周期性张应力下NOTCH1低表达加剧主动脉平滑肌细胞线粒体功能障碍的机制及干预研究

NOTCH1或其他基因缺陷所致的二叶式主动脉瓣畸形（BAV）患者发生升主动脉瘤的风险是普通人的80倍。目前临床诊疗的难点包括手术时机存在争议、缺乏控制病变的有效药物。其根源在于致病机制复杂，而实验研究中存在技术瓶颈：兼具BAV和主动脉瘤两个特征的动物模型难以构建；常规体外细胞模型无法重现体内主动脉细胞所受的生物机械力刺激。针对体外细胞模型的不足，前期工作中建立了基于微生理系统的实验模型，并发现NOTCH1基因参与调控主动脉平滑肌细胞的表型改变及凋亡是通过线粒体发挥作用的。本项目拟进一步确认，在周期性张应力培养条件下NOTCH1基因和线粒体分裂-融合平衡之间的相互关系，探究基因型和表型的关联影响及内在机制；使用线粒体分裂抑制剂以及融合激活剂，验证其对于逆转线粒体功能障碍，以及抑制细胞表型改变和细胞凋亡的干预作用。本研究有助于深入理解BAV相关主动脉病变的发病机制和寻找潜在治疗靶点。

Patients with bicuspid aortic valve (BAV) caused by NOTCH1 mutation or other genetic defects have 80-fold increased risks of developing ascending aortic aneurysm. Difficulties in clinical diagnosis and treatment include flawed indication for prophylactic surgery, and a lack of effective drugs to control aortopathy. Those difficulties arise from the complex pathogenic mechanisms of BAV, for which the conventional experimental models have several technical bottlenecks: a) animal models with both characteristics of BAV and aortic dilatation are difficult to construct, and b) in vitro cell models cannot simulate the biomechanical stimuli sensed by aortic cells during cyclic systole and diastole in vivo. To address the limitations of the in vitro cell models, we established a microphysiological system that cultured human aortic smooth muscle cell under cyclic tensile stress, and the preliminary data showed that NOTCH1 regulated phenotypic changes and apoptosis of smooth muscle cell via function of the mitochondria. In this project, we aim to validate the function of NOTCH1 in maintaining the mitochondrial fission-fusion balance, and to explore the interconnection between genotypic and phenotypic changes and the underlying mechanism. Furthermore, the mitochondrial fission inhibitors and fusion activators will be introduced to the models to verify their effects on reversing mitochondrial dysfunction, inhibiting phenotypic changes and reducing apoptosis. This project will extend our knowledge of the mechanism of BAV-related aortopathy and its potential therapeutic targets.