microRNAs regulate nitric oxide release from endothelial cells by targeting NOS3.

Endothelial nitric oxide synthase (eNOS) encoded by nitric oxide synthase 3 (NOS3), can generate nitric oxide (NO) which serves as an important deterrent to the pathogenesis of thrombosis by modulating the activation, adhesion and aggregate formation of platelets. Three serum miRNAs (miR-195, miR-532 and miR-582) have been suggested as biomarkers for the diagnosis of deep vein thrombosis (DVT), however their potential roles in DVT is not clear. The effect of miRNAs inhibiting the expression of NOS3 was evaluated in vitro. miR-195, miR-532 and miR-582 mimic, inhibitor, and control miRNAs were transfected into endothelial cells. The roles of miR-195, miR-532 and miR-582 regulating the expression of eNOS were evaluated by real-time quantitative PCR, Western Blotting and luciferase reporter assays. NO release was measured by Griess method. We confirmed NOS3 as a direct target of miR-195 and miR-582, which binds to the 3'-UTR of NOS3 mRNA in endothelial cells. A significantly inverse correlation between these two miRNAs and eNOS expression was detected. NO release from endothelial cells was decreased when the expression level of miR-195 and miR-582 was up-regulated. These findings indicated that miR-195 and miR-582 regulated NO release by targeting 3'-UTR of NOS3 post-transcriptionally in endothelial cells. Therefore, miR-195 and miR-582 might play an important role in maintaining endothelial NO bioavailability and could be a novel target for treatment of thrombotic diseases.