211 Mirna-34a Reduces Neointima fommation through Inhibiting Smooth Muscle Cell Proliferation and Migration

Abstract

<h3>Background/objective</h3> We have recently reported that microRNA-34a (miR-34a) regulates vascular smooth muscle cell (VSMC) differentiation from stem cells <i>in vitro</i> and <i>in vivo</i>. However, little is known about the functional involvements of miR-34a in VSMC functions and vessel injury-induced neointima formation. In the current study, we aimed to establish the causal role of miR-34a and its target genes in VSMC proliferation, migration and neointima lesion formation. <h3>Methods and results</h3> miR-34a was significantly down-regulated in VSMCs upon various pathological stimuli, and in injured arteries. miR-34a over-expression in serum-starved VSMCs significantly inhibited VSMC proliferation and migration, while knockdown of miR-34a dramatically promoted VSMC proliferation and migration, respectively. Notch homolog 1 (Notch1), a well-reported regulator in VSMC functions and arterial remodelling, was predicted as one of the top targets of miR-34a by using several computational miRNA target prediction tools, and was negatively regulated by miR-34a in VSMCs. Luciferase assay showed miR-34a substantially repressed wild type Notch1-3’-UTR-luciferase activity in VSMCs, but not mutant Notch1-3’-UTR-luciferease reporter, confirming the Notch1 is the functional target of miR-34a in VSMCs. Data from co-transfection experiments also revealed that miR-34a inhibited VSMC proliferation and migration through modulating Notch gene expression levels. Importantly, miR-34a perivascular overexpression significantly reduced Notch1 expression levels, decreased VSMC proliferation, and inhibited neointima formation in wire-injured femoral arteries. <h3>Conclusions/implications</h3> Our data have demonstrated that miR-34a is an important regulator in VSMC functions and neointima hyperplasia, suggesting its potential therapeutic application for vascular diseases.