1
|
Hartmann N, Knierim M, Maurer W, Dybkova N, Zeman F, Hasenfuß G, Sossalla S, Streckfuss-Bömeke K. Na V1.8 as Proarrhythmic Target in a Ventricular Cardiac Stem Cell Model. Int J Mol Sci 2024; 25:6144. [PMID: 38892333 PMCID: PMC11172914 DOI: 10.3390/ijms25116144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 05/25/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024] Open
Abstract
The sodium channel NaV1.8, encoded by the SCN10A gene, has recently emerged as a potential regulator of cardiac electrophysiology. We have previously shown that NaV1.8 contributes to arrhythmogenesis by inducing a persistent Na+ current (late Na+ current, INaL) in human atrial and ventricular cardiomyocytes (CM). We now aim to further investigate the contribution of NaV1.8 to human ventricular arrhythmogenesis at the CM-specific level using pharmacological inhibition as well as a genetic knockout (KO) of SCN10A in induced pluripotent stem cell CM (iPSC-CM). In functional voltage-clamp experiments, we demonstrate that INaL was significantly reduced in ventricular SCN10A-KO iPSC-CM and in control CM after a specific pharmacological inhibition of NaV1.8. In contrast, we did not find any effects on ventricular APD90. The frequency of spontaneous sarcoplasmic reticulum Ca2+ sparks and waves were reduced in SCN10A-KO iPSC-CM and control cells following the pharmacological inhibition of NaV1.8. We further analyzed potential triggers of arrhythmias and found reduced delayed afterdepolarizations (DAD) in SCN10A-KO iPSC-CM and after the specific inhibition of NaV1.8 in control cells. In conclusion, we show that NaV1.8-induced INaL primarily impacts arrhythmogenesis at a subcellular level, with minimal effects on systolic cellular Ca2+ release. The inhibition or knockout of NaV1.8 diminishes proarrhythmic triggers in ventricular CM. In conjunction with our previously published results, this work confirms NaV1.8 as a proarrhythmic target that may be useful in an anti-arrhythmic therapeutic strategy.
Collapse
Affiliation(s)
- Nico Hartmann
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
| | - Maria Knierim
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
- Clinic for Cardio-Thoracic and Vascular Surgery, University Medical Center, 37075 Göttingen, Germany
| | - Wiebke Maurer
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
| | - Nataliya Dybkova
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
| | - Florian Zeman
- Center for Clinicial Trials, University of Regensburg, 93042 Regensburg, Germany
| | - Gerd Hasenfuß
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
| | - Samuel Sossalla
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
- Medical Clinic I, Cardiology and Angiology, Giessen and Department of Cardiology at Kerckhoff Heart and Lung Center, Justus-Liebig-University, 61231 Bad Nauheim, Germany
| | - Katrin Streckfuss-Bömeke
- Clinic for Cardiology and Pneumology, University Medical Center, 37075 Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen and Rhein Main, 61231 Bad Nauheim, Germany
- Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany
| |
Collapse
|
2
|
Liutkute A, Prosser BL, Voigt N. Microtubules: highway to … arrhythmia? Cardiovasc Res 2024; 120:671-672. [PMID: 38637305 DOI: 10.1093/cvr/cvae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 04/20/2024] Open
Affiliation(s)
- Aiste Liutkute
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
- Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), University of Göttingen, Germany
| | - Benjamin L Prosser
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
- Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), University of Göttingen, Germany
| |
Collapse
|
3
|
Thompson AC, Aizenman CD. Characterization of Na + currents regulating intrinsic excitability of optic tectal neurons. Life Sci Alliance 2024; 7:e202302232. [PMID: 37918964 PMCID: PMC10622587 DOI: 10.26508/lsa.202302232] [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: 06/22/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023] Open
Abstract
Developing neurons adapt their intrinsic excitability to maintain stable output despite changing synaptic input. The mechanisms behind this process remain unclear. In this study, we examined Xenopus optic tectal neurons and found that the expressions of Nav1.1 and Nav1.6 voltage-gated Na+ channels are regulated during changes in intrinsic excitability, both during development and becsuse of changes in visual experience. Using whole-cell electrophysiology, we demonstrate the existence of distinct, fast, persistent, and resurgent Na+ currents in the tectum, and show that these Na+ currents are co-regulated with changes in Nav channel expression. Using antisense RNA to suppress the expression of specific Nav subunits, we found that up-regulation of Nav1.6 expression, but not Nav1.1, was necessary for experience-dependent increases in Na+ currents and intrinsic excitability. Furthermore, this regulation was also necessary for normal development of sensory guided behaviors. These data suggest that the regulation of Na+ currents through the modulation of Nav1.6 expression, and to a lesser extent Nav1.1, plays a crucial role in controlling the intrinsic excitability of tectal neurons and guiding normal development of the tectal circuitry.
Collapse
Affiliation(s)
- Adrian C Thompson
- https://ror.org/05gq02987 Department of Neuroscience, Brown University, Providence, RI, USA
| | - Carlos D Aizenman
- https://ror.org/05gq02987 Department of Neuroscience, Brown University, Providence, RI, USA
| |
Collapse
|
4
|
Liu H, Fan W, Fan B. Necroptosis in apical periodontitis: A programmed cell death with multiple roles. J Cell Physiol 2023; 238:1964-1981. [PMID: 37431828 DOI: 10.1002/jcp.31073] [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: 05/10/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/12/2023]
Abstract
Programmed cell death (PCD) has been a research focus for decades and different mechanisms of cell death, such as necroptosis, pyroptosis, ferroptosis, and cuproptosis have been discovered. Necroptosis, a form of inflammatory PCD, has gained increasing attention in recent years due to its critical role in disease progression and development. Unlike apoptosis, which is mediated by caspases and characterized by cell shrinkage and membrane blebbing, necroptosis is mediated by mixed lineage kinase domain-like protein (MLKL) and characterized by cell enlargement and plasma membrane rupture. Necroptosis can be triggered by bacterial infection, which on the one hand represents a host defense mechanism against the infection, but on the other hand can facilitate bacterial escape and worsen inflammation. Despite its importance in various diseases, a comprehensive review on the involvement and roles of necroptosis in apical periodontitis is still lacking. In this review, we tried to provide an overview of recent progresses in necroptosis research, summarized the pathways involved in apical periodontitis (AP) activation, and discussed how bacterial pathogens induce and regulated necroptosis and how necroptosis would inhibit bacteria. Furthermore, the interplay between various types of cell death in AP and the potential treatment strategy for AP by targeting necroptosis were also discussed.
Collapse
Affiliation(s)
- Hui Liu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Wei Fan
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Bing Fan
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| |
Collapse
|
5
|
Lu A, Gu R, Chu C, Xia Y, Wang J, Davis DR, Liang W. Inhibition of Wnt/β-catenin signaling upregulates Na v 1.5 channels in Brugada syndrome iPSC-derived cardiomyocytes. Physiol Rep 2023; 11:e15696. [PMID: 37226398 PMCID: PMC10209518 DOI: 10.14814/phy2.15696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 04/26/2023] [Accepted: 04/26/2023] [Indexed: 05/26/2023] Open
Abstract
The voltage-gated Nav 1.5 channels mediate the fast Na+ current (INa ) in cardiomyocytes initiating action potentials and cardiac contraction. Downregulation of INa , as occurs in Brugada syndrome (BrS), causes ventricular arrhythmias. The present study investigated whether the Wnt/β-catenin signaling regulates Nav 1.5 in human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). In healthy male and female iPSC-CMs, activation of Wnt/β-catenin signaling by CHIR-99021 reduced (p < 0.01) both Nav 1.5 protein and SCN5A mRNA. In iPSC-CMs from a BrS patient, both Nav 1.5 protein and peak INa were reduced compared to those in healthy iPSC-CMs. Treatment of BrS iPSC-CMs with Wnt-C59, a small-molecule Wnt inhibitor, led to a 2.1-fold increase in Nav 1.5 protein (p = 0.0005) but surprisingly did not affect SCN5A mRNA (p = 0.146). Similarly, inhibition of Wnt signaling using shRNA-mediated β-catenin knockdown in BrS iPSC-CMs led to a 4.0-fold increase in Nav 1.5, which was associated with a 4.9-fold increase in peak INa but only a 2.1-fold increase in SCN5A mRNA. The upregulation of Nav 1.5 by β-catenin knockdown was verified in iPSC-CMs from a second BrS patient. This study demonstrated that Wnt/β-catenin signaling inhibits Nav 1.5 expression in both male and female human iPSC-CMs, and inhibition of Wnt/β-catenin signaling upregulates Nav 1.5 in BrS iPSC-CMs through both transcriptional and posttranscriptional mechanisms.
Collapse
Affiliation(s)
- Aizhu Lu
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| | - Ruonan Gu
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
- Department of Anesthesiology, Zhujiang HospitalSouthern Medical UniversityGuangzhouChina
| | - Cencen Chu
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| | - Ying Xia
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| | - Jerry Wang
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| | - Darryl R. Davis
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| | - Wenbin Liang
- University of Ottawa Heart InstituteOttawaOntarioCanada
- Department of Cellular and Molecular MedicineUniversity of OttawaOttawaOntarioCanada
| |
Collapse
|
6
|
Spinal cord injury-mediated changes in electrophysiological properties of rat gastric nodose ganglion neurons. Exp Neurol 2022; 348:113927. [PMID: 34798136 PMCID: PMC8727501 DOI: 10.1016/j.expneurol.2021.113927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 10/30/2021] [Accepted: 11/11/2021] [Indexed: 02/03/2023]
Abstract
In preclinical rodent models, spinal cord injury (SCI) manifests as gastric vagal afferent dysfunction both acutely and chronically. However, the mechanism that underlies this dysfunction remains unknown. In the current study, we examined the effect of SCI on gastric nodose ganglia (NG) neuron excitability and on voltage-gated Na+ (NaV) channels expression and function in rats after an acute (i.e. 3-days) and chronic (i.e. 3-weeks) period. Rats randomly received either T3-SCI or sham control surgery 3-days or 3-weeks prior to experimentation as well as injections of 3% DiI solution into the stomach to identify gastric NG neurons. Single cell qRT-PCR was performed on acutely dissociated DiI-labeled NG neurons to measure NaV1.7, NaV1.8 and NaV1.9 expression levels. The results indicate that all 3 channel subtypes decreased. Current- and voltage-clamp whole-cell patch-clamp recordings were performed on acutely dissociated DiI-labeled NG neurons to measure active and passive properties of C- and A-fibers as well as the biophysical characteristics of NaV1.8 channels in gastric NG neurons. Acute and chronic SCI did not demonstrate deleterious effects on either passive properties of dissociated gastric NG neurons or biophysical properties of NaV1.8. These findings suggest that although NaV gene expression levels change following SCI, NaV1.8 function is not altered. The disruption throughout the entirety of the vagal afferent neuron has yet to be investigated.
Collapse
|
7
|
Role of ranolazine in heart failure: From cellular to clinic perspective. Eur J Pharmacol 2022; 919:174787. [PMID: 35114190 DOI: 10.1016/j.ejphar.2022.174787] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/25/2021] [Accepted: 01/25/2022] [Indexed: 12/17/2022]
Abstract
Ranolazine was approved by the US Food and Drug Administration as an antianginal drug in 2006, and has been used since in certain groups of patients with stable angina. The therapeutic action of ranolazine was initially attributed to inhibitory effects on fatty acids metabolism. As investigations went on, however, it developed that the main beneficial effects of ranolazine arise from its action on the late sodium current in the heart. Since late sodium currents were discovered to be involved in various heart pathologies such as ischemia, arrhythmias, systolic and diastolic dysfunctions, and all these conditions are associated with heart failure, ranolazine has in some way been tested either directly or indirectly on heart failure in numerous experimental and clinical studies. As the heart continuously remodels following any sort of severe injury, the inhibition by ranolazine of the underlying mechanisms of cardiac remodeling including ion disturbances, oxidative stress, inflammation, apoptosis, fibrosis, metabolic dysregulation, and neurohormonal impairment are discussed, along with unresolved issues. A projection of pathologies targeted by ranolazine from cellular level to clinical is provided in this review.
Collapse
|
8
|
Li J, Richmond B, Hong T. Cardiac T-Tubule cBIN1-Microdomain, a Diagnostic Marker and Therapeutic Target of Heart Failure. Int J Mol Sci 2021; 22:ijms22052299. [PMID: 33669042 PMCID: PMC7956774 DOI: 10.3390/ijms22052299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/19/2021] [Accepted: 02/22/2021] [Indexed: 12/23/2022] Open
Abstract
Since its first identification as a cardiac transverse tubule (t-tubule) protein, followed by the cloning of the cardiac isoform responsible for t-tubule membrane microdomain formation, cardiac bridging integrator 1 (cBIN1) and its organized microdomains have emerged as a key mechanism in maintaining normal beat-to-beat heart contraction and relaxation. The abnormal remodeling of cBIN1-microdomains occurs in stressed and diseased cardiomyocytes, contributing to the pathophysiology of heart failure. Due to the homeostatic turnover of t-tubule cBIN1-microdomains via microvesicle release into the peripheral circulation, plasma cBIN1 can be assayed as a liquid biopsy of cardiomyocyte health. A new blood test cBIN1 score (CS) has been developed as a dimensionless inverse index derived from plasma cBIN1 concentration with a diagnostic and prognostic power for clinical outcomes in stable ambulatory patients with heart failure with reduced or preserved ejection fraction (HFrEF or HFpEF). Recent evidence further indicates that exogenous cBIN1 introduced by adeno-associated virus 9-based gene therapy can rescue cardiac contraction and relaxation in failing hearts. The therapeutic potential of cBIN1 gene therapy is enormous given its ability to rescue cardiac inotropy and provide lusitropic protection in the meantime. These unprecedented capabilities of cBIN1 gene therapy are shifting the current paradigm of therapy development for heart failure, particularly HFpEF.
Collapse
Affiliation(s)
- Jing Li
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (B.R.)
| | - Bradley Richmond
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (B.R.)
| | - TingTing Hong
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (B.R.)
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT 84112, USA
- Correspondence: ; Tel.: +1-801-581-3090
| |
Collapse
|
9
|
Abstract
Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. The availability of therapy for this lethal disease emphasizes the importance of early and accurate diagnosis. Additionally, understanding of the molecular mechanisms underlying LQTS could help to optimize genotype-specific treatments to prevent deaths in LQTS patients. In this review, we briefly summarize current knowledge regarding molecular underpinning of LQTS, in particular focusing on LQT1, LQT2, and LQT3, and discuss novel strategies to study ion channel dysfunction and drug-specific therapies in LQT1, LQT2, and LQT3 syndromes.
Collapse
Affiliation(s)
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
| |
Collapse
|
10
|
Li L, Tong A, Zhang Q, Wei Y, Wei X. The molecular mechanisms of MLKL-dependent and MLKL-independent necrosis. J Mol Cell Biol 2020; 13:3-14. [PMID: 33064829 PMCID: PMC8035999 DOI: 10.1093/jmcb/mjaa055] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 07/27/2020] [Accepted: 08/14/2020] [Indexed: 02/05/2023] Open
Abstract
Necrosis, a type of unwanted and passive cell demise, usually occurs under the excessive external stress and is considered to be unregulated. However, under some special conditions such as caspase inhibition, necrosis is regulable in a well-orchestrated way. The term 'regulated necrosis' has been proposed to describe such programed necrosis. Recently, several forms of necrosis, including necroptosis, pyroptosis, ferroptosis, parthanatos, oxytosis, NETosis, and Na+/K+-ATPase-mediated necrosis, have been identified, and some crucial regulators governing regulated necrosis have also been discovered. Mixed lineage kinase domain-like pseudokinase (MLKL), a core regulator in necroptosis, acts as an executioner in response to ligands of death receptor family. Its activation requires the receptor-interacting protein kinases, RIP1 and RIP3. However, MLKL is only involved in necroptosis, i.e. MLKL is dispensable for necrosis. Therefore, this review is aimed at summarizing the molecular mechanisms of MLKL-dependent and MLKL-independent necrosis.
Collapse
Affiliation(s)
- Lu Li
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - An Tong
- Department of Gynecology and Obstetrics, Development and Related Disease of Women and Children Key Laboratory of Sichuan Province, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second Hospital, and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Qiangsheng Zhang
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yuquan Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Xiawei Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| |
Collapse
|
11
|
Ovics P, Regev D, Baskin P, Davidor M, Shemer Y, Neeman S, Ben-Haim Y, Binah O. Drug Development and the Use of Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Disease Modeling and Drug Toxicity Screening. Int J Mol Sci 2020; 21:E7320. [PMID: 33023024 PMCID: PMC7582587 DOI: 10.3390/ijms21197320] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/23/2020] [Accepted: 09/27/2020] [Indexed: 12/19/2022] Open
Abstract
: Over the years, numerous groups have employed human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) as a superb human-compatible model for investigating the function and dysfunction of cardiomyocytes, drug screening and toxicity, disease modeling and for the development of novel drugs for heart diseases. In this review, we discuss the broad use of iPSC-CMs for drug development and disease modeling, in two related themes. In the first theme-drug development, adverse drug reactions, mechanisms of cardiotoxicity and the need for efficient drug screening protocols-we discuss the critical need to screen old and new drugs, the process of drug development, marketing and Adverse Drug reactions (ADRs), drug-induced cardiotoxicity, safety screening during drug development, drug development and patient-specific effect and different mechanisms of ADRs. In the second theme-using iPSC-CMs for disease modeling and developing novel drugs for heart diseases-we discuss the rationale for using iPSC-CMs and modeling acquired and inherited heart diseases with iPSC-CMs.
Collapse
Affiliation(s)
- Paz Ovics
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Danielle Regev
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Polina Baskin
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Mor Davidor
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Yuval Shemer
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Shunit Neeman
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| | - Yael Ben-Haim
- Institute of Molecular and Clinical Sciences, St. George’s University of London, London SW17 0RE, UK;
- Cardiology Clinical Academic Group, St. George’s University Hospitals NHS Foundation Trust, London SW17 0QT, UK
| | - Ofer Binah
- Department of Physiology, Biophysics and Systems Biology, The Rappaport Institute, Ruth & Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel; (P.O.); (D.R.); (P.B.); (M.D.); (Y.S.); (S.N.)
| |
Collapse
|
12
|
Risner ML, McGrady NR, Pasini S, Lambert WS, Calkins DJ. Elevated ocular pressure reduces voltage-gated sodium channel NaV1.2 protein expression in retinal ganglion cell axons. Exp Eye Res 2020; 190:107873. [PMID: 31734278 PMCID: PMC6957720 DOI: 10.1016/j.exer.2019.107873] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/16/2019] [Accepted: 11/13/2019] [Indexed: 01/05/2023]
Abstract
Glaucoma is an age-related neurodegenerative disease that is commonly associated with sensitivity to intraocular pressure. The disease selectively targets retinal ganglion cells (RGCs) and constituent axons. RGC axons are rich in voltage-gated sodium channels, which are essential for action potential initiation and regeneration. Here, we identified voltage-dependent sodium channel, NaV1.2, in the retina, examined how this channel contributes to RGC light responses, and monitored NaV1.2 mRNA and protein expression in the retina during progression of modeled glaucoma. We found NaV1.2 is predominately localized in ganglion cell intraretinal axons with dispersed expression in the outer and inner plexiform layers. We showed Phrixotoxin-3, a potent NaV1.2 channel blocker, significantly decreased RGC electrical activity in a dose-dependent manner with an IC50 of 40 nM. Finally, we found four weeks of raised intraocular pressure (30% above baseline) significantly increased NaV1.2 mRNA expression but reduced NaV1.2 protein level in the retina up to 57% (p < 0.001). Following prolonged intraocular pressure elevation, NaV1.2 protein expression particularly diminished at distal sections of ganglion cell intraretinal axons (p ≤ 0.01). Our results suggest NaV1.2 might be a therapeutic target during disease progression to maintain RGC excitability, preserving presynaptic connections through action potential backpropagation.
Collapse
Affiliation(s)
- Michael L Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA
| | - Nolan R McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA
| | - Silvia Pasini
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA
| | - Wendi S Lambert
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, 11435 Medical Research Building IV, 2215B Garland Ave, Nashville, TN, 37232-0654, USA.
| |
Collapse
|
13
|
Wu M, Tran PN, Sheng J, Randolph AL, Wu WW. Drug potency on inhibiting late Na + current is sensitive to gating modifier and current region where drug effects were measured. J Pharmacol Toxicol Methods 2019; 100:106605. [PMID: 31255744 DOI: 10.1016/j.vascn.2019.106605] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/18/2019] [Accepted: 06/24/2019] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Cardiac late Na+ current (INaL) contributes to ventricular action potential duration. Pathological increase in INaL is arrhythmogenic, and inhibition of INaL offers protection against ventricular repolarization disturbance. Recently, two INaL datasets generated by different laboratories that assessed current inhibition by a panel of clinical drugs as a part of the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative were published. The results revealed a surprising degree of data variability despite of the use of a standardized voltage protocol. This study investigated whether remaining procedural differences related to experimental methods and data analysis associated with these datasets can produce differences in INaL pharmacology. METHODS Whole cell voltage clamp recordings were performed on cells expressing NaV1.5 α- and β1-subunits to study: 1) the impact of gating modifiers used to augment INaL (ATX-II vs. veratridine), internal solution composition (with vs. without ATP and GTP), and recording temperature (23 °C vs 37 °C) on stability of INaL measured across the duration of a patch clamp experiment; 2) mechanisms of each gating modifier on Na+ channels; and 3) effects of six drugs (lidocaine, mexiletine, chloroquine, ranolazine, ritonavir, and verapamil) on INaL induced by either gating modifier. RESULTS Stability of INaL is affected by the choice of gating modifier, presence of nucleotides in the internal solution, and recording temperature. ATX-II and veratridine produced different changes in Na+ channel gating, inducing mechanistically distinct INaL. Drug potencies on inhibiting INaL were dependent on the choice of gating modifier and current region where drug effects were measured. DISCUSSION INaL pharmacology can be impacted by all experimental factors examined in this study. The effect of gating modifier and current region used to quantify drug inhibition alone led to 30× difference in half inhibitory concentration (IC50) for ritonavir, demonstrating that substantial difference in drug inhibition can be produced. Drug potencies on inhibiting INaL derived from different patch clamp studies may thus not be generalizable. For INaL pharmacology to be useful for in silico modeling or interpreting drug-induced changes in cardiac action potentials or ECG, standardizing INaL experimental procedures including data analysis methods is necessary to minimize data variability.
Collapse
Affiliation(s)
- Min Wu
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Phu N Tran
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Jiansong Sheng
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Aaron L Randolph
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Wendy W Wu
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America.
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Ahmad S, Tirilomis P, Pabel S, Dybkova N, Hartmann N, Molina CE, Tirilomis T, Kutschka I, Frey N, Maier LS, Hasenfuss G, Streckfuss-Bömeke K, Sossalla S. The functional consequences of sodium channel Na V 1.8 in human left ventricular hypertrophy. ESC Heart Fail 2018; 6:154-163. [PMID: 30378291 PMCID: PMC6352890 DOI: 10.1002/ehf2.12378] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/18/2018] [Accepted: 10/10/2018] [Indexed: 01/15/2023] Open
Abstract
Aims In hypertrophy and heart failure, the proarrhythmic persistent Na+ current (INaL) is enhanced. We aimed to investigate the electrophysiological role of neuronal sodium channel NaV1.8 in human hypertrophied myocardium. Methods and results Myocardial tissue of 24 patients suffering from symptomatic severe aortic stenosis and concomitant significant afterload‐induced hypertrophy with preserved ejection fraction was used and compared with 12 healthy controls. We performed quantitative real‐time PCR and western blot and detected a significant up‐regulation of NaV1.8 mRNA (2.34‐fold) and protein expression (1.96‐fold) in human hypertrophied myocardium compared with healthy hearts. Interestingly, NaV1.5 protein expression was significantly reduced in parallel (0.60‐fold). Using whole‐cell patch‐clamp technique, we found that the prominent INaL was significantly reduced after addition of novel NaV1.8‐specific blockers either A‐803467 (30 nM) or PF‐01247324 (1 μM) in human hypertrophic cardiomyocytes. This clearly demonstrates the relevant contribution of NaV1.8 to this proarrhythmic current. We observed a significant action potential duration shortening and performed confocal microscopy, demonstrating a 50% decrease in proarrhythmic diastolic sarcoplasmic reticulum (SR)‐Ca2+ leak and SR‐Ca2+ spark frequency after exposure to both NaV1.8 inhibitors. Conclusions We show for the first time that the neuronal sodium channel NaV1.8 is up‐regulated on mRNA and protein level in the human hypertrophied myocardium. Furthermore, inhibition of NaV1.8 reduced augmented INaL, abbreviated the action potential duration, and decreased the SR‐Ca2+ leak. The findings of our study suggest that NaV1.8 could be a promising antiarrhythmic therapeutic target and merits further investigation.
Collapse
Affiliation(s)
- Shakil Ahmad
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany.,Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Petros Tirilomis
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Steffen Pabel
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Nataliya Dybkova
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Nico Hartmann
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Cristina E Molina
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Theodoros Tirilomis
- Department of Thoracic, Cardiac and Vascular Surgery, University Hospital, Georg-August University Goettingen, Goettingen, Germany
| | - Ingo Kutschka
- Department of Thoracic, Cardiac and Vascular Surgery, University Hospital, Georg-August University Goettingen, Goettingen, Germany
| | - Norbert Frey
- Department of Internal Medicine III, Molecular Cardiology and Angiology, University Medical Center, Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Lars S Maier
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Katrin Streckfuss-Bömeke
- Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| | - Samuel Sossalla
- Department of Internal Medicine II, University Medical Center Regensburg, Regensburg, Germany.,Department of Cardiology and Pneumology, University Hospital, Georg-August University Goettingen, and DZHK (German Centre for Cardiovascular Research), partner site Goettingen, Goettingen, Germany
| |
Collapse
|
16
|
Khokhlova A, Balakina-Vikulova N, Katsnelson L, Iribe G, Solovyova O. Transmural cellular heterogeneity in myocardial electromechanics. J Physiol Sci 2018; 68:387-413. [PMID: 28573594 PMCID: PMC10717105 DOI: 10.1007/s12576-017-0541-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 04/24/2017] [Indexed: 12/22/2022]
Abstract
Myocardial heterogeneity is an attribute of the normal heart. We have developed integrative models of cardiomyocytes from the subendocardial (ENDO) and subepicardial (EPI) ventricular regions that take into account experimental data on specific regional features of intracellular electromechanical coupling in the guinea pig heart. The models adequately simulate experimental data on the differences in the action potential and contraction between the ENDO and EPI cells. The modeling results predict that heterogeneity in the parameters of calcium handling and myofilament mechanics in isolated ENDO and EPI cardiomyocytes are essential to produce the differences in Ca2+ transients and contraction profiles via cooperative mechanisms of mechano-calcium-electric feedback and may further slightly modulate transmural differences in the electrical properties between the cells. Simulation results predict that ENDO cells have greater sensitivity to changes in the mechanical load than EPI cells. These data are important for understanding the behavior of cardiomyocytes in the intact heart.
Collapse
Affiliation(s)
- Anastasia Khokhlova
- Ural Federal University, Ekaterinburg, Russia.
- Institute of Immunology and Physiology, Russian Academy of Sciences, 106 Pervomayskaya, Ekaterinburg, 620049, Russia.
| | - Nathalie Balakina-Vikulova
- Ural Federal University, Ekaterinburg, Russia
- Institute of Immunology and Physiology, Russian Academy of Sciences, 106 Pervomayskaya, Ekaterinburg, 620049, Russia
| | - Leonid Katsnelson
- Ural Federal University, Ekaterinburg, Russia
- Institute of Immunology and Physiology, Russian Academy of Sciences, 106 Pervomayskaya, Ekaterinburg, 620049, Russia
| | - Gentaro Iribe
- Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan
| | - Olga Solovyova
- Ural Federal University, Ekaterinburg, Russia
- Institute of Immunology and Physiology, Russian Academy of Sciences, 106 Pervomayskaya, Ekaterinburg, 620049, Russia
| |
Collapse
|
17
|
Song Y, Belardinelli L. Basal late sodium current is a significant contributor to the duration of action potential of guinea pig ventricular myocytes. Physiol Rep 2018; 5:e13295. [PMID: 28554967 PMCID: PMC5449569 DOI: 10.14814/phy2.13295] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/01/2017] [Accepted: 05/02/2017] [Indexed: 01/17/2023] Open
Abstract
In cardiac myocytes, an enhancement of late sodium current (INaL) under pathological conditions is known to cause prolongation of action potential duration (APD). This study investigated the contribution of INaL under basal, physiological conditions to the APD Whole-cell INaL and the APD of ventricular myocytes isolated from healthy adult guinea pigs were measured at 36°C. The INaL inhibitor GS967 or TTX was applied to block INaL The amplitude of basal INaL and the APD at 50% repolarization in myocytes stimulated at a frequency of 0.17 Hz were -0.24 ± 0.02 pA/pF and 229 ± 6 msec, respectively. GS967 (0.01-1 μmol/L) concentration dependently reduced the basal INaL by 18 ± 3-82 ± 4%. At the same concentrations, GS967 shortened the APD by 9 ± 2 to 25 ± 1%. Similarly, TTX at 0.1-10 μmol/L decreased the basal INaL by 13 ± 1-94 ± 1% and APD by 8 ± 1-31 ± 2%. There was a close correlation (R2 = 0.958) between the percentage inhibition of INaL and the percentage shortening of APD caused by either GS967 or TTX MTSEA (methanethiosulfonate ethylammonium, 2 mmol/L), a NaV1.5 channel blocker, reduced the INaL by 90 ± 5%, suggesting that the NaV1.5 channel isoform is the major contributor to the basal INaL KN-93 (10 μmol/L) and AIP (2 μmol/L), blockers of CaMKII, moderately reduced the basal INaL Thus, this study provides strong evidence that basal endogenous INaL is a significant contributor to the APD of cardiac myocytes. In addition, the basal INaL of guinea pig ventricular myocytes is mainly generated from NaV1.5 channel isoform and is regulated by CaMKII.
Collapse
Affiliation(s)
- Yejia Song
- University of Florida, Gainesville, Florida
| | | |
Collapse
|
18
|
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.
Collapse
Affiliation(s)
- Yejia Song
- Medicine, University of Florida, United States
| | | |
Collapse
|
19
|
Peter AK, Bjerke MA, Leinwand LA. Biology of the cardiac myocyte in heart disease. Mol Biol Cell 2017; 27:2149-60. [PMID: 27418636 PMCID: PMC4945135 DOI: 10.1091/mbc.e16-01-0038] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/23/2016] [Indexed: 12/21/2022] Open
Abstract
Cardiac hypertrophy is a major risk factor for heart failure, and it has been shown that this increase in size occurs at the level of the cardiac myocyte. Cardiac myocyte model systems have been developed to study this process. Here we focus on cell culture tools, including primary cells, immortalized cell lines, human stem cells, and their morphological and molecular responses to pathological stimuli. For each cell type, we discuss commonly used methods for inducing hypertrophy, markers of pathological hypertrophy, advantages for each model, and disadvantages to using a particular cell type over other in vitro model systems. Where applicable, we discuss how each system is used to model human disease and how these models may be applicable to current drug therapeutic strategies. Finally, we discuss the increasing use of biomaterials to mimic healthy and diseased hearts and how these matrices can contribute to in vitro model systems of cardiac cell biology.
Collapse
Affiliation(s)
- Angela K Peter
- Biofrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Maureen A Bjerke
- Biofrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309
| | - Leslie A Leinwand
- Biofrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309
| |
Collapse
|
20
|
Epifantseva I, Shaw RM. Intracellular trafficking pathways of Cx43 gap junction channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:40-47. [PMID: 28576298 DOI: 10.1016/j.bbamem.2017.05.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 12/11/2022]
Abstract
Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
Collapse
Affiliation(s)
- Irina Epifantseva
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Robin M Shaw
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.; Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA..
| |
Collapse
|
21
|
Abstract
Unique to striated muscle cells, transverse tubules (t-tubules) are membrane organelles that consist of sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network. Mature t-tubule networks are found in mammalian ventricular cardiomyocytes, with the transverse components of t-tubules occurring near sarcomeric z-discs. Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain. Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts.
Collapse
Affiliation(s)
- TingTing Hong
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
| | - Robin M Shaw
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
| |
Collapse
|
22
|
Abstract
Voltage-gated sodium channels (VGSC) are critical determinants of cellular electrical activity through the control of initiation and propagation of action potential. To ensure this role, these proteins are not consistently delivered to the plasma membrane but undergo drastic quality controls throughout various adaptive processes such as biosynthesis, anterograde and retrograde trafficking, and membrane targeting. In pathological conditions, this quality control could lead to the retention of functional VGSC and is therefore the target of different pharmacological approaches. The present chapter gives an overview of the current understanding of the facets of VGSC life cycle in the context of both cardiac and neuronal cell types.
Collapse
Affiliation(s)
- A Mercier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - P Bois
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France.
| |
Collapse
|
23
|
Liu M, Yang KC, Dudley SC. Cardiac Sodium Channel Mutations: Why so Many Phenotypes? CURRENT TOPICS IN MEMBRANES 2016; 78:513-59. [PMID: 27586294 DOI: 10.1016/bs.ctm.2015.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cardiac Na(+) channel (Nav1.5) conducts a depolarizing inward Na(+) current that is responsible for the generation of the upstroke Phase 0 of the action potential. In heart tissue, changes in Na(+) currents can affect conduction velocity and impulse propagation. The cardiac Nav1.5 is also involved in determination of the action potential duration, since some channels may reopen during the plateau phase, generating a persistent or late inward current. Mutations of cardiac Nav1.5 can induce gain or loss of channel function because of an increased late current or a decrease of peak current, respectively. Gain-of-function mutations cause Long QT syndrome type 3 and possibly atrial fibrillation, while loss-of-function channel mutations are associated with a wider variety of phenotypes, such as Brugada syndrome, cardiac conduction disease, dilated cardiomyopathy, and sick sinus node syndrome. The penetrance and phenotypes resulting from Nav1.5 mutations also vary with age, gender, body temperature, circadian rhythm, and between regions of the heart. This phenotypic variability makes it difficult to correlate genotype-phenotype. We propose that mutations are only one contributor to the phenotype and additional modifications on Nav1.5 lead to the phenotypic variability. Possible modifiers include other genetic variations and alterations in the life cycle of Nav1.5 such as gene transcription, RNA processing, translation, posttranslational modifications, trafficking, complex assembly, and degradation. In this chapter, we summarize potential modifiers of cardiac Nav1.5 that could help explain the clinically observed phenotypic variability. Consideration of these modifiers could help improve genotype-phenotype correlations and lead to new therapeutic strategies.
Collapse
Affiliation(s)
- M Liu
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - K-C Yang
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - S C Dudley
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| |
Collapse
|
24
|
Chen-Izu Y, Shaw RM, Pitt GS, Yarov-Yarovoy V, Sack JT, Abriel H, Aldrich RW, Belardinelli L, Cannell MB, Catterall WA, Chazin WJ, Chiamvimonvat N, Deschenes I, Grandi E, Hund TJ, Izu LT, Maier LS, Maltsev VA, Marionneau C, Mohler PJ, Rajamani S, Rasmusson RL, Sobie EA, Clancy CE, Bers DM. Na+ channel function, regulation, structure, trafficking and sequestration. J Physiol 2015; 593:1347-60. [PMID: 25772290 DOI: 10.1113/jphysiol.2014.281428] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/02/2014] [Indexed: 12/19/2022] Open
Abstract
This paper is the second of a series of three reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation-contraction coupling and arrhythmias: Na(+) channel and Na(+) transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on Na(+) channel function and regulation, Na(+) channel structure and function, and Na(+) channel trafficking, sequestration and complexing.
Collapse
Affiliation(s)
- Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, USA; Department of Biomedical Engineering, University of California, Davis, USA; Department of Internal Medicine/Cardiology, University of California, Davis, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
BIN1 regulates dynamic t-tubule membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:1839-47. [PMID: 26578114 DOI: 10.1016/j.bbamcr.2015.11.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/31/2015] [Accepted: 11/09/2015] [Indexed: 11/23/2022]
Abstract
Cardiac transverse tubules (t-tubules) are specific membrane organelles critical in calcium signaling and excitation-contraction coupling required for beat-to-beat heart contraction. T-tubules are highly branched and form an interconnected network that penetrates the myocyte interior to form junctions with the sarcoplasmic reticulum. T-tubules are selectively enriched with specific ion channels and proteins crucial in calcium transient development necessary in excitation-contraction coupling, thus t-tubules are a key component of cardiac myocyte function. In this review, we focus primarily on two proteins concentrated within the t-tubular network, the L-type calcium channel (LTCC) and associated membrane anchor protein, bridging integrator 1 (BIN1). Here, we provide an overview of current knowledge in t-tubule morphology, composition, microdomains, as well as the dynamics of the t-tubule network. Secondly, we highlight multiple aspects of BIN1-dependent t-tubule function, which includes forward trafficking of LTCCs to t-tubules, LTCC clustering at t-tubule surface, microdomain organization and regulation at t-tubule membrane, and the formation of a slow diffusion barrier within t-tubules. Lastly, we describe progress in characterizing how acquired human heart failure can be attributed to abnormal BIN1 transcription and associated t-tubule remodeling. Understanding BIN1-regulated cardiac t-tubule biology in human heart failure management has the dual benefit of promoting progress in both biomarker development and therapeutic target identification. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
Collapse
|
26
|
Xiao S, Shaw RM. Cardiomyocyte protein trafficking: Relevance to heart disease and opportunities for therapeutic intervention. Trends Cardiovasc Med 2014; 25:379-89. [PMID: 25649302 DOI: 10.1016/j.tcm.2014.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 12/18/2014] [Accepted: 12/20/2014] [Indexed: 11/30/2022]
Abstract
Cardiomyocytes, the individual contractile units of heart muscle, are long-lived and robust. Given the longevity of these cells, it can be easy to overlook their dynamic intracellular environment that contain rapid protein movements and frequent protein turnover. Critical gene transcription and protein translation occur continuously, as well as trafficking and localization of proteins to specific functional zones of cell membrane. As heart failure becomes an increasingly important clinical entity, growing numbers of investigative teams are examining the cell biology of healthy and diseased cardiomyocytes. In this review, we introduce the major architectural structures and types of protein movements within cardiac cells, and then review recent studies that explore the regulation of such movements. We conclude by introducing current translational directions of the basic studies with a focus on novel areas of therapeutic development.
Collapse
Affiliation(s)
- Shaohua Xiao
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Robin M Shaw
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA; Department of Medicine, University of California Los Angeles, Los Angeles, CA.
| |
Collapse
|
27
|
Abstract
Sodium current in the heart flows principally through the pore protein NaV1.5, which is part of a complex of interacting proteins that serve both to target and localize the complex in the membrane, and to modulate function by such post-translational modifications as phosphorylation and nitrosylation. Multiple mutations in seven different NaV1.5 interacting proteins have been associated with dysfunctional sodium current and inherited cardiac diseases, including long QT syndrome, Brugada syndrome, atrial fibrillation, and cardiomyopathy, as well as sudden infant death syndrome (SIDS). Mutations in as yet unidentified interacting proteins may account for cardiac disease for which a genetic basis has not yet been established. Characterizing the mechanisms by which these mutations cause disease may give insight into etiologies and treatments of more common acquired cardiac disease, such as ischemia and heart failure.
Collapse
Affiliation(s)
- John W Kyle
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| | - Jonathan C Makielski
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, Wisconsin, USA 53792
| |
Collapse
|
28
|
Mishra S, Reznikov V, Maltsev VA, Undrovinas NA, Sabbah HN, Undrovinas A. Contribution of sodium channel neuronal isoform Nav1.1 to late sodium current in ventricular myocytes from failing hearts. J Physiol 2014; 593:1409-27. [PMID: 25772296 DOI: 10.1113/jphysiol.2014.278259] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 10/03/2014] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Late Na(+) current (INaL) contributes to action potential remodelling and Ca(2+)/Na(+) changes in heart failure. The molecular identity of INaL remains unclear. The contributions of different Na(+) channel isoforms, apart from the cardiac isoform, remain unknown. We discovered and characterized a substantial contribution of neuronal isoform Nav1.1 to INaL. This new component is physiologically relevant to the control of action potential shape and duration, as well as to cell Ca(2+) dynamics, especially in heart failure. ABSTRACT Late Na(+) current (INaL) contributes to action potential (AP) duration and Ca(2+) handling in cardiac cells. Augmented INaL was implicated in delayed repolarization and impaired Ca(2+) handling in heart failure (HF). We tested if Na(+) channel (Nav) neuronal isoforms contribute to INaL and Ca(2+) cycling defects in HF in 17 dogs in which HF was achieved via sequential coronary artery embolizations. Six normal dogs served as control. Transient Na(+) current (INaT ) and INaL in left ventricular cardiomyocytes (VCMs) were recorded by patch clamp while Ca(2+) dynamics was monitored using Fluo-4. Virally delivered short interfering RNA (siRNA) ensured Nav1.1 and Nav1.5 post-transcriptional silencing. The expression of six Navs was observed in failing VCMs as follows: Nav1.5 (57.3%) > Nav1.2 (15.3%) > Nav1.1 (11.6%) > Nav2.1 (10.7%) > Nav1.3 (4.6%) > Nav1.6 (0.5%). Failing VCMs showed up-regulation of Nav1.1 expression, but reduction of Nav1.6 mRNA. A similar Nav expression pattern was found in samples from human hearts with ischaemic HF. VCMs with silenced Nav1.5 exhibited residual INaT and INaL (∼30% of control) with rightwardly shifted steady-state activation and inactivation. These currents were tetrodotoxin sensitive but resistant to MTSEA, a specific Nav1.5 blocker. The amplitude of the tetrodotoxin-sensitive INaL was 0.1709 ± 0.0299 pA pF(-1) (n = 7 cells) and the decay time constant was τ = 790 ± 76 ms (n = 5). This INaL component was lacking in VCMs with a silenced Nav1.1 gene, indicating that, among neuronal isoforms, Nav1.1 provides the largest contribution to INaL. At -10 mV this contribution is ∼60% of total INaL. Our further experimental and in silico examinations showed that this new Nav1.1 INaL component contributes to Ca(2+) accumulation in failing VCMs and modulates AP shape and duration. In conclusion, we have discovered an Nav1.1-originated INaL component in dog heart ventricular cells. This component is physiologically relevant to controlling AP shape and duration, as well as to cell Ca(2+) dynamics.
Collapse
Affiliation(s)
- Sudhish Mishra
- Department of Internal Medicine, Henry Ford Hospital, Detroit, MI, USA
| | | | | | | | | | | |
Collapse
|
29
|
Baroni D, Picco C, Barbieri R, Moran O. Antisense-mediated post-transcriptional silencing of SCN1B gene modulates sodium channel functional expression. Biol Cell 2013; 106:13-29. [PMID: 24138709 DOI: 10.1111/boc.201300040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 10/11/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND INFORMATION Voltage-dependent sodium channels are membrane proteins essential for cell excitability. They are composed by a pore-forming α-subunit and one or more β subunits. Nine α subunit and five β subunit isoforms have been identified in mammals: β1, its splice variant β1B, β2, β3 and β4. Although they do not form the ion channel pore, β subunits modulate both function as well as expression of sodium channels on cell membrane. RESULTS To investigate the role of β1 subunit on the modulation of sodium channel expression, we silenced this auxiliary subunit with specific antisense oligonucleotides (ASONs) in two rat cell lines, the GH3 and the H9C2, from neuro-ectoderm and cardiac myocyte origin, respectively. Treatment of cells with ASONs determined a reduction of about 50% of β1 subunit mRNA and protein expression in both cell lines. We found that this level of β1 subunit silencing resulted in an overall decrease of α subunit mRNA, protein expression and a decrease of sodium current density, without altering significantly the voltage-dependent and kinetic properties of the currents. In GH3 cells, the β1 subunit silencing reduced the expression of Nav1.1, Nav1.3 and Nav1.6 isoforms, whereas the Nav 1.2 isoform expression remained unaltered. The expression of the only α subunit present in H9C2 cells, the Nav1.5, was also reduced by β1 subunit silencing. CONCLUSIONS These results indicate that the β1 subunit may exert an isoform-specific fine-tuned modulation of sodium channel expression.
Collapse
|
30
|
Schroder EA, Lefta M, Zhang X, Bartos DC, Feng HZ, Zhao Y, Patwardhan A, Jin JP, Esser KA, Delisle BP. The cardiomyocyte molecular clock, regulation of Scn5a, and arrhythmia susceptibility. Am J Physiol Cell Physiol 2013; 304:C954-65. [PMID: 23364267 PMCID: PMC3651636 DOI: 10.1152/ajpcell.00383.2012] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 01/29/2013] [Indexed: 11/22/2022]
Abstract
The molecular clock mechanism underlies circadian rhythms and is defined by a transcription-translation feedback loop. Bmal1 encodes a core molecular clock transcription factor. Germline Bmal1 knockout mice show a loss of circadian variation in heart rate and blood pressure, and they develop dilated cardiomyopathy. We tested the role of the molecular clock in adult cardiomyocytes by generating mice that allow for the inducible cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1). ECG telemetry showed that cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1(-/-)) in adult mice slowed heart rate, prolonged RR and QRS intervals, and increased episodes of arrhythmia. Moreover, isolated iCSΔBmal1(-/-) hearts were more susceptible to arrhythmia during electromechanical stimulation. Examination of candidate cardiac ion channel genes showed that Scn5a, which encodes the principle cardiac voltage-gated Na(+) channel (Na(V)1.5), was circadianly expressed in control mouse and rat hearts but not in iCSΔBmal1(-/-) hearts. In vitro studies confirmed circadian expression of a human Scn5a promoter-luciferase reporter construct and determined that overexpression of clock factors transactivated the Scn5a promoter. Loss of Scn5a circadian expression in iCSΔBmal1(-/-) hearts was associated with decreased levels of Na(V)1.5 and Na(+) current in ventricular myocytes. We conclude that disruption of the molecular clock in the adult heart slows heart rate, increases arrhythmias, and decreases the functional expression of Scn5a. These findings suggest a potential link between environmental factors that alter the cardiomyocyte molecular clock and factors that influence arrhythmia susceptibility in humans.
Collapse
|
31
|
Role of “non-cardiac” voltage-gated sodium channels in cardiac cells. J Mol Cell Cardiol 2012; 53:589-90. [DOI: 10.1016/j.yjmcc.2012.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/02/2012] [Accepted: 08/07/2012] [Indexed: 11/18/2022]
|
32
|
|
33
|
Moreno JD, Clancy CE. Pathophysiology of the cardiac late Na current and its potential as a drug target. J Mol Cell Cardiol 2011; 52:608-19. [PMID: 22198344 DOI: 10.1016/j.yjmcc.2011.12.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 11/30/2011] [Accepted: 12/07/2011] [Indexed: 12/19/2022]
Abstract
A pathological increase in the late component of the cardiac Na(+) current, I(NaL), has been linked to disease manifestation in inherited and acquired cardiac diseases including the long QT variant 3 (LQT3) syndrome and heart failure. Disruption in I(NaL) leads to action potential prolongation, disruption of normal cellular repolarization, development of arrhythmia triggers, and propensity to ventricular arrhythmia. Attempts to treat arrhythmogenic sequelae from inherited and acquired syndromes pharmacologically with common Na(+) channel blockers (e.g. flecainide, lidocaine, and amiodarone) have been largely unsuccessful. This is due to drug toxicity and the failure of most current drugs to discriminate between the peak current component, chiefly responsible for single cell excitability and propagation in coupled tissue, and the late component (I(NaL)) of the Na(+) current. Although small in magnitude as compared to the peak Na(+) current (~1-3%), I(NaL) alters action potential properties and increases Na(+) loading in cardiac cells. With the increasing recognition that multiple cardiac pathological conditions share phenotypic manifestations of I(NaL) upregulation, there has been renewed interest in specific pharmacological inhibition of I(Na). The novel antianginal agent ranolazine, which shows a marked selectivity for late versus peak Na(+) current, may represent a novel drug archetype for targeted reduction of I(NaL). This article aims to review common pathophysiological mechanisms leading to enhanced I(NaL) in LQT3 and heart failure as prototypical disease conditions. Also reviewed are promising therapeutic strategies tailored to alter the molecular mechanisms underlying I(Na) mediated arrhythmia triggers.
Collapse
Affiliation(s)
- Jonathan D Moreno
- Tri-Institutional MD-PhD Program, Weill Cornell Medical College/The Rockefeller University/Sloan-Kettering Cancer Institute, New York, NY 10021, USA
| | | |
Collapse
|
34
|
Bányász T, Szentandrássy N, Tóth A, Nánási PP, Magyar J, Chen-Izu Y. Cardiac calmodulin kinase: a potential target for drug design. Curr Med Chem 2011; 18:3707-13. [PMID: 21774758 DOI: 10.2174/092986711796642409] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 07/06/2011] [Indexed: 01/01/2023]
Abstract
Therapeutic strategy for cardiac arrhythmias has undergone a remarkable change during the last decades. Currently implantable cardioverter defibrillator therapy is considered to be the most effective therapeutic method to treat malignant arrhythmias. Some even argue that there is no room for antiarrhythmic drug therapy in the age of implantable cardioverter defibrillators. However, in clinical practice, antiarrhythmic drug therapies are frequently needed, because implantable cardioverter defibrillators are not effective in certain types of arrhythmias (i.e. premature ventricular beats or atrial fibrillation). Furthermore, given the staggering cost of device therapy, it is economically imperative to develop alternative effective treatments. Cardiac ion channels are the target of a number of current treatment strategies, but therapies based on ion channel blockers only resulted in moderate success. Furthermore, these drugs are associated with an increased risk of proarrhythmia, systemic toxicity, and increased defibrillation threshold. In many cases, certain ion channel blockers were found to increase mortality. Other drug classes such as ßblockers, angiotensin-converting enzyme inhibitors, aldosterone antagonists, and statins appear to have proven efficacy for reducing cardiac mortality. These facts forced researchers to shift the focus of their research to molecular targets that act upstream of ion channels. One of these potential targets is calcium/calmodulin-dependent kinase II (CaMKII). Several lines of evidence converge to suggest that CaMKII inhibition may provide an effective treatment strategy for heart diseases. (1) Recent studies have elucidated that CaMKII plays a key role in modulating cardiac function and regulating hypertrophy development. (2) CaMKII activity has been found elevated in the failing hearts from human patients and animal models. (3) Inhibition of CaMKII activity has been shown to mitigate hypertrophy, prevent functional remodeling and reduce arrhythmogenic activity. In this review, we will discuss the structural and functional properties of CaMKII, the modes of its activation and the functional consequences of CaMKII activity on ion channels.
Collapse
Affiliation(s)
- T Bányász
- Department of Physiology, University of Debrecen, Nagyerdei krt. 98. H-4012 Debrecen, Hungary.
| | | | | | | | | | | |
Collapse
|
35
|
Rook MB, Evers MM, Vos MA, Bierhuizen MFA. Biology of cardiac sodium channel Nav1.5 expression. Cardiovasc Res 2011; 93:12-23. [PMID: 21937582 DOI: 10.1093/cvr/cvr252] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Na(v)1.5, the pore forming α-subunit of the voltage-dependent cardiac Na(+) channel, is an integral membrane protein involved in the initiation and conduction of action potentials. Mutations in the gene-encoding Na(v)1.5, SCN5A, have been associated with a variety of arrhythmic disorders, including long QT, Brugada, and sick sinus syndromes as well as progressive cardiac conduction defect and atrial standstill. Moreover, alterations in the Na(v)1.5 expression level and/or sodium current density have been frequently noticed in acquired cardiac disorders, such as heart failure. The molecular mechanisms underlying these alterations are poorly understood, but are considered essential for conception of arrhythmogenesis and the development of therapeutic strategies for prevention or treatment of arrhythmias. The unravelling of such mechanisms requires critical molecular insight into the biology of Na(v)1.5 expression and function. Therefore, the aim of this review is to provide an up-to-date account of molecular determinants of normal Na(v)1.5 expression and function. The parts of the Na(v)1.5 life cycle that are discussed include (i) regulatory aspects of the SCN5A gene and transcript structure, (ii) the nature, molecular determinants, and functional consequences of Na(v)1.5 post-translational modifications, and (iii) the role of Na(v)1.5 interacting proteins in cellular trafficking. The reviewed studies have provided valuable information on how the Na(v)1.5 expression level, localization, and biophysical properties are regulated, but also revealed that our understanding of the underlying mechanisms is still limited.
Collapse
Affiliation(s)
- Martin B Rook
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, The Netherlands
| | | | | | | |
Collapse
|
36
|
Mishra S, Undrovinas NA, Maltsev VA, Reznikov V, Sabbah HN, Undrovinas A. Post-transcriptional silencing of SCN1B and SCN2B genes modulates late sodium current in cardiac myocytes from normal dogs and dogs with chronic heart failure. Am J Physiol Heart Circ Physiol 2011; 301:H1596-605. [PMID: 21705762 DOI: 10.1152/ajpheart.00948.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The emerging paradigm for Na(+) current in heart failure (HF) is that its transient component (I(NaT)) responsible for the action potential (AP) upstroke is decreased, whereas the late component (I(NaL)) involved in AP plateau is augmented. Here we tested whether Na(v)β(1)- and Na(v)β(2)-subunits can modulate I(NaL) parameters in normal and failing ventricular cardiomyocytes (VCMs). Chronic HF was produced in nine dogs by multiple sequential coronary artery microembolizations, and six dogs served as a control. I(Na) and APs were measured by the whole cell and perforated patch-clamp in freshly isolated and cultured VCMs, respectively. I(NaL) was augmented with slower decay in HF VCMs compared with normal heart VCMs, and these properties remained unchanged within 5 days of culture. Post-transcriptional silencing SCN1B and SCN2B were achieved by virally delivered short interfering RNA (siRNA) specific to Na(v)β(1) and Na(v)β(2). The delivery and efficiency of siRNA were evaluated by green fluorescent protein expression, by the real-time RT-PCR, and Western blots, respectively. Five days after infection, the levels of mRNA and protein for Na(v)β(1) and Na(v)β(2) were reduced by >80%, but mRNA and protein of Na(v)1.5, as well as I(NaT), remained unchanged in HF VCMs. Na(v)β(1)-siRNA reduced I(NaL) density and accelerated I(NaL) two-exponential decay, whereas Na(v)β(2)-siRNA produced an opposite effect in VCMs from both normal and failing hearts. Physiological importance of the discovered I(NaL) modulation to affect AP shape and duration was illustrated both experimentally and by numerical simulations of a VCM excitation-contraction coupling model. We conclude that in myocytes of normal and failing dog hearts Na(v)β(1) and Na(v)β(2) exhibit oppositely directed modulation of I(NaL).
Collapse
Affiliation(s)
- Sudhish Mishra
- Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan 48202-2689, USA
| | | | | | | | | | | |
Collapse
|
37
|
Yao L, Fan P, Jiang Z, Viatchenko-Karpinski S, Wu Y, Kornyeyev D, Hirakawa R, Budas GR, Rajamani S, Shryock JC, Belardinelli L. Nav1.5-dependent persistent Na+ influx activates CaMKII in rat ventricular myocytes and N1325S mice. Am J Physiol Cell Physiol 2011; 301:C577-86. [PMID: 21677263 DOI: 10.1152/ajpcell.00125.2011] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Late Na(+) current (I(NaL)) and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) are both increased in the diseased heart. Recently, CaMKII was found to phosphorylate the Na(+) channel 1.5 (Na(v)1.5), resulting in enhanced I(NaL). Conversely, an increase of I(NaL) would be expected to cause elevation of intracellular Ca(2+) and activation of CaMKII. However, a relationship between enhancement of I(NaL) and activation of CaMKII has yet to be demonstrated. We investigated whether Na(+) influx via Na(v)1.5 leads to CaMKII activation and explored the functional significance of this pathway. In neonatal rat ventricular myocytes (NRVM), treatment with the I(NaL) activators anemone toxin II (ATX-II) or veratridine increased CaMKII autophosphorylation and increased phosphorylation of CaMKII substrates phospholamban and ryanodine receptor 2. Knockdown of Na(v)1.5 (but not Na(v)1.1 or Na(v)1.2) prevented ATX-II-induced CaMKII phosphorylation, providing evidence for a specific role of Na(v)1.5 in CaMKII activation. In support of this view, CaMKII activity was also increased in hearts of transgenic mice overexpressing a gain-of-function Na(v)1.5 mutant (N(1325)S). The effects of both ATX-II and the N(1325)S mutation were reversed by either I(NaL) inhibition (with ranolazine or tetrodotoxin) or CaMKII inhibition (with KN93 or autocamtide 2-related inhibitory peptide). Furthermore, ATX-II treatment also induced CaMKII-Na(v)1.5 coimmunoprecipitation. The same association between CaMKII and Na(v)1.5 was also found in N(1325)S mice, suggesting a direct protein-protein interaction. Pharmacological inhibitions of either CaMKII or I(NaL) also prevented ATX-II-induced cell death in NRVM and reduced the incidence of polymorphic ventricular tachycardia induced by ATX-II in rat perfused hearts. Taken together, these results suggest that a Na(v)1.5-dependent increase in Na(+) influx leads to activation of CaMKII, which in turn phosphorylates Na(v)1.5, further promoting Na(+) influx. Pharmacological inhibition of either CaMKII or Na(v)1.5 can ameliorate cardiac dysfunction caused by excessive Na(+) influx.
Collapse
Affiliation(s)
- Lina Yao
- Department of Biology, Gilead Sciences, Palo Alto, California 94304, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Aslanidi OV, Sleiman RN, Boyett MR, Hancox JC, Zhang H. Ionic mechanisms for electrical heterogeneity between rabbit Purkinje fiber and ventricular cells. Biophys J 2010; 98:2420-31. [PMID: 20513385 DOI: 10.1016/j.bpj.2010.02.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 01/14/2010] [Accepted: 02/12/2010] [Indexed: 10/19/2022] Open
Abstract
The intrinsic heterogeneity of electrical action potential (AP) properties between Purkinje fibers (PFs) and the ventricular wall, as well as within the wall, plays an important role in ensuring successful excitation of the ventricles. It can also be proarrhythmic due to nonuniform repolarization across the Purkinje-ventricular junction. However, the ionic mechanisms that underlie the marked AP differences between PFs and ventricular cells are not fully characterized. We studied such mechanisms by developing a new family of biophysically detailed AP models for rabbit PF cells and three transmural ventricular cell types. The models were based on and validated against experimental data recorded from rabbit at ionic channel, single cell, and tissue levels. They were then used to determine the functional roles of each individual ionic channel current in modulating the AP heterogeneity at the rabbit Purkinje-ventricular junction, and to identify specific currents responsible for the differential response of PFs and ventricular cells to pharmacological interventions.
Collapse
Affiliation(s)
- Oleg V Aslanidi
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
| | | | | | | | | |
Collapse
|
39
|
Abstract
Congestive heart failure is a leading cause of morbidity and mortality. Congestive heart failure is marked by atrial and ventricular enlargements and reduced cardiac contractility and an association with an increased incidence of atrial and ventricular arrhythmias and sudden cardiac death. Dysfunctional ion channel function is one of the major underlying mechanisms of the reduced contractility and arrhythmias. In this review, we explore the utility of ion channels, transporters, and pumps as targets for the treatment of heart failure, focusing predominantly on the treatment for reduced contractility and arrhythmias.
Collapse
|
40
|
Maltsev VA, Kyle JW, Undrovinas A. Late Na+ current produced by human cardiac Na+ channel isoform Nav1.5 is modulated by its beta1 subunit. J Physiol Sci 2009; 59:217-25. [PMID: 19340536 PMCID: PMC2744134 DOI: 10.1007/s12576-009-0029-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 02/02/2009] [Indexed: 01/26/2023]
Abstract
Experimental data accumulated over the past decade show the emerging importance of the late sodium current (I(NaL)) for the function of both normal and, especially, failing myocardium, in which I(NaL) is reportedly increased. While recent molecular studies identified the cardiac Na(+) channel (NaCh) alpha subunit isoform (Na(v)1.5) as a major contributor to I (NaL), the molecular mechanisms underlying alterations of I(NaL) in heart failure (HF) are still unknown. Here we tested the hypothesis that I(NaL) is modulated by the NaCh auxiliary beta subunits. tsA201 cells were transfected simultaneously with human Na(v)1.5 (former hH1a) and cardiac beta(1) or beta(2) subunits, and whole-cell patch-clamp experiments were performed. We found that I(NaL) decay kinetics were significantly slower in cells expressing alpha + beta(1) (time constant tau = 0.73 +/- 0.16 s, n = 14, mean +/- SEM, P < 0.05) but remained unchanged in cells expressing alpha + beta(2) (tau = 0.52 +/- 0.09 s, n = 5), compared with cells expressing Na(v)1.5 alone (tau = 0.54 +/- 0.09 s, n = 20). Also, beta(1), but not beta(2), dramatically increased I(NaL) relative to the maximum peak current, I(NaT) (2.3 +/- 0.48%, n = 14 vs. 0.48 +/- 0.07%, n = 6, P < 0.05, respectively) and produced a rightward shift of the steady-state availability curve. We conclude that the auxiliary beta(1) subunit modulates I(NaL), produced by the human cardiac Na(+) channel Na(v)1.5 by slowing its decay and increasing I(NaL) amplitude relative to I(NaT). Because expression of Na(v)1.5 reportedly decreases but beta(1) remains unchanged in chronic HF, the relatively higher expression of beta(1) may contribute to the known I(NaL) increase in HF via the modulation mechanism found in this study.
Collapse
Affiliation(s)
- Victor A. Maltsev
- Department of Internal Medicine, Cardiovascular Research, Henry Ford Hospital Detroit, Education and Research Bldg. Room 4015, 2799 West Grand Boulevard, Detroit, MI 48202-2689 USA
- Present Address: Gerontology Research Center, National Institute on Aging, NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825 USA
| | - John W. Kyle
- Department of Neurobiology, Pharmacology, and Physiology, University of Chicago, Chicago, IL USA
| | - Albertas Undrovinas
- Department of Internal Medicine, Cardiovascular Research, Henry Ford Hospital Detroit, Education and Research Bldg. Room 4015, 2799 West Grand Boulevard, Detroit, MI 48202-2689 USA
| |
Collapse
|
41
|
|