Requirement of βsubunit for the reduced voltage-gated Na+ current of a Brugada syndrome patient having novel double missense mutation (p.A385T/R504T) of SCN5A
10.4196/kjpp.2024.28.4.313
- Author:
Na Kyeong PARK
1
;
Seong Woo CHOI
;
Soon-Jung PARK
;
JooHan WOO
;
Hyun Jong KIM
;
Woo Kyung KIM
;
Sung-Hwan MOON
;
Hun-Jun PARK
;
Sung Joon KIM
Author Information
1. Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea
- Publication Type:Original Article
- From:The Korean Journal of Physiology and Pharmacology
2024;28(4):313-322
- CountryRepublic of Korea
- Language:EN
-
Abstract:
Mutations within the SCN5A gene, which encodes the α-subunit 5 (NaV1.5) of the voltage-gated Na+ channel, have been linked to three distinct cardiac arrhythmia disorders: long QT syndrome type 3, Brugada syndrome (BrS), and cardiac conduction disorder. In this study, we have identified novel missense mutations (p.A385T/R504T) within SCN5A in a patient exhibiting overlap arrhythmia phenotypes. This study aims to elucidate the functional consequences of SCN5A mutants (p.A385T/R504T) to understand the clinical phenotypes. Whole-cell patch-clamp technique was used to analyze the NaV1.5 current (INa) in HEK293 cells transfected with the wild-type and mutant SCN5A with or without SCN1B co-expression. The amplitude of INa was not altered in mutant SCN5A (p.A385T/R504T) alone. Furthermore, a rightward shift of the voltage-dependent inactivation and faster recovery from inactivation was observed, suggesting a gain-of-function state. Intriguingly, the coexpression of SCN1B with p.A385T/R504T revealed significant reduction of INa and slower recovery from inactivation, consistent with the loss-of-function in Na+ channels. The SCN1B dependent reduction of INa was also observed in a single mutation p.R504T, but p.A385T co-expressed with SCN1B showed no reduction. In contrast, the slower recovery from inactivation with SCN1B was observed in A385T while not in R504T. The expression of SCN1B is indispensable for the electrophysiological phenotype of BrS with the novel double mutations; p.A385T and p.R504T contributed to the slower recovery from inactivation and reduced current density of NaV1.5, respectively.
