G protein‐coupled receptor (GPCR) arrays identify physiologically relevant targets in Pulmonary Artery Smooth Muscle Cells (PASMC): mRNA to Function

Abstract

Pulmonary arterial hypertension (PAH) is characterized by increased pulmonary vascular resistance, in part due to increased pulmonary artery smooth muscle cells (PASMC). Since cyclic AMP (cAMP) decreases proliferation of PASMC, G protein‐coupled receptors (GPCRs) that couple Gαs are potential targets for PAH. Using a TaqMan®GPCR array and human PASMC we identified that PASMC express >130 GPCRs, at least 50 of which regulate cAMP levels. Using real‐time PCR and GPCR agonists, we investigated the relationship between GPCR expression and function by testing if the highest, intermediate and lowest expressed Gαs‐coupled GPCRs (determined by cycle threshold [ΔCt]) in PASMC generate relative amounts of cAMP (by radioimmunoassay). The highest, intermediate and lowest Gαs‐coupled GPCR that we tested were the adenosine 2B receptor (A2BR, ΔCt = 18), the prostaglandin E receptor 2 receptor (PGE2R, ΔCT = 22) and the gastric inhibitory polypeptide receptor (GIPR, ΔCt = 24). cAMP accumulation (fmol) in response to receptor agonists, CV1808 (A2BR, 1μM, 1.8 fmol), Butaprost (PGE2R, 1μM, 1.2 fmol) and GIP (GIPR,1μM, 0.7 fmol) correlated with receptor mRNA expression (r2=0.90). Moreover, cAMP dose‐dependently decreased PASMC proliferation. Our data show that the mRNA expression of Gαs‐coupled GPCRs predicts function, implying such an approach can identify GPCRs in PASMC that may be therapeutic targets for PAH. NIH funded.