1
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Thorpe MP, Blackwell DJ, Knollmann BC, Johnston JN. Backbone-Determined Antiarrhythmic Structure-Activity Relationships for a Mirror Image, Oligomeric Depsipeptide Natural Product. J Med Chem 2024; 67:12205-12220. [PMID: 38958200 DOI: 10.1021/acs.jmedchem.4c00923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Cyclic oligomeric depsipeptides (COD) are a structural class within naturally occurring compounds with a wide range of biological activity. Verticilide is a COD (24-membered ring) that was identified by its inhibition of insect ryanodine receptor (RyR). We have since found that the enantiomer of verticilide (ent-verticilide, 1) is a potent inhibitor of mammalian RyR2, a cardiac calcium channel, and therefore a potential antiarrhythmic agent. Oddly, nat-verticilide does not inhibit RyR2. To further develop ent-verticilide as an antiarrhythmic, we explored potential SAR through systematic modification of the ester's functionality to both N-H and N-Me amides. The syntheses of these ent-verticilide-inspired analogs are detailed using a monomer-based platform enabled by enantioselective catalysis. Two analogs among 23 exhibited measurable reduction of calcium sparks in a functional assay of RyR2 activity. These findings illustrate the value of natural product-inspired therapeutic development, but the less-studied approach where the non-natural enantiomeric series harbors important SAR.
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Affiliation(s)
- Madelaine P Thorpe
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Bjorn C Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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2
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Dotti P, Fernandez-Tenorio M, Janicek R, Márquez-Neila P, Wullschleger M, Sznitman R, Egger M. A deep learning-based approach for efficient detection and classification of local Ca²⁺ release events in Full-Frame confocal imaging. Cell Calcium 2024; 121:102893. [PMID: 38701707 DOI: 10.1016/j.ceca.2024.102893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/24/2024] [Accepted: 04/23/2024] [Indexed: 05/05/2024]
Abstract
The release of Ca2+ ions from intracellular stores plays a crucial role in many cellular processes, acting as a secondary messenger in various cell types, including cardiomyocytes, smooth muscle cells, hepatocytes, and many others. Detecting and classifying associated local Ca2+ release events is particularly important, as these events provide insight into the mechanisms, interplay, and interdependencies of local Ca2+release events underlying global intracellular Ca2+signaling. However, time-consuming and labor-intensive procedures often complicate analysis, especially with low signal-to-noise ratio imaging data. Here, we present an innovative deep learning-based approach for automatically detecting and classifying local Ca2+ release events. This approach is exemplified with rapid full-frame confocal imaging data recorded in isolated cardiomyocytes. To demonstrate the robustness and accuracy of our method, we first use conventional evaluation methods by comparing the intersection between manual annotations and the segmentation of Ca2+ release events provided by the deep learning method, as well as the annotated and recognized instances of individual events. In addition to these methods, we compare the performance of the proposed model with the annotation of six experts in the field. Our model can recognize more than 75 % of the annotated Ca2+ release events and correctly classify more than 75 %. A key result was that there were no significant differences between the annotations produced by human experts and the result of the proposed deep learning model. We conclude that the proposed approach is a robust and time-saving alternative to conventional full-frame confocal imaging analysis of local intracellular Ca2+ events.
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Affiliation(s)
- Prisca Dotti
- Department of Physiology, Universität Bern, Bern, Switzerland; ARTORG Center, Universität Bern, Bern, Switzerland
| | | | | | | | | | | | - Marcel Egger
- Department of Physiology, Universität Bern, Bern, Switzerland.
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3
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Eom Y, Kim SR, Kim YK, Lee SH. Mitochondrial Calcium Waves by Electrical Stimulation in Cultured Hippocampal Neurons. Mol Neurobiol 2024; 61:3477-3489. [PMID: 37995079 DOI: 10.1007/s12035-023-03795-w] [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: 04/24/2023] [Accepted: 10/31/2023] [Indexed: 11/24/2023]
Abstract
Mitochondria are critical to cellular Ca2+ homeostasis via the sequestering of cytosolic Ca2+ in the mitochondrial matrix. Mitochondrial Ca2+ buffering regulates neuronal activity and neuronal death by shaping cytosolic and presynaptic Ca2+ or controlling energy metabolism. Dysfunction in mitochondrial Ca2+ buffering has been implicated in psychological and neurological disorders. Ca2+ wave propagation refers to the spreading of Ca2+ for buffering and maintaining the associated rise in Ca2+ concentration. We investigated mitochondrial Ca2+ waves in hippocampal neurons using genetically encoded Ca2+ indicators. Neurons transfected with mito-GCaMP5G, mito-RCaMP1h, and CEPIA3mt exhibited evidence of mitochondrial Ca2+ waves with electrical stimulation. These waves were observed with 200 action potentials at 40 Hz or 20 Hz but not with lower frequencies or fewer action potentials. The application of inhibitors of mitochondrial calcium uniporter and oxidative phosphorylation suppressed mitochondrial Ca2+ waves. However, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and N-methyl-d-aspartate receptor blockade had no effect on mitochondrial Ca2+ wave were propagation. The Ca2+ waves were not observed in endoplasmic reticula, presynaptic terminals, or cytosol in association with electrical stimulation of 200 action potentials at 40 Hz. These results offer novel insights into the mechanisms underlying mitochondrial Ca2+ buffering and the molecular basis of mitochondrial Ca2+ waves in neurons in response to electrical stimulation.
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Affiliation(s)
- Yunkyung Eom
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sung Rae Kim
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
- Brain Research Core Facilities of Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea
| | - Yeong-Kyeong Kim
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Sung Hoon Lee
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea.
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4
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Mandracchia B, Zheng C, Rajendran S, Liu W, Forghani P, Xu C, Jia S. High-speed optical imaging with sCMOS pixel reassignment. Nat Commun 2024; 15:4598. [PMID: 38816394 PMCID: PMC11139943 DOI: 10.1038/s41467-024-48987-7] [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: 08/11/2023] [Accepted: 05/13/2024] [Indexed: 06/01/2024] Open
Abstract
Fluorescence microscopy has undergone rapid advancements, offering unprecedented visualization of biological events and shedding light on the intricate mechanisms governing living organisms. However, the exploration of rapid biological dynamics still poses a significant challenge due to the limitations of current digital camera architectures and the inherent compromise between imaging speed and other capabilities. Here, we introduce sHAPR, a high-speed acquisition technique that leverages the operating principles of sCMOS cameras to capture fast cellular and subcellular processes. sHAPR harnesses custom fiber optics to convert microscopy images into one-dimensional recordings, enabling acquisition at the maximum camera readout rate, typically between 25 and 250 kHz. We have demonstrated the utility of sHAPR with a variety of phantom and dynamic systems, including high-throughput flow cytometry, cardiomyocyte contraction, and neuronal calcium waves, using a standard epi-fluorescence microscope. sHAPR is highly adaptable and can be integrated into existing microscopy systems without requiring extensive platform modifications. This method pushes the boundaries of current fluorescence imaging capabilities, opening up new avenues for investigating high-speed biological phenomena.
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Affiliation(s)
- Biagio Mandracchia
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
- E.T.S.I. Telecomunicación, Universidad de Valladolid, Valladolid, Spain
| | - Corey Zheng
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Suraj Rajendran
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Wenhao Liu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Parvin Forghani
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Chunhui Xu
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, USA
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Shu Jia
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.
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5
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Sanders KM, Drumm BT, Cobine CA, Baker SA. Ca 2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract. Physiol Rev 2024; 104:329-398. [PMID: 37561138 PMCID: PMC11281822 DOI: 10.1152/physrev.00036.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 06/29/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
| | - Bernard T Drumm
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caroline A Cobine
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Salah A Baker
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada-Reno, Reno, Nevada, United States
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6
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Eisner D, Neher E, Taschenberger H, Smith G. Physiology of intracellular calcium buffering. Physiol Rev 2023; 103:2767-2845. [PMID: 37326298 DOI: 10.1152/physrev.00042.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/08/2023] [Accepted: 06/11/2023] [Indexed: 06/17/2023] Open
Abstract
Calcium signaling underlies much of physiology. Almost all the Ca2+ in the cytoplasm is bound to buffers, with typically only ∼1% being freely ionized at resting levels in most cells. Physiological Ca2+ buffers include small molecules and proteins, and experimentally Ca2+ indicators will also buffer calcium. The chemistry of interactions between Ca2+ and buffers determines the extent and speed of Ca2+ binding. The physiological effects of Ca2+ buffers are determined by the kinetics with which they bind Ca2+ and their mobility within the cell. The degree of buffering depends on factors such as the affinity for Ca2+, the Ca2+ concentration, and whether Ca2+ ions bind cooperatively. Buffering affects both the amplitude and time course of cytoplasmic Ca2+ signals as well as changes of Ca2+ concentration in organelles. It can also facilitate Ca2+ diffusion inside the cell. Ca2+ buffering affects synaptic transmission, muscle contraction, Ca2+ transport across epithelia, and the killing of bacteria. Saturation of buffers leads to synaptic facilitation and tetanic contraction in skeletal muscle and may play a role in inotropy in the heart. This review focuses on the link between buffer chemistry and function and how Ca2+ buffering affects normal physiology and the consequences of changes in disease. As well as summarizing what is known, we point out the many areas where further work is required.
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Affiliation(s)
- David Eisner
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Erwin Neher
- Membrane Biophysics Laboratory, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Godfrey Smith
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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7
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Magyar ZÉ, Bauer J, Bauerová-Hlinková V, Jóna I, Gaburjakova J, Gaburjakova M, Almássy J. Eu 3+ detects two functionally distinct luminal Ca 2+ binding sites in ryanodine receptors. Biophys J 2023; 122:3516-3531. [PMID: 37533257 PMCID: PMC10502479 DOI: 10.1016/j.bpj.2023.07.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/26/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023] Open
Abstract
Ryanodine receptors (RyRs) are Ca2+ release channels, gated by Ca2+ in the cytosol and the sarcoplasmic reticulum lumen. Their regulation is impaired in certain cardiac and muscle diseases. Although a lot of data is available on the luminal Ca2+ regulation of RyR, its interpretation is complicated by the possibility that the divalent ions used to probe the luminal binding sites may contaminate the cytoplasmic sites by crossing the channel pore. In this study, we used Eu3+, an impermeable agonist of Ca2+ binding sites, as a probe to avoid this complication and to gain more specific information about the function of the luminal Ca2+ sensor. Single-channel currents were measured from skeletal muscle and cardiac RyRs (RyR1 and RyR2) using the lipid bilayer technique. We show that RyR2 is activated by the luminal addition of Ca2+, whereas RyR1 is inhibited. These results were qualitatively reproducible using Eu3+. The luminal regulation of RyR1 carrying a mutation associated with malignant hyperthermia was not different from that of the wild-type. RyR1 inhibition by Eu3+ was extremely voltage dependent, whereas RyR2 activation did not depend on the membrane potential. These results suggest that the RyR1 inhibition site is in the membrane's electric field (channel pore), whereas the RyR2 activation site is outside. Using in silico analysis and previous results, we predicted putative Ca2+ binding site sequences. We propose that RyR2 bears an activation site, which is missing in RyR1, but both isoforms share the same inhibitory Ca2+ binding site near the channel gate.
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Affiliation(s)
- Zsuzsanna É Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jacob Bauer
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | - István Jóna
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jana Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Marta Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - János Almássy
- Department of Physiology, Semmelweis University, Budapest, Hungary.
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8
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Tomek J, Nieves-Cintron M, Navedo MF, Ko CY, Bers DM. SparkMaster 2: A New Software for Automatic Analysis of Calcium Spark Data. Circ Res 2023; 133:450-462. [PMID: 37555352 PMCID: PMC7615009 DOI: 10.1161/circresaha.123.322847] [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: 03/28/2023] [Revised: 07/22/2023] [Accepted: 07/26/2023] [Indexed: 08/10/2023]
Abstract
BACKGROUND Calcium (Ca) sparks are elementary units of subcellular Ca release in cardiomyocytes and other cells. Accordingly, Ca spark imaging is an essential tool for understanding the physiology and pathophysiology of Ca handling and is used to identify new drugs targeting Ca-related cellular dysfunction (eg, cardiac arrhythmias). The large volumes of imaging data produced during such experiments require accurate and high-throughput analysis. METHODS We developed a new software tool SparkMaster 2 (SM2) for the analysis of Ca sparks imaged by confocal line-scan microscopy, combining high accuracy, flexibility, and user-friendliness. SM2 is distributed as a stand-alone application requiring no installation. It can be controlled using a simple-to-use graphical user interface, or using Python scripting. RESULTS SM2 is shown to have the following strengths: (1) high accuracy at identifying Ca release events, clearly outperforming previous highly successful software SparkMaster; (2) multiple types of Ca release events can be identified using SM2: Ca sparks, waves, miniwaves, and long sparks; (3) SM2 can accurately split and analyze individual sparks within spark clusters, a capability not handled adequately by prior tools. We demonstrate the practical utility of SM2 in two case studies, investigating how Ca levels affect spontaneous Ca release, and how large-scale release events may promote release refractoriness. SM2 is also useful in atrial and smooth muscle myocytes, across different imaging conditions. CONCLUSIONS SparkMaster 2 is a new, much-improved user-friendly software for accurate high-throughput analysis of line-scan Ca spark imaging data. It is free, easy to use, and provides valuable built-in features to facilitate visualization, analysis, and interpretation of Ca spark data. It should enhance the quality and throughput of Ca spark and wave analysis across cell types, particularly in the study of arrhythmogenic Ca release events in cardiomyocytes.
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Affiliation(s)
- Jakub Tomek
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, California (J.T., M.N.-C., M.F.N., C.Y.K., D.M.B.)
- Department of Anatomy, Physiology, and Genetics, University of Oxford, Oxford, UK (J.T.)
| | - Madeline Nieves-Cintron
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, California (J.T., M.N.-C., M.F.N., C.Y.K., D.M.B.)
| | - Manuel F. Navedo
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, California (J.T., M.N.-C., M.F.N., C.Y.K., D.M.B.)
| | - Christopher Y. Ko
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, California (J.T., M.N.-C., M.F.N., C.Y.K., D.M.B.)
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis School of Medicine, Davis, California (J.T., M.N.-C., M.F.N., C.Y.K., D.M.B.)
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9
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Ferreira G, Cardozo R, Sastre S, Costa C, Santander A, Chavarría L, Guizzo V, Puglisi J, Nicolson GL. Bacterial toxins and heart function: heat-labile Escherichia coli enterotoxin B promotes changes in cardiac function with possible relevance for sudden cardiac death. Biophys Rev 2023; 15:447-473. [PMID: 37681088 PMCID: PMC10480140 DOI: 10.1007/s12551-023-01100-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/11/2023] [Indexed: 09/09/2023] Open
Abstract
Bacterial toxins can cause cardiomyopathy, though it is not its most common cause. Some bacterial toxins can form pores in the membrane of cardiomyocytes, while others can bind to membrane receptors. Enterotoxigenic E. coli can secrete enterotoxins, including heat-resistant (ST) or labile (LT) enterotoxins. LT is an AB5-type toxin that can bind to specific cell receptors and disrupt essential host functions, causing several common conditions, such as certain diarrhea. The pentameric B subunit of LT, without A subunit (LTB), binds specifically to certain plasma membrane ganglioside receptors, found in lipid rafts of cardiomyocytes. Isolated guinea pig hearts and cardiomyocytes were exposed to different concentrations of purified LTB. In isolated hearts, mechanical and electrical alternans and an increment of heart rate variability, with an IC50 of ~0.2 μg/ml LTB, were observed. In isolated cardiomyocytes, LTB promoted significant decreases in the amplitude and the duration of action potentials. Na+ currents were inhibited whereas L-type Ca2+ currents were augmented at their peak and their fast inactivation was promoted. Delayed rectifier K+ currents decreased. Measurements of basal Ca2+ or Ca2+ release events in cells exposed to LTB suggest that LTB impairs Ca2+ homeostasis. Impaired calcium homeostasis is linked to sudden cardiac death. The results are consistent with the recent view that the B subunit is not merely a carrier of the A subunit, having a role explaining sudden cardiac death in children (SIDS) infected with enterotoxigenic E. coli, explaining several epidemiological findings that establish a strong relationship between SIDS and ETEC E. coli. Supplementary Information The online version contains supplementary material available at 10.1007/s12551-023-01100-6.
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Affiliation(s)
- Gonzalo Ferreira
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Romina Cardozo
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Santiago Sastre
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics and Centro de Investigaciones Biomédicas (CeInBio), Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Carlos Costa
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Axel Santander
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Luisina Chavarría
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - Valentina Guizzo
- Ion Channels, Biological Membranes and Cell Signaling Laboratory, Dept. Of Biophysics, Facultad de Medicina, Universidad de la Republica, Gral Flores 2125, 11800 Montevideo, CP Uruguay
| | - José Puglisi
- College of Medicine, California North State University, 9700 West Taron Drive, Elk Grove, CA 95757 USA
| | - G. L. Nicolson
- Institute for Molecular Medicine, Beach, Huntington, CA USA
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10
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Smith HA, Thillaiappan NB, Rossi AM. IP 3 receptors: An "elementary" journey from structure to signals. Cell Calcium 2023; 113:102761. [PMID: 37271052 DOI: 10.1016/j.ceca.2023.102761] [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: 03/07/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/06/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are large tetrameric channels which sit mostly in the membrane of the endoplasmic reticulum (ER) and mediate Ca2+ release from intracellular stores in response to extracellular stimuli in almost all cells. Dual regulation of IP3Rs by IP3 and Ca2+ itself, upstream "licensing", and the arrangement of IP3Rs into small clusters in the ER membrane, allow IP3Rs to generate spatially and temporally diverse Ca2+ signals. The characteristic biphasic regulation of IP3Rs by cytosolic Ca2+ concentration underpins regenerative Ca2+ signals by Ca2+-induced Ca2+-release, while also preventing uncontrolled explosive Ca2+ release. In this way, cells can harness a simple ion such as Ca2+ as a near-universal intracellular messenger to regulate diverse cellular functions, including those with conflicting outcomes such as cell survival and cell death. High-resolution structures of the IP3R bound to IP3 and Ca2+ in different combinations have together started to unravel the workings of this giant channel. Here we discuss, in the context of recently published structures, how the tight regulation of IP3Rs and their cellular geography lead to generation of "elementary" local Ca2+ signals known as Ca2+ "puffs", which form the fundamental bottleneck through which all IP3-mediated cytosolic Ca2+ signals must first pass.
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Affiliation(s)
- Holly A Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | | | - Ana M Rossi
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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11
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Hou Y, Laasmaa M, Li J, Shen X, Manfra O, Norden ES, Le C, Zhang L, Sjaastad I, Jones PP, Soeller C, Louch WE. Live-cell photo-activated localization microscopy correlates nanoscale ryanodine receptor configuration to calcium sparks in cardiomyocytes. NATURE CARDIOVASCULAR RESEARCH 2023; 2:251-267. [PMID: 38803363 PMCID: PMC7616007 DOI: 10.1038/s44161-022-00199-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/24/2022] [Indexed: 05/29/2024]
Abstract
Ca2+ sparks constitute the fundamental units of Ca2+ release in cardiomyocytes. Here we investigate how ryanodine receptors (RyRs) collectively generate these events by employing a transgenic mouse with a photo-activated label on RyR2. This allowed correlative imaging of RyR localization, by super-resolution Photo-Activated Localization Microscopy, and Ca2+ sparks, by high-speed imaging. Two populations of Ca2+ sparks were observed: stationary events and "travelling" events that spread between neighbouring RyR clusters. Travelling sparks exhibited up to 8 distinct releases, sourced from local or distal junctional sarcoplasmic reticulum. Quantitative analyses showed that sparks may be triggered by any number of RyRs within a cluster, and that acute β-adrenergic stimulation augments intra-cluster RyR recruitment to generate larger events. In contrast, RyR "dispersion" during heart failure facilitates the generation of travelling sparks. Thus, RyRs cooperatively generate Ca2+ sparks in a complex, malleable fashion, and channel organization regulates the propensity for local propagation of Ca2+ release.
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Affiliation(s)
- Yufeng Hou
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Martin Laasmaa
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Ornella Manfra
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Einar S. Norden
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
| | - Lili Zhang
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Peter P. Jones
- Department of Physiology, School of Biomedical Sciences and HeartOtago, University of Otago, Dunedin, New Zealand
| | | | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, NO-0424 Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
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12
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Abstract
Cardiac alternans arises from dynamical instabilities in the electrical and calcium cycling systems of the heart, and often precedes ventricular arrhythmias and sudden cardiac death. In this review, we integrate clinical observations with theory and experiment to paint a holistic portrait of cardiac alternans: the underlying mechanisms, arrhythmic manifestations and electrocardiographic signatures. We first summarize the cellular and tissue mechanisms of alternans that have been demonstrated both theoretically and experimentally, including 3 voltage-driven and 2 calcium-driven alternans mechanisms. Based on experimental and simulation results, we describe their relevance to mechanisms of arrhythmogenesis under different disease conditions, and their link to electrocardiographic characteristics of alternans observed in patients. Our major conclusion is that alternans is not only a predictor, but also a causal mechanism of potentially lethal ventricular and atrial arrhythmias across the full spectrum of arrhythmia mechanisms that culminate in functional reentry, although less important for anatomic reentry and focal arrhythmias.
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Affiliation(s)
- Zhilin Qu
- Departments of Medicine (Cardiology), Physiology, and Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - James N. Weiss
- Departments of Medicine (Cardiology), Physiology, and Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA
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13
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Clemens DJ, Ye D, Zhou W, Kim CSJ, Pease DR, Navaratnarajah CK, Barkhymer A, Tester DJ, Nelson TJ, Cattaneo R, Schneider JW, Ackerman MJ. SARS-CoV-2 spike protein-mediated cardiomyocyte fusion may contribute to increased arrhythmic risk in COVID-19. PLoS One 2023; 18:e0282151. [PMID: 36888581 PMCID: PMC9994677 DOI: 10.1371/journal.pone.0282151] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 02/07/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND SARS-CoV-2-mediated COVID-19 may cause sudden cardiac death (SCD). Factors contributing to this increased risk of potentially fatal arrhythmias include thrombosis, exaggerated immune response, and treatment with QT-prolonging drugs. However, the intrinsic arrhythmic potential of direct SARS-CoV-2 infection of the heart remains unknown. OBJECTIVE To assess the cellular and electrophysiological effects of direct SARS-CoV-2 infection of the heart using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). METHODS hiPSC-CMs were transfected with recombinant SARS-CoV-2 spike protein (CoV-2 S) or CoV-2 S fused to a modified Emerald fluorescence protein (CoV-2 S-mEm). Cell morphology was visualized using immunofluorescence microscopy. Action potential duration (APD) and cellular arrhythmias were measured by whole cell patch-clamp. Calcium handling was assessed using the Fluo-4 Ca2+ indicator. RESULTS Transfection of hiPSC-CMs with CoV-2 S-mEm produced multinucleated giant cells (syncytia) displaying increased cellular capacitance (75±7 pF, n = 10 vs. 26±3 pF, n = 10; P<0.0001) consistent with increased cell size. The APD90 was prolonged significantly from 419±26 ms (n = 10) in untransfected hiPSC-CMs to 590±67 ms (n = 10; P<0.05) in CoV-2 S-mEm-transfected hiPSC-CMs. CoV-2 S-induced syncytia displayed delayed afterdepolarizations, erratic beating frequency, and calcium handling abnormalities including calcium sparks, large "tsunami"-like waves, and increased calcium transient amplitude. After furin protease inhibitor treatment or mutating the CoV-2 S furin cleavage site, cell-cell fusion was no longer evident and Ca2+ handling returned to normal. CONCLUSION The SARS-CoV-2 spike protein can directly perturb both the cardiomyocyte's repolarization reserve and intracellular calcium handling that may confer the intrinsic, mechanistic substrate for the increased risk of SCD observed during this COVID-19 pandemic.
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Affiliation(s)
- Daniel J. Clemens
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
| | - Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN, United States of America
| | - Wei Zhou
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN, United States of America
| | - C. S. John Kim
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN, United States of America
| | - David R. Pease
- Discovery Engine/Program for Hypoplastic Left Heart Syndrome, Mayo Clinic, Rochester, MN, United States of America
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN, United States of America
| | | | - Alison Barkhymer
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN, United States of America
| | - David J. Tester
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN, United States of America
| | - Timothy J. Nelson
- Discovery Engine/Program for Hypoplastic Left Heart Syndrome, Mayo Clinic, Rochester, MN, United States of America
- Wanek Family Program for HLHS-Stem Cell Pipeline, Mayo Clinic, Rochester, MN, United States of America
- Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN, United States of America
| | - Roberto Cattaneo
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN, United States of America
| | - Jay W. Schneider
- Discovery Engine/Program for Hypoplastic Left Heart Syndrome, Mayo Clinic, Rochester, MN, United States of America
| | - Michael J. Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, United States of America
- Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, MN, United States of America
- Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN, United States of America
- * E-mail:
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14
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McCoy MD, Ullah A, Lederer WJ, Jafri MS. Understanding Calmodulin Variants Affecting Calcium-Dependent Inactivation of L-Type Calcium Channels through Whole-Cell Simulation of the Cardiac Ventricular Myocyte. Biomolecules 2022; 13:72. [PMID: 36671457 PMCID: PMC9855640 DOI: 10.3390/biom13010072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
Mutations in the calcium-sensing protein calmodulin (CaM) have been linked to two cardiac arrhythmia diseases, Long QT Syndrome 14 (LQT14) and Catecholaminergic Polymorphic Ventricular Tachycardia Type 4 (CPVT4), with varying degrees of severity. Functional characterization of the CaM mutants most strongly associated with LQT14 show a clear disruption of the calcium-dependent inactivation (CDI) of the L-Type calcium channel (LCC). CPVT4 mutants on the other hand are associated with changes in their affinity to the ryanodine receptor. In clinical studies, some variants have been associated with both CPVT4 and LQT15. This study uses simulations in a model for excitation-contraction coupling in the rat ventricular myocytes to understand how LQT14 variant might give the functional phenotype similar to CPVT4. Changing the CaM-dependent transition rate by a factor of 0.75 corresponding to the D96V variant and by a factor of 0.90 corresponding to the F142L or N98S variants, in a physiologically based stochastic model of the LCC prolonger, the action potential duration changed by a small amount in a cardiac myocyte but did not disrupt CICR at 1, 2, and 4 Hz. Under beta-adrenergic simulation abnormal excitation-contraction coupling was observed above 2 Hz pacing for the mutant CaM. The same conditions applied under beta-adrenergic stimulation led to the rapid onset of arrhythmia in the mutant CaM simulations. Simulations with the LQT14 mutations under the conditions of rapid pacing with beta-adrenergic stimulation drives the cardiac myocyte toward an arrhythmic state known as Ca2+ overload. These simulations provide a mechanistic link to a disease state for LQT14-associated mutations in CaM to yield a CPVT4 phenotype. The results show that small changes to the CaM-regulated inactivation of LCC promote arrhythmia and underscore the significance of CDI in proper heart function.
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Affiliation(s)
- Matthew D. McCoy
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
- Innovation Center for Biomedical Informatics, Department of Oncology, Georgetown University Medical Center, Georgetown University, Washington, DC 20057, USA
| | - Aman Ullah
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
| | - W. Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA
| | - M. Saleet Jafri
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA
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15
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Qu Z, Yan D, Song Z. Modeling Calcium Cycling in the Heart: Progress, Pitfalls, and Challenges. Biomolecules 2022; 12:1686. [PMID: 36421700 PMCID: PMC9687412 DOI: 10.3390/biom12111686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Intracellular calcium (Ca) cycling in the heart plays key roles in excitation-contraction coupling and arrhythmogenesis. In cardiac myocytes, the Ca release channels, i.e., the ryanodine receptors (RyRs), are clustered in the sarcoplasmic reticulum membrane, forming Ca release units (CRUs). The RyRs in a CRU act collectively to give rise to discrete Ca release events, called Ca sparks. A cell contains hundreds to thousands of CRUs, diffusively coupled via Ca to form a CRU network. A rich spectrum of spatiotemporal Ca dynamics is observed in cardiac myocytes, including Ca sparks, spark clusters, mini-waves, persistent whole-cell waves, and oscillations. Models of different temporal and spatial scales have been developed to investigate these dynamics. Due to the complexities of the CRU network and the spatiotemporal Ca dynamics, it is challenging to model the Ca cycling dynamics in the cardiac system, particularly at the tissue sales. In this article, we review the progress of modeling of Ca cycling in cardiac systems from single RyRs to the tissue scale, the pros and cons of the current models and different modeling approaches, and the challenges to be tackled in the future.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, A2-237 CHS, 650 Charles E. Young Drive South, Los Angeles, CA 90095, USA
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Dasen Yan
- Peng Cheng Laboratory, Shenzhen 518066, China
| | - Zhen Song
- Peng Cheng Laboratory, Shenzhen 518066, China
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16
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Wang BX, Kane C, Nicastro L, King O, Kit-Anan W, Downing B, Deidda G, Couch LS, Pinali C, Mitraki A, MacLeod KT, Terracciano CM. Integrins Increase Sarcoplasmic Reticulum Activity for Excitation-Contraction Coupling in Human Stem Cell-Derived Cardiomyocytes. Int J Mol Sci 2022; 23:10940. [PMID: 36142853 PMCID: PMC9504605 DOI: 10.3390/ijms231810940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/10/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Engagement of the sarcoplasmic reticulum (SR) Ca2+ stores for excitation-contraction (EC)-coupling is a fundamental feature of cardiac muscle cells. Extracellular matrix (ECM) proteins that form the extracellular scaffolding supporting cardiac contractile activity are thought to play an integral role in the modulation of EC-coupling. At baseline, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) show poor utilisation of SR Ca2+ stores, leading to inefficient EC-coupling, like developing or human CMs in cardiac diseases such as heart failure. We hypothesised that integrin ligand-receptor interactions between ECM proteins and CMs recruit the SR to Ca2+ cycling during EC-coupling. hiPSC-CM monolayers were cultured on fibronectin-coated glass before 24 h treatment with fibril-forming peptides containing the integrin-binding tripeptide sequence arginine-glycine-aspartic acid (2 mM). Micropipette application of 40 mM caffeine in standard or Na+/Ca2+-free Tyrode's solutions was used to assess the Ca2+ removal mechanisms. Microelectrode recordings were conducted to analyse action potentials in current-clamp. Confocal images of labelled hiPSC-CMs were analysed to investigate hiPSC-CM morphology and ultrastructural arrangements in Ca2+ release units. This study demonstrates that peptides containing the integrin-binding sequence arginine-glycine-aspartic acid (1) abbreviate hiPSC-CM Ca2+ transient and action potential duration, (2) increase co-localisation between L-type Ca2+ channels and ryanodine receptors involved in EC-coupling, and (3) increase the rate of SR-mediated Ca2+ cycling. We conclude that integrin-binding peptides induce recruitment of the SR for Ca2+ cycling in EC-coupling through functional and structural improvements and demonstrate the importance of the ECM in modulating cardiomyocyte function in physiology.
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Affiliation(s)
- Brian X. Wang
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London SW7 2AZ, UK
| | - Christopher Kane
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Laura Nicastro
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Oisín King
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
- Human Safety, Bayer Crop Science, 06903 Sophia-Antipolis, France
| | - Worrapong Kit-Anan
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Barrett Downing
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Graziano Deidda
- Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology−Hellas (FORTH), 700 13 Heraklion, Greece
- Department of Materials Science and Technology, University of Crete, 700 13 Heraklion, Greece
| | - Liam S. Couch
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Christian Pinali
- Division of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, UK
| | - Anna Mitraki
- Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology−Hellas (FORTH), 700 13 Heraklion, Greece
- Department of Materials Science and Technology, University of Crete, 700 13 Heraklion, Greece
| | - Kenneth T. MacLeod
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Cesare M. Terracciano
- National Heart & Lung Institute, Imperial College London, London SW7 2AZ, UK
- Laboratory of Myocardial Electrophysiology, 4th Floor, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
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17
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Guarina L, Moghbel AN, Pourhosseinzadeh MS, Cudmore RH, Sato D, Clancy CE, Santana LF. Biological noise is a key determinant of the reproducibility and adaptability of cardiac pacemaking and EC coupling. J Gen Physiol 2022; 154:213185. [PMID: 35482009 PMCID: PMC9059386 DOI: 10.1085/jgp.202012613] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/16/2022] [Accepted: 04/07/2022] [Indexed: 12/23/2022] Open
Abstract
Each heartbeat begins with the generation of an action potential in pacemaking cells in the sinoatrial node. This signal triggers contraction of cardiac muscle through a process termed excitation-contraction (EC) coupling. EC coupling is initiated in dyadic structures of cardiac myocytes, where ryanodine receptors in the junctional sarcoplasmic reticulum come into close apposition with clusters of CaV1.2 channels in invaginations of the sarcolemma. Cooperative activation of CaV1.2 channels within these clusters causes a local increase in intracellular Ca2+ that activates the juxtaposed ryanodine receptors. A salient feature of healthy cardiac function is the reliable and precise beat-to-beat pacemaking and amplitude of Ca2+ transients during EC coupling. In this review, we discuss recent discoveries suggesting that the exquisite reproducibility of this system emerges, paradoxically, from high variability at subcellular, cellular, and network levels. This variability is attributable to stochastic fluctuations in ion channel trafficking, clustering, and gating, as well as dyadic structure, which increase intracellular Ca2+ variance during EC coupling. Although the effects of these large, local fluctuations in function and organization are sometimes negligible at the macroscopic level owing to spatial-temporal summation within and across cells in the tissue, recent work suggests that the "noisiness" of these intracellular Ca2+ events may either enhance or counterintuitively reduce variability in a context-dependent manner. Indeed, these noisy events may represent distinct regulatory features in the tuning of cardiac contractility. Collectively, these observations support the importance of incorporating experimentally determined values of Ca2+ variance in all EC coupling models. The high reproducibility of cardiac contraction is a paradoxical outcome of high Ca2+ signaling variability at subcellular, cellular, and network levels caused by stochastic fluctuations in multiple processes in time and space. This underlying stochasticity, which counterintuitively manifests as reliable, consistent Ca2+ transients during EC coupling, also allows for rapid changes in cardiac rhythmicity and contractility in health and disease.
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Affiliation(s)
- Laura Guarina
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Ariana Neelufar Moghbel
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | | | - Robert H Cudmore
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis School of Medicine, Davis, CA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Luis Fernando Santana
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
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18
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Abstract
Flecainide, a cardiac class 1C blocker of the surface membrane sodium channel (NaV1.5), has also been reported to reduce cardiac ryanodine receptor (RyR2)-mediated sarcoplasmic reticulum (SR) Ca2+ release. It has been introduced as a clinical antiarrhythmic agent for catecholaminergic polymorphic ventricular tachycardia (CPVT), a condition most commonly associated with gain-of-function RyR2 mutations. Current debate concerns both cellular mechanisms of its antiarrhythmic action and molecular mechanisms of its RyR2 actions. At the cellular level, it targets NaV1.5, RyR2, Na+/Ca2+ exchange (NCX), and additional proteins involved in excitation-contraction (EC) coupling and potentially contribute to the CPVT phenotype. This Viewpoint primarily addresses the various direct molecular actions of flecainide on isolated RyR2 channels in artificial lipid bilayers. Such studies demonstrate different, multifarious, flecainide binding sites on RyR2, with voltage-dependent binding in the channel pore or voltage-independent binding at distant peripheral sites. In contrast to its single NaV1.5 pore binding site, flecainide may bind to at least four separate inhibitory sites on RyR2 and one activation site. None of these binding sites have been specifically located in the linear RyR2 sequence or high-resolution structure. Furthermore, it is not clear which of the inhibitory sites contribute to flecainide's reduction of spontaneous Ca2+ release in cellular studies. A confounding observation is that flecainide binding to voltage-dependent inhibition sites reduces cation fluxes in a direction opposite to physiological Ca2+ flow from SR lumen to cytosol. This may suggest that, rather than directly blocking Ca2+ efflux, flecainide can reduce Ca2+ efflux by blocking counter currents through the pore which otherwise limit SR membrane potential change during systolic Ca2+ efflux. In summary, the antiarrhythmic effects of flecainide in CPVT seem to involve multiple components of EC coupling and multiple actions on RyR2. Their clarification may identify novel specific drug targets and facilitate flecainide's clinical utilization in CPVT.
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Affiliation(s)
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - James A. Fraser
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Acton, Australia
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19
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Kim AA, Nguyen A, Marchetti M, Du X, Montell DJ, Pruitt BL, O'Brien LE. Independently paced Ca2+ oscillations in progenitor and differentiated cells in an ex vivo epithelial organ. J Cell Sci 2022; 135:jcs260249. [PMID: 35722729 PMCID: PMC9450890 DOI: 10.1242/jcs.260249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 11/22/2022] Open
Abstract
Cytosolic Ca2+ is a highly dynamic, tightly regulated and broadly conserved cellular signal. Ca2+ dynamics have been studied widely in cellular monocultures, yet organs in vivo comprise heterogeneous populations of stem and differentiated cells. Here, we examine Ca2+ dynamics in the adult Drosophila intestine, a self-renewing epithelial organ in which stem cells continuously produce daughters that differentiate into either enteroendocrine cells or enterocytes. Live imaging of whole organs ex vivo reveals that stem-cell daughters adopt strikingly distinct patterns of Ca2+ oscillations after differentiation: enteroendocrine cells exhibit single-cell Ca2+ oscillations, whereas enterocytes exhibit rhythmic, long-range Ca2+ waves. These multicellular waves do not propagate through immature progenitors (stem cells and enteroblasts), of which the oscillation frequency is approximately half that of enteroendocrine cells. Organ-scale inhibition of gap junctions eliminates Ca2+ oscillations in all cell types - even, intriguingly, in progenitor and enteroendocrine cells that are surrounded only by enterocytes. Our findings establish that cells adopt fate-specific modes of Ca2+ dynamics as they terminally differentiate and reveal that the oscillatory dynamics of different cell types in a single, coherent epithelium are paced independently.
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Affiliation(s)
- Anna A Kim
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Materials Science and Engineering, Uppsala University, 75103 Uppsala, Sweden
| | - Amanda Nguyen
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Marco Marchetti
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - XinXin Du
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Denise J Montell
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Beth L Pruitt
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Lucy Erin O'Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Chan-Zuckerberg Biohub, San Francisco, CA 94158, USA
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20
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Hutchings DC, Madders GWP, Niort BC, Bode EF, Waddell CA, Woods LS, Dibb KM, Eisner DA, Trafford AW. Interaction of background Ca 2+ influx, sarcoplasmic reticulum threshold and heart failure in determining propensity for Ca 2+ waves in sheep heart. J Physiol 2022; 600:2637-2650. [PMID: 35233776 PMCID: PMC9310721 DOI: 10.1113/jp282168] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/25/2022] [Indexed: 11/11/2022] Open
Abstract
Ventricular arrhythmias can cause death in heart failure (HF). A trigger is the occurrence of Ca2+ waves which activate a Na+ -Ca2+ exchange (NCX) current, leading to delayed after-depolarisations and triggered action potentials. Waves arise when sarcoplasmic reticulum (SR) Ca2+ content reaches a threshold and are commonly induced experimentally by raising external Ca2+ , although the mechanism by which this causes waves is unclear and was the focus of this study. Intracellular Ca2+ was measured in voltage-clamped ventricular myocytes from both control sheep and those subjected to rapid pacing to produce HF. Threshold SR Ca2+ content was determined by applying caffeine (10 mM) following a wave and integrating wave and caffeine-induced NCX currents. Raising external Ca2+ induced waves in a greater proportion of HF cells than control. The associated increase of SR Ca2+ content was smaller in HF due to a lower threshold. Raising external Ca2+ had no effect on total influx via the L-type Ca2+ current, ICa-L , and increased efflux on NCX. Analysis of sarcolemmal fluxes revealed substantial background Ca2+ entry which sustains Ca2+ efflux during waves in the steady state. Wave frequency and background Ca2+ entry were decreased by Gd3+ or the TRPC6 inhibitor BI 749327. These agents also blocked Mn2+ entry. Inhibiting connexin hemi-channels, TRPC1/4/5, L-type channels or NCX had no effect on background entry. In conclusion, raising external Ca2+ induces waves via a background Ca2+ influx through TRPC6 channels. The greater propensity to waves in HF results from increased background entry and decreased threshold SR content. KEY POINTS: Heart failure is a pro-arrhythmic state and arrhythmias are a major cause of death. At the cellular level, Ca2+ waves resulting in delayed after-depolarisations are a key trigger of arrhythmias. Ca2+ waves arise when the sarcoplasmic reticulum (SR) becomes overloaded with Ca2+ . We investigate the mechanism by which raising external Ca2+ causes waves, and how this is modified in heart failure. We demonstrate that a novel sarcolemmal background Ca2+ influx via the TRPC6 channel is responsible for SR Ca2+ overload and Ca2+ waves. The increased propensity for Ca2+ waves in heart failure results from an increase of background influx, and a lower threshold SR content. The results of the present study highlight a novel mechanism by which Ca2+ waves may arise in heart failure, providing a basis for future work and novel therapeutic targets.
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Affiliation(s)
- David C Hutchings
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK.,Manchester University NHS Foundation Trust, Manchester, UK
| | - George W P Madders
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Barbara C Niort
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Elizabeth F Bode
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Caitlin A Waddell
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Lori S Woods
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - David A Eisner
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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21
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New open-source software for subcellular segmentation and analysis of spatiotemporal fluorescence signals using deep learning. iScience 2022; 25:104277. [PMID: 35573197 PMCID: PMC9095751 DOI: 10.1016/j.isci.2022.104277] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/04/2022] [Accepted: 04/18/2022] [Indexed: 11/20/2022] Open
Abstract
Cellular imaging instrumentation advancements as well as readily available optogenetic and fluorescence sensors have yielded a profound need for fast, accurate, and standardized analysis. Deep-learning architectures have revolutionized the field of biomedical image analysis and have achieved state-of-the-art accuracy. Despite these advancements, deep learning architectures for the segmentation of subcellular fluorescence signals is lacking. Cellular dynamic fluorescence signals can be plotted and visualized using spatiotemporal maps (STMaps), and currently their segmentation and quantification are hindered by slow workflow speed and lack of accuracy, especially for large datasets. In this study, we provide a software tool that utilizes a deep-learning methodology to fundamentally overcome signal segmentation challenges. The software framework demonstrates highly optimized and accurate calcium signal segmentation and provides a fast analysis pipeline that can accommodate different patterns of signals across multiple cell types. The software allows seamless data accessibility, quantification, and graphical visualization and enables large dataset analysis throughput. 4SM: an automated software solution for cellular dynamic fluorescence signal analysis 4SM relies on a novel machine-learning pipeline for fluorescence signal segmentation 4SM is fast and provides a consistent method for high-throughput analysis of datasets 4SM provides instant signal quantification and graphical representation of the results
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22
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Nolla‐Colomer C, Casabella‐Ramon S, Jimenez‐Sabado V, Vallmitjana A, Tarifa C, Herraiz‐Martínez A, Llach A, Tauron M, Montiel J, Cinca J, Chen SRW, Benitez R, Hove‐Madsen L. β2-adrenergic stimulation potentiates spontaneous calcium release by increasing signal mass and co-activation of ryanodine receptor clusters. Acta Physiol (Oxf) 2022; 234:e13736. [PMID: 34709723 DOI: 10.1111/apha.13736] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 01/18/2023]
Abstract
AIMS It is unknown how β-adrenergic stimulation affects calcium dynamics in individual RyR2 clusters and leads to the induction of spontaneous calcium waves. To address this, we analysed spontaneous calcium release events in green fluorescent protein (GFP)-tagged RyR2 clusters. METHODS Cardiomyocytes from mice with GFP-tagged RyR2 or human right atrial tissue were subjected to immunofluorescent labelling or confocal calcium imaging. RESULTS Spontaneous calcium release from single RyR2 clusters induced 91.4% ± 2.0% of all calcium sparks while 8.0% ± 1.6% were caused by release from two neighbouring clusters. Sparks with two RyR2 clusters had 40% bigger amplitude, were 26% wider, and lasted 35% longer at half maximum. Consequently, the spark mass was larger in two- than one-cluster sparks with a median and interquartile range for the cumulative distribution of 15.7 ± 20.1 vs 7.6 ± 5.7 a.u. (P < .01). β2-adrenergic stimulation increased RyR2 phosphorylation at s2809 and s2815, tripled the fraction of two- and three-cluster sparks, and significantly increased the spark mass. Interestingly, the amplitude and mass of the calcium released from a RyR2 cluster were proportional to the SR calcium load, but the firing rate was not. The spark mass was also higher in 33 patients with atrial fibrillation than in 36 without (22.9 ± 23.4 a.u. vs 10.7 ± 10.9; P = .015). CONCLUSIONS Most sparks are caused by activation of a single RyR2 cluster at baseline while β-adrenergic stimulation doubles the mass and the number of clusters per spark. This mimics the shift in the cumulative spark mass distribution observed in myocytes from patients with atrial fibrillation.
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Affiliation(s)
| | - Sergi Casabella‐Ramon
- Biomedical Research Institute Barcelona, IIBB‐CSIC Barcelona Spain
- IIB Sant Pau Barcelona Spain
| | | | | | - Carmen Tarifa
- Biomedical Research Institute Barcelona, IIBB‐CSIC Barcelona Spain
- IIB Sant Pau Barcelona Spain
| | - Adela Herraiz‐Martínez
- Biomedical Research Institute Barcelona, IIBB‐CSIC Barcelona Spain
- IIB Sant Pau Barcelona Spain
| | | | - Manel Tauron
- Department of Cardiac Surgery Hospital de la Santa Creu i Sant Pau Barcelona Spain
| | - Jose Montiel
- Department of Cardiac Surgery Hospital de la Santa Creu i Sant Pau Barcelona Spain
| | - Juan Cinca
- IIB Sant Pau Barcelona Spain
- Universitat Autònoma de Barcelona Barcelona Spain
| | - S. R. Wayne Chen
- Department of Physiology and Pharmacology University of Calgary Alberta Canada
| | - Raul Benitez
- Department Automatic Control Univ. Politècnica de Catalunya Barcelona Spain
| | - Leif Hove‐Madsen
- Biomedical Research Institute Barcelona, IIBB‐CSIC Barcelona Spain
- IIB Sant Pau Barcelona Spain
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23
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de Zélicourt A, Fayssoil A, Dakouane-Giudicelli M, De Jesus I, Karoui A, Zarrouki F, Lefebvre F, Mansart A, Launay JM, Piquereau J, Tarragó MG, Bonay M, Forand A, Moog S, Piétri-Rouxel F, Brisebard E, Chini CCS, Kashyap S, Fogarty MJ, Sieck GC, Mericskay M, Chini EN, Gomez AM, Cancela JM, de la Porte S. CD38-NADase is a new major contributor to Duchenne muscular dystrophic phenotype. EMBO Mol Med 2022; 14:e12860. [PMID: 35298089 PMCID: PMC9081905 DOI: 10.15252/emmm.202012860] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 01/14/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration. Two important deleterious features are a Ca2+ dysregulation linked to Ca2+ influxes associated with ryanodine receptor hyperactivation, and a muscular nicotinamide adenine dinucleotide (NAD+) deficit. Here, we identified that deletion in mdx mice of CD38, a NAD+ glycohydrolase‐producing modulators of Ca2+ signaling, led to a fully restored heart function and structure, with skeletal muscle performance improvements, associated with a reduction in inflammation and senescence markers. Muscle NAD+ levels were also fully restored, while the levels of the two main products of CD38, nicotinamide and ADP‐ribose, were reduced, in heart, diaphragm, and limb. In cardiomyocytes from mdx/CD38−/− mice, the pathological spontaneous Ca2+ activity was reduced, as well as in myotubes from DMD patients treated with isatuximab (SARCLISA®) a monoclonal anti‐CD38 antibody. Finally, treatment of mdx and utrophin–dystrophin‐deficient (mdx/utr−/−) mice with CD38 inhibitors resulted in improved skeletal muscle performances. Thus, we demonstrate that CD38 actively contributes to DMD physiopathology. We propose that a selective anti‐CD38 therapeutic intervention could be highly relevant to develop for DMD patients.
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Affiliation(s)
- Antoine de Zélicourt
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, Versailles, France.,Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, Saclay, France
| | | | | | - Isley De Jesus
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, Versailles, France
| | - Ahmed Karoui
- Signalisation et Physiopathologie Cardiovasculaire, INSERM, UMR-S 1180 - Université Paris-Saclay, Châtenay-Malabry, France
| | - Faouzi Zarrouki
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, Versailles, France
| | - Florence Lefebvre
- Signalisation et Physiopathologie Cardiovasculaire, INSERM, UMR-S 1180 - Université Paris-Saclay, Châtenay-Malabry, France
| | - Arnaud Mansart
- Université Paris-Saclay, UVSQ, Inserm, 2I, Versailles, France
| | - Jean-Marie Launay
- Service de Biochimie, INSERM UMR S942, Hôpital Lariboisière, Paris, France
| | - Jerome Piquereau
- Signalisation et Physiopathologie Cardiovasculaire, INSERM, UMR-S 1180 - Université Paris-Saclay, Châtenay-Malabry, France
| | - Mariana G Tarragó
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Marcel Bonay
- Université Paris-Saclay, UVSQ, Inserm, END-ICAP, Versailles, France
| | - Anne Forand
- Centre de Recherche en Myologie, Faculté de Médecine de la Pitié Salpêtrière, Sorbonne Université-UMRS974-Inserm-Institut de Myologie, Paris, France.,Inovarion, Paris, France
| | - Sophie Moog
- Centre de Recherche en Myologie, Faculté de Médecine de la Pitié Salpêtrière, Sorbonne Université-UMRS974-Inserm-Institut de Myologie, Paris, France.,Inovarion, Paris, France
| | - France Piétri-Rouxel
- Centre de Recherche en Myologie, Faculté de Médecine de la Pitié Salpêtrière, Sorbonne Université-UMRS974-Inserm-Institut de Myologie, Paris, France
| | | | - Claudia C S Chini
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Sonu Kashyap
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Matthew J Fogarty
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Gary C Sieck
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Mathias Mericskay
- Signalisation et Physiopathologie Cardiovasculaire, INSERM, UMR-S 1180 - Université Paris-Saclay, Châtenay-Malabry, France
| | - Eduardo N Chini
- Department of Anesthesiology and Kogod Aging Center, Mayo Clinic, Rochester, Minnesota, USA
| | - Ana Maria Gomez
- Signalisation et Physiopathologie Cardiovasculaire, INSERM, UMR-S 1180 - Université Paris-Saclay, Châtenay-Malabry, France
| | - José-Manuel Cancela
- Institut des Neurosciences Paris-Saclay, CNRS, Université Paris-Saclay, Saclay, France
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24
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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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25
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Huang DX, Yu X, Yu WJ, Zhang XM, Liu C, Liu HP, Sun Y, Jiang ZP. Calcium Signaling Regulated by Cellular Membrane Systems and Calcium Homeostasis Perturbed in Alzheimer’s Disease. Front Cell Dev Biol 2022; 10:834962. [PMID: 35281104 PMCID: PMC8913592 DOI: 10.3389/fcell.2022.834962] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/31/2022] [Indexed: 12/12/2022] Open
Abstract
Although anything that changes spatiotemporally could be a signal, cells, particularly neurons, precisely manipulate calcium ion (Ca2+) to transmit information. Ca2+ homeostasis is indispensable for neuronal functions and survival. The cytosolic Ca2+ concentration ([Ca2+]CYT) is regulated by channels, pumps, and exchangers on cellular membrane systems. Under physiological conditions, both endoplasmic reticulum (ER) and mitochondria function as intracellular Ca2+ buffers. Furthermore, efficient and effective Ca2+ flux is observed at the ER-mitochondria membrane contact site (ERMCS), an intracellular membrane juxtaposition, where Ca2+ is released from the ER followed by mitochondrial Ca2+ uptake in sequence. Hence, the ER intraluminal Ca2+ concentration ([Ca2+]ER), the mitochondrial matrix Ca2+ concentration ([Ca2+]MT), and the [Ca2+]CYT are related to each other. Ca2+ signaling dysregulation and Ca2+ dyshomeostasis are associated with Alzheimer’s disease (AD), an irreversible neurodegenerative disease. The present review summarizes the cellular and molecular mechanism underlying Ca2+ signaling regulation and Ca2+ homeostasis maintenance at ER and mitochondria levels, focusing on AD. Integrating the amyloid hypothesis and the calcium hypothesis of AD may further our understanding of pathogenesis in neurodegeneration, provide therapeutic targets for chronic neurodegenerative disease in the central nervous system.
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Affiliation(s)
- Dong-Xu Huang
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Xin Yu
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Wen-Jun Yu
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
| | - Xin-Min Zhang
- Department of Anesthesiology, The First Hospital of Jilin University, Changchun, China
| | - Chang Liu
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Hong-Ping Liu
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Yue Sun
- Deparment of The First Operating Room, The First Hospital of Jilin University, Changchun, China
| | - Zi-Ping Jiang
- Department of Hand and Foot Surgery, The First Hospital of Jilin University, Changchun, China
- *Correspondence: Zi-Ping Jiang,
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26
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Cumberland MJ, Riebel LL, Roy A, O’Shea C, Holmes AP, Denning C, Kirchhof P, Rodriguez B, Gehmlich K. Basic Research Approaches to Evaluate Cardiac Arrhythmia in Heart Failure and Beyond. Front Physiol 2022; 13:806366. [PMID: 35197863 PMCID: PMC8859441 DOI: 10.3389/fphys.2022.806366] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/10/2022] [Indexed: 12/20/2022] Open
Abstract
Patients with heart failure often develop cardiac arrhythmias. The mechanisms and interrelations linking heart failure and arrhythmias are not fully understood. Historically, research into arrhythmias has been performed on affected individuals or in vivo (animal) models. The latter however is constrained by interspecies variation, demands to reduce animal experiments and cost. Recent developments in in vitro induced pluripotent stem cell technology and in silico modelling have expanded the number of models available for the evaluation of heart failure and arrhythmia. An agnostic approach, combining the modalities discussed here, has the potential to improve our understanding for appraising the pathology and interactions between heart failure and arrhythmia and can provide robust and validated outcomes in a variety of research settings. This review discusses the state of the art models, methodologies and techniques used in the evaluation of heart failure and arrhythmia and will highlight the benefits of using them in combination. Special consideration is paid to assessing the pivotal role calcium handling has in the development of heart failure and arrhythmia.
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Affiliation(s)
- Max J. Cumberland
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Leto L. Riebel
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Ashwin Roy
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Christopher O’Shea
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew P. Holmes
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Chris Denning
- Stem Cell Biology Unit, Biodiscovery Institute, British Heart Foundation Centre for Regenerative Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- University Heart and Vascular Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford and British Heart Foundation Centre of Research Excellence Oxford, Oxford, United Kingdom
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27
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Sato H, Nagano T, Satoh W, Kumasaka K, Shindoh C, Miura M. Roles of stretch-activated channels and NADPH oxidase 2 in the induction of twitch contraction by muscle stretching in rat ventricular muscle. Pflugers Arch 2022; 474:355-363. [PMID: 35066611 DOI: 10.1007/s00424-021-02657-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/28/2022]
Abstract
Mechano-electric feedback means that muscle stretching causes depolarization of membrane potential. We investigated whether muscle stretching induces action potential and twitch contraction with a threshold of sarcomere length (SL) and what roles stretch-activated channels (SACs) and stretch-activated NADPH oxidase (X-ROS signaling) play in the induction. Trabeculae were obtained from the right ventricles of rat hearts. Force, SL, and [Ca2+]i were measured. Various degrees of stretching from the SL of 2.0 μm were applied 0.5 s after the last stimulus of the electrical train with 0.4-s intervals for 7.5 s. The SLtwitch was defined as the minimal SL at which twitch contraction was induced by the stretching. Muscle stretching induced twitch contraction with a threshold of SL at 0.4-s stimulus intervals ([Ca2+]o = 0.7 mmol/L). The SLtwitch was not changed by increasing the stimulus intervals and [Ca2+]o and by adding 1 μmol/L isoproterenol. The SLtwitch was not changed by adding 10 μmol/L Gd3+, 100 μmol/L or 200 μmol/L streptomycin, and 5 μmol/L GsMTx4. The SLtwitch was not changed by adding 1 μmol/L ryanodine and 3 μmol/L diphenyleneiodonium chloride. In contrast, the SLtwitch was increased by elevating extracellular K+ from 5 to 10 mmol/L and by adding the stretching during the refractory period of membrane potential. The addition of the stretching-induced twitch contraction more frequently induced arrhythmias. These results suggest that muscle stretching can induce twitch contraction with a threshold of SL and concern the occurrence of arrhythmias and that SACs and X-ROS signaling play no roles in the induction.
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Affiliation(s)
- Haruka Sato
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Tsuyoshi Nagano
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Wakako Satoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Kazunori Kumasaka
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Chiyohiko Shindoh
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan.
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28
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Ca 2+ mishandling and mitochondrial dysfunction: a converging road to prediabetic and diabetic cardiomyopathy. Pflugers Arch 2022; 474:33-61. [PMID: 34978597 PMCID: PMC8721633 DOI: 10.1007/s00424-021-02650-y] [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: 05/24/2021] [Revised: 11/17/2021] [Accepted: 12/03/2021] [Indexed: 12/16/2022]
Abstract
Diabetic cardiomyopathy is defined as the myocardial dysfunction that suffers patients with diabetes mellitus (DM) in the absence of hypertension and structural heart diseases such as valvular or coronary artery dysfunctions. Since the impact of DM on cardiac function is rather silent and slow, early stages of diabetic cardiomyopathy, known as prediabetes, are poorly recognized, and, on many occasions, cardiac illness is diagnosed only after a severe degree of dysfunction was reached. Therefore, exploration and recognition of the initial pathophysiological mechanisms that lead to cardiac dysfunction in diabetic cardiomyopathy are of vital importance for an on-time diagnosis and treatment of the malady. Among the complex and intricate mechanisms involved in diabetic cardiomyopathy, Ca2+ mishandling and mitochondrial dysfunction have been described as pivotal early processes. In the present review, we will focus on these two processes and the molecular pathway that relates these two alterations to the earlier stages and the development of diabetic cardiomyopathy.
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29
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Hoang-Trong TM, Ullah A, Lederer WJ, Jafri MS. A Stochastic Spatiotemporal Model of Rat Ventricular Myocyte Calcium Dynamics Demonstrated Necessary Features for Calcium Wave Propagation. MEMBRANES 2021; 11:989. [PMID: 34940490 PMCID: PMC8706945 DOI: 10.3390/membranes11120989] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022]
Abstract
Calcium (Ca2+) plays a central role in the excitation and contraction of cardiac myocytes. Experiments have indicated that calcium release is stochastic and regulated locally suggesting the possibility of spatially heterogeneous calcium levels in the cells. This spatial heterogeneity might be important in mediating different signaling pathways. During more than 50 years of computational cell biology, the computational models have been advanced to incorporate more ionic currents, going from deterministic models to stochastic models. While periodic increases in cytoplasmic Ca2+ concentration drive cardiac contraction, aberrant Ca2+ release can underly cardiac arrhythmia. However, the study of the spatial role of calcium ions has been limited due to the computational expense of using a three-dimensional stochastic computational model. In this paper, we introduce a three-dimensional stochastic computational model for rat ventricular myocytes at the whole-cell level that incorporate detailed calcium dynamics, with (1) non-uniform release site placement, (2) non-uniform membrane ionic currents and membrane buffers, (3) stochastic calcium-leak dynamics and (4) non-junctional or rogue ryanodine receptors. The model simulates spark-induced spark activation and spark-induced Ca2+ wave initiation and propagation that occur under conditions of calcium overload at the closed-cell condition, but not when Ca2+ levels are normal. This is considered important since the presence of Ca2+ waves contribute to the activation of arrhythmogenic currents.
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Affiliation(s)
- Tuan Minh Hoang-Trong
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA; (T.M.H.-T.); (A.U.)
| | - Aman Ullah
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA; (T.M.H.-T.); (A.U.)
| | - William Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Mohsin Saleet Jafri
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA; (T.M.H.-T.); (A.U.)
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
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30
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Pandey V, Xie LH, Qu Z, Song Z. Mitochondrial Contributions in the Genesis of Delayed Afterdepolarizations in Ventricular Myocytes. Front Physiol 2021; 12:744023. [PMID: 34721066 PMCID: PMC8551757 DOI: 10.3389/fphys.2021.744023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/02/2021] [Indexed: 11/17/2022] Open
Abstract
Mitochondria fulfill the cell's energy demand and affect the intracellular calcium (Ca2+) dynamics via direct Ca2+ exchange, the redox effect of reactive oxygen species (ROS) on Ca2+ handling proteins, and other signaling pathways. Recent experimental evidence indicates that mitochondrial depolarization promotes arrhythmogenic delayed afterdepolarizations (DADs) in cardiac myocytes. However, the nonlinear interactions among the Ca2+ signaling pathways, ROS, and oxidized Ca2+/calmodulin-dependent protein kinase II (CaMKII) pathways make it difficult to reveal the mechanisms. Here, we use a recently developed spatiotemporal ventricular myocyte computer model, which consists of a 3-dimensional network of Ca2+ release units (CRUs) intertwined with mitochondria and integrates mitochondrial Ca2+ signaling and other complex signaling pathways, to study the mitochondrial regulation of DADs. With a systematic investigation of the synergistic or competing factors that affect the occurrence of Ca2+ waves and DADs during mitochondrial depolarization, we find that the direct redox effect of ROS on ryanodine receptors (RyRs) plays a critical role in promoting Ca2+ waves and DADs under the acute effect of mitochondrial depolarization. Furthermore, the upregulation of mitochondrial Ca2+ uniporter can promote DADs through Ca2+-dependent opening of mitochondrial permeability transition pores (mPTPs). Also, due to much slower dynamics than Ca2+ cycling and ROS, oxidized CaMKII activation and the cytosolic ATP do not appear to significantly impact the genesis of DADs during the acute phase of mitochondrial depolarization. However, under chronic conditions, ATP depletion suppresses and enhanced CaMKII activation promotes Ca2+ waves and DADs.
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Affiliation(s)
- Vikas Pandey
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Peng Cheng Laboratory, Shenzhen, China
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31
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Benitah JP, Perrier R, Mercadier JJ, Pereira L, Gómez AM. RyR2 and Calcium Release in Heart Failure. Front Physiol 2021; 12:734210. [PMID: 34690808 PMCID: PMC8533677 DOI: 10.3389/fphys.2021.734210] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/30/2021] [Indexed: 12/24/2022] Open
Abstract
Heart Failure (HF) is defined as the inability of the heart to efficiently pump out enough blood to maintain the body's needs, first at exercise and then also at rest. Alterations in Ca2+ handling contributes to the diminished contraction and relaxation of the failing heart. While most Ca2+ handling protein expression and/or function has been shown to be altered in many models of experimental HF, in this review, we focus in the sarcoplasmic reticulum (SR) Ca2+ release channel, the type 2 ryanodine receptor (RyR2). Various modifications of this channel inducing alterations in its function have been reported. The first was the fact that RyR2 is less responsive to activation by Ca2+ entry through the L-Type calcium channel, which is the functional result of an ultrastructural remodeling of the ventricular cardiomyocyte, with fewer and disorganized transverse (T) tubules. HF is associated with an elevated sympathetic tone and in an oxidant environment. In this line, enhanced RyR2 phosphorylation and oxidation have been shown in human and experimental HF. After several controversies, it is now generally accepted that phosphorylation of RyR2 at the Calmodulin Kinase II site (S2814) is involved in both the depressed contractile function and the enhanced arrhythmic susceptibility of the failing heart. Diminished expression of the FK506 binding protein, FKBP12.6, may also contribute. While these alterations have been mostly studied in the left ventricle of HF with reduced ejection fraction, recent studies are looking at HF with preserved ejection fraction. Moreover, alterations in the RyR2 in HF may also contribute to supraventricular defects associated with HF such as sinus node dysfunction and atrial fibrillation.
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Affiliation(s)
| | | | | | | | - Ana M. Gómez
- Signaling and Cardiovascular Pathophysiology—UMR-S 1180, INSERM, Université Paris-Saclay, Châtenay-Malabry, France
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Setterberg IE, Le C, Frisk M, Li J, Louch WE. The Physiology and Pathophysiology of T-Tubules in the Heart. Front Physiol 2021; 12:718404. [PMID: 34566684 PMCID: PMC8458775 DOI: 10.3389/fphys.2021.718404] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/07/2021] [Indexed: 12/18/2022] Open
Abstract
In cardiomyocytes, invaginations of the sarcolemmal membrane called t-tubules are critically important for triggering contraction by excitation-contraction (EC) coupling. These structures form functional junctions with the sarcoplasmic reticulum (SR), and thereby enable close contact between L-type Ca2+ channels (LTCCs) and Ryanodine Receptors (RyRs). This arrangement in turn ensures efficient triggering of Ca2+ release, and contraction. While new data indicate that t-tubules are capable of exhibiting compensatory remodeling, they are also widely reported to be structurally and functionally compromised during disease, resulting in disrupted Ca2+ homeostasis, impaired systolic and/or diastolic function, and arrhythmogenesis. This review summarizes these findings, while highlighting an emerging appreciation of the distinct roles of t-tubules in the pathophysiology of heart failure with reduced and preserved ejection fraction (HFrEF and HFpEF). In this context, we review current understanding of the processes underlying t-tubule growth, maintenance, and degradation, underscoring the involvement of a variety of regulatory proteins, including junctophilin-2 (JPH2), amphiphysin-2 (BIN1), caveolin-3 (Cav3), and newer candidate proteins. Upstream regulation of t-tubule structure/function by cardiac workload and specifically ventricular wall stress is also discussed, alongside perspectives for novel strategies which may therapeutically target these mechanisms.
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Affiliation(s)
- Ingunn E Setterberg
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Christopher Le
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jia Li
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
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Lotteau S, Zhang R, Hazan A, Grabar C, Gonzalez D, Aynaszyan S, Philipson KD, Ottolia M, Goldhaber JI. Acute Genetic Ablation of Cardiac Sodium/Calcium Exchange in Adult Mice: Implications for Cardiomyocyte Calcium Regulation, Cardioprotection, and Arrhythmia. J Am Heart Assoc 2021; 10:e019273. [PMID: 34472363 PMCID: PMC8649274 DOI: 10.1161/jaha.120.019273] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Sodium‐calcium (Ca2+) exchanger isoform 1 (NCX1) is the dominant Ca2+ efflux mechanism in cardiomyocytes and is critical to maintaining Ca2+ homeostasis during excitation‐contraction coupling. NCX1 activity has been implicated in the pathogenesis of cardiovascular diseases, but a lack of specific NCX1 blockers complicates experimental interpretation. Our aim was to develop a tamoxifen‐inducible NCX1 knockout (KO) mouse to investigate compensatory adaptations of acute ablation of NCX1 on excitation‐contraction coupling and intracellular Ca2+ regulation, and to examine whether acute KO of NCX1 confers resistance to triggered arrhythmia and ischemia/reperfusion injury. Methods and Results We used the α‐myosin heavy chain promoter (Myh6)‐MerCreMer promoter to create a tamoxifen‐inducible cardiac‐specific NCX1 KO mouse. Within 1 week of tamoxifen injection, NCX1 protein expression and current were dramatically reduced. Diastolic Ca2+ increased despite adaptive reductions in Ca2+ current and action potential duration and compensatory increases in excitation‐contraction coupling gain, sarcoplasmic reticulum Ca2+ ATPase 2 and plasma membrane Ca2+ ATPase. As these adaptations progressed over 4 weeks, diastolic Ca2+ normalized and SR Ca2+ load increased. Left ventricular function remained normal, but mild fibrosis and hypertrophy developed. Transcriptomics revealed modification of cardiovascular‐related gene networks including cell growth and fibrosis. NCX1 KO reduced spontaneous action potentials triggered by delayed afterdepolarizations and reduced scar size in response to ischemia/reperfusion. Conclusions Tamoxifen‐inducible NCX1 KO mice adapt to acute genetic ablation of NCX1 by reducing Ca2+ influx, increasing alternative Ca2+ efflux pathways, and increasing excitation‐contraction coupling gain to maintain contractility at the cost of mild Ca2+‐activated hypertrophy and fibrosis and decreased survival. Nevertheless, KO myocytes are protected against spontaneous action potentials and ischemia/reperfusion injury.
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Affiliation(s)
- Sabine Lotteau
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Rui Zhang
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Adina Hazan
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Christina Grabar
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Devina Gonzalez
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | | | - Kenneth D Philipson
- Department of Physiology David Geffen School of Medicine at UCLA Los Angeles CA
| | - Michela Ottolia
- Division of Molecular Medicine Department of Anesthesiology and Perioperative Medicine David Geffen School of Medicine at UCLA Los Angeles CA
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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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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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36
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Mechanisms and Regulation of Cardiac Ca V1.2 Trafficking. Int J Mol Sci 2021; 22:ijms22115927. [PMID: 34072954 PMCID: PMC8197997 DOI: 10.3390/ijms22115927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/28/2021] [Accepted: 05/29/2021] [Indexed: 01/05/2023] Open
Abstract
During cardiac excitation contraction coupling, the arrival of an action potential at the ventricular myocardium triggers voltage-dependent L-type Ca2+ (CaV1.2) channels in individual myocytes to open briefly. The level of this Ca2+ influx tunes the amplitude of Ca2+-induced Ca2+ release from ryanodine receptors (RyR2) on the junctional sarcoplasmic reticulum and thus the magnitude of the elevation in intracellular Ca2+ concentration and ultimately the downstream contraction. The number and activity of functional CaV1.2 channels at the t-tubule dyads dictates the amplitude of the Ca2+ influx. Trafficking of these channels and their auxiliary subunits to the cell surface is thus tightly controlled and regulated to ensure adequate sarcolemmal expression to sustain this critical process. To that end, recent discoveries have revealed the existence of internal reservoirs of preformed CaV1.2 channels that can be rapidly mobilized to enhance sarcolemmal expression in times of acute stress when hemodynamic and metabolic demand increases. In this review, we provide an overview of the current thinking on CaV1.2 channel trafficking dynamics in the heart. We highlight the numerous points of control including the biosynthetic pathway, the endosomal recycling pathway, ubiquitination, and lysosomal and proteasomal degradation pathways, and discuss the effects of β-adrenergic and angiotensin receptor signaling cascades on this process.
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37
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Ottolini M, Sonkusare SK. The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells. Compr Physiol 2021; 11:1831-1869. [PMID: 33792900 PMCID: PMC10388069 DOI: 10.1002/cphy.c200030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca2+ signals and Ca2+ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca2+ signal on arterial contractility depends on the type of Ca2+ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca2+ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca2+ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca2+ signals have already been confirmed, while further investigation is needed for other Ca2+ signals. This article focuses on endothelial and smooth muscle Ca2+ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca2+ entry pathways at the plasma membrane, Ca2+ release signals from the intracellular stores, the functional and physiological relevance of Ca2+ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca2+ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.
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Affiliation(s)
- Matteo Ottolini
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Swapnil K Sonkusare
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA.,Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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38
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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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Liu X, Pan Z. Store-Operated Calcium Entry in the Cardiovascular System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:303-333. [DOI: 10.1007/978-981-16-4254-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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40
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Timmermann V, McCulloch AD. Mechano-Electric Coupling and Arrhythmogenic Current Generation in a Computational Model of Coupled Myocytes. Front Physiol 2020; 11:519951. [PMID: 33362569 PMCID: PMC7758443 DOI: 10.3389/fphys.2020.519951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 11/10/2020] [Indexed: 11/25/2022] Open
Abstract
A wide range of arrhythmogenic phenotypes have been associated with heterogeneous mechanical dyskinesis. Pro-arrhythmic effects are often associated with dysregulated intra-cellular calcium handling, especially via the development of intra- and inter-cellular calcium waves. Experimental evidence suggests that mechanical strain can contribute to the generation and maintenance of these calcium waves via a variety of mechano-electric coupling mechanisms. Most model studies of mechano-electric coupling mechanisms have been focused on mechano-sensitive ion channels, even though experimental studies have shown that intra- and inter-cellular calcium waves triggered by mechanical perturbations are likely to be more prevalent pro-arrhythmic mechanisms in the diseased heart. A one-dimensional strongly coupled computational model of electromechanics in rabbit ventricular cardiomyocytes showed that specific myocyte stretch sequences can modulate the susceptibility threshold for delayed after-depolarizations. In simulations of mechanically-triggered calcium waves in cardiomyocytes coupled to fibroblasts, susceptibility to calcium wave propagation was reduced as the current through the gap junction caused current drain from the myocytes. In 1D multi-cellular arrays coupled via gap junctions, mechanically-induced waves may contribute to synchronizing arrhythmogenic calcium waves and after-depolarizations.
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Affiliation(s)
- Viviane Timmermann
- Simula Research Laboratory, Department of Computational Physiology, Fornebu, Norway
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, United States
| | - Andrew D. McCulloch
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, United States
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41
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Leigh WA, Del Valle G, Kamran SA, Drumm BT, Tavakkoli A, Sanders KM, Baker SA. A high throughput machine-learning driven analysis of Ca 2+ spatio-temporal maps. Cell Calcium 2020; 91:102260. [PMID: 32795721 PMCID: PMC7530121 DOI: 10.1016/j.ceca.2020.102260] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/24/2020] [Accepted: 07/24/2020] [Indexed: 12/31/2022]
Abstract
High-resolution Ca2+ imaging to study cellular Ca2+ behaviors has led to the creation of large datasets with a profound need for standardized and accurate analysis. To analyze these datasets, spatio-temporal maps (STMaps) that allow for 2D visualization of Ca2+ signals as a function of time and space are often used. Methods of STMap analysis rely on a highly arduous process of user defined segmentation and event-based data retrieval. These methods are often time consuming, lack accuracy, and are extremely variable between users. We designed a novel automated machine-learning based plugin for the analysis of Ca2+ STMaps (STMapAuto). The plugin includes optimized tools for Ca2+ signal preprocessing, automated segmentation, and automated extraction of key Ca2+ event information such as duration, spatial spread, frequency, propagation angle, and intensity in a variety of cell types including the Interstitial cells of Cajal (ICC). The plugin is fully implemented in Fiji and able to accurately detect and expeditiously quantify Ca2+ transient parameters from ICC. The plugin's speed of analysis of large-datasets was 197-fold faster than the commonly used single pixel-line method of analysis. The automated machine-learning based plugin described dramatically reduces opportunities for user error and provides a consistent method to allow high-throughput analysis of STMap datasets.
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Affiliation(s)
- Wesley A Leigh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Guillermo Del Valle
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Sharif Amit Kamran
- Department of Computer Science and Engineering, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Bernard T Drumm
- Department of Life & Health Science, Dundalk Institute of Technology, Co. Louth, Ireland
| | - Alireza Tavakkoli
- Department of Computer Science and Engineering, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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42
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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43
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Dissecting Cellular Mechanisms of Long-Chain Acylcarnitines-Driven Cardiotoxicity: Disturbance of Calcium Homeostasis, Activation of Ca 2+-Dependent Phospholipases, and Mitochondrial Energetics Collapse. Int J Mol Sci 2020; 21:ijms21207461. [PMID: 33050414 PMCID: PMC7589681 DOI: 10.3390/ijms21207461] [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: 09/07/2020] [Revised: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 01/16/2023] Open
Abstract
Long-chain acylcarnitines (LCAC) are implicated in ischemia-reperfusion (I/R)-induced myocardial injury and mitochondrial dysfunction. Yet, molecular mechanisms underlying involvement of LCAC in cardiac injury are not sufficiently studied. It is known that in cardiomyocytes, palmitoylcarnitine (PC) can induce cytosolic Ca2+ accumulation, implicating L-type calcium channels, Na+/Ca2+ exchanger, and Ca2+-release from sarcoplasmic reticulum (SR). Alternatively, PC can evoke dissipation of mitochondrial potential (ΔΨm) and mitochondrial permeability transition pore (mPTP). Here, to dissect the complex nature of PC action on Ca2+ homeostasis and oxidative phosphorylation (OXPHOS) in cardiomyocytes and mitochondria, the methods of fluorescent microscopy, perforated path-clamp, and mitochondrial assays were used. We found that LCAC in dose-dependent manner can evoke Ca2+-sparks and oscillations, long-living Ca2+ enriched microdomains, and, finally, Ca2+ overload leading to hypercontracture and cardiomyocyte death. Collectively, PC-driven cardiotoxicity involves: (I) redistribution of Ca2+ from SR to mitochondria with minimal contribution of external calcium influx; (II) irreversible inhibition of Krebs cycle and OXPHOS underlying limited mitochondrial Ca2+ buffering; (III) induction of mPTP reinforced by PC-calcium interplay; (IV) activation of Ca2+-dependent phospholipases cPLA2 and PLC. Based on the inhibitory analysis we may suggest that simultaneous inhibition of both phospholipases could be an effective strategy for protection against PC-mediated toxicity in cardiomyocytes.
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Maltsev AV, Kokoz YM. Cardiomyocytes generating spontaneous Ca2+-transients as tools for precise estimation of sarcoplasmic reticulum Ca2+ transport. Arch Biochem Biophys 2020; 693:108542. [DOI: 10.1016/j.abb.2020.108542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 07/19/2020] [Accepted: 08/07/2020] [Indexed: 01/05/2023]
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Marchena M, Echebarria B, Shiferaw Y, Alvarez-Lacalle E. Buffering and total calcium levels determine the presence of oscillatory regimes in cardiac cells. PLoS Comput Biol 2020; 16:e1007728. [PMID: 32970668 PMCID: PMC7537911 DOI: 10.1371/journal.pcbi.1007728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 10/06/2020] [Accepted: 07/07/2020] [Indexed: 12/16/2022] Open
Abstract
Calcium oscillations and waves induce depolarization in cardiac cells which are believed to cause life-threathening arrhythimas. In this work, we study the conditions for the appearance of calcium oscillations in both a detailed subcellular model of calcium dynamics and a minimal model that takes into account just the minimal ingredients of the calcium toolkit. To avoid the effects of homeostatic changes and the interaction with the action potential we consider the somewhat artificial condition of a cell without pacing and with no calcium exchange with the extracellular medium. Both the full subcellular model and the minimal model present the same scenarios depending on the calcium load: two stationary states, one with closed ryanodine receptors (RyR) and most calcium in the cell stored in the sarcoplasmic reticulum (SR), and another, with open RyRs and a depleted SR. In between, calcium oscillations may appear. The robustness of these oscillations is determined by the amount of calsequestrin (CSQ). The lack of this buffer in the SR enhances the appearance of oscillations. The minimal model allows us to relate the stability of the oscillating state to the nullcline structure of the system, and find that its range of existence is bounded by a homoclinic and a Hopf bifurcation, resulting in a sudden transition to the oscillatory regime as the cell calcium load is increased. Adding a small amount of noise to the RyR behavior increases the parameter region where oscillations appear and provides a gradual transition from the resting state to the oscillatory regime, as observed in the subcellular model and experimentally. In cardiac cells, calcium plays a very important role. An increase in calcium levels is the trigger used by the cell to initiate contraction. Besides, calcium modulates several transmembrane currents, affecting the cell transmembrane potential. Thus, dysregulations in calcium handling have been associated with the appearance of arrhythmias. Often, this dysregulation results in the appearance of periodic calcium waves or global oscillations, providing a pro-arrhythmic substrate. In this paper, we study the onset of calcium oscillations in cardiac cells using both a detailed subcellular model of calcium dynamics and a minimal model that takes into account the essential ingredients of the calcium toolkit. Both reproduce the main experimental results and link this behavior with the presence of different steady-state solutions and bifurcations that depend on the total amount of calcium in the cell and in the level of buffering present. We expect that this work will help to clarify the conditions under which calcium oscillations appear in cardiac myocytes and, therefore, will represent a step further in the understanding of the origin of cardiac arrhythmias.
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Affiliation(s)
- Miquel Marchena
- Departament de Física, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Blas Echebarria
- Departament de Física, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Yohannes Shiferaw
- Physics Department, California State University, Northridge, California 91330, USA
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Guo W, Sun B, Estillore JP, Wang R, Chen SRW. The central domain of cardiac ryanodine receptor governs channel activation, regulation, and stability. J Biol Chem 2020; 295:15622-15635. [PMID: 32878990 DOI: 10.1074/jbc.ra120.013512] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/25/2020] [Indexed: 11/06/2022] Open
Abstract
Structural analyses identified the central domain of ryanodine receptor (RyR) as a transducer converting conformational changes in the cytoplasmic platform to the RyR gate. The central domain is also a regulatory hub encompassing the Ca2+-, ATP-, and caffeine-binding sites. However, the role of the central domain in RyR activation and regulation has yet to be defined. Here, we mutated five residues that form the Ca2+ activation site and 10 residues with negatively charged or oxygen-containing side chains near the Ca2+ activation site. We also generated eight disease-associated mutations within the central domain of RyR2. We determined the effect of these mutations on Ca2+, ATP, and caffeine activation and Mg2+ inhibition of RyR2. Mutating the Ca2+ activation site markedly reduced the sensitivity of RyR2 to Ca2+ and caffeine activation. Unexpectedly, Ca2+ activation site mutation E3848A substantially enhanced the Ca2+-independent basal activity of RyR2, suggesting that E3848A may also affect the stability of the closed state of RyR2. Mutations in the Ca2+ activation site also abolished the effect of ATP/caffeine on the Ca2+-independent basal activity, suggesting that the Ca2+ activation site is also a critical determinant of ATP/caffeine action. Mutating residues with negatively charged or oxygen-containing side chains near the Ca2+ activation site significantly altered Ca2+ and caffeine activation and reduced Mg2+ inhibition. Furthermore, disease-associated RyR2 mutations within the central domain significantly enhanced Ca2+ and caffeine activation and reduced Mg2+ inhibition. Our data demonstrate that the central domain plays an important role in channel activation, channel regulation, and closed state stability.
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Affiliation(s)
- Wenting Guo
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - Bo Sun
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Medical School, Kunming University of Science and Technology, Kunming, China
| | - John Paul Estillore
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - S R Wayne Chen
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada.
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Li A, Zhou J, Widelitz RB, Chow RH, Chuong CM. Integrating Bioelectrical Currents and Ca 2+ Signaling with Biochemical Signaling in Development and Pathogenesis. Bioelectricity 2020; 2:210-220. [PMID: 34476353 PMCID: PMC8370337 DOI: 10.1089/bioe.2020.0001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Roles of bioelectrical signals are increasingly recognized in excitable and nonexcitable non-neural tissues. Diverse ion-selective channels, pumps, and gap junctions participate in bioelectrical signaling, including those transporting calcium ions (Ca2+). Ca2+ is the most versatile transported ion, because it serves as an electrical charge carrier and a biochemical regulator for multiple molecular binding, enzyme, and transcription activities. We aspire to learn how bioelectrical signals crosstalk to biochemical/biomechanical signals. In this study, we review four recent studies showing how bioelectrical currents and Ca2+ signaling affect collective dermal cell migration during feather bud elongation, affect chondrogenic differentiation in limb development, couple with mechanical tension in aligning gut smooth muscle, and affect mitochondrial function and skeletal muscle atrophy. We observe bioelectrical signals involved in several developmental and pathological conditions in chickens and mice at multiple spatial scales: cellular, cellular collective, and subcellular. These examples inspire novel concept and approaches for future basic and translational studies.
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Affiliation(s)
- Ang Li
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas, USA
| | - Jingsong Zhou
- Department of Kinesiology, College of Nursing and Health Innovation, University of Texas at Arlington, Arlington, Texas, USA
| | - Randall B. Widelitz
- Department of Pathology and Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Robert H. Chow
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Cheng-Ming Chuong
- Department of Pathology and Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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Lu F, Pu WT. The architecture and function of cardiac dyads. Biophys Rev 2020; 12:1007-1017. [PMID: 32661902 PMCID: PMC7429583 DOI: 10.1007/s12551-020-00729-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 07/03/2020] [Indexed: 12/28/2022] Open
Abstract
Cardiac excitation-contraction (EC) coupling, which links plasma membrane depolarization to activation of cardiomyocyte contraction, occurs at dyads, the nanoscopic microdomains formed by apposition of transverse (T)-tubules and junctional sarcoplasmic reticulum (jSR). In a dyadic junction, EC coupling occurs through Ca2+-induced Ca2+ release. Membrane depolarization opens voltage-gated L-type Ca2+ channels (LTCCs) in the T-tubule. The resulting influx of extracellular Ca2+ into the dyadic cleft opens Ca2+ release channels known as ryanodine receptors (RYRs) in the jSR, leading to the rapid increase in cytosolic Ca2+ that triggers sarcomere contraction. The efficacy of LTCC-RYR communication greatly affects a myriad of downstream intracellular signaling events, and it is controlled by many factors, including T-tubule and jSR structure, spatial distribution of ion channels, and regulatory proteins that closely regulate the activities of channels within dyads. Alterations in dyad architecture and/or channel activity are seen in many types of heart disease. This review will focus on the current knowledge regarding cardiac dyad structure and function, their alterations in heart failure, and new approaches to study the composition and function of dyads.
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Affiliation(s)
- Fujian Lu
- Department of Cardiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, 02115, USA
| | - William T Pu
- Department of Cardiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA, 02115, USA.
- Harvard Stem Cell Institute, 7 Divinity Avenue, Cambridge, MA, 02138, USA.
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Intracellular calcium leak in heart failure and atrial fibrillation: a unifying mechanism and therapeutic target. Nat Rev Cardiol 2020; 17:732-747. [PMID: 32555383 DOI: 10.1038/s41569-020-0394-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/06/2020] [Indexed: 12/14/2022]
Abstract
Ca2+ is a fundamental second messenger in all cell types and is required for numerous essential cellular functions, including cardiac and skeletal muscle contraction. The intracellular concentration of free Ca2+ ([Ca2+]) is regulated primarily by ion channels, pumps (ATPases), exchangers and Ca2+-binding proteins. Defective regulation of [Ca2+] is found in a diverse spectrum of pathological states that affect all the major organs. In the heart, abnormalities in the regulation of cytosolic and mitochondrial [Ca2+] occur in heart failure (HF) and atrial fibrillation (AF), two common forms of heart disease and leading contributors to morbidity and mortality. In this Review, we focus on the mechanisms that regulate ryanodine receptor 2 (RYR2), the major sarcoplasmic reticulum (SR) Ca2+-release channel in the heart, how RYR2 becomes dysfunctional in HF and AF, and its potential as a therapeutic target. Inherited RYR2 mutations and/or stress-induced phosphorylation and oxidation of the protein destabilize the closed state of the channel, resulting in a pathological diastolic Ca2+ leak from the SR that both triggers arrhythmias and impairs contractility. On the basis of our increased understanding of SR Ca2+ leak as a shared Ca2+-dependent pathological mechanism in HF and AF, a new class of drugs developed in our laboratory, known as rycals, which stabilize RYR2 channels and prevent Ca2+ leak from the SR, are undergoing investigation in clinical trials.
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Martinez-Hernandez E, Blatter LA. Effect of carvedilol on atrial excitation-contraction coupling, Ca 2+ release, and arrhythmogenicity. Am J Physiol Heart Circ Physiol 2020; 318:H1245-H1255. [PMID: 32275472 DOI: 10.1152/ajpheart.00650.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Carvedilol is an FDA-approved β-blocker commonly used for treatment of high blood pressure, congestive heart failure, and cardiac tachyarrhythmias, including atrial fibrillation. We investigated at the cellular level the mechanisms through which carvedilol interferes with sarcoplasmic reticulum (SR) Ca2+ release during excitation-contraction coupling (ECC) in single rabbit atrial myocytes. Carvedilol caused concentration-dependent (1-10 µM) failure of SR Ca2+ release. Failure of ECC and Ca2+ release was the result of dose-dependent inhibition of voltage-gated Na+ (INa) and L-type Ca2+ (ICa) currents that are responsible for the rapid depolarization phase of the cardiac action potential (AP) and the initiation of Ca2+-induced Ca2+ release from the SR, respectively. Carvedilol (1 µM) led to AP duration shortening, AP failures, and peak INa inhibition by ~80%, whereas ICa was not markedly affected. Carvedilol (10 µM) blocked INa almost completely and reduced ICa by ~40%. No effect on Ca2+-transient amplitude, ICa, and INa was observed in control experiments with the β-blocker metoprolol, suggesting that the carvedilol effect on ECC is unlikely the result of its β-blocking property. The effects of carvedilol (1 µM) on subcellular SR Ca2+ release was spatially inhomogeneous, where a selective inhibition of peripheral subsarcolemmal Ca2+ release from the junctional SR accounted for the cell-averaged reduction in Ca2+-transient amplitude. Furthermore, carvedilol significantly reduced the probability of spontaneous arrhythmogenic Ca2+ waves without changes of SR Ca2+ load. The data suggest a profound antiarrhythmic action of carvedilol in atrial myocytes resulting from an inhibitory effect on the SR Ca2+ release channel.NEW & NOTEWORTHY Here we show that the clinically widely used β-blocker carvedilol has profound effects on Ca2+ signaling and ion currents, but also antiarrhythmic effects in adult atrial myocytes. Carvedilol inhibits sodium and calcium currents and leads to failure of ECC but also prevents spontaneous Ca2+ release from cellular sarcoplasmic reticulum (SR) Ca2+ stores in form of arrhythmogenic Ca2+ waves. The antiarrhythmic effect occurs by carvedilol acting directly on the SR ryanodine receptor Ca2+ release channel.
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Affiliation(s)
- E Martinez-Hernandez
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois
| | - L A Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois
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