ACE2 Activation by Tripeptide IRW (Ile-Arg-Trp) Depends on the G Protein-Coupled Receptor 30 Signaling Cascade

Abstract

This study aimed to understand how specific cell-bound receptors influence ACE2 activation by IRW. Our results showed that G protein-coupled receptor 30 (GPR30), a 7-transmembrane domain protein, was involved in IRW-mediated ACE2 increase. IRW treatment (50 μM) significantly increased the GPR30 pool levels (3.2 ± 0.5 folds) (p < 0.001). IRW treatment also boosted the consecutive GEF (guanine nucleotide exchange factor) activity (2.2 ± 0.2 folds) (p < 0.001), and GNB1 levels (2.0 ± 0.5 folds) (p < 0.05), associated with the functional subunits of G proteins, in cells. These results were translated in hypertensive animal studies as well (p < 0.05), indicated by an increase in the aortal levels of GPR30 (p < 0.01); further experiments showed an increase in downstream PIP3/PI3K/Akt pathway activation following IRW treatment. The blockade of GPR30 by an antagonist and siRNA in cells abolished the ACE2-activating ability of IRW, as shown by the depleted levels of ACE2 mRNA (p < 0.001), protein levels in whole cells and membrane, angiotensin (1-7) (p < 0.01), and ACE2 promoter HNF1α (p < 0.05). Finally, the GPR30 blockade in ACE2-overexpressing cells using the antagonist (p < 0.01) and siRNA (p < 0.05) significantly depleted the innate cellular pool of ACE2, thus confirming the relationship between the membrane-bound GPR30 and ACE2. Overall, these results showed that the vasodilatory peptide IRW could activate ACE2 via the membrane-bound receptor GPR30.