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Woltz RL, Zheng Y, Choi W, Ngo K, Trinh P, Ren L, Thai PN, Harris BJ, Han Y, Rouen KC, Mateos DL, Jian Z, Chen-Izu Y, Dickson EJ, Yamoah EN, Yarov-Yarovoy V, Vorobyov I, Zhang XD, Chiamvimonvat N. Atomistic mechanisms of the regulation of small-conductance Ca 2+-activated K + channel (SK2) by PIP2. Proc Natl Acad Sci U S A 2024; 121:e2318900121. [PMID: 39288178 DOI: 10.1073/pnas.2318900121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 06/24/2024] [Indexed: 09/19/2024] Open
Abstract
Small-conductance Ca2+-activated K+ channels (SK, KCa2) are gated solely by intracellular microdomain Ca2+. The channel has emerged as a therapeutic target for cardiac arrhythmias. Calmodulin (CaM) interacts with the CaM binding domain (CaMBD) of the SK channels, serving as the obligatory Ca2+ sensor to gate the channels. In heterologous expression systems, phosphatidylinositol 4,5-bisphosphate (PIP2) coordinates with CaM in regulating SK channels. However, the roles and mechanisms of PIP2 in regulating SK channels in cardiomyocytes remain unknown. Here, optogenetics, magnetic nanoparticles, combined with Rosetta structural modeling, and molecular dynamics (MD) simulations revealed the atomistic mechanisms of how PIP2 works in concert with Ca2+-CaM in the SK channel activation. Our computational study affords evidence for the critical role of the amino acid residue R395 in the S6 transmembrane segment, which is localized in propinquity to the intracellular hydrophobic gate. This residue forms a salt bridge with residue E398 in the S6 transmembrane segment from the adjacent subunit. Both R395 and E398 are conserved in all known isoforms of SK channels. Our findings suggest that the binding of PIP2 to R395 residue disrupts the R395:E398 salt bridge, increasing the flexibility of the transmembrane segment S6 and the activation of the channel. Importantly, our findings serve as a platform for testing of structural-based drug designs for therapeutic inhibitors and activators of the SK channel family. The study is timely since inhibitors of SK channels are currently in clinical trials to treat atrial arrhythmias.
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Grants
- NIH R01 HL085727 NIH R01 HL085844 NIH R01 HL137228 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH R01 HL158961 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH F32 HL151130 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH T32 HL86350 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH R01 HL128537 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH R01 HL152681 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- NIH R01 AG060504 and NIH 2P01 AG051443 HHS | NIH | National Institute on Aging (NIA)
- NIH R01 DC016099 HHS | NIH | National Institute on Deafness and Other Communication Disorders (NIDCD)
- NIH R35 GM149211 HHS | NIH | National Institute of General Medical Sciences (NIGMS)
- Anton 2 allocation MCB210014P Pittsburgh Supercomputing Center
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Affiliation(s)
- Ryan L Woltz
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Yang Zheng
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Woori Choi
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Khoa Ngo
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Pauline Trinh
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Lu Ren
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA 94305
| | - Phung N Thai
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Brandon J Harris
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Yanxiao Han
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Kyle C Rouen
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Diego Lopez Mateos
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Zhong Jian
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Eamonn J Dickson
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
| | - Ebenezer N Yamoah
- Department of Translational Neuroscience, University of Arizona College of Medicine, Phoenix, AZ 85004
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
- Department of Anesthesiology and Pain Medicine, University of California, Davis, CA 95616
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Xiao-Dong Zhang
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California, Davis, CA 95616
- Department of Pharmacology, University of California, Davis, CA 95616
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004
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2
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Chen Y, Bao L, Dong F, Xv M, Li W, Luo T, Xing C, Yan N, Niu K, Zhang N, Fan H. Effect of fibroblasts small- conductance Ca 2+ -activated potassium channel subtype 2 (SK2) on myocardial fibrosis in pressure overload mouse. Cell Signal 2024; 124:111401. [PMID: 39260533 DOI: 10.1016/j.cellsig.2024.111401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 08/30/2024] [Accepted: 09/06/2024] [Indexed: 09/13/2024]
Abstract
Studies have shown that Small conductance Ca2 + -activated K+ (SK) channel are expressed in fibroblasts. We aimed to determine the expression of SK2 channels in cardiac fibroblasts during myocardial hypertrophy and investigate its relationship with fibrotic remodeling. Myocardial hypertrophy and fibrotic remodeling induced by transverse aortic constriction (TAC) were assessed by echocardiography, Masson's trichrome staining and Western blot. Knockdown and overexpression of the SK2 protein were used to assess relationship between SK2 expression in fibroblasts and myocardial fibrosis. There is a positive correlation between myocardial fibrosis and SK2 channel protein expression during the development of myocardial hypertrophy. The differentiation and secretion of fibroblasts in mice with cardiac hypertrophy are enhanced, and the expression of SK2 channel protein is increased. Manipulating SK2 levels in fibroblasts can either promote or inhibit their differentiation and secretory function. Knocking down SK2 reduces the up-regulation of TGF β1, p-Smad2/3/GAPDH, p-p38/GAPDH, p-ERK1/2/GAPDH, and p-JNK/GAPDH proteins induced by Ang II in cardiac fibroblasts without significantly affecting total protein levels. AAV9-SK2-RNAi injection in mice improves cardiac function. Collectively, our study suggests that the expression of the SK2 channel is significantly increased in fibroblasts of mice with myocardial hypertrophy, potentially impacting myocardial fibrosis remodeling via the TGF-β signaling pathway.
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Affiliation(s)
- Yihan Chen
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Limeng Bao
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Fengjuan Dong
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Menru Xv
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Weidong Li
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Tianxia Luo
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Chenxv Xing
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Ningning Yan
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Kangli Niu
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Ningyuan Zhang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China
| | - Hongkun Fan
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, No.100 Kexuedadao Road, Zhengzhou 450000, China.
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3
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Basalamah F, Dilogo IH, Raharjo SB, Mansyur M, Siregar NC, Ibrahim N, Setianto BY, Yuniadi Y. TBX3 transfection and nodal signal pathway inhibition promote differentiation of adipose mesenchymal stem cell to cardiac pacemaker-like cells. Stem Cell Res Ther 2024; 15:148. [PMID: 38778426 PMCID: PMC11112768 DOI: 10.1186/s13287-024-03760-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Mesenchymal stem cells (MSCs) are known as one of the best candidate cells to produce cardiac pacemaker-like cells (CPLCs). Upregulation of TBX3 transcription factor and inhibition of the nodal signal pathway have a significant role in the formation of cardiac pacemaker cells such as sinoatrial and atrioventricular nodes, which initiate the heartbeat and control the rhythm of heart contractions. This study aimed to confirm the effects of transfection of TBX3 transcription factor and inhibition of the nodal signal pathway on differentiating adipose-derived MSCs (AD-MSCs) to CPLCs. AD-MSCs were characterized using flow cytometry and three-lineage differentiation staining. METHODS The transfection of TBX3 plasmid was carried out using lipofectamine, and inhibition of the nodal signal pathway was done using the small-molecule SB431542. The morphology of the cells was observed using a light microscope. Pacemaker-specific markers, including TBX3, Cx30, HCN4, HCN1, HCN3, and KCNN4, were evaluated using the qRT-PCR method. For protein level, TBX3 and Cx30 were evaluated using ELISA and immunofluorescence staining. The electrophysiology of cells was evaluated using a patch clamp. RESULTS The TBX3 expression in the TBX3, SM, and TBX + SM groups significantly higher (p < 0.05) compared to the control group and cardiomyocytes. The expression of Cx40 and Cx43 genes were lower in TBX3, SM, TBX + SM groups. In contrast, Cx30 gene showed higher expression in TBX3 group. The expression HCN1, HCN3, and HCN4 genes are higher in TBX3 group. CONCLUSION The transfection of TBX3 and inhibition of the nodal signal pathway by small-molecule SB431542 enhanced differentiation of AD-MSCs to CPLCs.
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Affiliation(s)
- Faris Basalamah
- Doctoral Program in Medical Science, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
- Faculty of Medicine and Health, University Muhammadiyah Jakarta, Banten, 15419, Indonesia
| | - Ismail Hadisoebroto Dilogo
- Department of Orthopedic and Traumatology, Faculty of Medicine, Universitas Indonesia-Dr Cipto Mangunkusumo National General Hospital, Jakarta, 10430, Indonesia
- Stem Cell and Tissue Engineering Research Cluster, Indonesia Medical Education and Research Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
- Stem Cell Medical Technology Integrated Service Unit, Dr Cipto Mangunkusumo National General Hospital, Jakarta, 10430, Indonesia
| | - Sunu Budhi Raharjo
- Department of Cardiology and Vascular Medicine, Faculty of Medicine, Universitas Indonesia-National Heart Center Harapan Kita, Jakarta, 10430, Indonesia
| | - Muchtaruddin Mansyur
- Department of Community Medicine, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
| | - Nuryati Chairani Siregar
- Department of Anatomical Pathology, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
| | - Nurhadi Ibrahim
- Department of Medical Physiology and Biophysics, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
- Neuroscience and Brain Development Research Cluster, Indonesian Medical Education and Researsch Institute, Faculty of Medicine, Universitas Indonesia, Jakarta, 10430, Indonesia
| | - Budi Yuli Setianto
- Department of Cardiology and Vascular Medicine, Faculty of Medicine, Health and Nursing, Universitas Gajah Mada, Yogyakarta, 55281, Indonesia
| | - Yoga Yuniadi
- Department of Cardiology and Vascular Medicine, Faculty of Medicine, Universitas Indonesia-National Heart Center Harapan Kita, Jakarta, 10430, Indonesia.
- Department of Cardiology and Vascular Medicine, Faculty of Medicine, Universitas Indonesia-RS Jantung Dan Pembuluh Darah Harapan Kita, Jakarta, 10420, Indonesia.
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4
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Tu Z, Yang J, Fan C. The role of different nutrients in the prevention and treatment of cardiovascular diseases. Front Immunol 2024; 15:1393378. [PMID: 38799425 PMCID: PMC11116626 DOI: 10.3389/fimmu.2024.1393378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024] Open
Abstract
Cardiovascular health is a hot topic around the world, and as the incidence of cardiovascular disease increases each year, people are increasingly focusing on the management of their heart health. Dietary and lifestyle changes as non-pharmacological treatments have been increasingly recognized as important in the prevention of cardiovascular disease and in reducing the risk of cardiovascular accidents. Awareness of different nutrients and their effects on cardiovascular health is important for establishing a good dietary pattern. This review summarizes the effects of the five major nutrients in the daily diet, namely carbohydrates, proteins, dietary fats, vitamins, and minerals, on cardiovascular health, and aims to provide a more comprehensive understanding of the effects of a healthy dietary pattern on cardiovascular health.
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Affiliation(s)
| | | | - Chengming Fan
- Department of Cardiovascular Surgery, the Second Xiangya Hospital, Central South University, Changsha, China
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Segura É, Zhao J, Broszczak M, Audet F, Sauvé R, Parent L. Investigating the Impact of Electrostatic Interactions on Calmodulin Binding and Ca 2+-Dependent Activation of the Calcium-Gated Potassium SK4 Channel. Int J Mol Sci 2024; 25:4255. [PMID: 38673845 PMCID: PMC11050286 DOI: 10.3390/ijms25084255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/03/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
Ca2+ binding to the ubiquitous Ca2+ sensing protein calmodulin (CaM) activates the intermediate conductance Ca2+-activated SK4 channel. Potential hydrophilic pockets for CaM binding have been identified at the intracellular HA and HB helices in the C-terminal of SK4 from the three published cryo-EM structures of SK4. Single charge reversal substitutions at either site, significantly weakened the pull-down of SK4 by CaM wild-type (CaM), and decreased the TRAM-34 sensitive outward K+ current densities in native HEK293T cells when compared with SK4 WT measured under the same conditions. Only the doubly substituted SK4 R352D/R355D (HB helix) obliterated the CaM-mediated pull-down and thwarted outward K+ currents. However, overexpression of CaM E84K/E87K, which had been predicted to face the arginine doublet, restored the CaM-mediated pull-down of SK4 R352D/R355D and normalized its whole-cell current density. Virtual analysis of the putative salt bridges supports a unique role for the positively charged arginine doublet at the HB helix into anchoring the interaction with the negatively charged CaM glutamate 84 and 87 CaM. Our findings underscore the unique contribution of electrostatic interactions in carrying CaM binding onto SK4 and support the role of the C-terminal HB helix to the Ca2+-dependent gating process.
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Affiliation(s)
- Émilie Segura
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Centre de Recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, QC H1T 1C8, Canada; (É.S.); (F.A.)
| | - Juan Zhao
- Centre de Recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, QC H1T 1C8, Canada; (J.Z.); (M.B.)
| | - Marlena Broszczak
- Centre de Recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, QC H1T 1C8, Canada; (J.Z.); (M.B.)
| | - Frédéric Audet
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Centre de Recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, QC H1T 1C8, Canada; (É.S.); (F.A.)
| | - Rémy Sauvé
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, 2900 Bd Édouard-Montpetit, Montréal, QC H3T 1J4, Canada;
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Centre de Recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, QC H1T 1C8, Canada; (É.S.); (F.A.)
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6
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Pironet A, Vandewiele F, Vennekens R. Exploring the role of TRPM4 in calcium-dependent triggered activity and cardiac arrhythmias. J Physiol 2024; 602:1605-1621. [PMID: 37128952 DOI: 10.1113/jp283831] [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: 01/26/2023] [Accepted: 04/28/2023] [Indexed: 05/03/2023] Open
Abstract
Cardiac arrhythmias pose a major threat to a patient's health, yet prove to be often difficult to predict, prevent and treat. A key mechanism in the occurrence of arrhythmias is disturbed Ca2+ homeostasis in cardiac muscle cells. As a Ca2+-activated non-selective cation channel, TRPM4 has been linked to Ca2+-induced arrhythmias, potentially contributing to translating an increase in intracellular Ca2+ concentration into membrane depolarisation and an increase in cellular excitability. Indeed, evidence from genetically modified mice, analysis of mutations in human patients and the identification of a TRPM4 blocking compound that can be applied in vivo further underscore this hypothesis. Here, we provide an overview of these data in the context of our current understanding of Ca2+-dependent arrhythmias.
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Affiliation(s)
- Andy Pironet
- Laboratory of Ion Channel Research, VIB Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Frone Vandewiele
- Laboratory of Ion Channel Research, VIB Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Rudi Vennekens
- Laboratory of Ion Channel Research, VIB Centre for Brain and Disease Research, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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7
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Wang J, Guo W, Wang Q, Yang Y, Sun X. Recent advances of myotubularin-related (MTMR) protein family in cardiovascular diseases. Front Cardiovasc Med 2024; 11:1364604. [PMID: 38529329 PMCID: PMC10961392 DOI: 10.3389/fcvm.2024.1364604] [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: 01/04/2024] [Accepted: 02/27/2024] [Indexed: 03/27/2024] Open
Abstract
Belonging to a lipid phosphatase family containing 16 members, myotubularin-related proteins (MTMRs) are widely expressed in a variety of tissues and organs. MTMRs preferentially hydrolyzes phosphatidylinositol 3-monophosphate and phosphatidylinositol (3,5) bis-phosphate to generate phosphatidylinositol and phosphatidylinositol 5-monophosphate, respectively. These phosphoinositides (PIPs) promote membrane degradation during autophagosome-lysosomal fusion and are also involved in various regulatory signal transduction. Based on the ability of modulating the levels of these PIPs, MTMRs exert physiological functions such as vesicle trafficking, cell proliferation, differentiation, necrosis, cytoskeleton, and cell migration. It has recently been found that MTMRs are also involved in the occurrence and development of several cardiovascular diseases, including cardiomyocyte hypertrophy, proliferation of vascular smooth muscle cell, LQT1, aortic aneurysm, etc. This review summarizes the functions of MTMRs and highlights their pathophysiological roles in cardiovascular diseases.
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Affiliation(s)
- Jia Wang
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, China
- College of Medicine, Southwest Jiaotong University, Chengdu, Sichuan, China
| | - Wei Guo
- Clinical Research Center, Stomatological Hospital of Chongqing Medical University, Chongqing, China
| | - Qiang Wang
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, China
- College of Medicine, Southwest Jiaotong University, Chengdu, Sichuan, China
| | - Yongjian Yang
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, China
| | - Xiongshan Sun
- Department of Cardiology, The General Hospital of Western Theater Command, Chengdu, Sichuan, China
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8
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Babini H, Jiménez-Sábado V, Stogova E, Arslanova A, Butt M, Dababneh S, Asghari P, Moore EDW, Claydon TW, Chiamvimonvat N, Hove-Madsen L, Tibbits GF. hiPSC-derived cardiomyocytes as a model to study the role of small-conductance Ca 2+-activated K + (SK) ion channel variants associated with atrial fibrillation. Front Cell Dev Biol 2024; 12:1298007. [PMID: 38304423 PMCID: PMC10830749 DOI: 10.3389/fcell.2024.1298007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/05/2024] [Indexed: 02/03/2024] Open
Abstract
Atrial fibrillation (AF), the most common arrhythmia, has been associated with different electrophysiological, molecular, and structural alterations in atrial cardiomyocytes. Therefore, more studies are required to elucidate the genetic and molecular basis of AF. Various genome-wide association studies (GWAS) have strongly associated different single nucleotide polymorphisms (SNPs) with AF. One of these GWAS identified the rs13376333 risk SNP as the most significant one from the 1q21 chromosomal region. The rs13376333 risk SNP is intronic to the KCNN3 gene that encodes for small conductance calcium-activated potassium channels type 3 (SK3). However, the functional electrophysiological effects of this variant are not known. SK channels represent a unique family of K+ channels, primarily regulated by cytosolic Ca2+ concentration, and different studies support their critical role in the regulation of atrial excitability and consequently in the development of arrhythmias like AF. Since different studies have shown that both upregulation and downregulation of SK3 channels can lead to arrhythmias by different mechanisms, an important goal is to elucidate whether the rs13376333 risk SNP is a gain-of-function (GoF) or a loss-of-function (LoF) variant. A better understanding of the functional consequences associated with these SNPs could influence clinical practice guidelines by improving genotype-based risk stratification and personalized treatment. Although research using native human atrial cardiomyocytes and animal models has provided useful insights, each model has its limitations. Therefore, there is a critical need to develop a human-derived model that represents human physiology more accurately than existing animal models. In this context, research with human induced pluripotent stem cells (hiPSC) and subsequent generation of cardiomyocytes derived from hiPSC (hiPSC-CMs) has revealed the underlying causes of various cardiovascular diseases and identified treatment opportunities that were not possible using in vitro or in vivo studies with animal models. Thus, the ability to generate atrial cardiomyocytes and atrial tissue derived from hiPSCs from human/patients with specific genetic diseases, incorporating novel genetic editing tools to generate isogenic controls and organelle-specific reporters, and 3D bioprinting of atrial tissue could be essential to study AF pathophysiological mechanisms. In this review, we will first give an overview of SK-channel function, its role in atrial fibrillation and outline pathophysiological mechanisms of KCNN3 risk SNPs. We will then highlight the advantages of using the hiPSC-CM model to investigate SNPs associated with AF, while addressing limitations and best practices for rigorous hiPSC studies.
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Affiliation(s)
- Hosna Babini
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Verónica Jiménez-Sábado
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- IIB SANT PAU, and CIBERCV, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Ekaterina Stogova
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Alia Arslanova
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Mariam Butt
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Saif Dababneh
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Parisa Asghari
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Edwin D. W. Moore
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Thomas W. Claydon
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | | | - Leif Hove-Madsen
- IIB SANT PAU, and CIBERCV, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain
| | - Glen F. Tibbits
- Cellular and Regenerative Medicine Centre, BC Children’s Hospital Research Institute, Vancouver, BC, Canada
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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9
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Giommi A, Gurgel ARB, Smith GL, Workman AJ. Does the small conductance Ca 2+-activated K + current I SK flow under physiological conditions in rabbit and human atrial isolated cardiomyocytes? J Mol Cell Cardiol 2023; 183:70-80. [PMID: 37704101 DOI: 10.1016/j.yjmcc.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/16/2023] [Accepted: 09/02/2023] [Indexed: 09/15/2023]
Abstract
BACKGROUND The small conductance Ca2+-activated K+ current (ISK) is a potential therapeutic target for treating atrial fibrillation. AIM To clarify, in rabbit and human atrial cardiomyocytes, the intracellular [Ca2+]-sensitivity of ISK, and its contribution to action potential (AP) repolarisation, under physiological conditions. METHODS Whole-cell-patch clamp, fluorescence microscopy: to record ion currents, APs and [Ca2+]i; 35-37°C. RESULTS In rabbit atrial myocytes, 0.5 mM Ba2+ (positive control) significantly decreased whole-cell current, from -12.8 to -4.9 pA/pF (P < 0.05, n = 17 cells, 8 rabbits). By contrast, the ISK blocker apamin (100 nM) had no effect on whole-cell current, at any set [Ca2+]i (∼100-450 nM). The ISK blocker ICAGEN (1 μM: ≥2 x IC50) also had no effect on current over this [Ca2+]i range. In human atrial myocytes, neither 1 μM ICAGEN (at [Ca2+]i ∼ 100-450 nM), nor 100 nM apamin ([Ca2+]i ∼ 250 nM) affected whole-cell current (5-10 cells, 3-5 patients/group). APs were significantly prolonged (at APD30 and APD70) by 2 mM 4-aminopyridine (positive control) in rabbit atrial myocytes, but 1 μM ICAGEN had no effect on APDs, versus either pre-ICAGEN or time-matched controls. High concentration (10 μM) ICAGEN (potentially ISK-non-selective) moderately increased APD70 and APD90, by 5 and 26 ms, respectively. In human atrial myocytes, 1 μM ICAGEN had no effect on APD30-90, whether stimulated at 1, 2 or 3 Hz (6-9 cells, 2-4 patients/rate). CONCLUSION ISK does not flow in human or rabbit atrial cardiomyocytes with [Ca2+]i set within the global average diastolic-systolic range, nor during APs stimulated at physiological or supra-physiological (≤3 Hz) rates.
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Affiliation(s)
- Alessandro Giommi
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Aline R B Gurgel
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Godfrey L Smith
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Antony J Workman
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK.
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10
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Herrera NT, Zhang X, Ni H, Maleckar MM, Heijman J, Dobrev D, Grandi E, Morotti S. Dual effects of the small-conductance Ca 2+-activated K + current on human atrial electrophysiology and Ca 2+-driven arrhythmogenesis: an in silico study. Am J Physiol Heart Circ Physiol 2023; 325:H896-H908. [PMID: 37624096 PMCID: PMC10659325 DOI: 10.1152/ajpheart.00362.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/11/2023] [Accepted: 08/11/2023] [Indexed: 08/26/2023]
Abstract
By sensing changes in intracellular Ca2+, small-conductance Ca2+-activated K+ (SK) channels dynamically regulate the dynamics of the cardiac action potential (AP) on a beat-to-beat basis. Given their predominance in atria versus ventricles, SK channels are considered a promising atrial-selective pharmacological target against atrial fibrillation (AF), the most common cardiac arrhythmia. However, the precise contribution of SK current (ISK) to atrial arrhythmogenesis is poorly understood, and may potentially involve different mechanisms that depend on species, heart rates, and degree of AF-induced atrial remodeling. Both reduced and enhanced ISK have been linked to AF. Similarly, both SK channel up- and downregulation have been reported in chronic AF (cAF) versus normal sinus rhythm (nSR) patient samples. Here, we use our multiscale modeling framework to obtain mechanistic insights into the contribution of ISK in human atrial cardiomyocyte electrophysiology. We simulate several protocols to quantify how ISK modulation affects the regulation of AP duration (APD), Ca2+ transient, refractoriness, and occurrence of alternans and delayed afterdepolarizations (DADs). Our simulations show that ISK activation shortens the APD and atrial effective refractory period, limits Ca2+ cycling, and slightly increases the propensity for alternans in both nSR and cAF conditions. We also show that increasing ISK counteracts DAD development by enhancing the repolarization force that opposes the Ca2+-dependent depolarization. Taken together, our results suggest that increasing ISK in human atrial cardiomyocytes could promote reentry while protecting against triggered activity. Depending on the leading arrhythmogenic mechanism, ISK inhibition may thus be a beneficial or detrimental anti-AF strategy.NEW & NOTEWORTHY Using our established framework for human atrial myocyte simulations, we investigated the role of the small-conductance Ca2+-activated K+ current (ISK) in the regulation of cell function and the development of Ca2+-driven arrhythmias. We found that ISK inhibition, a promising atrial-selective pharmacological strategy against atrial fibrillation, counteracts the reentry-promoting abbreviation of atrial refractoriness, but renders human atrial myocytes more vulnerable to delayed afterdepolarizations, thus potentially increasing the propensity for ectopic (triggered) activity.
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Affiliation(s)
- Nathaniel T Herrera
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Xianwei Zhang
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Mary M Maleckar
- Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway
| | - Jordi Heijman
- Department of Cardiology, Faculty of Health, Medicine, and Life Sciences, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Dobromir Dobrev
- Faculty of Medicine, West German Heart and Vascular Center, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas, United States
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, United States
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California, United States
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11
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Shi S, Mao X, Lv J, Wang Y, Zhang X, Shou X, Zhang B, Li Y, Wu H, Song Q, Hu Y. Qi-Po-Sheng-Mai granule ameliorates Ach-CaCl 2 -induced atrial fibrillation by regulating calcium homeostasis in cardiomyocytes. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 119:155017. [PMID: 37597360 DOI: 10.1016/j.phymed.2023.155017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/15/2023] [Accepted: 08/06/2023] [Indexed: 08/21/2023]
Abstract
BACKGROUND Atrial fibrillation (AF) is one of the most common arrhythmias encountered in clinical settings. Currently, the pathophysiology of AF remains unclear, which severely limits the effectiveness and safety of medical therapies. The Chinese herbal formula Qi-Po-Sheng-Mai Granule (QPSM) has been widely used in China to treat AF. However, its pharmacological and molecular mechanisms remain unknown. PURPOSE The purpose of this study was to investigate the molecular mechanisms and potential targets of QPSM for AF. STUDY DESIGN AND METHODS The AF model was induced by Ach (66 μg/ml) and CaCl2 (10 mg/kg), and the dose of 0.1 ml/100 g was injected into the tail vein for 5 weeks. QPSM was administered daily at doses of 4.42 and 8.84 g/kg, and amiodarone (0.18 g/kg) was used as the positive control. The effect of QPSM on AF was assessed by electrocardiogram, echocardiography, and histopathological analysis. Then, we employed network pharmacology with single nucleus RNA sequencing (snRNA-Seq) to investigate the molecular mechanisms and potential targets of QPSM for AF. Furthermore, high performance liquid chromatography (HPLC) method was used for component analysis of QPSM, and molecular docking was used to verify the potential targets. Using the IonOptix single cell contraction and ion synchronization test equipment, single myocyte length and calcium ion variations were observed in real time. The expression levels of calcium Transporter-related proteins were detected by western blot and immunohistochemistry. RESULTS Based on an Ach-CaCl2-induced AF model, we found that QPSM treatment significantly reduced atrial electrical remodeling-related markers, such as AF inducibility and duration, and attenuated atrial dilation and fibrosis. Network pharmacology identified 52 active ingredients and 119 potential targets for QPSM in the treatment of AF, and 45 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were enriched, among which calcium pathway had the greatest impact. Using single nucleus sequencing (snRNA-seq), we identified cardiomyocytes as the most differentially expressed in response to drug treatment, with nine differentially expressed genes enriched in calcium signaling pathways. High performance liquid chromatography and molecular docking confirmed that the core components of QPSM strongly bind to the key factors in the calcium signaling pathway. Additional experiments have shown that QPSM increases calcium transients (CaT) and contractility in the individual cardiomyocyte. This was accomplished by increasing the expression of CACNA1C and SERCA2a and decreasing the expression of CAMK2B and NCX1. CONCLUSION The present study has systematically elucidated the role of QPSM in maintaining calcium homeostasis in cardiomyocytes through the regulation of calcium transporters, which could lead to new drug development ideas for AF.
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Affiliation(s)
- Shuqing Shi
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Xinxin Mao
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Jiayu Lv
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Yajiao Wang
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Xuesong Zhang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xintian Shou
- China Academy of Chinese Medical Sciences, Beijing, China
| | - Bingxuan Zhang
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Yumeng Li
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China
| | - Huaqin Wu
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Qingqiao Song
- Department of Internal Medicine, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, 5 Beixiange Street Xicheng District, Beijing 100053, China.
| | - Yuanhui Hu
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
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12
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Zhong H, Ran X, Chen B, Xiong Y, Yu X. Apamin, an SK2 Inhibitor, Attenuated Neonatal Sevoflurane Exposures Caused Cognitive Deficits in Mice through the Regulation of Hippocampal Neuroinflammation. ACS Chem Neurosci 2023; 14:3409-3417. [PMID: 37647501 DOI: 10.1021/acschemneuro.3c00310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
Cognitive dysfunction induced by anesthesia in the infant is a crucial clinical issue that is still being debated and the focus of concern for the parents. However, the mechanism of cognitive decline caused by anesthesia and the corresponding treatment methods remain unclear. Postnatal day 7 (PND7) C57BL/6 mice included in the study were randomly divided into a control group (Control), a group with repeated exposure to sevoflurane (Sevo), and an Apamin intervention group (Sevo + Apamin). Apamin (0.5 μL at the concentration of 100 nmol/L) was injected into the bilateral hippocampus of mice. qRT-PCR, enzyme-linked immunosorbent assay (ELISA), and western blotting assay were used to evaluate the protein levels in the hippocampus. Object location memory (OLM) and novel object recognition (NOR) tasks, as well as elevated plus maze and contextual and cued fear conditioning tasks were used to evaluate the cognitive function of mice. Apamin mitigated sevoflurane-induced cognitive impairment of mice, sevoflurane-induced neuronal injury, and sevoflurane-induced activation of microglial in the hippocampus of the mice. Apamin inhibited M1-type polarization but promoted M2-type polarization of microglia after neonatal sevoflurane exposures in the hippocampus. In conclusion, Apamin attenuates neonatal sevoflurane exposures that cause cognitive deficits in mice through regulating hippocampal neuroinflammation.
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Affiliation(s)
- Heying Zhong
- Department of Anesthesiology, Affiliated Huadu Hospital, Southern Medical University (People's Hospital of Huadu District), Guangzhou 510000, Guangdong, China
| | - Xiaojuan Ran
- School of Basic Medicine, Guizhou University of Traditional Chinese Medicine, Guiyang 550003, Guizhou, China
| | - Bin Chen
- Department of Anesthesiology, Zunyi Medical University, Zunyi 563000, Guizhou, China
| | - Yiqiang Xiong
- Department of Anesthesiology, Zunyi Medical University, Zunyi 563000, Guizhou, China
| | - Xiangdi Yu
- Department of Anesthesiology, Guizhou Provincial People's Hospital, No. 83 Zhongshan Road, Nanming District, Guiyang 550003, Guizhou, China
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13
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Zhang XD, Chiamvimonvat N. Targeting Small-Conductance Calcium-Activated Potassium Channels in Atrial Fibrillation: Therapeutic Opportunities. Circ Res 2023; 132:1104-1106. [PMID: 37104564 PMCID: PMC10155264 DOI: 10.1161/circresaha.123.322777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine (X.-D.Z., N.C.), School of Medicine, University of California, Davis
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine (X.-D.Z., N.C.), School of Medicine, University of California, Davis
- Department of Pharmacology (N.C.), School of Medicine, University of California, Davis
- Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
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14
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Nam YW, Downey M, Rahman MA, Cui M, Zhang M. Channelopathy of small- and intermediate-conductance Ca 2+-activated K + channels. Acta Pharmacol Sin 2023; 44:259-267. [PMID: 35715699 PMCID: PMC9889811 DOI: 10.1038/s41401-022-00935-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 05/31/2022] [Indexed: 02/04/2023] Open
Abstract
Small- and intermediate-conductance Ca2+-activated K+ (KCa2.x/KCa3.1 also called SK/IK) channels are gated exclusively by intracellular Ca2+. The Ca2+ binding protein calmodulin confers sub-micromolar Ca2+ sensitivity to the channel-calmodulin complex. The calmodulin C-lobe is constitutively associated with the proximal C-terminus of the channel. Interactions between calmodulin N-lobe and the channel S4-S5 linker are Ca2+-dependent, which subsequently trigger conformational changes in the channel pore and open the gate. KCNN genes encode four subtypes, including KCNN1 for KCa2.1 (SK1), KCNN2 for KCa2.2 (SK2), KCNN3 for KCa2.3 (SK3), and KCNN4 for KCa3.1 (IK). The three KCa2.x channel subtypes are expressed in the central nervous system and the heart. The KCa3.1 subtype is expressed in the erythrocytes and the lymphocytes, among other peripheral tissues. The impact of dysfunctional KCa2.x/KCa3.1 channels on human health has not been well documented. Human loss-of-function KCa2.2 mutations have been linked with neurodevelopmental disorders. Human gain-of-function mutations that increase the apparent Ca2+ sensitivity of KCa2.3 and KCa3.1 channels have been associated with Zimmermann-Laband syndrome and hereditary xerocytosis, respectively. This review article discusses the physiological significance of KCa2.x/KCa3.1 channels, the pathophysiology of the diseases linked with KCa2.x/KCa3.1 mutations, the structure-function relationship of the mutant KCa2.x/KCa3.1 channels, and potential pharmacological therapeutics for the KCa2.x/KCa3.1 channelopathy.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Myles Downey
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA, 02115, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA.
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15
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Qi D, Li W, Quan XQ, Gao Y, Wang J, Guo L, Zhao W, Liu T, Gao C, Yan GX. Alternating Early Afterdepolarizations Underlying Bradycardia-Dependent Macroscopic T Wave and Discordant Mechanical Alternans. Circ Arrhythm Electrophysiol 2023; 16:e011453. [PMID: 36595630 DOI: 10.1161/circep.122.011453] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Macroscopic T wave alternans (macro-TWA) often heralds the onset of Torsades de Pointes in patients with QT prolongation. However, the mechanisms underlying macro-TWA remain unclear. We examined the cellular and ionic basis for macro-TWA in rabbits with left ventricular hypertrophy (LVH). METHODS The renovascular hypertension model was used to induce LVH in rabbits. Action potentials were simultaneously recorded from epicardium and endocardium together with a transmural ECG and isometric contractility in arterially perfused left ventricular wedges. Late sodium current (INa-L) was recorded in single-isolated left ventricular myocytes with the whole cell patch-clamp technique. RESULTS Macro-TWA and accompanied mechanical alternans occurred spontaneously in 8 of 33 LVH rabbits (P<0.05, versus 0/15 in controls) and were induced by an INa-L enhancer ATX-II at 1 to 3 nM in additional 7. Macro-TWA and mechanical alternans occurred discordantly, that is, that longer QT interval and larger T wave were associated with weaker isometric contvractility. Alternating early afterdepolarizations in the endocardium caused macro-TWA in 12 of 15 LVH rabbits and, therefore, early afterdepolarization-dependent R-from-T extrasystoles and Torsades de Pointes always originated from the beats with longer QT and larger T wave during macro-TWA. INa-L density was significantly larger in LVH myocytes than that of control myocytes. Macro-TWA, mechanical alternans, R-from-T extrasystoles, and Torsades de Pointes were all abolished by INa-L blocker ranolazine or mexiletine. CONCLUSIONS LVH enhances INa-L density and promotes alternating early afterdepolarizations in the left ventricular endocardium that manifest as macro-TWA with discordant mechanical alternans. INa-L blockade abolishes macro-TWA, mechanical alternans, early afterdepolarization-dependent R-from-T extrasystoles, and Torsades de Pointes.
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Affiliation(s)
- Datun Qi
- Zhengzhou University People's Hospital and Central China Fuwai Hospital, Zhengzhou, China (D.Q., C.G., G.-X.Y.).,Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.)
| | - Wei Li
- Department of Cardiology, Xinhua Hospital, Shanghai, China (W.L.)
| | - Xiao-Qing Quan
- Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.)
| | - Yuan Gao
- Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.).,Henan University of Traditional Chinese Medicine, Zhengzhou, China (Y.G.)
| | - Jianyong Wang
- Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.).,TEDA International Cardiovascular Hospital, Tianjin, China (J.W.)
| | | | - Wenping Zhao
- Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.).,Affiliated Hospital of Hebei University, Baoding, China (W.Z.)
| | - Tong Liu
- Department of Cardiology, Second Hospital of Tianjin Medical University, China (T.L.)
| | - Chuanyu Gao
- Zhengzhou University People's Hospital and Central China Fuwai Hospital, Zhengzhou, China (D.Q., C.G., G.-X.Y.)
| | - Gan-Xin Yan
- Zhengzhou University People's Hospital and Central China Fuwai Hospital, Zhengzhou, China (D.Q., C.G., G.-X.Y.).,Lankenau Institute for Medical Research, Wynnewood, PA (D.Q., X.-Q.Q., Y.G., J.W., W.Z., G.-X.Y.).,Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA (G.-X.Y.)
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16
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Kanaporis G, Blatter LA. Activation of small conductance Ca 2+ -activated K + channels suppresses Ca 2+ transient and action potential alternans in ventricular myocytes. J Physiol 2023; 601:51-67. [PMID: 36426548 PMCID: PMC9878619 DOI: 10.1113/jp283870] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022] Open
Abstract
At the cellular level, cardiac alternans is observed as beat-to-beat alternations in contraction strength, action potential (AP) morphology and Ca2+ transient (CaT) amplitude, and is a risk factor for cardiac arrhythmia. The (patho)physiological roles of small conductance Ca2+ -activated K+ (SK) channels in ventricles are poorly understood. We tested the hypothesis that in single rabbit ventricular myocytes pharmacological modulation of SK channels plays a causative role for the development of pacing-induced CaT and AP duration (APD) alternans. SK channel blockers (apamin, UCL1684) had only a minor effect on AP repolarization. However, SK channel activation by NS309 resulted in significant APD shortening, demonstrating that functional SK channels are well expressed in ventricular myocytes. The effects of NS309 were prevented or reversed by apamin and UCL1684, indicating that NS309 acted on SK channels. SK channel activation abolished or reduced the degree of pacing-induced CaT and APD alternans. Inhibition of KV 7.1 (with HMR1556) and KV 11.1 (with E4031) channels was used to mimic conditions of long QT syndromes type-1 and type-2, respectively. Both HMR1556 and E4031 enhanced CaT alternans that was prevented by SK channel activation. In AP voltage-clamped cells the SK channel activator had no effect on CaT alternans, confirming that suppression of CaT alternans was caused by APD shortening. APD shortening contributed to protection from alternans by lowering sarcoplasmic reticulum Ca2+ content and curtailing Ca2+ release. The data suggest that SK activation could be a potential intervention to avert development of alternans with important ramifications for arrhythmia prevention and therapy for patients with long QT syndrome. KEY POINTS: At the cellular level, cardiac alternans is observed as beat-to-beat alternations in contraction strength, action potential (AP) morphology and intracellular Ca2+ release amplitude, and is a risk factor for cardiac arrhythmia. The (patho)physiological roles of small conductance Ca2+ -activated K+ (SK) channels in ventricles are poorly understood. We investigated whether pharmacological modulation of SK channels affects the development of cardiac alternans in normal ventricular cells and in cells with drug-induced long QT syndrome (LQTS). While SK channel blockers have only a minor effect on AP morphology, their activation leads to AP shortening and abolishes or reduces the degree of pacing-induced Ca2+ and AP alternans. AP shortening contributed to protection against alternans by lowering sarcoplasmic reticulum Ca2+ content and curtailing Ca2+ release. The data suggest SK activation as a potential intervention to avert the development of alternans with important ramifications for arrhythmia prevention for patients with LQTS.
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Affiliation(s)
- Giedrius Kanaporis
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois, USA
| | - Lothar A Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois, USA
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17
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Heijman J, Dobrev D. Molecular determinants and therapeutic potential of focal ectopic activity: more than meets the Iti. Eur Heart J 2022; 43:4208-4210. [PMID: 35822877 DOI: 10.1093/eurheartj/ehac357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University of Duisburg-Essen, Essen, Germany.,Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA.,Departments of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montréal, Canada
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18
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Sirish P, Diloretto DA, Thai PN, Chiamvimonvat N. The Critical Roles of Proteostasis and Endoplasmic Reticulum Stress in Atrial Fibrillation. Front Physiol 2022; 12:793171. [PMID: 35058801 PMCID: PMC8764384 DOI: 10.3389/fphys.2021.793171] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/08/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) remains the most common arrhythmia seen clinically. The incidence of AF is increasing due to the aging population. AF is associated with a significant increase in morbidity and mortality, yet current treatment paradigms have proven largely inadequate. Therefore, there is an urgent need to develop new effective therapeutic strategies for AF. The endoplasmic reticulum (ER) in the heart plays critical roles in the regulation of excitation-contraction coupling and cardiac function. Perturbation in the ER homeostasis due to intrinsic and extrinsic factors, such as inflammation, oxidative stress, and ischemia, leads to ER stress that has been linked to multiple conditions including diabetes mellitus, neurodegeneration, cancer, heart disease, and cardiac arrhythmias. Recent studies have documented the critical roles of ER stress in the pathophysiological basis of AF. Using an animal model of chronic pressure overload, we demonstrate a significant increase in ER stress in atrial tissues. Moreover, we demonstrate that treatment with a small molecule inhibitor to inhibit the soluble epoxide hydrolase enzyme in the arachidonic acid metabolism significantly reduces ER stress as well as atrial electrical and structural remodeling. The current review article will attempt to provide a perspective on our recent understandings and current knowledge gaps on the critical roles of proteostasis and ER stress in AF progression.
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Affiliation(s)
- Padmini Sirish
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, United States.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, United States
| | - Daphne A Diloretto
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, United States
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, United States.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, United States
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, United States.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, United States.,Department of Pharmacology, University of California, Davis, Davis, CA, United States
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Stretching the limits of antiarrhythmic drug therapy: The promise of small-conductance calcium-activated potassium channel blockers. IJC HEART & VASCULATURE 2021; 37:100924. [PMID: 34917752 PMCID: PMC8645440 DOI: 10.1016/j.ijcha.2021.100924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 11/24/2021] [Indexed: 11/19/2022]
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Kulawiak B, Bednarczyk P, Szewczyk A. Multidimensional Regulation of Cardiac Mitochondrial Potassium Channels. Cells 2021; 10:1554. [PMID: 34205420 PMCID: PMC8235349 DOI: 10.3390/cells10061554] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondria play a fundamental role in the energetics of cardiac cells. Moreover, mitochondria are involved in cardiac ischemia/reperfusion injury by opening the mitochondrial permeability transition pore which is the major cause of cell death. The preservation of mitochondrial function is an essential component of the cardioprotective mechanism. The involvement of mitochondrial K+ transport in this complex phenomenon seems to be well established. Several mitochondrial K+ channels in the inner mitochondrial membrane, such as ATP-sensitive, voltage-regulated, calcium-activated and Na+-activated channels, have been discovered. This obliges us to ask the following question: why is the simple potassium ion influx process carried out by several different mitochondrial potassium channels? In this review, we summarize the current knowledge of both the properties of mitochondrial potassium channels in cardiac mitochondria and the current understanding of their multidimensional functional role. We also critically summarize the pharmacological modulation of these proteins within the context of cardiac ischemia/reperfusion injury and cardioprotection.
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Affiliation(s)
- Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland;
| | - Piotr Bednarczyk
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland;
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland;
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Bare DJ, Yue L, Ai X. A special issue on calcium dynamics of the heart: remodeling of ion channels and regulatory pathways. Pflugers Arch 2021; 473:313-316. [PMID: 33666746 PMCID: PMC7940331 DOI: 10.1007/s00424-021-02532-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 01/27/2021] [Accepted: 02/01/2021] [Indexed: 11/24/2022]
Affiliation(s)
- Dan J Bare
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, 60612, USA
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut Health Center, Farmington, CT, 06030, USA.
| | - Xun Ai
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL, 60612, USA.
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