钠通道突变致短QT综合征的分子机制与个体化治疗初步探索

The genetics and electrophysiology pathogenesis of Short QT syndrome (SQTS) has not been fully elucidated, and the effective drugs of SQTS are still lacking . Preliminary research indicated that the sodium channel gene SCN5A mutations (E428G, V1951L) is closely associated with the onset of SQTS, but the specific mechanism is not clear. We speculate that the mutations change the electrophysiological characteristics and membrane transport process of sodium channel, which influence the function of sodium channel and cause SQTS. We will reveal the electrophysiological characteristics of mutated sodium channels through the methods of gene cloning, Induced mutagenesis,gene transfection and the whole cell patch technique.Through the immunofluorescence and cell membrane protein extraction technology to analyze the membrane transport process of mutated sodium channels and further reveal the molecular mechanisms of sodium channel mutations causing SQTS. At the same time, in vitro the drugs (propafenone, mexiletine and amiodarone,) will act on the mutated sodium channels and to evaluate the effective anti-arrhythmic drugs for SQTS. Through cotransfection of MOG1 protein (sodium channel regulatory protein, which can enhance the membrane transport process of mutated sodium channel in Brugada syndrome) and mutated sodium channels, to explore the "salvation" role of MOG1 protein to mutated sodium channels,and provide the clue and targets for the individualized treatment of SQTS.

目前短QT综合征（SQTS）遗传学及电生理发病机制尚未完全阐明，有效治疗药物缺乏。前期工作发现钠通道SCN5A基因突变（E428G、V1951L）与SQTS发病密切相关，但具体机制不明确。推测上述突变通过影响钠通道的电生理特性或通道蛋白膜转运过程，导致钠通道功能学改变和SQTS发生。我们将通过基因克隆、定点突变诱导、基因转染、全细胞膜片钳等技术，揭示突变对钠通道电生理特性的影响，结合免疫荧光、细胞膜蛋白分离技术，分析突变对钠通道蛋白膜转运功能作用，进一步阐述钠通道突变致SQTS的分子机制。同时在体外将药物（普罗帕酮、美西律和胺碘酮）作用于突变型钠通道，来筛选对突变通道具有“拯救作用”的抗心律失常药物。通过共转染MOG1蛋白（钠通道调节蛋白，能够增强Brugada综合征突变钠通道的膜转运功能）与突变钠通道，探索MOG1蛋白对突变通道的“拯救作用”，为SQT的个体化治疗提供思路和靶标。

目前短QT综合征（SQTS）遗传学及电生理发病机制尚未完全阐明，有效治疗药物缺乏。在此之前我们团队首次发现钠通道SCN5A基因突变（E428G、V1951L）与SQTS发病密切相关，但具体机制不明确。推测上述突变通过影响钠通道的电生理特性或通道蛋白膜转运过程，导致钠通道功能学改变和SQTS发生。课题组成员在本国家自然科学基金的指导和资助下，按照国家基金委管理条例和项目计划，严格实施并顺利完成课题研究内容。先后通过基因克隆、定点突变诱导、基因转染、全细胞膜片钳等技术，发现与野生型相比，SCN5A基因突变型（E428G、V1951L）钠离子通道电流密度明显增加，证实这两个突变为功能获得性突变；此外，与野生型相比，SCN5A突变（E428G、V1951L）钠通道SSA，SSI均显著增加，提示突变后钠离子通道的门控动力学改变。结合细胞膜蛋白分离技术和western blot技术分析突变对钠通道蛋白膜转运功能作用，发现SCN5A突变（E428G、V1951L) 钠通道在细胞膜上表达量增加。通过共转染MOG1蛋白发现MOG1蛋白对突变通道具有“拯救作用”。