ANXA2异四聚化调控AT1R再循环在PASMCs表型转换中的机制研究

Pulmonary vascular remodeling is the key change in various vascular diseases, and phenotypic modulation of pulmonary arterial smooth muscle cells（PASMCs）is a key pathophysiological component in pulmonary vascular remodeling. However, the mechanism of pathogenesis worth further study. On the basis of our investigations, we found that angiotensin II type 1 receptor(AT1R) might be greatly valuable for study on molecular mechanism of annexin A2（ANXA2） mediated- PASMCs phenotypic modulation. According to literature, we propose that AT1R continuously activate through recycling, which is an important mechanism of PASMCs phenotypic modulation; and ANXA2 play a key regulatory role in AT1R recycling via heterotetramerization. In this study, we plan to use PASMCs model for in vitro studies and apply immunofluorescence, immunolabelling, laser confocal microscopy and fluorescence resonance energy transfer to observe PASMCs phenotypic change following treatment with hypoxia and hepatopulmonary syndrome（HPS）rat serum, and measure ANXA2 heterotetramerization, AT1R recycling and its expression, subsquently, to identify the role in regulating AT1R recycling by disrupting ANXA2 heterotetramerization, thereby, to elucidate the role and mechanism of AT1R recycling in PASMCs phenotypic modulation, and further to establish a new strategy with pulmonary vascular remodeling.

肺血管重建是多种血管性疾病的核心变化，其中肺动脉平滑肌细胞（PASMCs）表型转换是其病理基础，但发病机制有待进一步阐明。本项目组在前期研究的基础上，发现血管紧张素II-1型受体（AT1R）可能在膜联蛋白A2（ANXA2）介导的PASMCs表型转换分子机制中有重要研究价值，结合文献推测：AT1R通过再循环持续活化，是PASMCs表型转换的重要机制，且ANXA2通过异四聚化对AT1R再循环发挥关键性调控作用。本项目拟建立离体PASMCs模型，采用免疫荧光、免疫标记、激光共聚焦及荧光共振能量转移等方法观察低氧、肝肺综合症（HPS）大鼠血清处理后PASMCs表型改变，检测ATIR表达变化、AT1R再循环情况及ANXA2异四聚化状态；并通过抑制ANXA2异四聚化，研究其对AT1R再循环的调控作用，阐明AT1R再循环在PASMCs表型转换发生中的作用及机制，为肺血管重建的防治提供新策略。

肺血管重建是多种血管性疾病的核心变化，其中肺动脉平滑肌细胞（PASMCs）表型转换是其病理基础，但发病机制有待进一步阐明。本项目组在前期研究的基础上，发现血管紧张素II-1型受体（AT1R）可能在膜联蛋白A2（ANXA2）介导的PASMCs表型转换分子机制中有重要研究价值。本项目建立了离体PASMCs模型，采用免疫荧光、免疫标记、激光共聚焦等技术研究发现：1、Annexin A2 (ANXA2)介导HPS血清致PASMCs增殖与Caveolae/Caveolin-1（Cav-1）有关；2、ANXA2通过Cav-1/Rac1/F-actin介导肝肺综合征肺微血管重建；3、Aquaporin 1（AQP1）参与ANXA2介导HPS血清致PASMCs迁移。上述研究结果证实Cav-1介导的应力纤维形成可能是ANXA2介导AT1R再循环过程中的重要环节，细胞膜AQP1通过调控细胞骨架重构参与ANXA2介导AT1R再循环。阐明了ANXA2在PASMCs表型转换发生中的作用及机制，为肺血管重建的防治提供新策略。