Loss-of-function mutation of the SCN3B-encoded sodium channel β3 subunit associated with a case of idiopathic ventricular fibrillation
Loss-of-function mutation of the SCN3B-encoded sodium channel β3 subunit associated with a case of idiopathic ventricular fibrillation
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DOI：
10.1093/cvr/cvp417
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发表时间：
2010-06-01
影响因子：
10.8
通讯作者：
Makielski, Jonathan C.
中科院分区：
文献类型：
--
作者：
Valdivia, Carmen R.;Medeiros-Domingo, Argelia;Makielski, Jonathan C.
在不存在Brugada综合征表型的特发性心室颤动（IVF）中，已发现SCN 5A编码的钠通道SCN 5A或Nav1.5的功能丧失突变。Nav1.5受四个钠通道辅助β亚基调节。在此，我们报告了一例IVF患者，SCN 3B编码的钠通道β亚基Nav β 3中的一种新突变导致体外Nav1.5通道功能丧失，对KCNQ 1、KCNH 2、SCN 5A、KCNE 1、KCNE 2、GPD 1 L、四种钠通道β亚基基因（SCN 1 - 4 B）进行了全面的开放阅读框突变分析，并对RYR 2进行了靶向扫描。一种新的错义突变，Nav β 3-V54 G，在一名20岁的男性中被发现，他目睹了因VF导致的虚脱和除颤。心电图显示为S波，成像研究显示心脏结构正常。突变的残基在物种间高度保守，定位于Nav β 3细胞外结构域，并且在800个参考等位基因中不存在。我们发现HEK-293细胞具有内源性Nav β 3，但COS细胞没有。与WT相比，在HEK-293细胞和COS细胞中Nav1.5与Nav β 3-V54 G的共表达（有或没有Nav β 1亚基的共表达）揭示了峰值钠电流的显著降低和失活的正移位。免疫共沉淀实验显示Nav β 3与Nav 1. 5结合，免疫细胞化学显示Nav β 3-V54 G共表达后，细胞膜转运能力显著降低。本研究为Nav β 3突变可能导致IVF提供了分子和细胞学证据。
Loss-of-function mutations in the SCN5A-encoded sodium channel SCN5A or Nav1.5 have been identified in idiopathic ventricular fibrillation (IVF) in the absence of Brugada syndrome phenotype. Nav1.5 is regulated by four sodium channel auxiliary beta subunits. Here, we report a case with IVF and a novel mutation in the SCN3B-encoded sodium channel beta subunit Nav beta 3 that causes a loss of function of Nav1.5 channels in vitro.Comprehensive open reading frame mutational analysis of KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, GPD1L, four sodium channel beta subunit genes (SCN1-4B), and targeted scan of RYR2 was performed. A novel missense mutation, Nav beta 3-V54G, was identified in a 20-year-old male following witnessed collapse and defibrillation from VF. The ECG exhibited epsilon waves, and imaging studies demonstrated a structurally normal heart. The mutated residue was highly conserved across species, localized to the Nav beta 3 extracellular domain, and absent in 800 reference alleles. We found that HEK-293 cells had endogenous Nav beta 3, but COS cells did not. Co-expression of Nav1.5 with Nav beta 3-V54G (with or without co-expression of the Nav beta 1 subunit) in both HEK-293 cells and COS cells revealed a significant decrease in peak sodium current and a positive shift of inactivation compared with WT. Co-immunoprecipitation experiments showed association of Nav beta 3 with Nav1.5, and immunocytochemistry demonstrated a dramatic decrease in trafficking to the plasma membrane when co-expressed with mutant Nav beta 3-V54G.This study provides molecular and cellular evidence implicating mutations in Nav beta 3 as a cause of IVF.