Abstract P162: In vivo miR-431 Inhibition Protects Against Vascular Damage and Hypertension

Abstract

Background: Vascular injury is an early manifestation of hypertension. microRNAs (miRNAs) play an important role in cardiovascular disease, but their implication in vascular injury remains unclear. Using small and total RNA sequencing, we identified in murine mesenteric arteries (MAs) a conserved angiotensin (Ang) II-upregulated Dlk1-Dio3 miRNA miR-431 that correlated with blood pressure (BP), and an Ang II-downregulated BP-correlated conserved putative miR-431 target, the transcriptional factor ETS homologous factor ( Ehf ). miR-431 might be involved in vascular remodeling as Ehf regulates expression of extracellular matrix genes including alpha-1 type I collagen ( Col1a1 ) and of other Dlk1-Dio3 miRNAs. In this study, we proposed to validate the miR-431- Ehf - Col1a1 interaction in vitro and in vivo , and determine whether miR-431 inhibition antagonizes angiotensin (Ang) II-induced hypertension and vascular injury. Methods and Results: Transfection of miR-431 mimics into human aortic smooth muscle cells decreased Ehf expression (0.13±0.05 fold, P <0.001) and increased Col1a1 (1.7±0.5 fold, P <0.01), whereas miR-431 inhibitors increased Ehf (1.5±0.2 fold, P <0.001) and decreased Col1a1 (0.89±0.11 fold, P <0.05). Ehf siRNA transfection increased 1.2±0.1 fold Col1a1 ( P <0.01). Co-transfection of miR-431 mimics with luciferase reporter vectors that contain the wild-type but not mutated miR-431 human EHF 3’ UTR binding site decreased 0.51±0.01 fold ( P <0.05) luciferase expression compared to scrambled mimics. miR-431 inhibitor IV injection in mice at day 0 and 7 of Ang II infusion decreased miR-431 (0.16±0.05 fold, P <0.01), Col1a1 (0.58±0.11 fold, P <0.05), increased Ehf (2.9±0.8 fold, P <0.05) in MAs, delayed BP elevation ( P <0.01), improved endothelium-dependent relaxation (33±8 vs 64±7%, P <0.05) and reduced vascular stiffness (strain at 140mmHg: 0.68±0.02 vs 0.58±0.02 ΔD/D, P <0.01) compared to scrambled mimics-injected Ang II-infused mice. Conclusion and Perspectives: miR-431 and its target Ehf may act as master regulators in the pathophysiology of vascular damage in hypertension. miR-431 inhibition has the potential to serve as a novel therapeutic approach for treatment of vascular damage and hypertension.