G-Protein–Coupled Receptor MrgD Is a Receptor for Angiotensin-(1–7) Involving Adenylyl Cyclase, cAMP, and Phosphokinase A

• Published in: Hypertension (Dallas, Tex. 1979) Tex. 1979), 2016-07, Vol.68 (1), p.185-194
• Main Authors: Tetzner, Anja, Gebolys, Kinga, Meinert, Christian, Klein, Sabine, Uhlich, Anja, Trebicka, Jonel, Villacañas, Óscar, Walther, Thomas
• Format: Article
• Language: English
• Subjects: Adenylyl Cyclases - drug effects; Adenylyl Cyclases - metabolism; Angiotensin I - pharmacology; Animals; Blotting, Western; Cells, Cultured; Cyclic AMP-Dependent Protein Kinases - metabolism; Disease Models, Animal; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Female; HEK293 Cells - drug effects; HEK293 Cells - metabolism; Humans; Hypertension - drug therapy; Hypertension - enzymology; Male; Mesangial Cells - drug effects; Mesangial Cells - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Peptide Fragments - pharmacology; Phosphotransferases - metabolism; Receptors, G-Protein-Coupled - metabolism; Renin-Angiotensin System - drug effects; Sensitivity and Specificity
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/HYPERTENSIONAHA.116.07572

Angiotensin (Ang)-(1–7) has cardiovascular protective effects and is the opponent of the often detrimental Ang II within the renin–angiotensin system. Although it is well accepted that the G-protein–coupled receptor Mas is a receptor for the heptapeptide, the lack in knowing initial signaling molecules stimulated by Ang-(1–7) prevented definitive characterization of ligand/receptor pharmacology as well as identification of further hypothesized receptors for the heptapeptide. The study aimed to identify a second messenger stimulated by Ang-(1–7) allowing confirmation as well as discovery of the heptapeptide’s receptors. Ang-(1–7) elevates cAMP concentration in primary cells, such as endothelial or mesangial cells. Using cAMP as readout in receptor-transfected human embryonic kidney (HEK293) cells, we provided pharmacological proof that Mas is a functional receptor for Ang-(1–7). Moreover, we identified the G-protein–coupled receptor MrgD as a second receptor for Ang-(1–7). Consequently, the heptapeptide failed to increase cAMP concentration in primary mesangial cells with genetic deficiency in both Mas and MrgD. Mice deficient in MrgD showed an impaired hemodynamic response after Ang-(1–7) administration. Furthermore, we excluded the Ang II type 2 receptor as a receptor for the heptapeptide but discovered that the Ang II type 2 blocker PD123319 can also block Mas and MrgD receptors. Our results lead to an expansion and partial revision of the renin–angiotensin system, by identifying a second receptor for Ang-(1–7), by excluding Ang II type 2 as a receptor for the heptapeptide, and by enforcing the revisit of such publications which concluded Ang II type 2 function by only using PD123319.