端粒酶活性的动态调控在血管钙化和重构中的作用机制研究

Vascular calcification, highly correlated with cardiovascular disease mortality, is recognized as an active and regulated biological process involving osteoblast-like cell transdifferentiation of vascular smooth muscle cells. Several mechanisms to explain vascular calcification have been identified including loss of inhibition, induction of bone formation, circulating nucleation complexes, and cell death. However, the precise mechanism of vascular calcification is still unclear. .There is wide inter-individual variation in the risk of developing age-associated diseases, such as vascular calcification, atherosclerosis, and cardiovascular disease. Telomere length has emerged as a marker that represents biological aging which is the key to age-related diseases. Recent evidence have shown that heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) can bind telomeric DNA and remarkably enhance the catalytic activity of telomerase in tumor cells in vitro assays. A growing number of studies suggest that development of atherosclerosis at the earliest stage is associated with telomerase activation. However, the role of telomere shortening in the pathogenesis of artery calcification has rarely been investigated. .In the present study, we aimed to (1) study the regulatory role of hnRNP A1 in telomere length, telomerase activity, and osteoblast-like cell transdifferentiation of vascular smooth muscle cells, via in vitro cell culture and in vivo ApoE-/- atherosclerotic mice model; (2) explore the mechanisms that cell senescence regulates vascular remodeling via the expression of hnRNP A1 and telomerase activity; (3) investigate the relation between telomere length, telomerase activity and the development and progression of coronary artery calcification in a large case-control study.

动脉钙化与老龄化相关，是心脑血管疾病高发病率和高死亡率的重要因素之一。前期工作发现血管平滑肌细胞分化为成骨细胞表型时，端粒酶活性显著增加，骨桥蛋白表达增加，这一过程受到核不均一核糖核蛋白hnRNP A1的调节，提示端粒酶的动态调控在动脉粥样硬化血管钙化中可能有重要作用。本项目采用分子生物学、影像和群体遗传学等手段，拟解决关键科学问题1： 通过体外细胞培养和ApoE-/-动脉粥样硬化小鼠模型，siRN功能阻断和基因过表达等技术，研究血管钙化和重塑过程中hnRNP A1和端粒酶活性、骨桥蛋白等的表达规律；问题2：细胞老化对hnRNP A1和端粒酶活性的负调控机制及其对血管重塑的影响；问题3：检测端粒和端粒酶活性与中国人群血管钙化、钙化评分及钙化进展的关系，评估端粒在血管钙化和心血管事件中的预警价值。本项目将为阐明血管平滑肌细胞表型分化和老化凋亡引起血管钙化重构异常的机制提供新的依据和干预靶点。

动脉钙化与老龄化相关，是心脑血管疾病高发病率和高死亡率的重要因素之一。单核/巨噬细胞激活是动脉粥样硬化发生发展的关键核心，斑块内的巨噬细胞活动可以引起活跃的炎症反应、纤维帽平滑肌细胞钙化和脂质堆积等，最终导致斑块破裂，诱发心脑血管事件。本项目研究miR-216a调控巨噬细胞端粒酶激活的分子机制，阐明其对巨噬细胞分化和功能的影响，为动脉粥样硬化性心血管疾病的治疗提供新的理论依据。结果发现（1）人颈动脉内膜剥脱斑块部位的巨噬细胞端粒酶活性显著上调；（2）通过体外细胞培养和ApoE-/-动脉粥样硬化小鼠模型，发现miR-216a促进巨噬细胞分化过程中端粒酶激活，这一过程通过Smad3/NF-κB信号通路介导；反之，抑制miR-216a可能通过下调端粒酶活性，减弱巨噬细胞活性和炎性反应，延缓斑块进展。（3）与冠脉稳定斑块组比较，有不稳定冠脉斑块的患者血浆miR-216a表达水平显著增加，提示miR-216a可能成为预测动脉粥样硬化相关心血管事件的生物标志物。.本项目研究结果参加国际学术会议交流2次。培养硕士研究生2名，博士研究生2名。