title: Identification and characterization of the zebrafish ClC-2 chloride channel orthologs.
abstract: ClC-2 is a Cl(-) channel that belongs to the CLC family of chloride channel/transport proteins. ClC-2 molecular role is not clear, and Clcn2 knockout mice develop blindness, sterility, and leukodystrophy by unknown reasons. ClC-2 is associated in the brain with the adhesion molecule GlialCAM, which is defective in a type of leukodystrophy, involving ClC-2 in the homeostasis of myelin. To get more insight into the functions of ClC-2, we have identified in this work the three ClC-2 orthologs in zebrafish. clcn2a and clcn2b resulted from the teleost-specific whole genome duplication, while clcn2c arose from a gene duplication from clcn2b. The expression patterns in adult tissues and embryos of zebrafish clcn2 paralogs support their subfunctionalization after the duplications, with clcn2a being enriched in excitable tissues and clcn2c in ionocytes. All three zebrafish clc-2 proteins interact with human GLIALCAM, that is able to target them to cell junctions, as it does with mammalian ClC-2. We could detect clc-2a and clc-2b inward rectified chloride currents with different voltage-dependence and kinetics in Xenopus oocytes, while clc-2c remained inactive. Interestingly, GlialCAM proteins did not modify clc-2b inward rectification. Then, our work extends the repertoire of ClC-2 proteins and provides new tools for structure-function and physiology studies.
authors.affiliation: Departament de Ciències Fisiològiques II, Unitat de Fisiologia, Universitat de Barcelona, Carrer Feixa Llarga s/n, L´Hospitalet de Llobregat, 08907, Barcelona, Spain.
authors.forename: Carla
authors.initials: C
authors.lastname: Pérez-Rius
authors.forename: Héctor
authors.initials: H
authors.lastname: Gaitán-Peñas
authors.forename: Raúl
authors.initials: R
authors.lastname: Estévez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Barrallo-Gimeno
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000090007:CLC-2 Chloride Channels; D018797:Cell Cycle Proteins; D018118:Chloride Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D030541:Databases, Genetic; D018507:Gene Expression Regulation, Developmental; D007700:Kinetics; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D009865:Oocytes; D010802:Phylogeny; D011485:Protein Binding; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014981:Xenopus; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000090007:CLC-2 Chloride Channels; D018797:Cell Cycle Proteins; D018118:Chloride Channels; D002712:Chlorides; C000715428:Clcn2 protein, mouse; C487620:HEPACAM protein, human; D011506:Proteins; D012333:RNA, Messenger; D029961:Zebrafish Proteins