miRNA expression profile in rat carotid artery balloon injury model

The proliferation and remodeling of vascular smooth muscle cells (VSMCs) is an important pathological event in atherosclerosis and restenosis. Here we report that microRNA-132 (miR-132) blocks vascular smooth muscle cells (VSMC) proliferation by inhibiting the expression of LRRFIP1 [leucine-rich repeat (in Flightless 1) interacting protein-1]. MicroRNA microarray revealed that miR-132 was upregulated in the rat carotid artery after catheter injury, which was further confirmed by quantitative real-time RT-PCR. Transfection of an miR-132 mimic significantly inhibited the proliferation of VSMCs, whereas transfection of an miR-132 antagomir increased it. Bioinformatics showed that LRRFIP1 is a target candidate of miR-132. miR-132 down-regulated luciferase activity driven by a vector containing the 3’-untranslated region of Lrrfip1 in a sequence-specific manner. LRRFIP1 induced VSMC proliferation. Immunohistochemical analysis revealed that Lrrfip1 was clearly expressed along with the basal laminar area of smooth muscle, and its expression pattern was disrupted 7 days after arterial injury LRRFIP1 mRNA was decreased 14 days after injury. Delivery of miR-132 to rat carotid artery attenuated neointimal proliferation in carotid artery injury models. Our results suggest that miR-132 is a novel regulator of VSMC proliferation that represses neointimal formation by inhibiting LRRFIP1 expression. Balloon injury was induced in the carotid arteries of male Sprague–Dawley rats weighing approximately 250 g. Total RNA were extracted from the arterial sections after 10 days. MicroRNA profile of the sample was compared with non-injured control.