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Iamshanova O, Hämmerli AF, Ramaye E, Seljmani A, Ross-Kaschitza D, Schärz N, Essers M, Guichard S, Rougier JS, Abriel H. The dispensability of 14-3-3 proteins for the regulation of human cardiac sodium channel Nav1.5. PLoS One 2024; 19:e0298820. [PMID: 38452156 PMCID: PMC10919853 DOI: 10.1371/journal.pone.0298820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 01/30/2024] [Indexed: 03/09/2024] Open
Abstract
BACKGROUND 14-3-3 proteins are ubiquitous proteins that play a role in cardiac physiology (e.g., metabolism, development, and cell cycle). Furthermore, 14-3-3 proteins were proposed to regulate the electrical function of the heart by interacting with several cardiac ion channels, including the voltage-gated sodium channel Nav1.5. Given the many cardiac arrhythmias associated with Nav1.5 dysfunction, understanding its regulation by the protein partners is crucial. AIMS In this study, we aimed to investigate the role of 14-3-3 proteins in the regulation of the human cardiac sodium channel Nav1.5. METHODS AND RESULTS Amongst the seven 14-3-3 isoforms, only 14-3-3η (encoded by YWHAH gene) weakly co-immunoprecipitated with Nav1.5 when heterologously co-expressed in tsA201 cells. Total and cell surface expression of Nav1.5 was however not modified by 14-3-3η overexpression or inhibition with difopein, and 14-3-3η did not affect physical interaction between Nav1.5 α-α subunits. The current-voltage relationship and the amplitude of Nav1.5-mediated sodium peak current density were also not changed. CONCLUSIONS Our findings illustrate that the direct implication of 14-3-3 proteins in regulating Nav1.5 is not evident in a transformed human kidney cell line tsA201.
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Affiliation(s)
- Oksana Iamshanova
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Anne-Flore Hämmerli
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Elise Ramaye
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Arbresh Seljmani
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
- medi—Center for Medical Education, Bern, Switzerland
| | - Daniela Ross-Kaschitza
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Noëlia Schärz
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
- medi—Center for Medical Education, Bern, Switzerland
| | - Maria Essers
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Sabrina Guichard
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Jean-Sébastien Rougier
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Hugues Abriel
- Faculty of Medicine, Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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2
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Tarantino A, Ciconte G, Ghiroldi A, Mastrocinque F, Micaglio E, Boccellino A, Negro G, Piccoli M, Cirillo F, Vicedomini G, Santinelli V, Anastasia L, Pappone C. Challenges in Brugada Syndrome Stratification: Investigating SCN5A Mutation Localization and Clinical Phenotypes. Int J Mol Sci 2023; 24:16658. [PMID: 38068978 PMCID: PMC10706434 DOI: 10.3390/ijms242316658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/15/2023] [Accepted: 11/19/2023] [Indexed: 12/18/2023] Open
Abstract
Brugada Syndrome (BrS) is a genetic heart condition linked to sudden cardiac death. Though the SCN5A gene is primarily associated with BrS, there is a lack of comprehensive studies exploring the connection between SCN5A mutation locations and the clinical presentations of the syndrome. This study aimed to address this gap and gain further understanding of the syndrome. The investigation classified 36 high-risk BrS patients based on SCN5A mutations within the transmembrane/structured (TD) and intra-domain loops (IDLs) lacking a 3D structure. We characterized the intrinsically disordered regions (IDRs) abundant in IDLs, using bioinformatics tools to predict IDRs and post-translational modifications (PTMs) in NaV1.5. Interestingly, it was found that current predictive tools often underestimate the impacts of mutations in IDLs and disordered regions. Moreover, patients with SCN5A mutations confined to IDL regions-previously deemed 'benign'-displayed clinical symptoms similar to those carrying 'damaging' variants. Our research illuminates the difficulty in stratifying patients based on SCN5A mutation locations, emphasizing the vital role of IDLs in the NaV1.5 channel's functioning and protein interactions. We advocate for caution when using predictive tools for mutation evaluation in these regions and call for the development of improved strategies in accurately assessing BrS risk.
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Affiliation(s)
- Adriana Tarantino
- Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (A.T.); (M.P.); (F.C.)
- School of Medicine, University Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milan, Italy;
| | - Giuseppe Ciconte
- School of Medicine, University Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milan, Italy;
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Andrea Ghiroldi
- Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (A.T.); (M.P.); (F.C.)
| | - Flavio Mastrocinque
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Emanuele Micaglio
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Antonio Boccellino
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Gabriele Negro
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Marco Piccoli
- Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (A.T.); (M.P.); (F.C.)
| | - Federica Cirillo
- Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (A.T.); (M.P.); (F.C.)
| | - Gabriele Vicedomini
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Vincenzo Santinelli
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
| | - Luigi Anastasia
- Institute for Molecular and Translational Cardiology (IMTC), IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (A.T.); (M.P.); (F.C.)
- School of Medicine, University Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milan, Italy;
| | - Carlo Pappone
- School of Medicine, University Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milan, Italy;
- Arrhythmology Department, IRCCS Policlinico San Donato, Piazza Malan 2, San Donato Milanese, 20097 Milan, Italy; (F.M.); (E.M.); (A.B.); (G.N.); (G.V.); (V.S.)
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Yoon JY, Greiner AM, Jacobs JS, Kim YR, Rasmussen TP, Kutschke WJ, Matasic DS, Vikram A, Gaddam RR, Mehdi H, Irani K, London B. SUMOylation of the cardiac sodium channel Na V1.5 modifies inward current and cardiac excitability. Heart Rhythm 2023; 20:1548-1557. [PMID: 37543305 DOI: 10.1016/j.hrthm.2023.07.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 07/07/2023] [Accepted: 07/31/2023] [Indexed: 08/07/2023]
Abstract
BACKGROUND Decreased peak sodium current (INa) and increased late sodium current (INa,L), through the cardiac sodium channel NaV1.5 encoded by SCN5A, cause arrhythmias. Many NaV1.5 posttranslational modifications have been reported. A recent report concluded that acute hypoxia increases INa,L by increasing a small ubiquitin-like modifier (SUMOylation) at K442-NaV1.5. OBJECTIVE The purpose of this study was to determine whether and by what mechanisms SUMOylation alters INa, INa,L, and cardiac electrophysiology. METHODS SUMOylation of NaV1.5 was detected by immunoprecipitation and immunoblotting. INa was measured by patch clamp with/without SUMO1 overexpression in HEK293 cells expressing wild-type (WT) or K442R-NaV1.5 and in neonatal rat cardiac myocytes (NRCMs). SUMOylation effects were studied in vivo by electrocardiograms and ambulatory telemetry using Scn5a heterozygous knockout (SCN5A+/-) mice and the de-SUMOylating protein SENP2 (AAV9-SENP2), AAV9-SUMO1, or the SUMOylation inhibitor anacardic acid. NaV1.5 trafficking was detected by immunofluorescence. RESULTS NaV1.5 was SUMOylated in HEK293 cells, NRCMs, and human heart tissue. HyperSUMOylation at NaV1.5-K442 increased INa in NRCMs and in HEK cells overexpressing WT but not K442R-Nav1.5. SUMOylation did not alter other channel properties including INa,L. AAV9-SENP2 or anacardic acid decreased INa, prolonged QRS duration, and produced heart block and arrhythmias in SCN5A+/- mice, whereas AAV9-SUMO1 increased INa and shortened QRS duration. SUMO1 overexpression enhanced membrane localization of NaV1.5. CONCLUSION SUMOylation of K442-Nav1.5 increases peak INa without changing INa,L, at least in part by altering membrane abundance. Our findings do not support SUMOylation as a mechanism for changes in INa,L. Nav1.5 SUMOylation may modify arrhythmic risk in disease states and represents a potential target for pharmacologic manipulation.
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Affiliation(s)
- Jin-Young Yoon
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Alexander M Greiner
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Julia S Jacobs
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Young-Rae Kim
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Tyler P Rasmussen
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - William J Kutschke
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Daniel S Matasic
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa
| | - Ajit Vikram
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Ravinder R Gaddam
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Haider Mehdi
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Kaikobad Irani
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa; Fraternal Order of Eagles Diabetes Research Center, Pappajohn Biomedical Institute, and Heart and Vascular Center, University of Iowa, Iowa City, Iowa.
| | - Barry London
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa, Iowa City, Iowa; Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa.
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4
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Durço AO, Marques LP, Souza DS. Channels wars: return of the single-channel. J Physiol 2023; 601:3993-3994. [PMID: 37598297 DOI: 10.1113/jp285358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 08/10/2023] [Indexed: 08/21/2023] Open
Affiliation(s)
- Aimée Obolari Durço
- Health Science Graduate Program, Federal University of Sergipe, Aracaju, Brazil
- Department of Physiology, Federal University of Sergipe, Aracaju, Brazil
| | | | - Diego Santos Souza
- Department of Physiology, Federal University of Sergipe, Aracaju, Brazil
- Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil
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5
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Selimi Z, Rougier JS, Abriel H, Kucera JP. A detailed analysis of single-channel Na v 1.5 recordings does not reveal any cooperative gating. J Physiol 2023; 601:3847-3868. [PMID: 37470338 DOI: 10.1113/jp284861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/23/2023] [Indexed: 07/21/2023] Open
Abstract
Cardiac voltage-gated sodium (Na+ ) channels (Nav 1.5) are crucial for myocardial electrical excitation. Recent studies based on single-channel recordings have suggested that Na+ channels interact functionally and exhibit coupled gating. However, the analysis of such recordings frequently relies on manual interventions, which can lead to bias. Here, we developed an automated pipeline to de-trend and idealize single-channel currents, and assessed possible functional interactions in cell-attached patch clamp experiments in HEK293 cells expressing human Nav 1.5 channels as well as in adult mouse and rabbit ventricular cardiomyocytes. Our pipeline involved de-trending individual sweeps by linear optimization using a library of predefined functions, followed by digital filtering and baseline offset. Subsequently, the processed sweeps were idealized based on the idea that the ensemble average of the idealized current identified by thresholds between current levels reconstructs at best the ensemble average current from the de-trended sweeps. This reconstruction was achieved by non-linear optimization. To ascertain functional interactions, we examined the distribution of the numbers of open channels at every time point during the activation protocol and compared it to the distribution expected for independent channels. We also examined whether the channels tended to synchronize their openings and closings. However, we did not uncover any solid evidence of such interactions in our recordings. Rather, our results indicate that wild-type Nav 1.5 channels are independent entities or exhibit only very weak functional interactions that are probably irrelevant under physiological conditions. Nevertheless, our unbiased analysis will be important for further studies examining whether auxiliary proteins potentiate functional Na+ channel interactions. KEY POINTS: Nav 1.5 channels are critical for cardiac excitation. They are part of macromolecular interacting complexes, and it was previously suggested that two neighbouring channels may functionally interact and exhibit coupled gating. Manual interventions when processing single-channel recordings can lead to bias and inaccurate data interpretation. We developed an automated pipeline to de-trend and idealize single-channel currents and assessed possible functional interactions between Nav 1.5 channels in HEK293 cells and cardiomyocytes during activation protocols using the cell-attached patch clamp technique. In recordings consisting of up to 1000 sweeps from the same patch, our analysis did not reveal any evidence of functional interactions or coupled gating between wild-type Nav 1.5 channels. Our unbiased analysis may be useful in further studies examining how Na+ channel interactions are affected by mutations and auxiliary proteins.
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Affiliation(s)
- Zoja Selimi
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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6
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Salvage SC, Jeevaratnam K, Huang CL, Jackson AP. Cardiac sodium channel complexes and arrhythmia: structural and functional roles of the β1 and β3 subunits. J Physiol 2023; 601:923-940. [PMID: 36354758 PMCID: PMC10953345 DOI: 10.1113/jp283085] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
In cardiac myocytes, the voltage-gated sodium channel NaV 1.5 opens in response to membrane depolarisation and initiates the action potential. The NaV 1.5 channel is typically associated with regulatory β-subunits that modify gating and trafficking behaviour. These β-subunits contain a single extracellular immunoglobulin (Ig) domain, a single transmembrane α-helix and an intracellular region. Here we focus on the role of the β1 and β3 subunits in regulating NaV 1.5. We catalogue β1 and β3 domain specific mutations that have been associated with inherited cardiac arrhythmia, including Brugada syndrome, long QT syndrome, atrial fibrillation and sudden death. We discuss how new structural insights into these proteins raises new questions about physiological function.
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Affiliation(s)
| | | | - Christopher L.‐H. Huang
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Department of PhysiologyDevelopment and NeuroscienceUniversity of CambridgeCambridgeUK
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7
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Hu CC, Wei X, Liu JM, Han LL, Xia CK, Wu J, You T, Zhu AF, Yao SL, Yuan SY, Xu HD, Xia ZY, Wang TT, Mao WK. Cardiac-targeted PIASy gene silencing mediates deSUMOylation of caveolin-3 and prevents ischemia/reperfusion-induced Na v1.5 downregulation and ventricular arrhythmias. Mil Med Res 2022; 9:58. [PMID: 36229865 PMCID: PMC9563440 DOI: 10.1186/s40779-022-00415-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 09/07/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Abnormal myocardial Nav1.5 expression and function cause lethal ventricular arrhythmias during myocardial ischemia-reperfusion (I/R). Protein inhibitor of activated STAT Y (PIASy)-mediated caveolin-3 (Cav-3) SUMO modification affects Cav-3 binding to the voltage-gated sodium channel 1.5 (Nav1.5). PIASy activity is increased after myocardial I/R, but it is unclear whether this is attributable to plasma membrane Nav1.5 downregulation and ventricular arrhythmias. METHODS Using recombinant adeno-associated virus subtype 9 (AAV9), rat cardiac PIASy was silenced using intraventricular injection of PIASy short hairpin RNA (shRNA). After two weeks, rat hearts were subjected to I/R and electrocardiography was performed to assess malignant arrhythmias. Tissues from peri-infarct areas of the left ventricle were collected for molecular biological measurements. RESULTS PIASy was upregulated by I/R (P < 0.01), with increased SUMO2/3 modification of Cav-3 and reduced membrane Nav1.5 density (P < 0.01). AAV9-PIASy shRNA intraventricular injection into the rat heart downregulated PIASy after I/R, at both mRNA and protein levels (P < 0.05 vs. Scramble-shRNA + I/R group), decreased SUMO-modified Cav-3 levels, enhanced Cav-3 binding to Nav1.5, and prevented I/R-induced decrease of Nav1.5 and Cav-3 co-localization in the intercalated disc and lateral membrane. PIASy silencing in rat hearts reduced I/R-induced fatal arrhythmias, which was reflected by a modest decrease in the duration of ventricular fibrillation (VF; P < 0.05 vs. Scramble-shRNA + I/R group) and a significantly reduced arrhythmia score (P < 0.01 vs. Scramble-shRNA + I/R group). The anti-arrhythmic effects of PIASy silencing were also evidenced by decreased episodes of ventricular tachycardia (VT), sustained VT and VF, especially at the time 5-10 min after ischemia (P < 0.05 vs. Scramble-shRNA + IR group). Using in vitro human embryonic kidney 293 T (HEK293T) cells and isolated adult rat cardiomyocyte models exposed to hypoxia/reoxygenation (H/R), we confirmed that increased PIASy promoted Cav-3 modification by SUMO2/3 and Nav1.5/Cav-3 dissociation after H/R. Mutation of SUMO consensus lysine sites in Cav-3 (K38R or K144R) altered the membrane expression levels of Nav1.5 and Cav-3 before and after H/R in HEK293T cells. CONCLUSIONS I/R-induced cardiac PIASy activation increased Cav-3 SUMOylation by SUMO2/3 and dysregulated Nav1.5-related ventricular arrhythmias. Cardiac-targeted PIASy silencing mediated Cav-3 deSUMOylation and partially prevented I/R-induced Nav1.5 downregulation in the plasma membrane of cardiomyocytes, and subsequent ventricular arrhythmias in rats. PIASy was identified as a potential therapeutic target for life-threatening arrhythmias in patients with ischemic heart diseases.
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Affiliation(s)
- Chen-Chen Hu
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xin Wei
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jin-Min Liu
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Lin-Lin Han
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Cheng-Kun Xia
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Jing Wu
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Tao You
- Department of Cardiology, the Second Affiliated Hospital of Soochow University, Suzhou, 215004, Jiangsu, China
| | - A-Fang Zhu
- Department of Anesthesiology, Peking Union Medical College Hospital, CAMS and PUMC, Beijing, 100730, China
| | - Shang-Long Yao
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Shi-Ying Yuan
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Hao-Dong Xu
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Zheng-Yuan Xia
- State Key Laboratory of Pharmaceutical Biotechnology, the University of Hong Kong, Hong Kong, 999077, China.,Department of Anesthesiology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524000, Guangdong, China
| | - Ting-Ting Wang
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Wei-Ke Mao
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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8
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Wu X, Li Y, Hong L. Effects of Mexiletine on a Race-specific Mutation in Nav1.5 Associated With Long QT Syndrome. Front Physiol 2022; 13:904664. [PMID: 35864896 PMCID: PMC9294368 DOI: 10.3389/fphys.2022.904664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.5 plays an essential role in the generation and propagation of action potential in cardiomyocytes. Mutations in Nav1.5 have been associated with LQT syndrome, Brugada syndrome, and sudden arrhythmia death syndrome. Genetic studies showed that Nav1.5 mutations vary across race-ethnic groups. Here we investigated an Asian-specific mutation Nav1.5-P1090L associated with LQT syndrome. We found that Nav1.5-P1090L mutation perturbed the sodium channel function. It altered the gating process of the channel and exhibited an enhanced window current. Treatment with mexiletine reversed the depolarization shift of the steady-state inactivation produced by P1090L. Mexiletine also modified the recovery from steady-state inactivation and the development of inactivation of P1090L. It rescued the dysfunctional inactivation of P1090L and reduced the P1090L channel’s availability.
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Affiliation(s)
- Xin Wu
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Yawei Li
- Department of Preventive Medicine, Northwestern University, Chicago, IL, United States
| | - Liang Hong
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- *Correspondence: Liang Hong,
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9
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Anderson CL, Munawar S, Reilly L, Kamp TJ, January CT, Delisle BP, Eckhardt LL. How Functional Genomics Can Keep Pace With VUS Identification. Front Cardiovasc Med 2022; 9:900431. [PMID: 35859585 PMCID: PMC9291992 DOI: 10.3389/fcvm.2022.900431] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 06/09/2022] [Indexed: 01/03/2023] Open
Abstract
Over the last two decades, an exponentially expanding number of genetic variants have been identified associated with inherited cardiac conditions. These tremendous gains also present challenges in deciphering the clinical relevance of unclassified variants or variants of uncertain significance (VUS). This review provides an overview of the advancements (and challenges) in functional and computational approaches to characterize variants and help keep pace with VUS identification related to inherited heart diseases.
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Affiliation(s)
- Corey L. Anderson
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Saba Munawar
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Louise Reilly
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Timothy J. Kamp
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Craig T. January
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
| | - Brian P. Delisle
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Lee L. Eckhardt
- Cellular and Molecular Arrythmias Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States
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Absolute Quantification of Nav1.5 Expression by Targeted Mass Spectrometry. Int J Mol Sci 2022; 23:ijms23084177. [PMID: 35456996 PMCID: PMC9028338 DOI: 10.3390/ijms23084177] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 11/20/2022] Open
Abstract
Nav1.5 is the pore forming α-subunit of the cardiac voltage-gated sodium channel that initiates cardiac action potential and regulates the human heartbeat. A normal level of Nav1.5 is crucial to cardiac function and health. Over- or under-expression of Nav1.5 can cause various cardiac diseases ranging from short PR intervals to Brugada syndromes. An assay that can directly quantify the protein amount in biological samples would be a priori to accurately diagnose and treat Nav1.5-associated cardiac diseases. Due to its large size (>200 KD), multipass transmembrane domains (24 transmembrane passes), and heavy modifications, Nav1.5 poses special quantitation challenges. To date, only the relative quantities of this protein have been measured in biological samples. Here, we describe the first targeted and mass spectrometry (MS)-based quantitative assay that can provide the copy numbers of Nav1.5 in cells with a well-defined lower limit of quantification (LLOQ) and precision. Applying the developed assay, we successfully quantified transiently expressed Nav1.5 in as few as 1.5 million Chinese hamster ovary (CHO) cells. The obtained quantity was 3 ± 2 fmol on the column and 3 ± 2 × 104 copies/cell. To our knowledge, this is the first absolute quantity of Nav1.5 measured in a biological sample.
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11
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Horváth B, Szentandrássy N, Almássy J, Dienes C, Kovács ZM, Nánási PP, Banyasz T. Late Sodium Current of the Heart: Where Do We Stand and Where Are We Going? Pharmaceuticals (Basel) 2022; 15:ph15020231. [PMID: 35215342 PMCID: PMC8879921 DOI: 10.3390/ph15020231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 02/05/2023] Open
Abstract
Late sodium current has long been linked to dysrhythmia and contractile malfunction in the heart. Despite the increasing body of accumulating information on the subject, our understanding of its role in normal or pathologic states is not complete. Even though the role of late sodium current in shaping action potential under physiologic circumstances is debated, it’s unquestioned role in arrhythmogenesis keeps it in the focus of research. Transgenic mouse models and isoform-specific pharmacological tools have proved useful in understanding the mechanism of late sodium current in health and disease. This review will outline the mechanism and function of cardiac late sodium current with special focus on the recent advances of the area.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Norbert Szentandrássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Csaba Dienes
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Zsigmond Máté Kovács
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Péter P. Nánási
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Dental Physiology and Pharmacology, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Correspondence: ; Tel.: +36-(52)-255-575; Fax: +36-(52)-255-116
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Daimi H, Lozano-Velasco E, Aranega A, Franco D. Genomic and Non-Genomic Regulatory Mechanisms of the Cardiac Sodium Channel in Cardiac Arrhythmias. Int J Mol Sci 2022; 23:1381. [PMID: 35163304 PMCID: PMC8835759 DOI: 10.3390/ijms23031381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/19/2022] Open
Abstract
Nav1.5 is the predominant cardiac sodium channel subtype, encoded by the SCN5A gene, which is involved in the initiation and conduction of action potentials throughout the heart. Along its biosynthesis process, Nav1.5 undergoes strict genomic and non-genomic regulatory and quality control steps that allow only newly synthesized channels to reach their final membrane destination and carry out their electrophysiological role. These regulatory pathways are ensured by distinct interacting proteins that accompany the nascent Nav1.5 protein along with different subcellular organelles. Defects on a large number of these pathways have a tremendous impact on Nav1.5 functionality and are thus intimately linked to cardiac arrhythmias. In the present review, we provide current state-of-the-art information on the molecular events that regulate SCN5A/Nav1.5 and the cardiac channelopathies associated with defects in these pathways.
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Affiliation(s)
- Houria Daimi
- Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
| | - Estefanía Lozano-Velasco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Amelia Aranega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
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13
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Xiong H, Bai X, Quan Z, Yu D, Zhang H, Zhang C, Liang L, Yao Y, Yang Q, Wang Z, Wang L, Huang Y, Li H, Ren X, Tu X, Ke T, Xu C, Wang QK. Mechanistic insights into the interaction of cardiac sodium channel Na v1.5 with MOG1 and a new molecular mechanism for Brugada syndrome. Heart Rhythm 2021; 19:478-489. [PMID: 34843967 DOI: 10.1016/j.hrthm.2021.11.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 11/14/2021] [Accepted: 11/20/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations in cardiac sodium channel Nav1.5 cause Brugada syndrome (BrS). MOG1 is a chaperone that binds to Nav1.5, facilitates Nav1.5 trafficking to the cell surface, and enhances the amplitude of sodium current INa. OBJECTIVE The purpose of this study was to identify structural elements involved in MOG1-Nav1.5 interaction and their relevance to the pathogenesis of BrS. METHODS Systematic analyses of large deletions, microdeletions, and point mutations, and glutathione S-transferases pull-down, co-immunoprecipitation, cell surface protein quantification, and patch-clamping of INa were performed. RESULTS Large deletion analysis defined the MOG1-Nav1.5 interaction domain to amino acids S476-H585 of Nav1.5 Loop I connecting transmembrane domains I and II. Microdeletion and point mutation analyses further defined the domain to F530T531F532R533R534R535. Mutations F530A, F532A, R533A, and R534A, but not T531A and R535A, significantly reduced MOG1-Nav1.5 interaction and eliminated MOG1-enhanced INa. Mutagenesis analysis identified D24, E36, D44, E53, and E101A of MOG1 as critical residues for interaction with Nav1.5 Loop I. We then characterized 3 mutations at the MOG1-Nav1.5 interaction domain: p.F530V, p.F532C, and p.R535Q reported from patients with long QT syndrome and BrS. We found that p.F532C reduced MOG1-Nav1.5 interaction and eliminated MOG1 function on INa; p.R535Q is also a loss-of-function mutation that reduces INa amplitude in a MOG1-independent manner, whereas p.F530V is benign as it does not have an apparent effect on MOG1 and INa. CONCLUSION Our findings define the MOG1-Nav1.5 interaction domain to a 5-amino-acid motif of F530T531F532R533R534 in Loop I. Mutation p.F532C associated with BrS abolishes Nav1.5 interaction with MOG1 and reduces MOG1-enhanced INa density, thereby uncovering a novel molecular mechanism for the pathogenesis of BrS.
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Affiliation(s)
- Hongbo Xiong
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Xuemei Bai
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Zhuang Quan
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Dong Yu
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Hongfu Zhang
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Chi Zhang
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Lina Liang
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Yufeng Yao
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Qin Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Schoolof Medicine, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Zhijie Wang
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Longfei Wang
- Henan Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Zhengzhou, P. R. China
| | - Yuan Huang
- National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, P. R. China
| | - Hui Li
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Xiang Ren
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Xin Tu
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China
| | - Tie Ke
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China.
| | - Chengqi Xu
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China.
| | - Qing K Wang
- Center for Human Genome Research, Department of Biological Sciences, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Wuhan, P. R. China.
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Specific Deletion of the FHA Domain Containing SLMAP3 Isoform in Postnatal Myocardium Has No Impact on Structure or Function. CARDIOGENETICS 2021. [DOI: 10.3390/cardiogenetics11040018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Sarcolemmal membrane-associated proteins (SLMAPs) belong to the superfamily of tail-anchored membrane proteins known to regulate diverse biological processes, including protein trafficking and signal transduction. Mutations in SLMAP have been linked to Brugada and defective sodium channel Nav1.5 shuttling. The SLMAP gene is alternatively spliced to generate numerous isoforms, broadly defined as SLMAP1 (~35 kDa), SLMAP2 (~45 kDa) and SLMAP3 (~80–95 kDa), which are highly expressed in the myocardium. The SLMAP3 isoform exhibits ubiquitous expression carrying an FHA domain and is believed to negatively regulate Hippo signaling to dictate cell growth/death and differentiation. Using the αMHC-MerCreMer-flox system to target the SLMAP gene, we specifically deleted the SLMAP3 isoform in postnatal mouse hearts without any changes in the expression of SLMAP1/SLMAP2 isoforms. The in vivo analysis of mice with SLMAP3 cardiac deficiency revealed no significant changes to heart structure or function in young or aged mice without or with isoproterenol-induced stress. SLMAP3-deficient hearts revealed no obvious differences in cardiac size, function or hypertrophic response. Further, the molecular analysis indicated that SLMAP3 loss had a minor impact on sodium channel (Nav1.5) expression without affecting cardiac electrophysiology in postnatal myocardium. Surprisingly, the loss of SLMAP3 did not impact Hippo signaling in postnatal myocardium. We conclude that the FHA domain-containing SLMAP3 isoform has no impact on Hippo signaling or sodium channels in postnatal myocardium, which is able to function and respond normally to stress in its absence. Whether SLMAP1/SMAP2 isoforms can compensate for the loss of SLMAP3 in the affairs of the postnatal heart remains to be determined.
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15
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Wu X, Hong L. Calmodulin Interactions with Voltage-Gated Sodium Channels. Int J Mol Sci 2021; 22:ijms22189798. [PMID: 34575961 PMCID: PMC8472079 DOI: 10.3390/ijms22189798] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023] Open
Abstract
Calmodulin (CaM) is a small protein that acts as a ubiquitous signal transducer and regulates neuronal plasticity, muscle contraction, and immune response. It interacts with ion channels and plays regulatory roles in cellular electrophysiology. CaM modulates the voltage-gated sodium channel gating process, alters sodium current density, and regulates sodium channel protein trafficking and expression. Many mutations in the CaM-binding IQ domain give rise to diseases including epilepsy, autism, and arrhythmias by interfering with CaM interaction with the channel. In the present review, we discuss CaM interactions with the voltage-gated sodium channel and modulators involved in CaM regulation, as well as summarize CaM-binding IQ domain mutations associated with human diseases in the voltage-gated sodium channel family.
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16
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Nerbonne JM. Controlling the Traffic to Keep the Beat: Targeting of Myocardial Sodium Channels. Circ Res 2021; 129:366-368. [PMID: 34292782 DOI: 10.1161/circresaha.121.319653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jeanne M Nerbonne
- Center for Cardiovascular Research, Cardiovascular Division, Department of Medicine, Washington University Medical School, St. Louis, MO
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17
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Kabakov AY, Sengun E, Lu Y, Roder K, Bronk P, Baggett B, Turan NN, Moshal KS, Koren G. Three-Week-Old Rabbit Ventricular Cardiomyocytes as a Novel System to Study Cardiac Excitation and EC Coupling. Front Physiol 2021; 12:672360. [PMID: 34867432 PMCID: PMC8637404 DOI: 10.3389/fphys.2021.672360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 10/06/2021] [Indexed: 01/14/2023] Open
Abstract
Cardiac arrhythmias significantly contribute to cardiovascular morbidity and mortality. The rabbit heart serves as an accepted model system for studying cardiac cell excitation and arrhythmogenicity. Accordingly, primary cultures of adult rabbit ventricular cardiomyocytes serve as a preferable model to study molecular mechanisms of human cardiac excitation. However, the use of adult rabbit cardiomyocytes is often regarded as excessively costly. Therefore, we developed and characterized a novel low-cost rabbit cardiomyocyte model, namely, 3-week-old ventricular cardiomyocytes (3wRbCMs). Ventricular myocytes were isolated from whole ventricles of 3-week-old New Zealand White rabbits of both sexes by standard enzymatic techniques. Using wheat germ agglutinin, we found a clear T-tubule structure in acutely isolated 3wRbCMs. Cells were adenovirally infected (multiplicity of infection of 10) to express Green Fluorescent Protein (GFP) and cultured for 48 h. The cells showed action potential duration (APD90 = 253 ± 24 ms) and calcium transients similar to adult rabbit cardiomyocytes. Freshly isolated and 48-h-old-cultured cells expressed critical ion channel proteins: calcium voltage-gated channel subunit alpha1 C (Cavα1c), sodium voltage-gated channel alpha subunit 5 (Nav1.5), potassium voltage-gated channel subfamily D member 3 (Kv4.3), and subfamily A member 4 (Kv1.4), and also subfamily H member 2 (RERG. Kv11.1), KvLQT1 (K7.1) protein and inward-rectifier potassium channel (Kir2.1). The cells displayed an appropriate electrophysiological phenotype, including fast sodium current (I Na), transient outward potassium current (I to), L-type calcium channel peak current (I Ca,L), rapid and slow components of the delayed rectifier potassium current (I Kr and I Ks), and inward rectifier (I K1). Although expression of the channel proteins and some currents decreased during the 48 h of culturing, we conclude that 3wRbCMs are a new, low-cost alternative to the adult-rabbit-cardiomyocytes system, which allows the investigation of molecular mechanisms of cardiac excitation on morphological, biochemical, genetic, physiological, and biophysical levels.
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Affiliation(s)
- Anatoli Y Kabakov
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Elif Sengun
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Department of Pharmacology, Institute of Graduate Studies in Health Sciences, Istanbul University, Istanbul, Türkiye
| | - Yichun Lu
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Karim Roder
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Peter Bronk
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Brett Baggett
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Nilüfer N Turan
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Karni S Moshal
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - Gideon Koren
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI, United States
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