Mechanistic insights into the interaction of the MOG1 protein with the cardiac sodium channel Nav1.5 clarify the molecular basis of Brugada syndrome

Nav1.5 is the α-subunit of the cardiac sodium channel complex. Abnormal expression of Nav1.5 on the cell surface because of mutations that disrupt Nav1.5 trafficking causes Brugada syndrome (BrS), sick sinus syndrome (SSS), cardiac conduction disease, dilated cardiomyopathy, and sudden infant death syndrome. We and others previously reported that Ran-binding protein MOG1 (MOG1), a small protein that interacts with Nav1.5, promotes Nav1.5 intracellular trafficking to plasma membranes and that a substitution in MOG1, E83D, causes BrS. However, the molecular basis for the MOG1/Nav1.5 interaction and how the E83D substitution causes BrS remains unknown. Here, we assessed the effects of defined MOG1 deletions and alanine-scanning substitutions on MOG1's interaction with Nav1.5. Large deletion analysis mapped the MOG1 domain required for the interaction with Nav1.5 to the region spanning amino acids 146–174, and a refined deletion analysis further narrowed this domain to amino acids 146–155. Site-directed mutagenesis further revealed that Asp-148, Arg-150, and Ser-151 cluster in a peptide loop essential for binding to Nav1.5. GST pulldown and electrophysiological analyses disclosed that the substitutions E83D, D148Q, R150Q, and S151Q disrupt MOG1's interaction with Nav1.5 and significantly reduce its trafficking to the cell surface. Examination of MOG1's 3D structure revealed that Glu-83 and the loop containing Asp-148, Arg-150, and Ser-151 are spatially proximal, suggesting that these residues form a critical binding site for Nav1.5. In conclusion, our findings identify the structural elements in MOG1 that are crucial for its interaction with Nav1.5 and improve our understanding of how the E83D substitution causes BrS.

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Cardiac sodium channel, its mutations and their spectrum of arrhythmia phenotypes

Journal of Human Growth and Development ◽

10.7322/jhgd.122759 ◽

2016 ◽

Vol 26 (3) ◽

pp. 281 ◽

Cited By ~ 1

Author(s):

Andrés Ricardo Pérez-Riera ◽

Rodrigo Daminello Raimundo ◽

Rodrigo Akira Watanabe ◽

José Luiz Figueiredo ◽

Luiz Carlos de Abreu

Keyword(s):

Sodium Channel ◽

Cardiac Muscle ◽

Heart Function ◽

Heart Diseases ◽

Cardiac Conduction ◽

Activation Process ◽

Α Subunit ◽

Cardiac Sodium Channel ◽

Wide Range ◽

Scn5a Gene

The mechanisms of cellular excitability and propagation of electrical signals in the cardiac muscle are very important functionally and pathologically. The heart is constituted by three types of muscle: atrial, ventricular, and specialized excitatory and conducting fi bers. From a physiological and pathophysiological point of view, the conformational states of the sodium channel during heart function constitute a signifi cant aspect for the diagnosis and treatment of heart diseases. Functional states of the sodium channel (closed, open, and inactivated) and their structure help to understand the cardiac regulation processes. There are areas in the cardiac muscle with anatomical and functional differentiation that present automatism, thus subjecting the rest of the fi bers to their own rhythm. The rate of these (pacemaker) areas could be altered by modifi cations in ions, temperature and especially, the autonomic system. Excitability is a property of the myocardium to react when stimulated. Another electrical property is conductivity, which is characterized by a conduction and activation process, where the action potential, by the all-or-nothing law, travels throughout the heart. Heart relaxation also stands out as an active process, dependent on the energetic output and on specificion and enzymatic actions, with the role of sodium channel being outstanding in the functional process. In the gene mutation aspects that encode the rapid sodium channel (SCN5A gene), this channel is responsible for several phenotypes, such as Brugada syndrome, idiopathic ventricular fibrillation, dilated cardiomyopathy, early repolarization syndrome, familial atrial fibrillation, variant 3 of long QT syndrome, multifocal ectopic ventricular contractions originating in Purkinje arborizations, progressive cardiac conduction defect (Lenègre disease), sudden infant death syndrome, sick sinus syndrome, sudden unexplained nocturnal death syndrome, among other sodium channel alterations with clinical overlapping. Finally, it seems appropriate to consider the “sodium channel syndrome” (mutations in the gene of the α subunit of the sodium channel, SCN5A gene) as a single clinical entity that may manifest in a wide range of phenotypes, to thus have a better insight on these cardiac syndromes and potential outcomes for their clinical treatment.

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A mutant cardiac sodium channel with multiple biophysical defects associated with overlapping clinical features of Brugada syndrome and cardiac conduction disease

Cardiovascular Research ◽

10.1016/s0008-6363(01)00494-1 ◽

2002 ◽

Vol 53 (2) ◽

pp. 348-354 ◽

Cited By ~ 46

Author(s):

N Shirai

Keyword(s):

Sodium Channel ◽

Clinical Features ◽

Brugada Syndrome ◽

Cardiac Conduction ◽

Cardiac Sodium Channel

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P1597Two novel mutations in SCN5A gene cause enhanced inactivation and lead to Brugada syndrome

European Heart Journal ◽

10.1093/eurheartj/ehz748.0356 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

A Zaytseva ◽

A V Karpushev ◽

Y Fomicheva ◽

...

Keyword(s):

Steady State ◽

Sodium Channel ◽

Brugada Syndrome ◽

Slow Inactivation ◽

Fast Inactivation ◽

Novel Mutations ◽

Patch Clamp Technique ◽

Inactivation Curve ◽

Voltage Gated ◽

Cardiac Sodium Channel

Abstract Background Mutations in gene SCN5A, encoding cardiac potential-dependent sodium channel Nav1.5, are associated with various arrhythmogenic disorders among which the Brugada syndrome (BrS) and the Long QT syndrome (LQT) are the best characterized. BrS1 is associated with sodium channel dysfunction, which can be reflected by decreased current, impaired activation and enhanced inactivation. We found two novel mutations in our patients with BrS and explored their effect on fast and slow inactivation of cardiac sodium channel. Purpose The aim of this study was to investigate the effect of BrS (Y739D, L1582P) mutations on different inactivation processes in in vitro model. Methods Y739D and L1582P substitutions were introduced in SCN5A cDNA using site-directed mutagenesis. Sodium currents were recorded at room temperature in transfected HEK293-T cells using patch-clamp technique with holding potential −100 mV. In order to access the fast steady-state inactivation curve we used double-pulse protocol with 10 ms prepulses. To analyze voltage-dependence of slow inactivation we used two-pulse protocol with 10s prepulse, 20ms test pulse and 25ms interpulse at −100mV to allow recovery from fast inactivation. Electrophysiological measurements are presented as mean ±SEM. Results Y739D mutation affects highly conserved tyrosine 739 among voltage-gated sodium and calcium channels in the segment IIS2. Mutation L1582P located in the loop IVS4-S5, and leucine in this position is not conserved among voltage-gated channels superfamily. We have shown that Y739D leads to significant changes in both fast and slow inactivation, whereas L1582P enhanced slow inactivation only. Steady-state fast inactivation for Y739D was shifted on 8.9 mV towards more negative potentials compare with that for WT, while L1582P did not enhanced fast inactivation (V1/2 WT: −62.8±1.7 mV; Y739D: −71.7±2.3 mV; L1582P: −58.7±1.4 mV). Slow inactivation was increased for both substitutions (INa (+20mV)/INa (−100mV) WT: 0.45±0.03; Y739D: 0,34±0.09: L1582P: 0.38±0.04). Steady-state fast inactivation Conclusions Both mutations, observed in patients with Brugada syndrome, influence on the slow inactivation process. Enhanced fast inactivation was shown only for Y739D mutant. The more dramatic alterations in sodium channel biophysical characteristics are likely linked with mutated residue conservativity. Acknowledgement/Funding RSF #17-15-01292

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Differential effects of cardiac sodium channel mutations on initiation of ventricular arrhythmias in patients with Brugada syndrome

Heart Rhythm ◽

10.1016/j.hrthm.2009.01.031 ◽

2009 ◽

Vol 6 (4) ◽

pp. 487-492 ◽

Cited By ~ 18

Author(s):

Hiroshi Morita ◽

Satoshi Nagase ◽

Daiji Miura ◽

Aya Miura ◽

Shigeki Hiramatsu ◽

...

Keyword(s):

Sodium Channel ◽

Brugada Syndrome ◽

Ventricular Arrhythmias ◽

Differential Effects ◽

Cardiac Sodium Channel

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A cardiac sodium channel mutation identified in Brugada syndrome associated with atrial standstill

Journal of Internal Medicine ◽

10.1046/j.0954-6820.2003.01247.x ◽

2004 ◽

Vol 255 (1) ◽

pp. 137-142 ◽

Cited By ~ 62

Author(s):

N. Takehara ◽

N. Makita ◽

J. Kawabe ◽

N. Sato ◽

Y. Kawamura ◽

...

Keyword(s):

Sodium Channel ◽

Brugada Syndrome ◽

Cardiac Sodium Channel ◽

Channel Mutation ◽

Sodium Channel Mutation

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Sodium channel kinetic changes that produce Brugada syndrome or progressive cardiac conduction system disease

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01025.2005 ◽

2007 ◽

Vol 292 (1) ◽

pp. H399-H407 ◽

Cited By ~ 33

Author(s):

Zhu-Shan Zhang ◽

Joseph Tranquillo ◽

Valentina Neplioueva ◽

Nenad Bursac ◽

Augustus O. Grant

Keyword(s):

Action Potential ◽

Sodium Channel ◽

Brugada Syndrome ◽

Sodium Current ◽

Conduction System ◽

Cardiac Conduction ◽

Cardiac Conduction System ◽

Wild Type ◽

System Disease ◽

Conduction System Disease

Some mutations of the sodium channel gene NaV1.5 are multifunctional, causing combinations of LQTS, Brugada syndrome and progressive cardiac conduction system disease (PCCD). The combination of Brugada syndrome and PCCD is uncommon, although they both result from a reduction in the sodium current. We hypothesize that slow conduction is sufficient to cause S-T segment elevation and undertook a combined experimental and theoretical study to determine whether conduction slowing alone can produce the Brugada phenotype. Deletion of lysine 1479 in one of two positively charged clusters in the III/IV inter-domain linker causes both syndromes. We have examined the functional effects of this mutation using heterologous expression of the wild-type and mutant sodium channel in HEK-293-EBNA cells. We show that ΔK1479 shifts the potential of half-activation, V1/2m, to more positive potentials ( V1/2m = −36.8 ± 0.8 and −24.5 ± 1.3 mV for the wild-type and ΔK1479 mutant respectively, n = 11, 10). The depolarizing shift increases the extent of depolarization required for activation. The potential of half-inactivation, V1/2h, is also shifted to more positive potentials ( V1/2h = −85 ± 1.1 and −79.4 ± 1.2 mV for wild-type and ΔK1479 mutant respectively), increasing the fraction of channels available for activation. These shifts are quantitatively the same as a mutation that produces PCCD only, G514C. We incorporated experimentally derived parameters into a model of the cardiac action potential and its propagation in a one dimensional cable (simulating endo-, mid-myocardial and epicardial regions). The simulations show that action potential and ECG changes consistent with Brugada syndrome may result from conduction slowing alone; marked repolarization heterogeneity is not required. The findings also suggest how Brugada syndrome and PCCD which both result from loss of sodium channel function are sometimes present alone and at other times in combination.

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