AQP1在低氧性肺动脉高压发病过程中的作用机制研究

The changes that occur in the pulmonary circulation with exposure to chronic hypoxia include reductions in pulmonary arterial diameter due to contraction and structural remodeling of vasculature, which result in increased pulmonary vascular resistance and the development of pulmonary hypertension (PH). The vascular remodeling that occurs in the lung is due to migration, imbalance of apoptosis and proliferation of pulmonary arterial smooth muscle cells (PASMCs). AQP1 was the first family member identified and has since been shown to aid in the migration of epithelial, endothelial and tumor cells. Peroxisome proliferators activated receptor gamma (PPAR-γ) plays a very important role in the development of PH, but the exact mechanisms and downstream signal pathway remain incompletely understood. Our previous studies demonstrated that modulating the expression of AQP1 altered the migratory and proliferative capacity of PASMCs, and the C-terminal tail of AQP1 was critically important for AQP1-mediated migration and proliferation. What is the exact mechanism of AQP1-mediated pulmonary artery remodeling? Is AQP1 the key molecule of PH? We hypothesize that PPAR-γ can regulate AQP1, and AQP1 can increase the PASMCs migration and proliferation via inhibiting cell apoptosis. We will analyze AQP1 signal pathway by using silencing and overexpression techniques, AQP1 knockout mice to explore the role of AQP1 in mediating pulmonary vascular remodeling during the development of PH.

慢性缺氧可导致肺血管收缩内径减小，并发生血管重塑，从而导致肺动脉高压（PH）。肺动脉的血管重塑，可能是由于肺动脉平滑肌细胞（PASMCs）的迁移、凋亡和增殖的不平衡造成。有文献报道水通道蛋白1（AQP1）可促进上皮细胞、内皮细胞以及一些肿瘤细胞的迁移。过氧化物酶体增殖激活受体γ（PPAR-γ）对肺动脉高压的发生具有重要作用，但其具体的调控机制尚未完全阐明。申请人在博士期间的研究发现在体外AQP1可促进PASMCs的增殖和迁移，并与其C尾有关（AJRCMB, 2014）。AQP1导致肺动脉重塑的机制是什么，AQP1是否是导致PH的关键分子？由此我们提出假设：PPAR-γ可能调控AQP1的表达，AQP1可能促进PASMCs的迁移，并通过抑制细胞凋亡导致PASMCs的过度增殖，最终导致PH。我们将采用AQP1敲除小鼠、腺病毒过表达、RNA干扰等分析相关信号通路，探索AQP1导致PH的相关机制。

暴露在缺氧环境中可导致肺动脉平滑肌细胞（Pulmonary arterial smooth muscle cells, PASMCs）的增殖和迁移，从而导致血管重塑及缺氧性肺动脉高压的发生。前期研究已发现水通道蛋白1（Aquaporin 1, AQP1）在PASMC的增殖与迁移中具有重要作用，但具体机制尚不清楚。在肿瘤、肾脏及干细胞中，AQP1可与β-连环蛋白（β-catenin）相结合，β-catenin可激活某些与细胞增殖及迁移的基因（如c-Myc和cyclin D1）的转录。本研究主要以β-catenin为核心探讨AQP1介导PASMC增殖与迁移的相关机制。本研究用含有绿色荧光蛋白的腺病毒载体（对照AdGFP）、野生型AQP1（AdAQP1）、去除C尾的AQP1（AdAQP1M），感染大鼠PASMC。我们发现：（1）过表达AQP1可在mRNA及蛋白水平上调β-catenin及其靶基因c-Myc和cyclin D1的表达，而过表达AdAQP1M并不能上调β-catenin及其靶基因的表达；（2）采用siRNA的方法敲除β-catenin可抑制缺氧及AQP1介导的PASMC的增殖及迁移，以及c-Myc和cyclin D1表达的增加。本研究证实AQP1可促进β-catenin及其靶基因的表达，并且促进PASMC的增殖与迁移，这一机制与AQP1的C尾相关。