Characterization of the mouse ClC-K1/Barttin chloride channel

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• 作者：S¨¦bastien L'Hoste ; Alexei Diakov ; Olga Andrini ; Mathieu Genete ; Laurent Pinelli ; Teddy Gr ; Mathilde Keck ; Marc Paulais ; Laurent Beck ; Christoph Korbmacher ; Jacques Teulon ; St¨¦phane Lourdel
• 关键词：CCD ; cortical collecting duct ; ClC-K ; kidney chloride channel ; CNT ; connecting tubule ; CTAL ; cortical thick ascending limb ; DCT ; distal convoluted tubule ; DIDS ; 4 ; 4&prime ; -diisothiocyanato-2 ; 2&prime ; -stilbene disulfonic acid disodium salt ; DPC ; 2-(phenyla
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：1828
• 期：11
• 页码：2399-2409
• 全文大小：1348 K

文摘

Several Cl^? channels have been described in the native renal tubule, but their correspondence with ClC-K1 and ClC-K2 channels (orthologs of human ClC-Ka and ClC-Kb), which play a major role in transcellular Cl^? absorption in the kidney, has yet to be established. This is partly because investigation of heterologous expression has involved rat or human ClC-K models, whereas characterization of the native renal tubule has been done in mice. Here, we investigate the electrophysiological properties of mouse ClC-K1 channels heterologously expressed in Xenopus laevis oocytes and in HEK293 cells with or without their accessory Barttin subunit. Current amplitudes and plasma membrane insertion of mouse ClC-K1 were enhanced by Barttin. External basic pH or elevated calcium stimulated currents followed the anion permeability sequence Cl^? > Br^? > NO₃^? > I^?. Single-channel recordings revealed a unit conductance of ~ 40 pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~ ? 65 mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~ 20 pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~ + 25 mV. The unit conductance and voltage dependence of wild-type and V166E ClC-K1 were not affected by Barttin. Owing to their strikingly similar properties, we propose that the ClC-K1/Barttin complex is the molecular substrate of a chloride channel previously detected in the mouse thick ascending limb (Paulais et al., J Membr. Biol, 1990, 113:253-260).