Preferential assembly of epithelial sodium channel (ENaC) subunits in Xenopus oocytes: role of furin-mediated endogenous proteolysis.

Détails

ID Serval
serval:BIB_0734FF995F39
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Preferential assembly of epithelial sodium channel (ENaC) subunits in Xenopus oocytes: role of furin-mediated endogenous proteolysis.
Périodique
Journal of Biological Chemistry
Auteur(s)
Harris M., Garcia-Caballero A., Stutts M.J., Firsov D., Rossier B.C.
ISSN
0021-9258
Statut éditorial
Publié
Date de publication
2008
Peer-reviewed
Oui
Volume
283
Numéro
12
Pages
7455-7463
Langue
anglais
Notes
Publication types: Journal Article
Résumé
The epithelial sodium channel (ENaC) is preferentially assembled into heteromeric alphabetagamma complexes. The alpha and gamma (not beta) subunits undergo proteolytic cleavage by endogenous furin-like activity correlating with increased ENaC function. We identified full-length subunits and their fragments at the cell surface, as well as in the intracellular pool, for all homo- and heteromeric combinations (alpha, beta, gamma, alphabeta, alphagamma, betagamma, and alphabetagamma). We assayed corresponding channel function as amiloride-sensitive sodium transport (I(Na)). We varied furin-mediated proteolysis by mutating the P1 site in alpha and/or gamma subunit furin consensus cleavage sites (alpha(mut) and gamma(mut)). Our findings were as follows. (i) The beta subunit alone is not transported to the cell surface nor cleaved upon assembly with the alpha and/or gamma subunits. (ii) The alpha subunit alone (or in combination with beta and/or gamma) is efficiently transported to the cell surface; a surface-expressed 65-kDa alpha ENaC fragment is undetected in alpha(mut)betagamma, and I(Na) is decreased by 60%. (iii) The gamma subunit alone does not appear at the cell surface; gamma co-expressed with alpha reaches the surface but is not detectably cleaved; and gamma in alphabetagamma complexes appears mainly as a 76-kDa species in the surface pool. Although basal I(Na) of alphabetagamma(mut) was similar to alphabetagamma, gamma(mut) was not detectably cleaved at the cell surface. Thus, furin-mediated cleavage is not essential for participation of alpha and gamma in alphabetagamma heteromers. Basal I(Na) is reduced by preventing furin-mediated cleavage of the alpha, but not gamma, subunits. Residual current in the absence of furin-mediated proteolysis may be due to non-furin endogenous proteases.
Mots-clé
Amiloride/pharmacology, Animals, Cell Membrane/genetics, Cell Membrane/metabolism, Epithelial Sodium Channel/genetics, Epithelial Sodium Channel/metabolism, Female, Furin/genetics, Furin/metabolism, Ion Transport/drug effects, Oocytes/cytology, Oocytes/metabolism, Protein Processing, Post-Translational/physiology, Protein Structure, Quaternary/physiology, Protein Subunits/genetics, Protein Subunits/metabolism, Rats, Sodium/metabolism, Sodium Channel Blockers/pharmacology, Xenopus laevis
Pubmed
Web of science
Création de la notice
29/01/2009 23:14
Dernière modification de la notice
03/03/2018 13:27
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