title: Heterogeneity in the processing of CLCN5 mutants related to Dent disease.
abstract: Mutations in the electrogenic Cl(-)/H(+) exchanger ClC-5 gene CLCN5 are frequently associated with Dent disease, an X-linked recessive disorder affecting the proximal tubules. Here, we investigate the consequences in Xenopus laevis oocytes and in HEK293 cells of nine previously reported, pathogenic, missense mutations of ClC-5, most of them which are located in regions forming the subunit interface. Two mutants trafficked normally to the cell surface and to early endosomes, and displayed complex glycosylation at the cell surface like wild-type ClC-5, but exhibited reduced currents. Three mutants displayed improper N-glycosylation, and were nonfunctional due to being retained and degraded at the endoplasmic reticulum. Functional characterization of four mutants allowed us to identify a novel mechanism leading to ClC-5 dysfunction in Dent disease. We report that these mutant proteins were delayed in their processing, and that the stability of their complex glycosylated form was reduced, causing lower cell surface expression. The early endosome distribution of these mutants was normal. Half of these mutants displayed reduced currents, whereas the other half showed abolished currents. Our study revealed distinct cellular mechanisms accounting for ClC-5 loss of function in Dent disease.
authors.affiliation: UPMC Univ Paris 06, UMR_S 872, Laboratoire de Génomique, Physiologie et Physiopathologie Rénales, Paris, France.
authors.forename: Teddy
authors.initials: T
authors.lastname: Grand
authors.forename: Sébastien
authors.initials: S
authors.lastname: L'Hoste
authors.forename: David
authors.initials: D
authors.lastname: Mordasini
authors.forename: Nadia
authors.initials: N
authors.lastname: Defontaine
authors.forename: Mathilde
authors.initials: M
authors.lastname: Keck
authors.forename: Thomas
authors.initials: T
authors.lastname: Pennaforte
authors.forename: Mathieu
authors.initials: M
authors.lastname: Genete
authors.forename: Kamel
authors.initials: K
authors.lastname: Laghmani
authors.forename: Jacques
authors.initials: J
authors.lastname: Teulon
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lourdel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000235:genetics* / Q000378:metabolism; D057973:Dent Disease / Q000235:genetics* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D016415:Sequence Alignment; D014982:Xenopus laevis
chemical_list: C097503:CLC-5 chloride channel; D018118:Chloride Channels