D242N, a KV7.1 LQTS mutation uncovers a key residue for IKs voltage dependence
D242N, a KV7.1 LQTS mutation uncovers a key residue for IKs voltage dependence
复制标题
DOI：
10.1016/j.yjmcc.2017.07.009
复制
发表时间：
2017-09-01
影响因子：
5
通讯作者：
Valenzuela, Carmen
中科院分区：
文献类型：
--
作者：
Moreno, Cristina;Oliveras, Anna;Valenzuela, Carmen
K（V）7.1和KCNE 1共同组装产生I-KS电流，这是心脏动作电位最重要的复极化电流之一。在K（V）7.1和KCNE 1中发现了超过500个突变，至少有36个突变导致了长QT综合征（LQTS）。本研究的目的是表征与LQTS相关的D242 N K（V）7.1突变的生物物理和细胞后果。该突变位于S4跨膜段，在Kv7.1通道的电压传感器内，破坏了该区域的保守电荷平衡。穿孔膜片钳实验表明，出乎意料的是，突变没有破坏电压依赖性激活，但它消除了失活，并减缓了D242 N K（V）7.1通道的激活动力学。细胞表面蛋白的生物素化和免疫共沉淀实验表明，突变既不改变质膜靶向，也不改变K（V）7.1和KCNE 1之间的共组装。然而，D242 N K（V）7.1与KCNE 1的结合强烈地将激活的电压依赖性转移到更去极化的电位（+ 50 mV），阻碍了生理相关膜电位下的IKS电流。功能和计算分析表明，携带D242 N突变的LQTS患者的临床表型是由于对运动的动作电位适应受损，特别是心率增加。此外，我们的数据确定D242氨基酸位置作为参与KCNE 1介导的K（V）7.1通道激活的电压依赖性调节的潜在残基。(C)2017爱思唯尔有限公司版权所有
K(V)7.1 and KCNE1 co-assemble to give rise to the I-KS current, one of the most important repolarizing currents of the cardiac action potential. Its relevance is underscored by the identification of >500 mutations in K(V)7.1 and, at least, 36 in KCNE1, that cause Long QT Syndrome (LQTS). The aim of this study was to characterize the biophysical and cellular consequences of the D242N K(V)7.1 mutation associated with the LQTS. The mutation is located in the S4 transmembrane segment, within the voltage sensor of the Kv7.1 channel, disrupting the conserved charge balance of this region. Perforated patch-clamp experiments show that, unexpectedly, the mutation did not disrupt the voltage-dependent activation but it removed the inactivation and slowed the activation kinetics of D242N K(V)7.1 channels. Biotinylation of cell-surface protein and co-immunoprecipitation experiments revealed that neither plasma membrane targeting nor co-assembly between K(V)7.1 and KCNE1 was altered by the mutation. However, the association of D242N K(V)7.1 with KCNE1 strongly shifted the voltage dependence of activation to more depolarized potentials (+ 50 mV), hindering IKS current at physiologically relevant membrane potentials. Both functional and computational analysis suggest that the clinical phenotype of the LQTS patients carrying the D242N mutation is due to impaired action potential adaptation to exercise and, in particular, to increase in heart rate. Moreover, our data identify D242 aminoacidic position as a potential residue involved in the KCNE1-mediated regulation of the voltage dependence of activation of the K(V)7.1 channel. (C) 2017 Elsevier Ltd. All rights reserved.