MicroRNA-424促动脉粥样硬化及异黄酮对其抑制作用的机制研究

Accumulating data from molecular studies and animal studies have shown that circulating monocytes differentiating into macrophages in the sub-endothelial space is one of the pivotal steps in the development of atherosclerosis. Whether microRNAs play roles in the differentiation of monocytes into macrophages have been still unknown. We determined the expression level of miR-424 and found it was obviously increased in the peripheral blood monocytes in patients with coronary artery disease and the ox-LDL induced monocytes in vitro. Therefore, we hypothesized that miR-424 might promote the progression of atherosclerosis by inhibiting the expression of its target protein NFI-A and activating the NF-kB pathway. Meanwhile, based on the fact that isoflavone is one of the agonists of PPARγ, we hypothesized that isoflavone might reduce the expression level of miR-424 in monocytes to inhibit the NF-kB pathway and the progression of atherosclerosis. In the present study, we will investigate whether miR-424 can activate the NF-kB pathway and promote the progression of atherosclerosis in vitro and in vivo. Next, isoflavone will be used in vitro and in vivo to clarify whether the expression of miR-424 and NF-kB pathway can be inhibited. Furthermore, the promoter of miR-424 will be conducted and the hypothesis that isoflavone might inhibit the transcription of miR-424 in monocytes as one of the agonists of PPARγ will be also confirmed.

单核-巨噬细胞分化是动脉粥样硬化的一个重要环节，microRNA在其中是否发挥调控作用，目前研究较少。我们前期研究发现，冠心病患者外周单核细胞及体外培养的ox-LDL诱导的单核细胞中miR-424表达均显著升高，而加入异黄酮后，体外miR-424表达显著受抑。因此，我们推测miR-424可能通过抑制其靶蛋白NFI-A，激活了NF-kB信号转导通路，促进了单核-巨噬细胞的分化及动脉粥样硬化的发展。同时，依据异黄酮是PPARγ激动剂这一事实，猜测异黄酮可能经激动核转录因子PPARγ抑制了miR-424的表达。本课题拟从体内、体外及高、低表达等研究方向探讨miR-424促动脉粥样硬化的作用机制。然后应用异黄酮从体内、体外分别进行干预，观察miR-424的表达是否受抑。最后，构建miR-424启动子以明确异黄酮抑制miR-424转录表达的机制，为动脉粥样硬化研究提供新的理论依据及靶点。

单核-巨噬细胞分化是动脉粥样硬化的一个重要环节，microRNA在其中是否发挥调控作用，目前研究较少。冠心病患者外周单核细胞及体外培养的ox-LDL诱导的单核细胞中miR-424表达均显著升高，而加入异黄酮后，体外miR-424表达显著受抑。因此，我们推测miR-424可能通过抑制其靶蛋白NFI-A，激活了NF-kB信号转导通路，促进了单核-巨噬细胞的分化及动脉粥样硬化的发展。同时，依据异黄酮是PPARγ激动剂这一事实，猜测异黄酮可能经激动核转录因子PPARγ抑制了miR-424的表达。本课题研究结果显示：冠心病患者单核细胞中miR-424表达增加，抑制了靶蛋白NFI-A的表达，NFI-A蛋白的减少进而促进了单核-巨噬细胞的分化，推动了动脉粥样硬化的发生发展。体外培养的单核-巨噬细胞分化过程中，miR-424的表达可以被异黄酮显著抑制。体内研究显示，喂养异黄酮的小鼠与安慰剂喂养的小鼠比较，其体内miR-424的表达显著减低，NFI-A蛋白明显增多，由此导致其炎性标志物IL-6、TNF-α浓度减低，动脉粥样硬化被显著抑制。体内、体外研究均提示异黄酮可以抑制miR-424的表达并抑制动脉粥样硬化的进展。.本课题历时三年，目前已发表SCI文章1篇，在审SCI文章2篇（其中1篇已经修回），按时达到预期目标。