Reduced expression of regulator of G-protein signaling 2 (RGS2) in hypertensive patients increases calcium mobilization and ERK1/2 phosphorylation induced by angiotensin II

Context RGS2 (regulators of G-protein signaling) is a negative regulator of Gq protein signaling, which mediates the action of several vasoconstrictors. RGS2-deficient mouse line exhibits a hypertensive phenotype and a prolonged response to vasoconstrictors. Objective To compare RGS2 expression in peripheral blood mononuclear cells (PBM) and cultured fibroblasts from normotensive subjects and hypertensive patients. Methods PBM were isolated from 100 controls and 150 essential hypertensives. Additionally, fibroblasts were isolated from skin biopsy of 11 normotensives and 12 hypertensives and cultured up to the 3rd passage. Quantitative mRNA and protein RGS2 expression was performed by real-time quantitative reverse transcriptase-polymerase chain reaction and by immunoblotting, respectively. Free Ca2+ measurement was performed in monolayers of 24-hour serum-deprived cells, using FURA-2 AM. ERK1/2 phosphorylation was measured by immunoblotting. Polymorphism (C1114G) in 3’UTR region of the RGS2 gene was investigated by direct sequencing and real-time PCR. Results RGS2 mRNA expression was significantly lower in PBM and in fibroblasts from hypertensives, in comparison to normotensives. C1114G polymorphism was associated with RGS2 expression, with the lowest values in GG hypertensives. The 1114G allele frequency was increased in hypertensives compared with normotensives. Angiotensin II-stimulated intracellular Ca2+ increase and ERK 1/2 phosphorylation were higher in fibroblasts from hypertensive patients compared with control subjects, and in those with the G allele, independently of the blood pressure status. The Angiotensin II-stimulated Ca2+ mobilization and ERK1/2 phosphorylation were negatively correlated with RGS2 mRNA expression. Conclusion Low expression of RGS2 contributes to increased G protein-coupled signaling in hypertensive patients. C1114G polymorphism may be associated to low RGS2 expression and blood pressure increase in man.