1
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Naumenko N, Koivumäki JT, Lunko O, Tuomainen T, Leigh R, Rabiee M, Laurila J, Oksanen M, Lehtonen S, Koistinaho J, Tavi P. Presenilin-1 ΔE9 mutation associated sarcoplasmic reticulum leak alters [Ca 2+] i distribution in human iPSC-derived cardiomyocytes. J Mol Cell Cardiol 2024; 193:78-87. [PMID: 38851626 DOI: 10.1016/j.yjmcc.2024.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 05/28/2024] [Accepted: 06/04/2024] [Indexed: 06/10/2024]
Abstract
Mutations in ubiquitously expressed presenilin genes (PSENs) lead to early-onset familial Alzheimer's disease (FAD), but patients carrying the mutation also suffer from heart diseases. To elucidate the cardiac myocyte specific effects of PSEN ΔE9, we studied cardiomyocytes derived from induced pluripotent stem cells (iPSC-CMs) from patients carrying AD-causing PSEN1 exon 9 deletion (PSEN1 ΔE9). When compared with their isogenic controls, PSEN1 ΔE9 cardiomyocytes showed increased sarcoplasmic reticulum (SR) Ca2+ leak that was resistant to blockage of ryanodine receptors (RyRs) by tetracaine or inositol-3-reseceptors (IP3Rs) by 2-ABP. The SR Ca2+ leak did not affect electrophysiological properties of the hiPSC-CMs, but according to experiments and in silico simulations the leak induces a diastolic buildup of [Ca2+] near the perinuclear SR and reduces the releasable Ca2+ during systole. This demonstrates that PSEN1 ΔE9 induced SR Ca2+ leak has specific effects in iPSC-CMs, reflecting their unique structural and calcium signaling features. The results shed light on the physiological and pathological mechanisms of PSEN1 in cardiac myocytes and explain the intricacies of comorbidity associated with AD-causing mutations in PSEN1.
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Affiliation(s)
- Nikolay Naumenko
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jussi T Koivumäki
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Olesia Lunko
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Tomi Tuomainen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Robert Leigh
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Mina Rabiee
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jalmari Laurila
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Minna Oksanen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Sarka Lehtonen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Jari Koistinaho
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Pasi Tavi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
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2
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Bovo E, Seflova J, Robia SL, Zima AV. Protein carbonylation causes sarcoplasmic reticulum Ca 2+ overload by increasing intracellular Na + level in ventricular myocytes. Pflugers Arch 2024; 476:1077-1086. [PMID: 38769127 DOI: 10.1007/s00424-024-02972-7] [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: 02/26/2024] [Revised: 04/22/2024] [Accepted: 05/15/2024] [Indexed: 05/22/2024]
Abstract
Diabetes is commonly associated with an elevated level of reactive carbonyl species due to alteration of glucose and fatty acid metabolism. These metabolic changes cause an abnormality in cardiac Ca2+ regulation that can lead to cardiomyopathies. In this study, we explored how the reactive α-dicarbonyl methylglyoxal (MGO) affects Ca2+ regulation in mouse ventricular myocytes. Analysis of intracellular Ca2+ dynamics revealed that MGO (200 μM) increases action potential (AP)-induced Ca2+ transients and sarcoplasmic reticulum (SR) Ca2+ load, with a limited effect on L-type Ca2+ channel-mediated Ca2+ transients and SERCA-mediated Ca2+ uptake. At the same time, MGO significantly slowed down cytosolic Ca2+ extrusion by Na+/Ca2+ exchanger (NCX). MGO also increased the frequency of Ca2+ waves during rest and these Ca2+ release events were abolished by an external solution with zero [Na+] and [Ca2+]. Adrenergic receptor activation with isoproterenol (10 nM) increased Ca2+ transients and SR Ca2+ load, but it also triggered spontaneous Ca2+ waves in 27% of studied cells. Pretreatment of myocytes with MGO increased the fraction of cells with Ca2+ waves during adrenergic receptor stimulation by 163%. Measurements of intracellular [Na+] revealed that MGO increases cytosolic [Na+] by 57% from the maximal effect produced by the Na+-K+ ATPase inhibitor ouabain (20 μM). This increase in cytosolic [Na+] was a result of activation of a tetrodotoxin-sensitive Na+ influx, but not an inhibition of Na+-K+ ATPase. An increase in cytosolic [Na+] after treating cells with ouabain produced similar effects on Ca2+ regulation as MGO. These results suggest that protein carbonylation can affect cardiac Ca2+ regulation by increasing cytosolic [Na+] via a tetrodotoxin-sensitive pathway. This, in turn, reduces Ca2+ extrusion by NCX, causing SR Ca2+ overload and spontaneous Ca2+ waves.
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Affiliation(s)
- Elisa Bovo
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, 2160 South First Avenue, Maywood, IL, 60153, USA
| | - Jaroslava Seflova
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, 2160 South First Avenue, Maywood, IL, 60153, USA
| | - Seth L Robia
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, 2160 South First Avenue, Maywood, IL, 60153, USA
| | - Aleksey V Zima
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, 2160 South First Avenue, Maywood, IL, 60153, USA.
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3
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Carvajal C, Yan J, Nani A, DeSantiago J, Wan X, Deschenes I, Ai X, Fill M. Isolated Cardiac Ryanodine Receptor Function Varies Between Mammals. J Membr Biol 2024; 257:25-36. [PMID: 38285125 PMCID: PMC11299243 DOI: 10.1007/s00232-023-00301-0] [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: 08/03/2023] [Accepted: 11/24/2023] [Indexed: 01/30/2024]
Abstract
Concerted robust opening of cardiac ryanodine receptors' (RyR2) Ca2+ release 1oplasmic reticulum (SR) is fundamental for normal systolic cardiac function. During diastole, infrequent spontaneous RyR2 openings mediate the SR Ca2+ leak that normally constrains SR Ca2+ load. Abnormal large diastolic RyR2-mediated Ca2+ leak events can cause delayed after depolarizations (DADs) and arrhythmias. The RyR2-associated mechanisms underlying these processes are being extensively studied at multiple levels utilizing various model animals. Since there are well-described species-specific differences in cardiac intracellular Ca2+ handing in situ, we tested whether or not single RyR2 function in vitro retains this species specificity. We isolated RyR2-rich heavy SR microsomes from mouse, rat, rabbit, and human ventricular muscle and quantified RyR2 function using identical solutions and methods. The single RyR2 cytosolic Ca2+ sensitivity was similar across these species. However, there were significant species differences in single RyR2 mean open times in both systole and diastole-like solutions. In diastole-like solutions, single rat/mouse RyR2 open probability and frequency of long openings (> 6 ms) were similar, but these values were significantly greater than those of either single rabbit or human RyR2s. We propose these in vitro single RyR2 functional differences across species stem from the species-specific RyR2 regulatory environment present in the source tissue. Our results show the single rabbit RyR2 functional attributes, particularly in diastole-like conditions, replicate those of single human RyR2 best among the species tested.
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Affiliation(s)
- Catherine Carvajal
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA
| | - Jiajie Yan
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA
- Department of Physiology & Cell Biology, College of Medicine, The Ohio State University, 333 W. 10Th Avenue, Columbus, OH, 43210, USA
| | - Alma Nani
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA
| | - Jaime DeSantiago
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA
| | - Xiaoping Wan
- Department of Physiology & Cell Biology, College of Medicine, The Ohio State University, 333 W. 10Th Avenue, Columbus, OH, 43210, USA
| | - Isabelle Deschenes
- Department of Physiology & Cell Biology, College of Medicine, The Ohio State University, 333 W. 10Th Avenue, Columbus, OH, 43210, USA
| | - Xun Ai
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA.
- Department of Physiology & Cell Biology, College of Medicine, The Ohio State University, 333 W. 10Th Avenue, Columbus, OH, 43210, USA.
| | - Michael Fill
- Department of Physiology & Biophysics, Section of Cellular Signaling, Rush University Medical Center, 1750 W. Harrison Avenue, Chicago, IL, 60612, USA.
- Department of Molecular Biophysics & Physiology, Rush University Medical Center, 1750 West Harrison Street, Columbus, OH, 43210, USA.
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4
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Bovo E, Seflova J, Robia SL, Zima AV. Protein carbonylation causes sarcoplasmic reticulum Ca2+ overload by increasing intracellular Na+ level in ventricular myocytes. RESEARCH SQUARE 2024:rs.3.rs-3991887. [PMID: 38464201 PMCID: PMC10925417 DOI: 10.21203/rs.3.rs-3991887/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Diabetes is commonly associated with an elevated level of reactive carbonyl species due to alteration of glucose and fatty acid metabolism. These metabolic changes cause an abnormality in cardiac Ca2+ regulation that can lead to cardiomyopathies. In this study, we explored how the reactive α-dicarbonyl methylglyoxal (MGO) affects Ca2+ regulation in mouse ventricular myocytes. Analysis of intracellular Ca2+ dynamics revealed that MGO (200 μM) increases action potential (AP)-induced Ca2+ transients and sarcoplasmic reticulum (SR) Ca2+ load, with a limited effect on L-type Ca2+ channel-mediated Ca2+ transients and SERCA-mediated Ca2+ uptake. At the same time, MGO significantly slowed down cytosolic Ca2+ extrusion by Na+/Ca2+ exchanger (NCX). MGO also increased the frequency of Ca2+ waves during rest and these Ca2+ release events were abolished by an external solution with zero [Na+] and [Ca2+]. Adrenergic receptor activation with isoproterenol (10 nM) increased Ca2+ transients and SR Ca2+ load, but it also triggered spontaneous Ca2+ waves in 27% of studied cells. Pretreatment of myocytes with MGO increased the fraction of cells with Ca2+ waves during adrenergic receptor stimulation by 163%. Measurements of intracellular [Na+] revealed that MGO increases cytosolic [Na+] by 57% from the maximal effect produced by the Na+-K+ ATPase inhibitor ouabain (20 μM). This increase in cytosolic [Na+] was a result of activation of a tetrodotoxin-sensitive Na+ influx, but not an inhibition of Na+-K+ ATPase. An increase in cytosolic [Na+] after treating cells with ouabain produced similar effects on Ca2+ regulation as MGO. These results suggest that protein carbonylation can affect cardiac Ca2+ regulation by increasing cytosolic [Na+] via a tetrodotoxin-sensitive pathway. This, in turn, reduces Ca2+ extrusion by NCX, causing SR Ca2+ overload and spontaneous Ca2+ waves.
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Affiliation(s)
- Elisa Bovo
- Loyola University Chicago, Stritch School of Medicine
| | | | - Seth L Robia
- Loyola University Chicago, Stritch School of Medicine
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5
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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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6
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Veron G, Maltsev VA, Stern MD, Maltsev AV. Elementary intracellular Ca signals approximated as a transition of release channel system from a metastable state. JOURNAL OF APPLIED PHYSICS 2023; 134:124701. [PMID: 37744735 PMCID: PMC10517864 DOI: 10.1063/5.0151255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 09/04/2023] [Indexed: 09/26/2023]
Abstract
Cardiac muscle contraction is initiated by an elementary Ca signal (called Ca spark) which is achieved by collective action of Ca release channels in a cluster. The mechanism of this synchronization remains uncertain. We approached Ca spark activation as an emergent phenomenon of an interactive system of release channels. We constructed a weakly lumped Markov chain that applies an Ising model formalism to such release channel clusters and probable open channel configurations and demonstrated that spark activation is described as a system transition from a metastable to an absorbing state, analogous to the pressure required to overcome surface tension in bubble formation. This yielded quantitative estimates of the spark generation probability as a function of various system parameters. We performed numerical simulations to find spark probabilities as a function of sarcoplasmic reticulum Ca concentration, obtaining similar values for spark activation threshold as our analytic model, as well as those reported in experimental studies. Our parametric sensitivity analyses also showed that the spark activation threshold decreased as Ca sensitivity of RyR activation and RyR cluster size increased.
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Affiliation(s)
- Guillermo Veron
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Victor A. Maltsev
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Michael D. Stern
- Cellular Biophysics Section, Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Anna V. Maltsev
- School of Mathematical Sciences, Queen Mary University of London, London E14NS, United Kingdom
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7
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Dorward AM, Stewart AJ, Pitt SJ. The role of Zn2+ in shaping intracellular Ca2+ dynamics in the heart. J Gen Physiol 2023; 155:e202213206. [PMID: 37326614 PMCID: PMC10276528 DOI: 10.1085/jgp.202213206] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 04/18/2023] [Accepted: 05/22/2023] [Indexed: 06/17/2023] Open
Abstract
Increasing evidence suggests that Zn2+ acts as a second messenger capable of transducing extracellular stimuli into intracellular signaling events. The importance of Zn2+ as a signaling molecule in cardiovascular functioning is gaining traction. In the heart, Zn2+ plays important roles in excitation-contraction (EC) coupling, excitation-transcription coupling, and cardiac ventricular morphogenesis. Zn2+ homeostasis in cardiac tissue is tightly regulated through the action of a combination of transporters, buffers, and sensors. Zn2+ mishandling is a common feature of various cardiovascular diseases. However, the precise mechanisms controlling the intracellular distribution of Zn2+ and its variations during normal cardiac function and during pathological conditions are not fully understood. In this review, we consider the major pathways by which the concentration of intracellular Zn2+ is regulated in the heart, the role of Zn2+ in EC coupling, and discuss how Zn2+ dyshomeostasis resulting from altered expression levels and efficacy of Zn2+ regulatory proteins are key drivers in the progression of cardiac dysfunction.
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Affiliation(s)
- Amy M. Dorward
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Alan J. Stewart
- School of Medicine, University of St Andrews, St Andrews, UK
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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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9
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Pick T, Gamayun I, Tinschert R, Cavalié A. Kinetics of the thapsigargin-induced Ca2+ mobilisation: A quantitative analysis in the HEK-293 cell line. Front Physiol 2023; 14:1127545. [PMID: 37051019 PMCID: PMC10083721 DOI: 10.3389/fphys.2023.1127545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/07/2023] [Indexed: 03/29/2023] Open
Abstract
Thapsigargin (TG) inhibits the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) pump and, when applied acutely, it initiates a Ca2+ mobilisation that begins with the loss of Ca2+ from the endoplasmic reticulum (ER) and culminates with store-operated Ca2+ entry (SOCE) from the extracellular space. Using the popular model cell line HEK-293, we quantified TG-induced changes in cytosolic and ER Ca2+ levels using FURA-2 and the FRET-based ER Ca2+ sensor D1ER, respectively. Our analysis predicts an ER Ca2+ leak of 5–6 µM⋅s−1 for the typical basal ER Ca2+ level of 335–407 µM in HEK-293 cells. The resulting cytosolic Ca2+ transients reached peak amplitudes of 0.6–1.0 µM in the absence of external Ca2+ and were amplified by SOCE that amounted to 28–30 nM⋅s−1 in 1 mM external Ca2+. Additionally, cytosolic Ca2+ transients were shaped by a Ca2+ clearance of 10–13 nM⋅s−1. Using puromycin (PURO), which enhances the ER Ca2+ leak, we show that TG-induced cytosolic Ca2+ transients are directly related to ER Ca2+ levels and to the ER Ca2+ leak. A one-compartment model incorporating ER Ca2+ leak and cytosolic Ca2+ clearance accounted satisfactorily for the basic features of TG-induced Ca2+ transients and underpinned the rule that an increase in amplitude associated with shortening of TG-induced cytosolic Ca2+ transients most likely reflects an increase in ER Ca2+ leak.
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Affiliation(s)
- Tillman Pick
- *Correspondence: Tillman Pick, ; Adolfo Cavalié,
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10
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Nikolaienko R, Bovo E, Yuen SL, Treinen LM, Berg K, Aldrich CC, Thomas DD, Cornea RL, Zima AV. New N-aryl-N-alkyl-thiophene-2-carboxamide compound enhances intracellular Ca 2+ dynamics by increasing SERCA2a Ca 2+ pumping. Biophys J 2023; 122:386-396. [PMID: 36463408 PMCID: PMC9892616 DOI: 10.1016/j.bpj.2022.12.002] [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: 07/12/2022] [Revised: 10/31/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
The type 2a sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) plays a central role in the intracellular Ca2+ homeostasis of cardiac myocytes, pumping Ca2+ from the cytoplasm into the sarcoplasmic reticulum (SR) lumen to maintain relaxation (diastole) and prepare for contraction (systole). Diminished SERCA2a function has been reported in several pathological conditions, including heart failure. Therefore, development of new drugs that improve SERCA2a Ca2+ transport is of great clinical significance. In this study, we characterized the effect of a recently identified N-aryl-N-alkyl-thiophene-2-carboxamide (or compound 1) on SERCA2a Ca2+-ATPase and Ca2+ transport activities in cardiac SR vesicles, and on Ca2+ regulation in a HEK293 cell expression system and in mouse ventricular myocytes. We found that compound 1 enhances SERCA2a Ca2+-ATPase and Ca2+ transport in SR vesicles. Fluorescence lifetime measurements of fluorescence resonance energy transfer between SERCA2a and phospholamban indicated that compound 1 interacts with the SERCA-phospholamban complex. Measurement of endoplasmic reticulum Ca2+ dynamics in HEK293 cells expressing human SERCA2a showed that compound 1 increases endoplasmic reticulum Ca2+ load by enhancing SERCA2a-mediated Ca2+ transport. Analysis of cytosolic Ca2+ dynamics in mouse ventricular myocytes revealed that compound 1 increases the action potential-induced Ca2+ transients and SR Ca2+ load, with negligible effects on L-type Ca2+ channels and Na+/Ca2+ exchanger. However, during adrenergic receptor activation, compound 1 did not further increase Ca2+ transients and SR Ca2+ load, but it decreased the propensity toward Ca2+ waves. Suggestive of concurrent desirable effects of compound 1 on RyR2, [3H]-ryanodine binding to cardiac SR vesicles shows a small decrease in nM Ca2+ and a small increase in μM Ca2+. Accordingly, compound 1 slightly decreased Ca2+ sparks in permeabilized myocytes. Thus, this novel compound shows promising characteristics to improve intracellular Ca2+ dynamics in cardiomyocytes that exhibit reduced SERCA2a Ca2+ uptake, as found in failing hearts.
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Affiliation(s)
- Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois
| | - Samantha L Yuen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Levy M Treinen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Kaja Berg
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois.
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11
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Steer EJ, Yang Z, Al-Owais MM, Kirton HM, White E, Steele DS. Flecainide induces a sustained countercurrent dependent effect on RyR2 in permeabilized WT ventricular myocytes but not in intact cells. Front Pharmacol 2023; 14:1155601. [PMID: 37124209 PMCID: PMC10130871 DOI: 10.3389/fphar.2023.1155601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/29/2023] [Indexed: 05/02/2023] Open
Abstract
Background and purpose: While flecainide is now an accepted treatment for arrhythmias associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), its mechanism of action remains controversial. In studies on myocytes from CPVT mice, inhibition of proarrhythmic Ca2+ waves was initially attributed to a novel action on the type-2 ryanodine receptor (RyR2). However, subsequent work on wild type (WT) myocytes questioned the conclusion that flecainide has a direct action on RyR2. In the present study, the effects of flecainide were compared in intact and permeabilized WT myocytes. Experimental approach: Intracellular Ca2+ was measured using confocal microscopy in intact or saponin permeabilized adult rat ventricular myocytes (ARVM). In some experiments on permeabilized cells, flecainide was studied following partial inhibition of the sarcoplasmic reticulum (SR) counter-current. Key results: Flecainide induced sustained changes Ca2+ sparks and waves in permeabilized ARVM, which were comparable to those reported in intact or permeabilized myocytes from CPVT mice. However, a relatively high level of flecainide (25 μM) was required to induce these effects. Inhibition of the SR counter-current potentiated the effects of flecainide on SR Ca2+ waves. In intact field stimulated ARVM, prolonged exposure to 15 μM flecainide decreased wave frequency but RyR2 dependent effects on Ca2+ sparks were absent; higher drug concentrations blocked field stimulation, consistent with inhibition of Nav1.5. Conclusions and implications: In intact ARVM, the absence of effects on Ca2+ sparks suggests that the intracellular flecainide concentration was insufficient to influence RyR2. Wave inhibition in intact ARVM may reflect secondary effects of Nav1.5 inhibition. Potentiation of flecainide's action by counter-current inhibition can be explained if transient polarization of the SR membrane during SR Ca2+ release facilitates its action on RyR2.
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12
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Streiff ME, Corbin AC, Ahmad AA, Hunter C, Sachse FB. TRPC1 channels underlie stretch-modulated sarcoplasmic reticulum calcium leak in cardiomyocytes. Front Physiol 2022; 13:1056657. [PMID: 36620209 PMCID: PMC9817106 DOI: 10.3389/fphys.2022.1056657] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 12/12/2022] [Indexed: 12/25/2022] Open
Abstract
Transient receptor potential canonical 1 (TRPC1) channels are Ca2+-permeable ion channels expressed in cardiomyocytes. An involvement of TRPC1 channels in cardiac diseases is widely established. However, the physiological role of TRPC1 channels and the mechanisms through which they contribute to disease development are still under investigation. Our prior work suggested that TRPC1 forms Ca2+ leak channels located in the sarcoplasmic reticulum (SR) membrane. Prior studies suggested that TRPC1 channels in the cell membrane are mechanosensitive, but this was not yet investigated in cardiomyocytes or for SR localized TRPC1 channels. We applied adenoviral transfection to overexpress or suppress TRPC1 expression in neonatal rat ventricular myocytes (NRVMs). Transfections were evaluated with RT-qPCR, western blot, and fluorescent imaging. Single-molecule localization microscopy revealed high colocalization of exogenously expressed TRPC1 and the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2). To test our hypothesis that TRPC1 channels contribute to mechanosensitive Ca2+ SR leak, we directly measured SR Ca2+ concentration ([Ca2+]SR) using adenoviral transfection with a novel ratiometric genetically encoded SR-targeting Ca2+ sensor. We performed fluorescence imaging to quantitatively assess [Ca2+]SR and leak through TRPC1 channels of NRVMs cultured on stretchable silicone membranes. [Ca2+]SR was increased in cells with suppressed TRPC1 expression vs. control and Transient receptor potential canonical 1-overexpressing cells. We also detected a significant reduction in [Ca2+]SR in cells with Transient receptor potential canonical 1 overexpression when 10% uniaxial stretch was applied. These findings indicate that TRPC1 channels underlie the mechanosensitive modulation of [Ca2+]SR. Our findings are critical for understanding the physiological role of TRPC1 channels and support the development of pharmacological therapies for cardiac diseases.
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Affiliation(s)
- Molly E. Streiff
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Andrea C. Corbin
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Azmi A. Ahmad
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Chris Hunter
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
| | - Frank B. Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
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13
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Demydenko K, Ekhteraei-Tousi S, Roderick HL. Inositol 1,4,5-trisphosphate receptors in cardiomyocyte physiology and disease. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210319. [PMID: 36189803 PMCID: PMC9527928 DOI: 10.1098/rstb.2021.0319] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contraction of cardiac muscle underlying the pumping action of the heart is mediated by the process of excitation-contraction coupling (ECC). While triggered by Ca2+ entry across the sarcolemma during the action potential, it is the release of Ca2+ from the sarcoplasmic reticulum (SR) intracellular Ca2+ store via ryanodine receptors (RyRs) that plays the major role in induction of contraction. Ca2+ also acts as a key intracellular messenger regulating transcription underlying hypertrophic growth. Although Ca2+ release via RyRs is by far the greatest contributor to the generation of Ca2+ transients in the cardiomyocyte, Ca2+ is also released from the SR via inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs). This InsP3-induced Ca2+ release modifies Ca2+ transients during ECC, participates in directing Ca2+ to the mitochondria, and stimulates the transcription of genes underlying hypertrophic growth. Central to these specific actions of InsP3Rs is their localization to responsible signalling microdomains, the dyad, the SR-mitochondrial interface and the nucleus. In this review, the various roles of InsP3R in cardiac (patho)physiology and the mechanisms by which InsP3 signalling selectively influences the different cardiomyocyte cell processes in which it is involved will be presented. 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)
- Kateryna Demydenko
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Samaneh Ekhteraei-Tousi
- 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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14
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Jin X, Amoni M, Gilbert G, Dries E, Doñate Puertas R, Tomar A, Nagaraju CK, Pradhan A, Yule DI, Martens T, Menten R, Vanden Berghe P, Rega F, Sipido K, Roderick HL. InsP 3R-RyR Ca 2+ channel crosstalk facilitates arrhythmias in the failing human ventricle. Basic Res Cardiol 2022; 117:60. [PMID: 36378362 DOI: 10.1007/s00395-022-00967-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/13/2022] [Accepted: 10/31/2022] [Indexed: 11/16/2022]
Abstract
Dysregulated intracellular Ca2+ handling involving altered Ca2+ release from intracellular stores via RyR channels underlies both arrhythmias and reduced function in heart failure (HF). Mechanisms linking RyR dysregulation and disease are not fully established. Studies in animals support a role for InsP3 receptor Ca2+ channels (InsP3R) in pathological alterations in cardiomyocyte Ca2+ handling but whether these findings translate to the divergent physiology of human cardiomyocytes during heart failure is not determined. Using electrophysiological and Ca2+ recordings in human ventricular cardiomyocytes, we uncovered that Ca2+ release via InsP3Rs facilitated Ca2+ release from RyR and induced arrhythmogenic delayed after depolarisations and action potentials. InsP3R-RyR crosstalk was particularly increased in HF at RyR clusters isolated from the T-tubular network. Reduced SERCA activity in HF further facilitated the action of InsP3. Nanoscale imaging revealed co-localisation of InsP3Rs with RyRs in the dyad, which was increased in HF, providing a mechanism for augmented Ca2+ channel crosstalk. Notably, arrhythmogenic activity dependent on InsP3Rs was increased in tissue wedges from failing hearts perfused with AngII to promote InsP3 generation. These data indicate a central role for InsP3R-RyR Ca2+ signalling crosstalk in the pro-arrhythmic action of GPCR agonists elevated in HF and the potential for their therapeutic targeting.
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Affiliation(s)
- Xin Jin
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium.,Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Matthew Amoni
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Guillaume Gilbert
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Eef Dries
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Rosa Doñate Puertas
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Ashutosh Tomar
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Chandan K Nagaraju
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Ankit Pradhan
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - David I Yule
- Department of Pharmacology and Physiology, Medical Center School of Medicine and Dentistry, University of Rochester, 601 Elmwood Avenue, Box 711, Rochester, NY, 14642, USA
| | - Tobie Martens
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, 3000, Leuven, Belgium.,Cell and Tissue Imaging Cluster (CIC), KU Leuven, 3000, Leuven, Belgium
| | - Roxane Menten
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - Pieter Vanden Berghe
- Laboratory for Enteric NeuroScience (LENS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven, 3000, Leuven, Belgium.,Cell and Tissue Imaging Cluster (CIC), KU Leuven, 3000, Leuven, Belgium
| | - Filip Rega
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium.,Department of Cardiology and Department of Cardiac Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Karin Sipido
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium
| | - H Llewelyn Roderick
- Department of Cardiovascular Sciences, Laboratory of Experimental Cardiology, KU Leuven, 3000, Leuven, Belgium.
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15
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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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16
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Fu ZP, Wu LL, Xue JY, Zhang LE, Li C, You HJ, Luo DL. Connexin 43 hyper-phosphorylation at serine 282 triggers apoptosis in rat cardiomyocytes via activation of mitochondrial apoptotic pathway. Acta Pharmacol Sin 2022; 43:1970-1978. [PMID: 34931018 PMCID: PMC9343349 DOI: 10.1038/s41401-021-00824-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/16/2021] [Indexed: 12/12/2022] Open
Abstract
Cx43 is the major connexin in ventricular gap junctions, and plays a pivotal role in control of electrical and metabolic communication among adjacent cardiomyocytes. We previously found that Cx43 dephosphorylation at serine 282 (pS282) caused cardiomyocyte apoptosis, which is involved in cardiac ischemia/reperfusion injury. In this study we investigated whether Cx43-S282 hyper-phosphorylation could protect cardiomyocytes against apoptosis. Adenovirus carrying rat full length Cx43 gene (Cx43-wt) or a mutant gene at S282 substituted with aspartic acid (S282D) were transfected into neonatal rat ventricular myocytes (NRVMs) or injected into rat ventricular wall. Rat abdominal aorta constriction model (AAC) was used to assess Cx43-S282 phosphorylation status. We showed that Cx43 phosphorylation at S282 was increased over 2-times compared to Cx43-wt cells at 24 h after transfection, while pS262 and pS368 were unaltered. S282D-transfected cells displayed enhanced gap junctional communication, and increased basal intracellular Ca2+ concentration and spontaneous Ca2+ transients compared to Cx43-wt cells. However, spontaneous apoptosis appeared in NRVMs transfected with S282D for 34 h. Rat ventricular myocardium transfected with S282D in vivo also exhibited apoptotic responses, including increased Bax/Bcl-xL ratio, cytochrome c release as well as caspase-3 and caspase-9 activities, while factor-associated suicide (Fas)/Fas-associated death domain expression and caspase-8 activity remained unaltered. In addition, AAC-induced hypertrophic ventricles had apoptotic injury with Cx43-S282 hyper-phosphorylation compared with Sham ventricles. In conclusion, Cx43 hyper-phosphorylation at S282, as dephosphorylation, also triggers cardiomyocyte apoptosis, but through activation of mitochondrial apoptosis pathway, providing a fine-tuned Cx43-S282 phosphorylation range required for the maintenance of cardiomyocyte function and survival.
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Affiliation(s)
- Zhi-ping Fu
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Lu-lin Wu
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Jing-yi Xue
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Lan-e Zhang
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Chen Li
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Hong-jie You
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
| | - Da-li Luo
- grid.24696.3f0000 0004 0369 153XDepartment of Pharmacology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Capital Medical University, Beijing, 100069 China
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17
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Molecular, Subcellular, and Arrhythmogenic Mechanisms in Genetic RyR2 Disease. Biomolecules 2022; 12:biom12081030. [PMID: 35892340 PMCID: PMC9394283 DOI: 10.3390/biom12081030] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/22/2022] [Accepted: 07/24/2022] [Indexed: 11/17/2022] Open
Abstract
The ryanodine receptor (RyR2) has a critical role in controlling Ca2+ release from the sarcoplasmic reticulum (SR) throughout the cardiac cycle. RyR2 protein has multiple functional domains with specific roles, and four of these RyR2 protomers are required to form the quaternary structure that comprises the functional channel. Numerous mutations in the gene encoding RyR2 protein have been identified and many are linked to a wide spectrum of arrhythmic heart disease. Gain of function mutations (GoF) result in a hyperactive channel that causes excessive spontaneous SR Ca2+ release. This is the predominant cause of the inherited syndrome catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, rare hypoactive loss of function (LoF) mutations have been identified that produce atypical effects on cardiac Ca2+ handling that has been termed calcium release deficiency syndrome (CRDS). Aberrant Ca2+ release resulting from both GoF and LoF mutations can result in arrhythmias through the Na+/Ca2+ exchange mechanism. This mini-review discusses recent findings regarding the role of RyR2 domains and endogenous regulators that influence RyR2 gating normally and with GoF/LoF mutations. The arrhythmogenic consequences of GoF/LoF mutations will then be discussed at the macromolecular and cellular level.
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18
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Streiff ME, Sachse FB. Effects of Sarcolemmal Background Ca2+ Entry and Sarcoplasmic Ca2+ Leak Currents on Electrophysiology and Ca2+ Transients in Human Ventricular Cardiomyocytes: A Computational Comparison. Front Physiol 2022; 13:916278. [PMID: 35784869 PMCID: PMC9243544 DOI: 10.3389/fphys.2022.916278] [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: 04/09/2022] [Accepted: 05/27/2022] [Indexed: 11/30/2022] Open
Abstract
The intricate regulation of the compartmental Ca2+ concentrations in cardiomyocytes is critical for electrophysiology, excitation-contraction coupling, and other signaling pathways. Research into the complex signaling pathways is motivated by cardiac pathologies including arrhythmia and maladaptive myocyte remodeling, which result from Ca2+ dysregulation. Of interest to this investigation are two types of Ca2+ currents in cardiomyocytes: 1) background Ca2+ entry, i.e., Ca2+ transport across the sarcolemma from the extracellular space into the cytosol, and 2) Ca2+ leak from the sarcoplasmic reticulum (SR) across the SR membrane into the cytosol. Candidates for the ion channels underlying background Ca2+ entry and SR Ca2+ leak channels include members of the mechano-modulated transient receptor potential (TRP) family. We used a mathematical model of a human ventricular myocyte to analyze the individual contributions of background Ca2+ entry and SR Ca2+ leak to the modulation of Ca2+ transients and SR Ca2+ load at rest and during action potentials. Background Ca2+ entry exhibited a positive relationship with both [Ca2+]i and [Ca2+]SR. Modulating SR Ca2+ leak had opposite effects of background Ca2+ entry. Effects of SR Ca2+ leak on Ca2+ were particularly pronounced at lower pacing frequency. In contrast to the pronounced effects of background and leak Ca2+ currents on Ca2+ concentrations, the effects on cellular electrophysiology were marginal. Our studies provide quantitative insights into the differential modulation of compartmental Ca2+ concentrations by the background and leak Ca2+ currents. Furthermore, our studies support the hypothesis that TRP channels play a role in strain-modulation of cardiac contractility. In summary, our investigations shed light on the physiological effects of the background and leak Ca2+ currents and their contribution to the development of disease caused by Ca2+ dysregulation.
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Affiliation(s)
- Molly E. Streiff
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Frank B. Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- *Correspondence: Frank B. Sachse,
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19
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Zhang XY, Wang DH. Gut Microbial Community and Host Thermoregulation in Small Mammals. Front Physiol 2022; 13:888324. [PMID: 35480035 PMCID: PMC9035535 DOI: 10.3389/fphys.2022.888324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 03/28/2022] [Indexed: 11/13/2022] Open
Abstract
The endotherms, particularly the small mammals living in the polar region and temperate zone, are faced with extreme challenges for maintaining stable core body temperatures in harsh cold winter. The non-hibernating small mammals increase metabolic rate including obligatory thermogenesis (basal/resting metabolic rate, BMR/RMR) and regulatory thermogenesis (mainly nonshivering thermogenesis, NST, in brown adipose tissue and skeletal muscle) to maintain thermal homeostasis in cold conditions. A substantial amount of evidence indicates that the symbiotic gut microbiota are sensitive to air temperature, and play an important function in cold-induced thermoregulation, via bacterial metabolites and byproducts such as short-chain fatty acids and secondary bile acids. Cold signal is sensed by specific thermosensitive transient receptor potential channels (thermo-TRPs), and then norepinephrine (NE) is released from sympathetic nervous system (SNS) and thyroid hormones also increase to induce NST. Meanwhile, these neurotransmitters and hormones can regulate the diversity and compositions of the gut microbiota. Therefore, cold-induced NST is controlled by both Thermo-TRPs—SNS—gut microbiota axis and thyroid—gut microbiota axis. Besides physiological thermoregulation, small mammals also rely on behavioral regulation, such as huddling and coprophagy, to maintain energy and thermal homeostasis, and the gut microbial community is involved in these processes. The present review summarized the recent progress in the gut microbiota and host physiological and behavioral thermoregulation in small mammals for better understanding the evolution and adaption of holobionts (host and symbiotic microorganism). The coevolution of host-microorganism symbionts promotes individual survival, population maintenance, and species coexistence in the ecosystems with complicated, variable environments.
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Affiliation(s)
- Xue-Ying Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - De-Hua Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Shandong University, Qingdao, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: De-Hua Wang,
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20
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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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21
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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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22
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Estimating ectopic beat probability with simplified statistical models that account for experimental uncertainty. PLoS Comput Biol 2021; 17:e1009536. [PMID: 34665814 PMCID: PMC8577785 DOI: 10.1371/journal.pcbi.1009536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 11/09/2021] [Accepted: 10/06/2021] [Indexed: 11/21/2022] Open
Abstract
Ectopic beats (EBs) are cellular arrhythmias that can trigger lethal arrhythmias. Simulations using biophysically-detailed cardiac myocyte models can reveal how model parameters influence the probability of these cellular arrhythmias, however such analyses can pose a huge computational burden. Here, we develop a simplified approach in which logistic regression models (LRMs) are used to define a mapping between the parameters of complex cell models and the probability of EBs (P(EB)). As an example, in this study, we build an LRM for P(EB) as a function of the initial value of diastolic cytosolic Ca2+ concentration ([Ca2+]iini), the initial state of sarcoplasmic reticulum (SR) Ca2+ load ([Ca2+]SRini), and kinetic parameters of the inward rectifier K+ current (IK1) and ryanodine receptor (RyR). This approach, which we refer to as arrhythmia sensitivity analysis, allows for evaluation of the relationship between these arrhythmic event probabilities and their associated parameters. This LRM is also used to demonstrate how uncertainties in experimentally measured values determine the uncertainty in P(EB). In a study of the role of [Ca2+]SRini uncertainty, we show a special property of the uncertainty in P(EB), where with increasing [Ca2+]SRini uncertainty, P(EB) uncertainty first increases and then decreases. Lastly, we demonstrate that IK1 suppression, at the level that occurs in heart failure myocytes, increases P(EB). An ectopic beat is an abnormal cellular electrical event which can trigger dangerous arrhythmias in the heart. Complex biophysical models of the cardiac myocyte can be used to reveal how cell properties affect the probability of ectopic beats. However, such analyses can pose a huge computational burden. We develop a simplified approach that enables a highly complex biophysical model to be reduced to a rather simple statistical model from which the functional relationship between myocyte model parameters and the probability of an ectopic beat is determined. We refer to this approach as arrhythmia sensitivity analysis. Given the efficiency of our approach, we also use it to demonstrate how uncertainties in experimentally measured myocyte model parameters determine the uncertainty in ectopic beat probability. We find that, with increasing model parameter uncertainty, the uncertainty in probability of ectopic beat first increases and then decreases. In general, our approach can efficiently analyze the relationship between cardiac myocyte parameters and the probability of ectopic beats and can be used to study how uncertainty of these cardiac myocyte parameters influences the ectopic beat probability.
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23
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Baier MJ, Noack J, Seitz MT, Maier LS, Neef S. Phosphorylation of RyR2 Ser-2814 by CaMKII mediates β1-adrenergic stress induced Ca 2+ -leak from the sarcoplasmic reticulum. FEBS Open Bio 2021; 11:2756-2762. [PMID: 34403217 PMCID: PMC8487045 DOI: 10.1002/2211-5463.13274] [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: 04/15/2021] [Revised: 08/03/2021] [Accepted: 08/16/2021] [Indexed: 11/26/2022] Open
Abstract
Adrenergic stimulation, while being the central mechanism of cardiac positive inotropy, is a universally acknowledged inductor of undesirable sarcoplasmic reticulum (SR) Ca2+ leak. However, the exact mechanisms for this remained unspecified so far. This study shows that Ca2+/calmodulin‐dependent protein kinase II (CaMKII)‐specific phosphorylation of ryanodine receptor type 2 at Ser‐2814 is the pivotal mechanism by which SR Ca2+ leak develops downstream of β1‐adrenergic stress by increase of the leak/load relationship. Cardiomyocytes with a Ser‐2814 phosphoresistant mutation (S2814A) were protected from isoproterenol‐induced SR Ca2+ leak and consequently displayed improved postrest potentiation of systolic Ca2+ release under adrenergic stress compared to littermate wild‐type cells.
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Affiliation(s)
- Maria J Baier
- Department of Internal Medicine II, University Medical Center Regensburg, Germany
| | - Jannis Noack
- Department of Internal Medicine II, University Medical Center Regensburg, Germany
| | - Mark Tilmann Seitz
- Department of Trauma Surgery, Orthopaedics and Plastic Surgery, University Medical Center Göttingen, Germany
| | - Lars S Maier
- Department of Internal Medicine II, University Medical Center Regensburg, Germany
| | - Stefan Neef
- Department of Internal Medicine II, University Medical Center Regensburg, Germany
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24
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Val‐Blasco A, Gil‐Fernández M, Rueda A, Pereira L, Delgado C, Smani T, Ruiz Hurtado G, Fernández‐Velasco M. Ca 2+ mishandling in heart failure: Potential targets. Acta Physiol (Oxf) 2021; 232:e13691. [PMID: 34022101 DOI: 10.1111/apha.13691] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 05/17/2021] [Accepted: 05/19/2021] [Indexed: 12/14/2022]
Abstract
Ca2+ mishandling is a common feature in several cardiovascular diseases such as heart failure (HF). In many cases, impairment of key players in intracellular Ca2+ homeostasis has been identified as the underlying mechanism of cardiac dysfunction and cardiac arrhythmias associated with HF. In this review, we summarize primary novel findings related to Ca2+ mishandling in HF progression. HF research has increasingly focused on the identification of new targets and the contribution of their role in Ca2+ handling to the progression of the disease. Recent research studies have identified potential targets in three major emerging areas implicated in regulation of Ca2+ handling: the innate immune system, bone metabolism factors and post-translational modification of key proteins involved in regulation of Ca2+ handling. Here, we describe their possible contributions to the progression of HF.
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Affiliation(s)
| | | | - Angélica Rueda
- Department of Biochemistry Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV‐IPN) México City Mexico
| | - Laetitia Pereira
- INSERM UMR‐S 1180 Laboratory of Ca Signaling and Cardiovascular Physiopathology University Paris‐Saclay Châtenay‐Malabry France
| | - Carmen Delgado
- Instituto de Investigaciones Biomédicas Alberto Sols Madrid Spain
- Department of Metabolism and Cell Signalling Biomedical Research Institute "Alberto Sols" CSIC‐UAM Madrid Spain
| | - Tarik Smani
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV) Madrid Spain
- Department of Medical Physiology and Biophysics University of Seville Seville Spain
- Group of Cardiovascular Pathophysiology Institute of Biomedicine of Seville University Hospital of Virgen del Rocío, University of Seville, CSIC Seville Spain
| | - Gema Ruiz Hurtado
- Cardiorenal Translational Laboratory Institute of Research i+12 University Hospital 12 de Octubre Madrid Spain
- CIBER‐CV University Hospita1 12 de Octubre Madrid Spain
| | - Maria Fernández‐Velasco
- La Paz University Hospital Health Research Institute IdiPAZ Madrid Spain
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV) Madrid Spain
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25
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Sato D, Uchinoumi H, Bers DM. Increasing SERCA function promotes initiation of calcium sparks and breakup of calcium waves. J Physiol 2021; 599:3267-3278. [PMID: 33963531 PMCID: PMC8249358 DOI: 10.1113/jp281579] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/04/2021] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Increasing sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pump activity enhances sarcoplasmic reticulum calcium (Ca) load, which increases both ryanodine receptor opening and driving force of Ca release flux. Both of these effects promote Ca spark formation and wave propagation. However, increasing SERCA activity also accelerates local cytosolic Ca decay as the wave front travels to the next cluster, which limits wave propagation. As a result, increasing SERCA pump activity has a biphasic effect on the propensity of arrhythmogenic Ca waves, but a monotonic effect to increase Ca spark frequency and amplitude. ABSTRACT Waves of sarcoplasmic reticulum (SR) calcium (Ca) release can cause arrhythmogenic afterdepolarizations in cardiac myocytes. Ca waves propagate when Ca sparks at one Ca release unit (CRU) recruit new Ca sparks in neighbouring CRUs. Under normal conditions, Ca sparks are too small to recruit neighbouring Ca sparks where Ca sensitivity is also low. However, under pathological conditions such as a Ca overload or ryanodine receptor (RyR) sensitization, Ca sparks can be larger and propagate more readily as macro-sparks or full Ca waves. Increasing SERCA pump activity promotes SR Ca load, which promotes RyR opening and increases driving force of the Ca release flux from SR to cytosol, promoting Ca waves. However, high sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) activity can also decrease local cytosolic [Ca] as it approaches the next CRU, thereby reducing wave appearance and propagation. In this study, we use a physiologically detailed model of subcellular Ca cycling and experiments in phospholamban-knockout mice, to show how Ca waves are initiated and propagate and how different conditions contribute to the generation and propagation of Ca waves. We show that reducing diffusive coupling between Ca sparks by increasing SERCA activity prevents Ca waves by reducing [Ca] at the next CRU, as do Ca buffers, low intra-SR Ca diffusion and distance between CRUs. Increasing SR Ca uptake rate has a biphasic effect on Ca wave propagation; initially it enhances Ca spark probability and amplitude and CRU coupling, thereby promoting arrhythmogenic Ca wave propagation, but at higher levels SR Ca uptake can abort those arrhythmogenic Ca waves.
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Affiliation(s)
- Daisuke Sato
- Department of Pharmacology, University of California, Davis School of Medicine, California, USA
| | - Hitoshi Uchinoumi
- Department of Pharmacology, University of California, Davis School of Medicine, California, USA.,Department of Cardiology, Yamaguchi University School of Medicine, Yamaguchi, Japan
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis School of Medicine, California, USA
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26
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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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27
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Fill M, Gillespie D. Simulating cardiac Ca 2+ release units: effects of RyR cluster size and Ca 2+ buffers on diastolic Ca 2+ leak. Pflugers Arch 2021; 473:435-446. [PMID: 33608799 DOI: 10.1007/s00424-021-02539-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/27/2021] [Accepted: 02/05/2021] [Indexed: 10/22/2022]
Abstract
Leak of Ca2+ out of the cardiac sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) during diastole is vital to regulate SR Ca2+ levels. This leak can become deleterious when large spontaneous RyR-mediated Ca2+ release events evoke proarrhythmic Ca2+ waves that can lead to delayed after-depolarizations. Here, we model diastolic SR Ca2+ leak at individual SR Ca2+ release sites using computer simulations of RyR arrays like those in the dyadic cleft. The results show that RyR arrays size has a significant effect on SR Ca2+ leak, with bigger arrays producing larger and more frequent Ca2+ release events. Moreover, big RyR arrays are more susceptible to small changes in the levels of dyadic Ca2+ buffers. Such changes in buffering shift Ca2+ leak from small Ca2+ release events (involving few open RyRs) to larger events (with many open RyRs). Moreover, by analyzing a large parameter space of possible buffering and SR Ca2+ loads, we find further evidence for the hypothesis that SR Ca2+ leak by RyR arrays can undergo a sudden phase transition.
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Affiliation(s)
- Michael Fill
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA
| | - Dirk Gillespie
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, USA.
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28
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Zhang XH, Wei H, Xia Y, Morad M. Calcium signaling consequences of RyR2 mutations associated with CPVT1 introduced via CRISPR/Cas9 gene editing in human-induced pluripotent stem cell-derived cardiomyocytes: Comparison of RyR2-R420Q, F2483I, and Q4201R. Heart Rhythm 2021; 18:250-260. [PMID: 32931925 PMCID: PMC7893824 DOI: 10.1016/j.hrthm.2020.09.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) created from patients with catecholaminergic polymorphic ventricular tachycardia 1 (CPVT1) have been used to study CPVT1 arrhythmia. OBJECTIVE The purpose of this study was to evaluate the Ca2+ signaling aberrancies and pharmacological sensitivities of 3 CRISPR/Cas9-introduced CPVT1 mutations located in different molecular domains of ryanodine receptor 2 (RyR2). METHODS CRISPR/Cas9-engineered hiPSC-CMs carrying RyR2 mutations-R420Q, Q4201R, and F2483I-were voltage clamped, and their electrophysiology, pharmacology, and Ca2+ signaling phenotypes measured using total internal reflection fluorescence microscopy. RESULTS R420Q and Q4201R mutant hiPSC-CMs exhibit irregular, long-lasting, spatially wandering Ca2+ sparks and aberrant Ca2+ releases similar to F2483I unlike the wild-type myocytes. Large sarcoplasmic reticulum (SR) Ca2+ leaks and smaller SR Ca2+ contents were detected in cells expressing Q4201R and F2483I, but not R420Q. Fractional Ca2+ release and calcium-induced calcium release gain were higher in Q4201R than in R420Q and F2483I hiPSC-CMs. JTV519 was equally effective in suppressing Ca2+ sparks, waves, and SR Ca2+ leaks in hiPSC-CMs derived from all 3 mutant lines. Flecainide and dantrolene similarly suppressed SR Ca2+ leaks, but were less effective in decreasing spark frequency and durations. CONCLUSION CRISPR/Cas9 gene editing of hiPSCs provides a novel approach in studying CPVT1-associated RyR2 mutations and suggests that Ca2+-signaling aberrancies and drug sensitivities may vary depending on the mutation site.
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Affiliation(s)
- Xiao-Hua Zhang
- Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Hua Wei
- Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Yanli Xia
- Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Martin Morad
- Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina.
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29
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Blatter LA, Kanaporis G, Martinez-Hernandez E, Oropeza-Almazan Y, Banach K. Excitation-contraction coupling and calcium release in atrial muscle. Pflugers Arch 2021; 473:317-329. [PMID: 33398498 DOI: 10.1007/s00424-020-02506-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/03/2020] [Accepted: 12/16/2020] [Indexed: 01/02/2023]
Abstract
In cardiac muscle, the process of excitation-contraction coupling (ECC) describes the chain of events that links action potential induced myocyte membrane depolarization, surface membrane ion channel activation, triggering of Ca2+ induced Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store to activation of the contractile machinery that is ultimately responsible for the pump function of the heart. Here we review similarities and differences of structural and functional attributes of ECC between atrial and ventricular tissue. We explore a novel "fire-diffuse-uptake-fire" paradigm of atrial ECC and Ca2+ release that assigns a novel role to the SR SERCA pump and involves a concerted "tandem" activation of the ryanodine receptor Ca2+ release channel by cytosolic and luminal Ca2+. We discuss the contribution of the inositol 1,4,5-trisphosphate (IP3) receptor Ca2+ release channel as an auxiliary pathway to Ca2+ signaling, and we review IP3 receptor-induced Ca2+ release involvement in beat-to-beat ECC, nuclear Ca2+ signaling, and arrhythmogenesis. Finally, we explore the topic of electromechanical and Ca2+ alternans and its ramifications for atrial arrhythmia.
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Affiliation(s)
- L A Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA.
| | - G Kanaporis
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - E Martinez-Hernandez
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - Y Oropeza-Almazan
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - K Banach
- Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL, 60612, USA
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30
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Nikolaienko R, Bovo E, Rebbeck RT, Kahn D, Thomas DD, Cornea RL, Zima AV. The functional significance of redox-mediated intersubunit cross-linking in regulation of human type 2 ryanodine receptor. Redox Biol 2020; 37:101729. [PMID: 32980662 PMCID: PMC7522892 DOI: 10.1016/j.redox.2020.101729] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/19/2020] [Accepted: 09/11/2020] [Indexed: 02/07/2023] Open
Abstract
The type 2 ryanodine receptor (RyR2) plays a key role in the cardiac intracellular calcium (Ca2+) regulation. We have previously shown that oxidative stress activates RyR2 in rabbit cardiomyocytes by promoting the formation of disulfide bonds between neighboring RyR2 subunits. However, the functional significance of this redox modification for human RyR2 (hRyR2) remains largely unknown. Here, we studied the redox regulation of hRyR2 in HEK293 cells transiently expressing the ryr2 gene. Analysis of hRyR2 cross-linking and of the redox-GFP readout response to diamide oxidation revealed that hRyR2 cysteines involved in the intersubunit cross-linking are highly sensitive to oxidative stress. In parallel experiments, the effect of diamide on endoplasmic reticulum (ER) Ca2+ release was studied in cells co-transfected with hRyR2, ER Ca2+ pump (SERCA2a) and the ER-targeted Ca2+ sensor R-CEPIA1er. Expression of hRyR2 and SERCA2a produced “cardiac-like” Ca2+ waves due to spontaneous hRyR2 activation. Incubation with diamide caused a fast decline of the luminal ER Ca2+ (or ER Ca2+ load) followed by the cessation of Ca2+ waves. The maximal effect of diamide on ER Ca2+ load and Ca2+ waves positively correlates with the maximum level of hRyR2 cross-linking, indicating a functional significance of this redox modification. Furthermore, the level of hRyR2 cross-linking positively correlates with the degree of calmodulin (CaM) dissociation from the hRyR2 complex. In skeletal muscle RyR (RyR1), cysteine 3635 (C3635) is viewed as dominantly responsible for the redox regulation of the channel. Here, we showed that the corresponding cysteine 3602 (C3602) in hRyR2 does not participate in intersubunit cross-linking and plays a limited role in the hRyR2 regulation by CaM during oxidative stress. Collectively, these results suggest that redox-mediated intersubunit cross-linking is an important regulator of hRyR2 function under pathological conditions associated with oxidative stress. Oxidative stress promotes cardiac ryanodine receptor (RyR2) intersubunit crosslinking. Human RyR2 crosslinking promotes Ca leak and calmodulin dissociation. RyR2 C3602 is not involved in crosslinking, slightly affects calmodulin binding. RyR2 crosslinking is an important pathology related RyR2 regulator.
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Affiliation(s)
- Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Daniel Kahn
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA.
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31
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Firth JM, Yang HY, Francis AJ, Islam N, MacLeod KT. The Effect of Estrogen on Intracellular Ca 2+ and Na + Regulation in Heart Failure. ACTA ACUST UNITED AC 2020; 5:901-912. [PMID: 33015413 PMCID: PMC7524784 DOI: 10.1016/j.jacbts.2020.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 12/31/2022]
Abstract
During the progression toward heart failure, indicators of in vivo whole-heart function suggest greater impairment in the absence of estrogen. At the single cardiac myocyte level, the absence of estrogen results in further reduction of Ca2+ transient amplitudes, further slowing of transient decay kinetics, less SR Ca2+ content, and a further increase in Ca2+ spark frequencies and spark-mediated SR leak compared with animals with normal estrus cycles. Cardiac myocyte Na+ regulation is also more disrupted in the absence of estrogen.
Contradictory findings of estrogen supplementation in cardiac disease highlight the need to investigate the involvement of estrogen in the progression of heart failure in an animal model that lacks traditional comorbidities. Heart failure was induced by aortic constriction (AC) in female guinea pigs. Selected AC animals were ovariectomized (ACOV), and a group of these received 17β-estradiol supplementation (ACOV+E). One hundred-fifty days post-AC surgery, left-ventricular myocytes were isolated, and their electrophysiology and Ca2+ and Na+ regulation were examined. Long-term absence of ovarian hormones exacerbates the decline in cardiac function during the progression to heart failure. Estrogen supplementation reverses these aggravating effects.
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Key Words
- AC, aortic constriction
- ACOV+E, aortic constriction with ovariectomy, supplemented with 17β-estradiol
- ACOV, aortic constriction with ovariectomy
- FS, fractional shortening
- ICa, l-type Ca2+ channel current (cadmium-sensitive)
- INa,L, late Na+ current (ranolazine-sensitive)
- NCX, Na+/Ca2+ exchange
- OV, ovariectomy
- SERCA, Sarco/endoplasmic reticulum Ca2+-ATPase
- SR, sarcoplasmic reticulum
- calcium regulation
- cardiomyocytes
- estrogen
- excitation-contraction coupling
- female
- heart failure
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Affiliation(s)
- Jahn M Firth
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital, London, United Kingdom
| | - Hsiang-Yu Yang
- Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (R.O.C.)
| | - Alice J Francis
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital, London, United Kingdom
| | - Najah Islam
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital, London, United Kingdom
| | - Kenneth T MacLeod
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital, London, United Kingdom
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32
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Dimerization of SERCA2a Enhances Transport Rate and Improves Energetic Efficiency in Living Cells. Biophys J 2020; 119:1456-1465. [PMID: 32946770 DOI: 10.1016/j.bpj.2020.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/07/2020] [Accepted: 08/25/2020] [Indexed: 11/21/2022] Open
Abstract
The type 2a sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA2a) plays a key role in intracellular Ca2+ regulation in the heart. We have previously shown evidence of stable homodimers of SERCA2a in heterologous cells and cardiomyocytes. However, the functional significance of the pump dimerization remains unclear. Here, we analyzed how SERCA2a dimerization affects ER Ca2+ transport. Fluorescence resonance energy transfer experiments in HEK293 cells transfected with fluorescently labeled SERCA2a revealed increasing dimerization of Ca2+ pumps with increasing expression level. This concentration-dependent dimerization provided means of comparison of the functional characteristics of monomeric and dimeric pumps. SERCA-mediated Ca2+ uptake was measured with the ER-targeted Ca2+ sensor R-CEPIA1er in cells cotransfected with SERCA2a and ryanodine receptor. For each individual cell, the maximal ER Ca2+ uptake rate and the maximal Ca2+ load, together with the pump expression level, were analyzed. This analysis revealed that the ER Ca2+ uptake rate increased as a function of SERCA2a expression, with a particularly steep, nonlinear increase at high expression levels. Interestingly, the maximal ER Ca2+ load also increased with an increase in the pump expression level, suggesting improved catalytic efficiency of the dimeric species. Reciprocally, thapsigargin inhibition of a fraction of the population of SERCA2a reduced not only the maximal ER Ca2+ uptake rate but also the maximal Ca2+ load. These data suggest that SERCA2a dimerization regulates Ca2+ transport by improving both the SERCA2a turnover rate and catalytic efficacy. Analysis of ER Ca2+ uptake in cells cotransfected with human wild-type SERCA2a (SERCA2aWT) and SERCA2a mutants with different catalytic activity revealed that an intact catalytic cycle in both protomers is required for enhancing the efficacy of Ca2+ transport by a dimer. The data are consistent with the hypothesis of functional coupling of two SERCA2a protomers in a dimer that reduces the energy barrier of rate-limiting steps of the catalytic cycle of Ca2+ transport.
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Ca 2+ Release via IP 3 Receptors Shapes the Cardiac Ca 2+ Transient for Hypertrophic Signaling. Biophys J 2020; 119:1178-1192. [PMID: 32871099 DOI: 10.1016/j.bpj.2020.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/16/2020] [Accepted: 08/04/2020] [Indexed: 12/27/2022] Open
Abstract
Calcium (Ca2+) plays a central role in mediating both contractile function and hypertrophic signaling in ventricular cardiomyocytes. L-type Ca2+ channels trigger release of Ca2+ from ryanodine receptors for cellular contraction, whereas signaling downstream of G-protein-coupled receptors stimulates Ca2+ release via inositol 1,4,5-trisphosphate receptors (IP3Rs), engaging hypertrophic signaling pathways. Modulation of the amplitude, duration, and duty cycle of the cytosolic Ca2+ contraction signal and spatial localization have all been proposed to encode this hypertrophic signal. Given current knowledge of IP3Rs, we develop a model describing the effect of functional interaction (cross talk) between ryanodine receptor and IP3R channels on the Ca2+ transient and examine the sensitivity of the Ca2+ transient shape to properties of IP3R activation. A key result of our study is that IP3R activation increases Ca2+ transient duration for a broad range of IP3R properties, but the effect of IP3R activation on Ca2+ transient amplitude is dependent on IP3 concentration. Furthermore we demonstrate that IP3-mediated Ca2+ release in the cytosol increases the duty cycle of the Ca2+ transient, the fraction of the cycle for which [Ca2+] is elevated, across a broad range of parameter values and IP3 concentrations. When coupled to a model of downstream transcription factor (NFAT) activation, we demonstrate that there is a high correspondence between the Ca2+ transient duty cycle and the proportion of activated NFAT in the nucleus. These findings suggest increased cytosolic Ca2+ duty cycle as a plausible mechanism for IP3-dependent hypertrophic signaling via Ca2+-sensitive transcription factors such as NFAT in ventricular cardiomyocytes.
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Transcriptomic Profiling of Ca2+ Transport Systems During the Formation of the Cerebral Cortex in Mice. Cells 2020; 9:cells9081800. [PMID: 32751129 PMCID: PMC7465657 DOI: 10.3390/cells9081800] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 01/05/2023] Open
Abstract
Cytosolic calcium (Ca2+) transients control key neural processes, including neurogenesis, migration, the polarization and growth of neurons, and the establishment and maintenance of synaptic connections. They are thus involved in the development and formation of the neural system. In this study, a publicly available whole transcriptome sequencing (RNA-Seq) dataset was used to examine the expression of genes coding for putative plasma membrane and organellar Ca2+-transporting proteins (channels, pumps, exchangers, and transporters) during the formation of the cerebral cortex in mice. Four ages were considered: embryonic days 11 (E11), 13 (E13), and 17 (E17), and post-natal day 1 (PN1). This transcriptomic profiling was also combined with live-cell Ca2+ imaging recordings to assess the presence of functional Ca2+ transport systems in E13 neurons. The most important Ca2+ routes of the cortical wall at the onset of corticogenesis (E11–E13) were TACAN, GluK5, nAChR β2, Cav3.1, Orai3, transient receptor potential cation channel subfamily M member 7 (TRPM7) non-mitochondrial Na+/Ca2+ exchanger 2 (NCX2), and the connexins CX43/CX45/CX37. Hence, transient receptor potential cation channel mucolipin subfamily member 1 (TRPML1), transmembrane protein 165 (TMEM165), and Ca2+ “leak” channels are prominent intracellular Ca2+ pathways. The Ca2+ pumps sarco/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) and plasma membrane Ca2+ ATPase 1 (PMCA1) control the resting basal Ca2+ levels. At the end of neurogenesis (E17 and onward), a more numerous and diverse population of Ca2+ uptake systems was observed. In addition to the actors listed above, prominent Ca2+-conducting systems of the cortical wall emerged, including acid-sensing ion channel 1 (ASIC1), Orai2, P2X2, and GluN1. Altogether, this study provides a detailed view of the pattern of expression of the main actors participating in the import, export, and release of Ca2+. This work can serve as a framework for further functional and mechanistic studies on Ca2+ signaling during cerebral cortex formation.
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Uryash A, Flores V, Adams JA, Allen PD, Lopez JR. Memory and Learning Deficits Are Associated With Ca 2+ Dyshomeostasis in Normal Aging. Front Aging Neurosci 2020; 12:224. [PMID: 32765253 PMCID: PMC7378956 DOI: 10.3389/fnagi.2020.00224] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/23/2020] [Indexed: 12/12/2022] Open
Abstract
Neuronal intracellular Ca2+ homeostasis is critical to the normal physiological functions of neurons and neuronal Ca2+ dyshomeostasis has been associated with the age-related decline of cognitive functions. Accumulated evidence indicates that the underlying mechanism for this is that abnormal intracellular Ca2+ levels stimulate the dysregulation of intracellular signaling, which subsequently induces neuronal cell death. We examined intracellular Ca2+ homeostasis in cortical (in vivo) and hippocampal (in vitro) neurons from young (3-months), middle-age (12-months), and aged (24-months) wild type C57BL6J mice. We found a progressive age-related elevation of intracellular resting calcium ([Ca2+]r) in cortical (in vivo) and hippocampal (in vitro) neurons associated with increased hippocampal neuronal calpain activity and reduced cell viability. In vitro, removal of extracellular Ca2+ or treatment with SAR7334 or dantrolene reduced [Ca2+]r in all age groups and dantrolene treatment lowered calpain activity and increased cell viability. In vivo, both middle-aged and aged mice showed cognitive deficits compared to young mice, which improved after dantrolene treatment. These findings support the hypothesis that intracellular Ca2+ dyshomeostasis is a major mechanism underlying the cognitive deficits seen in both normal aging and degenerative neurologic diseases.
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Affiliation(s)
- Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
| | - Valentina Flores
- Department of Research, Mount Sinai Medical Center, Miami, FL, United States
| | - Jose A. Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
| | - Paul D. Allen
- Malignant Hyperthermia Investigation Unit, St James’ University Hospital, University of Leeds, Leeds, United Kingdom
| | - Jose R. Lopez
- Department of Research, Mount Sinai Medical Center, Miami, FL, United States
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Rossi D, Gamberucci A, Pierantozzi E, Amato C, Migliore L, Sorrentino V. Calsequestrin, a key protein in striated muscle health and disease. J Muscle Res Cell Motil 2020; 42:267-279. [PMID: 32488451 DOI: 10.1007/s10974-020-09583-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/22/2020] [Accepted: 05/26/2020] [Indexed: 10/24/2022]
Abstract
Calsequestrin (CASQ) is the most abundant Ca2+ binding protein localized in the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle. The genome of vertebrates contains two genes, CASQ1 and CASQ2. CASQ1 and CASQ2 have a high level of homology, but show specific patterns of expression. Fast-twitch skeletal muscle fibers express only CASQ1, both CASQ1 and CASQ2 are present in slow-twitch skeletal muscle fibers, while CASQ2 is the only protein present in cardiomyocytes. Depending on the intraluminal SR Ca2+ levels, CASQ monomers assemble to form large polymers, which increase their Ca2+ binding ability. CASQ interacts with triadin and junctin, two additional SR proteins which contribute to localize CASQ to the junctional region of the SR (j-SR) and also modulate CASQ ability to polymerize into large macromolecular complexes. In addition to its ability to bind Ca2+ in the SR, CASQ appears also to be able to contribute to regulation of Ca2+ homeostasis in muscle cells. Both CASQ1 and CASQ2 are able to either activate and inhibit the ryanodine receptors (RyRs) calcium release channels, likely through their interactions with junctin and triadin. Additional evidence indicates that CASQ1 contributes to regulate the mechanism of store operated calcium entry in skeletal muscle via a direct interaction with the Stromal Interaction Molecule 1 (STIM1). Mutations in CASQ2 and CASQ1 have been identified, respectively, in patients with catecholamine-induced polymorphic ventricular tachycardia and in patients with some forms of myopathy. This review will highlight recent developments in understanding CASQ1 and CASQ2 in health and diseases.
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Affiliation(s)
- Daniela Rossi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy.
| | - Alessandra Gamberucci
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy
| | - Enrico Pierantozzi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy
| | - Caterina Amato
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy
| | - Loredana Migliore
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Via A. Moro, 2, 53100, Siena, Italy
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Valverde CA, Mazzocchi G, Di Carlo MN, Ciocci Pardo A, Salas N, Ragone MI, Felice JI, Cely-Ortiz A, Consolini AE, Portiansky E, Mosca S, Kranias EG, Wehrens XHT, Mattiazzi A. Ablation of phospholamban rescues reperfusion arrhythmias but exacerbates myocardium infarction in hearts with Ca2+/calmodulin kinase II constitutive phosphorylation of ryanodine receptors. Cardiovasc Res 2020; 115:556-569. [PMID: 30169578 DOI: 10.1093/cvr/cvy213] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/03/2018] [Accepted: 08/27/2018] [Indexed: 12/12/2022] Open
Abstract
AIMS Abnormal Ca2+ release from the sarcoplasmic reticulum (SR), associated with Ca2+-calmodulin kinase II (CaMKII)-dependent phosphorylation of RyR2 at Ser2814, has consistently been linked to arrhythmogenesis and ischaemia/reperfusion (I/R)-induced cell death. In contrast, the role played by SR Ca2+ uptake under these stress conditions remains controversial. We tested the hypothesis that an increase in SR Ca2+ uptake is able to attenuate reperfusion arrhythmias and cardiac injury elicited by increased RyR2-Ser2814 phosphorylation. METHODS AND RESULTS We used WT mice, which have been previously shown to exhibit a transient increase in RyR2-Ser2814 phosphorylation at the onset of reperfusion; mice with constitutive pseudo-phosphorylation of RyR2 at Ser2814 (S2814D) to exacerbate CaMKII-dependent reperfusion arrhythmias and cardiac damage, and phospholamban (PLN)-deficient-S2814D knock-in (SDKO) mice resulting from crossbreeding S2814D with phospholamban knockout deficient (PLNKO) mice. At baseline, S2814D and SDKO mice had structurally normal hearts. Moreover none of the strains were arrhythmic before ischaemia. Upon cardiac I/R, WT, and S2814D hearts exhibited abundant arrhythmias that were prevented by PLN ablation. In contrast, PLN ablation increased infarct size compared with WT and S2814D hearts. Mechanistically, the enhanced SR Ca2+ sequestration evoked by PLN ablation in SDKO hearts prevented arrhythmogenic events upon reperfusion by fragmenting SR Ca2+ waves into non-propagated and non-arrhythmogenic events (mini-waves). Conversely, the increase in SR Ca2+ sequestration did not reduce but rather exacerbated I/R-induced SR Ca2+ leak, as well as mitochondrial alterations, which were greatly avoided by inhibition of RyR2. These results indicate that the increase in SR Ca2+ uptake is ineffective in preventing the enhanced SR Ca2+ leak of PLN ablated myocytes from either entering into nearby mitochondria and/or activating additional CaMKII pathways, contributing to cardiac damage. CONCLUSION Our results demonstrate that increasing SR Ca2+ uptake by PLN ablation can prevent the arrhythmic events triggered by CaMKII-dependent phosphorylation of RyR2-induced SR Ca2+ leak. These findings underscore the benefits of increasing SERCA2a activity in the face of SR Ca2+ triggered arrhythmias. However, enhanced SERCA2a cannot prevent but rather exacerbates I/R cardiac injury.
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Affiliation(s)
- Carlos A Valverde
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Gabriela Mazzocchi
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Mariano N Di Carlo
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Alejandro Ciocci Pardo
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Nehuen Salas
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - María Ines Ragone
- Grupo de Farmacología Experimental, (GFEYEC), Departamento of Ciencias Biológicas, Facultad de Ciencias Exactas - CONICET., La Plata, Argentina
| | - Juan I Felice
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Alejandra Cely-Ortiz
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Alicia E Consolini
- Grupo de Farmacología Experimental, (GFEYEC), Departamento of Ciencias Biológicas, Facultad de Ciencias Exactas - CONICET., La Plata, Argentina
| | - Enrique Portiansky
- Laboratorio de Análisis de Imágenes, Facultad de Cs. Veterinarias, UNLP, La Plata, Argentina
| | - Susana Mosca
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
| | - Evangelia G Kranias
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA.,Department of Medicine (in Cardiology), Cardiovascular Research Institute, Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA.,Department of Pediatrics, Cardiovascular Research Institute, Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Alicia Mattiazzi
- Centro de Investigaciones Cardiovasculares 'Dr. Horacio E. Cingolani', CCT-La Plata-CONICET, Facultad de Cs. Médicas, UNLP, 60 y 120 s/n, La Plata CP, Argentina
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Gonano LA, Vila Petroff M. Direct Modulation of RyR2 Leading to a TRICky Ca 2+ Balance: The Effects of TRIC-A on Cardiac Muscle. Circ Res 2020; 126:436-438. [PMID: 32078455 DOI: 10.1161/circresaha.120.316532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Luis A Gonano
- From the Centro de Investigaciones Cardiovasculares, CONICET-CCT La Plata, Facultad de Ciencias Médicas, UNLP, 60 y 120, 1900 La Plata, Argentina
| | - Martin Vila Petroff
- From the Centro de Investigaciones Cardiovasculares, CONICET-CCT La Plata, Facultad de Ciencias Médicas, UNLP, 60 y 120, 1900 La Plata, Argentina
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Bovo E, Nikolaienko R, Bhayani S, Kahn D, Cao Q, Martin JL, Kuo IY, Robia SL, Zima AV. Novel approach for quantification of endoplasmic reticulum Ca 2+ transport. Am J Physiol Heart Circ Physiol 2019; 316:H1323-H1331. [PMID: 30901276 PMCID: PMC6620677 DOI: 10.1152/ajpheart.00031.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/01/2019] [Accepted: 03/04/2019] [Indexed: 01/14/2023]
Abstract
The type 2a sarco-/endoplasmic reticulum Ca2+-ATPase (SERCA2a) plays a key role in Ca2+ regulation in the heart. However, available techniques to study SERCA function are either cell destructive or lack sensitivity. The goal of this study was to develop an approach to selectively measure SERCA2a function in the cellular environment. The genetically encoded Ca2+ sensor R-CEPIA1er was used to measure the concentration of Ca2+ in the lumen of the endoplasmic reticulum (ER) ([Ca2+]ER) in HEK293 cells expressing human SERCA2a. Coexpression of the ER Ca2+ release channel ryanodine receptor (RyR2) created a Ca2+ release/reuptake system that mimicked aspects of cardiac myocyte Ca2+ handling. SERCA2a function was quantified from the rate of [Ca2+]ER refilling after ER Ca2+ depletion; then, ER Ca2+ leak was measured after SERCA inhibition. ER Ca2+ uptake and leak were analyzed as a function of [Ca2+]ER to determine maximum ER Ca2+ uptake rate and maximum ER Ca2+ load. The sensitivity of this assay was validated by analyzing effects of SERCA inhibitors, [ATP]/[ADP], oxidative stress, phospholamban, and a loss-of-function SERCA2a mutation. In addition, the feasibility of using R-CEPIA1er to study SERCA2a in a native system was evaluated by using in vivo gene delivery to express R-CEPIA1er in mouse hearts. After ventricular myocyte isolation, the same methodology used in HEK293 cells was applied to study endogenous SERCA2a. In conclusion, this new approach can be used as a sensitive screening tool to study the effect of different drugs, posttranslational modifications, and mutations on SERCA function. NEW & NOTEWORTHY The aim of this study was to develop a sensitive approach to selectively measure sarco-/endoplasmic reticulum Ca2+-ATPase (SERCA) function in the cellular environment. The newly developed Ca2+ sensor R-CEPIA1er was used to successfully analyze Ca2+ uptake mediated by recombinant and native cardiac SERCA. These results demonstrate that this new approach can be used as a powerful tool to study new mechanisms of Ca2+ pump regulation.
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Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Siddharth Bhayani
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Daniel Kahn
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Quan Cao
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Jody L Martin
- Department of Physiology and Biophysics, University of Illinois at Chicago , Chicago, Illinois
| | - Ivana Y Kuo
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago , Chicago, Illinois
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Mechanisms of Calcium Leak from Cardiac Sarcoplasmic Reticulum Revealed by Statistical Mechanics. Biophys J 2019; 116:2212-2223. [PMID: 31103231 DOI: 10.1016/j.bpj.2019.04.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 04/17/2019] [Accepted: 04/26/2019] [Indexed: 11/21/2022] Open
Abstract
Heart muscle contraction is normally activated by a synchronized Ca release from sarcoplasmic reticulum (SR), a major intracellular Ca store. However, under abnormal conditions, Ca leaks from the SR, decreasing heart contraction amplitude and increasing risk of life-threatening arrhythmia. The mechanisms and regimes of SR operation generating the abnormal Ca leak remain unclear. Here, we employed both numerical and analytical modeling to get mechanistic insights into the emergent Ca leak phenomenon. Our numerical simulations using a detailed realistic model of the Ca release unit reveal sharp transitions resulting in Ca leak. The emergence of leak is closely mapped mathematically to the Ising model from statistical mechanics. The system steady-state behavior is determined by two aggregate parameters: the analogs of magnetic field (h) and the inverse temperature (β) in the Ising model, for which we have explicit formulas in terms of SR [Ca] and release channel opening and closing rates. The classification of leak regimes takes the shape of a phase β-h diagram, with the regime boundaries occurring at h = 0 and a critical value of β (β∗) that we estimate using a classical Ising model and mean field theory. Our theory predicts that a synchronized Ca leak will occur when h > 0 and β >β∗, and a disordered leak occurs when β <β∗ and h is not too negative. The disorder leak is distinguished from synchronized leak (in long-lasting sparks) by larger Peierls contour lengths, an output parameter reflecting degree of disorder. Thus, in addition to our detailed numerical model approach, we also offer an instantaneous computational tool using analytical formulas of the Ising model for respective ryanodine receptor parameters and SR Ca load that describe and classify phase transitions and leak emergence.
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Fernández-Miranda G, Romero-Garcia T, Barrera-Lechuga TP, Mercado-Morales M, Rueda A. Impaired Activity of Ryanodine Receptors Contributes to Calcium Mishandling in Cardiomyocytes of Metabolic Syndrome Rats. Front Physiol 2019; 10:520. [PMID: 31114513 PMCID: PMC6503767 DOI: 10.3389/fphys.2019.00520] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 04/11/2019] [Indexed: 01/11/2023] Open
Abstract
Metabolic syndrome (MetS) has become a global epidemic. MetS is a serious health problem because of its related cardiovascular complications, which include hypertension and delayed heart rate recovery after exercise. The molecular bases of cardiac dysfunction in MetS are still under scrutiny and may be related to anomalies in the activity and expression of key proteins involved in the cardiac excitation-contraction coupling (ECC). The cardiac Ca2+ channel/ryanodine receptor (RyR2) participates in releasing Ca2+ from internal stores and plays a key role in the modulation of ECC. We examined alterations in expression, phosphorylation status, Ca2+ sensitivity, and in situ function (by measuring Ca2+ sparks and Ca2+ transients) of RyR2; alterations in these characteristics could help to explain the Ca2+ handling disturbances in MetS cardiomyocytes. MetS was induced in rats by adding commercially refined sugar (30% sucrose) to their drinking water for 24 weeks. Cardiomyocytes of MetS rats displayed decreased Ca2+ transient amplitude and cell contractility at all stimulation frequencies. Quiescent MetS cardiomyocytes showed a decrease in Ca2+ spark frequency, amplitude, and spark-mediated Ca2+ leak. The [3H]-ryanodine binding data showed that functionally active RyRs are significantly diminished in MetS heart microsomes; and exhibited rapid Ca2+-induced inactivation. The phosphorylation of corresponding Ser2814 (a preferential target for CaMKII) of the hRyR2 was significantly diminished. RyR2 protein expression and Ser2808 phosphorylation level were both unchanged. Further, we demonstrated that cardiomyocyte Ca2+ mishandling was associated with reduced SERCA pump activity due to decreased Thr17-PLN phosphorylation, suggesting a downregulation of CaMKII in MetS hearts, though the SR Ca2+ load remained unchanged. The reduction in the phosphorylation level of RyR2 at Ser2814 decreases RyR2 availability for activation during ECC. In conclusion, the impaired in situ activity of RyR2 may also account for the poor overall cardiac outcome reported in MetS patients; hence, the SERCA pump and RyR2 are both attractive potential targets for future therapies.
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Affiliation(s)
- Gaudencio Fernández-Miranda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Mexico City, Mexico
| | - Tatiana Romero-Garcia
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Mexico City, Mexico
| | - Tarín P Barrera-Lechuga
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Mexico City, Mexico
| | - Martha Mercado-Morales
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Mexico City, Mexico
| | - Angélica Rueda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Mexico City, Mexico
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Walweel K, Gomez-Hurtado N, Rebbeck RT, Oo YW, Beard NA, Molenaar P, Dos Remedios C, van Helden DF, Cornea RL, Knollmann BC, Laver DR. Calmodulin inhibition of human RyR2 channels requires phosphorylation of RyR2-S2808 or RyR2-S2814. J Mol Cell Cardiol 2019; 130:96-106. [PMID: 30928430 DOI: 10.1016/j.yjmcc.2019.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/19/2019] [Accepted: 03/25/2019] [Indexed: 01/08/2023]
Abstract
Calmodulin (CaM) is a Ca-binding protein that binds to, and can directly inhibit cardiac ryanodine receptor calcium release channels (RyR2). Animal studies have shown that RyR2 hyperphosphorylation reduces CaM binding to RyR2 in failing hearts, but data are lacking on how CaM regulates human RyR2 and how this regulation is affected by RyR2 phosphorylation. Physiological concentrations of CaM (100 nM) inhibited the diastolic activity of RyR2 isolated from failing human hearts by ~50% but had no effect on RyR2 from healthy human hearts. Using FRET between donor-FKBP12.6 and acceptor-CaM bound to RyR2, we determined that CaM binds to RyR2 from healthy human heart with a Kd = 121 ± 14 nM. Ex-vivo phosphorylation/dephosphorylation experiments suggested that the divergent CaM regulation of healthy and failing human RyR2 was caused by differences in RyR2 phosphorylation by protein kinase A and Ca-CaM-dependent kinase II. Ca2+-spark measurements in murine cardiomyocytes harbouring RyR2 phosphomimetic or phosphoablated mutants at S2814 and S2808 suggest that phosphorylation of residues corresponding to either human RyR2-S2808 or S2814 is both necessary and sufficient for RyR2 regulation by CaM. Our results challenge the current concept that CaM universally functions as a canonical inhibitor of RyR2 across species. Rather, CaM's biological action on human RyR2 appears to be more nuanced, with inhibitory activity only on phosphorylated RyR2 channels, which occurs during exercise or in patients with heart failure.
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Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
| | - Nieves Gomez-Hurtado
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Ye Wint Oo
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - Nicole A Beard
- Faculty of Science and Technology, University of Canberra, Bruce, ACT 2617, Australia.
| | - Peter Molenaar
- School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia; Northside Clinical School of Medicine, University of Queensland, Cardio-vascular Molecular & Therapeutics Translational Research Group, The Prince Charles Hospital, Chermside, QLD 4032. Australia.
| | - Cris Dos Remedios
- Bosch Institute, Discipline of Anatomy, University of Sydney, Sydney, New South Wales 2006, Australia.
| | - Dirk F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
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Xie Y, Yang Y, Galice S, Bers DM, Sato D. Size Matters: Ryanodine Receptor Cluster Size Heterogeneity Potentiates Calcium Waves. Biophys J 2019; 116:530-539. [PMID: 30686487 PMCID: PMC6369574 DOI: 10.1016/j.bpj.2018.12.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 11/11/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022] Open
Abstract
Ryanodine receptors (RyRs) mediate calcium (Ca)-induced Ca release and intracellular Ca homeostasis. In a cardiac myocyte, RyRs group into clusters of variable size from a few to several hundred RyRs, creating a spatially nonuniform intracellular distribution. It is unclear how heterogeneity of RyR cluster size alters spontaneous sarcoplasmic reticulum (SR) Ca releases (Ca sparks) and arrhythmogenic Ca waves. Here, we tested the impact of heterogeneous RyR cluster size on the initiation of Ca waves. Experimentally, we measured RyR cluster sizes at Ca spark sites in rat ventricular myocytes and further tested functional impacts using a physiologically detailed computational model with spatial and stochastic intracellular Ca dynamics. We found that the spark frequency and amplitude increase nonlinearly with the size of RyR clusters. Larger RyR clusters have lower SR Ca release threshold for local Ca spark initiation and exhibit steeper SR Ca release versus SR Ca load relationship. However, larger RyR clusters tend to lower SR Ca load because of the higher Ca leak rate. Conversely, smaller clusters have a higher threshold and a lower leak, which tends to increase SR Ca load. At the myocyte level, homogeneously large or small RyR clusters limit Ca waves (because of low load for large clusters but low excitability for small clusters). Mixtures of large and small RyR clusters potentiates Ca waves because the enhanced SR Ca load driven by smaller clusters enables Ca wave initiation and propagation from larger RyR clusters. Our study suggests that a spatially heterogeneous distribution of RyR cluster size under pathological conditions may potentiate Ca waves and thus afterdepolarizations and triggered arrhythmias.
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Affiliation(s)
- Yuanfang Xie
- Department of Pharmacology, University of California Davis, Davis, California
| | - Yi Yang
- Department of Pharmacology, University of California Davis, Davis, California
| | - Samuel Galice
- Department of Pharmacology, University of California Davis, Davis, California
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, California
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, California.
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Shen X, van den Brink J, Hou Y, Colli D, Le C, Kolstad TR, MacQuaide N, Carlson CR, Kekenes‐Huskey PM, Edwards AG, Soeller C, Louch WE. 3D dSTORM imaging reveals novel detail of ryanodine receptor localization in rat cardiac myocytes. J Physiol 2019; 597:399-418. [PMID: 30412283 PMCID: PMC6332759 DOI: 10.1113/jp277360] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 11/08/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Using 3D direct stochastic optical reconstruction microscopy (dSTORM), we developed novel approaches to quantitatively describe the nanoscale, 3D organization of ryanodine receptors (RyRs) in cardiomyocytes. Complex arrangements of RyR clusters were observed in 3D space, both at the cell surface and within the cell interior, with allocation to dyadic and non-dyadic pools. 3D imaging importantly allowed discernment of clusters overlapping in the z-axis, for which detection was obscured by conventional 2D imaging techniques. Thus, RyR clusters were found to be significantly smaller than previous 2D estimates. Ca2+ release units (CRUs), i.e. functional groupings of neighbouring RyR clusters, were similarly observed to be smaller than earlier reports. Internal CRUs contained more RyRs in more clusters than CRUs on the cell surface, and yielded longer duration Ca2+ sparks. ABSTRACT Cardiomyocyte contraction is dependent on Ca2+ release from ryanodine receptors (RyRs). However, the precise localization of RyRs remains unknown, due to shortcomings of imaging techniques which are diffraction limited or restricted to 2D. We aimed to determine the 3D nanoscale organization of RyRs in rat cardiomyocytes by employing direct stochastic optical reconstruction microscopy (dSTORM) with phase ramp technology. Initial observations at the cell surface showed an undulating organization of RyR clusters, resulting in their frequent overlap in the z-axis and obscured detection by 2D techniques. Non-overlapping clusters were imaged to create a calibration curve for estimating RyR number based on recorded fluorescence blinks. Employing this method at the cell surface and interior revealed smaller RyR clusters than 2D estimates, as erroneous merging of axially aligned RyRs was circumvented. Functional groupings of RyR clusters (Ca2+ release units, CRUs), contained an average of 18 and 23 RyRs at the surface and interior, respectively, although half of all CRUs contained only a single 'rogue' RyR. Internal CRUs were more tightly packed along z-lines than surface CRUs, contained larger and more numerous RyR clusters, and constituted ∼75% of the roughly 1 million RyRs present in an average cardiomyocyte. This complex internal 3D geometry was underscored by correlative imaging of RyRs and t-tubules, which enabled quantification of dyadic and non-dyadic RyR populations. Mirroring differences in CRU size and complexity, Ca2+ sparks originating from internal CRUs were of longer duration than those at the surface. These data provide novel, nanoscale insight into RyR organization and function across cardiomyocytes.
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Affiliation(s)
- Xin Shen
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
| | | | - Yufeng Hou
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
| | - Dylan Colli
- Department of ChemistryUniversity of KentuckyLexingtonKYUSA
| | - Christopher Le
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
| | - Terje R. Kolstad
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
| | - Niall MacQuaide
- Institute of Cardiovascular SciencesUniversity of GlasgowGlasgowUK
| | - Cathrine R. Carlson
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
| | | | | | | | - William E. Louch
- Institute for Experimental Medical ResearchOslo University Hospital and University of OsloNO‐0424OsloNorway
- KG Jebsen Center for Cardiac ResearchUniversity of OsloOsloNorway
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Nikolaienko R, Bovo E, Zima AV. Redox Dependent Modifications of Ryanodine Receptor: Basic Mechanisms and Implications in Heart Diseases. Front Physiol 2018; 9:1775. [PMID: 30574097 PMCID: PMC6291498 DOI: 10.3389/fphys.2018.01775] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 11/23/2018] [Indexed: 12/12/2022] Open
Abstract
Heart contraction vitally depends on tightly controlled intracellular Ca regulation. Because contraction is mainly driven by Ca released from the sarcoplasmic reticulum (SR), this organelle plays a particularly important role in Ca regulation. The type two ryanodine receptor (RyR2) is the major SR Ca release channel in ventricular myocytes. Several cardiac pathologies, including myocardial infarction and heart failure, are associated with increased RyR2 activity and diastolic SR Ca leak. It has been suggested that the increased RyR2 activity plays an important role in arrhythmias and contractile dysfunction. Several studies have linked increased SR Ca leak during myocardial infarction and heart failure to the activation of RyR2 in response to oxidative stress. This activation might include direct oxidation of RyR2 as well as indirect activation via phosphorylation or altered interactions with regulatory proteins. Out of ninety cysteine residues per RyR2 subunit, twenty one were reported to be in reduced state that could be potential targets for redox modifications that include S-nitrosylation, S-glutathionylation, and disulfide cross-linking. Despite its clinical significance, molecular mechanisms of RyR dysfunction during oxidative stress are not fully understood. Herein we review the most recent insights into redox-dependent modulation of RyR2 during oxidative stress and heart diseases.
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Affiliation(s)
- Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, United States
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, United States
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Kolstad TR, van den Brink J, MacQuaide N, Lunde PK, Frisk M, Aronsen JM, Norden ES, Cataliotti A, Sjaastad I, Sejersted OM, Edwards AG, Lines GT, Louch WE. Ryanodine receptor dispersion disrupts Ca 2+ release in failing cardiac myocytes. eLife 2018; 7:39427. [PMID: 30375974 PMCID: PMC6245731 DOI: 10.7554/elife.39427] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/24/2018] [Indexed: 12/22/2022] Open
Abstract
Reduced cardiac contractility during heart failure (HF) is linked to impaired Ca2+ release from Ryanodine Receptors (RyRs). We investigated whether this deficit can be traced to nanoscale RyR reorganization. Using super-resolution imaging, we observed dispersion of RyR clusters in cardiomyocytes from post-infarction HF rats, resulting in more numerous, smaller clusters. Functional groupings of RyR clusters which produce Ca2+ sparks (Ca2+ release units, CRUs) also became less solid. An increased fraction of small CRUs in HF was linked to augmented ‘silent’ Ca2+ leak, not visible as sparks. Larger multi-cluster CRUs common in HF also exhibited low fidelity spark generation. When successfully triggered, sparks in failing cells displayed slow kinetics as Ca2+ spread across dispersed CRUs. During the action potential, these slow sparks protracted and desynchronized the overall Ca2+ transient. Thus, nanoscale RyR reorganization during HF augments Ca2+ leak and slows Ca2+ release kinetics, leading to weakened contraction in this disease. The muscle cells of the heart coordinate how they contract and relax in order to produce the heartbeat. During heart failure, these cells become less able to contract. As a result the heart becomes inefficient, pumping less blood around the body. For the cardiac muscle cells to contract, the levels of calcium ions in the cells needs to rapidly increase. In failing hearts, these increases in calcium ion levels are smaller, slower and less well coordinated. It was not known what causes these changes, making it difficult to treat heart failure. Calcium ions are released in cardiac muscle cells through protein channels called ryanodine receptors. These receptors form clusters that allow them to synchronize when they open and close. Could the reorganization of ryanodine receptors account for the problems seen in failing hearts? To investigate, Kolstad et al. examined rat hearts using a technique called super-resolution microscopy. This showed that the clusters of ryanodine receptors break apart during heart failure to form smaller clusters. Further experiments showed that calcium ions ‘leak’ from these smaller clusters, reducing the amount of calcium that can be released into cardiac muscle cells during each heartbeat. Released calcium also spreads between the dispersed clusters, resulting in a slower rise of the calcium levels in the cells. Both changes contribute to weakened contractions of cells in failing hearts. Therefore, heart failure can be traced back to very small rearrangements of the ryanodine receptors. This understanding will help researchers as they investigate new ways to treat heart failure.
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Affiliation(s)
- Terje R Kolstad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | | | - Niall MacQuaide
- Institute of Cardiovascular Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Per Kristian Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jan Magnus Aronsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,Bjørknes College, Oslo, Norway
| | - Einar S Norden
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,Bjørknes College, Oslo, Norway
| | - Alessandro Cataliotti
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | | | | | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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47
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Mohamed BA, Hartmann N, Tirilomis P, Sekeres K, Li W, Neef S, Richter C, Zeisberg EM, Kattner L, Didié M, Guan K, Schmitto JD, Lehnart SE, Luther S, Voigt N, Seidler T, Sossalla S, Hasenfuss G, Toischer K. Sarcoplasmic reticulum calcium leak contributes to arrhythmia but not to heart failure progression. Sci Transl Med 2018; 10:10/458/eaan0724. [DOI: 10.1126/scitranslmed.aan0724] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 01/30/2018] [Accepted: 08/09/2018] [Indexed: 12/30/2022]
Abstract
Increased sarcoplasmic reticulum (SR) Ca2+ leak via the cardiac ryanodine receptor (RyR2) has been suggested to play a mechanistic role in the development of heart failure (HF) and cardiac arrhythmia. Mice treated with a selective RyR2 stabilizer, rycal S36, showed normalization of SR Ca2+ leak and improved survival in pressure overload (PO) and myocardial infarction (MI) models. The development of HF, measured by echocardiography and molecular markers, showed no difference in rycal S36– versus placebo-treated mice. Reduction of SR Ca2+ leak in the PO model by the rycal-unrelated RyR2 stabilizer dantrolene did not mitigate HF progression. Development of HF was not aggravated by increased SR Ca2+ leak due to RyR2 mutation (R2474S) in volume overload, an SR Ca2+ leak–independent HF model. Arrhythmia episodes were reduced by rycal S36 treatment in PO and MI mice in vivo and ex vivo in Langendorff-perfused hearts. Isolated cardiomyocytes from murine failing hearts and human ventricular failing and atrial nonfailing myocardium showed reductions in delayed afterdepolarizations, in spontaneous and induced Ca2+ waves, and in triggered activity in rycal S36 versus placebo cells, whereas the Ca2+ transient, SR Ca2+ load, SR Ca2+ adenosine triphosphatase function, and action potential duration were not affected. Rycal S36 treatment of human induced pluripotent stem cells isolated from a patient with catecholaminergic polymorphic ventricular tachycardia could rescue the leaky RyR2 receptor. These results suggest that SR Ca2+ leak does not primarily influence contractile HF progression, whereas rycal S36 treatment markedly reduces ventricular arrhythmias, thereby improving survival in mice.
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Affiliation(s)
- Belal A. Mohamed
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Mansoura University, Mansoura City 35516, Egypt
| | - Nico Hartmann
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
| | - Petros Tirilomis
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
| | - Karolina Sekeres
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Wener Li
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Stefan Neef
- Department of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany
| | - Claudia Richter
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Elisabeth M. Zeisberg
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Lars Kattner
- Endotherm Life Science Molecules, 66123 Saarbrücken, Germany
| | - Michael Didié
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Kaomei Guan
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Jan D. Schmitto
- Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany
| | - Stephan E. Lehnart
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- BioMET, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Stefan Luther
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Niels Voigt
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Tim Seidler
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Samuel Sossalla
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Department of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Karl Toischer
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
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Vinogradova TM, Tagirova Sirenko S, Lakatta EG. Unique Ca 2+-Cycling Protein Abundance and Regulation Sustains Local Ca 2+ Releases and Spontaneous Firing of Rabbit Sinoatrial Node Cells. Int J Mol Sci 2018; 19:ijms19082173. [PMID: 30044420 PMCID: PMC6121616 DOI: 10.3390/ijms19082173] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/20/2018] [Accepted: 07/23/2018] [Indexed: 11/16/2022] Open
Abstract
Spontaneous beating of the heart pacemaker, the sinoatrial node, is generated by sinoatrial node cells (SANC) and caused by gradual change of the membrane potential called diastolic depolarization (DD). Submembrane local Ca2+ releases (LCR) from sarcoplasmic reticulum (SR) occur during late DD and activate an inward Na+/Ca2+ exchange current, which accelerates the DD rate leading to earlier occurrence of an action potential. A comparison of intrinsic SR Ca2+ cycling revealed that, at similar physiological Ca2+ concentrations, LCRs are large and rhythmic in permeabilized SANC, but small and random in permeabilized ventricular myocytes (VM). Permeabilized SANC spontaneously released more Ca2+ from SR than VM, despite comparable SR Ca2+ content in both cell types. In this review we discuss specific patterns of expression and distribution of SR Ca2+ cycling proteins (SR Ca2+ ATPase (SERCA2), phospholamban (PLB) and ryanodine receptors (RyR)) in SANC and ventricular myocytes. We link ability of SANC to generate larger and rhythmic LCRs with increased abundance of SERCA2, reduced abundance of the SERCA inhibitor PLB. In addition, an increase in intracellular [Ca2+] increases phosphorylation of both PLB and RyR exclusively in SANC. The differences in SR Ca2+ cycling protein expression between SANC and VM provide insights into diverse regulation of intrinsic SR Ca2+ cycling that drives automaticity of SANC.
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Affiliation(s)
- Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
| | - Syevda Tagirova Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd, Room 8B-123, Baltimore, MD 21224, USA.
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49
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Bovo E, Mazurek SR, Zima AV. Oxidation of ryanodine receptor after ischemia-reperfusion increases propensity of Ca 2+ waves during β-adrenergic receptor stimulation. Am J Physiol Heart Circ Physiol 2018; 315:H1032-H1040. [PMID: 30028204 DOI: 10.1152/ajpheart.00334.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
β-Adrenergic receptor (β-AR) activation produces the main positive inotropic response of the heart. During ischemia-reperfusion (I/R), however, β-AR activation can trigger life-threatening arrhythmias. Because I/R is frequently associated with oxidative stress, we investigated whether ryanodine receptor (RyR) oxidation contributes to proarrythmogenic Ca2+ waves during β-AR activation. Measurements of contractile and electrical activity from Langendorff-perfused rabbit hearts revealed that I/R produces tachyarrhythmias. Ventricular myocytes isolated from I/R hearts had an increased level of oxidized glutathione (i.e., oxidative stress) and a decreased level of free thiols in RyRs (i.e., RyR oxidation). Furthermore, myocytes from I/R hearts were characterized by increased sarcoplasmic reticulum (SR) Ca2+ leak and enhanced fractional SR Ca2+ release. In myocytes from nonischemic hearts, β-AR activation with isoproterenol (10 nM) produced only a positive inotropic effect, whereas in myocytes from ischemic hearts, isoproterenol at the same concentration triggered spontaneous Ca2+ waves. β-AR activation produced a similar effect on RyR phosphorylation in control and I/R myocytes. Treatment of myocytes from I/R hearts with the reducing agent mercaptopropionylglycine (100 μM) attenuated RyR oxidization and decreased Ca2+ wave frequency during β-AR activation. On the other hand, treatment of myocytes from nonischemic hearts with H2O2 (50 μM) increased SR Ca2+ leak and triggered Ca2+ waves during β-AR activation. Collectively, these results suggest that RyR oxidation after I/R plays a critical role in the transition from positive inotropic to arrhythmogenic effects during β-AR stimulation. Prevention of RyR oxidation can be a promising strategy to inhibit arrhythmias and preserve positive inotropic effect of β-AR activation during myocardial infarction. NEW & NOTEWORTHY Oxidative stress induced by ischemia plays a critical role in triggering arrhythmias during adrenergic stimulation. The combined increase in sarcoplasmic reticulum Ca2+ leak (because of ryanodine receptor oxidation) and sarcoplasmic reticulum Ca2+ load (because of adrenergic stimulation) can trigger proarrythmogenic Ca2+ waves. Restoring normal ryanodine receptor redox status can be a promising strategy to prevent arrhythmias and preserve positive inotropic effect of adrenergic stimulation during myocardial infarction.
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Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago , Maywood, Illinois
| | - Stefan R Mazurek
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago , Maywood, Illinois
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago , Maywood, Illinois
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50
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Galice S, Xie Y, Yang Y, Sato D, Bers DM. Size Matters: Ryanodine Receptor Cluster Size Affects Arrhythmogenic Sarcoplasmic Reticulum Calcium Release. J Am Heart Assoc 2018; 7:e008724. [PMID: 29929992 PMCID: PMC6064922 DOI: 10.1161/jaha.118.008724] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/16/2018] [Indexed: 11/19/2022]
Abstract
BACKGROUND Ryanodine receptors (RyR) mediate sarcoplasmic reticulum calcium (Ca2+) release and influence myocyte Ca2+ homeostasis and arrhythmias. In cardiac myocytes, RyRs are found in clusters of various sizes and shapes, and RyR cluster size may critically influence normal and arrhythmogenic Ca2+ spark and wave formation. However, the actual RyR cluster sizes at specific Ca2+ spark sites have never been measured in the physiological setting. METHODS AND RESULTS Here we measured RyR cluster size and Ca2+ sparks simultaneously to assess how RyR cluster size influences Ca2+ sparks and sarcoplasmic reticulum Ca2+ leak. For small RyR cluster sizes (<50), Ca2+ spark frequency is very low but then increases dramatically at larger cluster sizes. In contrast, Ca2+ spark amplitude is nearly maximal even at relatively small RyR cluster size (≈10) and changes little at larger cluster size. These properties agreed with computational simulations of RyR gating within clusters. CONCLUSIONS Our study explains how this combination of properties may limit arrhythmogenic Ca2+ sparks and wave propagation (at many junctions) while preserving the efficacy and spatial synchronization of Ca2+-induced Ca2+-release during normal excitation-contraction coupling. However, variations in RyR cluster size among individual junctions and RyR sensitivity could exacerbate heterogeneity of local sarcoplasmic reticulum Ca2+ release and arrhythmogenesis under pathological conditions.
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Affiliation(s)
- Samuel Galice
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Yuanfang Xie
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Yi Yang
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA
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