Pharmacological activation of normal and arrhythmia-associated mutant KCNQ1 potassium channels
Pharmacological activation of normal and arrhythmia-associated mutant KCNQ1 potassium channels
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DOI：
10.1161/01.res.0000102866.67863.2b
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发表时间：
2003-11-14
影响因子：
20.1
通讯作者：
Sanguinetti, MC
中科院分区：
文献类型：
--
作者：
Seebohm, G;Pusch, M;Sanguinetti, MC
KCNQ 1 α亚基与KCNE 1 β亚基共组装形成通道，传导对心脏动作电位复极化很重要的缓慢延迟整流钾电流（I-Ks）。KCNQ 1的突变减少了I-Ks并导致长QT综合征，这是一种心室复极障碍，易使受影响的个体发生心律失常和猝死。目前对长QT综合征的治疗是不够的。R-L3是一种苯二氮卓类药物，可激活I-Ks，并有可能提供基因特异性治疗。在本研究中，我们描述了R-L3与KCNQ 1通道相互作用的分子决定因素，使用计算机建模提出药物诱导的通道门控变化的机制，并确定其对几种长QT综合征相关突变KCNQ 1通道的影响异源表达在非洲爪蟾卵母细胞中。扫描突变结合电压钳分析表明，R-L3与位于KCNQ 1亚基第5和第6跨膜结构域的特异性残基相互作用。大多数KCNQ 1突变通道对R-L3的反应与野生型通道相似，但有一个突变通道（G306 R）对R-L3不敏感，可能是因为它破坏了药物结合位点的关键组分。
KCNQ1alpha-subunits coassemble with KCNE1 beta-subunits to form channels that conduct the slow delayed rectifier K+ current (I-Ks) important for repolarization of the cardiac action potential. Mutations in KCNQ1 reduce I-Ks and cause long-QT syndrome, a disorder of ventricular repolarization that predisposes affected individuals to arrhythmia and sudden death. Current therapy for long-QT syndrome is inadequate. R-L3 is a benzodiazepine that activates I-Ks and has the potential to provide gene-specific therapy. In the present study, we characterize the molecular determinants of R-L3 interaction with KCNQ1 channels, use computer modeling to propose a mechanism for drug-induced changes in channel gating, and determine its effect on several long-QT syndrome-associated mutant KCNQ1 channels heterologously expressed in Xenopus oocytes. Scanning mutagenesis combined with voltage-clamp analysis indicated that R-L3 interacts with specific residues located in the 5th and 6th transmembrane domains of KCNQ1 subunits. Most KCNQ1 mutant channels responded to R-L3 similarly to wild-type channels, but one mutant channel (G306R) was insensitive to R-L3 possibly because it disrupted a key component of the drug-binding site.