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Boda VK, Yasmen N, Jiang J, Li W. Pathophysiological significance and modulation of the transient receptor potential canonical 3 ion channel. Med Res Rev 2024. [PMID: 38715347 DOI: 10.1002/med.22048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/11/2024] [Accepted: 04/23/2024] [Indexed: 05/12/2024]
Abstract
Transient receptor potential canonical 3 (TRPC3) protein belongs to the TRP family of nonselective cation channels. Its activation occurs by signaling through a G protein-coupled receptor (GPCR) and a phospholipase C-dependent (PLC) pathway. Perturbations in the expression of TRPC3 are associated with a plethora of pathophysiological conditions responsible for disorders of the cardiovascular, immune, and central nervous systems. The recently solved cryo-EM structure of TRPC3 provides detailed inputs about the underlying mechanistic aspects of the channel, which in turn enables more efficient ways of designing small-molecule modulators. Pharmacologically targeting TRPC3 in animal models has demonstrated great efficacy in treating diseases including cancers, neurological disorders, and cardiovascular diseases. Despite extensive scientific evidence supporting some strong correlations between the expression and activity of TRPC3 and various pathophysiological conditions, therapeutic strategies based on its pharmacological modulations have not led to clinical trials. The development of small-molecule TRPC3 modulators with high safety, sufficient brain penetration, and acceptable drug-like profiles remains in progress. Determining the pathological mechanisms for TRPC3 involvement in human diseases and understanding the requirements for a drug-like TRPC3 modulator will be valuable in advancing small-molecule therapeutics to future clinical trials. In this review, we provide an overview of the origin and activation mechanism of TRPC3 channels, diseases associated with irregularities in their expression, and new development in small-molecule modulators as potential therapeutic interventions for treating TRPC3 channelopathies.
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Affiliation(s)
- Vijay K Boda
- Department of Pharmaceutical Sciences, and Drug Discovery Center, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Nelufar Yasmen
- Department of Pharmaceutical Sciences, and Drug Discovery Center, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Jianxiong Jiang
- Department of Pharmaceutical Sciences, and Drug Discovery Center, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Wei Li
- Department of Pharmaceutical Sciences, and Drug Discovery Center, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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2
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Fazio A, Evangelisti C, Cappellini A, Mongiorgi S, Koufi FD, Neri I, Marvi MV, Russo M, Ghigo A, Manzoli L, Fiume R, Ratti S. Emerging Roles of Phospholipase C Beta Isozymes as Potential Biomarkers in Cardiac Disorders. Int J Mol Sci 2023; 24:13096. [PMID: 37685903 PMCID: PMC10487445 DOI: 10.3390/ijms241713096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/19/2023] [Accepted: 08/21/2023] [Indexed: 09/10/2023] Open
Abstract
Phospholipase C (PLC) enzymes represent crucial participants in the plasma membrane of mammalian cells, including the cardiac sarcolemmal (SL) membrane of cardiomyocytes. They are responsible for the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) into 1,2-diacylglycerol (DAG) and inositol (1,4,5) trisphosphate (Ins(1,4,5)P3), both essential lipid mediators. These second messengers regulate the intracellular calcium (Ca2+) concentration, which activates signal transduction cascades involved in the regulation of cardiomyocyte activity. Of note, emerging evidence suggests that changes in cardiomyocytes' phospholipid profiles are associated with an increased occurrence of cardiovascular diseases, but the underlying mechanisms are still poorly understood. This review aims to provide a comprehensive overview of the significant impact of PLC on the cardiovascular system, encompassing both physiological and pathological conditions. Specifically, it focuses on the relevance of PLCβ isoforms as potential cardiac biomarkers, due to their implications for pathological disorders, such as cardiac hypertrophy, diabetic cardiomyopathy, and myocardial ischemia/reperfusion injury. Gaining a deeper understanding of the mechanisms underlying PLCβ activation and regulation is crucial for unraveling the complex signaling networks involved in healthy and diseased myocardium. Ultimately, this knowledge holds significant promise for advancing the development of potential therapeutic strategies that can effectively target and address cardiac disorders by focusing on the PLCβ subfamily.
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Affiliation(s)
- Antonietta Fazio
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Camilla Evangelisti
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Alessandra Cappellini
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Sara Mongiorgi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Foteini-Dionysia Koufi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Irene Neri
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Maria Vittoria Marvi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Michele Russo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center “Guido Tarone”, University of Torino, 10126 Torino, Italy; (M.R.); (A.G.)
| | - Alessandra Ghigo
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center “Guido Tarone”, University of Torino, 10126 Torino, Italy; (M.R.); (A.G.)
| | - Lucia Manzoli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Roberta Fiume
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
| | - Stefano Ratti
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy; (A.F.); (C.E.); (A.C.); (S.M.); (F.-D.K.); (I.N.); (M.V.M.); (L.M.)
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3
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Lou JQ, Cao Y, Yu YJ, Hu L, Mao ZS, Huang P, Hua X, Chen F. Investigation of heart lipid changes in acute β-AR activation-induced sudden cardiac death by time-of-flight secondary ion mass spectrometry. Analyst 2020; 145:5889-5896. [DOI: 10.1039/d0an00768d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
ToF-SIMS, PCA and PLS-DA were combined to compare lipid profiles of myocardial tissue in sudden cardiac death and normal, mice and humans. SIMS imaging was utilized to correlate the composition and structural changes.
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Affiliation(s)
- Jia-Qian Lou
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
| | - Yue Cao
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
| | - You-Jia Yu
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
| | - Li Hu
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
| | - Zheng-Sheng Mao
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
| | - Ping Huang
- Shanghai Key Laboratory of Forensic Medicine
- Shanghai Forensic Service Platform
- Academy of Forensic Science
- Shanghai
- China
| | - Xin Hua
- Department of Chemistry
- East China University of Science and Technology
- Shanghai
- China
| | - Feng Chen
- Department of Forensic Medicine
- Nanjing Medical University
- Nanjing
- China
- Key Laboratory of Targeted Intervention of Cardiovascular Disease
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4
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Mitrokhin V, Filatova T, Shim A, Bilichenko A, Abramochkin D, Kamkin A, Mladenov M. L-type Ca2+ channels’ involvement in IFN-γ-induced signaling in rat ventricular cardiomyocytes. J Physiol Biochem 2019; 75:109-115. [DOI: 10.1007/s13105-019-00662-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 01/22/2019] [Indexed: 12/31/2022]
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5
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Wang DL, Dai WY, Wang W, Wen Y, Zhou Y, Zhao YT, Wu J, Liu P. Interfering RNA against PKC-α inhibits TNF-α-induced IP 3R1 expression and improves glomerular filtration rate in rats with fulminant hepatic failure. Am J Physiol Renal Physiol 2018; 314:F942-F955. [PMID: 29357415 DOI: 10.1152/ajprenal.00433.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We have reported that tumor necrosis factor-α (TNF-α) is critical for reduction of glomerular filtration rate (GFR) in rats with fulminant hepatic failure (FHF). The present study aims to evaluate the underlying mechanisms of decreased GFR during acute hepatic failure. Rats with FHF induced by d-galactosamine plus lipopolysaccharide (GalN/LPS) were injected intravenously with recombinant lentivirus harboring short hairpin RNA against the protein kinase C-α ( PKC-α) gene (Lenti-shRNA-PKC-α). GFR, serum levels of aminotransferases, creatinine, urea nitrogen, potassium, sodium, chloride, TNF-α, and endothelin-1 (ET-1), as well as type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) expression in renal tissue were assessed. The effects of PKC-α silencing on TNF-α-induced IP3R1, specificity protein 1 (SP-1), and c-Jun NH2-terminal kinase (JNK) expression, as well as cytosolic calcium content were determined in glomerular mesangial cell (GMCs) with RNAi against PKC-α. Renal IP3R1 overexpression was abrogated by pre-treatment with Lenti-shRNA-PKC-α. The PKC-α silence significantly improved the compromised GFR, reduced Cr levels, and reversed the decrease in glomerular inulin space and the increase in glomerular calcium content in GalN/LPS-exposed rats. TNF-α treatment increased expression of PKC-α, IP3R1, specificity protein 1 (SP-1), JNK, and p-JNK in GMCs and increased Ca2 + release and binding activity of SP-1 to the IP3R1 promoter. These effects were blocked by transfection of siRNA against the PKC-α gene, and the PKC-α gene silence also restored cytosolic Ca2+ concentration. RNAi targeting PKC-α inhibited TNF-α-induced IP3R1 overexpression and in turn improved compromised GFR in the development of acute kidney injury during FHF in rats.
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Affiliation(s)
- Dong-Lei Wang
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, Liaoning Province, People's Republic of China
| | - Wen-Ying Dai
- The Sixth People's Hospital of Shenyang, Shenyang City, Liaoning Province, People's Republic of China
| | - Wen Wang
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, Liaoning Province, People's Republic of China
| | - Ying Wen
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, Liaoning Province, People's Republic of China
| | - Ying Zhou
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, Liaoning Province, People's Republic of China
| | - Yi-Tong Zhao
- The Sixth People's Hospital of Shenyang, Shenyang City, Liaoning Province, People's Republic of China
| | - Jian Wu
- Department of Medical Microbiology, Key Laboratory of Medical Molecular Virology, School of Basic Medical Sciences, Fudan University , Shanghai , China.,Shanghai Institute of Liver Diseases, Fudan University , Shanghai , China
| | - Pei Liu
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, Liaoning Province, People's Republic of China.,The Institute of liver diseases, China Medical University, Shenyang, Liaoning Province, China
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6
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Garcia MI, Karlstaedt A, Chen JJ, Amione-Guerra J, Youker KA, Taegtmeyer H, Boehning D. Functionally redundant control of cardiac hypertrophic signaling by inositol 1,4,5-trisphosphate receptors. J Mol Cell Cardiol 2017; 112:95-103. [PMID: 28923351 DOI: 10.1016/j.yjmcc.2017.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 09/09/2017] [Accepted: 09/14/2017] [Indexed: 01/06/2023]
Abstract
Calcium plays an integral role to many cellular processes including contraction, energy metabolism, gene expression, and cell death. The inositol 1, 4, 5-trisphosphate receptor (IP3R) is a calcium channel expressed in cardiac tissue. There are three IP3R isoforms encoded by separate genes. In the heart, the IP3R-2 isoform is reported to being most predominant with regards to expression levels and functional significance. The functional roles of IP3R-1 and IP3R-3 in the heart are essentially unexplored despite measureable expression levels. Here we show that all three IP3Rs isoforms are expressed in both neonatal and adult rat ventricular cardiomyocytes, and in human heart tissue. The three IP3R proteins are expressed throughout the cardiomyocyte sarcoplasmic reticulum. Using isoform specific siRNA, we found that expression of all three IP3R isoforms are required for hypertrophic signaling downstream of endothelin-1 stimulation. Mechanistically, IP3Rs specifically contribute to activation of the hypertrophic program by mediating the positive inotropic effects of endothelin-1 and leading to downstream activation of nuclear factor of activated T-cells. Our findings highlight previously unidentified functions for IP3R isoforms in the heart with specific implications for hypertrophic signaling in animal models and in human disease.
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Affiliation(s)
- M Iveth Garcia
- Cell Biology Graduate Program, University of Texas Medical Branch, Galveston, TX 77555, United States; Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, TX 77030, United States
| | - Anja Karlstaedt
- Department of Internal Medicine, Division of Cardiology, McGovern Medical School at UTHealth, Houston, TX 77030, United States
| | - Jessica J Chen
- Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, TX 77030, United States
| | | | - Keith A Youker
- Houston Methodist Hospital, Houston, TX 77030, United States
| | - Heinrich Taegtmeyer
- Department of Internal Medicine, Division of Cardiology, McGovern Medical School at UTHealth, Houston, TX 77030, United States
| | - Darren Boehning
- Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, TX 77030, United States.
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7
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Huang J, Zhang M, Zhang P, Liang H, Ouyang K, Yang HT. Coupling switch of P2Y-IP3 receptors mediates differential Ca(2+) signaling in human embryonic stem cells and derived cardiovascular progenitor cells. Purinergic Signal 2016; 12:465-78. [PMID: 27098757 DOI: 10.1007/s11302-016-9512-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 04/04/2016] [Indexed: 12/18/2022] Open
Abstract
Purinergic signaling mediated by P2 receptors (P2Rs) plays important roles in embryonic and stem cell development. However, how it mediates Ca(2+) signals in human embryonic stem cells (hESCs) and derived cardiovascular progenitor cells (CVPCs) remains unclear. Here, we aimed to determine the role of P2Rs in mediating Ca(2+) mobilizations of these cells. hESCs were induced to differentiate into CVPCs by our recently established methods. Gene expression of P2Rs and inositol 1,4,5-trisphosphate receptors (IP3Rs) was analyzed by quantitative/RT-PCR. IP3R3 knockdown (KD) or IP3R2 knockout (KO) hESCs were established by shRNA- or TALEN-mediated gene manipulations, respectively. Confocal imaging revealed that Ca(2+) responses in CVPCs to ATP and UTP were more sensitive and stronger than those in hESCs. Consistently, the gene expression levels of most P2YRs except P2Y1 were increased in CVPCs. Suramin or PPADS blocked ATP-induced Ca(2+) transients in hESCs but only partially inhibited those in CVPCs. Moreover, the P2Y1 receptor-specific antagonist MRS2279 abolished most ATP-induced Ca(2+) signals in hESCs but not in CVPCs. P2Y1 receptor-specific agonist MRS2365 induced Ca(2+) transients only in hESCs but not in CVPCs. Furthermore, IP3R2KO but not IP3R3KD decreased the proportion of hESCs responding to MRS2365. In contrast, both IP3R2 and IP3R3 contributed to UTP-induced Ca(2+) responses while ATP-induced Ca(2+) responses were more dependent on IP3R2 in the CVPCs. In conclusion, a predominant role of P2Y1 receptors in hESCs and a transition of P2Y-IP3R coupling in derived CVPCs are responsible for the differential Ca(2+) mobilization between these cells.
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Affiliation(s)
- Jijun Huang
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, 200031, China.,Second Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310009, China
| | - Min Zhang
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, 200031, China
| | - Peng Zhang
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, 200031, China
| | - He Liang
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, 200031, China.,Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China
| | - Kunfu Ouyang
- Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
| | - Huang-Tian Yang
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, 200031, China. .,Second Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang, 310009, China. .,Translational Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China.
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8
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Hohendanner F, McCulloch AD, Blatter LA, Michailova AP. Calcium and IP3 dynamics in cardiac myocytes: experimental and computational perspectives and approaches. Front Pharmacol 2014; 5:35. [PMID: 24639654 PMCID: PMC3944219 DOI: 10.3389/fphar.2014.00035] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/18/2014] [Indexed: 11/22/2022] Open
Abstract
Calcium plays a crucial role in excitation-contraction coupling (ECC), but it is also a pivotal second messenger activating Ca2+-dependent transcription factors in a process termed excitation-transcription coupling (ETC). Evidence accumulated over the past decade indicates a pivotal role of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release in the regulation of cytosolic and nuclear Ca2+ signals. IP3 is generated by stimulation of plasma membrane receptors that couple to phospholipase C (PLC), liberating IP3 from phosphatidylinositol 4,5-bisphosphate (PIP2). An intriguing aspect of IP3 signaling is the presence of the entire PIP2-PLC-IP3 signaling cascade as well as the presence of IP3Rs at the inner and outer membranes of the nuclear envelope (NE) which functions as a Ca2+ store. The observation that the nucleus is surrounded by its own putative Ca2+ store raises the possibility that nuclear IP3-dependent Ca2+ release plays a critical role in ETC. This provides a potential mechanism of regulation that acts locally and autonomously from the global cytosolic Ca2+ signal underlying ECC. Moreover, there is evidence that: (i) the sarcoplasmic reticulum (SR) and NE are a single contiguous Ca2+ store; (ii) the nuclear pore complex is the major gateway for Ca2+ and macromolecules to pass between the cytosol and the nucleoplasm; (iii) the inner membrane of the NE hosts key Ca2+ handling proteins including the Na+/Ca2+ exchanger (NCX)/GM1 complex, ryanodine receptors (RyRs), nicotinic acid adenine dinucleotide phosphate receptors (NAADPRs), Na+/K+ ATPase, and Na+/H+ exchanger. Thus, it appears that the nucleus represents a Ca2+ signaling domain equipped with its own ion channels and transporters that allow for complex local Ca2+ signals. Many experimental and modeling approaches have been used for the study of intracellular Ca2+ signaling but the key to the understanding of the dual role of Ca2+ mediating ECC and ECT lays in quantitative differences of local [Ca2+] in the nuclear and cytosolic compartment. In this review, we discuss the state of knowledge regarding the origin and the physiological implications of nuclear Ca2+ transients in different cardiac cell types (adult atrial and ventricular myocytes) as well as experimental and mathematical approaches to study Ca2+ and IP3 signaling in the cytosol and nucleus. In particular, we focus on the concept that highly localized Ca2+ signals are required to translocate and activate Ca2+-dependent transcription factors (e.g., nuclear factor of activated T-cells, NFAT; histone deacetylase, HDAC) through phosphorylation/dephosphorylation processes.
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Affiliation(s)
- Felix Hohendanner
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA
| | - Lothar A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
| | - Anushka P Michailova
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA
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Cooley N, Ouyang K, McMullen JR, Kiriazis H, Sheikh F, Wu W, Mu Y, Du XJ, Chen J, Woodcock EA. No contribution of IP3-R(2) to disease phenotype in models of dilated cardiomyopathy or pressure overload hypertrophy. Circ Heart Fail 2012; 6:318-25. [PMID: 23258573 DOI: 10.1161/circheartfailure.112.972158] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We investigated the contribution of inositol(1,4,5)-trisphosphate (Ins(1,4,5)P3 [IP3]) receptors (IP3-R) to disease progression in mouse models of dilated cardiomyopathy (DCM) and pressure overload hypertrophy. Mice expressing mammalian sterile 20-like kinase and dominant-negative phosphatidylinositol-3-kinase in heart (Mst1×dn-PI3K-2Tg; DCM-2Tg) develop severe DCM and conduction block, associated with increased expression of type 2 IP3-R (IP3-R(2)) and heightened generation of Ins(1,4,5)P3. Similar increases in Ins(1,4,5)P3 and IP3-R(2) are caused by transverse aortic constriction. METHODS AND RESULTS To evaluate the contribution of IP3-R(2) to disease progression, the DCM-2Tg mice were further crossed with mice in which the type 2 IP3-R (IP3-R(2)-/-) had been deleted (DCM-2Tg×IP3-R(2)-/-) and transverse aortic constriction was performed on IP3-R(2)-/- mice. Hearts from DCM-2Tg mice and DCM-2Tg×IP3-R(2)-/- were similar in terms of chamber dilatation, atrial enlargement, and ventricular wall thinning. Electrophysiological changes were also similar in the DCM-2Tg mice, with and without IP3-R(2). Deletion of IP3-R(2) did not alter the progression of heart failure, because DCM-2Tg mice with and without IP3-R(2) had similarly reduced contractility, increased lung congestion, and atrial thrombus, and both strains died between 10 and 12 weeks of age. Loss of IP3-R(2) did not alter the progression of hypertrophy after transverse aortic constriction. CONCLUSIONS We conclude that IP3-R(2) do not contribute to the progression of DCM or pressure overload hypertrophy, despite increased expression and heightened generation of the ligand, Ins(1,4,5)P3.
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Affiliation(s)
- Nicola Cooley
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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10
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Wong A, Grubb DR, Cooley N, Luo J, Woodcock EA. Regulation of autophagy in cardiomyocytes by Ins(1,4,5)P(3) and IP(3)-receptors. J Mol Cell Cardiol 2012; 54:19-24. [PMID: 23137780 DOI: 10.1016/j.yjmcc.2012.10.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 10/19/2012] [Accepted: 10/24/2012] [Indexed: 12/11/2022]
Abstract
Autophagy is a process that removes damaged proteins and organelles and is of particular importance in terminally differentiated cells such as cardiomyocytes, where it has primarily a protective role. We investigated the involvement of inositol(1,4,5)trisphosphate (Ins(1,4,5)P(3)) and its receptors in autophagic responses in neonatal rat ventricular myocytes (NRVM). Treatment with the IP(3)-receptor (IP(3)-R) antagonist 2-aminoethoxydiphenyl borate (2-APB) at 5 or 20 μmol/L resulted in an increase in autophagosome content, defined as puncta labeled by antibody to microtubule associated light chain 3 (LC3). 2-APB also increased autophagic flux, indicated by heightened LC3II accumulation, which was further enhanced by bafilomycin (10nmol/L). Expression of Ins(1,4,5)P(3) 5-phosphatase (IP(3)-5-Pase) to deplete Ins(1,4,5)P(3) also increased LC3-labeled puncta and LC3II content, suggesting that Ins(1,4,5)P(3) inhibits autophagy. The IP(3)-R can act as an inhibitory scaffold sequestering the autophagic effector, beclin-1 to its ligand binding domain (LBD). Expression of GFP-IP(3)-R-LBD inhibited autophagic signaling and furthermore, beclin-1 co-immunoprecipitated with the IP(3)-R-LBD. A mutant GFP-IP(3)-R-LBD with reduced ability to bind Ins(1,4,5)P(3) bound beclin-1 and inhibited autophagy similarly to the wild type sequence. These data provide evidence that Ins(1,4,5)P(3) and IP(3)-R act as inhibitors of autophagic responses in cardiomyocytes. By suppressing autophagy, IP(3)-R may contribute to cardiac pathology.
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Affiliation(s)
- Albert Wong
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, Victoria 3004, Australia
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11
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Inositol 1,4,5-trisphosphate receptors and pacemaker rhythms. J Mol Cell Cardiol 2012; 53:375-81. [PMID: 22713798 DOI: 10.1016/j.yjmcc.2012.06.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 06/08/2012] [Indexed: 11/21/2022]
Abstract
Intracellular Ca(2+) plays an important role in the control of the heart rate through the interaction between Ca(2+) release by ryanodine receptors in the sarcoplasmic reticulum (SR) and the extrusion of Ca(2+) by the sodium-calcium exchanger which generates an inward current. A second type of SR Ca(2+) release channel, the inositol 1,4,5-trisphosphate receptor (IP(3)R), can release Ca(2+) from SR stores in many cell types, including cardiac myocytes. However, it is still uncertain whether IP(3)Rs play any functional role in regulating the heart rate. Accumulated evidence shows that IP(3) and IP(3)R are involved in rhythm control in non-cardiac pacemaker tissues and in the embryonic heart. In this review we focus on intracellular Ca(2+) oscillations generated by Ca(2+) release from IP(3)R that initiates membrane depolarization and provides a common mechanism producing spontaneous activity in a range of cells with pacemaker function. Emerging new evidence also suggests that IP(3)/IP(3)Rs play a functional role in normal and diseased hearts and in cardiac rhythm control. Several membrane currents, including a store-operated Ca(2+) current, might be activated by Ca(2+) release from IP(3)Rs. IP(3)/IP(3)R may thus add another dimension to the complex regulation of heart rate.
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Bootman MD, Smyrnias I, Thul R, Coombes S, Roderick HL. Atrial cardiomyocyte calcium signalling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:922-34. [DOI: 10.1016/j.bbamcr.2011.01.030] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 01/21/2011] [Accepted: 01/25/2011] [Indexed: 11/25/2022]
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13
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Atrial local Ca2+ signaling and inositol 1,4,5-trisphosphate receptors. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:59-70. [DOI: 10.1016/j.pbiomolbio.2010.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 01/18/2010] [Accepted: 02/18/2010] [Indexed: 11/24/2022]
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14
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Nakayama H, Bodi I, Maillet M, DeSantiago J, Domeier TL, Mikoshiba K, Lorenz JN, Blatter LA, Bers DM, Molkentin JD. The IP3 receptor regulates cardiac hypertrophy in response to select stimuli. Circ Res 2010; 107:659-66. [PMID: 20616315 DOI: 10.1161/circresaha.110.220038] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
RATIONALE Inositol 1,4,5-trisphosphate (IP(3)) is a second messenger that regulates intracellular Ca(2+) release through IP(3) receptors located in the sarco(endo)plasmic reticulum of cardiac myocytes. Many prohypertrophic G protein-coupled receptor (GPCR) signaling events lead to IP(3) liberation, although its importance in transducing the hypertrophic response has not been established in vivo. OBJECTIVE Here, we generated conditional, heart-specific transgenic mice with both gain- and loss-of-function for IP(3) receptor signaling to examine its hypertrophic growth effects following pathological and physiological stimulation. METHODS AND RESULTS Overexpression of the mouse type-2 IP(3) receptor (IP(3)R2) in the heart generated mild baseline cardiac hypertrophy at 3 months of age. Isolated myocytes from overexpressing lines showed increased Ca(2+) transients and arrhythmias in response to endothelin-1 stimulation. Although low levels of IP(3)R2 overexpression failed to augment/synergize cardiac hypertrophy following 2 weeks of pressure-overload stimulation, such levels did enhance hypertrophy following 2 weeks of isoproterenol infusion, in response to Galphaq overexpression, and/or in response to exercise stimulation. To inhibit IP(3) signaling in vivo, we generated transgenic mice expressing an IP(3) chelating protein (IP(3)-sponge). IP(3)-sponge transgenic mice abrogated cardiac hypertrophy in response to isoproterenol and angiotensin II infusion but not pressure-overload stimulation. Mechanistically, IP(3)R2-enhanced cardiac hypertrophy following isoproterenol infusion was significantly reduced in the calcineurin-Abeta-null background. CONCLUSION These results indicate that IP(3)-mediated Ca(2+) release plays a central role in regulating cardiac hypertrophy downstream of GPCR signaling, in part, through a calcineurin-dependent mechanism.
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Affiliation(s)
- Hiroyuki Nakayama
- Howard Hughes Medical Institute, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, Cincinnati, OH 45229-3039, USA
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15
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Kim JC, Son MJ, Subedi KP, Kim DH, Woo SH. IP3-induced cytosolic and nuclear Ca2+ signals in HL-1 atrial myocytes: possible role of IP3 receptor subtypes. Mol Cells 2010; 29:387-95. [PMID: 20213315 DOI: 10.1007/s10059-010-0039-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 11/30/2009] [Accepted: 12/07/2009] [Indexed: 10/19/2022] Open
Abstract
HL-1 cells are the adult cardiac cell lines available that continuously divide while maintaining an atrial phenotype. Here we examined the expression and localization of inositol 1,4,5-trisphosphate receptor (IP(3)R) subtypes, and investigated how pattern of IP(3)-induced subcellular local Ca(2+) signaling is encoded by multiple IP(3)R subtypes in HL-1 cells. The type 1 IP(3)R (IP(3)R1) was expressed in the perinucleus with a diffuse pattern and the type 2 IP(3)R (IP(3)R2) was expressed in the cytosol with a punctate distribution. Extracellular ATP (1 mM) elicited transient intracellular Ca(2+) releases accompanied by a Ca(2+) oscillation, which was eliminated by the blocker of IP(3)Rs, 2-APB, and attenuated by ryanodine. Direct introduction of IP(3) into the permeabilized cells induced Ca(2+) transients with Ca(2+) oscillations at [Symbol: see text] 20 muM of IP(3), which was removed by the inhibition of IP(3)Rs using 2-APB and heparin. IP(3)-induced local Ca(2+) transients contained two distinct time courses: a rapid oscillation and a monophasic Ca(2+) transient. The magnitude of Ca(2+) oscillation was significantly larger in the cytosol than in the nucleus, while the monophasic Ca(2+) transient was more pronounced in the nucleus. These results provide evidence for the molecular and functional expression of IP(3)R1 and IP(3)R2 in HL-1 cells, and suggest that such distinct local Ca(2+) signaling may be correlated with the punctate distribution of IP(3)R2s in the cytosol and the diffuse localization of IP(3)R1 in the peri-nucleus.
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MESH Headings
- Adenosine Triphosphate/pharmacology
- Animals
- Blotting, Western
- Calcium/metabolism
- Calcium Signaling/drug effects
- Cell Line
- Cell Nucleus/metabolism
- Cells, Cultured
- Cytosol/metabolism
- Dose-Response Relationship, Drug
- Heart Atria/cytology
- Immunohistochemistry
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Male
- Mice
- Microscopy, Confocal
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Isoforms/physiology
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Time Factors
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Affiliation(s)
- Joon-Chul Kim
- College of Pharmacy, IDRD, Chungnam National University, Daejeon, 305-764, Korea
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16
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Sedan O, Dolnikov K, Zeevi-Levin N, Fleishmann N, Spiegel I, Berdichevski S, Amit M, Itskovitz-Eldor J, Binah O. Human embryonic stem cell-derived cardiomyocytes can mobilize 1,4,5-inositol trisphosphate-operated [Ca2+]i stores. Ann N Y Acad Sci 2010; 1188:68-77. [DOI: 10.1111/j.1749-6632.2009.05085.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Cooper Z, Greenwood M, Mazzag B. A computational analysis of localized Ca2+-dynamics generated by heterogeneous release sites. Bull Math Biol 2009; 71:1543-79. [PMID: 19440797 DOI: 10.1007/s11538-009-9413-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 02/10/2009] [Indexed: 11/30/2022]
Abstract
We investigate the role of heterogeneous expression of IP3R and RyR in generating diverse elementary Ca2+ signals. It has been shown empirically (Wojcikiewicz and Luo in Mol. Pharmacol. 53(4):656-662, 1998; Newton et al. in J. Biol. Chem. 269(46):28613-28619, 1994; Smedt et al. in Biochem. J. 322(Pt. 2):575-583, 1997) that tissues express various proportions of IP3 and RyR isoforms and this expression is dynamically regulated (Parrington et al. in Dev. Biol. 203(2):451-461, 1998; Fissore et al. in Biol. Reprod. 60(1):49-57, 1999; Tovey et al. in J. Cell Sci. 114(Pt. 22):3979-3989, 2001). Although many previous theoretical studies have investigated the dynamics of localized calcium release sites (Swillens et al. in Proc. Natl. Acad. Sci. U.S.A. 96(24):13750-13755, 1999; Shuai and Jung in Proc. Natl. Acad. Sci. U.S.A. 100(2):506-510, 2003a; Shuai and Jung in Phys. Rev. E, Stat. Nonlinear Soft Matter Phys. 67(3 Pt. 1):031905, 2003b; Thul and Falcke in Biophys. J. 86(5):2660-2673, 2004; DeRemigio and Smith in Cell Calcium 38(2):73-86, 2005; Nguyen et al. in Bull. Math. Biol. 67(3):393-432, 2005), so far all such studies focused on release sites consisting of identical channel types. We have extended an existing mathematical model (Nguyen et al. in Bull. Math. Biol. 67(3):393-432, 2005) to release sites with two (or more) receptor types, each with its distinct channel kinetics. Mathematically, the release site is represented by a transition probability matrix for a collection of nonidentical stochastically gating channels coupled through a shared Ca2+ domain. We demonstrate that under certain conditions a previously defined mean-field approximation of the coupling strength does not accurately reproduce the release site dynamics. We develop a novel approximation and establish that its performance in these instances is superior. We use this mathematical framework to study the effect of heterogeneity in the Ca2+-regulation of two colocalized channel types on the release site dynamics. We consider release sites consisting of channels with both Ca2+-activation and inactivation ("four-state channels") and channels with Ca2+-activation only ("two-state channels") and show that for the appropriate parameter values, synchronous channel openings within a release site with any proportion of two-state to four-state channels are possible, however, the larger the proportion of two-state channels, the more sensitive the dynamics are to the exact spatial positioning of the channels and the distance between channels. Specifically, the clustering of even a small number of two-state channels interferes with puff/spark termination and increases puff durations or leads to a tonic response.
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Affiliation(s)
- Zachary Cooper
- Department of Mathematics, Humboldt State University, Arcata, CA 95521, USA
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18
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Michalak M, Opas M. Endoplasmic and sarcoplasmic reticulum in the heart. Trends Cell Biol 2009; 19:253-9. [PMID: 19409791 DOI: 10.1016/j.tcb.2009.03.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 03/21/2009] [Accepted: 03/23/2009] [Indexed: 12/30/2022]
Abstract
The concept of the presence of sarcoplasmic reticulum (SR) membrane in the heart is widely accepted and has been considered merely to be a different name for the endoplasmic reticulum (ER) in muscle tissues. Cardiac SR membranes are specialized in the regulation of Ca(2+) transport and control of excitation-contraction coupling. By contrast, the ER is responsible for protein synthesis, modification, secretion, lipid and steroid synthesis, and modulation of Ca(2+) signaling. Recent developments have indicated that functional changes in proteins or pathways normally associated with ER and not SR membrane impact cardiac development and pathology. Here, we propose that the SR and ER might be functionally distinct internal membrane compartments in cardiomyocytes.
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Affiliation(s)
- Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
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19
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Balijepalli RC, Kamp TJ. Caveolae, ion channels and cardiac arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:149-60. [PMID: 19351512 DOI: 10.1016/j.pbiomolbio.2009.01.012] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Caveolae are specialized membrane microdomains enriched in cholesterol and sphingolipids which are present in multiple cell types including cardiomyocytes. Along with the essential scaffolding protein caveolin-3, a number of different ion channels and transporters have been localized to caveolae in cardiac myocytes including L-type Ca2+ channels (Ca(v)1.2), Na+ channels (Na(v)1.5), pacemaker channels (HCN4), Na+/Ca2+ exchanger (NCX1) and others. Closely associated with these channels are specific macromolecular signaling complexes that provide highly localized regulation of the channels. Mutations in the caveolin-3 gene (CAV3) have been linked with the congenital long QT syndrome (LQT9), and mutations in caveolar-localized ion channels may contribute to other inherited arrhythmias. Changes in the caveolar microdomain in acquired heart disease may also lead to dysregulation and dysfunction of ion channels, altering the risk of arrhythmias in conditions such as heart failure. This review highlights the existing evidence identifying and characterizing ion channels localized to caveolae in cardiomyocytes and their role in arrhythmogenesis.
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI 53792, USA
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20
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Katz G, Arad M, Eldar M. Catecholaminergic polymorphic ventricular tachycardia from bedside to bench and beyond. Curr Probl Cardiol 2009; 34:9-43. [PMID: 19068246 DOI: 10.1016/j.cpcardiol.2008.09.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a primary electrical myocardial disease characterized by exercise- and stress-related ventricular tachycardia manifested as syncope and sudden death. The disease has a heterogeneous genetic basis, with mutations in the cardiac Ryanodine Receptor channel (RyR2) gene accounting for an autosomal-dominant form (CPVT1) in approximately 50% and mutations in the cardiac calsequestrin gene (CASQ2) accounting for an autosomal-recessive form (CPVT2) in up to 2% of CPVT cases. Both RyR2 and calsequestrin are important participants in the cardiac cellular calcium homeostasis. We review the physiology of the cardiac calcium homeostasis, including the cardiac excitation contraction coupling and myocyte calcium cycling. The pathophysiology of cardiac arrhythmias related to myocyte calcium handling and the effects of different modulators are discussed. The putative derangements in myocyte calcium homeostasis responsible for CPVT, as well as the clinical manifestations and therapeutic options available, are described.
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21
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Diwan A, Matkovich SJ, Yuan Q, Zhao W, Yatani A, Brown JH, Molkentin JD, Kranias EG, Dorn GW. Endoplasmic reticulum-mitochondria crosstalk in NIX-mediated murine cell death. J Clin Invest 2008; 119:203-12. [PMID: 19065046 DOI: 10.1172/jci36445] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 10/15/2008] [Indexed: 01/09/2023] Open
Abstract
Transcriptional upregulation of the proapoptotic BCL2 family protein NIX limits red blood cell formation and can cause heart failure by inducing cell death, but the requisite molecular events are poorly defined. Here, we show complementary mechanisms for NIX-mediated cell death involving direct and ER/sarcoplasmic reticulum-mediated (ER/SR-mediated) mitochondria disruption. Endogenous cardiac NIX and recombinant NIX localize both to the mitochondria and to the ER/SR. In genetic mouse models, cardiomyocyte ER/SR calcium stores are proportional to the level of expressed NIX. Whereas Nix ablation was protective in a mouse model of apoptotic cardiomyopathy, genetic correction of the decreased SR calcium content of Nix-null mice restored sensitivity to cell death and reestablished cardiomyopathy. Nix mutants specific to ER/SR or mitochondria activated caspases and were equally lethal, but only ER/SR-Nix caused loss of the mitochondrial membrane potential. These results establish a new function for NIX as an integrator of transcriptional and calcium-mediated signals for programmed cell death.
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Affiliation(s)
- Abhinav Diwan
- Center for Pharmacogenomics, Washington University in St. Louis, St. Louis, MO 63110, USA
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22
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Vasilevski O, Grubb DR, Filtz TM, Yang S, McLeod-Dryden TJ, Luo J, Karna D, Chen J, Woodcock EA. Ins(1,4,5)P3 regulates phospholipase Cβ1 expression in cardiomyocytes. J Mol Cell Cardiol 2008; 45:679-84. [DOI: 10.1016/j.yjmcc.2008.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/18/2008] [Accepted: 07/07/2008] [Indexed: 11/16/2022]
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23
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Oestreich EA, Malik S, Goonasekera SA, Blaxall BC, Kelley GG, Dirksen RT, Smrcka AV. Epac and phospholipase Cepsilon regulate Ca2+ release in the heart by activation of protein kinase Cepsilon and calcium-calmodulin kinase II. J Biol Chem 2008; 284:1514-22. [PMID: 18957419 DOI: 10.1074/jbc.m806994200] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently, we identified a novel signaling pathway involving Epac, Rap, and phospholipase C (PLC)epsilon that plays a critical role in maximal beta-adrenergic receptor (betaAR) stimulation of Ca2+-induced Ca2+ release (CICR) in cardiac myocytes. Here we demonstrate that PLCepsilon phosphatidylinositol 4,5-bisphosphate hydrolytic activity and PLCepsilon-stimulated Rap1 GEF activity are both required for PLCepsilon-mediated enhancement of sarcoplasmic reticulum Ca2+ release and that PLCepsilon significantly enhances Rap activation in response to betaAR stimulation in the heart. Downstream of PLCepsilon hydrolytic activity, pharmacological inhibition of PKC significantly inhibited both betaAR- and Epac-stimulated increases in CICR in PLCepsilon+/+ myocytes but had no effect in PLCepsilon-/- myocytes. betaAR and Epac activation caused membrane translocation of PKCepsilon in PLCepsilon+/+ but not PLCepsilon-/- myocytes and small interfering RNA-mediated PKCepsilon knockdown significantly inhibited both betaAR and Epac-mediated CICR enhancement. Further downstream, the Ca2+/calmodulin-dependent protein kinase II (CamKII) inhibitor, KN93, inhibited betaAR- and Epac-mediated CICR in PLCepsilon+/+ but not PLCepsilon-/- myocytes. Epac activation increased CamKII Thr286 phosphorylation and enhanced phosphorylation at CamKII phosphorylation sites on the ryanodine receptor (RyR2) (Ser2815) and phospholamban (Thr17) in a PKC-dependent manner. Perforated patch clamp experiments revealed that basal and betaAR-stimulated peak L-type current density are similar in PLCepsilon+/+ and PLCepsilon-/- myocytes suggesting that control of sarcoplasmic reticulum Ca2+ release, rather than Ca2+ influx through L-type Ca2+ channels, is the target of regulation of a novel signal transduction pathway involving sequential activation of Epac, PLCepsilon, PKCepsilon, and CamKII downstream of betaAR activation.
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Affiliation(s)
- Emily A Oestreich
- Department of Pharmacology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
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24
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Abstract
Arrhythmias arise from a complex interaction between structural changes in the myocardium and changes in cellular electrophysiology. Electrophysiological balance requires precise control of sarcolemmal ion channels and exchangers, many of which are regulated by phospholipid, phosphatidylinositol(4,5)bisphosphate. Phosphatidylinositol(4,5)bisphosphate is the immediate precursor of inositol(1,4,5)trisphosphate, a regulator of intracellular Ca2+ signalling and, therefore, a potential contributor to arrhythmogenesis by altering Ca2+ homeostasis. The aim of the present review is to outline current evidence that this signalling pathway can be a player in the initiation or maintenance of arrhythmias.
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Affiliation(s)
- Elizabeth A Woodcock
- Molecular Cardiology Laboratory, Baker IDI Heart and Diabetes Institute, PO Box 6492, St Kilda Road Central, Melbourne, 8008 Victoria, Australia.
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25
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Sedan O, Dolnikov K, Zeevi-Levin N, Leibovich N, Amit M, Itskovitz-Eldor J, Binah O. 1,4,5-Inositol trisphosphate-operated intracellular Ca(2+) stores and angiotensin-II/endothelin-1 signaling pathway are functional in human embryonic stem cell-derived cardiomyocytes. Stem Cells 2008; 26:3130-8. [PMID: 18818435 DOI: 10.1634/stemcells.2008-0777] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
On the basis of previous findings suggesting that in human embryonic stem cell-derived cardiomyocytes (hESC-CM) the sarcoplasmic reticulum Ca(2+)-induced release of calcium machinery is either absent or immature, in the present study we tested the hypothesis that hESC-CM contain fully functional 1,4,5-inositol trisphosphate (1,4,5-IP(3))-operated intracellular Ca(2+) ([Ca(2+)](i)) stores that can be mobilized upon appropriate physiological stimuli. To test this hypothesis we investigated the effects of angiotensin-II (AT-II) and endothelin-1 (ET-1), which activate the 1,4,5-IP(3) pathway, on [Ca(2+)](i) transients and contractions in beating clusters of hESC-CM. Our major findings were that in paced hESC-CM both AT-II and ET-1 (10(-9) to 10(-7) M) increased the contraction amplitude and the maximal rates of contraction and relaxation. In addition, AT-II (10(-9) to 10(-7) M) increased the [Ca(2+)](i) transient amplitude. The involvement of 1,4,5-IP(3)-dependent intracellular Ca(2+) release in the inotropic effect of AT-II was supported by the findings that (a) hESC-CM express AT-II, ET-1, and 1,4,5-IP(3) receptors determined by immunofluorescence staining, and (b) the effects of AT-II were blocked by 2 microM 2-aminoethoxyphenyl borate (a 1,4,5-IP(3) receptor blocker) and U73122 (a phospholipase C blocker). In conclusion, these findings demonstrate for the first time that hESC-CM exhibit functional AT-II and ET-1 signaling pathways, as well as 1,4,5-IP(3)-operated releasable Ca(2+) stores.
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Affiliation(s)
- Oshra Sedan
- Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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26
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Domeier TL, Zima AV, Maxwell JT, Huke S, Mignery GA, Blatter LA. IP3 receptor-dependent Ca2+ release modulates excitation-contraction coupling in rabbit ventricular myocytes. Am J Physiol Heart Circ Physiol 2007; 294:H596-604. [PMID: 18055509 DOI: 10.1152/ajpheart.01155.2007] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-dependent Ca(2+) signaling exerts positive inotropic, but also arrhythmogenic, effects on excitation-contraction coupling (ECC) in the atrial myocardium. The role of IP(3)R-dependent sarcoplasmic reticulum (SR) Ca(2+) release in ECC in the ventricular myocardium remains controversial. Here we investigated the role of this signaling pathway during ECC in isolated rabbit ventricular myocytes. Immunoblotting of proteins from ventricular myocytes showed expression of both type 2 and type 3 IP(3)R at levels approximately 3.5-fold less than in atrial myocytes. In permeabilized myocytes, direct application of IP(3) (10 microM) produced a transient 21% increase in the frequency of Ca(2+) sparks (P < 0.05). This increase was accompanied by a 13% decrease in spark amplitude (P < 0.05) and a 7% decrease in SR Ca(2+) load (P < 0.05) and was inhibited by IP(3)R antagonists 2-aminoethoxydiphenylborate (2-APB; 20 microM) and heparin (0.5 mg/ml). In intact myocytes endothelin-1 (100 nM) was used to stimulate IP(3) production and caused a 38% (P < 0.05) increase in the amplitude of action potential-induced (0.5 Hz, field stimulation) Ca(2+) transients. This effect was abolished by the IP(3)R antagonist 2-APB (2 microM) or by using adenoviral expression of an IP(3) affinity trap that buffers cellular IP(3). Together, these data suggest that in rabbit ventricular myocytes IP(3)R-dependent Ca(2+) release has positive inotropic effects on ECC by facilitating Ca(2+) release through ryanodine receptor clusters.
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Affiliation(s)
- Timothy L Domeier
- Department of Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
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27
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Wen Y, Cui W, Liu P. Type I inositol 1, 4, 5-triphosphate receptors increase in kidney of mice with fulminant hepatic failure. World J Gastroenterol 2007; 13:2344-8. [PMID: 17511035 PMCID: PMC4147145 DOI: 10.3748/wjg.v13.i16.2344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To delineate the mechanisms of renal vasocon-striction in hepatorenal syndrome (HRS), we investigated the expression of typeIinositol 1, 4, 5-triphosphate receptors (IP3RI) of kidney in mice with fulminant hepatic failure (FHF).
METHODS: FHF was induced by lipopolysaccharide (LPS) in D-galactosamine (GalN) sensitized BALB/c mice. There were 20 mice in normal saline (NS)-treated group, 20 mice in LPS-treated group, 20 mice in GalN-treated group, and 60 mice in GalN/LPS-treated group (FHF group). Liver and kidney tissues were obtained at 2, 6, and 9 h after administration. The liver and kidney specimens were stained with hematoxylin-eosin for studying morphological changes under light microscope. The expression of IP3RIin kidney tissue was tested by immunohistochemistry, Western blot and reverse transcription (RT)-PCR.
RESULTS: Kidney tissues were morphologically normal at all time points in all groups. IP3RIproteins were found localized in the plasma region of glomerular mesangial cells (GMC) and vascular smooth muscle cells (VSMC) in kidney by immunohistochemical staining. In kidney of mice with FHF at 6 h and 9 h IP3RIstaining was up-regulated. Results from Western blot demonstrated consistent and significant increment of IP3RIexpression in mice with FHF at 6 h and 9 h (t = 3.16, P < 0.05; t = 5.43, P < 0.01). Furthermore, we evaluated IP3RImRNA expression by RT-PCR and observed marked up-regulation of IP3RImRNA in FHF samples at 2 h, 6 h and 9 h compared to controls (t = 2.97, P < 0.05; t = 4.42, P < 0.01; t = 3.81, P < 0.01).
CONCLUSION: The expression of IP3RIprotein increased in GMC and renal VSMC of mice with FHF, possibly caused by up-regulation of IP3RImRNA.
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MESH Headings
- Animals
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Disease Models, Animal
- Disease Progression
- Galactosamine
- Glomerular Mesangium/metabolism
- Glomerular Mesangium/pathology
- Hepatorenal Syndrome/metabolism
- Hepatorenal Syndrome/pathology
- Inositol 1,4,5-Trisphosphate Receptors
- Kidney/metabolism
- Kidney/pathology
- Lipopolysaccharides
- Liver Failure, Acute/chemically induced
- Liver Failure, Acute/metabolism
- Liver Failure, Acute/pathology
- Male
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred BALB C
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Up-Regulation
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Affiliation(s)
- Ying Wen
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, No. 155 Nanjing North Street, Shenyang 110001, Liaoning Province, China
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Roderick HL, Bootman MD. Pacemaking, arrhythmias, inotropy and hypertrophy: the many possible facets of IP3 signalling in cardiac myocytes. J Physiol 2007; 581:883-4. [PMID: 17446217 PMCID: PMC2170819 DOI: 10.1113/jphysiol.2007.133819] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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29
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Goel M, Zuo CD, Sinkins WG, Schilling WP. TRPC3 channels colocalize with Na+/Ca2+exchanger and Na+pump in axial component of transverse-axial tubular system of rat ventricle. Am J Physiol Heart Circ Physiol 2007; 292:H874-83. [PMID: 17012351 DOI: 10.1152/ajpheart.00785.2006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transient receptor potential canonical (TRPC) proteins form Ca2+-permeable, nonselective cation channels activated after stimulation of G protein-coupled membrane receptors linked to phospholipase C (PLC). Although the PLC/inositol phosphate signaling pathway is known to exist in heart, expression and subcellular distribution of TRPC channel proteins in ventricular myocardium have not been evaluated. Of the six members of the TRPC channel family examined here, only TRPC3 was found by Western blot analysis of membrane proteins from rodent or canine ventricle. Likewise, only TRPC3 was observed in immunofluorescence analysis of thin sections from rat ventricle. TRPC3 was also the only family member observed in neonatal rat ventricular myocytes in culture. In longitudinal sections of rat ventricle, TRPC3 was predominantly localized to the intercalated disk region of the myocyte. However, transverse sections through heart muscle or single isolated adult myocytes revealed TRPC3-specific labeling in a vast network of intracellular membranes, where it colocalized with the Na+-K+-ATPase (NKA) pump and the Na+/Ca2+exchanger (NCX) but not with the ryanodine receptor or the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pump. Reciprocal immunoprecipitation assays from rat or canine ventricle showed that TRPC3 associates with NKA and NCX but not with the plasmalemmal Ca2+-ATPase pump. Immunoprecipitations from Sf9 insect cells heterologously expressing TRPC3, NKA, and NCX in various combinations revealed that NKA and NCX interact and that TRPC3 and NCX interact, but that TRPC3 does not directly associate with NKA. Together, these results suggest that TRPC3 is localized in the ventricular myocyte to the axial component of the transverse-axial tubular system, where it exists in a signaling complex that includes NCX and NKA.
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Affiliation(s)
- Monu Goel
- Rammelkamp Center for Education and Research, Rm. R-322, MetroHealth Medical Center, 2500 MetroHealth Dr., Cleveland OH 44109-1998, USA
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30
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Onohara N, Nishida M, Inoue R, Kobayashi H, Sumimoto H, Sato Y, Mori Y, Nagao T, Kurose H. TRPC3 and TRPC6 are essential for angiotensin II-induced cardiac hypertrophy. EMBO J 2006; 25:5305-16. [PMID: 17082763 PMCID: PMC1636614 DOI: 10.1038/sj.emboj.7601417] [Citation(s) in RCA: 312] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Accepted: 10/11/2006] [Indexed: 12/28/2022] Open
Abstract
Angiotensin (Ang) II participates in the pathogenesis of heart failure through induction of cardiac hypertrophy. Ang II-induced hypertrophic growth of cardiomyocytes is mediated by nuclear factor of activated T cells (NFAT), a Ca(2+)-responsive transcriptional factor. It is believed that phospholipase C (PLC)-mediated production of inositol-1,4,5-trisphosphate (IP(3)) is responsible for Ca(2+) increase that is necessary for NFAT activation. However, we demonstrate that PLC-mediated production of diacylglycerol (DAG) but not IP(3) is essential for Ang II-induced NFAT activation in rat cardiac myocytes. NFAT activation and hypertrophic responses by Ang II stimulation required the enhanced frequency of Ca(2+) oscillation triggered by membrane depolarization through activation of DAG-sensitive TRPC channels, which leads to activation of L-type Ca(2+) channel. Patch clamp recordings from single myocytes revealed that Ang II activated DAG-sensitive TRPC-like currents. Among DAG-activating TRPC channels (TRPC3, TRPC6, and TRPC7), the activities of TRPC3 and TRPC6 channels correlated with Ang II-induced NFAT activation and hypertrophic responses. These data suggest that DAG-induced Ca(2+) signaling pathway through TRPC3 and TRPC6 is essential for Ang II-induced NFAT activation and cardiac hypertrophy.
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Affiliation(s)
- Naoya Onohara
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka
| | - Motohiro Nishida
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka
| | - Ryuji Inoue
- Department of Physiology, School of Medicine, Fukuoka University, Jonan-ku, Fukuoka, Japan
| | - Hiroyuki Kobayashi
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka
| | - Hideki Sumimoto
- Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka, Japan
| | - Yoji Sato
- National Institute of Health Sciences, Setagaya, Tokyo, Japan
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Taku Nagao
- National Institute of Health Sciences, Setagaya, Tokyo, Japan
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Tel./Fax: +81 92 642 6884; E-mail:
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31
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Przyklenk K, Maynard M, Whittaker P. First molecular evidence that inositol trisphosphate signaling contributes to infarct size reduction with preconditioning. Am J Physiol Heart Circ Physiol 2006; 291:H2008-12. [PMID: 16731645 DOI: 10.1152/ajpheart.00313.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Considerable attention has focused on the role of protein kinase C (PKC) in triggering the profound infarct-sparing effect of ischemic preconditioning (PC). In contrast, the involvement of inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)], the second messenger generated in parallel with the diacylglycerol-PKC pathway, remains poorly understood. We hypothesized that, if Ins(1,4,5)P(3) signaling [i.e., release of Ins(1,4,5)P(3) and subsequent binding to Ins(1,4,5)P(3) receptors] contributes to PC-induced cardioprotection, then the reduction of infarct size achieved with PC would be attenuated in mice that are deficient in Ins(1,4,5)P(3) receptor protein. To test this concept, hearts were harvested from 1) B6C3Fe-a/a-Itpr-1(opt+/-)/J mutants displaying reduced expression of Ins(1,4,5)P(3) receptor-1 protein, 2) Itpr-1(opt+/+) wild types from the colony, and 3) C57BL/6J mice. All hearts were buffer-perfused and randomized to receive two 5-min episodes of PC ischemia, pretreatment with d-myo-Ins(1,4,5)P(3) [sodium salt of native Ins(1,4,5)P(3)], the mitochondrial ATP-sensitive K(+) channel opener diazoxide, or no intervention (controls). After the treatment phase, all hearts underwent 30-min global ischemia followed by 2 h of reperfusion, and infarct size was delineated by tetrazolium staining. In both wild-type and C57BL/6J cohorts, area of necrosis in hearts that received PC, d-myo-Ins(1,4,5)P(3), and diazoxide averaged 28-35% of the total left ventricle (LV), significantly smaller than the values of 52-53% seen in controls (P < 0.05). In contrast, in Itpr-1(opt+/-) mutants, protection was only seen with diazoxide: neither PC nor d-myo-Ins(1,4,5)P(3) limited infarct size (52-58% vs. 56% of the LV in mutant controls). These data provide novel evidence that Ins(1,4,5)P(3) signaling contributes to infarct size reduction with PC.
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MESH Headings
- Animals
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Diazoxide/pharmacology
- Gene Expression Regulation
- Heart Ventricles/drug effects
- Heart Ventricles/pathology
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate/physiology
- Inositol 1,4,5-Trisphosphate Receptors
- Ischemic Preconditioning, Myocardial/methods
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Myocardial Infarction/etiology
- Myocardial Infarction/pathology
- Myocardial Infarction/prevention & control
- Myocardium/metabolism
- Protein Kinase C/physiology
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Signal Transduction/physiology
- Vasodilator Agents/pharmacology
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Affiliation(s)
- Karin Przyklenk
- Dept. of Emergency Medicine, Univ. of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA 01655, USA.
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32
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Molkentin JD. Dichotomy of Ca2+ in the heart: contraction versus intracellular signaling. J Clin Invest 2006; 116:623-6. [PMID: 16511595 PMCID: PMC1386113 DOI: 10.1172/jci27824] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ca2+ plays a pivotal role in both excitation-contraction coupling (ECC) and activation of Ca2+-dependent signaling pathways. One of the remaining questions in cardiac biology is how Ca2+-dependent signaling pathways are regulated under conditions of continual Ca2+ transients that mediate cardiac contraction during each heartbeat. Ca2+-calmodulin-dependent protein kinase II (CaMKII) activation and its ability to regulate histone deacetylase 5 (HDAC5) nuclear shuttling represent a critical Ca2+-dependent signaling circuit for controlling cardiac hypertrophy and heart failure, yet the mechanism of activation by Ca2+ is not known. In this issue of the JCI, Wu et al. convincingly demonstrate that the inositol 1,4,5-trisphosphate receptor (InsP3R) is involved in local control of Ca2+ for activating CaMKII in the nuclear envelope of adult ventricular cardiac myocytes (see the related article beginning on page 675). The overall paradigm that is demonstrated is the best example of a molecular mechanism whereby signaling is directly regulated by a local Ca2+ pool that is disparate or geometrically insensitive to cytosolic Ca2+ underlying each contractile cycle.
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Affiliation(s)
- Jeffery D Molkentin
- Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio 45229, USA.
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