1
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Fernández-Morales JC, Toth N, Bayram P, Rienzo T, Morad M. Loss-of-function W4645R mutation in the RyR2-caffeine binding site: implications for synchrony and arrhythmogenesis. Cell Calcium 2024; 123:102925. [PMID: 38908063 PMCID: PMC11392648 DOI: 10.1016/j.ceca.2024.102925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 06/24/2024]
Abstract
AIMS Previous studies have identified RyR2 W4645R mutation, located in the caffeine-binding site, to associate with CPVT1 pathology. Caffeine binding to its site is thought to displace the carboxyl-terminal domain to Ca2+-binding, allowing the tryptophan residue (W4645) to regulate Ca2+ sensitivity of RyR2. To gain insights into regulation of RyR2 Ca2+-binding and its interaction with caffeine-binding site, we introduced W4645R-RyR2 point mutation via CRISPR/Cas9 gene-editing in human induced pluripotent stem cell-derived cardiomyocytes (hiPSCCMs) and characterized their Ca2+-signaling phenotype compared to WT hiPSCCMs. METHODS AND RESULTS W4645R-RyR2 cardiomyocytes had: (1) no significant change in ICa magnitude or voltage-dependence; (2) slightly reduced CICR; (3) altered relaxation kinetics of Ca2+-transients with no change in isoproterenol sensitivity; (4) complete loss of caffeine-triggered Ca2+ release; (5) larger SR Ca2+ leak resulting in 40 % lower SR Ca2+ content, as determined by myocytes' response to 4-CmC; (6) lower incidence of calcium sparks and asynchronous spontaneous SR Ca2+ releases. CONCLUSIONS W4645R-RyR2 mutation induces loss of caffeine-triggered SR Ca2+ release and enhances SR Ca2+ leak that underlie asynchronous spontaneous Ca2+ releases, triggering arrhythmia and impairing cardiac function.
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Affiliation(s)
| | - Noemi Toth
- Cardiac Signaling Center of MUSC, USC and Clemson University, Charleston, SC, USA
| | - Pinar Bayram
- Cardiac Signaling Center of MUSC, USC and Clemson University, Charleston, SC, USA
| | - Taylor Rienzo
- Cardiac Signaling Center of MUSC, USC and Clemson University, Charleston, SC, USA
| | - Martin Morad
- Cardiac Signaling Center of MUSC, USC and Clemson University, Charleston, SC, USA; Department of Regenerative Medicine and Cell Biology, MUSC,Charleston, SC, USA.
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2
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Kharel M, Subedi A, Hossain MF. Hypocalcemic cardiomyopathy with heart failure: A rare Case report. Clin Case Rep 2024; 12:e9463. [PMID: 39314906 PMCID: PMC11417007 DOI: 10.1002/ccr3.9463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Revised: 08/18/2024] [Accepted: 09/07/2024] [Indexed: 09/25/2024] Open
Abstract
Hypocalcemia is one of the rarest causes of reversible cardiomyopathy. Patients with refractory heart failure need to be explored for hypocalcemia and need prompt correction. Abstract Hypocalcemia is a rare cause of reversible dilated cardiomyopathy. Correction of calcium is crucial to recover left ventricular function and structure. We presented the case of a 55-year-old female who was admitted to the hospital with refractory heart failure due to hypocalcemia induced by primary hypoparathyroidism and complicated by vitamin D deficiency. The patient's cardiac symptoms improved dramatically upon correction of hypocalcemia, and vitamin D. Therefore, the key clinical message of this case report is, that hypocalcemia, although rare, should be considered as one of the differential diagnoses when heart failure is refractory and early diagnosis and treatment is necessary as it is the cause of reversible cardiomyopathy and could reduce morbidity and mortality.
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Affiliation(s)
| | | | - Md Fahad Hossain
- Ministry of Health and Family WelfareKuliarcharKishoreganjBangladesh
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3
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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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4
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Le QA, Trinh TN, Luong PK, Anh VTV, Tran HN, Kim JC, Woo SH. The NADPH oxidase inhibitor diphenyleneiodonium suppresses Ca 2+ signaling and contraction in rat cardiac myocytes. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2024; 28:335-344. [PMID: 38926841 PMCID: PMC11211754 DOI: 10.4196/kjpp.2024.28.4.335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 04/14/2024] [Accepted: 04/15/2024] [Indexed: 06/28/2024]
Abstract
Diphenyleneiodonium (DPI) has been widely used as an inhibitor of NADPH oxidase (Nox) to discover its function in cardiac myocytes under various stimuli. However, the effects of DPI itself on Ca2+ signaling and contraction in cardiac myocytes under control conditions have not been understood. We investigated the effects of DPI on contraction and Ca2+ signaling and their underlying mechanisms using video edge detection, confocal imaging, and whole-cell patch clamp technique in isolated rat cardiac myocytes. Application of DPI suppressed cell shortenings in a concentration-dependent manner (IC50 of ≅0.17 µM) with a maximal inhibition of ~70% at ~100 µM. DPI decreased the magnitude of Ca2+ transient and sarcoplasmic reticulum Ca2+ content by 20%-30% at 3 µM that is usually used to remove the Nox activity, with no effect on fractional release. There was no significant change in the half-decay time of Ca2+ transients by DPI. The L-type Ca2+ current (ICa) was decreased concentration-dependently by DPI (IC50 of ≅40.3 µM) with ≅13.1%-inhibition at 3 µM. The frequency of Ca2+ sparks was reduced by 3 µM DPI (by ~25%), which was resistant to a brief removal of external Ca2+ and Na+. Mitochondrial superoxide level was reduced by DPI at 3-100 µM. Our data suggest that DPI may suppress L-type Ca2+ channel and RyR, thereby attenuating Ca2+-induced Ca2+ release and contractility in cardiac myocytes, and that such DPI effects may be related to mitochondrial metabolic suppression.
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Affiliation(s)
- Qui Anh Le
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
| | - Tran Nguyet Trinh
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
| | - Phuong Kim Luong
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
| | - Vu Thi Van Anh
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
| | - Ha Nam Tran
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
| | - Joon-Chul Kim
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
- Nexel Co. Ltd., Seoul 07802, Korea
| | - Sun-Hee Woo
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea
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5
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Liu S, Anderson PJ, Rajagopal S, Lefkowitz RJ, Rockman HA. G Protein-Coupled Receptors: A Century of Research and Discovery. Circ Res 2024; 135:174-197. [PMID: 38900852 PMCID: PMC11192237 DOI: 10.1161/circresaha.124.323067] [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] [Indexed: 06/22/2024]
Abstract
GPCRs (G protein-coupled receptors), also known as 7 transmembrane domain receptors, are the largest receptor family in the human genome, with ≈800 members. GPCRs regulate nearly every aspect of human physiology and disease, thus serving as important drug targets in cardiovascular disease. Sharing a conserved structure comprised of 7 transmembrane α-helices, GPCRs couple to heterotrimeric G-proteins, GPCR kinases, and β-arrestins, promoting downstream signaling through second messengers and other intracellular signaling pathways. GPCR drug development has led to important cardiovascular therapies, such as antagonists of β-adrenergic and angiotensin II receptors for heart failure and hypertension, and agonists of the glucagon-like peptide-1 receptor for reducing adverse cardiovascular events and other emerging indications. There continues to be a major interest in GPCR drug development in cardiovascular and cardiometabolic disease, driven by advances in GPCR mechanistic studies and structure-based drug design. This review recounts the rich history of GPCR research, including the current state of clinically used GPCR drugs, and highlights newly discovered aspects of GPCR biology and promising directions for future investigation. As additional mechanisms for regulating GPCR signaling are uncovered, new strategies for targeting these ubiquitous receptors hold tremendous promise for the field of cardiovascular medicine.
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Affiliation(s)
- Samuel Liu
- Department of Medicine, Duke University Medical
Center
| | - Preston J. Anderson
- Cell and Molecular Biology (CMB), Duke University, Durham,
NC, 27710, USA
- Duke Medical Scientist Training Program, Duke University,
Durham, NC, 27710, USA
| | - Sudarshan Rajagopal
- Department of Medicine, Duke University Medical
Center
- Cell and Molecular Biology (CMB), Duke University, Durham,
NC, 27710, USA
- Deparment of Biochemistry Duke University, Durham, NC,
27710, USA
| | - Robert J. Lefkowitz
- Department of Medicine, Duke University Medical
Center
- Deparment of Biochemistry Duke University, Durham, NC,
27710, USA
- Howard Hughes Medical Institute, Duke University Medical
Center, Durham, North Carolina 27710, USA
| | - Howard A. Rockman
- Department of Medicine, Duke University Medical
Center
- Cell and Molecular Biology (CMB), Duke University, Durham,
NC, 27710, USA
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6
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Rhana P, Matsumoto C, Fong Z, Costa AD, Del Villar SG, Dixon RE, Santana LF. Fueling the heartbeat: Dynamic regulation of intracellular ATP during excitation-contraction coupling in ventricular myocytes. Proc Natl Acad Sci U S A 2024; 121:e2318535121. [PMID: 38865270 PMCID: PMC11194497 DOI: 10.1073/pnas.2318535121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 05/14/2024] [Indexed: 06/14/2024] Open
Abstract
The heart beats approximately 100,000 times per day in humans, imposing substantial energetic demands on cardiac muscle. Adenosine triphosphate (ATP) is an essential energy source for normal function of cardiac muscle during each beat, as it powers ion transport, intracellular Ca2+ handling, and actin-myosin cross-bridge cycling. Despite this, the impact of excitation-contraction coupling on the intracellular ATP concentration ([ATP]i) in myocytes is poorly understood. Here, we conducted real-time measurements of [ATP]i in ventricular myocytes using a genetically encoded ATP fluorescent reporter. Our data reveal rapid beat-to-beat variations in [ATP]i. Notably, diastolic [ATP]i was <1 mM, which is eightfold to 10-fold lower than previously estimated. Accordingly, ATP-sensitive K+ (KATP) channels were active at physiological [ATP]i. Cells exhibited two distinct types of ATP fluctuations during an action potential: net increases (Mode 1) or decreases (Mode 2) in [ATP]i. Mode 1 [ATP]i increases necessitated Ca2+ entry and release from the sarcoplasmic reticulum (SR) and were associated with increases in mitochondrial Ca2+. By contrast, decreases in mitochondrial Ca2+ accompanied Mode 2 [ATP]i decreases. Down-regulation of the protein mitofusin 2 reduced the magnitude of [ATP]i fluctuations, indicating that SR-mitochondrial coupling plays a crucial role in the dynamic control of ATP levels. Activation of β-adrenergic receptors decreased [ATP]i, underscoring the energetic impact of this signaling pathway. Finally, our work suggests that cross-bridge cycling is the largest consumer of ATP in a ventricular myocyte during an action potential. These findings provide insights into the energetic demands of EC coupling and highlight the dynamic nature of ATP concentrations in cardiac muscle.
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Affiliation(s)
- Paula Rhana
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - Collin Matsumoto
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - Zhihui Fong
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - Alexandre D. Costa
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - Silvia G. Del Villar
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - Rose E. Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
| | - L. Fernando Santana
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA95616
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7
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Shi Q, Malik H, Crawford RM, Streeter J, Wang J, Huo R, Shih JC, Chen B, Hall D, Abel ED, Song LS, Anderson EJ. Cardiac monoamine oxidase-A inhibition protects against catecholamine-induced ventricular arrhythmias via enhanced diastolic calcium control. Cardiovasc Res 2024; 120:596-611. [PMID: 38198753 PMCID: PMC11074799 DOI: 10.1093/cvr/cvae012] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 11/01/2023] [Accepted: 11/22/2023] [Indexed: 01/12/2024] Open
Abstract
AIMS A mechanistic link between depression and risk of arrhythmias could be attributed to altered catecholamine metabolism in the heart. Monoamine oxidase-A (MAO-A), a key enzyme involved in catecholamine metabolism and longstanding antidepressant target, is highly expressed in the myocardium. The present study aimed to elucidate the functional significance and underlying mechanisms of cardiac MAO-A in arrhythmogenesis. METHODS AND RESULTS Analysis of the TriNetX database revealed that depressed patients treated with MAO inhibitors had a lower risk of arrhythmias compared with those treated with selective serotonin reuptake inhibitors. This effect was phenocopied in mice with cardiomyocyte-specific MAO-A deficiency (cMAO-Adef), which showed a significant reduction in both incidence and duration of catecholamine stress-induced ventricular tachycardia compared with wild-type mice. Additionally, cMAO-Adef cardiomyocytes exhibited altered Ca2+ handling under catecholamine stimulation, with increased diastolic Ca2+ reuptake, reduced diastolic Ca2+ leak, and diminished systolic Ca2+ release. Mechanistically, cMAO-Adef hearts had reduced catecholamine levels under sympathetic stress, along with reduced levels of reactive oxygen species and protein carbonylation, leading to decreased oxidation of Type II PKA and CaMKII. These changes potentiated phospholamban (PLB) phosphorylation, thereby enhancing diastolic Ca2+ reuptake, while reducing ryanodine receptor 2 (RyR2) phosphorylation to decrease diastolic Ca2+ leak. Consequently, cMAO-Adef hearts exhibited lower diastolic Ca2+ levels and fewer arrhythmogenic Ca2+ waves during sympathetic overstimulation. CONCLUSION Cardiac MAO-A inhibition exerts an anti-arrhythmic effect by enhancing diastolic Ca2+ handling under catecholamine stress.
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MESH Headings
- Animals
- Female
- Humans
- Male
- Mice
- Calcium/metabolism
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism
- Catecholamines/metabolism
- Cells, Cultured
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Diastole/drug effects
- Disease Models, Animal
- Heart Rate/drug effects
- Mice, Inbred C57BL
- Mice, Knockout
- Monoamine Oxidase/metabolism
- Monoamine Oxidase Inhibitors/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phosphorylation
- Reactive Oxygen Species/metabolism
- Ryanodine Receptor Calcium Release Channel/metabolism
- Tachycardia, Ventricular/enzymology
- Tachycardia, Ventricular/physiopathology
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Affiliation(s)
- Qian Shi
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
| | - Hamza Malik
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
| | - Rachel M Crawford
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, 180 S Grand Ave., Iowa City, IA 52242, USA
| | - Jennifer Streeter
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
| | - Jinxi Wang
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
| | - Ran Huo
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, 180 S Grand Ave., Iowa City, IA 52242, USA
| | - Jean C Shih
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089, USA
| | - Biyi Chen
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
| | - Duane Hall
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, CBRB 2267285, Newton Rd, Iowa City, IA 52242, USA
| | - E Dale Abel
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, CBRB 2267285, Newton Rd, Iowa City, IA 52242, USA
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, 169 Newton Rd, Iowa City, IA 52242, USA
| | - Long-Sheng Song
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Rd, Iowa City, IA 52242, USA
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, CBRB 2267285, Newton Rd, Iowa City, IA 52242, USA
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, 169 Newton Rd, Iowa City, IA 52242, USA
| | - Ethan J Anderson
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, 180 S Grand Ave., Iowa City, IA 52242, USA
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, CBRB 2267285, Newton Rd, Iowa City, IA 52242, USA
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, 169 Newton Rd, Iowa City, IA 52242, USA
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8
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Xing Y, Cui T, Sun F. A novel RyR2 mutation associated with co-morbid catecholaminergic polymorphic ventricular tachycardia (CPVT) and benign epilepsy with centrotemporal spikes (BECTS). J Electrocardiol 2024; 84:75-80. [PMID: 38574633 DOI: 10.1016/j.jelectrocard.2024.03.013] [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: 01/23/2024] [Revised: 03/19/2024] [Accepted: 03/19/2024] [Indexed: 04/06/2024]
Abstract
In this case report, we describe a 14-year-old patient with a novel RyR2 gene mutation (c.6577G > T/p.Val2193Leu), identified through a comprehensive review of medical history, examination findings, and follow-up data. The pathogenic potential of this mutation, which results in the loss of some interatomic forces and compromises the closure of the RyR2 protein pore leading to calcium leakage, was analyzed using the I-TASSER Suite to predict the structural changes in the protein. This mutation manifested clinically as co-morbid catecholaminergic polymorphic ventricular tachycardia (CPVT) and benign epilepsy with centrotemporal spikes (BECTS), a combination not previously documented in the same patient. While seizures were successfully managed with levetiracetam, the patient's exercise-induced syncope episodes could not be controlled with metoprolol, highlighting the complexity and challenge in managing CPVT associated with this novel RyR2 variation.
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Affiliation(s)
- Yinxue Xing
- Department of Neurology, Affiliated Xing Tai People Hospital of Hebei Medical University, Xingtai, Hebei, China.
| | - Tao Cui
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; China National Clinical Research Center for Neurological Disease, NCRC-ND, Beijing, China
| | - Fan Sun
- Department of Neurology, Affiliated Hospital of Chengde Medical University, Chengde, Hebei, China
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9
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Haq I, Ngo JC, Roy N, Pan RL, Nawsheen N, Chiu R, Zhang Y, Fujita M, Soni RK, Wu X, Bennett DA, Menon V, Olah M, Sher F. An integrated toolkit for human microglia functional genomics. Stem Cell Res Ther 2024; 15:104. [PMID: 38600587 PMCID: PMC11005142 DOI: 10.1186/s13287-024-03700-9] [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: 09/28/2023] [Accepted: 03/19/2024] [Indexed: 04/12/2024] Open
Abstract
BACKGROUND Microglia, the brain's resident immune cells, play vital roles in brain development, and disorders like Alzheimer's disease (AD). Human iPSC-derived microglia (iMG) provide a promising model to study these processes. However, existing iMG generation protocols face challenges, such as prolonged differentiation time, lack of detailed characterization, and limited gene function investigation via CRISPR-Cas9. METHODS Our integrated toolkit for in-vitro microglia functional genomics optimizes iPSC differentiation into iMG through a streamlined two-step, 20-day process, producing iMG with a normal karyotype. We confirmed the iMG's authenticity and quality through single-cell RNA sequencing, chromatin accessibility profiles (ATAC-Seq), proteomics and functional tests. The toolkit also incorporates a drug-dependent CRISPR-ON/OFF system for temporally controlled gene expression. Further, we facilitate the use of multi-omic data by providing online searchable platform that compares new iMG profiles to human primary microglia: https://sherlab.shinyapps.io/IPSC-derived-Microglia/ . RESULTS Our method generates iMG that closely align with human primary microglia in terms of transcriptomic, proteomic, and chromatin accessibility profiles. Functionally, these iMG exhibit Ca2 + transients, cytokine driven migration, immune responses to inflammatory signals, and active phagocytosis of CNS related substrates including synaptosomes, amyloid beta and myelin. Significantly, the toolkit facilitates repeated iMG harvesting, essential for large-scale experiments like CRISPR-Cas9 screens. The standalone ATAC-Seq profiles of our iMG closely resemble primary microglia, positioning them as ideal tools to study AD-associated single nucleotide variants (SNV) especially in the genome regulatory regions. CONCLUSIONS Our advanced two-step protocol rapidly and efficiently produces authentic iMG. With features like the CRISPR-ON/OFF system and a comprehensive multi-omic data platform, our toolkit equips researchers for robust microglial functional genomic studies. By facilitating detailed SNV investigation and offering a sustainable cell harvest mechanism, the toolkit heralds significant progress in neurodegenerative disease drug research and therapeutic advancement.
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Affiliation(s)
- Imdadul Haq
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Jason C Ngo
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Nainika Roy
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Richard L Pan
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY, USA
| | - Nadiya Nawsheen
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Rebecca Chiu
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
- Neuroimmunology Core, Center for Translational & Computational Neuroimmunology, Division of Neuroimmunology, Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Ya Zhang
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
- Neuroimmunology Core, Center for Translational & Computational Neuroimmunology, Division of Neuroimmunology, Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Masashi Fujita
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Rajesh K Soni
- Proteomics Core, Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Xuebing Wu
- Department of Medicine, Department of Systems Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - David A Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA
| | - Vilas Menon
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Marta Olah
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Falak Sher
- Center for Translational and Computational Neuroimmunology, Columbia University Medical Center, New York, NY, USA.
- Taub Institute for Research on Alzheimer's Disease and Aging Brain, Columbia University Medical Center, New York, NY, USA.
- Department of Neurology, Columbia University Medical Center, New York, NY, USA.
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10
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Asghari P, Scriven DR, Shahrasebi S, Valdivia HH, Alsina KM, Valdivia CR, Navarro-Garcia JA, Wehrens XH, Moore ED. Phosphorylation of RyR2 simultaneously expands the dyad and rearranges the tetramers. J Gen Physiol 2024; 156:e202213108. [PMID: 38385988 PMCID: PMC10883851 DOI: 10.1085/jgp.202213108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 01/23/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
We have previously demonstrated that type II ryanodine receptors (RyR2) tetramers can be rapidly rearranged in response to a phosphorylation cocktail. The cocktail modified downstream targets indiscriminately, making it impossible to determine whether phosphorylation of RyR2 was an essential element of the response. Here, we used the β-agonist isoproterenol and mice homozygous for one of the following clinically relevant mutations: S2030A, S2808A, S2814A, or S2814D. We measured the length of the dyad using transmission electron microscopy (TEM) and directly visualized RyR2 distribution using dual-tilt electron tomography. We found that the S2814D mutation, by itself, significantly expanded the dyad and reorganized the tetramers, suggesting a direct link between the phosphorylation state of the tetramer and its microarchitecture. S2808A and S2814A mutant mice, as well as wild types, had significant expansions of their dyads in response to isoproterenol, while S2030A mutants did not. In agreement with functional data from these mutants, S2030 and S2808 were necessary for a complete β-adrenergic response, unlike S2814 mutants. Additionally, all mutants had unique effects on the organization of their tetramer arrays. Lastly, the correlation of structural with functional changes suggests that tetramer-tetramer contacts play an important functional role. We thus conclude that both the size of the dyad and the arrangement of the tetramers are linked to the state of the channel tetramer and can be dynamically altered by a β-adrenergic receptor agonist.
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Affiliation(s)
- Parisa Asghari
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - David R.L. Scriven
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Saba Shahrasebi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Hector H. Valdivia
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Carmen R. Valdivia
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - J. Alberto Navarro-Garcia
- Department of Integrative Physiology, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander H.T. Wehrens
- Department of Integrative Physiology, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Edwin D.W. Moore
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, Canada
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11
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Crapart CC, Scott ZC, Konno T, Sharma A, Parutto P, Bailey DMD, Westrate LM, Avezov E, Koslover EF. Luminal transport through intact endoplasmic reticulum limits the magnitude of localized Ca 2+ signals. Proc Natl Acad Sci U S A 2024; 121:e2312172121. [PMID: 38502705 PMCID: PMC10990089 DOI: 10.1073/pnas.2312172121] [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: 07/17/2023] [Accepted: 02/09/2024] [Indexed: 03/21/2024] Open
Abstract
The endoplasmic reticulum (ER) forms an interconnected network of tubules stretching throughout the cell. Understanding how ER functionality relies on its structural organization is crucial for elucidating cellular vulnerability to ER perturbations, which have been implicated in several neuronal pathologies. One of the key functions of the ER is enabling Ca[Formula: see text] signaling by storing large quantities of this ion and releasing it into the cytoplasm in a spatiotemporally controlled manner. Through a combination of physical modeling and live-cell imaging, we demonstrate that alterations in ER shape significantly impact its ability to support efficient local Ca[Formula: see text] releases, due to hindered transport of luminal content within the ER. Our model reveals that rapid Ca[Formula: see text] release necessitates mobile luminal buffer proteins with moderate binding strength, moving through a well-connected network of ER tubules. These findings provide insight into the functional advantages of normal ER architecture, emphasizing its importance as a kinetically efficient intracellular Ca[Formula: see text] delivery system.
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Affiliation(s)
- Cécile C. Crapart
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | | | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Aman Sharma
- Department of Physics, University of California, San Diego, La Jolla, CA92130
| | - Pierre Parutto
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - David M. D. Bailey
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Laura M. Westrate
- Department of Chemistry and Biochemistry, Calvin University, Grand Rapids, MI49546
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge, CambridgeCB2 0AH, United Kingdom
- Department of Clinical Neurosciences, School of Clinical Medicine, The University of Cambridge, CambridgeCB2 0AH, United Kingdom
| | - Elena F. Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA92130
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12
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Xu J, Liao C, Yin CC, Li G, Zhu Y, Sun F. In situ structural insights into the excitation-contraction coupling mechanism of skeletal muscle. SCIENCE ADVANCES 2024; 10:eadl1126. [PMID: 38507485 PMCID: PMC10954225 DOI: 10.1126/sciadv.adl1126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 02/12/2024] [Indexed: 03/22/2024]
Abstract
Excitation-contraction coupling (ECC) is a fundamental mechanism in control of skeletal muscle contraction and occurs at triad junctions, where dihydropyridine receptors (DHPRs) on transverse tubules sense excitation signals and then cause calcium release from the sarcoplasmic reticulum via coupling to type 1 ryanodine receptors (RyR1s), inducing the subsequent contraction of muscle filaments. However, the molecular mechanism remains unclear due to the lack of structural details. Here, we explored the architecture of triad junction by cryo-electron tomography, solved the in situ structure of RyR1 in complex with FKBP12 and calmodulin with the resolution of 16.7 Angstrom, and found the intact RyR1-DHPR supercomplex. RyR1s arrange into two rows on the terminal cisternae membrane by forming right-hand corner-to-corner contacts, and tetrads of DHPRs bind to RyR1s in an alternating manner, forming another two rows on the transverse tubule membrane. This unique arrangement is important for synergistic calcium release and provides direct evidence of physical coupling in ECC.
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Affiliation(s)
- Jiashu Xu
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chenyi Liao
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Chang-Cheng Yin
- Department of Biophysics, The Health Science Center, Peking University, Beijing 100191, China
- Electron Microscopy Analysis Laboratory, The Health Science Center, Peking University, Beijing 100191, China
- Center for Protein Science, Peking University, Beijing 100871, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yun Zhu
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Fei Sun
- Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, Guangdong, 510005, China
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13
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Johnson SC, Annamdevula NS, Leavesley SJ, Francis CM, Rich TC. Hyperspectral imaging and dynamic region of interest tracking approaches to quantify localized cAMP signals. Biochem Soc Trans 2024; 52:191-203. [PMID: 38334148 PMCID: PMC11115359 DOI: 10.1042/bst20230352] [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: 11/15/2023] [Revised: 01/10/2024] [Accepted: 01/15/2024] [Indexed: 02/10/2024]
Abstract
Cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger known to orchestrate a myriad of cellular functions over a wide range of timescales. In the last 20 years, a variety of single-cell sensors have been developed to measure second messenger signals including cAMP, Ca2+, and the balance of kinase and phosphatase activities. These sensors utilize changes in fluorescence emission of an individual fluorophore or Förster resonance energy transfer (FRET) to detect changes in second messenger concentration. cAMP and kinase activity reporter probes have provided powerful tools for the study of localized signals. Studies relying on these and related probes have the potential to further revolutionize our understanding of G protein-coupled receptor signaling systems. Unfortunately, investigators have not been able to take full advantage of the potential of these probes due to the limited signal-to-noise ratio of the probes and the limited ability of standard epifluorescence and confocal microscope systems to simultaneously measure the distributions of multiple signals (e.g. cAMP, Ca2+, and changes in kinase activities) in real time. In this review, we focus on recently implemented strategies to overcome these limitations: hyperspectral imaging and adaptive thresholding approaches to track dynamic regions of interest (ROI). This combination of approaches increases signal-to-noise ratio and contrast, and allows identification of localized signals throughout cells. These in turn lead to the identification and quantification of intracellular signals with higher effective resolution. Hyperspectral imaging and dynamic ROI tracking approaches offer investigators additional tools with which to visualize and quantify multiplexed intracellular signaling systems.
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Affiliation(s)
- Santina C Johnson
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Naga S Annamdevula
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Department of Physiology and Cell Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Silas J Leavesley
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Chemical and Biomolecular Engineering, University of South Alabama, Mobile, AL, U.S.A
| | - C Michael Francis
- Department of Physiology and Cell Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
| | - Thomas C Rich
- Department of Pharmacology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
- Center for Lung Biology, Frederick P. Whiddon College of Medicine, University of South Alabama, Mobile, AL, U.S.A
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14
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Scheibner C, Ori H, Cohen AE, Vitelli V. Spiking at the edge: Excitability at interfaces in reaction-diffusion systems. Proc Natl Acad Sci U S A 2024; 121:e2307996120. [PMID: 38215183 PMCID: PMC10801884 DOI: 10.1073/pnas.2307996120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 10/25/2023] [Indexed: 01/14/2024] Open
Abstract
Excitable media, ranging from bioelectric tissues and chemical oscillators to forest fires and competing populations, are nonlinear, spatially extended systems capable of spiking. Most investigations of excitable media consider situations where the amplifying and suppressing forces necessary for spiking coexist at every point in space. In this case, spikes arise due to local bistabilities, which require a fine-tuned ratio between local amplification and suppression strengths. But, in nature and engineered systems, these forces can be segregated in space, forming structures like interfaces and boundaries. Here, we show how boundaries can generate and protect spiking when the reacting components can spread out: Even arbitrarily weak diffusion can cause spiking at the edge between two non-excitable media. This edge spiking arises due to a global bistability, which can occur even if amplification and suppression strengths do not allow spiking when mixed. We analytically derive a spiking phase diagram that depends on two parameters: i) the ratio between the system size and the characteristic diffusive length-scale and ii) the ratio between the amplification and suppression strengths. Our analysis explains recent experimental observations of action potentials at the interface between two non-excitable bioelectric tissues. Beyond electrophysiology, we highlight how edge spiking emerges in predator-prey dynamics and in oscillating chemical reactions. Our findings provide a theoretical blueprint for a class of interfacial excitations in reaction-diffusion systems, with potential implications for spatially controlled chemical reactions, nonlinear waveguides and neuromorphic computation, as well as spiking instabilities, such as cardiac arrhythmias, that naturally occur in heterogeneous biological media.
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Affiliation(s)
- Colin Scheibner
- Department of Physics and The James Franck Institute, The University of Chicago, Chicago, IL60637
- Kadanoff Center for Theoretical Physics, The University of Chicago, Chicago, IL60637
| | - Hillel Ori
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA02138
| | - Adam E. Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA02138
- Department of Physics, Harvard University, Cambridge, MA02138
| | - Vincenzo Vitelli
- Department of Physics and The James Franck Institute, The University of Chicago, Chicago, IL60637
- Kadanoff Center for Theoretical Physics, The University of Chicago, Chicago, IL60637
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL60637
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15
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Mensah IK, Emerson ML, Tan HJ, Gowher H. Cardiomyocyte Differentiation from Mouse Embryonic Stem Cells by WNT Switch Method. Cells 2024; 13:132. [PMID: 38247824 PMCID: PMC10814988 DOI: 10.3390/cells13020132] [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: 12/13/2023] [Revised: 01/02/2024] [Accepted: 01/09/2024] [Indexed: 01/23/2024] Open
Abstract
The differentiation of ESCs into cardiomyocytes in vitro is an excellent and reliable model system for studying normal cardiomyocyte development in mammals, modeling cardiac diseases, and for use in drug screening. Mouse ESC differentiation still provides relevant biological information about cardiac development. However, the current methods for efficiently differentiating ESCs into cardiomyocytes are limiting. Here, we describe the "WNT Switch" method to efficiently commit mouse ESCs into cardiomyocytes using the small molecule WNT signaling modulators CHIR99021 and XAV939 in vitro. This method significantly improves the yield of beating cardiomyocytes, reduces number of treatments, and is less laborious.
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Affiliation(s)
| | | | | | - Humaira Gowher
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; (I.K.M.); (H.J.T.)
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16
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Aboonabi A, McCauley MD. Myofilament dysfunction in diastolic heart failure. Heart Fail Rev 2024; 29:79-93. [PMID: 37837495 PMCID: PMC10904515 DOI: 10.1007/s10741-023-10352-z] [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] [Accepted: 09/18/2023] [Indexed: 10/16/2023]
Abstract
Diastolic heart failure (DHF), in which impaired ventricular filling leads to typical heart failure symptoms, represents over 50% of all heart failure cases and is linked with risk factors, including metabolic syndrome, hypertension, diabetes, and aging. A substantial proportion of patients with this disorder maintain normal left ventricular systolic function, as assessed by ejection fraction. Despite the high prevalence of DHF, no effective therapeutic agents are available to treat this condition, partially because the molecular mechanisms of diastolic dysfunction remain poorly understood. As such, by focusing on the underlying molecular and cellular processes contributing to DHF can yield new insights that can represent an exciting new avenue and propose a novel therapeutic approach for DHF treatment. This review discusses new developments from basic and clinical/translational research to highlight current knowledge gaps, help define molecular determinants of diastolic dysfunction, and clarify new targets for treatment.
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Affiliation(s)
- Anahita Aboonabi
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago, 840 S. Wood St., 920S (MC 715), Chicago, IL, 60612, USA.
- Jesse Brown VA Medical Center, Chicago, IL, USA.
| | - Mark D McCauley
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago, 840 S. Wood St., 920S (MC 715), Chicago, IL, 60612, USA.
- Jesse Brown VA Medical Center, Chicago, IL, USA.
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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17
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Ananthamohan K, Stelzer JE, Sadayappan S. Hypertrophic cardiomyopathy in MYBPC3 carriers in aging. THE JOURNAL OF CARDIOVASCULAR AGING 2024; 4:9. [PMID: 38406555 PMCID: PMC10883298 DOI: 10.20517/jca.2023.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.
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Affiliation(s)
- Kalyani Ananthamohan
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Julian E. Stelzer
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 45267, USA
| | - Sakthivel Sadayappan
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, OH 45267, USA
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18
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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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19
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Hurley ME, Shah SS, Sheard TMD, Kirton HM, Steele DS, Gamper N, Jayasinghe I. Super-Resolution Analysis of the Origins of the Elementary Events of ER Calcium Release in Dorsal Root Ganglion Neurons. Cells 2023; 13:38. [PMID: 38201242 PMCID: PMC10778190 DOI: 10.3390/cells13010038] [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: 11/20/2023] [Revised: 12/18/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Coordinated events of calcium (Ca2+) released from the endoplasmic reticulum (ER) are key second messengers in excitable cells. In pain-sensing dorsal root ganglion (DRG) neurons, these events can be observed as Ca2+ sparks, produced by a combination of ryanodine receptors (RyR) and inositol 1,4,5-triphosphate receptors (IP3R1). These microscopic signals offer the neuronal cells with a possible means of modulating the subplasmalemmal Ca2+ handling, initiating vesicular exocytosis. With super-resolution dSTORM and expansion microscopies, we visualised the nanoscale distributions of both RyR and IP3R1 that featured loosely organised clusters in the subplasmalemmal regions of cultured rat DRG somata. We adapted a novel correlative microscopy protocol to examine the nanoscale patterns of RyR and IP3R1 in the locality of each Ca2+ spark. We found that most subplasmalemmal sparks correlated with relatively small groups of RyR whilst larger sparks were often associated with larger groups of IP3R1. These data also showed spontaneous Ca2+ sparks in <30% of the subplasmalemmal cell area but consisted of both these channel species at a 3.8-5 times higher density than in nonactive regions of the cell. Taken together, these observations reveal distinct patterns and length scales of RyR and IP3R1 co-clustering at contact sites between the ER and the surface plasmalemma that encode the positions and the quantity of Ca2+ released at each Ca2+ spark.
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Affiliation(s)
- Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Shihab S. Shah
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas M. D. Sheard
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Hannah M. Kirton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Derek S. Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
- EMBL Australia Node in Single Molecule Science, School of Biomedical Science, University of New South Wales, Kensington, Sydney 2052, Australia
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20
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Fear VS, Forbes CA, Shaw NC, Farley KO, Mantegna JL, Htun JP, Syn G, Viola H, Cserne Szappanos H, Hool L, Ward M, Baynam G, Lassmann T. Gene editing and cardiac disease modelling for the interpretation of genetic variants of uncertain significance in congenital heart disease. Stem Cell Res Ther 2023; 14:345. [PMID: 38049901 PMCID: PMC10696868 DOI: 10.1186/s13287-023-03592-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 11/29/2023] [Indexed: 12/06/2023] Open
Abstract
BACKGROUND Genomic sequencing in congenital heart disease (CHD) patients often discovers novel genetic variants, which are classified as variants of uncertain significance (VUS). Functional analysis of each VUS is required in specialised laboratories, to determine whether the VUS is disease causative or not, leading to lengthy diagnostic delays. We investigated stem cell cardiac disease modelling and transcriptomics for the purpose of genetic variant classification using a GATA4 (p.Arg283Cys) VUS in a patient with CHD. METHODS We performed high efficiency CRISPR gene editing with homology directed repair in induced pluripotent stem cells (iPSCs), followed by rapid clonal selection with amplicon sequencing. Genetic variant and healthy matched control cells were compared using cardiomyocyte disease modelling and transcriptomics. RESULTS Genetic variant and healthy cardiomyocytes similarly expressed Troponin T (cTNNT), and GATA4. Transcriptomics analysis of cardiomyocyte differentiation identified changes consistent with the patient's clinical human phenotype ontology terms. Further, transcriptomics revealed changes in calcium signalling, and cardiomyocyte adrenergic signalling in the variant cells. Functional testing demonstrated, altered action potentials in GATA4 genetic variant cardiomyocytes were consistent with patient cardiac abnormalities. CONCLUSIONS This work provides in vivo functional studies supportive of a damaging effect on the gene or gene product. Furthermore, we demonstrate the utility of iPSCs, CRISPR gene editing and cardiac disease modelling for genetic variant interpretation. The method can readily be applied to other genetic variants in GATA4 or other genes in cardiac disease, providing a centralised assessment pathway for patient genetic variant interpretation.
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Affiliation(s)
- Vanessa S Fear
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia.
- Centre for Child Health Research, University of Western Australia, Crawley, Australia.
- Telethon Kids Institute, Northern Entrance, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, WA, 6009, Australia.
| | - Catherine A Forbes
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Nicole C Shaw
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Kathryn O Farley
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
- Computational Biology, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Jessica L Mantegna
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Jasmin P Htun
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Genevieve Syn
- Computational Biology, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
| | - Helena Viola
- University of Western Australia, Crawley, Australia
| | | | - Livia Hool
- University of Western Australia, Crawley, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Michelle Ward
- Undiagnosed Diseases Program, Genetic Services of WA, Subiaco, Australia
| | - Gareth Baynam
- Western Australian Register of Developmental Anomalies, King Edward Memorial Hospital, Subiaco, WA, 6008, Australia
- Undiagnosed Diseases Program, Genetic Services of WA, Subiaco, Australia
| | - Timo Lassmann
- Translational Genetics, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
- Computational Biology, Precision Health, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, 6009, Australia
- Centre for Child Health Research, University of Western Australia, Crawley, Australia
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21
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Waddell HMM, Mereacre V, Alvarado FJ, Munro ML. Clustering properties of the cardiac ryanodine receptor in health and heart failure. J Mol Cell Cardiol 2023; 185:38-49. [PMID: 37890552 PMCID: PMC10717225 DOI: 10.1016/j.yjmcc.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/09/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
The cardiac ryanodine receptor (RyR2) is an intracellular Ca2+ release channel vital for the function of the heart. Physiologically, RyR2 is triggered to release Ca2+ from the sarcoplasmic reticulum (SR) which enables cardiac contraction; however, spontaneous Ca2+ leak from RyR2 has been implicated in the pathophysiology of heart failure (HF). RyR2 channels have been well documented to assemble into clusters within the SR membrane, with the organisation of RyR2 clusters recently gaining interest as a mechanism by which the occurrence of pathological Ca2+ leak is regulated, including in HF. In this review, we explain the terminology relating to key nanoscale RyR2 clustering properties as both single clusters and functionally grouped Ca2+ release units, with a focus on the advancements in super-resolution imaging approaches which have enabled the detailed study of cluster organisation. Further, we discuss proposed mechanisms for modulating RyR2 channel organisation and the debate regarding the potential impact of cluster organisation on Ca2+ leak activity. Finally, recent experimental evidence investigating the nanoscale remodelling and functional alterations of RyR2 clusters in HF is discussed with consideration of the clinical implications.
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Affiliation(s)
- Helen M M Waddell
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Valeria Mereacre
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Francisco J Alvarado
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
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22
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Toth N, Zhang XH, Zamaro A, Morad M. Calcium Signaling Consequences of RyR2-S4938F Mutation Expressed in Human iPSC-Derived Cardiomyocytes. Int J Mol Sci 2023; 24:15307. [PMID: 37894987 PMCID: PMC10607246 DOI: 10.3390/ijms242015307] [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: 09/14/2023] [Revised: 10/02/2023] [Accepted: 10/14/2023] [Indexed: 10/29/2023] Open
Abstract
Type-2 ryanodine receptor (RyR2) is the major Ca2+ release channel of the cardiac sarcoplasmic reticulum (SR) that controls the rhythm and strength of the heartbeat, but its malfunction may generate severe arrhythmia leading to sudden cardiac death or heart failure. S4938F-RyR2 mutation in the carboxyl-terminal was expressed in human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) using CRISPR/Cas9 gene-editing technique. Ca2+ signaling and electrophysiological properties of beating cardiomyocytes carrying the mutation were studied using total internal reflection fluorescence microscopy (TIRF) and patch clamp technique. In mutant cells, L-type Ca2+ currents (ICa), measured either by depolarizations to zero mV or repolarizations from +100 mV to -50 mV, and their activated Ca2+ transients were significantly smaller, despite their larger caffeine-triggered Ca2+ release signals compared to wild type (WT) cells, suggesting ICa-induced Ca2+ release (CICR) was compromised. The larger SR Ca2+ content of S4938F-RyR2 cells may underlie the higher frequency of spontaneously occurring Ca2+ sparks and Ca2+ transients and their arrhythmogenic phenotype.
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Affiliation(s)
- Noemi Toth
- Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, USA; (N.T.); (X.-H.Z.)
| | - Xiao-Hua Zhang
- Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, USA; (N.T.); (X.-H.Z.)
| | - Alexandra Zamaro
- Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, USA; (N.T.); (X.-H.Z.)
| | - Martin Morad
- Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, USA; (N.T.); (X.-H.Z.)
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA
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23
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Gil Montoya DC, Ornelas-Guevara R, Diercks BP, Guse AH, Dupont G. T cell Ca 2+ microdomains through the lens of computational modeling. Front Immunol 2023; 14:1235737. [PMID: 37860008 PMCID: PMC10582754 DOI: 10.3389/fimmu.2023.1235737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/18/2023] [Indexed: 10/21/2023] Open
Abstract
Cellular Ca2+ signaling is highly organized in time and space. Locally restricted and short-lived regions of Ca2+ increase, called Ca2+ microdomains, constitute building blocks that are differentially arranged to create cellular Ca2+ signatures controlling physiological responses. Here, we focus on Ca2+ microdomains occurring in restricted cytosolic spaces between the plasma membrane and the endoplasmic reticulum, called endoplasmic reticulum-plasma membrane junctions. In T cells, these microdomains have been finely characterized. Enough quantitative data are thus available to develop detailed computational models of junctional Ca2+ dynamics. Simulations are able to predict the characteristics of Ca2+ increases at the level of single channels and in junctions of different spatial configurations, in response to various signaling molecules. Thanks to the synergy between experimental observations and computational modeling, a unified description of the molecular mechanisms that create Ca2+ microdomains in the first seconds of T cell stimulation is emerging.
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Affiliation(s)
- Diana C. Gil Montoya
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roberto Ornelas-Guevara
- Unit of Theoretical Chronobiology, Faculté des Sciences CP231, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Björn-Philipp Diercks
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas H. Guse
- The Calcium Signalling Group, Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Geneviève Dupont
- Unit of Theoretical Chronobiology, Faculté des Sciences CP231, Université Libre de Bruxelles (ULB), Brussels, Belgium
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24
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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: 18] [Impact Index Per Article: 18.0] [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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25
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Karbowski M, Boyman L, Garber L, Joca HC, Verhoeven N, Coleman AK, Ward CW, Lederer WJ, Greiser M. Na + /K + ATPase-Ca v 1.2 nanodomain differentially regulates intracellular [Na + ], [Ca 2+ ] and local adrenergic signaling in cardiac myocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.553598. [PMID: 37693446 PMCID: PMC10491240 DOI: 10.1101/2023.08.31.553598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Background The intracellular Na + concentration ([Na + ] i ) is a crucial but understudied regulator of cardiac myocyte function. The Na + /K + ATPase (NKA) controls the steady-state [Na + ] i and thereby determines the set-point for intracellular Ca 2+ . Here, we investigate the nanoscopic organization and local adrenergic regulation of the NKA macromolecular complex and how it differentially regulates the intracellular Na + and Ca 2+ homeostases in atrial and ventricular myocytes. Methods Multicolor STORM super-resolution microscopy, Western Blot analyses, and in vivo examination of adrenergic regulation are employed to examine the organization and function of Na + nanodomains in cardiac myocytes. Quantitative fluorescence microscopy at high spatiotemporal resolution is used in conjunction with cellular electrophysiology to investigate intracellular Na + homeostasis in atrial and ventricular myocytes. Results The NKAα1 (NKAα1) and the L-type Ca 2+ -channel (Ca v 1.2) form a nanodomain with a center-to center distance of ∼65 nm in both ventricular and atrial myocytes. NKAα1 protein expression levels are ∼3 fold higher in atria compared to ventricle. 100% higher atrial I NKA , produced by large NKA "superclusters", underlies the substantially lower Na + concentration in atrial myocytes compared to the benchmark values set in ventricular myocytes. The NKA's regulatory protein phospholemman (PLM) has similar expression levels across atria and ventricle resulting in a much lower PLM/NKAα1 ratio for atrial compared to ventricular tissue. In addition, a huge PLM phosphorylation reserve in atrial tissue produces a high ß-adrenergic sensitivity of I NKA in atrial myocytes. ß-adrenergic regulation of I NKA is locally mediated in the NKAα1-Ca v 1.2 nanodomain via A-kinase anchoring proteins. Conclusions NKAα1, Ca v 1.2 and their accessory proteins form a structural and regulatory nanodomain at the cardiac dyad. The tissue-specific composition and local adrenergic regulation of this "signaling cloud" is a main regulator of the distinct global intracellular Na + and Ca 2+ concentrations in atrial and ventricular myocytes.
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26
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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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27
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Zhang X, Aggarwal P, Broeckel U, Abassi YA. Enhancing the functional maturity of hiPSC-derived cardiomyocytes to assess inotropic compounds. J Pharmacol Toxicol Methods 2023; 123:107282. [PMID: 37419294 DOI: 10.1016/j.vascn.2023.107282] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/19/2023] [Accepted: 07/04/2023] [Indexed: 07/09/2023]
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) present an attractive in vitro platform to model safety and toxicity assessments-notably screening pro-arrhythmic compounds. The utility of the platform is stymied by a hiPSC-CM contractile apparatus and calcium handling mechanism akin to fetal phenotypes, evidenced by a negative force-frequency relationship. As such, hiPSC-CMs are limited in their ability to assess compounds that modulate contraction mediated by ionotropic compounds (Robertson, Tran, & George, 2013). To address this limitation, we utilize Agilent's xCELLigence Real-Time Cell Analyzer ePacer (RTCA ePacer) to enhance hiPSC-CM functional maturity. A continuous, progressive increase of electrical pacing is applied to hiPSC-CMs for up to 15 days. Contraction and viability are recorded by measurement of impedance using the RTCA ePacer. Our data confirms hiPSC-CMs inherently demonstrate a negative impedance amplitude frequency that is reversed after long-term electrical pacing. The data also indicate positive inotropic compounds increase the contractility of paced cardiomyocytes and calcium handling machinery is improved. Increased expression of genes critical to cardiomyocyte maturation further underscores the maturity of paced cells. In summary, our data suggest the application of continuous electrical pacing can functionally mature hiPSC-CMs, enhancing cellular response to positive inotropic compounds and improving calcium handling. SUMMARY: Long-term electrical stimulation of hiPSC-CM leads to functional maturation enabling predictive assessment of inotropic compounds.
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28
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Kong CHT, Cannell MB. Ca 2+ spark latency and control of intrinsic Ca 2+ release dyssynchrony in rat cardiac ventricular muscle cells. J Mol Cell Cardiol 2023; 182:44-53. [PMID: 37433391 DOI: 10.1016/j.yjmcc.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/12/2023] [Accepted: 07/06/2023] [Indexed: 07/13/2023]
Abstract
Cardiac excitation-contraction coupling (ECC) depends on Ca2+ release from intracellular stores via ryanodine receptors (RyRs) triggered by L-type Ca2+ channels (LCCs). Uncertain numbers of RyRs and LCCs form 'couplons' whose activation produces Ca2+ sparks, which summate to form a cell-wide Ca2+ transient that switches on contraction. Voltage (Vm) changes during the action potential (AP) and stochasticity in channel gating should create variability in Ca2+ spark timing, but Ca2+ transient wavefronts have remarkable uniformity. To examine how this is achieved, we measured the Vm-dependence of evoked Ca2+ spark probability (Pspark) and latency over a wide voltage range in rat ventricular cells. With depolarising steps, Ca2+ spark latency showed a U-shaped Vm-dependence, while repolarising steps from 50 mV produced Ca2+ spark latencies that increased monotonically with Vm. A computer model based on reported channel gating and geometry reproduced our experimental data and revealed a likely RyR:LCC stoichiometry of ∼ 5:1 for the Ca2+ spark initiating complex (IC). Using the experimental AP waveform, the model revealed a high coupling fidelity (Pcpl ∼ 0.5) between each LCC opening and IC activation. The presence of ∼ 4 ICs per couplon reduced Ca2+ spark latency and increased Pspark to match experimental data. Variability in AP release timing is less than that seen with voltage steps because the AP overshoot and later repolarization decrease Pspark due to effects on LCC flux and LCC deactivation respectively. This work provides a framework for explaining the Vm- and time-dependence of Pspark, and indicates how ion channel dispersion in disease can contribute to dyssynchrony in Ca2+ release.
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Affiliation(s)
- Cherrie H T Kong
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
| | - Mark B Cannell
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
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29
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Dries E, Gilbert G, Roderick HL, Sipido KR. The ryanodine receptor microdomain in cardiomyocytes. Cell Calcium 2023; 114:102769. [PMID: 37390591 DOI: 10.1016/j.ceca.2023.102769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/11/2023] [Accepted: 06/12/2023] [Indexed: 07/02/2023]
Abstract
The ryanodine receptor type 2 (RyR) is a key player in Ca2+ handling during excitation-contraction coupling. During each heartbeat, RyR channels are responsible for linking the action potential with the contractile machinery of the cardiomyocyte by releasing Ca2+ from the sarcoplasmic reticulum. RyR function is fine-tuned by associated signalling molecules, arrangement in clusters and subcellular localization. These parameters together define RyR function within microdomains and are subject to disease remodelling. This review describes the latest findings on RyR microdomain organization, the alterations with disease which result in increased subcellular heterogeneity and emergence of microdomains with enhanced arrhythmogenic potential, and presents novel technologies that guide future research to study and target RyR channels within specific microdomains.
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Affiliation(s)
- Eef Dries
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
| | - Guillaume Gilbert
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Laboratoire ORPHY EA 4324, Université de Brest, Brest, France
| | - H Llewelyn Roderick
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Karin R Sipido
- Lab of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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30
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Alvarez JAE, Jafri MS, Ullah A. Local Control Model of a Human Ventricular Myocyte: An Exploration of Frequency-Dependent Changes and Calcium Sparks. Biomolecules 2023; 13:1259. [PMID: 37627324 PMCID: PMC10452762 DOI: 10.3390/biom13081259] [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: 07/03/2023] [Revised: 08/07/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Calcium (Ca2+) sparks are the elementary events of excitation-contraction coupling, yet they are not explicitly represented in human ventricular myocyte models. A stochastic ventricular cardiomyocyte human model that adapts to intracellular Ca2+ ([Ca2+]i) dynamics, spark regulation, and frequency-dependent changes in the form of locally controlled Ca2+ release was developed. The 20,000 CRUs in this model are composed of 9 individual LCCs and 49 RyRs that function as couplons. The simulated action potential duration at 1 Hz steady-state pacing is ~0.280 s similar to human ventricular cell recordings. Rate-dependence experiments reveal that APD shortening mechanisms are largely contributed by the L-type calcium channel inactivation, RyR open fraction, and [Ca2+]myo concentrations. The dynamic slow-rapid-slow pacing protocol shows that RyR open probability during high pacing frequency (2.5 Hz) switches to an adapted "nonconducting" form of Ca2+-dependent transition state. The predicted force was also observed to be increased in high pacing, but the SR Ca2+ fractional release was lower due to the smaller difference between diastolic and systolic [Ca2+]SR. Restitution analysis through the S1S2 protocol and increased LCC Ca2+-dependent activation rate show that the duration of LCC opening helps modulate its effects on the APD restitution at different diastolic intervals. Ultimately, a longer duration of calcium sparks was observed in relation to the SR Ca2+ loading at high pacing rates. Overall, this study demonstrates the spontaneous Ca2+ release events and ion channel responses throughout various stimuli.
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Affiliation(s)
| | - 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
| | - Aman Ullah
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
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31
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Zhang X, Ni H, Morotti S, Smith C, Sato D, Louch W, Edwards A, Grandi E. Mechanisms of spontaneous Ca 2+ release-mediated arrhythmia in a novel 3D human atrial myocyte model: I. Transverse-axial tubule variation. J Physiol 2023; 601:2655-2683. [PMID: 36094888 PMCID: PMC10008525 DOI: 10.1113/jp283363] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/02/2022] [Indexed: 11/08/2022] Open
Abstract
Intracellular calcium (Ca2+ ) cycling is tightly regulated in the healthy heart ensuring effective contraction. This is achieved by transverse (t)-tubule membrane invaginations that facilitate close coupling of key Ca2+ -handling proteins such as the L-type Ca2+ channel and Na+ -Ca2+ exchanger (NCX) on the cell surface with ryanodine receptors (RyRs) on the intracellular Ca2+ store. Although less abundant and regular than in the ventricle, t-tubules also exist in atrial myocytes as a network of transverse invaginations with axial extensions known as the transverse-axial tubule system (TATS). In heart failure and atrial fibrillation, there is TATS remodelling that is associated with aberrant Ca2+ -handling and Ca2+ -induced arrhythmic activity; however, the mechanism underlying this is not fully understood. To address this, we developed a novel 3D human atrial myocyte model that couples electrophysiology and Ca2+ -handling with variable TATS organization and density. We extensively parameterized and validated our model against experimental data to build a robust tool examining TATS regulation of subcellular Ca2+ release. We found that varying TATS density and thus the localization of key Ca2+ -handling proteins has profound effects on Ca2+ handling. Following TATS loss, there is reduced NCX that results in increased cleft Ca2+ concentration through decreased Ca2+ extrusion. This elevated Ca2+ increases RyR open probability causing spontaneous Ca2+ releases and the promotion of arrhythmogenic waves (especially in the cell interior) leading to voltage instabilities through delayed afterdepolarizations. In summary, the present study demonstrates a mechanistic link between TATS remodelling and Ca2+ -driven proarrhythmic behaviour that probably reflects the arrhythmogenic state observed in disease. KEY POINTS: Transverse-axial tubule systems (TATS) modulate Ca2+ handling and excitation-contraction coupling in atrial myocytes, with TATS remodelling in heart failure and atrial fibrillation being associated with altered Ca2+ cycling and subsequent arrhythmogenesis. To investigate the poorly understood mechanisms linking TATS variation and spontaneous Ca2+ release, we built, parameterized and validated a 3D human atrial myocyte model coupling electrophysiology and spatially-detailed subcellular Ca2+ handling governed by the TATS. Simulated TATS loss causes diastolic Ca2+ and voltage instabilities through reduced Na+ -Ca2+ exchanger-mediated Ca2+ removal, cleft Ca2+ accumulation and increased ryanodine receptor open probability, resulting in spontaneous Ca2+ release and promotion of arrhythmogenic waves and delayed afterdepolarizations. At fast electrical rates typical of atrial tachycardia/fibrillation, spontaneous Ca2+ releases are larger and more frequent in the cell interior than at the periphery. Our work provides mechanistic insight into how atrial TATS remodelling can lead to Ca2+ -driven instabilities that may ultimately contribute to the arrhythmogenic state in disease.
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Affiliation(s)
- X. Zhang
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - H. Ni
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - S. Morotti
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - C.E.R. Smith
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - D. Sato
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - W.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
| | - A.G. Edwards
- Department of Pharmacology, University of California Davis, Davis, CA, USA
- Simula Research Laboratory, Lysaker, Norway
| | - E. Grandi
- Department of Pharmacology, University of California Davis, Davis, CA, USA
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Asghari P, Scriven DRL, Shahrasebi S, Valdivia HH, Wehrens XHT, Moore EDW. PHOSPHORYLATION OF RyR2 SIMULTANEOUSLY EXPANDS THE DYAD AND REARRANGES THE TETRAMERS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.23.541024. [PMID: 37292875 PMCID: PMC10245935 DOI: 10.1101/2023.05.23.541024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have previously demonstrated that type II ryanodine receptors (RyR2) tetramers can be rapidly rearranged in response to a phosphorylation cocktail. The cocktail modified downstream targets indiscriminately making it impossible to determine whether phosphorylation of RyR2 was an essential element of the response. We therefore used the β-agonist isoproterenol and mice with one of the homozygous mutations, S2030A +/+ , S2808A +/+ , S2814A +/+ , or S2814D +/+ , to address this question and to elucidate the role of these clinically relevant mutations. We measured the length of the dyad using transmission electron microscopy (TEM) and directly visualized RyR2 distribution using dual-tilt electron tomography. We found that: 1) The S2814D mutation, by itself, significantly expanded the dyad and reorganized the tetramers suggesting a direct link between the phosphorylation state of the tetramer and the microarchitecture. 2) All of the wild-type, as well as the S2808A and S2814A mice, had significant expansions of their dyads in response to ISO, while S2030A did not. 3) In agreement with functional data from the same mutants, S2030 and S2808 were necessary for a complete β-adrenergic response, whereas S2814 was not. 4) All the mutated residues had unique effects on the organization of their tetramer arrays. 5) The correlation of structure with function suggests that tetramer-tetramer contacts play an important functional role. We conclude that both the size of the dyad and the arrangement of the tetramers are linked to the state of the channel tetramer and can be dynamically altered by a β-adrenergic receptor agonist. Summary Analysis of RyR2 mutants suggests a direct link between the phosphorylation state of the channel tetramer and the microarchitecture of the dyad. All phosphorylation site mutations produced significant and unique effects on the structure of the dyad and its response to isoproterenol.
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Hurley ME, White E, Sheard TMD, Steele D, Jayasinghe I. Correlative super-resolution analysis of cardiac calcium sparks and their molecular origins in health and disease. Open Biol 2023; 13:230045. [PMID: 37220792 PMCID: PMC10205181 DOI: 10.1098/rsob.230045] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 04/28/2023] [Indexed: 05/25/2023] Open
Abstract
Rapid release of calcium from internal stores via ryanodine receptors (RyRs) is one of the fastest types of cytoplasmic second messenger signalling in excitable cells. In the heart, rapid summation of the elementary events of calcium release, 'calcium sparks', determine the contraction of the myocardium. We adapted a correlative super-resolution microscopy protocol to correlate sub-plasmalemmal spontaneous calcium sparks in rat right ventricular myocytes with the local nanoscale RyR2 positions. This revealed a steep relationship between the integral of a calcium spark and the sum of the local RyR2s. Segmentation of recurring spark sites showed evidence of repeated and triggered saltatory activation of multiple local RyR2 clusters. In myocytes taken from failing right ventricles, RyR2 clusters themselves showed a dissipated morphology and fragmented (smaller) clusters. They also featured greater heterogeneity in both the spark properties and the relationship between the integral of the calcium spark and the local ensemble of RyR2s. While fragmented (smaller) RyR2 clusters were rarely observed directly underlying the larger sparks or the recurring spark sites, local interrogation of the channel-to-channel distances confirmed a clear link between the positions of each calcium spark and the tight, non-random clustering of the local RyR2 in both healthy and failing ventricles.
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Affiliation(s)
- Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas M. D. Sheard
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
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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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35
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Pereira L, Val-Blasco A, Benitah JP, Gómez AM. Profiling the Ca +2 sparks dynamics in live cardiomyocytes. NATURE CARDIOVASCULAR RESEARCH 2023; 2:225-226. [PMID: 38774914 PMCID: PMC11108056 DOI: 10.1038/s44161-022-00203-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2024]
Affiliation(s)
- Laetitia Pereira
- Inserm, UMR-S 1180, “Signaling and Cardiovascular Pathophysiology”, Université Paris-Saclay, 91400 Orsay, France
| | - Almudena Val-Blasco
- Inserm, UMR-S 1180, “Signaling and Cardiovascular Pathophysiology”, Université Paris-Saclay, 91400 Orsay, France
| | - Jean-Pierre Benitah
- Inserm, UMR-S 1180, “Signaling and Cardiovascular Pathophysiology”, Université Paris-Saclay, 91400 Orsay, France
| | - Ana M Gómez
- Inserm, UMR-S 1180, “Signaling and Cardiovascular Pathophysiology”, Université Paris-Saclay, 91400 Orsay, France
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36
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Dvinskikh L, Sparks H, MacLeod KT, Dunsby C. High-speed 2D light-sheet fluorescence microscopy enables quantification of spatially varying calcium dynamics in ventricular cardiomyocytes. Front Physiol 2023; 14:1079727. [PMID: 36866170 PMCID: PMC9971815 DOI: 10.3389/fphys.2023.1079727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/27/2023] [Indexed: 02/16/2023] Open
Abstract
Introduction: Reduced synchrony of calcium release and t-tubule structure organization in individual cardiomyocytes has been linked to loss of contractile strength and arrhythmia. Compared to confocal scanning techniques widely used for imaging calcium dynamics in cardiac muscle cells, light-sheet fluorescence microscopy enables fast acquisition of a 2D plane in the sample with low phototoxicity. Methods: A custom light-sheet fluorescence microscope was used to achieve dual-channel 2D timelapse imaging of calcium and the sarcolemma, enabling calcium sparks and transients in left and right ventricle cardiomyocytes to be correlated with the cell microstructure. Imaging electrically stimulated dual-labelled cardiomyocytes immobilized with para-nitroblebbistatin, a non-phototoxic, low fluorescence contraction uncoupler, with sub-micron resolution at 395 fps over a 38 μm × 170 µm FOV allowed characterization of calcium spark morphology and 2D mapping of the calcium transient time-to-half-maximum across the cell. Results: Blinded analysis of the data revealed sparks with greater amplitude in left ventricle myocytes. The time for the calcium transient to reach half-maximum amplitude in the central part of the cell was found to be, on average, 2 ms shorter than at the cell ends. Sparks co-localized with t-tubules were found to have significantly longer duration, larger area and spark mass than those further away from t-tubules. Conclusion: The high spatiotemporal resolution of the microscope and automated image-analysis enabled detailed 2D mapping and quantification of calcium dynamics of n = 60 myocytes, with the findings demonstrating multi-level spatial variation of calcium dynamics across the cell, supporting the dependence of synchrony and characteristics of calcium release on the underlying t-tubule structure.
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Affiliation(s)
- Liuba Dvinskikh
- Department of Physics, Imperial College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Hugh Sparks
- Department of Physics, Imperial College London, London, United Kingdom
| | - Kenneth T. MacLeod
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Chris Dunsby
- Department of Physics, Imperial College London, London, United Kingdom
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37
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Yang Z, Koslover EF. Diffusive exit rates through pores in membrane-enclosed structures. Phys Biol 2023; 20. [PMID: 36626849 DOI: 10.1088/1478-3975/acb1ea] [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: 10/27/2022] [Accepted: 01/10/2023] [Indexed: 01/11/2023]
Abstract
The function of many membrane-enclosed intracellular structures relies on release of diffusing particles that exit through narrow pores or channels in the membrane. The rate of release varies with pore size, density, and length of the channel. We propose a simple approximate model, validated with stochastic simulations, for estimating the effective release rate from cylinders, and other simple-shaped domains, as a function of channel parameters. The results demonstrate that, for very small pores, a low density of channels scattered over the boundary is sufficient to achieve substantial rates of particle release. Furthermore, we show that increasing the length of passive channels will both reduce release rates and lead to a less steep dependence on channel density. Our results are compared to previously-measured local calcium release rates from tubules of the endoplasmic reticulum, providing an estimate of the relevant channel density responsible for the observed calcium efflux.
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Affiliation(s)
- Zitao Yang
- La Jolla Country Day School, La Jolla, CA 92037, United States of America
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, United States of America
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38
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Reyes Gaido OE, Nkashama LJ, Schole KL, Wang Q, Umapathi P, Mesubi OO, Konstantinidis K, Luczak ED, Anderson ME. CaMKII as a Therapeutic Target in Cardiovascular Disease. Annu Rev Pharmacol Toxicol 2023; 63:249-272. [PMID: 35973713 PMCID: PMC11019858 DOI: 10.1146/annurev-pharmtox-051421-111814] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
CaMKII (the multifunctional Ca2+ and calmodulin-dependent protein kinase II) is a highly validated signal for promoting a variety of common diseases, particularly in the cardiovascular system. Despite substantial amounts of convincing preclinical data, CaMKII inhibitors have yet to emerge in clinical practice. Therapeutic inhibition is challenged by the diversity of CaMKII isoforms and splice variants and by physiological CaMKII activity that contributes to learning and memory. Thus, uncoupling the harmful and beneficial aspects of CaMKII will be paramount to developing effective therapies. In the last decade, several targeting strategies have emerged, including small molecules, peptides, and nucleotides, which hold promise in discriminating pathological from physiological CaMKII activity. Here we review the cellular and molecular biology of CaMKII, discuss its role in physiological and pathological signaling, and consider new findings and approaches for developing CaMKII therapeutics.
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Affiliation(s)
- Oscar E Reyes Gaido
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | | | - Kate L Schole
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Qinchuan Wang
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Priya Umapathi
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Olurotimi O Mesubi
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Klitos Konstantinidis
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Elizabeth D Luczak
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
| | - Mark E Anderson
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA;
- Departments of Physiology and Genetic Medicine and Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Chung J, Tilūnaitė A, Ladd D, Hunt H, Soeller C, Crampin EJ, Johnston ST, Roderick HL, Rajagopal V. IP 3R activity increases propensity of RyR-mediated sparks by elevating dyadic [Ca 2+]. Math Biosci 2023; 355:108923. [PMID: 36395827 DOI: 10.1016/j.mbs.2022.108923] [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: 05/31/2022] [Revised: 10/15/2022] [Accepted: 10/15/2022] [Indexed: 11/16/2022]
Abstract
Calcium (Ca2+) plays a critical role in the excitation contraction coupling (ECC) process that mediates the contraction of cardiomyocytes during each heartbeat. While ryanodine receptors (RyRs) are the primary Ca2+ channels responsible for generating the cell-wide Ca2+ transients during ECC, Ca2+ release, via inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) are also reported in cardiomyocytes to elicit ECC-modulating effects. Recent studies suggest that the localization of IP3Rs at dyads grant their ability to modify the occurrence of Ca2+ sparks (elementary Ca2+ release events that constitute cell wide Ca2+ releases associated with ECC) which may underlie their modulatory influence on ECC. Here, we aim to uncover the mechanism by which dyad-localized IP3Rs influence Ca2+ spark dynamics. To this end, we developed a mathematical model of the dyad that incorporates the behaviour of IP3Rs, in addition to RyRs, to reveal the impact of their activity on local Ca2+ handling and consequent Ca2+ spark occurrence and its properties. Consistent with published experimental data, our model predicts that the propensity for Ca2+ spark formation increases in the presence of IP3R activity. Our simulations support the hypothesis that IP3Rs elevate Ca2+ in the dyad, sensitizing proximal RyRs towards activation and hence Ca2+ spark formation. The stochasticity of IP3R gating is an important aspect of this mechanism. However, dyadic IP3R activity lowers the Ca2+ available in the junctional sarcoplasmic reticulum (JSR) for release, thus resulting in Ca2+ sparks with similar durations but lower amplitudes.
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Affiliation(s)
- Joshua Chung
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000, Leuven, Belgium
| | - Agnė Tilūnaitė
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - David Ladd
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC 3010, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, School of Chemical and Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Hilary Hunt
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Edmund J Crampin
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC 3010, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, School of Chemical and Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Stuart T Johnston
- School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC 3010, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, School of Chemical and Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, 3000, Leuven, Belgium.
| | - Vijay Rajagopal
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Melbourne, VIC 3010, Australia.
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40
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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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41
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Shkryl VM. The spatio-temporal properties of calcium transients in hippocampal pyramidal neurons in vitro. Front Cell Neurosci 2022; 16:1054950. [PMID: 36589284 PMCID: PMC9795003 DOI: 10.3389/fncel.2022.1054950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/24/2022] [Indexed: 12/15/2022] Open
Abstract
The spatio-temporal properties of calcium signals were studied in cultured pyramidal neurons of the hippocampus using two-dimensional fluorescence microscopy and ratiometric dye Fura-2. Depolarization-induced Ca2+ transients revealed an asynchronous delayed increase in free Ca2+ concentration. We found that the level of free resting calcium in the cell nucleus is significantly lower compared to the soma, sub-membrane, and dendritic tree regions. Calcium release from the endoplasmic reticulum under the action of several stimuli (field stimulation, high K+ levels, and caffeine) occurs in all areas studied. Under depolarization, calcium signals developed faster in the dendrites than in other areas, while their amplitude was significantly lower since larger and slower responses inside the soma. The peak value of the calcium response to the application of 10 mM caffeine, ryanodine receptors (RyRs) agonist, does not differ in the sub-membrane zone, central region, and nucleus but significantly decreases in the dendrites. In the presence of caffeine, the delay of Ca2+ signals between various areas under depolarization significantly declined. Thirty percentage of the peak amplitude of Ca2+ transients at prolonged electric field stimulation corresponded to calcium release from the ER store by RyRs, while short-term stimulation did not depend on them. 20 μM dantrolene, RyRs inhibitor, significantly reduces Ca2+ transient under high K+ levels depolarization of the neuron. RyRs-mediated enhancement of the Ca2+ signal is more pronounced in the central part and nucleus compared to the sub-membrane or dendrites regions of the neuron. In summary, using the ratiometric imaging allowed us to obtain additional information about the involvement of RyRs in the intracellular dynamics of Ca2+ signals induced by depolarization or electrical stimulation train, with an underlying change in Ca2+ concentration in various regions of interest in hippocampal pyramidal neurons.
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42
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Tang N, Tian W, Ma GY, Xiao X, Zhou L, Li ZZ, Liu XX, Li CY, Wu KH, Liu W, Wang XY, Gao YY, Yang X, Qi J, Li D, Liu Y, Chen WS, Gao J, Li XQ, Cao W. TRPC channels blockade abolishes endotoxemic cardiac dysfunction by hampering intracellular inflammation and Ca 2+ leakage. Nat Commun 2022; 13:7455. [PMID: 36460692 PMCID: PMC9718841 DOI: 10.1038/s41467-022-35242-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/23/2022] [Indexed: 12/04/2022] Open
Abstract
Intracellular Ca2+ dysregulation is a key marker in septic cardiac dysfunction; however, regulation of the classic Ca2+ regulatory modules cannot successfully abolish this symptom. Here we show that the knockout of transient receptor potential canonical (TRPC) channel isoforms TRPC1 and TRPC6 can ameliorate LPS-challenged heart failure and prolong survival in mice. The LPS-triggered Ca2+ release from the endoplasmic reticulum both in cardiomyocytes and macrophages is significantly inhibited by Trpc1 or Trpc6 knockout. Meanwhile, TRPC's molecular partner - calmodulin - is uncoupled during Trpc1 or Trpc6 deficiency and binds to TLR4's Pococurante site and atypical isoleucine-glutamine-like motif to block the inflammation cascade. Blocking the C-terminal CaM/IP3R binding domain in TRPC with chemical inhibitor could obstruct the Ca2+ leak and TLR4-mediated inflammation burst, demonstrating a cardioprotective effect in endotoxemia and polymicrobial sepsis. Our findings provide insight into the pathogenesis of endotoxemic cardiac dysfunction and suggest a novel approach for its treatment.
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Affiliation(s)
- Na Tang
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Wen Tian
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Guang-Yuan Ma
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiong Xiao
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Lei Zhou
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Ze-Zhi Li
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiao-Xiao Liu
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Chong-Yao Li
- grid.412262.10000 0004 1761 5538Department of Pharmacy, Xi’an No.3 Hospital, the Affiliated Hospital of Northwest University, Xi’an, Shaanxi China
| | - Ke-Han Wu
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Wenjuan Liu
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China
| | - Xue-Ying Wang
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Yuan-Yuan Gao
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Xin Yang
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Jianzhao Qi
- grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Ding Li
- grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Yang Liu
- grid.233520.50000 0004 1761 4404Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Wen-Sheng Chen
- grid.233520.50000 0004 1761 4404Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi China ,Department of Cardiovascular Surgery, Xi’an Gaoxin Hospital, Xi’an, Shaanxi China
| | - Jinming Gao
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiao-Qiang Li
- grid.233520.50000 0004 1761 4404Department of Pharmacology, School of Pharmacy, Fourth Military Medical University, Xi’an, Shaanxi China ,grid.233520.50000 0004 1761 4404Key Laboratory of Gastrointestinal Pharmacology of Chinese Materia Medica of the State Administration of Traditional Chinese Medicine, Fourth Military Medical University, Xi’an, Shaanxi China
| | - Wei Cao
- grid.144022.10000 0004 1760 4150Department of Pharmacy, School of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi China ,grid.144022.10000 0004 1760 4150Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, Yangling, Shaanxi China
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Ryvkin AM, Markov NS, Yudenko V. Calcium Sparks in Cardiac Pacemaker Cells at Different Temperatures in silico. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022070134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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44
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Nagy N, Tóth N, Nánási PP. Antiarrhythmic and Inotropic Effects of Selective Na +/Ca 2+ Exchanger Inhibition: What Can We Learn from the Pharmacological Studies? Int J Mol Sci 2022; 23:ijms232314651. [PMID: 36498977 PMCID: PMC9736231 DOI: 10.3390/ijms232314651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022] Open
Abstract
Life-long stable heart function requires a critical balance of intracellular Ca2+. Several ion channels and pumps cooperate in a complex machinery that controls the influx, release, and efflux of Ca2+. Probably one of the most interesting and most complex players of this crosstalk is the Na+/Ca2+ exchanger, which represents the main Ca2+ efflux mechanism; however, under some circumstances, it can also bring Ca2+ into the cell. Therefore, the inhibition of the Na+/Ca2+ exchanger has emerged as one of the most promising possible pharmacological targets to increase Ca2+ levels, to decrease arrhythmogenic depolarizations, and to reduce excessive Ca2+ influx. In line with this, as a response to increasing demand, several more or less selective Na+/Ca2+ exchanger inhibitor compounds have been developed. In the past 20 years, several results have been published regarding the effect of Na+/Ca2+ exchanger inhibition under various circumstances, e.g., species, inhibitor compounds, and experimental conditions; however, the results are often controversial. Does selective Na+/Ca2+ exchanger inhibition have any future in clinical pharmacological practice? In this review, the experimental results of Na+/Ca2+ exchanger inhibition are summarized focusing on the data obtained by novel highly selective inhibitors.
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Affiliation(s)
- Norbert Nagy
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
- Correspondence: ; Tel.: +36-62-545-682; Fax: +36-62-545-680
| | - Noémi Tóth
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
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45
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Fisher ES, Chen Y, Sifuentes MM, Stubblefield JJ, Lozano D, Holstein DM, Ren J, Davenport M, DeRosa N, Chen TP, Nickel G, Liston TE, Lechleiter JD. Adenosine A1R/A3R agonist AST-004 reduces brain infarction in mouse and rat models of acute ischemic stroke. FRONTIERS IN STROKE 2022; 1:1010928. [PMID: 38348128 PMCID: PMC10861240 DOI: 10.3389/fstro.2022.1010928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
Acute ischemic stroke (AIS) is the second leading cause of death globally. No Food and Drug Administration (FDA) approved therapies exist that target cerebroprotection following stroke. Our group recently reported significant cerebroprotection with the adenosine A1/A3 receptor agonist, AST-004, in a transient stroke model in non-human primates (NHP) and in a preclinical mouse model of traumatic brain injury (TBI). However, the specific receptor pathway activated was only inferred based on in vitro binding studies. The current study investigated the underlying mechanism of AST-004 cerebroprotection in two independent models of AIS: permanent photothrombotic stroke in mice and transient middle cerebral artery occlusion (MCAO) in rats. AST-004 treatments across a range of doses were cerebroprotective and efficacy could be blocked by A3R antagonism, indicating a mechanism of action that does not require A1R agonism. The high affinity A3R agonist MRS5698 was also cerebroprotective following stroke, but not the A3R agonist Cl-IB-MECA under our experimental conditions. AST-004 efficacy was blocked by the astrocyte specific mitochondrial toxin fluoroacetate, confirming an underlying mechanism of cerebroprotection that was dependent on astrocyte mitochondrial metabolism. An increase in A3R mRNA levels following stroke suggested an intrinsic cerebroprotective response that was mediated by A3R signaling. Together, these studies confirm that certain A3R agonists, such as AST-004, may be exciting new therapeutic avenues to develop for AIS.
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Affiliation(s)
- Elizabeth S. Fisher
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Yanan Chen
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Mikaela M. Sifuentes
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Jeremy J. Stubblefield
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Damian Lozano
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Deborah M. Holstein
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - JingMei Ren
- NeuroVasc Preclinical Services, Inc., Lexington, MA, United States
| | | | - Nicholas DeRosa
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Tsung-pei Chen
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | - Gerard Nickel
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
| | | | - James D. Lechleiter
- Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, United States
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Sheard TMD, Hurley ME, Smith AJ, Colyer J, White E, Jayasinghe I. Three-dimensional visualization of the cardiac ryanodine receptor clusters and the molecular-scale fraying of dyads. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210316. [PMID: 36189802 PMCID: PMC9527906 DOI: 10.1098/rstb.2021.0316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/11/2022] [Indexed: 11/12/2022] Open
Abstract
Clusters of ryanodine receptor calcium channels (RyRs) form the primary molecular machinery of intracellular calcium signalling in cardiomyocytes. While a range of optical super-resolution microscopy techniques have revealed the nanoscale structure of these clusters, the three-dimensional (3D) nanoscale topologies of the clusters have remained mostly unresolved. In this paper, we demonstrate the exploitation of molecular-scale resolution in enhanced expansion microscopy (EExM) along with various 2D and 3D visualization strategies to observe the topological complexities, geometries and molecular sub-domains within the RyR clusters. Notably, we observed sub-domains containing RyR-binding protein junctophilin-2 (JPH2) occupying the central regions of RyR clusters in the deeper interior of the myocytes (including dyads), while the poles were typically devoid of JPH2, lending to a looser RyR arrangement. By contrast, peripheral RyR clusters exhibited variable co-clustering patterns and ratios between RyR and JPH2. EExM images of dyadic RyR clusters in right ventricular (RV) myocytes isolated from rats with monocrotaline-induced RV failure revealed hallmarks of RyR cluster fragmentation accompanied by breaches in the JPH2 sub-domains. Frayed RyR patterns observed adjacent to these constitute new evidence that the destabilization of the RyR arrays inside the JPH2 sub-domains may seed the primordial foci of dyad remodelling observed in heart failure. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Thomas M. D. Sheard
- School of Biosciences, Faculty of Science, University of Sheffield, Sheffield S10 2TN, UK
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew J. Smith
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - John Colyer
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, University of Sheffield, Sheffield S10 2TN, UK
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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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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Si D, Chakraborty P, Azam MA, Nair MKK, Massé S, Lai PF, Labos C, Riazi S, Nanthakumar K. Synchronizing systolic calcium release with azumolene in an experimental model. Heart Rhythm O2 2022; 3:568-576. [PMID: 36340488 PMCID: PMC9626747 DOI: 10.1016/j.hroo.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background Post-defibrillation myocardial contractile dysfunction adversely affects the survival of patients after cardiac arrest. Attenuation of diastolic calcium (Ca2+) overload by stabilization of the cardiac ryanodine receptor (RyR2) is found to reduce refibrillation after long-duration ventricular fibrillation (LDVF). Objective In the present study, we explored the effects of RyR2 stabilization by azumolene on systolic Ca2+ release synchrony and myocardial contractility. Methods After completion of baseline optical mapping, Langendorff-perfused rabbit hearts were subjected to global ischemia followed by reperfusion with azumolene or deionized distilled water (vehicle). Following reperfusion, LDVF was induced with burst pacing. In the first series of experiments (n = 16), epicardial Ca2+ transient was analyzed for Ca2+ transient amplitude alternans and dispersion of Ca2+ transient amplitude alternans index (CAAI). In the second series of experiments following the same protocol (n = 12), ventricular contractility was assessed by measuring the left ventricular pressure. Results Ischemic LDVF led to greater CAAI (0.06 ± 0.02 at baseline vs 0.12 ± 0.02 post-LDVF, P < .01) and magnitude of dispersion of CAAI (0.04 ± 0.01 vs 0.09 ± 0.01, P < .01) in control hearts. In azumolene-treated hearts, no significant changes in CAAI (0.05 ± 0.01 vs 0.05 ± 0.01, P = .84) and dispersion of CAAI (0.04 ± 0.01 vs 0.04 ± 0.01, P = .99) were noted following ischemic LDVF. Ischemic LDVF was associated with reduction in left ventricular developed pressure (100% vs 36.8% ± 6.1%, P = .002) and dP/dtmax (100% vs 45.3% ± 6.5%, P = .003) in control hearts, but these reductions were mitigated (left ventricular developed pressure: 100% vs 74.0% ± 8.1%, P = .052, dP/dtmax: 100% vs 80.8% ± 7.9%, P = .09) in azumolene-treated hearts. Conclusion Treatment with azumolene is associated with improvement of systolic Ca2+ release synchrony and myocardial contractility following ischemic LDVF.
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Affiliation(s)
- Daoyuan Si
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
- Department of Cardiology, China-Japan Union Hospital, Jilin University, Changchun, China
| | - Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Madhav Krishna Kumar Nair
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Patrick F.H. Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | | | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia and Pain Management, University Health Network, Toronto, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
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49
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Abstract
The global burden caused by cardiovascular disease is substantial, with heart disease representing the most common cause of death around the world. There remains a need to develop better mechanistic models of cardiac function in order to combat this health concern. Heart rhythm disorders, or arrhythmias, are one particular type of disease which has been amenable to quantitative investigation. Here we review the application of quantitative methodologies to explore dynamical questions pertaining to arrhythmias. We begin by describing single-cell models of cardiac myocytes, from which two and three dimensional models can be constructed. Special focus is placed on results relating to pattern formation across these spatially-distributed systems, especially the formation of spiral waves of activation. Next, we discuss mechanisms which can lead to the initiation of arrhythmias, focusing on the dynamical state of spatially discordant alternans, and outline proposed mechanisms perpetuating arrhythmias such as fibrillation. We then review experimental and clinical results related to the spatio-temporal mapping of heart rhythm disorders. Finally, we describe treatment options for heart rhythm disorders and demonstrate how statistical physics tools can provide insights into the dynamics of heart rhythm disorders.
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Affiliation(s)
- Wouter-Jan Rappel
- Department of Physics, University of California San Diego, La Jolla, CA 92037
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50
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Rupee S, Rupee K, Singh RB, Hanoman C, Ismail AMA, Smail M, Singh J. Diabetes-induced chronic heart failure is due to defects in calcium transporting and regulatory contractile proteins: cellular and molecular evidence. Heart Fail Rev 2022; 28:627-644. [PMID: 36107271 DOI: 10.1007/s10741-022-10271-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/07/2022] [Indexed: 11/04/2022]
Abstract
Heart failure (HF) is a major deteriorating disease of the myocardium due to weak myocardial muscles. As such, the heart is unable to pump blood efficiently around the body to meet its constant demand. HF is a major global health problem with more than 7 million deaths annually worldwide, with some patients dying suddenly due to sudden cardiac death (SCD). There are several risk factors which are associated with HF and SCD which can negatively affect the heart synergistically. One major risk factor is diabetes mellitus (DM) which can cause an elevation in blood glucose level or hyperglycaemia (HG) which, in turn, has an insulting effect on the myocardium. This review attempted to explain the subcellular, cellular and molecular mechanisms and to a lesser extent, the genetic factors associated with the development of diabetes- induced cardiomyopathy due to the HG which can subsequently lead to chronic heart failure (CHF) and SCD. The study first explained the structure and function of the myocardium and then focussed mainly on the excitation-contraction coupling (ECC) processes highlighting the defects of calcium transporting (SERCA, NCX, RyR and connexin) and contractile regulatory (myosin, actin, titin and troponin) proteins. The study also highlighted new therapies and those under development, as well as preventative strategies to either treat or prevent diabetic cardiomyopathy (DCM). It is postulated that prevention is better than cure.
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