Dominant-Negative Control of cAMP-Dependent IKs Upregulation in Human Long-QT Syndrome Type 1
Dominant-Negative Control of cAMP-Dependent IKs Upregulation in Human Long-QT Syndrome Type 1
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DOI：
10.1161/circresaha.111.249482
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发表时间：
2012-01-20
影响因子：
20.1
通讯作者：
Volders, Paul G. A.
中科院分区：
文献类型：
--
作者：
Heijman, Jordi;Spatjens, Roel L. H. M. G.;Volders, Paul G. A.
基本原理：KCNQ 1（缓慢激活的延迟整流钾离子（I-Ks）通道的α-亚基）S6跨膜片段中的突变A341 V易导致严重的长QT 1综合征，伴交感神经触发的室性快速性心律失常和心源性猝死。目的：在A341 V患者中已经确定了几种遗传风险修饰因子，但明显复极表型的分子机制，特别是在β-肾上腺素能受体刺激期间，仍然不清楚。我们的目的是阐明这些机制，并提供新的见解控制cAMP依赖性调制的I-Ks.方法和结果：我们的特点是A341 V的影响，在转染中国仓鼠卵巢细胞的I-Ks大分子通道复合物，并发现一个显性负抑制cAMP依赖Yotiao介导的I-Ks上调的基础电流的显性负减少。用天冬氨酸模拟磷酸取代N末端位置S27可以挽救这种上调的丧失。蛋白质印迹分析显示，即使对于杂合子A341 V，KCNQ 1在S27处的磷酸化也减少，这表明某些（突变型）KCNQ 1亚基的磷酸化缺陷可以完全抑制I-Ks的上调。杂合KCNQ 1 WT：G589 D和杂合KCNQ 1 WT：S27 A（磷酸化惰性取代）的功能分析也显示了这种抑制。Yotiao与KCNQ 1-A341 V（在KCNE 1的存在下）的免疫沉淀与wild-type.Conclusions没有不同：我们的研究结果表明，参与的KCNQ 1-S6区域在/或周围A341 cAMP依赖性刺激的I-Ks，一个过程，是在强烈的显性负控制，这表明四聚体KCNQ 1磷酸化是必需的。特定的长QT 1突变，包括杂合子A341 V，使这种调节失效。(Circ Res. 2012;110：211-219）。
Rationale: The mutation A341V in the S6 transmembrane segment of KCNQ1, the alpha-subunit of the slowly activating delayed-rectifier K+ (I-Ks) channel, predisposes to a severe long-QT1 syndrome with sympathetic-triggered ventricular tachyarrhythmias and sudden cardiac death.Objective: Several genetic risk modifiers have been identified in A341V patients, but the molecular mechanisms underlying the pronounced repolarization phenotype, particularly during beta-adrenergic receptor stimulation, remain unclear. We aimed to elucidate these mechanisms and provide new insights into control of cAMP-dependent modulation of I-Ks.Methods and Results: We characterized the effects of A341V on the I-Ks macromolecular channel complex in transfected Chinese hamster ovary cells and found a dominant-negative suppression of cAMP-dependent Yotiao-mediated I-Ks upregulation on top of a dominant-negative reduction in basal current. Phosphomimetic substitution of the N-terminal position S27 with aspartic acid rescued this loss of upregulation. Western blot analysis showed reduced phosphorylation of KCNQ1 at S27, even for heterozygous A341V, suggesting that phosphorylation defects in some (mutant) KCNQ1 subunits can completely suppress I-Ks upregulation. Functional analyses of heterozygous KCNQ1 WT:G589D and heterozygous KCNQ1 WT:S27A, a phosphorylation-inert substitution, also showed such suppression. Immunoprecipitation of Yotiao with KCNQ1-A341V (in the presence of KCNE1) was not different from wild-type.Conclusions: Our results indicate the involvement of the KCNQ1-S6 region at/or around A341 in cAMP-dependent stimulation of I-Ks, a process that is under strong dominant-negative control, suggesting that tetrameric KCNQ1 phosphorylation is required. Specific long-QT1 mutations, including heterozygous A341V, disable this regulation. (Circ Res. 2012;110:211-219.)