Increased level of p63RhoGEF and RhoA/Rho kinase activity in hypertensive patients

OBJECTIVE:p63RhoGEF, a guanine nucleotide exchange factor, has been reported ‘in vitro’ as key mediator of the angiotensin II-induced RhoA/Rho kinase activation leading to vasoconstriction and cardiovascular remodeling. We assessed p63RhoGEF gene and protein expression and RhoA/Rho kinase activity in essential hypertensive and Bartterʼs and Gitelmanʼs syndrome patients, a human model opposite to hypertension; the latter have, in fact, increased plasma angiotensin II, activation of the renin–angiotensin system, yet normotension/hypotension, reduced peripheral resistance and lack of cardiovascular remodeling due to an endogenously blunted angiotensin II type 1 receptor signaling. METHODS:Mononuclear cell p63RhoGEF gene and protein expression and the phosphorylation status of the myosin phosphatase target protein-1 (MYPT-1), marker of Rho kinase activity, were assessed in essential hypertensive patients, Bartterʼs/Gitelmanʼs patients and healthy individuals by quantitative real-time PCR and western blot. RESULTS:p63RhoGEF mRNA and protein level and MYPT-1 phosphorylation status were higher in hypertensive patients and lower in Bartterʼs/Gitelmanʼs patients compared with healthy individualsp63RhoGEF mRNA level0.59 ± 0.17 ΔΔCt vs. 0.37 ± 0.17 vs. 0.20 ± 0.19, analysis of variance (ANOVA)P