miRNA-200c-3p promotes endothelial to mesenchymal transition and neointimal hyperplasia in artery bypass grafts.

Increasing evidence has suggested a critical role for endothelial-to-mesenchymal transition (EndoMT) in a variety of pathological conditions. MicroRNA-200c-3p (miR-200c-3p) has been implicated in epithelial-to-mesenchymal transition. However, the functional role of miR-200c-3p in EndoMT and neointimal hyperplasia in artery bypass grafts remains largely unknown. Here we demonstrated a critical role for miR-200c-3p in EndoMT. Proteomics and luciferase activity assays revealed that fermitin family member 2 (FERM2) is the functional target of miR-200c-3p during EndoMT. FERMT2 gene inactivation recapitulates the effect of miR-200c-3p overexpression on EndoMT, and the inhibitory effect of miR-200c-3p inhibition on EndoMT was reversed by FERMT2 knockdown. Further mechanistic studies revealed that FERM2 suppresses smooth muscle gene expression by preventing serum response factor nuclear translocation and preventing endothelial mRNA decay by interacting with Y-box binding protein 1. In a model of aortic grafting using endothelial lineage tracing, we observed that miR-200c-3p expression was dramatically up-regulated, and that EndoMT contributed to neointimal hyperplasia in grafted arteries. MiR-200c-3p inhibition in grafted arteries significantly up-regulated FERM2 gene expression, thereby preventing EndoMT and reducing neointimal formation. Importantly, we found a high level of EndoMT in human femoral arteries with atherosclerotic lesions, and that miR-200c-3p expression was significantly increased, while FERMT2 expression levels were dramatically decreased in diseased human arteries. Collectively, we have documented an unexpected role for miR-200c-3p in EndoMT and neointimal hyperplasia in grafted arteries. Our findings offer a novel therapeutic opportunity for treating vascular diseases by specifically targeting the miR-200c-3p/FERM2 regulatory axis.