51
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Leipold E. Mechanosensitivity of Na V1.5 sodium channels is regulated by specific β-subunits. Pflugers Arch 2019; 471:1381-1382. [PMID: 31748932 DOI: 10.1007/s00424-019-02333-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/14/2019] [Accepted: 11/14/2019] [Indexed: 10/25/2022]
Affiliation(s)
- Enrico Leipold
- Department of Anesthesiology and Intensive Care, University of Luebeck, Luebeck, Germany.
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52
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Cortada E, Brugada R, Verges M. Trafficking and Function of the Voltage-Gated Sodium Channel β2 Subunit. Biomolecules 2019; 9:biom9100604. [PMID: 31614896 PMCID: PMC6843408 DOI: 10.3390/biom9100604] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 12/15/2022] Open
Abstract
The voltage-gated sodium channel is vital for cardiomyocyte function, and consists of a protein complex containing a pore-forming α subunit and two associated β subunits. A fundamental, yet unsolved, question is to define the precise function of β subunits. While their location in vivo remains unclear, large evidence shows that they regulate localization of α and the biophysical properties of the channel. The current data support that one of these subunits, β2, promotes cell surface expression of α. The main α isoform in an adult heart is NaV1.5, and mutations in SCN5A, the gene encoding NaV1.5, often lead to hereditary arrhythmias and sudden death. The association of β2 with cardiac arrhythmias has also been described, which could be due to alterations in trafficking, anchoring, and localization of NaV1.5 at the cardiomyocyte surface. Here, we will discuss research dealing with mechanisms that regulate β2 trafficking, and how β2 could be pivotal for the correct localization of NaV1.5, which influences cellular excitability and electrical coupling of the heart. Moreover, β2 may have yet to be discovered roles on cell adhesion and signaling, implying that diverse defects leading to human disease may arise due to β2 mutations.
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Affiliation(s)
- Eric Cortada
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
| | - Ramon Brugada
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
- Medical Sciences Department, University of Girona Medical School, 17003 Girona, Spain.
- Cardiology Department, Hospital Josep Trueta, 17007 Girona, Spain.
| | - Marcel Verges
- Cardiovascular Genetics Group, Girona Biomedical Research Institute (IDIBGI), C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Girona, Spain.
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), 28029 Madrid, Spain.
- Medical Sciences Department, University of Girona Medical School, 17003 Girona, Spain.
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53
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Zhao L, Sun L, Lu Y, Li F, Xu H. A small-molecule LF3 abrogates β-catenin/TCF4-mediated suppression of Na V1.5 expression in HL-1 cardiomyocytes. J Mol Cell Cardiol 2019; 135:90-96. [PMID: 31419437 PMCID: PMC7088444 DOI: 10.1016/j.yjmcc.2019.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/06/2019] [Accepted: 08/13/2019] [Indexed: 12/18/2022]
Abstract
Increased nuclear β-catenin interacting with T-cell factor 4 (TCF4) affects the expression of target genes including SCN5A in ischemic heart disease, which is characterized by frequent ventricular tachycardia/fibrillation. A complex of β-catenin and TCF4 inhibits cardiac Na+ channel activity by reducing NaV1.5 expression through suppressing SCN5A promoter activity in HL-1 cardiomyocytes. LF3, a 4-thioureido-benzenesulfonamide derivative and an inhibitor of β-catenin/TCF4 interaction, has been shown to block the self-renewal capacity of cancer stem cells. We performed studies to determine if LF3 can reverse suppressive effects of β-catenin/TCF4 signaling on the expression of NaV1.5 in HL-1 cardiomyocytes. Western blotting and real-time qRT-PCR analyses showed that 10 μM LF3 significantly increased the expression of NaV1.5 but it did not alter β-catenin and TCF4 expression. Subcellular fractionation analysis demonstrated that LF3 significantly increased the levels of NaV1.5 in both membrane and cytoplasm. Whole-cell patch-clamp recordings revealed that Na+ currents were significantly increased with no changes in the steady-state parameters, activation and inactivation time constants and recovery from inactivation of Na+ channel in HL-1 cells treated with LF3. Immunoprecipitation exhibited that LF3 blocked the interaction of β-catenin and TCF4. Luciferase reporter assays performed in HEK 293 cells and HL-1 revealed that LF3 increased the SCN5A promoter activity in HL-1 cells and prevented β-catenin suppressive effect on SCN5A promoter activity in HEK 293 cells. Taken together, we conclude that LF3, an inhibitor of β-catenin/TCF4 interaction, elevates NaV1.5 expression, leading to increase Na+ channel activity in HL-1 cardiomyocytes.
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Affiliation(s)
- Limei Zhao
- Department of Pathology, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 90105, United States of America
| | - Lihua Sun
- Department of Pathology, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 90105, United States of America
| | - Yan Lu
- Department of Pathology, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 90105, United States of America
| | - Faqian Li
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, United States of America
| | - Haodong Xu
- Department of Pathology, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 90105, United States of America.
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54
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Cortada E, Brugada R, Verges M. N-Glycosylation of the voltage-gated sodium channel β2 subunit is required for efficient trafficking of Na V1.5/β2 to the plasma membrane. J Biol Chem 2019; 294:16123-16140. [PMID: 31511323 DOI: 10.1074/jbc.ra119.007903] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 09/01/2019] [Indexed: 01/25/2023] Open
Abstract
The voltage-gated sodium channel is critical for cardiomyocyte function and consists of a protein complex comprising a pore-forming α subunit and two associated β subunits. It has been shown previously that the associated β2 subunits promote cell surface expression of the α subunit. The major α isoform in the adult human heart is NaV1.5, and germline mutations in the NaV1.5-encoding gene, sodium voltage-gated channel α subunit 5 (SCN5A), often cause inherited arrhythmias. Here, we investigated the mechanisms that regulate β2 trafficking and how they may determine proper NaV1.5 cell surface localization. Using heterologous expression in polarized Madin-Darby canine kidney cells, we show that β2 is N-glycosylated in vivo and in vitro at residues 42, 66, and 74, becoming sialylated only at Asn-42. We found that fully nonglycosylated β2 was mostly retained in the endoplasmic reticulum, indicating that N-linked glycosylation is required for efficient β2 trafficking to the apical plasma membrane. The nonglycosylated variant reached the cell surface by bypassing the Golgi compartment at a rate of only approximately one-third of that of WT β2. YFP-tagged, nonglycosylated β2 displayed mobility kinetics in the plane of the membrane similar to that of WT β2. However, it was defective in promoting surface localization of NaV1.5. Interestingly, β2 with a single intact glycosylation site was as effective as the WT in promoting NaV1.5 surface localization. In conclusion, our results indicate that N-linked glycosylation of β2 is required for surface localization of NaV1.5, a property that is often defective in inherited cardiac arrhythmias.
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Affiliation(s)
- Eric Cortada
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain
| | - Ramon Brugada
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Medical Sciences Department, University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Cardiology Department, Hospital Josep Trueta, University of Girona Medical School, C/ Doctor Castany, s/nγÇôEdifici IDIBGI, 17190 SaltγÇôProv. Girona, Spain
| | - Marcel Verges
- Cardiovascular Genetics Group-Girona Biomedical Research Institute (IDIBGI), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain .,Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV), University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain.,Medical Sciences Department, University of Girona Medical School, C/ Doctor Castany, s/n-Edifici IDIBGI, 17190 Salt-Prov. Girona, Spain
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55
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Strober BJ, Elorbany R, Rhodes K, Krishnan N, Tayeb K, Battle A, Gilad Y. Dynamic genetic regulation of gene expression during cellular differentiation. Science 2019; 364:1287-1290. [PMID: 31249060 PMCID: PMC6623972 DOI: 10.1126/science.aaw0040] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 06/04/2019] [Indexed: 12/12/2022]
Abstract
Genetic regulation of gene expression is dynamic, as transcription can change during cell differentiation and across cell types. We mapped expression quantitative trait loci (eQTLs) throughout differentiation to elucidate the dynamics of genetic effects on cell type-specific gene expression. We generated time-series RNA sequencing data, capturing 16 time points during the differentiation of induced pluripotent stem cells to cardiomyocytes, in 19 human cell lines. We identified hundreds of dynamic eQTLs that change over time, with enrichment in enhancers of relevant cell types. We also found nonlinear dynamic eQTLs, which affect only intermediate stages of differentiation and cannot be found by using data from mature tissues. These fleeting genetic associations with gene regulation may explain some of the components of complex traits and disease. We highlight one example of a nonlinear eQTL that is associated with body mass index.
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Affiliation(s)
- B J Strober
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - R Elorbany
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL 60637, USA
- Interdisciplinary Scientist Training Program, University of Chicago, Chicago, IL 60637, USA
| | - K Rhodes
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - N Krishnan
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - K Tayeb
- Department of Applied Mathematics and Statistics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - A Battle
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Y Gilad
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA
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56
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Pethő Z, Najder K, Bulk E, Schwab A. Mechanosensitive ion channels push cancer progression. Cell Calcium 2019; 80:79-90. [PMID: 30991298 DOI: 10.1016/j.ceca.2019.03.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 03/26/2019] [Accepted: 03/26/2019] [Indexed: 02/07/2023]
Abstract
In many cases, the mechanical properties of a tumor are different from those of the host tissue. Mechanical cues regulate cancer development by affecting both tumor cells and their microenvironment, by altering cell migration, proliferation, extracellular matrix remodeling and metastatic spread. Cancer cells sense mechanical stimuli such as tissue stiffness, shear stress, tissue pressure of the extracellular space (outside-in mechanosensation). These mechanical cues are transduced into a cellular response (e. g. cell migration and proliferation; inside-in mechanotransduction) or to a response affecting the microenvironment (e. g. inducing a fibrosis or building up growth-induced pressure; inside-out mechanotransduction). These processes heavily rely on mechanosensitive membrane proteins, prominently ion channels. Mechanosensitive ion channels are involved in the Ca2+-signaling of the tumor and stroma cells, both directly, by mediating Ca2+ influx (e. g. Piezo and TRP channels), or indirectly, by maintaining the electrochemical gradient necessary for Ca2+ influx (e. g. K2P, KCa channels). This review aims to discuss the diverse roles of mechanosenstive ion channels in cancer progression, especially those involved in Ca2+-signaling, by pinpointing their functional relevance in tumor pathophysiology.
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Affiliation(s)
- Zoltán Pethő
- Institut für Physiologie II, Robert-Koch-Str. 27b, 48149 Münster, Germany.
| | - Karolina Najder
- Institut für Physiologie II, Robert-Koch-Str. 27b, 48149 Münster, Germany
| | - Etmar Bulk
- Institut für Physiologie II, Robert-Koch-Str. 27b, 48149 Münster, Germany
| | - Albrecht Schwab
- Institut für Physiologie II, Robert-Koch-Str. 27b, 48149 Münster, Germany
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57
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Iqbal SM, Lemmens‐Gruber R. Phosphorylation of cardiac voltage-gated sodium channel: Potential players with multiple dimensions. Acta Physiol (Oxf) 2019; 225:e13210. [PMID: 30362642 PMCID: PMC6590314 DOI: 10.1111/apha.13210] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 10/14/2018] [Accepted: 10/14/2018] [Indexed: 12/11/2022]
Abstract
Cardiomyocytes are highly coordinated cells with multiple proteins organized in micro domains. Minor changes or interference in subcellular proteins can cause major disturbances in physiology. The cardiac sodium channel (NaV1.5) is an important determinant of correct electrical activity in cardiomyocytes which are localized at intercalated discs, T‐tubules and lateral membranes in the form of a macromolecular complex with multiple interacting protein partners. The channel is tightly regulated by post‐translational modifications for smooth conduction and propagation of action potentials. Among regulatory mechanisms, phosphorylation is an enzymatic and reversible process which modulates NaV1.5 channel function by attaching phosphate groups to serine, threonine or tyrosine residues. Phosphorylation of NaV1.5 is implicated in both normal physiological and pathological processes and is carried out by multiple kinases. In this review, we discuss and summarize recent literature about the (a) structure of NaV1.5 channel, (b) formation and subcellular localization of NaV1.5 channel macromolecular complex, (c) post‐translational phosphorylation and regulation of NaV1.5 channel, and (d) how these phosphorylation events of NaV1.5 channel alter the biophysical properties and affect the channel during disease status. We expect, by reviewing these aspects will greatly improve our understanding of NaV1.5 channel biology, physiology and pathology, which will also provide an insight into the mechanism of arrythmogenesis at molecular level.
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Affiliation(s)
- Shahid M. Iqbal
- Department of Pharmacology and Toxicology University of Vienna Vienna Austria
- Drugs Regulatory Authority of Pakistan Telecom Foundation (TF) Complex Islamabad Pakistan
| | - Rosa Lemmens‐Gruber
- Department of Pharmacology and Toxicology University of Vienna Vienna Austria
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58
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UBC9 regulates cardiac sodium channel Na v1.5 ubiquitination, degradation and sodium current density. J Mol Cell Cardiol 2019; 129:79-91. [PMID: 30772377 DOI: 10.1016/j.yjmcc.2019.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 12/29/2022]
Abstract
Voltage-gated sodium channel Nav1.5 is critical for generation and conduction of cardiac action potentials. Mutations and expression level changes of Nav1.5 are associated with cardiac arrhythmias and sudden death. The ubiquitin (Ub) conjugation machinery utilizes three enzyme activities, E1, E2, and E3, to regulate protein degradation. Previous studies from us and others showed that Nedd4-2 acts as an E3 ubiquitin-protein ligase involved in ubiquitination and degradation of Nav1.5, however, more key regulators remain to be identified. In this study, we show that UBC9, a SUMO-conjugating enzyme, regulates ubiquitination and degradation of Nav1.5. Overexpression of UBC9 significantly decreased Nav1.5 expression and reduced sodium current densities, whereas knockdown of UBC9 expression significantly enhanced Nav1.5 expression and increased sodium current densities, in both HEK293 cells and primary neonatal cardiomyocytes. Overexpression of UBC9 increased ubiquitination of Nav1.5, and proteasome inhibitor MG132 blocked the effect of UBC9 overexpression on Nav1.5 degradation. Co-immunoprecipitation showed that UBC9 interacts with Nedd4-2. UBC9 with mutation C93S, which suppresses SUMO-conjugating activity of UBC9, was as active as wild type UBC9 in regulating Nav1.5 levels, suggesting that UBC9 regulates Nav1.5 expression levels in a SUMOylation-independent manner. Our findings thus identify a key structural element of the ubiquitin-conjugation machinery for Nav1.5 and provide important insights into the regulatory mechanism for ubiquitination and turnover of Nav1.5.
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59
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Guan Y, Gao X, Tang Q, Huang L, Gao S, Yu S, Huang J, Li J, Zhou D, Zhang Y, Shi D, Liang D, Liu Y, Li L, Cui Y, Xu L, Chen YH. Nucleoporin 107 facilitates the nuclear export of Scn5a mRNA to regulate cardiac bioelectricity. J Cell Mol Med 2018; 23:1448-1457. [PMID: 30506890 PMCID: PMC6349201 DOI: 10.1111/jcmm.14051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 10/13/2018] [Accepted: 11/05/2018] [Indexed: 01/02/2023] Open
Abstract
Nucleoporins (Nups) are known to be functional in nucleo‐cytoplasmic transport, but the roles of nucleoporins in nonproliferating cells, such as cardiac myocytes, are still poorly understood. In this study, we report that Nup107 regulates cardiac bioelectricity by controlling the nucleo‐cytoplasmic trafficking of Scn5a mRNA. Overexpression of Nup107 induced the protein expression of Scn5a rather than that of other ion channels, with no effects of their mRNA levels. The analysis for the protein production demonstrated Nup107‐facilitated transport of Scn5a mRNA. Using RIP‐PCR and luciferase assay, we found that the 5′‐UTR of Scn5a mRNA was not involved in the interaction, whereas the spatial interaction between Nup107 protein and Scn5a mRNA was formed when Scn5a mRNA passing through the nuclear pore. Functionally, Nup107 overexpression in neonatal rat ventricle myocytes significantly increased the currents of Scn5a‐encoded INa channel. Moreover, the close correlation between Nup107 and Nav1.5 protein expression was observed in cardiomycytes and heart tissues subjected to hypoxia and ischaemic insults, suggesting a fast regulation of Nup107 on Nav1.5 channel in cardiac myocytes in a posttranscriptional manner. These findings may provide insights into the emergent control of cardiac electrophysiology through Nup‐mediated modulation of ion channels.
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Affiliation(s)
- Yi Guan
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Xueting Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Qiuyu Tang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Lin Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Siyun Gao
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Shuai Yu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jiale Huang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jun Li
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Daizhan Zhou
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yangyang Zhang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dan Shi
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Dandan Liang
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Liu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Li Li
- Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Yingyu Cui
- Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Liang Xu
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi-Han Chen
- Heart Health Center, East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
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60
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Abstract
Activation of the electrical signal and its transmission as a depolarizing wave in the whole heart requires highly organized myocyte architecture and cell-cell contacts. In addition, complex trafficking and anchoring intracellular machineries regulate the proper surface expression of channels and their targeting to distinct membrane domains. An increasing list of proteins, lipids, and second messengers can contribute to the normal targeting of ion channels in cardiac myocytes. However, their precise roles in the electrophysiology of the heart are far from been extensively understood. Nowadays, much effort in the field focuses on understanding the mechanisms that regulate ion channel targeting to sarcolemma microdomains and their organization into macromolecular complexes. The purpose of the present section is to provide an overview of the characterized partners of the main cardiac sodium channel, NaV1.5, involved in regulating the functional expression of this channel both in terms of trafficking and targeting into microdomains.
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61
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Neubauer J, Rougier JS, Abriel H, Haas C. Functional implications of a rare variant in the sodium channel β1B subunit ( SCN1B) in a 5-month-old male sudden infant death syndrome case. HeartRhythm Case Rep 2018; 4:187-190. [PMID: 29915715 PMCID: PMC6003537 DOI: 10.1016/j.hrcr.2018.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Jacqueline Neubauer
- Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | | | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Cordula Haas
- Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
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62
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Manring HR, Dorn LE, Ex-Willey A, Accornero F, Ackermann MA. At the heart of inter- and intracellular signaling: the intercalated disc. Biophys Rev 2018; 10:961-971. [PMID: 29876873 DOI: 10.1007/s12551-018-0430-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 05/22/2018] [Indexed: 12/17/2022] Open
Abstract
Proper cardiac function requires the synchronous mechanical and electrical coupling of individual cardiomyocytes. The intercalated disc (ID) mediates coupling of neighboring myocytes through intercellular signaling. Intercellular communication is highly regulated via intracellular signaling, and signaling pathways originating from the ID control cardiomyocyte remodeling and function. Herein, we present an overview of the inter- and intracellular signaling that occurs at and originates from the intercalated disc in normal physiology and pathophysiology. This review highlights the importance of the intercalated disc as an integrator of signaling events regulating homeostasis and stress responses in the heart and the center of several pathophysiological processes mediating the development of cardiomyopathies.
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Affiliation(s)
- Heather R Manring
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Lisa E Dorn
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Aidan Ex-Willey
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Federica Accornero
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA.
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63
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Iqbal SM, Aufy M, Shabbir W, Lemmens-Gruber R. Identification of phosphorylation sites and binding pockets for modulation of Na V 1.5 channel by Fyn tyrosine kinase. FEBS J 2018; 285:2520-2530. [PMID: 29734505 DOI: 10.1111/febs.14496] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/05/2018] [Accepted: 04/30/2018] [Indexed: 11/26/2022]
Abstract
Cardiac sodium channel NaV 1.5 is the predominant form of sodium channels in cardiomyocytes, which exists as a macromolecular complex and interacts with multiple protein partners. Fyn kinase is one of the interacting proteins which colocalize, phosphorylate and modulate the NaV 1.5 channel. To elaborate this interaction we created expression vectors for the N-terminal, intracellular loop, and C-terminal regions of the NaV 1.5 channel, to express in HEK-293 cells. By co-immunoprecipitation and anti-phosphotyrosine blotting, we identified proline-rich binding sites for Fyn kinase in the N-terminal, IC-loopi-ii and C-terminal. After binding, Fyn kinase phosphorylates tyrosine residues present in the N- and C-terminal, which produce a depolarizing shift of 7 mV in fast inactivation. The functional relevance of these binding and phosphorylation sites was further underpinned by creating full length mutants masking these sites sequentially. An activation and inactivation curves were recorded with or without co-expressed Fyn kinase which indicates that phosphorylation of tyrosine residues at positions 68, 87, 112 in the N-terminal and at positions 1811 and 1889 in the C-terminal creates a depolarizing shift in fast inactivation of NaV 1.5 channel.
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Affiliation(s)
- Shahid Muhammad Iqbal
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria.,Drugs Regulatory Authority of Pakistan, Islamabad, Pakistan
| | - Mohammed Aufy
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Waheed Shabbir
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Rosa Lemmens-Gruber
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
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Abstract
INTRODUCTION AND OBJECTIVES The importance of sodium channels for the normal electrical activity of the heart is emphasized by the fact that mutations (inherited or de novo) in genes that encode for these channels or their associated proteins cause arrhythmogenic syndromes such as the Brugada syndrome and the long QT syndrome (LQTS). The aim of this study is to conduct a review of the literature on the mutations in the sodium channel complex responsible for heart disease and the implications of a close relationship between genetics and the clinical aspects of the main cardiac channelopathies, namely at the level of diagnosis, risk stratification, prognosis, screening of family members and treatment. METHODS The online Pubmed® database was used to search for articles published in this field in indexed journals. The MeSH database was used to define the following query: "Mutation [Mesh] AND Sodium Channels [Mesh] AND Heart Diseases [Mesh]", and articles published in the last 15 years, written in English or Portuguese and referring to research in human beings were included. CONCLUSIONS In the past few years, significant advances have been made to clarify the genetic and molecular basis of these syndromes. A greater understanding of the underlying pathophysiological mechanisms showed the importance of the relationship between genotype and phenotype and led to progress in the clinical approach to these patients. However, it is still necessary to improve diagnostic capacity, optimize risk stratification, and develop new specific treatments according to the genotype-phenotype binomial.
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Sinus Bradycardia in Carriers of the SCN5A-1795insD Mutation: Unraveling the Mechanism through Computer Simulations. Int J Mol Sci 2018; 19:ijms19020634. [PMID: 29473904 PMCID: PMC5855856 DOI: 10.3390/ijms19020634] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 11/25/2022] Open
Abstract
The SCN5A gene encodes the pore-forming α-subunit of the ion channel that carries the cardiac fast sodium current (INa). The 1795insD mutation in SCN5A causes sinus bradycardia, with a mean heart rate of 70 beats/min in mutation carriers vs. 77 beats/min in non-carriers from the same family (lowest heart rate 41 vs. 47 beats/min). To unravel the underlying mechanism, we incorporated the mutation-induced changes in INa into a recently developed comprehensive computational model of a single human sinoatrial node cell (Fabbri–Severi model). The 1795insD mutation reduced the beating rate of the model cell from 74 to 69 beats/min (from 49 to 43 beats/min in the simulated presence of 20 nmol/L acetylcholine). The mutation-induced persistent INa per se resulted in a substantial increase in beating rate. This gain-of-function effect was almost completely counteracted by the loss-of-function effect of the reduction in INa conductance. The further loss-of-function effect of the shifts in steady-state activation and inactivation resulted in an overall loss-of-function effect of the 1795insD mutation. We conclude that the experimentally identified mutation-induced changes in INa can explain the clinically observed sinus bradycardia. Furthermore, we conclude that the Fabbri–Severi model may prove a useful tool in understanding cardiac pacemaker activity in humans.
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66
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Fonseca DJ, Vaz da Silva MJ. Cardiac channelopathies: The role of sodium channel mutations. REVISTA PORTUGUESA DE CARDIOLOGIA (ENGLISH EDITION) 2018. [DOI: 10.1016/j.repce.2017.11.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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67
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Wang J, Ou SW, Bai YF, Wang YJ, Xu ZQD, Luan GM. Downregulation of adult and neonatal Nav1.5 in the dorsal root ganglia and axon of peripheral sensory neurons of rats with spared nerve injury. Int J Mol Med 2018; 41:2225-2232. [PMID: 29393394 DOI: 10.3892/ijmm.2018.3446] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 01/18/2018] [Indexed: 11/06/2022] Open
Abstract
Previous studies demonstrated that Nav1.5 splice variants, including Nav1.5a and Nav1.5c, were expressed in dorsal root ganglia (DRG) neurons. However, since nine Nav1.5 isoforms have been identified, whether other Nav1.5 splice variants, especially the neonatal Nav1.5 splice variant, express in the DRG neurons is still unknown. In this study, we systematically investigated the expression of adult and neonatal Nav1.5 isoforms in the DRG neurons and axon of peripheral sensory neurons of rats with spared nerve injury (SNI) by RT-PCR, DNA sequencing, restriction enzyme digestion, immunohistochemistry and immunofluorescence methods. The results demonstrated that both adult and neonatal Nav1.5 isoforms were expressed in the DRG neurons, but their expression ratio was ~2.5:1. In SNI rat models, the expression of both adult and neonatal Nav1.5 decreased by approximately a half in both mRNA and protein levels. In contrast, the expression of protein kinase C (PKC)-γ, one of the negative modulators for sodium currents, increased by ~1-fold. Taken together, this study first confirmed the expression of both adult and neonatal Nav1.5 isoforms in the DRG neurons and axon of peripheral sensory neurons of rat, but their expression level decreased in pain models. The upregulation of PKC-γ may directly or indirectly downregulate the expression of Nav1.5 isoforms in SNI rat models, which may further involve in the pathological process of neuropathic pain.
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Affiliation(s)
- Jun Wang
- Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing 100093, P.R. China
| | - Shao-Wu Ou
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang 110001, P.R. China
| | - Yun-Fei Bai
- Beijing Key Laboratory of Neural Regeneration and Repair, Department of Neurobiology, Capital Medical University, Beijing 100069, P.R. China
| | - Yun-Jie Wang
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang 110001, P.R. China
| | - Zhi-Qing David Xu
- Beijing Key Laboratory of Neural Regeneration and Repair, Department of Neurobiology, Capital Medical University, Beijing 100069, P.R. China
| | - Guo-Ming Luan
- Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing 100093, P.R. China
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Song Y, Belardinelli L. Enhanced basal late sodium current appears to underlie the age-related prolongation of action potential duration in guinea pig ventricular myocytes. J Appl Physiol (1985) 2017; 125:1329-1338. [PMID: 29357519 DOI: 10.1152/japplphysiol.00916.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aging hearts have prolonged QT interval and are vulnerable to oxidative stress. Because the QT interval indirectly reflects the action potential duration (APD), we examined the hypotheses that 1) the APD of ventricular myocytes increases with age; 2) the age-related prolongation of APD is due to an enhancement of basal late Na+ current (INaL); 3) inhibition of INaL may protect aging hearts from arrhythmogenic effects of hydrogen peroxide (H2O2). Experiments were performed on ventricular myocytes isolated from one-month (young) and one-year (old) guinea pigs (GPs). The APD of myocytes from old GPs was significantly longer than that from young GPs and was shortened by the INaL inhibitors GS967 and tetrodotoxin. The magnitude of INaL was significantly larger in myocytes from old than from young GPs. The CaMKII inhibitors KN-93 and AIP and the NaV1.5-channel blocker MTSEA blocked the INaL. There were no significant differences between myocytes from young and old GPs in L-type Ca2+ current and the rapidly- and slowly-activating delayed rectifier K+ currents, although the inward rectifier K+ current was slightly decreased in myocytes from old GPs. H2O2 induced more early afterdepolarizations in myocytes from old than from young GPs. The effect of H2O2 was attenuated by GS967. The results suggest that 1) the APD of myocytes from old GPs is prolonged, 2) a CaMKII-mediated increase in NaV1.5-channel INaL is responsible for the prolongation of APD, and 3) Inhibition of INaL may be beneficial for maintaining electrical stability under oxidative stress in myocytes of old GPs.
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Affiliation(s)
- Yejia Song
- Medicine, University of Florida, United States
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69
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Wang J, Ou SW, Zhang ZY, Qiu B, Wang YJ. Molecular expression of multiple Nav1.5 splice variants in the frontal lobe of the human brain. Int J Mol Med 2017; 41:915-923. [PMID: 29207052 PMCID: PMC5752160 DOI: 10.3892/ijmm.2017.3286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 11/22/2017] [Indexed: 11/29/2022] Open
Abstract
Voltage-gated sodium channels serve an essential role in the initiation and propagation of action potentials for central neurons. Previous studies have demonstrated that two novel variants of Nav1.5, designated Nav1.5e and Nav1.5f, were expressed in the human brain cortex. To date, nine distinct sodium channel isoforms of Nav1.5 have been identified. In the present study, the expression of Nav1.5 splice variants in the frontal lobe of the human brain cortex was systematically investigated. The results demonstrated that wild Nav1.5 and its splice variants, Nav1.5c and Nav1.5e, were expressed in the frontal lobe of the human brain cortex. Nav1.5a, Nav1.5b and Nav1.5d splice variants were not detected. However, the expression level of different Nav1.5 variants was revealed to vary. The expression ratio of wild Nav1.5 vs. Nav1.5c and Nav1.5e was approximately 5:1 and 1:5, respectively. Immunochemistry results revealed that Nav1.5 immunoreactivity was predominantly in neuronal cell bodies and processes, including axons and dendrites, whereas little immunoreactivity was detected in the glial components. These results revealed that a minimum of four Nav1.5 splice variants are expressed in the frontal lobe of the human brain cortex. This indicates that the previously reported tetrodotoxin-resistant sodium current was a compound product of different Nav1.5 variants. The present study revealed that Nav1.5 channels have a more abundant expression in the human brain than previously considered. It also provided further insight into the complexity and functional significance of Nav1.5 channels in human brain neurons.
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Affiliation(s)
- Jun Wang
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Shao-Wu Ou
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zhi-Yong Zhang
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Bo Qiu
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yun-Jie Wang
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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70
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Late sodium current associated cardiac electrophysiological and mechanical dysfunction. Pflugers Arch 2017; 470:461-469. [DOI: 10.1007/s00424-017-2079-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/27/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
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71
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Wang J, Ou SW, Wang YJ. Distribution and function of voltage-gated sodium channels in the nervous system. Channels (Austin) 2017; 11:534-554. [PMID: 28922053 DOI: 10.1080/19336950.2017.1380758] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons. To date, at least nine distinct sodium channel isoforms have been detected in the nervous system. Recent studies have identified that voltage-gated sodium channels not only play an essential role in the normal electrophysiological activities of neurons but also have a close relationship with neurological diseases. In this study, the latest research findings regarding the structure, type, distribution, and function of VGSCs in the nervous system and their relationship to neurological diseases, such as epilepsy, neuropathic pain, brain tumors, neural trauma, and multiple sclerosis, are reviewed in detail.
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Affiliation(s)
- Jun Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Shao-Wu Ou
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Yun-Jie Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
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Cardiac sodium channel antagonism - Translation of preclinical in vitro assays to clinical QRS prolongation. J Pharmacol Toxicol Methods 2017; 89:9-18. [PMID: 29042254 DOI: 10.1016/j.vascn.2017.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/31/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Cardiac sodium channel antagonists have historically been used to treat cardiac arrhythmias by preventing the reentry of the electrical impulse that could occur following myocardial damage. However, clinical studies have highlighted a significant increase in mortality associated with such treatment. Cardiac sodium channel antagonist activity is now seen as an off-target pharmacology that should be mitigated during the drug development process. The aim of this study was to examine the correlation between in vitro/ex vivo assays that are routinely used to measure Nav1.5 activity and determine the translatability of the individual assays to QRS prolongation in the clinic. METHODS A set of clinical compounds with known Nav1.5 activity was profiled in several in vitro/ex vivo assays (binding, membrane potential, patch clamp and the Langendorff isolated heart). Clinical data comprising compound exposure levels and changes in QRS interval were obtained from the literature. Sensitivity/specificity analysis was performed with respect to the clinical outcome. RESULTS The in vitro assays showed utility in predicting QRS prolongation in the clinic. Optimal thresholds were defined for each assay (binding: IC20; membrane potential: IC10; patch clamp: IC20) and sensitivity (69-88%) and specificity (53-84%) values were shown to be similar between assay formats. DISCUSSION The data provide clear statistical insight into the translatability of Nav1.5 antagonism data generated in vitro to potential clinical outcomes. These results improve our ability to understand the liability posed by such activity in novel development compounds at an early stage.
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Schweizer PA, Darche FF, Ullrich ND, Geschwill P, Greber B, Rivinius R, Seyler C, Müller-Decker K, Draguhn A, Utikal J, Koenen M, Katus HA, Thomas D. Subtype-specific differentiation of cardiac pacemaker cell clusters from human induced pluripotent stem cells. Stem Cell Res Ther 2017; 8:229. [PMID: 29037217 PMCID: PMC5644063 DOI: 10.1186/s13287-017-0681-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 09/07/2017] [Accepted: 09/25/2017] [Indexed: 12/11/2022] Open
Abstract
Background Human induced pluripotent stem cells (hiPSC) harbor the potential to differentiate into diverse cardiac cell types. Previous experimental efforts were primarily directed at the generation of hiPSC-derived cells with ventricular cardiomyocyte characteristics. Aiming at a straightforward approach for pacemaker cell modeling and replacement, we sought to selectively differentiate cells with nodal-type properties. Methods hiPSC were differentiated into spontaneously beating clusters by co-culturing with visceral endoderm-like cells in a serum-free medium. Subsequent culturing in a specified fetal bovine serum (FBS)-enriched cell medium produced a pacemaker-type phenotype that was studied in detail using quantitative real-time polymerase chain reaction (qRT-PCR), immunocytochemistry, and patch-clamp electrophysiology. Further investigations comprised pharmacological stimulations and co-culturing with neonatal cardiomyocytes. Results hiPSC co-cultured in a serum-free medium with the visceral endoderm-like cell line END-2 produced spontaneously beating clusters after 10–12 days of culture. The pacemaker-specific genes HCN4, TBX3, and TBX18 were abundantly expressed at this early developmental stage, while levels of sarcomeric gene products remained low. We observed that working-type cardiomyogenic differentiation can be suppressed by transfer of early clusters into a FBS-enriched cell medium immediately after beating onset. After 6 weeks under these conditions, sinoatrial node (SAN) hallmark genes remained at high levels, while working-type myocardial transcripts (NKX2.5, TBX5) were low. Clusters were characterized by regular activity and robust beating rates (70–90 beats/min) and were triggered by spontaneous Ca2+ transients recapitulating calcium clock properties of genuine pacemaker cells. They were responsive to adrenergic/cholinergic stimulation and able to pace neonatal rat ventricular myocytes in co-culture experiments. Action potential (AP) measurements of cells individualized from clusters exhibited nodal-type (63.4%) and atrial-type (36.6%) AP morphologies, while ventricular AP configurations were not observed. Conclusion We provide a novel culture media-based, transgene-free approach for targeted generation of hiPSC-derived pacemaker-type cells that grow in clusters and offer the potential for disease modeling, drug testing, and individualized cell-based replacement therapy of the SAN. Electronic supplementary material The online version of this article (doi:10.1186/s13287-017-0681-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patrick A Schweizer
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany. .,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.
| | - Fabrice F Darche
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Nina D Ullrich
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Institute of Physiology and Pathophysiology, Division of Cardiovascular Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Pascal Geschwill
- Institute of Physiology and Pathophysiology, Division of Neuro- and Sensory Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Boris Greber
- Department of Cell and Developmental Biology, Max-Planck-Institute for Molecular Biomedicine, Röntgenstrasse, 20, D-48149, Münster, Germany
| | - Rasmus Rivinius
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Karin Müller-Decker
- Unit Tumor Models, German Cancer Research Center (DKFZ), Heidelberg, INF 280, D-69120, Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Division of Neuro- and Sensory Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Jochen Utikal
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Dermato-Oncology (G300), German Cancer Research Center (DKFZ), Heidelberg, INF 280, D-69120, Heidelberg, Germany.,Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, Ruprecht-Karl University of Heidelberg, Theodor-Kutzer-Ufer 1-3, D-68167, Mannheim, Germany
| | - Michael Koenen
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Department of Molecular Neurobiology, Max-Planck-Institute for Medical Research, Jahnstrasse 29, D-69120, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
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Luo L, Ning F, Du Y, Song B, Yang D, Salvage SC, Wang Y, Fraser JA, Zhang S, Ma A, Wang T. Calcium-dependent Nedd4-2 upregulation mediates degradation of the cardiac sodium channel Nav1.5: implications for heart failure. Acta Physiol (Oxf) 2017; 221:44-58. [PMID: 28296171 DOI: 10.1111/apha.12872] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/08/2016] [Accepted: 03/03/2017] [Indexed: 12/18/2022]
Abstract
AIM Reductions in voltage-gated sodium channel (Nav1.5) function/expression provide a slowed-conduction substrate for cardiac arrhythmias. Nedd4-2, which is activated by calcium, post-translationally modulates Nav1.5. We aim to investigate whether elevated intracellular calcium ([Ca2+ ]i ) reduces Nav1.5 through Nedd4-2 and its role in heart failure (HF). METHODS Using a combination of biochemical, electrophysiological, cellular and in vivo methods, we tested the effect and mechanism of calcium on Nedd4-2 and in turn Nav1.5. RESULTS Increased [Ca2+ ]i , following 24-h ionomycin treatment, decreased sodium current (INa ) density and Nav1.5 protein without altering its mRNA in both neonatal rat cardiomyocytes (NRCMs) and HEK 293 cells stably expressing Nav1.5. The calcium chelator BAPTA-AM restored the reduced Nav1.5 and INa in NRCMs pre-treated by ionomycin. Nav1.5 was decreased by Nedd4-2 transfection and further decreased by 6-h ionomycin treatment. These effects were not observed in cells transfected with the catalytically inactive mutant, Nedd4-2 C801S, or with Y1977A-Nav1.5 mutant containing the impaired Nedd4-2 binding motif. Furthermore, elevated [Ca2+ ]i increased Nedd4-2, the interaction between Nedd4-2 and Nav1.5, and Nav1.5 ubiquitination. Nav1.5 protein is decreased, whereas Nedd4-2 is increased in volume-overload HF rat hearts, with increased co-localization of Nav1.5 with ubiquitin or Nedd4-2 as indicated by immunofluorescence staining. BAPTA-AM rescued the reduced Nav1.5 protein, INa and increased Nedd4-2 in hypertrophied NRCMs induced by isoproterenol or angiotensin II. CONCLUSION Calcium-mediated increases in Nedd4-2 downregulate Nav1.5 by ubiquitination. Nav1.5 is downregulated and co-localizes with Nedd4-2 and ubiquitin in failing rat heart. These data suggest a role of Nedd4-2 in Nav1.5 downregulation in HF.
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Affiliation(s)
- L. Luo
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - F. Ning
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - Y. Du
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - B. Song
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - D. Yang
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - S. C. Salvage
- Physiological Laboratory; University of Cambridge; Cambridge UK
| | - Y. Wang
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
| | - J. A. Fraser
- Physiological Laboratory; University of Cambridge; Cambridge UK
| | - S. Zhang
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston Ontario Canada
| | - A. Ma
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
- Key Laboratory of Molecular Cardiology; Xi'an Shaanxi Province China
- Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University); Ministry of Education; Xi'an China
| | - T. Wang
- Department of Cardiovascular Medicine; First Affiliated Hospital of Xi'an Jiaotong University; Xi'an China
- Key Laboratory of Molecular Cardiology; Xi'an Shaanxi Province China
- Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University); Ministry of Education; Xi'an China
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Zhao L, Yang XX, Yin YQ, Wu H, Kang Y, Lou JS. Acute and chronic effects of taurine magnesium coordination compound on cardiac sodium channel Nav1.5. Mol Med Rep 2017; 16:4259-4264. [PMID: 28765943 DOI: 10.3892/mmr.2017.7117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 04/12/2017] [Indexed: 11/05/2022] Open
Abstract
It has been previously demonstrated that taurine magnesium coordination compound (TMCC) produces antiarrhythmic effects in vivo. The present study investigated the acute and chronic effect of TMCC on sodium channels in HEK cells stably expressing human cardiac Nav1.5 sodium channels. The current amplitude, activation and inactivation kinetics, recovery time from inactivation, and use‑dependent block of sodium channels were analyzed using the whole‑cell patch clamp technique. Western blotting was used to analyze Nav1.5 expression following chronic TMCC treatment. In HEK cells expressing Nav1.5 channels, TMCC acutely inhibited Na+ currents in a dose‑dependent manner. In addition, acute application of TMCC shifted the activation and inactivation curves, and prolonged the recovery time from inactivation, but did not exhibit a use‑dependent block of Nav1.5. By contrast, chronic TMCC treatment only produced a use‑dependent block of Nav1.5 and downregulated Nav1.5 expression. The results of the present study suggested that TMCC may produce antiarrhythmic actions via acute inhibition of sodium channel currents and chronic downregulation of Nav1.5 expression.
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Affiliation(s)
- Lin Zhao
- International Medical School, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Xiao-Xu Yang
- Department of Pharmacy, Tianjin Medical University Metabolic Disease Hospital, Tianjin 300070, P.R. China
| | - Yong-Qiang Yin
- Department of Pharmacology, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Hong Wu
- Department of Pharmacology, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Yi Kang
- Department of Pharmacology, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Jian-Shi Lou
- Department of Pharmacology, Tianjin Medical University, Tianjin 300070, P.R. China
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Dulsat G, Palomeras S, Cortada E, Riuró H, Brugada R, Vergés M. Trafficking and localisation to the plasma membrane of Nav1.5 promoted by the β2 subunit is defective due to a β2 mutation associated with Brugada syndrome. Biol Cell 2017; 109:273-291. [DOI: 10.1111/boc.201600085] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 05/14/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Gemma Dulsat
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Sonia Palomeras
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Eric Cortada
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Helena Riuró
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Ramon Brugada
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
- Medical Sciences Department; University of Girona Medical School; Girona 17003 Spain
| | - Marcel Vergés
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
- Medical Sciences Department; University of Girona Medical School; Girona 17003 Spain
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77
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Sharifi M. Computational approaches to understand the adverse drug effect on potassium, sodium and calcium channels for predicting TdP cardiac arrhythmias. J Mol Graph Model 2017; 76:152-160. [PMID: 28756335 DOI: 10.1016/j.jmgm.2017.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 06/08/2017] [Accepted: 06/10/2017] [Indexed: 02/08/2023]
Abstract
Ion channels play a crucial role in the cardiovascular system. Our understanding of cardiac ion channel function has improved since their first discoveries. The flow of potassium, sodium and calcium ions across cardiomyocytes is vital for regular cardiac rhythm. Blockage of these channels, delays cardiac repolarization or tend to shorten repolarization and may induce arrhythmia. Detection of drug risk by channel blockade is considered essential for drug regulators. Advanced computational models can be used as an early screen for torsadogenic potential in drug candidates. New drug candidates that are determined to not cause blockage are more likely to pass successfully through preclinical trials and not be withdrawn later from the marketplace by manufacturer. Several different approved drugs, however, can cause a distinctive polymorphic ventricular arrhythmia known as torsade de pointes (TdP), which may lead to sudden death. The objective of the present study is to review the mechanisms and computational models used to assess the risk that a drug may TdP. KEY POINTS There is strong evidence from multiple studies that blockage of the L-type calcium current reduces risk of TdP. Blockage of sodium channels slows cardiac action potential conduction, however, not all sodium channel blocking antiarrhythmic drugs produce a significant effect, while late sodium channel block reduces TdP. Interestingly, there are some drugs that block the hERG potassium channel and therefore cause QT prolongation, but they are not associated with TdP. Recent studies confirmed the necessity of studying multiple distinctionic ion channels which are responsible for cardiac related diseases or TdP, to obtain an improved clinical TdP risk prediction of compound interactions and also for designing drugs.
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Affiliation(s)
- Mohsen Sharifi
- Division of Systems Biology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA.
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78
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Wang J, Ou SW, Bai YF, Wang YJ, Xu ZQD, Luan GM. Multiple Nav1.5 isoforms are functionally expressed in the brain and present distinct expression patterns compared with cardiac Nav1.5. Mol Med Rep 2017; 16:719-729. [PMID: 28560448 PMCID: PMC5482195 DOI: 10.3892/mmr.2017.6654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/08/2017] [Indexed: 02/01/2023] Open
Abstract
It has previously been demonstrated that there are various voltage gated sodium channel (Nav) 1.5 splice variants expressed in brain tissue. A total of nine Nav1.5 isoforms have been identified, however, the potential presence of further Nav1.5 variants expressed in brain neurons remains to be elucidated. The present study systematically investigated the expression of various Nav1.5 splice variants and their associated electrophysiological properties in the rat brain tissue, via biochemical analyses and whole-cell patch clamp recording. The results demonstrated that adult Nav1.5 was expressed in the rat, in addition to the neonatal Nav1.5, Nav1.5a and Nav1.5f isoforms. Further studies indicated that the expression level ratio of neonatal Nav1.5 compared with adult Nav1.5 decreased from 1:1 to 1:3 with age development from postnatal (P) day 0 to 90. This differed from the ratios observed in the developing rat hearts, in which the expression level ratio decreased from 1:4 to 1:19 from P0 to 90. The immunohistochemistry results revealed that Nav1.5 immunoreactivity was predominantly observed in neuronal cell bodies and processes, whereas decreased immunoreactivity was detected in the glial components. Electrophysiological analysis of Nav1.5 in the rat brain slices revealed that an Na current was detected in the presence of 300 nM tetrodotoxin (TTX), however this was inhibited by ~1 µM TTX. The TTX-resistant Na current was activated at −40 mV and reached the maximum amplitude at 0 mV. The results of the present study demonstrated that neonatal and adult Nav1.5 were expressed in the rat brain and electrophysiological analysis further confirmed the functional expression of Nav1.5 in brain neurons.
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Affiliation(s)
- Jun Wang
- Department of Neurosurgery, Beijing Sanbo Brain Hospital of Capital Medical University, Beijing 100093, P.R. China
| | - Shao-Wu Ou
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yun-Fei Bai
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing 100069, P.R. China
| | - Yun-Jie Wang
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zhi-Qing David Xu
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing 100069, P.R. China
| | - Guo-Ming Luan
- Department of Neurosurgery, Beijing Sanbo Brain Hospital of Capital Medical University, Beijing 100093, P.R. China
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79
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80
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Yang Z, Prinsen JK, Bersell KR, Shen W, Yermalitskaya L, Sidorova T, Luis PB, Hall L, Zhang W, Du L, Milne G, Tucker P, George AL, Campbell CM, Pickett RA, Shaffer CM, Chopra N, Yang T, Knollmann BC, Roden DM, Murray KT. Azithromycin Causes a Novel Proarrhythmic Syndrome. Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.115.003560. [PMID: 28408648 DOI: 10.1161/circep.115.003560] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/26/2017] [Indexed: 01/20/2023]
Abstract
BACKGROUND The widely used macrolide antibiotic azithromycin increases risk of cardiovascular and sudden cardiac death, although the underlying mechanisms are unclear. Case reports, including the one we document here, demonstrate that azithromycin can cause rapid, polymorphic ventricular tachycardia in the absence of QT prolongation, indicating a novel proarrhythmic syndrome. We investigated the electrophysiological effects of azithromycin in vivo and in vitro using mice, cardiomyocytes, and human ion channels heterologously expressed in human embryonic kidney (HEK 293) and Chinese hamster ovary (CHO) cells. METHODS AND RESULTS In conscious telemetered mice, acute intraperitoneal and oral administration of azithromycin caused effects consistent with multi-ion channel block, with significant sinus slowing and increased PR, QRS, QT, and QTc intervals, as seen with azithromycin overdose. Similarly, in HL-1 cardiomyocytes, the drug slowed sinus automaticity, reduced phase 0 upstroke slope, and prolonged action potential duration. Acute exposure to azithromycin reduced peak SCN5A currents in HEK cells (IC50=110±3 μmol/L) and Na+ current in mouse ventricular myocytes. However, with chronic (24 hour) exposure, azithromycin caused a ≈2-fold increase in both peak and late SCN5A currents, with findings confirmed for INa in cardiomyocytes. Mild block occurred for K+ currents representing IKr (CHO cells expressing hERG; IC50=219±21 μmol/L) and IKs (CHO cells expressing KCNQ1+KCNE1; IC50=184±12 μmol/L), whereas azithromycin suppressed L-type Ca++ currents (rabbit ventricular myocytes, IC50=66.5±4 μmol/L) and IK1 (HEK cells expressing Kir2.1, IC50=44±3 μmol/L). CONCLUSIONS Chronic exposure to azithromycin increases cardiac Na+ current to promote intracellular Na+ loading, providing a potential mechanistic basis for the novel form of proarrhythmia seen with this macrolide antibiotic.
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Affiliation(s)
- Zhenjiang Yang
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Joseph K Prinsen
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Kevin R Bersell
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Wangzhen Shen
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Liudmila Yermalitskaya
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Tatiana Sidorova
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Paula B Luis
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Lynn Hall
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Wei Zhang
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Liping Du
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Ginger Milne
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Patrick Tucker
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Alfred L George
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Courtney M Campbell
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Robert A Pickett
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Christian M Shaffer
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Nagesh Chopra
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Tao Yang
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Bjorn C Knollmann
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Dan M Roden
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Katherine T Murray
- From the Department of Medicine and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN.
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81
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Föhr KJ, Knippschild U, Herkommer A, Fauler M, Peifer C, Georgieff M, Adolph O. State-dependent block of voltage-gated sodium channels by the casein-kinase 1 inhibitor IC261. Invest New Drugs 2017; 35:277-289. [PMID: 28164251 DOI: 10.1007/s10637-017-0429-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 01/12/2017] [Indexed: 12/13/2022]
Abstract
Background and Purpose IC261 (3-[(2,4,6-trimethoxyphenyl)methylidenyl]-indolin-2-one) has previously been introduced as an isoform specific inhibitor of casein kinase 1 (CK1) causing cell cycle arrest or cell death of established tumor cell lines. However, it is reasonable to assume that not all antitumor activities of IC261 are mediated by the inhibition of CK1. Meanwhile there is growing evidence that functional voltage-gated sodium channels are also implicated in the progression of tumors as their blockage suppresses tumor migration and invasion of different tumor cell lines. Thus, we asked whether IC261 functionally inhibits voltage-gated sodium channels. Experimental Approach Electrophysiological experiments were performed using the patch-clamp technique at human heart muscle sodium channels heterologously expressed in human TsA cells. Key Results IC261 inhibits sodium channels in a state-dependent manner. IC261 does not interact with the open channel and has only a low affinity for the resting state of the hNav1.5 (human voltage-gated sodium channel; Kr: 120 μM). The efficacy of IC261 strongly increases with membrane depolarisation, indicating that the inactivated state is an important target. The results of different experimental approaches finally revealed an affinity of IC261 to the inactivated state between 1 and 2 μM. Conclusion and Implications IC261 inhibits sodium channels at a similar concentration necessary to reduce CK1δ/ε activity by 50% (IC50 value 1 μM). Thus, inhibition of sodium channels might contribute to the antitumor activity of IC261.
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Affiliation(s)
- Karl J Föhr
- Department of Anesthesiology, University Hospital of Ulm, Albert-Einstein-Allee 23, D-89075, Ulm, Germany.
| | - Uwe Knippschild
- Department of General and Visceral Surgery, University Hospital of Ulm, Albert-Einstein-Allee 23, D-89081, Ulm, Germany
| | - Anna Herkommer
- Department of Anesthesiology, University Hospital of Ulm, Albert-Einstein-Allee 23, D-89081, Ulm, Germany
| | - Michael Fauler
- Institute of General Physiology, University of Ulm, Albert-Einstein-Allee 11, D-89081, Ulm, Germany
| | - Christian Peifer
- Institute of Pharmacy, University of Kiel, Gutenbergstr. 76, D-24118, Kiel, Germany
| | - Michael Georgieff
- Department of Anesthesiology, University Hospital of Ulm, Albert-Einstein-Allee 23, D-89075, Ulm, Germany
| | - Oliver Adolph
- Department of Anesthesiology, University Hospital of Ulm, Albert-Einstein-Allee 23, D-89075, Ulm, Germany
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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83
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Genetic basis of dilated cardiomyopathy. Int J Cardiol 2016; 224:461-472. [PMID: 27736720 DOI: 10.1016/j.ijcard.2016.09.068] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 01/19/2023]
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84
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Kim DH, Lee SJ, Hahn SJ, Choi JS. Trifluoperazine blocks the human cardiac sodium channel, Na v1.5, independent of calmodulin. Biochem Biophys Res Commun 2016; 479:584-589. [PMID: 27666479 DOI: 10.1016/j.bbrc.2016.09.115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/22/2016] [Indexed: 11/20/2022]
Abstract
Trifluoperazine is a phenothiazine derivative which is mainly used in the management of schizophrenia and also acts as a calmodulin inhibitor. We used the whole-cell patch-clamp technique to study the effects of trifluoperazine on human Nav1.5 (hNav1.5) currents expressed in HEK293 cells. The 50% inhibitory concentration of trifluoperazine was 15.5 ± 0.3 μM and the Hill coefficient was 2.7 ± 0.1. The effects of trifluoperazine on hNav1.5 were completely and repeatedly reversible after washout. Trifluoperazine caused depolarizing shifts in the activation and hyperpolarizing shifts in the steady-state inactivation of hNav1.5. Trifluoperazine also showed strong use-dependent inhibition of hNav1.5. The blockade of hNav1.5 currents by trifluoperazine was not affected by the whole cell dialysis of the calmodulin inhibitory peptide. Our results indicated that trifluoperazine blocks hNav1.5 current in concentration-, state- and use-dependent manners rather than via calmodulin inhibition.
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Affiliation(s)
- Dong-Hyun Kim
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Su-Jin Lee
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Sang June Hahn
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Jin-Sung Choi
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea.
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85
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Pre- and Delayed Treatments With Ranolazine Ameliorate Ventricular Arrhythmias and Nav1.5 Downregulation in Ischemic/Reperfused Rat Hearts. J Cardiovasc Pharmacol 2016; 68:269-279. [DOI: 10.1097/fjc.0000000000000412] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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86
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Embryonic type Na + channel β-subunit, SCN3B masks the disease phenotype of Brugada syndrome. Sci Rep 2016; 6:34198. [PMID: 27677334 PMCID: PMC5039759 DOI: 10.1038/srep34198] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/09/2016] [Indexed: 12/13/2022] Open
Abstract
SCN5A is abundant in heart and has a major role in INa. Loss-of-function mutation in SCN5A results in Brugada syndrome (BrS), which causes sudden death in adults. It remains unclear why disease phenotype does not manifest in the young even though mutated SCN5A is expressed in the young. The aim of the present study is to elucidate the timing of the disease manifestation in BrS. A gain-of-function mutation in SCN5A also results in Long QT syndrome type 3 (LQTS3), leading to sudden death in the young. Induced pluripotent stem cells (iPSCs) were generated from a patient with a mixed phenotype of LQTS3 and BrS with the E1784K SCN5A mutation. Here we show that electrophysiological analysis revealed that LQTS3/BrS iPSC-derived cardiomyocytes recapitulate the phenotype of LQTS3 but not BrS. Each β-subunit of the sodium channel is differentially expressed in embryonic and adult hearts. SCN3B is highly expressed in embryonic hearts and iPSC-derived cardiomyocytes. A heterologous expression system revealed that INa of mutated SCN5A is decreased and SCN3B augmented INa of mutated SCN5A. Knockdown of SCN3B in LQTS3/BrS iPSC-derived cardiomyocytes successfully unmasked the phenotype of BrS. Isogenic control of LQTS3/BrS (corrected-LQTS3/BrS) iPSC-derived cardiomyocytes gained the normal electrophysiological properties.
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87
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Xu Q, Patel D, Zhang X, Veenstra RD. Changes in cardiac Nav1.5 expression, function, and acetylation by pan-histone deacetylase inhibitors. Am J Physiol Heart Circ Physiol 2016; 311:H1139-H1149. [PMID: 27638876 DOI: 10.1152/ajpheart.00156.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 08/24/2016] [Indexed: 12/19/2022]
Abstract
Histone deacetylase (HDAC) inhibitors are small molecule anticancer therapeutics that exhibit limiting cardiotoxicities including QT interval prolongation and life-threatening cardiac arrhythmias. Because the molecular mechanisms for HDAC inhibitor-induced cardiotoxicity are poorly understood, we performed whole cell patch voltage-clamp experiments to measure cardiac sodium currents (INa) from wild-type neonatal mouse ventricular or human-induced pluripotent stem cell-derived cardiomyocytes treated with trichostatin A (TSA), vorinostat (VOR), or romidepsin (FK228). All three pan-HDAC inhibitors dose dependently decreased peak INa density and shifted the voltage activation curve 3- to 8-mV positive. Increases in late INa were not observed despite a moderate slowing of the inactivation rate at low activating potentials (<-40 mV). Scn5a mRNA levels were not significantly altered but NaV1.5 protein levels were significantly reduced. Immunoprecipitation with anti-NaV1.5 and Western blotting with anti-acetyl-lysine antibodies indicated that NaV1.5 acetylation is increased in vivo after HDAC inhibition. FK228 inhibited total cardiac HDAC activity with two apparent IC50s of 5 nM and 1.75 μM, consistent with previous findings with TSA and VOR. FK228 also decreased ventricular gap junction conductance (gj), again consistent with previous findings. We conclude that pan-HDAC inhibition reduces cardiac INa density and NaV1.5 protein levels without affecting late INa amplitude and, thus, probably does not contribute to the reported QT interval prolongation and arrhythmias associated with pan-HDAC inhibitor therapies. Conversely, reductions in gj may enhance the occurrence of triggered activity by limiting electrotonic inhibition and, combined with reduced INa, slow myocardial conduction and increase vulnerability to reentrant arrhythmias.
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Affiliation(s)
- Qin Xu
- Department of Pharmacology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York; and
| | - Dakshesh Patel
- Department of Pharmacology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York; and
| | - Xian Zhang
- Department of Pharmacology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York; and
| | - Richard D Veenstra
- Department of Pharmacology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York; and .,Department of Cell and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York
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88
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Ríos-Pérez EB, García-Castañeda M, Monsalvo-Villegas A, Avila G. Chronic atrial ionic remodeling by aldosterone: potentiation of L-type Ca 2+ channels and its arrhythmogenic significance. Pflugers Arch 2016; 468:1823-1835. [PMID: 27631154 DOI: 10.1007/s00424-016-1876-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/31/2016] [Accepted: 09/05/2016] [Indexed: 11/25/2022]
Abstract
It is widely accepted that aldosterone induces atrial fibrillation (AF) by promoting structural changes, but its effects on the function of primary atrial myocytes remain unknown. We have investigated this point in adult rat atrial myocytes, chronically exposed to the hormone. This treatment produced larger amplitude of Ca2+ transients, longer action potential (AP) duration, and higher incidence of unsynchronized Ca2+ oscillations. Moreover, it also gave rise to increases in both cell membrane capacitance (Cm, 30 %) and activity of L-type Ca2+ channels (LTCCs, 100 %). Concerning K+ currents, a twofold increase was also observed, but only in a delayed rectifier component (IKsus). Interestingly, the maximal conductance (Gmax) of Na+ channels was also enhanced, but it occurred in the face of a negative shift in the voltage dependence of inactivation. Thus, at physiological potentials, a decreased fraction of available channels neutralized the effect on GNa-max. With regard to the effects on both Cm and LTCCs, they involved activation of mineralocorticoid receptors (MRs), were dose-dependent (EC50 ∼20-130 nM), and developed and recovered in days. Neither gating currents nor protein levels of LTCCs were altered. Instead, the effect on LTCCs was mimicked by cAMP, reverted by a PKA inhibitor, and attenuated by a nitric oxide donor (short-term exposures). Both EGTA and the antioxidant NAC prevented the increase in Cm, without significantly interfering with the upregulation of LTCCs. Overall, these results show that chronic exposures to aldosterone result in dire functional changes at the single myocyte level, which may explain the link between aldosteronism and AF.
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Affiliation(s)
- Erick B Ríos-Pérez
- Department of Biochemistry, Cinvestav-IPN, AP 14-740, México City, DF 07000, México
| | | | | | - Guillermo Avila
- Department of Biochemistry, Cinvestav-IPN, AP 14-740, México City, DF 07000, México.
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89
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DeMarco KR, Clancy CE. Cardiac Na Channels: Structure to Function. CURRENT TOPICS IN MEMBRANES 2016; 78:287-311. [PMID: 27586288 DOI: 10.1016/bs.ctm.2016.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heart rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. Opening of the primary cardiac voltage-gated sodium (NaV1.5) channel initiates cellular depolarization and the propagation of an electrical action potential that promotes coordinated contraction of the heart. The regularity of these contractile waves is critically important since it drives the primary function of the heart: to act as a pump that delivers blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. Perturbations to NaV1.5 may alter the structure, and hence the function, of the ion channel and are associated downstream with a wide variety of cardiac conduction pathologies, such as arrhythmias.
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Affiliation(s)
- K R DeMarco
- University of California, Davis, Davis, CA, United States
| | - C E Clancy
- University of California, Davis, Davis, CA, United States
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90
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Shenasa M, Assadi H, Heidary S, Shenasa H. Ranolazine: Electrophysiologic Effect, Efficacy, and Safety in Patients with Cardiac Arrhythmias. Card Electrophysiol Clin 2016; 8:467-479. [PMID: 27261835 DOI: 10.1016/j.ccep.2016.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ranolazine is currently approved as an antianginal agent in patients with chronic angina (class IIA). Ranolazine exhibits antiarrhythmic effects that are related to its multichannel blocking effect, predominantly inhibition of late sodium (late INa) current and the rapid potassium rectifier current (IKr), as well as ICa, late ICa, and INa-Ca. It also suppresses the early and delayed after depolarizations. Ranolazine is effective in the suppression of atrial and ventricular arrhythmias (off-label use) without significant proarrhythmic effect. Currently, ongoing trials are evaluating the efficacy and safety of ranolazine in patients with cardiac arrhythmias; preliminary results suggest that ranolazine, when used alone or in combination with dronedarone, is safe and effective in reducing atrial fibrillation. Ranolazine is not currently approved by the US Food and Drug Administration as an antiarrhythmic agent.
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Affiliation(s)
- Mohammad Shenasa
- Heart and Rhythm Medical Group, Department of Cardiovascular Services, O'Connor Hospital, 105 North Bascom Avenue, San Jose, CA 95128, USA.
| | - Hamid Assadi
- Heart and Rhythm Medical Group, Department of Cardiovascular Services, O'Connor Hospital, 105 North Bascom Avenue, San Jose, CA 95128, USA
| | - Shahriar Heidary
- Heart and Rhythm Medical Group, Department of Cardiovascular Services, O'Connor Hospital, 105 North Bascom Avenue, San Jose, CA 95128, USA
| | - Hossein Shenasa
- Heart and Rhythm Medical Group, Department of Cardiovascular Services, O'Connor Hospital, 105 North Bascom Avenue, San Jose, CA 95128, USA
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91
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Franco D, Lozano-Velasco E, Aranega A. Gene regulatory networks in atrial fibrillation. World J Med Genet 2016; 6:1-16. [DOI: 10.5496/wjmg.v6.i1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/15/2015] [Accepted: 02/17/2016] [Indexed: 02/06/2023] Open
Abstract
Atrial fibrillation (AF) is the most frequent arrhythmogenic syndrome in humans. With an estimate incidence of 1%-2% in the general population, AF raises up to almost 10%-12% in 80+ years. Thus, AF represents nowadays a highly prevalent medical problem generating a large economic burden. At the electrophysiological level, distinct mechanisms have been elucidated. Yet, despite its prevalence, the genetic and molecular culprits of this pandemic cardiac electrophysiological abnormality have remained largely obscure. Molecular genetics of AF familiar cases have demonstrated that single nucleotide mutations in distinct genes encoding for ion channels underlie the onset of AF, albeit such alterations only explain a minor subset of patients with AF. In recent years, analyses by means of genome-wide association studies have unraveled a more complex picture of the etiology of AF, pointing out to distinct cardiac-enriched transcription factors, as well as to other regulatory genes. Furthermore a new layer of regulatory mechanisms have emerged, i.e., post-transcriptional regulation mediated by non-coding RNA, which have been demonstrated to exert pivotal roles in cardiac electrophysiology. In this manuscript, we aim to provide a comprehensive review of the genetic regulatory networks that if impaired exert electrophysiological abnormalities that contribute to the onset, and subsequently, on self-perpetuation of AF.
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92
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Jeevaratnam K, Guzadhur L, Goh YM, Grace AA, Huang CLH. Sodium channel haploinsufficiency and structural change in ventricular arrhythmogenesis. Acta Physiol (Oxf) 2016; 216:186-202. [PMID: 26284956 DOI: 10.1111/apha.12577] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/11/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022]
Abstract
Normal cardiac excitation involves orderly conduction of electrical activation and recovery dependent upon surface membrane, voltage-gated, sodium (Na(+) ) channel α-subunits (Nav 1.5). We summarize experimental studies of physiological and clinical consequences of loss-of-function Na(+) channel mutations. Of these conditions, Brugada syndrome (BrS) and progressive cardiac conduction defect (PCCD) are associated with sudden, often fatal, ventricular tachycardia (VT) or fibrillation. Mouse Scn5a(+/-) hearts replicate important clinical phenotypes modelling these human conditions. The arrhythmic phenotype is associated not only with the primary biophysical change but also with additional, anatomical abnormalities, in turn dependent upon age and sex, each themselves exerting arrhythmic effects. Available evidence suggests a unified binary scheme for the development of arrhythmia in both BrS and PCCD. Previous biophysical studies suggested that Nav 1.5 deficiency produces a background electrophysiological defect compromising conduction, thereby producing an arrhythmic substrate unmasked by flecainide or ajmaline challenge. More recent reports further suggest a progressive decline in conduction velocity and increase in its dispersion particularly in ageing male Nav 1.5 haploinsufficient compared to WT hearts. This appears to involve a selective appearance of slow conduction at the expense of rapidly conducting pathways with changes in their frequency distributions. These changes were related to increased cardiac fibrosis. It is thus the combination of the structural and biophysical changes both accentuating arrhythmic substrate that may produce arrhythmic tendency. This binary scheme explains the combined requirement for separate, biophysical and structural changes, particularly occurring in ageing Nav 1.5 haploinsufficient males in producing clinical arrhythmia.
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Affiliation(s)
- K. Jeevaratnam
- Faculty of Health and Medical Science; University of Surrey; Guilford UK
- Perdana University - Royal College of Surgeons Ireland; Serdang Selangor Darul Ehsan Malaysia
| | - L. Guzadhur
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Niche Science & Technology; Richmond UK
| | - Y. M. Goh
- Department of Preclinical Sciences; Faculty of Veterinary Medicine; University Putra Malaysia; Serdang Selangor Darul Ehsan Malaysia
| | - A. A. Grace
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
| | - C. L.-H. Huang
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Physiological Laboratory; University of Cambridge; Cambridge UK
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93
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Loussouarn G, Sternberg D, Nicole S, Marionneau C, Le Bouffant F, Toumaniantz G, Barc J, Malak OA, Fressart V, Péréon Y, Baró I, Charpentier F. Physiological and Pathophysiological Insights of Nav1.4 and Nav1.5 Comparison. Front Pharmacol 2016; 6:314. [PMID: 26834636 PMCID: PMC4712308 DOI: 10.3389/fphar.2015.00314] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/21/2015] [Indexed: 12/19/2022] Open
Abstract
Mutations in Nav1.4 and Nav1.5 α-subunits have been associated with muscular and cardiac channelopathies, respectively. Despite intense research on the structure and function of these channels, a lot of information is still missing to delineate the various physiological and pathophysiological processes underlying their activity at the molecular level. Nav1.4 and Nav1.5 sequences are similar, suggesting structural and functional homologies between the two orthologous channels. This also suggests that any characteristics described for one channel subunit may shed light on the properties of the counterpart channel subunit. In this review article, after a brief clinical description of the muscular and cardiac channelopathies related to Nav1.4 and Nav1.5 mutations, respectively, we compare the knowledge accumulated in different aspects of the expression and function of Nav1.4 and Nav1.5 α-subunits: the regulation of the two encoding genes (SCN4A and SCN5A), the associated/regulatory proteins and at last, the functional effect of the same missense mutations detected in Nav1.4 and Nav1.5. First, it appears that more is known on Nav1.5 expression and accessory proteins. Because of the high homologies of Nav1.5 binding sites and equivalent Nav1.4 sites, Nav1.5-related results may guide future investigations on Nav1.4. Second, the analysis of the same missense mutations in Nav1.4 and Nav1.5 revealed intriguing similarities regarding their effects on membrane excitability and alteration in channel biophysics. We believe that such comparison may bring new cues to the physiopathology of cardiac and muscular diseases.
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Affiliation(s)
- Gildas Loussouarn
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Damien Sternberg
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Centres de Référence des Canalopathies Musculaires et des Maladies Neuro-musculaires Paris-EstParis, France; Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et MyogénétiqueParis, France
| | - Sophie Nicole
- Institut National de la Santé et de la Recherche Médicale, U1127Paris, France; Sorbonne Universités, Université Pierre-et-Marie-Curie, UMR S1127Paris, France; Centre National de la Recherche Scientifique, UMR 7225Paris, France; Institut du Cerveau et de la Moelle Épinière, ICMParis, France
| | - Céline Marionneau
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Francoise Le Bouffant
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Gilles Toumaniantz
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Julien Barc
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Olfat A Malak
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Véronique Fressart
- Assistance Publique - Hôpitaux de Paris (AP-HP), Hôpital de la Pitié Salpêtrière, Service de Biochimie Métabolique, Unité de Cardiogénétique et Myogénétique Paris, France
| | - Yann Péréon
- Centre Hospitalier Universitaire de Nantes, Centre de Référence Maladies Neuromusculaires Nantes-AngersNantes, France; Atlantic Gene Therapies - Biotherapy Institute for Rare DiseasesNantes, France
| | - Isabelle Baró
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France
| | - Flavien Charpentier
- Institut National de la Santé et de la Recherche Médicale, UMR 1087, l'Institut du ThoraxNantes, France; Centre National de la Recherche Scientifique, UMR 6291Nantes, France; Université de NantesNantes, France; Centre Hospitalier Universitaire de Nantes, l'Institut du ThoraxNantes, France
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94
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Abstract
The zebrafish (Danio rerio) has become a popular model for human cardiac diseases and pharmacology including cardiac arrhythmias and its electrophysiological basis. Notably, the phenotype of zebrafish cardiac action potential is similar to the human cardiac action potential in that both have a long plateau phase. Also the major inward and outward current systems are qualitatively similar in zebrafish and human hearts. However, there are also significant differences in ionic current composition between human and zebrafish hearts, and the molecular basis and pharmacological properties of human and zebrafish cardiac ionic currents differ in several ways. Cardiac ionic currents may be produced by non-orthologous genes in zebrafish and humans, and paralogous gene products of some ion channels are expressed in the zebrafish heart. More research on molecular basis of cardiac ion channels, and regulation and drug sensitivity of the cardiac ionic currents are needed to enable rational use of the zebrafish heart as an electrophysiological model for the human heart.
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Affiliation(s)
- Matti Vornanen
- a Department of Biology , University of Eastern Finland , Joensuu , Finland
| | - Minna Hassinen
- a Department of Biology , University of Eastern Finland , Joensuu , Finland
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95
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Kharatmal S, Singh J, Sharma S. Comparative evaluation of in vitro and in vivo high glucose-induced alterations in voltage-gated tetrodotoxin-resistant sodium channel: Effects attenuated by sodium channel blockers. Neuroscience 2015; 305:183-96. [DOI: 10.1016/j.neuroscience.2015.07.085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/24/2015] [Accepted: 07/31/2015] [Indexed: 10/23/2022]
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96
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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97
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Gintant G. Cardiac Sodium Current (Na v1.5). METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2015. [DOI: 10.1002/9783527673643.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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98
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Zhao C, Wang L, Ma X, Zhu W, Yao L, Cui Y, Liu Y, Li J, Liang X, Sun Y, Li L, Chen YH. Cardiac Nav 1.5 is modulated by ubiquitin protein ligase E3 component n-recognin UBR3 and 6. J Cell Mol Med 2015; 19:2143-52. [PMID: 26059563 PMCID: PMC4568919 DOI: 10.1111/jcmm.12588] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 03/03/2015] [Indexed: 11/29/2022] Open
Abstract
The voltage-gated Na+ channel Nav1.5 is essential for action potential (AP) formation and electrophysiological homoeostasis in the heart. The ubiquitin–proteasome system (UPS) is a major degradative system for intracellular proteins including ion channels. The ubiquitin protein ligase E3 component N-recognin (UBR) family is a part of the UPS; however, their roles in regulating cardiac Nav1.5 channels remain elusive. Here, we found that all of the UBR members were expressed in cardiomyocytes. Individual knockdown of UBR3 or UBR6, but not of other UBR members, significantly increased Nav1.5 protein levels in neonatal rat ventricular myocytes, and this effect was verified in HEK293T cells expressing Nav1.5 channels. The UBR3/6-dependent regulation of Nav1.5 channels was not transcriptionally mediated, and pharmacological inhibition of protein biosynthesis failed to counteract the increase in Nav1.5 protein caused by UBR3/6 reduction, suggesting a degradative modulation of UBR3/6 on Nav1.5. Furthermore, the effects of UBR3/6 knockdown on Nav1.5 proteins were abolished under the inhibition of proteasome activity, and UBR3/6 knockdown reduced Nav1.5 ubiquitylation. The double UBR3–UBR6 knockdown resulted in comparable increases in Nav1.5 proteins to that observed for single knockdown of either UBR3 or UBR6. Electrophysiological recordings showed that UBR3/6 reduction-mediated increase in Nav1.5 protein enhanced the opening of Nav1.5 channels and thereby the amplitude of the AP. Thus, our findings indicate that UBR3/6 regulate cardiomyocyte Nav1.5 channel protein levels via the ubiquitin–proteasome pathway. It is likely that UBR3/6 have the potential to be a therapeutic target for cardiac arrhythmias.
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Affiliation(s)
- Chunxia Zhao
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Lijie Wang
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xiue Ma
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Weidong Zhu
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Lei Yao
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China
| | - Yingyu Cui
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Yi Liu
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jun Li
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Xingqun Liang
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Yunfu Sun
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Li Li
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Yi-Han Chen
- Key Laboratory of Arrhythmias of the Ministry of Education of China, East Hospital, Tongji University School of Medicine, Shanghai, China.,Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Research Center for Translational Medicine, Tongji University School of Medicine, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
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99
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Potet F, Beckermann TM, Kunic JD, George AL. Intracellular calcium attenuates late current conducted by mutant human cardiac sodium channels. Circ Arrhythm Electrophysiol 2015; 8:933-41. [PMID: 26022185 DOI: 10.1161/circep.115.002760] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 05/07/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Mutations of the cardiac voltage-gated sodium channel (SCN5A gene encoding voltage-gated sodium channel [NaV1.5]) cause congenital long-QT syndrome type 3 (LQT3). Most NaV1.5 mutations associated with LQT3 promote a mode of sodium channel gating in which some channels fail to inactivate, contributing to increased late sodium current (INaL), which is directly responsible for delayed repolarization and prolongation of the QT interval. LQT3 patients have highest risk of arrhythmia during sleep or during periods of slow heart rate. During exercise (high heart rate), there is elevated steady-state intracellular free calcium (Ca(2+)) concentration. We hypothesized that higher levels of intracellular Ca(2+) may lower arrhythmia risk in LQT3 subjects through effects on INaL. METHODS AND RESULTS We tested this idea by examining the effects of varying intracellular Ca(2+) concentrations on the level of INaL in cells expressing a typical LQT3 mutation, delKPQ, and another SCN5A mutation, R225P. We found that elevated intracellular Ca(2+) concentration significantly reduced INaL conducted by mutant channels but not wild-type channels. This attenuation of INaL in delKPQ expressing cells by Ca(2+) was not affected by the CaM kinase II inhibitor KN-93 but was partially attenuated by truncating the C-terminus of the channel. CONCLUSIONS We conclude that intracellular Ca(2+) contributes to the regulation of INaL conducted by NaV1.5 mutants and propose that, during excitation-contraction coupling, elevated intracellular Ca(2+) suppresses mutant channel INaL and protects cells from delayed repolarization. These findings offer a plausible explanation for the lower arrhythmia risk in LQT3 subjects during fast heart rates.
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Affiliation(s)
- Franck Potet
- From the Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (F.P., A.L.G.); and Department of Medicine (F.P., J.D.K., A.L.G.) and Department of Pharmacology (T.M.B., A.L.G.), Vanderbilt University, Nashville, TN.
| | - Thomas M Beckermann
- From the Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (F.P., A.L.G.); and Department of Medicine (F.P., J.D.K., A.L.G.) and Department of Pharmacology (T.M.B., A.L.G.), Vanderbilt University, Nashville, TN
| | - Jennifer D Kunic
- From the Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (F.P., A.L.G.); and Department of Medicine (F.P., J.D.K., A.L.G.) and Department of Pharmacology (T.M.B., A.L.G.), Vanderbilt University, Nashville, TN
| | - Alfred L George
- From the Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (F.P., A.L.G.); and Department of Medicine (F.P., J.D.K., A.L.G.) and Department of Pharmacology (T.M.B., A.L.G.), Vanderbilt University, Nashville, TN
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100
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León Ariza HH, Valenzuela Faccini N, Rojas Ortega AC, Botero Rosas DA. Nav1.5 cardiac sodium channels, regulation and clinical implications. REVISTA DE LA FACULTAD DE MEDICINA 2015. [DOI: 10.15446/revfacmed.v62n4.44015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
<p>Voltage-gated sodium channels constitute a group of membrane<br />proteins widely distributed thought the body. In the heart, there<br />are at least six different isoforms, being the Nav1.5 the most<br />abundant. The channel is composed of an α subunit that is formed<br />by four domains of six segments each, and four much smaller β<br />subunits that provide stability and integrate other channels into<br />the α subunit. The function of the Nav1.5 channel is modulated<br />by intracellular cytoskeleton proteins, extracellular proteins,<br />calcium concentration, free radicals, and medications, among<br />other things. The study of the channel and its alterations has<br />grown thanks to its association with pathogenic conditions such<br />as Long QT syndrome, Brugada syndrome, atrial fibrillation,<br />arrhythmogenic ventricular dysplasia and complications during<br />ischemic processes.</p>
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