快速激活延迟整流钾离子通道a亚基F129I突变致长QT综合征机制研究

Electrophysiological mechanism of KCNH2 causing IKr channel dysfunction in long QT syndrome

目的:通过对1例长QT综合征2型患者疑似致病突变KCNH2(F129I)细胞电生理学研究,探究其细胞电生理学发病机制。方法:采用目标区域捕获高深度测序技术进行候选基因突变筛查;以脂质体转染技术通过HEK293细胞表达可疑致病突变。应用全细胞膜片钳技术记录HERG通道电流。结果:候选基因测序发现KCNH2基因第385核苷酸位点T>A杂合子错义突变,导致第129位密码子由苯丙氨酸变为异亮氨酸(F129I),进一步细胞膜片钳研究发现F129I突变型IKr电流密度显著减小,峰值电流抑制率约为野生型的86%。共转染野生型与F129I结果显示IKr电流显著恢复,与野生型差异无统计学意义。结论:本研究通过细胞电生理学研究证实患者携带KCNH2(F129I)致LQT2发生机制为HERG转运障碍,导致IKr功能减弱。

Objective:The purpose of this study was to identify the electrophysiological mechanisms of a mutation fund inα1 subunit of rapid delayed rectifier potassium channel(IKr)of a proband with long QT syndrome.Methods:Candidate genes were screened by direct sequencing.Whole cell patch clamp analysis of the HEK293 cell with express the mutant channel was used to investigate the molecular and electrophysiological mechanism.Results:Sequence analysis of the coding region of the KCNH2 gene,identified a T to A heterozygous missense mutation at nucleotide site 385 that result ed in an amino acid substitution of phenylalanine to isoleucine in amino acid site 129(F129I).Patch clamp analysis showed that the F129I significantly reduced the current of IKr in transfected HEK293 cell,the reduction rate was almost 86%.The activation curve analysis between KCNH2(F129I)and wile type KCNH2 showed no difference in both the half-maximal activation(V1/2)and the slope value.Conclusions:We reported a case of KCNH2 mutation related to long QT syndrome in Chinese population,and the electrophysiological mechanism was IKr function reduced.