Interaction Between the Angiotensin-(1–7) Mas Receptor and the Dopamine D2 Receptor

Abstract

Ang (angiotensin) 1–7 MasR (Mas receptor) and D2R (dopamine D2 receptor) stimulation is coupled to anti-inflammatory responses. In the present work, we investigated the hypothesis that the anti-inflammatory action mediated by both receptors results from MasR-D2R heteromerization. Human monocyte (THP-1) cells differentiated to macrophages and exposed to lipopolysaccharide were employed. Ang (1–7) and the D2R agonist SUM (sumanirole) induced a decrease in proinflammatory IL (interleukin) 6 release in human macrophages exposed to a proinflammatory stimulus. The Ang (1–7)–induced decrease in IL-6 was blocked by the D2R antagonist. Conversely, the SUM induced decrease in IL-6 was prevented by the MasR antagonist and when MasR expression was downregulated, suggesting MasR-D2R interaction. Co-immunoprecipitation assay in THP-1 cells and in human monocyte differentiated macrophages from peripheral blood mononuclear cells confirmed MasR-D2R interaction. To avoid the influence from other receptors, MasR-D2R interaction was characterized in transfected human embryonic kidney 293T cells. Fluorescence resonance energy transfer analysis showed that MasR and D2R formed a constitutive heteromer, which was not modified by their agonists. Ang (1–7) and dopamine stimulated ERK (extracellular signal-regulated kinase) 1/2 and Akt (protein kinase B) phosphorylation only in cells expressing MasR-D2R heteromers, but not in cells expressing each receptor alone. Ang (1–7)–stimulated ERK1/2 and Akt phosphorylation was prevented by D2R blockade while the effect of dopamine was prevented by MasR blockade, reinforcing the fact that MasR-D2R heteromers are involved in ERK1/2 and Akt activation induced by their agonists. Our findings provide new evidence regarding the mechanisms underlying the cross-talk between the Ang (1–7)/MasR axis and the dopaminergic system in response to a proinflammatory process.