Two novel Brugada syndrome-associated mutations increase KV4.3 membrane expression and function.
Two novel Brugada syndrome-associated mutations increase KV4.3 membrane expression and function.
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DOI：
10.3892/ijmm.2015.2223
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发表时间：
2015-07
影响因子：
5.4
通讯作者：
Xu H
中科院分区：
文献类型：
--
作者：
You T;Mao W;Cai B;Li F;Xu H
人心脏快速瞬时外向钾通道由KCND 3编码的KV4.3 α亚基和钾通道相互作用蛋白2（KChIP 2）β亚基组成，决定动作电位（AP）的早期复极。KV4.3中的两个人类突变（G600 R和L450 F）与Brugada综合征相关，它们增加KV4.3/KChIP 2编码的快速瞬时外向K+电流（Ito，f）并导致AP圆顶的稳定丧失。然而，这两个突变获得Ito，f功能的详细机制在很大程度上是未知的。本研究旨在探讨这些突变的影响及其机制。在表达KV4.3野生型（WT）和KV4.3突变体的HEK-293细胞中用KChIP 2进行全细胞膜片钳记录。这两个单独的mu基因编码的电流显着增加，但受两种突变影响的通道的动力学是不同的。这两个突变减缓了KV4.3/KChIP 2编码的通道失活;它们没有增加从KV4.3/KChIP 2编码的通道失活的恢复。Western印迹显示，总KV4.3蛋白在HEK-293细胞中显著增加，所述HEK-293细胞表达具有KChIP 2的两个单独突变体。此外，免疫荧光共聚焦显微镜表明，KV4.3通道蛋白表达更多的细胞膜相比，细胞质中表达的个别突变体与KChIP 2。此外，KChIP 2增加细胞膜中的通道蛋白的量的KV4.3突变体显着超过KV4.3-WT。逆转录-聚合酶链反应显示，KChIP 2的存在下，KV4.3 mRNA没有显着改变的个别突变。综上所述，本研究揭示了突变通过增加膜蛋白表达和减缓通道失活引起KV4.3/KChIP 2编码通道的功能获得。
The human cardiac fast transient outward K+ channel is composed of the KV4.3 α subunit encoded by KCND3 and the K+ channel-interacting protein 2 (KChIP2) β subunit, and determines the early repolarization of the action potential (AP). Two human mutations (G600R and L450F) in KV4.3 are associated with Brugada syndrome and they increase the KV4.3/KChIP2-encoded fast transient outward K+ current (Ito,f) and cause the stable loss of the AP dome. However, the detailed mechanisms underlying the gain of Ito,f function by these two mutations are largely unknown. The experiments in the present study were undertaken to investigate the effect of these mutations and the underlying mechanism. Whole cell patch-clamp recording was performed in HEK-293 cells expressing KV4.3-wild-type (WT) and KV4.3 mutants with KChIP2. The two individual mutant-encoded currents were significantly increased but the kinetics of the channels affected by the two mutations were different. The two mutations slowed KV4.3/KChIP2-encoded channel inactivation; they did not increase the recovery from the KV4.3/KChIP2-encoded channel inactivation. Western blotting showed that total KV4.3 protein was significantly augmented in HEK-293 cells expressing the two individual mutants with KChIP2. Furthermore, immunofluorescence confocal microscopy demonstrated that the KV4.3 channel protein was expressed more in the cell membrane compared to the cytoplasm in cells that expressed individual mutants with KChIP2. Also, KChIP2 increased the amount of channel protein in the cell membrane of KV4.3 mutants significantly more than KV4.3-WT. Reverse transcription-polymerase chain reaction showed that KV4.3 mRNA was not significantly changed by individual mutations in the presence of KChIP2. Taken together, the present study revealed that the mutations cause a gain-of-function of KV4.3/KChIP2-encoded channels by increasing membrane protein expression and slowing channel inactivation.
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影响因子：
1.3
作者：
Antzelevitch, C
通讯作者：
Antzelevitch, C
影响因子：
5
作者：
Singarayar, S;Singleton, C;Campbell, T
通讯作者：
Campbell, T
影响因子：
8.4
作者：
Delpon, Eva;Cordeiro, Jonathan M.;Antzelevitch, Charles
通讯作者：
Antzelevitch, Charles
影响因子：
5.5
作者：
Giudicessi, John R.;Ye, Dan;Tester, David J.;Crotti, Lia;Mugione, Alessandra;Nesterenko, Vladislav V.;Albertson, Richard M.;Antzelevitch, Charles;Schwartz, Peter J.;Ackerman, Michael J.
通讯作者：
Ackerman, Michael J.
影响因子：
5.5
作者：
Antzelevitch, C
通讯作者：
Antzelevitch, C