Progesterone down-regulates the open probability of the amiloride-sensitive epithelial sodium channel via a Nedd4-2-dependent mechanism.


Autoria(s): Michlig S.; Harris M.; Loffing J.; Rossier B.C.; Firsov D.
Data(s)

2005

Resumo

Activation of the mitogen-activated protein (MAP) kinase cascade by progesterone in Xenopus oocytes leads to a marked down-regulation of activity of the amiloride-sensitive epithelial sodium channel (ENaC). Here we have studied the signaling pathways involved in progesterone effect on ENaC activity. We demonstrate that: (i) the truncation of the C termini of the alphabetagammaENaC subunits results in the loss of the progesterone effect on ENaC; (ii) the effect of progesterone was also suppressed by mutating conserved tyrosine residues in the Pro-X-X-Tyr (PY) motif of the C termini of the beta and gamma ENaC subunits (beta(Y618A) and gamma(Y628A)); (iii) the down-regulation of ENaC activity by progesterone was also suppressed by co-expression ENaC subunits with a catalytically inactive mutant of Nedd4-2, a ubiquitin ligase that has been previously demonstrated to decrease ENaC cell-surface expression via a ubiquitin-dependent internalization/degradation mechanism; (iv) the effect of progesterone was significantly reduced by suppression of consensus sites (beta(T613A) and gamma(T623A)) for ENaC phosphorylation by the extracellular-regulated kinase (ERK), a MAP kinase previously shown to facilitate the binding of Nedd4 ubiquitin ligases to ENaC; (v) the quantification of cell-surface-expressed ENaC subunits revealed that progesterone decreases ENaC open probability (whole cell P(o), wcP(o)) and not its cell-surface expression. Collectively, these results demonstrate that the binding of active Nedd4-2 to ENaC is a crucial step in the mechanism of ENaC inhibition by progesterone. Upon activation of ERK, the effect of Nedd4-2 on ENaC open probability can become more important than its effect on ENaC cell-surface expression.

Identificador

http://serval.unil.ch/?id=serval:BIB_181DFACEE605

isbn:0021-9258 (Print)

pmid:16172119

doi:10.1074/jbc.M506308200

isiid:000233239800021

Idioma(s)

en

Fonte

Journal of Biological Chemistry, vol. 280, no. 46, pp. 38264-38270

Palavras-Chave #Aldosterone/pharmacology; Amiloride/pharmacology; Amino Acid Motifs; Animals; Binding Sites; Biotinylation; Catalysis; Cell Membrane/metabolism; Down-Regulation; Endosomal Sorting Complexes Required for Transport; Epithelial Sodium Channel; Extracellular Signal-Regulated MAP Kinases/metabolism; Humans; MAP Kinase Signaling System; Mutation; Oocytes/metabolism; Oxygen/metabolism; Patch-Clamp Techniques; Phosphorylation; Progesterone/chemistry; Progesterone/metabolism; Protein Binding; Protein Structure, Tertiary; RNA, Complementary/metabolism; Rats; Signal Transduction; Sodium Channels/metabolism; Sodium-Phosphate Cotransporter Proteins, Type IIa/physiology; Time Factors; Tyrosine/chemistry; Ubiquitin/chemistry; Ubiquitin-Protein Ligases/physiology; Xenopus
Tipo

info:eu-repo/semantics/article

article