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Røsand Ø, Wang J, Scrimgeour N, Marwarha G, Høydal MA. Exosomal Preconditioning of Human iPSC-Derived Cardiomyocytes Beneficially Alters Cardiac Electrophysiology and Micro RNA Expression. Int J Mol Sci 2024; 25:8460. [PMID: 39126028 PMCID: PMC11313350 DOI: 10.3390/ijms25158460] [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: 06/13/2024] [Revised: 07/27/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Experimental evidence, both in vitro and in vivo, has indicated cardioprotective effects of extracellular vesicles (EVs) derived from various cell types, including induced pluripotent stem cell-derived cardiomyocytes. The biological effects of EV secretion, particularly in the context of ischemia and cardiac electrophysiology, remain to be fully explored. Therefore, the goal of this study was to unveil the effects of exosome (EXO)-mediated cell-cell signaling during hypoxia by employing a simulated preconditioning approach on human-induced pluripotent stem cell-derived cardiomyocytes (hIPSC-CMs). Electrophysiological activity of hIPSC-CMs was measured using a multielectrode array (MEA) system. A total of 16 h of hypoxic stress drastically increased the beat period. Moreover, hIPSC-CMs preconditioned with EXOs displayed significantly longer beat periods compared with non-treated cells after 16 h of hypoxia (+15.7%, p < 0.05). Furthermore, preconditioning with hypoxic EXOs resulted in faster excitation-contraction (EC) coupling compared with non-treated hIPSC-CMs after 16 h of hypoxia (-25.3%, p < 0.05). Additionally, microRNA (miR) sequencing and gene target prediction analysis of the non-treated and pre-conditioned hIPSC-CMs identified 10 differentially regulated miRs and 44 gene targets. These results shed light on the intricate involvement of miRs, emphasizing gene targets associated with cell survival, contraction, apoptosis, reactive oxygen species (ROS) regulation, and ion channel modulation. Overall, this study demonstrates that EXOs secreted by hIPSC-CM during hypoxia beneficially alter electrophysiological properties in recipient cells exposed to hypoxic stress, which could play a crucial role in the development of targeted interventions to improve outcomes in ischemic heart conditions.
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Affiliation(s)
| | | | | | | | - Morten Andre Høydal
- Group of Molecular and Cellular Cardiology, Department of Circulation and Medical Imaging, Faculty of Medicine and Health, Norwegian University of Science and Technology (NTNU), 7030 Trondheim, Norway; (Ø.R.); (J.W.); (N.S.); (G.M.)
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Kameyama M, Minobe E, Shao D, Xu J, Gao Q, Hao L. Regulation of Cardiac Cav1.2 Channels by Calmodulin. Int J Mol Sci 2023; 24:ijms24076409. [PMID: 37047381 PMCID: PMC10094977 DOI: 10.3390/ijms24076409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/19/2023] [Accepted: 03/23/2023] [Indexed: 03/31/2023] Open
Abstract
Cav1.2 Ca2+ channels, a type of voltage-gated L-type Ca2+ channel, are ubiquitously expressed, and the predominant Ca2+ channel type, in working cardiac myocytes. Cav1.2 channels are regulated by the direct interactions with calmodulin (CaM), a Ca2+-binding protein that causes Ca2+-dependent facilitation (CDF) and inactivation (CDI). Ca2+-free CaM (apoCaM) also contributes to the regulation of Cav1.2 channels. Furthermore, CaM indirectly affects channel activity by activating CaM-dependent enzymes, such as CaM-dependent protein kinase II and calcineurin (a CaM-dependent protein phosphatase). In this article, we review the recent progress in identifying the role of apoCaM in the channel ‘rundown’ phenomena and related repriming of channels, and CDF, as well as the role of Ca2+/CaM in CDI. In addition, the role of CaM in channel clustering is reviewed.
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Affiliation(s)
- Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
- Correspondence:
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Dongxue Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Qinghua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
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Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIδ autophosphorylation and L-type calcium channel inactivation. J Biol Chem 2023; 299:102777. [PMID: 36496072 PMCID: PMC9830374 DOI: 10.1016/j.jbc.2022.102777] [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: 07/28/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022] Open
Abstract
Long QT syndrome (LQTS) is a human inherited heart condition that can cause life-threatening arrhythmia including sudden cardiac death. Mutations in the ubiquitous Ca2+-sensing protein calmodulin (CaM) are associated with LQTS, but the molecular mechanism by which these mutations lead to irregular heartbeats is not fully understood. Here, we use a multidisciplinary approach including protein biophysics, structural biology, confocal imaging, and patch-clamp electrophysiology to determine the effect of the disease-associated CaM mutation E140G on CaM structure and function. We present novel data showing that mutant-regulated CaMKIIδ kinase activity is impaired with a significant reduction in enzyme autophosphorylation rate. We report the first high-resolution crystal structure of a LQTS-associated CaM variant in complex with the CaMKIIδ peptide, which shows significant structural differences, compared to the WT complex. Furthermore, we demonstrate that the E140G mutation significantly disrupted Cav1.2 Ca2+/CaM-dependent inactivation, while cardiac ryanodine receptor (RyR2) activity remained unaffected. In addition, we show that the LQTS-associated mutation alters CaM's Ca2+-binding characteristics, secondary structure content, and interaction with key partners involved in excitation-contraction coupling (CaMKIIδ, Cav1.2, RyR2). In conclusion, LQTS-associated CaM mutation E140G severely impacts the structure-function relationship of CaM and its regulation of CaMKIIδ and Cav1.2. This provides a crucial insight into the molecular factors contributing to CaM-mediated arrhythmias with a central role for CaMKIIδ.
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Beghi S, Furmanik M, Jaminon A, Veltrop R, Rapp N, Wichapong K, Bidar E, Buschini A, Schurgers LJ. Calcium Signalling in Heart and Vessels: Role of Calmodulin and Downstream Calmodulin-Dependent Protein Kinases. Int J Mol Sci 2022; 23:ijms232416139. [PMID: 36555778 PMCID: PMC9783221 DOI: 10.3390/ijms232416139] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Cardiovascular disease is the major cause of death worldwide. The success of medication and other preventive measures introduced in the last century have not yet halted the epidemic of cardiovascular disease. Although the molecular mechanisms of the pathophysiology of the heart and vessels have been extensively studied, the burden of ischemic cardiovascular conditions has risen to become a top cause of morbidity and mortality. Calcium has important functions in the cardiovascular system. Calcium is involved in the mechanism of excitation-contraction coupling that regulates numerous events, ranging from the production of action potentials to the contraction of cardiomyocytes and vascular smooth muscle cells. Both in the heart and vessels, the rise of intracellular calcium is sensed by calmodulin, a protein that regulates and activates downstream kinases involved in regulating calcium signalling. Among them is the calcium calmodulin kinase family, which is involved in the regulation of cardiac functions. In this review, we present the current literature regarding the role of calcium/calmodulin pathways in the heart and vessels with the aim to summarize our mechanistic understanding of this process and to open novel avenues for research.
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Affiliation(s)
- Sofia Beghi
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 11A, 43124 Parma, Italy
- Correspondence: ; Tel.: +39-3408473527
| | - Malgorzata Furmanik
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Armand Jaminon
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Rogier Veltrop
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Nikolas Rapp
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Kanin Wichapong
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Elham Bidar
- Department of Cardiothoracic Surgery, Heart and Vascular Centre, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands
| | - Annamaria Buschini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 11A, 43124 Parma, Italy
| | - Leon J. Schurgers
- Cardiovascular Research Institute Maastricht (CARIM), Department of Biochemistry, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
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Jorgensen AN, Abdullah CS, Bhuiyan MS, Watt M, Dominic P, Kolluru GK, Kevil CG, Nam HW. Neurogranin regulates calcium-dependent cardiac hypertrophy. Exp Mol Pathol 2022; 127:104815. [PMID: 35870494 PMCID: PMC11118017 DOI: 10.1016/j.yexmp.2022.104815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 04/15/2022] [Accepted: 07/16/2022] [Indexed: 11/04/2022]
Abstract
Intracellular Ca2+-calmodulin (CaM) signaling plays an important role in Ca2+-CaM-dependent kinase (CaMKII) and calcineurin (CaN)-mediated cardiac biology. While neurogranin (Ng) is known as a major Ca2+-CaM modulator in the brain, its pathophysiological role in cardiac hypertrophy has never been studied before. In the present study, we report that Ng is expressed in the heart and depletion of Ng dysregulates Ca2+ homeostasis and promotes cardiac failure in mice. 10-month-old Ng null mice demonstrate significantly increased heart-to-body weight ratios compared to wild-type. Using histological approaches, we identified that depletion of Ng increases cardiac hypertrophy, fibrosis, and collagen deposition near perivascular areas in the heart tissue of Ng null mice. Ca2+ spark experiments revealed that cardiac myocytes isolated from Ng null mice have decreased spark frequency and width, while the duration of sparks is significantly increased. We also identified that a lack of Ng increases CaMKIIδ signaling and periostin protein expression in these mouse hearts. Overall, we are the first study to explore how Ng expression in the heart plays an important role in Ca2+ homeostasis in cardiac myocytes as well as the pathophysiology of cardiac hypertrophy and fibrosis.
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Affiliation(s)
- Ashton N Jorgensen
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Chowdhury S Abdullah
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Md Shenuarin Bhuiyan
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Megan Watt
- Devision of Cardiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Paari Dominic
- Devision of Cardiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Gopi K Kolluru
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Christopher G Kevil
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America
| | - Hyung W Nam
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA 71130, United States of America.
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Prakash O, Held M, McCormick LF, Gupta N, Lian LY, Antonyuk S, Haynes LP, Thomas NL, Helassa N. CPVT-associated calmodulin variants N53I and A102V dysregulate Ca2+ signalling via different mechanisms. J Cell Sci 2022; 135:274029. [PMID: 34888671 PMCID: PMC8917356 DOI: 10.1242/jcs.258796] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 11/29/2021] [Indexed: 12/26/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited condition that can cause fatal cardiac arrhythmia. Human mutations in the Ca2+ sensor calmodulin (CaM) have been associated with CPVT susceptibility, suggesting that CaM dysfunction is a key driver of the disease. However, the detailed molecular mechanism remains unclear. Focusing on the interaction with the cardiac ryanodine receptor (RyR2), we determined the effect of CPVT-associated variants N53I and A102V on the structural characteristics of CaM and on Ca2+ fluxes in live cells. We provide novel data showing that interaction of both Ca2+/CaM-N53I and Ca2+/CaM-A102V with the RyR2 binding domain is decreased. Ca2+/CaM-RyR23583-3603 high-resolution crystal structures highlight subtle conformational changes for the N53I variant, with A102V being similar to wild type (WT). We show that co-expression of CaM-N53I or CaM-A102V with RyR2 in HEK293 cells significantly increased the duration of Ca2+ events; CaM-A102V exhibited a lower frequency of Ca2+ oscillations. In addition, we show that CaMKIIδ (also known as CAMK2D) phosphorylation activity is increased for A102V, compared to CaM-WT. This paper provides novel insight into the molecular mechanisms of CPVT-associated CaM variants and will facilitate the development of strategies for future therapies.
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Affiliation(s)
- Ohm Prakash
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Marie Held
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Liam F. McCormick
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Nitika Gupta
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Lu-Yun Lian
- Nuclear Magnetic Resonance Centre for Structural Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Svetlana Antonyuk
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Lee P. Haynes
- Department of Molecular Physiology and Cell Signalling, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - N. Lowri Thomas
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Cardiff, Redwood Building, CF10 3NB, UK
| | - Nordine Helassa
- Liverpool Centre for Cardiovascular Science, Department of Cardiovascular Science and Metabolic Medicine, Institute of Life Course and Medical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3BX, UK,Author for correspondence ()
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Sun Y, Zhu B, Ling S, Yan B, Wang X, Jia S, Martyniuk CJ, Zhang W, Yang L, Zhou B. Decabromodiphenyl Ethane Mainly Affected the Muscle Contraction and Reproductive Endocrine System in Female Adult Zebrafish. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:470-479. [PMID: 34919388 DOI: 10.1021/acs.est.1c06679] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The novel brominated flame retardant decabromodiphenyl ethane (DBDPE) has become a widespread environmental pollutant. However, the target tissue and toxicity of DBDPE are still not clear. In the current study, female zebrafish were exposed to 1 and 100 nM DBDPE for 28 days. Chemical analysis revealed that DBDPE tended to accumulate in the brain other than the liver and gonad. Subsequently, tandem mass tag-based quantitative proteomics and parallel reaction monitoring verification were performed to screen the differentially expressed proteins in the brain. Bioinformatics analysis revealed that DBDPE mainly affected the biological process related to muscle contraction and estrogenic response. Therefore, the neurotoxicity and reproductive disruptions were validated via multilevel toxicological endpoints. Specifically, locomotor behavioral changes proved the potency of neurotoxicity, which may be caused by disturbance of muscular proteins and calcium homeostasis; decreases of sex hormone levels and transcriptional changes of genes related to the hypothalamic-pituitary-gonad-liver axis confirmed reproductive disruptions upon DBDPE exposure. In summary, our results suggested that DBDPE primarily accumulated in the brain and evoked neurotoxicity and reproductive disruptions in female zebrafish. These findings can provide important clues for a further mechanism study and risk assessment of DBDPE.
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Affiliation(s)
- Yumiao Sun
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Biran Zhu
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Siyuan Ling
- Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Biao Yan
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiulin Wang
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuzhao Jia
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Christopher J Martyniuk
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida Genetics Institute, Interdisciplinary Program in Biomedical Sciences Neuroscience, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611 United States
| | - Wei Zhang
- Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Lihua Yang
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Bingsheng Zhou
- Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
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McDonough RC, Price C. Targeted Activation of GPCR-Mediated Ca 2+ Signaling Drives Enhanced Cartilage-Like Matrix Formation. Tissue Eng Part A 2021; 28:405-419. [PMID: 34693731 PMCID: PMC9271335 DOI: 10.1089/ten.tea.2021.0078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Intracellular calcium ([Ca2+]i) signaling is a critical regulator of chondrogenesis, chondrocyte differentiation, and cartilage development. Calcium (Ca2+) signaling is known to direct processes that govern chondrocyte gene expression, protein synthesis, cytoskeletal remodeling, and cell fate. Control of chondrocyte/chondroprogenitor Ca2+ signaling has been attempted through mechanical and/or pharmacological activation of endogenous Ca2+ signaling transducers; however, such approaches can lack specificity and/or precision regarding Ca2+ activation mechanisms. Synthetic signaling platforms permitting precise and selective Ca2+ signal transduction can improve dissection of the roles that [Ca2+]i signaling play in chondrocyte behavior. One such platform is the chemogenetic hM3Dq DREADD (designer receptor exclusively activated by designer drugs) that activates [Ca2+]i signaling via the Gαq-PLCβ-IP3-ER pathway upon clozapine N-oxide (CNO) administration. We previously demonstrated hM3Dq's ability to precisely and synthetically initiate robust [Ca2+]i transients and oscillatory [Ca2+]i signaling in chondrocyte-like ATDC5 cells. Here, we investigate the effects that long-term CNO stimulatory culture have on hM3Dq [Ca2+]i signaling dynamics, proliferation, and protein deposition in 2D ATDC5 cultures. Long-term culturing under repeated CNO stimulation modified the temporal dynamics of hM3Dq [Ca2+]i signaling, increased cell proliferation, and enhanced matrix production in a CNO dose- and frequency-dependent manner, and triggered the formation of cell condensations that developed aligned, anisotropic neotissue structures rich in cartilaginous proteoglycans and collagens, all in the absence of differentiation inducers. This study demonstrated Gαq-GPCR-mediated [Ca2+]i signaling involvement in chondroprogenitor proliferation and cartilage-like matrix production, and established hM3Dq as a powerful tool for elucidating the role of GPCR-mediated Ca2+ signaling in chondrogenesis and chondrocyte differentiation.
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Affiliation(s)
- Ryan C McDonough
- University of Delaware, 5972, Biomedical Engineering, 161 Colburn Lab, Newark, Delaware, United States, 19716-5600;
| | - Christopher Price
- University of Delaware, 5972, Biomedical Engineering, Newark, Delaware, United States;
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Thibodeau S, Yang W, Sharma S, Lytton J. Calmodulin binds and modulates K +-dependent Na +/Ca 2+-exchanger isoform 4, NCKX4. J Biol Chem 2021; 296:100092. [PMID: 33199372 PMCID: PMC7949085 DOI: 10.1074/jbc.ra120.015037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/25/2020] [Accepted: 11/16/2020] [Indexed: 11/06/2022] Open
Abstract
The family of K+-dependent Na+/Ca2+-exchangers, NCKX, are important mediators of cellular Ca2+ efflux, particularly in neurons associated with sensory transduction. The NCKX family comprises five proteins, NCKX1-5, each being the product of a different SLC24 gene. NCKX4 (SLC24A4) has been found to have a critical role in termination and adaptation of visual and olfactory signals, melanocortin-dependent satiety signaling, and the maturation of dental enamel. To explore mechanisms that might influence the temporal control of NCKX4 activity, a yeast two-hybrid system was used to search for protein interaction partners. We identified calmodulin as a partner for NCKX4 and confirmed the interaction using glutathione-S-transferase fusion pull-down. Calmodulin binding to NCKX4 was demonstrated in extracts from mouse brain and in transfected HEK293 cells. Calmodulin bound in a Ca2+-dependent manner to a motif present in the central cytosolic loop of NCKX4 and was abolished by the double-mutant I328D/F334D. When cotransfected in HEK293 cells, calmodulin bound to NCKX4 under basal conditions and induced a ∼2.5-fold increase in NCKX4 abundance, but did not influence either cellular location or basal activity. When purinergic stimulation of NCKX4 was examined in these cells, coexpression of wild-type calmodulin, but not a Ca2+ binding-deficient calmodulin mutant, suppressed NCKX4 activation in a time-dependent manner. We propose that Ca2+ binding to calmodulin prepositioned on NCKX4 induces a slow conformational rearrangement that interferes with purinergic stimulation of the exchanger, possibly by obscuring T331, a previously identified potential protein kinase C site.
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Affiliation(s)
- Stephanie Thibodeau
- Department of Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Weidong Yang
- Department of Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Sunita Sharma
- Department of Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jonathan Lytton
- Department of Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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10
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Wei J, Yao J, Belke D, Guo W, Zhong X, Sun B, Wang R, Paul Estillore J, Vallmitjana A, Benitez R, Hove-Madsen L, Alvarez-Lacalle E, Echebarria B, Chen SRW. Ca 2+-CaM Dependent Inactivation of RyR2 Underlies Ca 2+ Alternans in Intact Heart. Circ Res 2020; 128:e63-e83. [PMID: 33375811 DOI: 10.1161/circresaha.120.318429] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
RATIONALE Ca2+ alternans plays an essential role in cardiac alternans that can lead to ventricular fibrillation, but the mechanism underlying Ca2+ alternans remains undefined. Increasing evidence suggests that Ca2+ alternans results from alternations in the inactivation of cardiac RyR2 (ryanodine receptor 2). However, what inactivates RyR2 and how RyR2 inactivation leads to Ca2+ alternans are unknown. OBJECTIVE To determine the role of CaM (calmodulin) on Ca2+ alternans in intact working mouse hearts. METHODS AND RESULTS We used an in vivo local gene delivery approach to alter CaM function by directly injecting adenoviruses expressing CaM-wild type, a loss-of-function CaM mutation, CaM (1-4), and a gain-of-function mutation, CaM-M37Q, into the anterior wall of the left ventricle of RyR2 wild type or mutant mouse hearts. We monitored Ca2+ transients in ventricular myocytes near the adenovirus-injection sites in Langendorff-perfused intact working hearts using confocal Ca2+ imaging. We found that CaM-wild type and CaM-M37Q promoted Ca2+ alternans and prolonged Ca2+ transient recovery in intact RyR2 wild type and mutant hearts, whereas CaM (1-4) exerted opposite effects. Altered CaM function also affected the recovery from inactivation of the L-type Ca2+ current but had no significant impact on sarcoplasmic reticulum Ca2+ content. Furthermore, we developed a novel numerical myocyte model of Ca2+ alternans that incorporates Ca2+-CaM-dependent regulation of RyR2 and the L-type Ca2+ channel. Remarkably, the new model recapitulates the impact on Ca2+ alternans of altered CaM and RyR2 functions under 9 different experimental conditions. Our simulations reveal that diastolic cytosolic Ca2+ elevation as a result of rapid pacing triggers Ca2+-CaM dependent inactivation of RyR2. The resultant RyR2 inactivation diminishes sarcoplasmic reticulum Ca2+ release, which, in turn, reduces diastolic cytosolic Ca2+, leading to alternations in diastolic cytosolic Ca2+, RyR2 inactivation, and sarcoplasmic reticulum Ca2+ release (ie, Ca2+ alternans). CONCLUSIONS Our results demonstrate that inactivation of RyR2 by Ca2+-CaM is a major determinant of Ca2+ alternans, making Ca2+-CaM dependent regulation of RyR2 an important therapeutic target for cardiac alternans.
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Affiliation(s)
- Jinhong Wei
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Jinjing Yao
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Darrell Belke
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Wenting Guo
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Xiaowei Zhong
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Bo Sun
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Ruiwu Wang
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - John Paul Estillore
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
| | - Alexander Vallmitjana
- Department of Automatic Control, Universitat Politècnica de Catalunya, Barcelona, Spain (A.V., R.B.)
| | - Raul Benitez
- Department of Automatic Control, Universitat Politècnica de Catalunya, Barcelona, Spain (A.V., R.B.).,Institut de Recerca Sant Joan de Déu (IRSJD), Barcelona, Spain (R.B.)
| | - Leif Hove-Madsen
- Biomedical Research Institute Barcelona IIBB-CSIC, CIBERCV and IIB Sant Pau, Hospital de Sant Pau, Barcelona, Spain (L.H.-M.)
| | - Enrique Alvarez-Lacalle
- Department of Physics, Universitat Politècnica de Catalunya, Barcelona, Spain (E.A.-L., B.E.)
| | - Blas Echebarria
- Department of Physics, Universitat Politècnica de Catalunya, Barcelona, Spain (E.A.-L., B.E.)
| | - S R Wayne Chen
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada (J.W., J.Y., D.B., W.G., X.Z., B.S., R.W., J.P.E., S.R.W.C.)
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11
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Beghi S, Cavaliere F, Buschini A. Gene polymorphisms in calcium-calmodulin pathway: Focus on cardiovascular disease. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 786:108325. [PMID: 33339582 DOI: 10.1016/j.mrrev.2020.108325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 07/22/2020] [Accepted: 07/24/2020] [Indexed: 12/30/2022]
Abstract
Cardiovascular disease is the leading cause of death in industrialized countries and affects an increasing number of people. Several risk factors play an important role in the etiology of this disease, such as an unhealthy lifestyle. It is increasingly clear that genetic factors influencing the molecular basis of excitation-contraction mechanisms in the heart could contribute to modify the individual's risk. Thanks to the progress that has been made in understanding calcium signaling in the heart, it is assumed that calmodulin can play a crucial role in the excitation-contraction coupling. In fact, calmodulin (CaM) binds calcium and consequently regulates calcium channels. Several works show how some polymorphic variants can be considered predisposing factors to complex pathologies. Therefore, we hypothesize that the identification of polymorphic variants of proteins involved in the CaM pathway could be important for understanding how genetic traits can influence predisposition to myocardial infarction. This review considers each pathway of the three different isoforms of calmodulin (CaM1; CaM2; CaM3) and focuses on some common proteins involved in the three pathways, with the aim of analyzing the polymorphisms studied in the literature and understanding if they are associated with cardiovascular disease.
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Affiliation(s)
- Sofia Beghi
- University of Parma, Department of Chemistry, Life Sciences and Environmental Sustainability, Parco Area Delle Scienze 11A, 43124, Parma, Italy
| | - Francesca Cavaliere
- University of Parma, Department of Food and Drug, Parco Area Delle Scienze 17A, 43124, Parma, Italy
| | - Annamaria Buschini
- University of Parma, Department of Chemistry, Life Sciences and Environmental Sustainability, Parco Area Delle Scienze 11A, 43124, Parma, Italy.
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12
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Nader M. The SLMAP/Striatin complex: An emerging regulator of normal and abnormal cardiac excitation-contraction coupling. Eur J Pharmacol 2019; 858:172491. [PMID: 31233748 DOI: 10.1016/j.ejphar.2019.172491] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 12/01/2022]
Abstract
The excitation-contraction (E-C) module involves a harmonized correspondence between the sarcolemma and the sarcoplasmic reticulum. This is provided by membrane proteins, which primarily shape the caveolae, the T-tubule/Sarcoplasmic reticulum (TT/SR) junction, and the intercalated discs (ICDs). Distortion of either one of these structures impairs myocardial contraction, and subsequently translates into cardiac failure. Thus, detailed studies on the molecular cues of the E-C module are becoming increasingly necessary to pharmacologically eradicate cardiac failure Herein we reviewed the organization of caveolae, TT/SR junctions, and the ICDs in the heart, with special attention to the Sarcolemma Membrane Associated Protein (SLMAP) and striatin (STRN) in cardiac membranes biology and cardiomyocyte contraction. We emphasized on their in vivo and in vitro signaling in cardiac function/dysfunction. SLMAP is a cardiac membrane protein that plays an important role in E-C coupling and the adrenergic response of the heart. Similarly, STRN is a dynamic protein that is also involved in cardiac E-C coupling and ICD-related cardiomyopathies. Both SLMAP and STRN are linked to cardiac conditions, including heart failure, and their role in cardiomyocyte function was elucidated in our laboratory. They interact together in a protein complex that holds therapeutic potentials for cardiac dysfunction. This review is the first of its kind to conceptualize the role of the SLMAP/STRN complex in cardiac function and failure. It provides in depth information on the signaling of these two proteins and projects their interaction as a novel therapeutic target for cardiac failure.
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Affiliation(s)
- Moni Nader
- Department of Physiological Sciences, College of Medicine, Alfaisal University, Riyadh, 11533, P.O. Box 50927, Saudi Arabia; Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
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13
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Abstract
The transmural heterogeneity of the contractility in ventricular muscle has not been well-studied. Here, we investigated the calcium transient and sarcomere contraction/relaxation in the endocardial (Endo) and epicardial (Epi) myocytes. Endo and Epi myocytes were isolated from C57/BL6 mice by Langendorff perfusion. Ca2+ transient and sarcomere contraction/relaxation were recorded simultaneously at different stimulation frequencies using a dual excitation fluorescence photomultiplier system. We found that the Endo myocytes have higher baseline diastolic calcium, significantly larger calcium transient and stronger sarcomere shortening than Epi myocytes. However, both the rising and decline phases for calcium transient and sarcomere shortening were slower in Endo than in Epi myocytes. When simulation frequency was increased from 1 to 3 Hz, a greater percent increase in the diastole calcium level, Ca2+ transient and sarcomere shortening amplitude has been observed in the Endo myocytes. Accordingly, the frequency-dependent acceleration in the decay rate of calcium transient and sarcomere relaxation was more profound in the Endo than in Epi myocytes. Western blot analysis showed that CaMKII activity was significantly higher in Epi than in Endo myocardium before stimulation. However, this transmural heterogeneity was reversed by rapid pacing. CaMKII inhibition by KN93 diminished the frequency-dependent alterations of Ca2+ transient and sarcomere contraction. Our results suggest that the contractility of ventricular myocytes is heterogeneous. The Endo-myocardium is the major force generating layer in the heart, both at slow and fast heart rate, and the transmural heterogeneity of CaMKII activation plays an important role in the frequency-dependent alterations.
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Affiliation(s)
- Wen Pan
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Ziqi Yang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Cheng Qian
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Medical Research Institute of Wuhan University, Wuhan University, Wuhan, China
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14
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Ding Y, Ling J, Qiao Y, Li Z, Sun Z, Cai J, Guo Y, Wang H. A high-throughput fluorimetric microarray with enhanced fluorescence and suppressed "coffee-ring" effects for the detection of calcium ions in blood. Sci Rep 2016; 6:38602. [PMID: 27917959 PMCID: PMC5137002 DOI: 10.1038/srep38602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/09/2016] [Indexed: 01/29/2023] Open
Abstract
A rapid, ultrasensitive, and high-throughput fluorimetric microarray method has been developed using hydrophobic pattern as the microarray substrate and 3-aminopropyltriethoxysilane-coupled carboxylic acid calcium (APS-CCA) as the fluorescent probes for sensing Ca2+ ions in blood. The hydrophobic pattern of the developed Ca2+ analysis microarray could largely suppress the "coffee-ring" effects to facilitate the better distribution density of testing microspots toward the high-throughput detections, and especially prevent the cross-contamination of the multiple samples between adjacent microspots. Moreover, the use of APS matrix could endow the CCA probe the enhanced environmental stability and fluorescence intensity, which is about 2.3-fold higher than that of free CCA. The interactions between APS-CCA and Ca2+ ions were systematically characterized by UV-vis and fluorescence measurements including microscopy imaging. It was demonstrated that the fluorimetric microarray could display the strong capacity of specifically sensing Ca2+ ions with the minimal interferences from blood backgrounds. Such an APS-CCA-based fluorimetric microarray can allow for the analysis of Ca2+ ions down to 0.0050 mM in blood, promising a highly sensitive and selective detection candidate for Ca2+ ions to be applied in the clinical laboratory.
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Affiliation(s)
- Yanjun Ding
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Jiang Ling
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Yuchun Qiao
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zhengjian Li
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zongzhao Sun
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Jifeng Cai
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Yadong Guo
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Hua Wang
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
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15
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Abstract
Physical challenges, emotional arousal, increased physical activity, or changes in the environment can evoke stress, requiring altered activity of visceral organs, glands, and smooth muscles. These alterations are necessary for the organism to function appropriately under these abnormal conditions and to restore homeostasis. These changes in activity comprise the "fight-or-flight" response and must occur rapidly or the organism may not survive. The rapid responses are mediated primarily via the catecholamines, epinephrine, and norepinephrine, secreted from the adrenal medulla. The catecholamine neurohormones interact with adrenergic receptors present on cell membranes of all visceral organs and smooth muscles, leading to activation of signaling pathways and consequent alterations in organ function and smooth muscle tone. During the "fight-or-flight response," the rise in circulating epinephrine and norepinephrine from the adrenal medulla and norepinephrine secreted from sympathetic nerve terminals cause increased blood pressure and cardiac output, relaxation of bronchial, intestinal and many other smooth muscles, mydriasis, and metabolic changes that increase levels of blood glucose and free fatty acids. Circulating catecholamines can also alter memory via effects on afferent sensory nerves impacting central nervous system function. While these rapid responses may be necessary for survival, sustained elevation of circulating catecholamines for prolonged periods of time can also produce pathological conditions, such as cardiac hypertrophy and heart failure, hypertension, and posttraumatic stress disorder. In this review, we discuss the present knowledge of the effects of circulating catecholamines on peripheral organs and tissues, as well as on memory in the brain.
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Affiliation(s)
- A William Tank
- Department of Pharmacology & Physiology, University of Rochester Medical Center, Rochester, NY, USA
| | - Dona Lee Wong
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, MA, USA
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16
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Echinochrome A regulates phosphorylation of phospholamban Ser16 and Thr17 suppressing cardiac SERCA2A Ca²⁺ reuptake. Pflugers Arch 2014; 467:2151-63. [PMID: 25410495 DOI: 10.1007/s00424-014-1648-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/24/2014] [Accepted: 11/04/2014] [Indexed: 02/05/2023]
Abstract
Echinochrome A (Ech A), a marine bio-product isolated from sea urchin eggs, is known to have cardioprotective effects through its strong antioxidant and ATP-sparing capabilities. However, the effects of Ech A on cardiac excitation-contraction (E-C) are not known. In this study, we investigated the effects of Ech A on cardiac contractility and Ca(2+) handling in the rat heart. In ex vivo Langendorff hearts, Ech A (3 μM) decreased left ventricular developing pressure to 77.7 ± 6.5 % of basal level. In isolated ventricular myocytes, Ech A reduced the fractional cell shortening from 3.4 % at baseline to 2.1 %. Ech A increased both diastolic and peak systolic intracellular Ca(2+) ([Ca(2+)]i). However, the ratio of peak [Ca]i to resting [Ca]i was significantly decreased. Ech A did not affect the L-type Ca(2+) current. Inhibiting the Na(+)/Ca(2+) exchanger with either NiCl2 or SEA400 did not affect the Ech A-dependent changes in Ca(2+) handling. Our data demonstrate that treatment with Ech A results in a significant reduction in the phosphorylation of phospholamban at both serine 16 and threonine 17 leading to a significant inhibition of SR Ca(2+)-ATPase 2A (SERCA2A) and subsequent reduced Ca(2+) uptake into the intracellular Ca(2+) store. Taken together, our data show that Ech A negatively regulates cardiac contractility by inhibiting SERCA2A activity, which leads to a reduction in internal Ca(2+) stores.
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17
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Calmodulin modulates the termination threshold for cardiac ryanodine receptor-mediated Ca2+ release. Biochem J 2014; 455:367-75. [PMID: 23992453 DOI: 10.1042/bj20130805] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
RyR2 (cardiac ryanodine receptor)-mediated Ca2+ release in cardiomyocytes terminates when the sarcoplasmic reticulum Ca2+ content depletes to a threshold level, known as the termination threshold. Despite its importance, little is known about the mechanism that regulates the termination threshold. CaM (calmodulin), by inhibiting RyR2, has been implicated in Ca2+-release termination, but whether CaM modulates the termination threshold is unknown. To this end, we monitored the endoplasmic reticulum Ca2+ dynamics in RyR2-expressing HEK (human embryonic kidney)-293 cells transfected with WT (wild-type) CaM or mutants. We found that WT CaM or CaM mutations which abolish Ca2+ binding to the N-lobe (N-terminal lobe) of CaM increased the termination threshold (i.e. facilitated termination), but had no effect on the activation threshold at which spontaneous Ca2+ release occurs. On the other hand, CaM mutations that diminish Ca2+ binding to both the N-lobe and C-lobe (C-terminal lobe), or the C-lobe only, decreased the termination threshold (i.e. delayed termination) with a similar activation threshold. Furthermore, deletion of residues 3583-3603 or point mutations (W3587A/L3591D/F3603A, W3587A, or L3591D) in the CaM-binding domain of RyR2 that are known to abolish or retain CaM binding all reduced the termination threshold without having a significant impact on the activation threshold. Interestingly, the RyR2-F3603A mutation affected both the activation and termination threshold. Collectively, these data indicate that CaM facilitates the termination of Ca2+ release by increasing the termination threshold, and that this action of CaM depends on Ca2+ binding to the C-lobe, but not to the N-lobe, of CaM. The results of the present study also suggest that the CaM-binding domain of RyR2 is an important determinant of Ca2+-release termination and activation.
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18
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Yang PC, Clancy CE. Gender-based differences in cardiac diseases. J Biomed Res 2013; 25:81-9. [PMID: 23554675 PMCID: PMC3596698 DOI: 10.1016/s1674-8301(11)60010-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 11/18/2010] [Accepted: 01/11/2011] [Indexed: 12/11/2022] Open
Abstract
It has been observed that the incidence of heart failure and Brugada syndrome are higher in men, while women are more likely to have QT interval prolongation and develop torsades de pointes (TdP). Over the past decade, new studies have improved our understanding of the mechanisms of abnormal repolarization and the relationship between gender differences in cardiac repolarization and presentation of clinical syndromes. Nevertheless, the causes of gender-based differences in cardiac disease are still not completely clear. This review paper briefly summarized what is currently known about gender differences in heart failure, Brugada syndrome and long QT syndrome from molecular mechanisms to clinical presentations.
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Affiliation(s)
- Pei-Chi Yang
- Department of Pharmacology, University of California Davis. Davis, CA 96516-5270, USA
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19
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Yang D, Lyashkov AE, Li Y, Ziman BD, Lakatta EG. RGS2 overexpression or G(i) inhibition rescues the impaired PKA signaling and slow AP firing of cultured adult rabbit pacemaker cells. J Mol Cell Cardiol 2012; 53:687-94. [PMID: 22921807 DOI: 10.1016/j.yjmcc.2012.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 07/23/2012] [Accepted: 08/10/2012] [Indexed: 12/16/2022]
Abstract
Freshly isolated adult rabbit sinoatrial node cells (f-SANC) are an excellent model for studies of autonomic signaling, but are not amenable to genetic manipulation. We have developed and characterized a stable cultured rabbit SANC (c-SANC) model that is suitable for genetic manipulation to probe mechanisms of spontaneous action potential (AP) firing. After 48 h in culture, c-SANC generate stable, rhythmic APs at 34±0.5°C, at a rate that is 50% less than f-SANC. In c- vs. f-SANC: AP duration is prolonged; phosphorylation of phospholamban at Ser(16) and type2 ryanodine receptor (RyR2) at Ser(2809) are reduced; and the level of type2 regulator of G-protein signaling (RGS2), that facilitates adenylyl cyclases/cAMP/protein kinase A (PKA) via G(i) inhibition, is substantially reduced. Consistent with the interpretation that cAMP/PKA signaling becomes impaired in c-SANC, acute β-adrenergic receptor stimulation increases phospholamban and RyR2 phosphorylation, enhances RGS2-labeling density, and accelerates the AP firing rate to the similar maximum in c- and f-SANC. Specific PKA inhibition completely inhibits all β-adrenergic receptor effects. Adv-RGS2 infection, or pertussis toxin treatment to disable G(i)-signaling, each partially rescues the c-SANC spontaneous AP firing rate. Thus, a G(i)-dependent reduction in PKA-dependent protein phosphorylation, including that of Ca(2+) cycling proteins, reduces the spontaneous AP firing rate of c-SANC, and can be reversed by genetic or pharmacologic manipulation of PKA signaling.
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Affiliation(s)
- Dongmei Yang
- Laboratory of Cardiovascular Science, IRP, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224-6825, USA
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20
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Cyclic AMP-dependent protein kinase A regulates the alternative splicing of CaMKIIδ. PLoS One 2011; 6:e25745. [PMID: 22132070 PMCID: PMC3222655 DOI: 10.1371/journal.pone.0025745] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2011] [Accepted: 09/09/2011] [Indexed: 01/08/2023] Open
Abstract
Ca(2+)/calmodulin-dependent protein kinase (CaMK) IIδ is predominantly expressed in the heart. There are three isoforms of CaMKIIδ resulting from the alternative splicing of exons 14, 15, and 16 of its pre-mRNA, which is regulated by the splicing factor SF2/ASF. Inclusion of exons 15 and 16 or of exon 14 generates δA or δB isoform. The exclusion of all three exons gives rise to δC isoform, which is selectively increased in pressure-overload-induced hypertrophy. Overexpression of either δB or δC induces hypertrophy and heart failure, suggesting their specific role in the pathogenesis of hypertrophy and heart failure. It is well known that the β-adrenergic-cyclic AMP-dependent protein kinase A (PKA) pathway is implicated in heart failure. To determine the role of PKA in the alternative splicing of CaMKIIδ, we constructed mini-CaMKIIδ genes and used these genes to investigate the regulation of the alternative splicing of CaMKIIδ by PKA in cultured cells. We found that PKA promoted the exclusion of exons 14, 15, and 16 of CaMKIIδ, resulting in an increase in δC isoform. PKA interacted with and phosphorylated SF2/ASF, and enhanced SF2/ASF's activity to promote the exclusion of exons 14, 15, and 16 of CaMKIIδ, leading to a further increase in the expression of δC isoform. These findings suggest that abnormality in β-adrenergic-PKA signaling may contribute to cardiomyopathy and heart failure through dysregulation in the alternative splicing of CaMKIIδ exons 14, 15, and 16 and up-regulation of CaMKIIδC.
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21
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Ca2+ disorder caused by rapid electrical field stimulation can be modulated by CaMKIIδ expression in primary rat atrial myocytes. Biochem Biophys Res Commun 2011; 409:287-92. [DOI: 10.1016/j.bbrc.2011.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 05/02/2011] [Indexed: 11/19/2022]
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22
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Gender-related differences in ion-channel and transporter subunit expression in non-diseased human hearts. J Mol Cell Cardiol 2010; 49:639-46. [PMID: 20600101 DOI: 10.1016/j.yjmcc.2010.06.005] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/27/2010] [Accepted: 06/15/2010] [Indexed: 01/14/2023]
Abstract
Gender-related differences in ventricular electrophysiology are known to be important determinants of human arrhythmic risk, but the underlying molecular basis is poorly understood. The present work aims to provide the first detailed analysis of gender-related cardiac ion-channel gene-distribution, based on samples from non-diseased human hearts. By using a high-throughput quantitative approach, we investigated at a genome-scale the expression of 79 genes encoding ion-channel and transporter subunits in epicardial and endocardial tissue samples from non-diseased transplant donors (10 males, 10 females). Gender-related expression differences involved key genes implicated in conduction and repolarization. Female hearts showed reduced expression for a variety of K(+)-channel subunits with potentially important roles in cardiac repolarization, including HERG, minK, Kir2.3, Kv1.4, KChIP2, SUR2 and Kir6.2, as well as lower expression of connexin43 and phospholamban. In addition, they demonstrated an isoform switch in Na(+)/K(+)-ATPase, expressing more of the alpha1 and less of the alpha3 subunit than male hearts, along with increased expression of calmodulin-3. Iroquois transcription factors (IRX3, IRX5) were more strongly expressed in female than male epicardium, but the transmural gradient remained. Protein-expression paralleled transcript patterns for all subunits examined: HERG, minK, Kv1.4, KChIP2, IRX5, Nav1.5 and connexin43. Our results indicate that male and female human hearts have significant differences in ion-channel subunit composition, with female hearts showing decreased expression for a number of repolarizing ion-channels. These findings are important for understanding sex-related differences in the susceptibility to ventricular arrhythmias, particularly for conditions associated with repolarization abnormalities like Brugada and Long QT syndrome.
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23
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Han DY, Minobe E, Wang WY, Guo F, Xu JJ, Hao LY, Kameyama M. Calmodulin- and Ca2+-dependent facilitation and inactivation of the Cav1.2 Ca2+ channels in guinea-pig ventricular myocytes. J Pharmacol Sci 2010; 112:310-9. [PMID: 20197640 DOI: 10.1254/jphs.09282fp] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The L-type Ca(2+) channel (Ca(V)1.2) shows clear Ca(2+)-dependent facilitation and inactivation. Here we have examined the effects of calmodulin (CaM) and Ca(2+) on Ca(2+) channel in guinea-pig ventricular myocytes in the inside-out patch mode, where rundown of the channels was controlled. At a free [Ca(2+)] of 0.1 microM, CaM (0.15, 0.7, 1.4, 2.1, 3.5, and 7.0 microM) + ATP (2.4 mM) induced channel activities of 27%, 98%, 142%, 222%, 65%, and 20% relative to the control activity, respectively, showing a bell-shaped relationship. Similar results were observed at a free [Ca(2+)] <0.01 microM or with a Ca(2+)-insensitive mutant, CaM(1234), suggesting that apoCaM may induce facilitation and inactivation of the channel activity. The bell-shaped curve of CaM was shifted to the lower concentration side with increasing [Ca(2+)]. A simple model for CaM- and Ca(2+)-dependent modulations of the channel activity, which involves two CaM-binding sites, was proposed. We suggest that both apoCaM and Ca(2+)/CaM can induce facilitation and inactivation of Ca(V)1.2 Ca(2+) channels and that the basic role of Ca(2+) is to accelerate CaM-dependent facilitation and inactivation.
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Affiliation(s)
- Dong-Yun Han
- School of Pharmaceutical Science, China Medical University, Shenyang, China
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24
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Yang D, Zhu WZ, Xiao B, Brochet DXP, Chen SRW, Lakatta EG, Xiao RP, Cheng H. Ca
2+
/Calmodulin Kinase II-Dependent Phosphorylation of Ryanodine Receptors Suppresses Ca
2+
Sparks and Ca
2+
Waves in Cardiac Myocytes. Circ Res 2007; 100:399-407. [PMID: 17234969 DOI: 10.1161/01.res.0000258022.13090.55] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The multifunctional Ca
2+
/calmodulin-dependent protein kinase II δ
C
(CaMKIIδ
C
) is found in the macromolecular complex of type 2 ryanodine receptor (RyR2) Ca
2+
release channels in the heart. However, the functional role of CaMKII-dependent phosphorylation of RyR2 is highly controversial. To address this issue, we expressed wild-type, constitutively active, or dominant-negative CaMKIIδ
C
via adenoviral gene transfer in cultured adult rat ventricular myocytes. CaMKII-mediated phosphorylation of RyR2 was reduced, enhanced, or unaltered by dominant-negative, constitutively active, or wild-type CaMKIIδ
C
expression, whereas phosphorylation of phospholamban at Thr17, an endogenous indicator of CaMKII activity, was at 73%, 161%, or 115% of the control group expressing β-galactosidase (β-gal), respectively. In parallel with the phospholamban phosphorylation, the decay kinetics of global Ca
2+
transients was slowed, accelerated, or unchanged, whereas spontaneous Ca
2+
spark activity was hyperactive, depressed, or unchanged in dominant-negative, constitutively active, or wild-type CaMKIIδ
C
groups, respectively. When challenged by high extracellular Ca
2+
, both wild-type and constitutively active CaMKIIδ
C
protected the cells from store overload-induced Ca
2+
release, manifested by a ≈60% suppression of Ca
2+
waves (at 2 to 20 mmol/L extracellular Ca
2+
) in spite of an elevated sarcoplasmic reticulum Ca
2+
content, whereas dominant-negative CaMKIIδ
C
promoted Ca
2+
wave production (at 20 mmol/L Ca
2+
) with significantly depleted sarcoplasmic reticulum Ca
2+
. Taken together, our data support the notion that CaMKIIδ
C
negatively regulates RyR2 activity and spontaneous sarcoplasmic reticulum Ca
2+
release, thereby affording a negative feedback that stabilizes local and global Ca
2+
-induced Ca
2+
release in the heart.
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Affiliation(s)
- Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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25
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Wang Y, Cheng J, Tandan S, Jiang M, McCloskey DT, Hill JA. Transient-outward K+ channel inhibition facilitates L-type Ca2+ current in heart. J Cardiovasc Electrophysiol 2006; 17:298-304. [PMID: 16643405 DOI: 10.1111/j.1540-8167.2006.00362.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Transient outward current (I(to)) and L-type calcium current (I(Ca)) are important repolarization currents in cardiac myocytes. These two currents often undergo disease-related remodeling while other currents are spared, suggesting a functional coupling between them. Here, we investigated the effects of I(to) channel blockers, 4-aminopyridine (4-AP) and heteropodatoxin-2 (HpTx2), on I(Ca) in cardiac ventricular myocytes. METHODS AND RESULTS I(Ca) was recorded in enzymatically dissociated mouse and guinea pig ventricular myocytes using the whole-cell voltage clamp method. In mouse ventricular myocytes, 4-AP (2 mM) significantly facilitated I(Ca) by increasing current amplitude and slowing inactivation. These effects were not voltage-dependent. Similar facilitating effects were seen when equimolar Ba2+ was substituted for external Ca2+, indicating that Ca2+ influx is not required. Measurements of Ca2+/calmodulin-dependent protein kinase (CaMKII) activity revealed significant increases in cells treated with 4-AP. Pretreatment of cells with 10 microM KN93, a specific inhibitor of CaMKII, abolished the effects of 4-AP on I(Ca.) To test the requirement of I(to), we studied guinea pig ventricular myocytes, which do not express I(to) channels. In these cells, 2 mM 4-AP had no effect on I(Ca) amplitude or kinetics. In both cell types, Ca2+-induced I(Ca) facilitation, a CaMKII-dependent process, was observed. However, 4-AP abolished Ca2+-induced I(Ca) facilitation exclusively in mouse ventricular myocytes. CONCLUSION 4-AP, an I(to) blocker, facilitates L-type Ca2+ current through a mechanism involving the I(to) channel and CaMKII activation. These data indicate a functional association of I(Ca) and I(to) in cardiac myocytes.
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Affiliation(s)
- Yanggan Wang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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26
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Bodi I, Mikala G, Koch SE, Akhter SA, Schwartz A. The L-type calcium channel in the heart: the beat goes on. J Clin Invest 2006; 115:3306-17. [PMID: 16322774 PMCID: PMC1297268 DOI: 10.1172/jci27167] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sydney Ringer would be overwhelmed today by the implications of his simple experiment performed over 120 years ago showing that the heart would not beat in the absence of Ca2+. Fascination with the role of Ca2+ has proliferated into all aspects of our understanding of normal cardiac function and the progression of heart disease, including induction of cardiac hypertrophy, heart failure, and sudden death. This review examines the role of Ca2+ and the L-type voltage-dependent Ca2+ channels in cardiac disease.
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Affiliation(s)
- Ilona Bodi
- Institute of Molecular Pharmacology and Biophysics, University of Cincinnati College of Medicine, Ohio 45267, USA
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27
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Goonasekera SA, Chen SRW, Dirksen RT. Reconstitution of local Ca2+ signaling between cardiac L-type Ca2+ channels and ryanodine receptors: insights into regulation by FKBP12.6. Am J Physiol Cell Physiol 2005; 289:C1476-84. [PMID: 16049053 DOI: 10.1152/ajpcell.00250.2005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca+-induced Ca2+ release (CICR) in the heart involves local Ca2+ signaling between sarcolemmal L-type Ca2+ channels (dihydropyridine receptors, DHPRs) and type 2 ryanodine receptors (RyR2s) in the sarcoplasmic reticulum (SR). We reconstituted cardiac-like CICR by expressing a cardiac dihydropyridine-insensitive (T1066Y/Q1070M) α1-subunit (α1CYM) and RyR2 in myotubes derived from RyR1-knockout (dyspedic) mice. Myotubes expressing α1CYM and RyR2 were vesiculated and exhibited spontaneous Ca2+ oscillations that resulted in chaotic and uncontrolled contractions. Coexpression of FKBP12.6 (but not FKBP12.0) with α1CYM and RyR2 eliminated vesiculations and reduced the percentage of myotubes exhibiting uncontrolled global Ca2+ oscillations (63% and 13% of cells exhibited oscillations in the absence and presence of FKBP12.6, respectively). α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited robust and rapid electrically evoked Ca2+ transients that required extracellular Ca2+. Depolarization-induced Ca2+ release in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a bell-shaped voltage dependence that was fourfold larger than that of myotubes expressing α1CYM alone (maximal fluorescence change was 2.10 ± 0.39 and 0.54 ± 0.07, respectively), despite similar Ca2+ current densities. In addition, the gain of CICR in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a nonlinear voltage dependence, being considerably larger at threshold potentials. We used this molecular model of local α1C-RyR2 signaling to assess the ability of FKBP12.6 to inhibit spontaneous Ca2+ release via a phosphomimetic mutation in RyR2 (S2808D). Electrically evoked Ca2+ release and the incidence of spontaneous Ca2+ oscillations did not differ in wild-type RyR2- and S2808D-expressing myotubes over a wide range of FKBP12.6 expression. Thus a negative charge at S2808 does not alter in situ regulation of RyR2 by FKBP12.6.
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Affiliation(s)
- Sanjeewa A Goonasekera
- Dept. of Pharmacology and Physiology, Univ. of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14642, USA
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28
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Brette F, Leroy J, Le Guennec JY, Sallé L. Ca2+ currents in cardiac myocytes: Old story, new insights. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 91:1-82. [PMID: 16503439 DOI: 10.1016/j.pbiomolbio.2005.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Calcium is a ubiquitous second messenger which plays key roles in numerous physiological functions. In cardiac myocytes, Ca2+ crosses the plasma membrane via specialized voltage-gated Ca2+ channels which have two main functions: (i) carrying depolarizing current by allowing positively charged Ca2+ ions to move into the cell; (ii) triggering Ca2+ release from the sarcoplasmic reticulum. Recently, it has been suggested than Ca2+ channels also participate in excitation-transcription coupling. The purpose of this review is to discuss the physiological roles of Ca2+ currents in cardiac myocytes. Next, we describe local regulation of Ca2+ channels by cyclic nucleotides. We also provide an overview of recent studies investigating the structure-function relationship of Ca2+ channels in cardiac myocytes using heterologous system expression and transgenic mice, with descriptions of the recently discovered Ca2+ channels alpha(1D) and alpha(1E). We finally discuss the potential involvement of Ca2+ currents in cardiac pathologies, such as diseases with autoimmune components, and cardiac remodeling.
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Affiliation(s)
- Fabien Brette
- School of Biomedical Sciences, University of Leeds, Worsley Building Leeds, LS2 9NQ, UK.
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29
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Xiong L, Kleerekoper QK, He R, Putkey JA, Hamilton SL. Sites on Calmodulin That Interact with the C-terminal Tail of Cav1.2 Channel. J Biol Chem 2005; 280:7070-9. [PMID: 15583004 DOI: 10.1074/jbc.m410558200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two fragments of the C-terminal tail of the alpha(1) subunit (CT1, amino acids 1538-1692 and CT2, amino acids 1596-1692) of human cardiac L-type calcium channel (Ca(V)1.2) have been expressed, refolded, and purified. A single Ca(2+)-calmodulin binds to each fragment, and this interaction with Ca(2+)-calmodulin is required for proper folding of the fragment. Ca(2+)-calmodulin, bound to these fragments, is in a more extended conformation than calmodulin bound to a synthetic peptide representing the IQ motif, suggesting that either the conformation of the IQ sequence is different in the context of the longer fragment, or other sequences within CT2 contribute to the binding of calmodulin. NMR amide chemical shift perturbation mapping shows the backbone conformation of calmodulin is nearly identical when bound to CT1 and CT2, suggesting that amino acids 1538-1595 do not contribute to or alter calmodulin binding to amino acids 1596-1692 of Ca(V)1.2. The interaction with CT2 produces the greatest changes in the backbone amides of hydrophobic residues in the N-lobe and hydrophilic residues in the C-lobe of calmodulin and has a greater effect on residues located in Ca(2+) binding loops I and II in the N-lobe relative to loops III and IV in the C-lobe. In conclusion, Ca(2+)-calmodulin assumes a novel conformation when part of a complex with the C-terminal tail of the Ca(V)1.2 alpha(1) subunit that is not duplicated by synthetic peptides corresponding to the putative binding motifs.
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Affiliation(s)
- Liangwen Xiong
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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30
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Wang MC, Dolphin A, Kitmitto A. L-type voltage-gated calcium channels: understanding function through structure. FEBS Lett 2004; 564:245-50. [PMID: 15111104 DOI: 10.1016/s0014-5793(04)00253-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Accepted: 02/23/2004] [Indexed: 11/19/2022]
Abstract
L-type voltage-gated calcium channels (VGCCs) are multisubunit membrane proteins that regulate calcium influx into excitable cells. Within the last two years there have been four separate reports describing the structure of the skeletal muscle VGCC determined by electron microscopy and single particle analysis methods. There are some discrepancies between the structures, as well as reports for both monomeric and dimeric forms of the channel. This article considers each of the VGCC structures in terms of similarities and differences with an emphasis upon translation of data into a biological context.
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Affiliation(s)
- Ming-Chuan Wang
- Department of Biomolecular Sciences, University of Manchester Institute of Science and Technology, Manchester M60 1QD, UK
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31
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Wehrens XHT, Lehnart SE, Reiken SR, Marks AR. Ca2+/calmodulin-dependent protein kinase II phosphorylation regulates the cardiac ryanodine receptor. Circ Res 2004; 94:e61-70. [PMID: 15016728 DOI: 10.1161/01.res.0000125626.33738.e2] [Citation(s) in RCA: 467] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The cardiac ryanodine receptor (RyR2)/calcium release channel on the sarcoplasmic reticulum is required for muscle excitation-contraction coupling. Using site-directed mutagenesis, we identified the specific Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation site on recombinant RyR2, distinct from the site for protein kinase A (PKA) that mediates the "fight-or-flight" stress response. CaMKII phosphorylation increased RyR2 Ca2+ sensitivity and open probability. CaMKII was activated at increased heart rates, which may contribute to enhanced Ca2+-induced Ca2+ release. Moreover, rate-dependent CaMKII phosphorylation of RyR2 was defective in heart failure. CaMKII-mediated phosphorylation of RyR2 may contribute to the enhanced contractility observed at higher heart rates. The full text of this article is available online at http://circres.ahajournals.org.
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Affiliation(s)
- Xander H T Wehrens
- Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, 630 W 168th St, P&S 9-401, Box 65, New York, NY 10032, USA
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