G protein-coupled receptors regulate Na+,K+-ATPase activity and endocytosis by modulating the recruitment of adaptor protein 2 and clathrin.

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TítuloG protein-coupled receptors regulate Na+,K+-ATPase activity and endocytosis by modulating the recruitment of adaptor protein 2 and clathrin.
Publication TypeJournal Article
Year of Publication2000
AutoresOgimoto, G, Yudowski, GA, Barker, CJ, Köhler, M, Katz, AI, Féraille, E, Pedemonte, CH, Berggren, PO, Bertorello, AM
JournalProc Natl Acad Sci U S A
Volume97
Issue7
Pagination3242-7
Date Published2000 Mar 28
ISSN0027-8424
Palabras claveAdaptor Protein Complex alpha Subunits, Adaptor Proteins, Vesicular Transport, Animals, Clathrin, Dopamine, Endocytosis, GTP-Binding Proteins, Inositol Phosphates, Membrane Proteins, Oxymetazoline, Phosphatidylinositol 3-Kinases, Phosphorylation, Protein Binding, Rats, Rats, Sprague-Dawley, Receptors, Cell Surface, Sodium-Potassium-Exchanging ATPase
Abstract

Inhibition of Na(+),K(+)-ATPase (NKA) activity in renal epithelial cells by activation of G protein-coupled receptors is mediated by phosphorylation of the catalytic alpha-subunit followed by endocytosis of active molecules. We examined whether agonists that counteract this effect do so by dephosphorylation of the alpha-subunit or by preventing its internalization through a direct interaction with the endocytic network. Oxymetazoline counteracted the action of dopamine on NKA activity, and this effect was achieved not by preventing alpha-subunit phosphorylation, but by impaired endocytosis of alpha-subunits into clathrin vesicles and early and late endosomes. Dopamine-induced inhibition of NKA activity and alpha-subunit endocytosis required the interaction of adaptor protein 2 (AP-2) with the catalytic alpha-subunit. Phosphorylation of the alpha-subunit is essential because dopamine failed to promote such interaction in cells lacking the protein kinase C phosphorylation residue (S18A). Confocal microscopy confirmed that oxymetazoline prevents incorporation of NKA molecules into clathrin vesicles by inhibiting the ability of dopamine to recruit clathrin to the plasma membrane. Dopamine decreased the basal levels of inositol hexakisphosphate (InsP(6)), whereas oxymetazoline prevented this effect. Similar increments (above basal) in the concentration of InsP(6) induced by oxymetazoline prevented AP-2 binding to the NKA alpha-subunit in response to dopamine. In conclusion, inhibition of NKA activity can be reversed by preventing its endocytosis without altering the state of alpha-subunit phosphorylation; increased InsP(6) in response to G protein-coupled receptor signals blocks the recruitment of AP-2 and thereby clathrin-dependent endocytosis of NKA.

DOI10.1073/pnas.060025597
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID10716725
PubMed Central IDPMC16223
Grant ListDK53460 / DK / NIDDK NIH HHS / United States