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 (R) associated with cardiac, renal and cerebral protective responses. Physiological evidence suggests that Mas R undergoes agonist-dependent desensitization, but the underlying molecular mechanism regulating R activity is unknown. We investigated the hypothesis that Mas R desensitizes and internalizes upon stimulation with Ang-(1-7). For this purpose, we generated a chimera between the Mas R and the 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 min. Following the time course of [125I]Ang-(1-7) endocytosis we observed that half of MasR-YFP underwent endocytosis after 10 min and this was blocked by a Mas R 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, Mas R undergoes endocytosis upon stimulation with Ang-(1-7) and this event may explain the desensitization of Mas R responsiveness. In this way, Mas R activity and density may be tightly controlled by the cell.

MAS1 Receptor Trafficking Involves ERK1/2 Activation Through a β-Arrestin2–Dependent Pathway

“…We have previously shown that Ang-(1-7) elicited the same affinity for both the chimera MAS1R-YFP and MAS1R. 17 …”

“…The plasmid containing MAS1R-YFP cDNA was obtained as previously described. 17 shRNA ß-arrestin2 was from SantaCruz. All other chemicals were analytical grade reagents of the highest purity available.…”

“…9,15,16 For instance, β-arrestins scaffold various components of the extracellular signal-regulated kinase (ERK) cascade, bringing them into proximity to promote ERK activation. 17 Signaling that is mediated by β-arrestins has distinct biochemical and functional consequences from those mediated by G proteins, and several biased ligands and receptors have been identified that preferentially signal through either G protein- or β-arrestin-mediated pathways. 16 …”

“…17 However, no knowledge about MAS1R trafficking has been reported. We hypothesize that MAS1R interacts with β-arrestins upon agonist stimulation and is then internalized into early endosomes through clathrin and caveolar pathways in a dynamin-dependent manner.…”

MAS promoter regulation: a role for Sry and tyrosine nitration of the KRAB domain of ZNF274 as a feedback mechanism

“…Binding and activation of the MAS receptor by Ang-(1-7) results in stimulation of nitric oxide production, and in internalization and degradation of MAS [29]. Some tissues such as cardiac myocytes have been shown to desensitize to Ang-(1-7) signaling, likely through this degradation of MAS upon activation.…”