KvLQT1 modulates the distribution and biophysical properties of HERG -: A novel α-subunit interaction between delayed rectifier currents
KvLQT1 modulates the distribution and biophysical properties of HERG -: A novel α-subunit interaction between delayed rectifier currents
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DOI：
10.1074/jbc.m309087200
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发表时间：
2004-01-09
影响因子：
4.8
通讯作者：
Nattel, S
中科院分区：
文献类型：
--
作者：
Ehrlich, JR;Pourrier, M;Nattel, S
心脏复极受慢（I-Ks）和快（I-Kr）延迟整流电流的共同控制。实验和临床证据表明，这些组件之间的重要功能相互作用。我们假设KvLQT 1和I-Ks和I-Kr的HERG α亚基之间可能存在更直接的相互作用，并结合生物物理和生物化学技术对这一概念进行了测试。在哺乳动物表达系统中KvLQT 1与HERG的共表达通过增加快速组分的贡献（例如，在从+20 mV到-50 mV复极时：从20 +/-3至32 +/-5%，p < 0.05），在生理相关电位下显著加速HERG电流失活，使得HERG电流更像天然I-Kr。此外，通过与KvLQT 1共表达，HERG电流密度大约加倍（例如，在步进至+ 10 mV后的尾电流：18 +/-3对39 +/-7 pA/皮法，p < 0.01）。KvLQT 1共表达也使HERG的膜免疫定位增加了约2倍（p < 0.05）。HERG和KvLQT 1在犬心室肌细胞中共免疫定位，在培养的中国仓鼠卵巢细胞以及天然心脏组织中共免疫沉淀，表明HERG和KvLQT 1蛋白在体外和体内之间的物理相互作用。蛋白质相互作用试验也证明了KvLQT 1（而不是另一个K+通道α亚基，Kv3.4）与C-末端HERG谷胱甘肽S-转移酶融合蛋白的结合。与HERG共表达不影响KvLQT 1的膜定位或离子电流特性。这项研究表明，I-Ks的α-亚基可以相互作用，并修改本地化和I-Kr的α-亚基的载流特性，提供了潜在的新的见解延迟整流电流系统的分子功能。
Cardiac repolarization is under joint control of the slow (I-Ks) and rapid (I-Kr) delayed rectifier currents. Experimental and clinical evidence indicates important functional interactions between these components. We hypothesized that there might be more direct interactions between the KvLQT1 and HERG alpha-subunits of I-Ks and I-Kr and tested this notion with a combination of biophysical and biochemical techniques. Co-expression of KvLQT1 with HERG in a mammalian expression system significantly accelerated HERG current deactivation at physiologically relevant potentials by increasing the contribution of the fast component (e.g. upon repolarization from +20 mV to -50 mV: from 20 +/- 3 to 32 +/- 5%, p < 0.05), making HERG current more like native I-Kr. In addition, HERG current density was approximately doubled (e.g. tail current after a step to + 10 mV: 18 +/- 3 versus 39 +/- 7 pA/ picofarad, p < 0.01) by co-expression with KvLQT1. KvLQT1 co-expression also increased the membrane immunolocalization of HERG by similar to2-fold ( p < 0.05). HERG and KvLQT1 co-immunolocalized in canine ventricular myocytes and co-immunoprecipitated in cultured Chinese hamster ovary cells as well as in native cardiac tissue, indicating physical interactions between HERG and KvLQT1 proteins in vitro and in vivo. Protein interaction assays also demonstrated binding of KvLQT1 ( but not another K+ channel alpha-subunit, Kv3.4) to a C-terminal HERG glutathione S-transferase fusion protein. Co-expression with HERG did not affect the membrane localization or ionic current properties of KvLQT1. This study shows that the alpha-subunit of I-Ks can interact with and modify the localization and current-carrying properties of the alpha-subunit of I-Kr, providing potentially novel insights into the molecular function of the delayed rectifier current system.