Characterization of a novel SCN5A mutation associated with Brugada syndrome reveals involvement of DIIIS4–S5 linker in slow inactivation

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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Characterization of repolarization in Brugada syndrome patients during exercise testing: Dynamic angle evaluation

Journal of Electrocardiology ◽

10.1016/j.jelectrocard.2015.06.008 ◽

2015 ◽

Vol 48 (5) ◽

pp. 879-886 ◽

Cited By ~ 2

Author(s):

Thomas Pospiech ◽

Jérémie Jaussaud ◽

Frédéric Sacher ◽

Darren A. Hooks ◽

Michel Haïssaguerre ◽

...

Keyword(s):

Exercise Testing ◽

Brugada Syndrome ◽

Dynamic Angle

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Characterization of the epicardial substrate for catheter ablation of Brugada syndrome

Heart Rhythm ◽

10.1016/j.hrthm.2016.07.025 ◽

2016 ◽

Vol 13 (11) ◽

pp. 2151-2158 ◽

Cited By ~ 47

Author(s):

Pei Zhang ◽

Roderick Tung ◽

Zuwen Zhang ◽

Xia Sheng ◽

Qiang Liu ◽

...

Keyword(s):

Catheter Ablation ◽

Brugada Syndrome

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Abstract 5676: Elevated Oxidative Stress is Associated with Ventricular Fibrillation Episode in Patients with Brugada Syndrome without SCN5A Mutation

Circulation ◽

10.1161/circ.118.suppl_18.s_982-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Masamichi Tanaka ◽

Keiko Ohgou ◽

Koji Nakagawa ◽

Takeshi Tada ◽

Masato Murakami ◽

...

Keyword(s):

Oxidative Stress ◽

Risk Factor ◽

Ventricular Fibrillation ◽

Brugada Syndrome ◽

Endomyocardial Biopsy ◽

Heart Diseases ◽

Multivariable Analysis ◽

Pathophysiological Mechanism ◽

Normal Heart ◽

Scn5a Mutation

Background; Brugada Syndrome (BS) is a disease known to cause ventricular fibrillation (VF) with structurally normal heart. Gene mutation (i.e. SCN5A) has been proposed to be related to the development of BS and VF. However, the pathophysiological mechanism associated with VF development without SCN5A mutation has not been studied yet. Oxidative stress is a common disorder that is related to many heart diseases. We have previously demonstrated that oxidative stress is closely linked to the arrhythmic development. Accordingly, we examined 4-hydroxy-2-nonenal (HNE) modified protein, which is a common mediator of oxidative stress in the myocardium, and VF episodes in patients with BS. Methods; We collected sixty-eight BS patients that underwent right ventricular endomyocardial biopsy (66 males, 2 female; mean age 49.0±11.6 years old). VF was documented in 11 and SCN5A mutation was detected in 14 patients. Biopsy samples were processed for histology [Masson’s trichrome staining for fibrosis, immuno staining for CD45, CD68, and HNE modified protein]. All results from histology were compared with VF episodes. We also performed the analysis in VF patients with (n=14) or without SCN5A mutations (n=54). Results: HNE positive area was significantly larger in VF patients [VF(+): 16.3±10.5, VF(−): 9.3±5.7%: P=0.029]. All other parameters (fibrosis area, CD45, and CD68) were not different between the groups. In multivariable analysis, HNE positive area was most important risk factor of VF development in patients without SCN5A mutation (P=0.004). Conclusions ; These data suggested that oxidative stress is associated with VF development in BS patients, especially in patients without SCN5A mutation.

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Ventricular fibrillation in Graves disease reveals a rare SCN5A mutation with W1191X variant associated with Brugada syndrome

HeartRhythm Case Reports ◽

10.1016/j.hrcr.2020.11.010 ◽

2020 ◽

Author(s):

Kristin Stawiarski ◽

John-Ross D. Clarke ◽

Ari Pollack ◽

Robert Winslow ◽

Sachin Majumdar

Keyword(s):

Ventricular Fibrillation ◽

Brugada Syndrome ◽

Graves Disease ◽

Scn5a Mutation

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Abstract 14356: Blood Tests That Improve the Accuracy of a Brugada Syndrome Diagnosis

Circulation ◽

10.1161/circ.132.suppl_3.14356 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Anyu Zhou ◽

Ning Jinag ◽

Marco Denegri ◽

An Xie ◽

Guangbin Shi ◽

...

Keyword(s):

Gene Expression ◽

Mrna Expression ◽

Brugada Syndrome ◽

Roc Analysis ◽

White Blood Cells ◽

Control Group ◽

Mrna Levels ◽

Operating Characteristics ◽

Optimal Cutoff ◽

Scn5a Mutation

Objectives: To discover the role of altered gene expression regulation in Brugada Syndrome (BrS) and to find biomarkers for BrS diagnosis. Methods: Twenty-five control patients (Control), 25 BrS patients without SCN5A mutation (SCN5A(-)) and 20 BrS patients with SCN5A mutation (SCN5A(+)) were included in this study. Specified gene expression of white blood cells (WBC) were measured by RT-qPCR using TaqMan® Gene Expression assay. Results: MEF2C and MESP1 are the two major cardiac specific transcription factors expressed in WBC. The mRNA expression levels of SCN5A, MEF2C and HuR, one of mRNA stabilizers, were decreased in the SCN5A (+) group (P=0.047, 0.02, 0.000 vs. control group, respectively). The mRNA expression of MESP1 in WBCs was significantly lower in both SCN5A(-) (P=0.012 vs. control) and SCN5A(+) (P=0.000 vs. control) groups. There was no difference between the two BrS groups in MESP1 expression (P=0.215). The area under the Receiver Operating Characteristics (ROC) analysis curve for prediction of BrS using MESP1 levels was 0.775 (95% CI 0.668, 0.882, asymptotic Sig.=0.000). At the optimal cutoff, the corresponding maximum sensitivity and specificity were 0.62 (95% CI: 0.47, 0.76) and 0.88 (0.69, 0.97), respectively. The diagnostic odds ratio (DOR) of MESP1 for BrS diagnosis was 11.96 (95% CI: 5.79, 24.73). The assessment of the mRNA levels in blood SCN5A, MEF2C and HuR were useful for predicting BrS patients with an SCN5A mutation. The area under the ROC analysis curve for prediction of BrS with an SCN5A mutation using SCN5A, MEF2C and HuR mRNA levels in WBCs was 0.847 (95% CI 0.752, 0.942, asymptotic Sig.=0.000), 0.685 (95% CI 0.542, 0.828, asymptotic Sig.=0.016) and 0.777 (95% CI 0.652, 0.902, asymptotic Sig.=0.000), respectively. At the optimal cutoff, the DOR of SCN5A, MEF2C and HuR for SCN5A(+) BrS diagnosis was 17.5 (95% CI: 8.06, 37.86), 4.9 (95% CI: 2.61, 9.17) and 23.5 (95% CI: 9.39, 58.80), respectively. Conclusions: Our results suggest that assessment of circulating MESP1 may be used as a biomarker for BrS diagnosis while decreased SCN5A, MEF2C and HuR mRNA in WBCs is associated with BrS patients with an SCN5A mutation. Our results also suggest that decreased expression of SCN5A, MEF2C, MESP1, and HuR may be pathophysiologically related to BrS.

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