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.血管平滑肌细胞（vascular smooth muscle cells, VSMCs）的增殖与表型重塑是动脉粥样硬化和再狭窄中的重要病理事件。本研究发现，微小RNA-132（microRNA-132, miR-132）可通过抑制富亮氨酸重复序列（在Flightless 1中相互作用）蛋白1（leucine-rich repeat (in Flightless 1) interacting protein-1, LRRFIP1）的表达，阻断血管平滑肌细胞的增殖。微小RNA微阵列（miRNA microarray）分析显示，大鼠颈动脉经导管损伤后，miR-132的表达水平显著上调，该结果经实时定量逆转录PCR（quantitative real-time RT-PCR）进一步验证。转染miR-132模拟物可显著抑制VSMCs增殖，而转染miR-132拮抗剂（antagomir）则可促进其增殖。生物信息学分析表明，LRRFIP1是miR-132的潜在靶标基因。miR-132以序列特异性方式，下调携带Lrrfip1 3'非翻译区（3’-untranslated region）的载体所驱动的荧光素酶活性。LRRFIP1可诱导VSMCs增殖。免疫组织化学分析显示，Lrrfip1在平滑肌基膜区域呈明显表达，动脉损伤7天后其表达模式被破坏；损伤14天后，LRRFIP1的mRNA水平降低。向大鼠颈动脉递送miR-132可减轻颈动脉损伤模型中的新生内膜增殖。本研究结果表明，miR-132是调控VSMC增殖的新型因子，可通过抑制LRRFIP1的表达阻遏新生内膜的形成。