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Williams ZJ, Alvarez-Laviada A, Hoagland D, Jourdan LJ, Poelzing S, Gorelik J, Gourdie RG. Development and characterization of the mode-of-action of inhibitory and agonist peptides targeting the voltage-gated sodium channel SCN1B beta-subunit. J Mol Cell Cardiol 2024; 194:32-45. [PMID: 38942073 DOI: 10.1016/j.yjmcc.2024.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 06/07/2024] [Accepted: 06/19/2024] [Indexed: 06/30/2024]
Abstract
Cardiac arrhythmia treatment is a clinical challenge necessitating safer and more effective therapies. Recent studies have highlighted the role of the perinexus, an intercalated disc nanodomain enriched in voltage-gated sodium channels including both Nav1.5 and β1 subunits, adjacent to gap junctions. These findings offer insights into action potential conduction in the heart. A 19-amino acid SCN1B (β1/β1B) mimetic peptide, βadp1, disrupts VGSC beta subunit-mediated adhesion in cardiac perinexii, inducing arrhythmogenic changes. We aimed to explore βadp1's mechanism and develop novel SCN1B mimetic peptides affecting β1-mediated adhesion. Using patch clamp assays in neonatal rat cardiomyocytes and electric cell substrate impedance sensing (ECIS) in β1-expressing cells, we observed βadp1 maintained inhibitory effects for up to 5 h. A shorter peptide (LQLEED) based on the carboxyl-terminus of βadp1 mimicked this inhibitory effect, while dimeric peptides containing repeated LQLEED sequences paradoxically promoted intercellular adhesion over longer time courses. Moreover, we found a link between these peptides and β1-regulated intramembrane proteolysis (RIP) - a signaling pathway effecting gene transcription including that of VGSC subunits. βadp1 increased RIP continuously over 48 h, while dimeric agonists acutely boosted RIP for up to 6 h. In the presence of DAPT, an RIP inhibitor, βadp1's effects on ECIS-measured intercellular adhesion was reduced, suggesting a relationship between RIP and the peptide's inhibitory action. In conclusion, novel SCN1B (β1/β1B) mimetic peptides are reported with the potential to modulate intercellular VGSC β1-mediated adhesion, potentially through β1 RIP. These findings suggest a path towards the development of anti-arrhythmic drugs targeting the perinexus.
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Affiliation(s)
- Zachary J Williams
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, VA, United States
| | | | - Daniel Hoagland
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, VA, United States
| | - L Jane Jourdan
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, VA, United States
| | - Steven Poelzing
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, VA, United States; School of Medicine, Virgina Polytechnic University, Roanoke, VA, United States; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic University, Roanoke, VA, United States
| | - Julia Gorelik
- Department of Myocardial Function, Imperial College London, London, United Kingdom
| | - Robert G Gourdie
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, VA, United States; School of Medicine, Virgina Polytechnic University, Roanoke, VA, United States; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic University, Roanoke, VA, United States.
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Williams ZJ, Payne LB, Wu X, Gourdie RG. New focus on cardiac voltage-gated sodium channel β1 and β1B: Novel targets for treating and understanding arrhythmias? Heart Rhythm 2024:S1547-5271(24)02742-5. [PMID: 38908461 DOI: 10.1016/j.hrthm.2024.06.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/09/2024] [Accepted: 06/17/2024] [Indexed: 06/24/2024]
Abstract
Voltage-gated sodium channels (VGSCs) are transmembrane protein complexes that are vital to the generation and propagation of action potentials in nerve and muscle fibers. The canonical VGSC is generally conceived as a heterotrimeric complex formed by 2 classes of membrane-spanning subunit: an α-subunit (pore forming) and 2 β-subunits (non-pore forming). NaV1.5 is the main sodium channel α-subunit of mammalian ventricle, with lower amounts of other α-subunits, including NaV1.6, being present. There are 4 β-subunits (β1-β4) encoded by 4 genes (SCN1B-SCN4B), each of which is expressed in cardiac tissues. Recent studies suggest that in addition to assignments in channel gating and trafficking, products of Scn1b may have novel roles in conduction of action potential in the heart and intracellular signaling. This includes evidence that the β-subunit extracellular amino-terminal domain facilitates adhesive interactions in intercalated discs and that its carboxyl-terminal region is a substrate for a regulated intramembrane proteolysis (RIP) signaling pathway, with a carboxyl-terminal peptide generated by β1 RIP trafficked to the nucleus and altering transcription of various genes, including NaV1.5. In addition to β1, the Scn1b gene encodes for an alternative splice variant, β1B, which contains an identical extracellular adhesion domain to β1 but has a unique carboxyl-terminus. Although β1B is generally understood to be a secreted variant, evidence indicates that when co-expressed with NaV1.5, it is maintained at the cell membrane, suggesting potential unique roles for this understudied protein. In this review, we focus on what is known of the 2 β-subunit variants encoded by Scn1b in heart, with particular focus on recent findings and the questions raised by this new information. We also explore data that indicate β1 and β1B may be attractive targets for novel antiarrhythmic therapeutics.
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Affiliation(s)
- Zachary J Williams
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Laura Beth Payne
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Xiaobo Wu
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia
| | - Robert G Gourdie
- Fralin Biomedical Research Institute, Virginia Polytechnic University, Roanoke, Virginia; School of Medicine, Virgina Polytechnic University, Roanoke, Virginia; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic University, Blacksburg, Virginia.
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Hodges SL, Bouza AA, Isom LL. Therapeutic Potential of Targeting Regulated Intramembrane Proteolysis Mechanisms of Voltage-Gated Ion Channel Subunits and Cell Adhesion Molecules. Pharmacol Rev 2022; 74:1028-1048. [PMID: 36113879 PMCID: PMC9553118 DOI: 10.1124/pharmrev.121.000340] [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: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 10/03/2023] Open
Abstract
Several integral membrane proteins undergo regulated intramembrane proteolysis (RIP), a tightly controlled process through which cells transmit information across and between intracellular compartments. RIP generates biologically active peptides by a series of proteolytic cleavage events carried out by two primary groups of enzymes: sheddases and intramembrane-cleaving proteases (iCLiPs). Following RIP, fragments of both pore-forming and non-pore-forming ion channel subunits, as well as immunoglobulin super family (IgSF) members, have been shown to translocate to the nucleus to function in transcriptional regulation. As an example, the voltage-gated sodium channel β1 subunit, which is also an IgSF-cell adhesion molecule (CAM), is a substrate for RIP. β1 RIP results in generation of a soluble intracellular domain, which can regulate gene expression in the nucleus. In this review, we discuss the proposed RIP mechanisms of voltage-gated sodium, potassium, and calcium channel subunits as well as the roles of their generated proteolytic products in the nucleus. We also discuss other RIP substrates that are cleaved by similar sheddases and iCLiPs, such as IgSF macromolecules, including CAMs, whose proteolytically generated fragments function in the nucleus. Importantly, dysfunctional RIP mechanisms are linked to human disease. Thus, we will also review how understanding RIP events and subsequent signaling processes involving ion channel subunits and IgSF proteins may lead to the discovery of novel therapeutic targets. SIGNIFICANCE STATEMENT: Several ion channel subunits and immunoglobulin superfamily molecules have been identified as substrates of regulated intramembrane proteolysis (RIP). This signal transduction mechanism, which generates polypeptide fragments that translocate to the nucleus, is an important regulator of gene transcription. RIP may impact diseases of excitability, including epilepsy, cardiac arrhythmia, and sudden death syndromes. A thorough understanding of the role of RIP in gene regulation is critical as it may reveal novel therapeutic strategies for the treatment of previously intractable diseases.
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Affiliation(s)
- Samantha L Hodges
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Alexandra A Bouza
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Lori L Isom
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
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Lin CH, Ho CJ, Lu YT, Tsai MH. Response to Sodium Channel blocking Antiseizure medications and coding polymorphisms of Sodium Channel genes in Taiwanese epilepsy patients. BMC Neurol 2021; 21:367. [PMID: 34556045 PMCID: PMC8459515 DOI: 10.1186/s12883-021-02395-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Background Many antiseizure medications (ASMs) control seizures by blocking voltage-dependent sodium channels. Polymorphisms of sodium channel genes may affect the response to ASMs due to altering the effect of ASMs on blocking sodium channels. Methods We conducted a retrospective study of epilepsy patients followed up at the Neurological Department of Kaohsiung Chang Gung Memorial Hospital, Taiwan between January 2010 and December 2018. We categorized the patients into response, partial response, and failure to sodium channel blocking ASM groups. Sodium channel blocking ASMs included phenytoin, carbamazepine, lamotrigine, oxcarbazepine, lacosamide, zonisamide, topiramate, and valproic acid. A subgroup of predominant sodium channel blocking ASMs included phenytoin, carbamazepine, lamotrigine, oxcarbazepine, and lacosamide. Associations between the response of ASMs and single-nucleotide polymorphisms of SCN1A, SCN1B, SCN2A, and SCN9A were analyzed. Results Two hundred Taiwanese patients and 21 single-nucleotide polymorphisms among SCN1A, SCN1B, SCN2A, and SCN9A were evaluated. We found allele C of rs55742440 in SCN1B was statistically significantly associated with not achieving seizure-free with sodium channel blocking ASMs. For the predominant sodium channel blocking ASMs group, no SNPs were associated with the response of ASMs. Conclusion Single-nucleotide polymorphism in SCN1B was associated with the response to sodium channel blocking ASMs. This highlights the possibility that beta subunits may affect the function of sodium channels and resulted in different responsiveness to ASMs. Supplementary Information The online version contains supplementary material available at 10.1186/s12883-021-02395-2.
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Affiliation(s)
- Chih-Hsiang Lin
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Colleague of Medicine, Chang Gung University, Kaohsiung, Kaohsiung City, 83301, Taiwan
| | - Chen-Jui Ho
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Colleague of Medicine, Chang Gung University, Kaohsiung, Kaohsiung City, 83301, Taiwan
| | - Yan-Ting Lu
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Colleague of Medicine, Chang Gung University, Kaohsiung, Kaohsiung City, 83301, Taiwan
| | - Meng-Han Tsai
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Colleague of Medicine, Chang Gung University, Kaohsiung, Kaohsiung City, 83301, Taiwan. .,School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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Nijak A, Labro AJ, De Wilde H, Dewals W, Peigneur S, Tytgat J, Snyders D, Sieliwonczyk E, Simons E, Van Craenenbroeck E, Schepers D, Van Laer L, Saenen J, Loeys B, Alaerts M. Compound Heterozygous SCN5A Mutations in Severe Sodium Channelopathy With Brugada Syndrome: A Case Report. Front Cardiovasc Med 2020; 7:117. [PMID: 32850980 PMCID: PMC7396896 DOI: 10.3389/fcvm.2020.00117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 06/04/2020] [Indexed: 12/16/2022] Open
Abstract
Aims: Brugada syndrome (BrS) is an inherited cardiac arrhythmia with an increased risk for sudden cardiac death (SCD). About 20% of BrS cases are explained by mutations in the SCN5A gene, encoding the main cardiac sodium Nav1.5 channel. Here we present a severe case of cardiac sodium channelopathy with BrS caused by SCN5A compound heterozygous mutations. We performed a genetic analysis of SCN5A in a male proband who collapsed during cycling at the age of 2 years. Because of atrial standstill, he received a pacemaker, and at the age of 3 years, he experienced a collapse anew with left-sided brain stroke. A later ECG taken during a fever unmasked a characteristic BrS type-1 pattern. The functional effect of the detected genetic variants was investigated. Methods and Results: Next-generation sequencing allowed the detection of two SCN5A variants in trans: c.4813+3_4813+6dupGGGT-a Belgian founder mutation-and c.4711 T>C, p.Phe1571Leu. A familial segregation analysis showed the presence of the founder mutation in the proband's affected father and paternal aunt and the de novo occurrence of the p.Phe1571Leu. The functional effect of the founder mutation was previously described as a loss-of-function. We performed a functional analysis of the p.Phe571Leu variant in HEK293 cells alone or co-expressed with the β1-subunit. Compared to the SCN5A wild type, p.Phe1571Leu displayed a hyperpolarizing shift in the voltage dependence of inactivation (loss-of-function), while the activation parameters were unaffected. Using the peptide toxin nemertide α-1, the variant's loss-of-function effect could be restored due to a toxin-dependent reduction of channel inactivation. Conclusion: This is the first report providing support for the pathogenicity of the p.Phe1571Leu SCN5A variant which, together with the c.4813+3_4813+6dupGGGT founder mutation, explains the severity of the phenotype of cardiac sodium channelopathy with BrS in the presented case.
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Affiliation(s)
- Aleksandra Nijak
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Alain J Labro
- Laboratory of Molecular, Cellular and Network Excitability, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Hans De Wilde
- Department of Paediatric Cardiology, Antwerp University Hospital, Antwerp, Belgium.,Department of Invasive Cardiology and Electrophysiology, Ghent University Hospital, Ghent, Belgium
| | - Wendy Dewals
- Department of Paediatric Cardiology, Antwerp University Hospital, Antwerp, Belgium
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Dirk Snyders
- Laboratory of Molecular, Cellular and Network Excitability, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Ewa Sieliwonczyk
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Eline Simons
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | | | - Dorien Schepers
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Lut Van Laer
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Johan Saenen
- Department of Cardiology, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Bart Loeys
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium.,Department of Human Genetics, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Maaike Alaerts
- Center of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
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Wang L, Han Z, Dai J, Cao K. Brugada Syndrome Caused by Sodium Channel Dysfunction Associated with a SCN1B Variant A197V. Arch Med Res 2020; 51:245-253. [PMID: 32192759 DOI: 10.1016/j.arcmed.2020.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 01/18/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022]
Abstract
OBJECTIVE We aimed to identify and characterize a SCN1B variant, A197V, associated with Brugada Syndrome (BrS). METHODS Whole-exome sequencing was employed to explore the potential causative genes in 8 unrelated clinically diagnosed BrS patients. A197V variant was only detected in exon 4 of SCN1B in a 46 year old patient, who was admitted due to syncope. Wild type (WT) and mutant (A197V) genes were co-expressed with SCN5A in human embryonic kidney cells (HEK293 cells) and studied using whole-cell patch clamp and immunodetection techniques. RESULTS Coexpression of 5A/WT + 1B/A197V resulted in a marked decrease in current density compared to 5A/WT + 1B/WT. The activation velocity was decelerated by A197V mutation. No significant changes were observed in recovery from inactivation parameters. Cell surface protein analyses confirmed that Nav1.5 channel membrane distribution was affected by A197V mutation. CONCLUSIONS The current study is the first to report the functional analysis of SCN1B/ A197V, serving as a substrate responsible for BrS.
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Affiliation(s)
- Linlin Wang
- Department of Cardiology, Nanjing Brain Hospital, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Zhonglin Han
- Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, People's Republic of China
| | - Jian Dai
- Department of Cardiology, Nanjing Brain Hospital, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Kejiang Cao
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China.
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Van de Sande DV, Kopljar I, Teisman A, Gallacher DJ, Snyders DJ, Lu HR, Labro AJ. Pharmacological Profile of the Sodium Current in Human Stem Cell-Derived Cardiomyocytes Compares to Heterologous Nav1.5+β1 Model. Front Pharmacol 2019; 10:1374. [PMID: 31920633 PMCID: PMC6917651 DOI: 10.3389/fphar.2019.01374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 10/29/2019] [Indexed: 12/20/2022] Open
Abstract
The cardiac Nav1.5 mediated sodium current (INa) generates the upstroke of the action potential in atrial and ventricular myocytes. Drugs that modulate this current can therefore be antiarrhythmic or proarrhythmic, which requires preclinical evaluation of their potential drug-induced inhibition or modulation of Nav1.5. Since Nav1.5 assembles with, and is modulated by, the auxiliary β1-subunit, this subunit can also affect the channel’s pharmacological response. To investigate this, the effect of known Nav1.5 inhibitors was compared between COS-7 cells expressing Nav1.5 or Nav1.5+β1 using whole-cell voltage clamp experiments. For the open state class Ia blockers ajmaline and quinidine, and class Ic drug flecainide, the affinity did not differ between both models. For class Ib drugs phenytoin and lidocaine, which are inactivated state blockers, the affinity decreased more than a twofold when β1 was present. Thus, β1 did not influence the affinity for the class Ia and Ic compounds but it did so for the class Ib drugs. Human stem cell-derived cardiomyocytes (hSC-CMs) are a promising translational cell source for in vitro models that express a representative repertoire of channels and auxiliary proteins, including β1. Therefore, we subsequently evaluated the same drugs for their response on the INa in hSC-CMs. Consequently, it was expected and confirmed that the drug response of INa in hSC-CMs compares best to INa expressed by Nav1.5+β1.
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Affiliation(s)
- Dieter V Van de Sande
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Ivan Kopljar
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium.,Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Ard Teisman
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - David J Gallacher
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Dirk J Snyders
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Hua Rong Lu
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alain J Labro
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
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Mutation E87Q of the β1-subunit impairs the maturation of the cardiac voltage-dependent sodium channel. Sci Rep 2017; 7:10683. [PMID: 28878239 PMCID: PMC5587543 DOI: 10.1038/s41598-017-10645-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022] Open
Abstract
Voltage-dependent sodium channels are responsible of the rising phase of the action potential in excitable cells. These membrane integral proteins are composed by a pore-forming α-subunit, and one or more auxiliary β subunits. Mutation E87Q of the β1 subunit is correlated with Brugada syndrome, a genetic disease characterised by ventricular fibrillation, right precordial ST segment elevation on ECG and sudden cardiac death. Heterologous expression of E87Q-β1 subunit in CHO cells determines a reduced sodium channel functional expression. The effect the E87Q mutation of the β1 subunit on sodium currents and α protein expression is correlated with a reduced availability of the mature form of the α subunit in the plasma membrane. This finding offers a new target for the treatment of the Brugada syndrome, based on protein maturation management. This work highlights the role played by the β1 subunit in the maturation and expression of the entire sodium channel complex and underlines how the defective interaction between the sodium channel constituents could lead to a disabling pathological condition.
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Shimizu H, Tosaki A, Ohsawa N, Ishizuka-Katsura Y, Shoji S, Miyazaki H, Oyama F, Terada T, Shirouzu M, Sekine SI, Nukina N, Yokoyama S. Parallel homodimer structures of the extracellular domains of the voltage-gated sodium channel β4 subunit explain its role in cell-cell adhesion. J Biol Chem 2017; 292:13428-13440. [PMID: 28655765 PMCID: PMC5555201 DOI: 10.1074/jbc.m117.786509] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/26/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are transmembrane proteins required for the generation of action potentials in excitable cells and essential for propagating electrical impulses along nerve cells. VGSCs are complexes of a pore-forming α subunit and auxiliary β subunits, designated as β1/β1B-β4 (encoded by SCN1B-4B, respectively), which also function in cell-cell adhesion. We previously reported the structural basis for the trans homophilic interaction of the β4 subunit, which contributes to its adhesive function. Here, using crystallographic and biochemical analyses, we show that the β4 extracellular domains directly interact with each other in a parallel manner that involves an intermolecular disulfide bond between the unpaired Cys residues (Cys58) in the loop connecting strands B and C and intermolecular hydrophobic and hydrogen-bonding interactions of the N-terminal segments (Ser30-Val35). Under reducing conditions, an N-terminally deleted β4 mutant exhibited decreased cell adhesion compared with the wild type, indicating that the β4 cis dimer contributes to the trans homophilic interaction of β4 in cell-cell adhesion. Furthermore, this mutant exhibited increased association with the α subunit, indicating that the cis dimerization of β4 affects α-β4 complex formation. These observations provide the structural basis for the parallel dimer formation of β4 in VGSCs and reveal its mechanism in cell-cell adhesion.
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Affiliation(s)
- Hideaki Shimizu
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan.,the Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Asako Tosaki
- the Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Noboru Ohsawa
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan
| | - Yoshiko Ishizuka-Katsura
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan
| | - Shisako Shoji
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan
| | - Haruko Miyazaki
- the Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.,the Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan.,the Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, 1-3 Tatara Miyakodani, Kyotanabe-shi, Kyoto 610-0394, Japan
| | - Fumitaka Oyama
- the Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.,the Department of Chemistry and Life Science, Kogakuin University, Hachioji, Tokyo 192-0015, Japan, and
| | - Takaho Terada
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Structural Biology Laboratory, Tsurumi, Yokohama 230-0045, Japan
| | - Mikako Shirouzu
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan
| | - Shun-Ichi Sekine
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.,the RIKEN Center for Life Science Technologies, Tsurumi, Yokohama 230-0045, Japan
| | - Nobuyuki Nukina
- the Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.,the Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan.,the Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, 1-3 Tatara Miyakodani, Kyotanabe-shi, Kyoto 610-0394, Japan
| | - Shigeyuki Yokoyama
- From the RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan, .,the RIKEN Structural Biology Laboratory, Tsurumi, Yokohama 230-0045, Japan
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