Functional modulation of the transient outward current Ito by KCNE β-subunits and regional distribution in human non-failing and failing hearts
Functional modulation of the transient outward current Ito by KCNE β-subunits and regional distribution in human non-failing and failing hearts
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DOI：
10.1016/j.cardiores.2006.06.017
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发表时间：
2006-09-01
影响因子：
10.8
通讯作者：
Wettwer, Erich
中科院分区：
文献类型：
--
作者：
Radicke, Susanne;Cotella, Diego;Wettwer, Erich
目的：Kv4.3 (KCND3) 通道是人体心脏中瞬时外向电流 I 的基础，其功能可以通过几个辅助亚基（例如 KChIP2 和 KCNE1-KCNE5）进行调节。在这里，我们的目的是确定 Kv4.3、KChIP2 和 KCNE mRNA 在非衰竭和衰竭人类心脏中的区域表达，并研究异源表达系统中亚基共表达的功能后果。方法：我们实时定量了两种 Kv4.3 亚型 Kv4.3-S 和 Kv4.3-L、KChIP2 以及 KCNE1-KCNE5 的 mRNA 水平逆转录聚合酶链反应。我们还利用全细胞电压钳法研究了 KCNE 对 CHO 细胞中 Kv4.3 + KChIP2 电流特性的影响。结果：在非衰竭心脏中，KCNE1、KCNE3 和 KCNE5 低表达，KCNE2 表达高出 3 倍，KCNE4 高出 60 倍。仅在左心室和右心室中检测到 KChIP2 的透壁梯度。与非衰竭组织相比，衰竭心脏表现出较高的 Kv4.3-L 和 KCNE1 表达，以及较低的 Kv4.3-S、KChIP2、KCNE4 和 KCNE5 表达。在 CHO 细胞中，共表达的 KCNE 对 Kv4.3 + KChIP2 电流进行了差异性修改：KCNE1 和 KCNE3-5 的失活时间常数较短，而达峰时间缩短，并且所有 KCNE 亚基的稳态失活 V-0.5 均转移至更负的电位。重要的是，KCNE2 在从失活恢复过程中诱导了独特且显着的峰值电流“过冲”，类似于人类 I-to 所描述的情况，而其他 KCNE 亚基几乎没有诱导过冲 (KCNE4,5) 或没有过冲。结论：所有 KCNE 在转录本水平上都在人类心脏中表达。与它相比。在天然人类肌细胞中，KChIP2 和 KCNE 的组合均未在当前特征中产生理想的一致性，这表明其他因素有助于调节天然 I-to 通道。 (c) 2006 年欧洲心脏病学会。爱思唯尔出版 BY.所有紧身衣均保留。
Objectives: The function of Kv4.3 (KCND3) channels, which underlie the transient outward current I,, in human heart, can be modulated by several accessory subunits such as KChIP2 and KCNE1-KCNE5. Here we aimed to determine the regional expression of Kv4.3, KChIP2, and KCNE mRNAs in non-failing and failing human hearts and to investigate the functional consequences of subunit coexpression in heterologous expression systems.Methods: We quantified mRNA levels for two Kv4.3 isoforms, Kv4.3-S and Kv4.3-L, and for KChIP2 as well as KCNE1-KCNE5 with real-time RT-PCR. We also studied the effects of KCNEs on Kv4.3 + KChIP2 current characteristics in CHO cells with the whole-cell voltage-clamp method.Results: In non-failing hearts, low expression was found for KCNE1, KCNE3, and KCNE5, three times higher expression for KCNE2, and 60 times higher for KCNE4. Transmural gradients were detected only for KChIP2 in left and right ventricles. Compared to non-failing tissue, failing hearts showed higher expression of Kv4.3-L and KCNE1 and lower of Kv4.3-S, KChIP2, KCNE4, and KCNE5. In CHO cells, Kv4.3 + KChIP2 currents were differentially modified by co-expressed KCNEs: time constants of inactivation were shorter with KCNE1 and KCNE3-5 while time-to-peak was decreased, and V-0.5 of steady-state inactivation was shifted to more negative potentials by all KCNE subunits. Importantly, KCNE2 induced a unique and prominent 'overshoot' of peak current during recovery from inactivation similar to that described for human I-to while other KCNE subunits induced little (KCNE4,5) or no overshoot.Conclusions: All KCNEs are expressed in the human heart at the transcript level. Compared to It. in native human myocytes, none of the combination of KChIP2 and KCNE produced an ideal congruency in current characteristics, suggesting that additional factors contribute to the regulation of the native I-to channel. (c) 2006 European Society of Cardiology. Published by Elsevier BY. All tights reserved.