Protease modulation of the activity of the epithelial sodium channel expressed in Xenopus oocytes.

Détails

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Etat: Public
Version: de l'auteur⸱e
ID Serval
serval:BIB_DF7F00FCEDFD
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Protease modulation of the activity of the epithelial sodium channel expressed in Xenopus oocytes.
Périodique
Journal of General Physiology
Auteur⸱e⸱s
Chraïbi A., Vallet V., Firsov D., Hess S.K., Horisberger J.D.
ISSN
0022-1295 (Print)
ISSN-L
0022-1295
Statut éditorial
Publié
Date de publication
1998
Volume
111
Numéro
1
Pages
127-138
Langue
anglais
Résumé
We have investigated the effect of extracellular proteases on the amiloride-sensitive Na+ current (INa) in Xenopus oocytes expressing the three subunits alpha, beta, and gamma of the rat or Xenopus epithelial Na+ channel (ENaC). Low concentrations of trypsin (2 microg/ml) induced a large increase of INa within a few minutes, an effect that was fully prevented by soybean trypsin inhibitor, but not by amiloride. A similar effect was observed with chymotrypsin, but not with kallikrein. The trypsin-induced increase of INa was observed with Xenopus and rat ENaC, and was very large (approximately 20-fold) with the channel obtained by coexpression of the alpha subunit of Xenopus ENaC with the beta and gamma subunits of rat ENaC. The effect of trypsin was selective for ENaC, as shown by the absence of effect on the current due to expression of the K+ channel ROMK2. The effect of trypsin was not prevented by intracellular injection of EGTA nor by pretreatment with GTP-gammaS, suggesting that this effect was not mediated by G proteins. Measurement of the channel protein expression at the oocyte surface by antibody binding to a FLAG epitope showed that the effect of trypsin was not accompanied by an increase in the channel protein density, indicating that proteolysis modified the activity of the channel present at the oocyte surface rather than the cell surface expression. At the single channel level, in the cell-attached mode, more active channels were observed in the patch when trypsin was present in the pipette, while no change in channel activity could be detected when trypsin was added to the bath solution around the patch pipette. We conclude that extracellular proteases are able to increase the open probability of the epithelial sodium channel by an effect that does not occur through activation of a G protein-coupled receptor, but rather through proteolysis of a protein that is either a constitutive part of the channel itself or closely associated with it.
Mots-clé
Amiloride/pharmacology, Animals, Calcium/physiology, Chymotrypsin/pharmacology, Diuretics/pharmacology, Epinephrine/pharmacology, Epithelial Cells/chemistry, GTP-Binding Proteins/metabolism, Gene Expression, Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology, Oocytes/chemistry, Oocytes/drug effects, Patch-Clamp Techniques, Rats, Second Messenger Systems/drug effects, Second Messenger Systems/physiology, Sodium Channels/genetics, Sodium Channels/metabolism, Sympathomimetics/pharmacology, Trypsin/pharmacology, Xenopus
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 12:32
Dernière modification de la notice
20/08/2019 16:03
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