Arrhythmogenic Biophysical Phenotype for SCN5A Mutation S1787N Depends upon Splice Variant Background and Intracellular Acidosis.
Arrhythmogenic Biophysical Phenotype for SCN5A Mutation S1787N Depends upon Splice Variant Background and Intracellular Acidosis.
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DOI：
10.1371/journal.pone.0124921
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Makielski JC
中科院分区：
文献类型：
--
作者：
Hu RM;Tan BH;Tester DJ;Song C;He Y;Dovat S;Peterson BZ;Ackerman MJ;Makielski JC
SCN5A是3型长QT综合征、Brugada综合征和婴儿猝死综合征的易感基因。突变的SCN5A引起的Na功能障碍可能取决于其表达的剪接变异背景，也取决于酸中毒等环境因素。S1787N先前被报道为LQT3相关突变，在295名健康白人对照组中也观察到1例。在这里，我们测定了SCN5A-S1787N的体外生物物理表型，以努力进一步评估其可能的致病性。我们在两种最常见的选择性剪接的SCN5A异构体中设计了S1787N，主要的异构体在1077位缺少谷氨酰胺(Q1077del)，次要的异构体含有Q1077，并在HEK293细胞中表达了这两种工程构建物，用于电生理研究。用标准的全细胞膜片钳技术检测24小时后宏观电压门控性钠电流的变化。我们应用了pH值为7.4或6.7的细胞内溶液。在Q1077背景中的S1787N具有WT样的I-Na，包括峰值I-Na密度、活化和失活参数，以及在pH 7.4和pH 6.7的晚期I-Na幅度。然而，在Q1077del背景中有S1787N，与WT相比，在pH 7.4时I-Na的迟峰百分比增加了2.1倍，在pH 6.7时增加了2.9倍。S1787N的LQT3样生物物理表型取决于SCN5A剪接变异体和细胞内pH。这些发现进一步证明，剪接变异体和环境因素影响心脏SCN5A编码的钠通道(NaV1.5)的分子表型，对临床表型有意义，并可能为研究酸中毒引起的心律失常机制提供依据。
SCN5A is a susceptibility gene for type 3 long QT syndrome, Brugada syndrome, and sudden infant death syndrome. I Na dysfunction from mutated SCN5A can depend upon the splice variant background in which it is expressed and also upon environmental factors such as acidosis. S1787N was reported previously as a LQT3-associated mutation and has also been observed in 1 of 295 healthy white controls. Here, we determined the in vitro biophysical phenotype of SCN5A-S1787N in an effort to further assess its possible pathogenicity. We engineered S1787N in the two most common alternatively spliced SCN5A isoforms, the major isoform lacking a glutamine at position 1077 (Q1077del) and the minor isoform containing Q1077, and expressed these two engineered constructs in HEK293 cells for electrophysiological study. Macroscopic voltage-gated I Na was measured 24 hours after transfection with standard whole-cell patch clamp techniques. We applied intracellular solutions with pH7.4 or pH6.7. S1787N in the Q1077 background had WT-like I Na including peak I Na density, activation and inactivation parameters, and late I Na amplitude in both pH 7.4 and pH 6.7. However, with S1787N in the Q1077del background, the percentages of I Na late/peak were increased by 2.1 fold in pH 7.4 and by 2.9 fold in pH 6.7 when compared to WT. The LQT3-like biophysical phenotype for S1787N depends on both the SCN5A splice variant and on the intracellular pH. These findings provide further evidence that the splice variant and environmental factors affect the molecular phenotype of cardiac SCN5A-encoded sodium channel (Nav1.5), has implications for the clinical phenotype, and may provide insight into acidosis-induced arrhythmia mechanisms.
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