Mutant caveolin-3 induces persistent late sodium current and is associated with long-QT syndrome
Mutant caveolin-3 induces persistent late sodium current and is associated with long-QT syndrome
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DOI：
10.1161/circulationaha.106.635268
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发表时间：
2006-11-14
期刊：
影响因子：
37.8
通讯作者：
Towbin, Jeffrey A.
中科院分区：
文献类型：
--
作者：
Vatta, Matteo;Ackerman, Michael J.;Towbin, Jeffrey A.
背景-先天性长qt综合征（LQTS）是一种由心脏复极紊乱引起的原发性心律失常综合征。LQTS影响约1 / 3000人，是年轻人尸检阴性猝死的最常见原因之一。自1995年在LQTS中发现心脏通道基因突变以来，已鉴定出8个LQTS易感基因的数百个突变。所有8种LQTS基因型都代表原发性心脏通道缺陷（即离子通道病变），除了LQT4，它是由于锚蛋白b突变引起的功能性通道病变。大约25%的LQTS在病理上仍无法解释。我们追求“最终共同途径”假说，以引出新的lqts易感基因。根据最近的观察，lqt3相关的scn5a编码的心脏钠通道定位于小窝，这是已知的膜微结构域，其横纹肌中的主要成分是小窝蛋白-3，我们假设小窝蛋白-3的突变可能代表了LQTS的一种新的发病机制。方法和结果：利用聚合酶链反应、变性高效液相色谱和直接DNA测序，我们对905例进行LQTS基因检测的无亲缘关系患者的CAV3进行了开放阅读框/剪接位点突变分析。通过定点诱变和瞬时异源表达确定的分子表型，将CAV3突变改造成稳定表达心脏钠通道hNa(v)1.5的细胞系。我们在cav3编码的小洞蛋白-3中发现了4个新的突变，这些突变在bb101000个对照等位基因中是不存在的。在稳定表达hNav1.5并瞬时转染野生型和突变型caveolin-3的HEK293细胞中，对钠电流的电生理分析表明，突变型caveolin-3导致晚期钠电流比野生型caveolin-3增加2- 3倍。我们的观察结果与lqt3相关的SCN5A突变相关的晚期钠电流增加相似。结论：本研究报告了LQTS患者的第一个CAV3突变，我们提供的功能数据证明了晚期钠电流的功能获得性增加。
Background - Congenital long-QT syndrome (LQTS) is a primary arrhythmogenic syndrome stemming from perturbed cardiac repolarization. LQTS, which affects approximate to 1 in 3000 persons, is 1 of the most common causes of autopsy-negative sudden death in the young. Since the sentinel discovery of cardiac channel gene mutations in LQTS in 1995, hundreds of mutations in 8 LQTS susceptibility genes have been identified. All 8 LQTS genotypes represent primary cardiac channel defects (ie, ion channelopathy) except LQT4, which is a functional channelopathy because of mutations in ankyrin-B. Approximately 25% of LQTS remains unexplained pathogenetically. We have pursued a "final common pathway" hypothesis to elicit novel LQTS-susceptibility genes. With the recent observation that the LQT3-associated, SCN5A-encoded cardiac sodium channel localizes in caveolae, which are known membrane microdomains whose major component in the striated muscle is caveolin-3, we hypothesized that mutations in caveolin-3 may represent a novel pathogenetic mechanism for LQTS.Methods and Results - Using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing, we performed open reading frame/splice site mutational analysis on CAV3 in 905 unrelated patients referred for LQTS genetic testing. CAV3 mutations were engineered by site-directed mutagenesis and the molecular phenotype determined by transient heterologous expression into cell lines that stably express the cardiac sodium channel hNa(v)1.5. We identified 4 novel mutations in CAV3-encoded caveolin-3 that were absent in > 1000 control alleles. Electrophysiological analysis of sodium current in HEK293 cells stably expressing hNav1.5 and transiently transfected with wild-type and mutant caveolin-3 demonstrated that mutant caveolin-3 results in a 2- to 3-fold increase in late sodium current compared with wild-type caveolin-3. Our observations are similar to the increased late sodium current associated with LQT3-associated SCN5A mutations.Conclusions - The present study reports the first CAV3 mutations in subjects with LQTS, and we provide functional data demonstrating a gain-of-function increase in late sodium current.