in pre-clinical models of AF and heart failure. Whether such remodeling occurs in human cardiac disease remains unclear. This study aimed to investigate the nanoscale organization of RyR2 clusters in AF patients – the first known study to examine this potential remodeling in diseased human cardiomyocytes. Right atrial appendage from cardiac surgery patients with paroxysmal or persistent AF, or without AF (non-AF) were examined using super-resolution (dSTORM) imaging. Significant atrial dilation and cardiomyocyte hypertrophy was observed in persistent AF patients compared to non-AF, with these two parameters significantly correlated. Interestingly, the clustering properties of RyR2 were remarkably unaltered in the AF patients. No significant differences were identified in cluster size (mean ∼18 RyR2 channels), density or channel packing within clusters between patient groups. The spatial organization of clusters throughout the cardiomyocyte was also unchanged across the groups. RyR2 clustering properties did not significantly correlate with patient characteristics. In this first study to examine nanoscale RyR2 organization in human cardiac disease, these findings indicate that RyR2 cluster remodeling is not an underlying mechanism contributing to altered channel function and subsequent arrhythmogenesis in human AF.
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Affiliation(s)
- Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Isabelle van Hout
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Hamish M Aitken-Buck
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | | | - Krishna Bhagwat
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Philip J Davis
- Department of Cardiothoracic Surgery, Dunedin Hospital, Dunedin, New Zealand
| | - Regis R Lamberts
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sean Coffey
- Department of Medicine and HeartOtago, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Christian Soeller
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Peter P Jones
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Gong D, Yan N, Ledford HA. Structural Basis for the Modulation of Ryanodine Receptors. Trends Biochem Sci 2020; 46:489-501. [PMID: 33353849 DOI: 10.1016/j.tibs.2020.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/16/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022]
Abstract
Historically, ryanodine receptors (RyRs) have presented unique challenges for high-resolution structural determination despite long-standing interest in their role in excitation-contraction coupling. Owing to their large size (nearly 2.2 MDa), high-resolution structures remained elusive until the advent of cryogenic electron microscopy (cryo-EM) techniques. In recent years, structures for both RyR1 and RyR2 have been solved at near-atomic resolution. Furthermore, recent reports have delved into their more complex structural associations with key modulators - proteins such as the dihydropyridine receptor (DHPR), FKBP12/12.6, and calmodulin (CaM), as well as ions and small molecules including Ca2+, ATP, caffeine, and PCB95. This review addresses the modulation of RyR1 and RyR2, in addition to the impact of such discoveries on intracellular Ca2+ dynamics and biophysical properties.
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Affiliation(s)
- Deshun Gong
- Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province/Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, Zhejiang, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, Zhejiang Province, China.
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Hannah A Ledford
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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