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

Goichi Ogimoto, Guillermo A. Yudowski, Christopher J. Barker, Martin Köhler, Adrian I. Katz, Eric Féraille, Carlos H. Pedemonte, Per Olof Berggren, Alejandro M. Bertorello

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

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 α-subunit followed by endocytosis of active molecules. We examined whether agonists that counteract this effect do so by dephosphorylation of the α-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 α-subunit phosphorylation, but by impaired endocytosis of α-subunits into clathrin vesicles and early and late endosomes. Dopamine-induced inhibition of NKA activity and α-subunit endocytosis required the interaction of adaptor protein 2 (AP-2) with the catalytic α-subunit. Phosphorylation of the α-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 (InsP6), whereas oxymetazoline prevented this effect. Similar increments (above basal) in the concentration of InsP6 induced by oxymetazoline prevented AP-2 binding to the NKA α-subunit in response to dopamine. In conclusion, inhibition of NKA activity can be reversed by preventing its endocytosis without altering the state of α-subunit phosphorylation; increased InsP6 in response to G protein-coupled receptor signals blocks the recruitment of AP-2 and thereby clathrin-dependent endocytosis of NKA.

Original languageEnglish (US)
Pages (from-to)3242-3247
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume97
Issue number7
DOIs
StatePublished - Mar 28 2000

ASJC Scopus subject areas

  • General

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