衰老诱发动脉粥样硬化新机制——lncRNA-MALAT1调控血管内皮-间质转化

Aging is becoming a key social problem in China. The mechanism of age-related cardiovascular diseases mainly caused by atherosclerosis is still unclear. Endothelial dysfunction is a key early stage of atherosclerotic plaque formation. In the present study, we for the first time found that during aging, endothelial cells undergo endothelial-mesenchymal transition (EndMT) and result in high endothelial permeability. LncRNA play crucial roles in many pathophysiological processes. To our knowledge, LncRNA has not been previously described in regulating EndMT and the mechanism by which LncRNA regulates atherosclerosis is unclear. We conducted molecular biological experiments along with bioinformatics analysis and found MALAT1 and its probable upstream regulator SIRT6 may be involved in aging induced EndMT. Next we will further examine the effect of EndMT reversal on the repression of age-related atherosclerosis in vitro and in vivo. For the first time, our program puts forward the idea that regulating EndMT through LncRNA is expected to be an effective treatment for age-related atherosclerosis. Our program will provide important clues for the prevention and treatment of age-related cardiovascular diseases.

我国老龄化问题已迫在眉睫，而由于动脉粥样硬化病变引起的衰老相关心血管疾病的发生机制还不清楚，并已成为本领域研究难点问题。血管老化导致内皮功能障碍是动脉粥样硬化形成的早期关键环节，我们前期研究首次发现血管内皮在衰老过程中发生内皮-间质转化现象（EndMT），导致内皮细胞间粘附力减弱，收缩力增强，血管内膜通透性增大，lncRNA参与细胞多种进程调控，但其介导衰老诱发动脉内皮EndMT及粥样硬化的关键机制尚不清楚，其调控靶点及上下游通路如何，这些都是亟待解决的重点问题。本项目采用分子生物学结合生物信息学分析筛选出衰老诱发EndMT可能的介导分子MALAT1及其上游转录因子SIRT6，并在体内外模型验证逆转EndMT对衰老动脉粥样硬化的防治作用。本项目首次提出以lncRNA为靶点调控EndMT过程防治衰老动脉粥样硬化新理念，将为老年人心血管疾病防治提供新的治疗靶点和思路，具有很强的理论指导意义。

本项目按计划任务书顺利完成。我国老龄化问题日趋严峻，动脉粥样硬化是引起衰老相关心血管疾病的主要病变之一。内皮向间质转化（Endothelial to mesenchymal transition，EndMT），是内皮细胞失去内皮表型而获得间充质表型的转变过程，是动脉粥样硬化发生的关键环节。本研究目的在于探究衰老是否可以诱导血管内皮细胞发生EndMT。实验发现与2月龄的小鼠相比，18月龄的ApoE-/-小鼠动脉出现明显的粥样斑块。18月龄小鼠的主动脉内膜处内皮细胞特异性分子CD31和VE-cadherin表达降低，间质细胞特异性分子α-SMA和smMHC表达升高，证明衰老的血管内膜内皮细胞发生了EndMT，体外培养的HAEC在复制性衰老过程中也呈现EndMT转变。与年轻细胞相比，lncRNA-MALAT1在衰老的内皮细胞中表达明显升高，干扰MALAT1表达可下调转录因子Snail的表达，进而逆转衰老诱发的EndMT。ChIPbase网站数据显示MALAT1的启动子区域有去乙酰化酶SIRT6的结合位点，SIRT6蛋白在内皮衰老过程中表达下降并可结合在MALAT1的启动子区域并负向调控MALAT1的表达。因此我们得到结论，衰老通过SIRT6/MALAT1/Snail信号通路诱发EndMT，最终导致动脉粥样硬化病变，这一发现将为老年人心血管疾病防治提供新的治疗靶点和思路。除此以外，我们还发现内皮细胞焦亡在动脉粥样硬化的过程中发挥关键作用，褪黑素可以通过靶向MEG3/miR-223/NLRP3抑制内皮细胞焦亡，进而延缓动脉粥样硬化进程，这一研究为动脉粥样硬化临床治疗提供了新的治疗药物。尼古丁通过ROS/NLRP3信号通路介导内皮细胞焦亡，阻断ROS/NLRP3通路可改善由尼古丁诱发的血管内皮细胞焦亡，改善动脉粥样硬化症状。