In vitro molecular interactions and distribution of KCNE family with KCNQ1 in the human heart
In vitro molecular interactions and distribution of KCNE family with KCNQ1 in the human heart
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DOI：
10.1016/j.cardiores.2005.02.014
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发表时间：
2005-08-15
影响因子：
10.8
通讯作者：
Barhanin, J
中科院分区：
文献类型：
--
作者：
Bendahhou, S;Marionneau, C;Barhanin, J
目的：电压门控性K+通道KCNQ1与KCNE1β小亚基结合，构成心脏LKS复极电流的基础。根据序列同源性，KCNE家族被认为由五个成员组成。有争议的数据表明它们参与了几个K+通道蛋白复合体，包括KCNQ1。KCNE不同亚基在人类心脏中的表达水平和可能的功能仍有待进一步研究。方法：我们利用膜片钳技术在哺乳动物细胞中对KCNE和KCNQ1的所有亚基进行了比较研究。结果：KCNQ1/KCNE1异位多聚体电流密度高，门控动力学慢，电压依赖性强，KCNQ1/KCNE2和KCNQ1/KCNE3复合体分别产生低电流密度和高电流密度的瞬时电压依赖性电流。KCNE4或KCNE5与KCNQ1共表达可在生理电压范围内诱发小电流，其动力学与KCNQ1/KCNE1复合体相似。然而，这些抑制亚基与疾病相关突变(S140G-KCNQ1)的共表达导致了几乎无法与KCNQ1/KCNE1规范复合体区分的电流。绝对定量分析显示，除KCNE4外，其余各转录本在左心房内、左室壁心内膜和心外膜内的分布相对均匀，丰度如下：KCNQ1>；>；KCNE4>；=KCNE1>；KCNE3>；KCNE2>；KCNE5。结论：在人体心脏中，KCNQ1以一种特定的方式与5个KCNE亚基形成通道复合体，但只有与KCNE1、KCNE2和KCNE3的相互作用可能具有生理意义。(C)2005年欧洲心脏病学会。爱思唯尔出版，版权所有。
Objective: The voltage-gated K+ channel KCNQ1 associates with the small KCNE1 beta subunit to underlie the lKs repolarizing current in the heart. Based on sequence homology, the KCNE family is recognized to comprise five members. Controversial data have indicated their participation in several K+ channel protein complexes, including KCNQ1. The expression level and the putative functions of the different KCNE subunits in the human heart still require further investigation.Methods: We have carried out a comparative study of all KCNE subunits with KCNQ1 using the patch-clamp technique in mammalian cells. Real-time RT-PCR absolute quantification was performed on human atrial and ventricular tissue.Results: While KCNQ1/KCNE1 heteromultimer reached high current density with slow gating kinetics and pronounced voltage dependence, KCNQ1/KCNE2 and KCNQ1/KCNE3 complexes produced instantaneous voltage-independent currents with low and high current density, respectively. Co-expression of KCNE4 or KCNE5 with KCNQ1 induced small currents in the physiological range of voltages, with kinetics similar to those of the KCNQ1/KCNE1 complex. However, co-expression of these inhibitory subunits with a disease-associated mutation (S140G-KCNQ1) led to currents that were almost undistinguishable from the KCNQ1/KCNE1 canonical complex. Absolute cDNA quantification revealed a relatively homogeneous distribution of each transcript, except for KCNE4, inside left atria and endo- and epicardia of left ventricular wall with the following abundance: KCNQ1 >> KCNE4 >= KCNE1 > KCNE3 >KCNE2>KCNE5. KCNE4 expression was twice as high in atrium compared to ventricle.Conclusions: Our data show that KCNQ1 forms a channel complex with 5 KCNE subunits in a specific manner but only interactions with KCNE1, KCNE2, and KCNE3 may have physiological relevance in the human heart. (C) 2005 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.