Angiotensin (1-7) Induces Mas Receptor Internalization

MARIELA M. GIRONACCI; ADAMO H.P.; CORRADI, G.R; ROBSON A. SANTOS; OSCAR A. CARRETERO

HYPERTENSION

LIPPINCOTT WILLIAMS & WILKINS

Año: 2011 vol. 58 p. 176 - 181

0194-911X

Angiotensin (Ang) (1-7) is the endogenous ligand for the G protein– coupled receptor Mas, a receptor associatedwith cardiac, renal, and cerebral protective responses. Physiological evidence suggests that Mas receptor (MasR)undergoes agonist-dependent desensitization, but the underlying molecular mechanism regulating receptor activity isunknown. We investigated the hypothesis that MasR desensitizes and internalizes on stimulation with Ang-(1-7). Forthis purpose, we generated a chimera between the MasR and the yellow fluorescent protein (YFP; MasR-YFP).MasR-YFP–transfected HEK 293T cells were incubated with Ang-(1-7), and the relative cellular distribution ofMasR-YFP was observed by confocal microscopy. In resting cells, MasR-YFP was mostly localized to the cellmembrane. Ang-(1-7) induced a redistribution of MasR-YFP to intracellular vesicles of various sizes after 5 minutes.Following the time course of [125I]Ang-(1-7) endocytosis, we observed that half of MasR-YFP underwent endocytosisafter 10 minutes, and this was blocked by a MasR antagonist. MasR-YFP colocalized with Rab5, the early endosomeantigen 1, and the adaptor protein complex 2, indicating that the R is internalized through a clathrin-mediated pathwayand targeted to early endosomes after Ang-(1-7) stimulation. A fraction of MasR-YFP also colocalized with caveolin1, suggesting that at some point MasR-YFP traverses caveolin 1–positive compartments. In conclusion, MasR undergoesendocytosis on stimulation with Ang-(1-7), and this event may explain the desensitization of MasR responsiveness. Inthis way, MasR activity and density may be tightly controlled by the cell.