title: Characterization of the mouse ClC-K1/Barttin chloride channel.
abstract: 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 ~40pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~-65mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~20pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~+25mV. 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).
authors.affiliation: UPMC Univ Paris 06, UMRS 872, Laboratoire de génomique, physiologie et physiopathologie rénales, F-75005 Paris, France; INSERM, UMRS 872, Laboratoire de génomique, physiologie et physiopathologie rénales, F-75005 Paris, France; CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, F-75005, Paris, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: L'Hoste
authors.forename: Alexei
authors.initials: A
authors.lastname: Diakov
authors.forename: Olga
authors.initials: O
authors.lastname: Andrini
authors.forename: Mathieu
authors.initials: M
authors.lastname: Genete
authors.forename: Laurent
authors.initials: L
authors.lastname: Pinelli
authors.forename: Teddy
authors.initials: T
authors.lastname: Grand
authors.forename: Mathilde
authors.initials: M
authors.lastname: Keck
authors.forename: Marc
authors.initials: M
authors.lastname: Paulais
authors.forename: Laurent
authors.initials: L
authors.lastname: Beck
authors.forename: Christoph
authors.initials: C
authors.lastname: Korbmacher
authors.forename: Jacques
authors.initials: J
authors.lastname: Teulon
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lourdel
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007684:Kidney Tubules / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011994:Recombinant Proteins / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D018118:Chloride Channels; C489933:Clcnka protein, mouse; D011994:Recombinant Proteins
keywords: 2-(phenylamino) benzoic acid; 4,4′-diisothiocyanato-2,2′-stilbene disulfonic acid disodium salt; 5-nitro-2-(3-phenylpropylamino) benzoic acid; CCD; CNT; CTAL; Chloride channel; ClC; ClC-K; ClC-K1; DCT; DIDS; DPC; Kidney; NPPB; OMCD; Patch-clamp; connecting tubule; cortical collecting duct; cortical thick ascending limb; distal convoluted tubule; kidney chloride channel; outer medullary collecting duct