title: Angiotensin (1-7) induces MAS receptor internalization.
abstract: Angiotensin (Ang) (1-7) is the endogenous ligand for the G protein-coupled receptor Mas, a receptor associated with 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 is unknown. We investigated the hypothesis that MasR desensitizes and internalizes on stimulation with Ang-(1-7). For this 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 of MasR-YFP was observed by confocal microscopy. In resting cells, MasR-YFP was mostly localized to the cell membrane. Ang-(1-7) induced a redistribution of MasR-YFP to intracellular vesicles of various sizes after 5 minutes. Following the time course of [(125)I]Ang-(1-7) endocytosis, we observed that half of MasR-YFP underwent endocytosis after 10 minutes, and this was blocked by a MasR antagonist. MasR-YFP colocalized with Rab5, the early endosome antigen 1, and the adaptor protein complex 2, indicating that the R is internalized through a clathrin-mediated pathway and targeted to early endosomes after Ang-(1-7) stimulation. A fraction of MasR-YFP also colocalized with caveolin 1, suggesting that at some point MasR-YFP traverses caveolin 1-positive compartments. In conclusion, MasR undergoes endocytosis on stimulation with Ang-(1-7), and this event may explain the desensitization of MasR responsiveness. In this way, MasR activity and density may be tightly controlled by the cell.
authors.affiliation: Instituto de Química y Fisicoquímica Biológicas, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina. mariela@qb.ffyb.uba.ar
authors.forename: Mariela M
authors.initials: MM
authors.lastname: Gironacci
authors.forename: Hugo P
authors.initials: HP
authors.lastname: Adamo
authors.forename: Gerardo
authors.initials: G
authors.lastname: Corradi
authors.forename: Robson A
authors.initials: RA
authors.lastname: Santos
authors.forename: Pablo
authors.initials: P
authors.lastname: Ortiz
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Carretero
mesh_terms: D000803:Angiotensin I / Q000378:metabolism / Q000494:pharmacology*; D002478:Cells, Cultured; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D002966:Clathrin; C000715470:MAS1 protein, human; D010446:Peptide Fragments; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D000803:Angiotensin I; C118790:angiotensin I (1-7)