Intracellular ubiquitylation of the epithelial Na+ channel controls extracellular proteolytic channel activation via conformational change.

Détails

ID Serval
serval:BIB_A490D71A413D
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Intracellular ubiquitylation of the epithelial Na+ channel controls extracellular proteolytic channel activation via conformational change.
Périodique
Journal of Biological Chemistry
Auteur(s)
Ruffieux-Daidié D., Staub O.
ISSN
1083-351X (Electronic)
ISSN-L
0021-9258
Statut éditorial
Publié
Date de publication
2011
Volume
286
Numéro
4
Pages
2416-2424
Langue
anglais
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Résumé
The epithelial Na(+) channel ENaC is a key player in the maintenance of whole body Na(+) balance, and consequently of blood pressure. It is tightly regulated by numerous signaling pathways including ubiquitylation via the ubiquitin-protein ligase Nedd4-2. This mechanism is itself under the control of several kinases, which phosphorylate Nedd4-2, thereby interfering with ENaC/Nedd4-2 interaction, or by Usp2-45, which binds to and deubiquitylates ENaC. Another, different regulatory mechanism concerns the proteolytic activation of ENaC, during which the channel is cleaved on its luminal side by intracellular convertases such as furin, and further activated by extracellular proteases such as CAP-1. This process is regulated as well but the underlying mechanisms are not understood. Previously, evidence was provided that the ubiquitylation status of ENaC may affect the cleavage of the channel. When ubiquitylation of ENaC was reduced, either by co-expressing Usp2-45, or mutating either the ENaC PY-motifs (i.e. the binding sites for Nedd4-2) or intracellular lysines (i.e. ubiquitylation sites), the level of channel cleavage was increased. Here we demonstrate that lysine-mutated ENaC channels are not ubiquitylated at the cell surface, are preferentially cleaved, and Usp2-45 does not affect their cleavage efficiency. We further show by limited proteolysis that the intracellular ubiquitylation status of ENaC affects the extracellular conformation of αENaC, by demonstrating that non-ubiquitylated channels are more efficiently cleaved when treated with extracellularly added trypsin or chymotrypsin. These results present a new paradigm in which an intracellular, post-translational modification (e.g. ubiquitylation) of a transmembrane protein can affect its extracellular conformation.
Mots-clé
Amino Acid Motifs, Chymotrypsin/pharmacology, Endopeptidases/genetics, Endopeptidases/metabolism, Endosomal Sorting Complexes Required for Transport/genetics, Endosomal Sorting Complexes Required for Transport/metabolism, Epithelial Sodium Channel/genetics, Epithelial Sodium Channel/metabolism, Furin/genetics, Furin/metabolism, HEK293 Cells, Humans, Mutation, Signal Transduction/drug effects, Signal Transduction/physiology, Trypsin/pharmacology, Ubiquitin-Protein Ligases/genetics, Ubiquitin-Protein Ligases/metabolism, Ubiquitination/drug effects, Ubiquitination/physiology
Pubmed
Web of science
Open Access
Oui
Création de la notice
20/03/2011 18:24
Dernière modification de la notice
08/05/2019 23:09
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