miRNA-92a对Rho激酶调控的动脉粥样硬化血管重构的影响及机制

Rho-kinase has been identified as the effectors of the small GTP-binding protein Rho, plays an important role in various cellular functions. Literatures and our previous studies showed that Rho-kinase is closely associated with vascular remodeling in the process of atherosclerosis (AS). However, whether miRNA is involved in AS vascular remodeling by Rho kinase regulation and its mechanism has not been reported. Our group recent studies found that overexpression of miR-92a accelerated the proliferation and migration of Rho-kinase-deficient (Rho-/-) vascular smooth muscle cell (VSMC). Therefore, we hypothesized that miR-92a may be involved in vascular remodeling by Rho kinase regulation, and promote the formation of AS. On this basis, the project intends to use mice VSMC (Rho-/-) and Rho-/- mice model, observe the migration, proliferation and apoptosis of cells, and the formation of AS in mice through gain- and loss-miR92a. And further evaluate the molecular mechanism of miR-92a involving in Rho kinase regulated AS vascular remodeling by TLR, MAPK, NF-kB three signal transduction pathways. The project seeks to elucidate the mechanism of Rho-kinase regulating AS development from miRNA levels, provide new ideas for looking for drug target of AS prevention and treatment.

Rho激酶作为小G蛋白Rho效应物，在多种细胞功能中起重要作用。文献报道及我们前期研究显示Rho激酶与动脉粥样硬化(AS)进程中的血管重构密切相关。然而miRNA是否参与Rho激酶调控的血管重构及相关机制，尚未见报道。本课题组近期研究发现，过表达miR-92a可以促进Rho激酶缺失(Rho-/-)的血管平滑肌细胞(VSMC)的增殖和迁移。因此我们推测miR-92a可能参与Rho激酶调控的血管重构，从而促进AS形成。本项目在此基础上，拟利用小鼠VSMC(Rho-/-)和Rho-/-小鼠模型，通过上调和下调miR-92a，分别观察其对细胞增殖、迁移及凋亡的影响和对小鼠AS形成的影响；进一步探讨TLR、MAPK、NF-kB三条信号转导通路在miR-92a参与的Rho激酶调控的AS血管重构中的分子机制。本项目试图从miRNA水平阐明Rho激酶调控AS发生发展的机制，为寻找防治AS药物提供新的思路。

背景：虽然ROCK和miR-92a分别是动脉粥样硬化的重要调节因子，但它们在动脉粥样硬化形成中的关系仍然是一个热门研究课题。我们研究了miR-92a在ROCK信号通路中对PDGF-BB调控的VSMCs增殖和迁移的作用。.研究内容和结果：我们选用ROCK的特异性抑制剂Y27632处理VSMCs，发现miR-92a表达量明显减少。针对以上结果我们推测ROCK可能是miR-92a的上游分子并通过miR-92a影响VSMCs的增殖和迁移。通过体外实验我们发现miR-92a对PDGF-BB呈浓度剂量依赖性变化。ROCK和miR-92a均调节VSMCs的增殖和迁移，pre-miR-92a恢复了Y27632导致的VSMCs增殖和迁移的抑制作用。Y27632（Rho激酶抑制剂）增加了KLF4的表达，siKLF4增加了VSMCs的增殖和迁移。在ROCK-/VSMC中KLF4表达量增加并且应力纤维减少。.结论：ROCK上调miR-92a抑制KLF4的表达，促进PDGF-BB介导的VSMC增殖和迁移，这种新的信号通路可能是改善AS血管功能的治疗药物。