HuR对p62的mRNA稳定性调控机制在低氧性肺动脉高压肺动脉平滑肌细胞损伤中作用

The proliferation and inflammation of pulmonary arterial smooth muscle cells (PASMCs) play the key role in the pathogenesis of hypoxic pulmonary hypertension (HPH), while the precise mechanism is not fully elucidated. Related studies suggested that HuR-mediated mRNA stability control participated in the progress of multiple proliferative and inflammatory diseases. Our previous studies also demonstrated that altered expression and activity of HuR is a key mechanism underlying asthmatic airway smooth muscle cells proliferation. Whether HuR-mediated mRNA stability regulation is also involved in HPH-associated PASMCs dysfunction is not known. p62 is a newly-identified HuR target molecular, and recent studies demonstrated that p62 could affect cell inflammation and growth via interacting with multiple cellular signal pathways, such as NF-κB signaling and mTOR signaling. Based on these findings, we hypothesized that HuR-mediated p62 mRNA stability regulation might also participate in HPH-associated PASMCs dysfunction. In the present study, the role of HuR-mediated p62 mRNA stability regulation will be investigated using both in-vivo and in-vitro methods. Then the possible downstream mechanism of p62 in HPH-induced PASMCs inflammation and proliferation will be explored. The present study might not only help to better the current understanding of HPH-induced PASMCs inflammation and proliferation, and might help to explore novel intervening method as well.

肺动脉平滑肌细胞（PASMCs）的增殖和炎症是低氧性肺动脉高压的重要特征，也是干预的重要靶点。相关研究提示：HuR及其介导的mRNA的稳定性调控机制与多种炎症性、增生性疾病发生有关。项目组前期研究发现，HuR表达及活性增加参与哮喘状态下气道平滑肌细胞增殖的发生。HuR在PASMCs增殖和炎症中的作用目前尚不清楚。新近研究发现，p62作为一种HuR靶分子，可通过NF-κB以及mTOR信号通路在细胞炎症反应、细胞周期调控发挥调节作用。根据上述研究，本课题主要探讨以下两个主要问题：（1）HPH发病过程中，p62能否作为HuR的下游靶分子参与PASMCs形态功能异常的发生。（2）p62能否通过NF-κB以及mTOR信号通路参与HPH状态下PASMCs的细胞增殖、炎症反应过程。本项目对于深入理解HPH状态下PASMCs的细胞增殖炎症反应的机制以及寻找可能的干预措施均具有重要意义。

本研究主要研究内容：HuR在低氧性肺动脉高压（HPH）状态下对肺动脉平滑肌细胞（PASMCs）炎症过程的调控机制。本研究发现在PASMCs中低氧可以增加HuR蛋白水平，降低p62蛋白水平。慢性阻塞性肺疾病（COPD）患者存在的持续性低氧状态引起的肺动脉高压是最常见的低氧性肺动脉高压的基础病因，因此我们进一步研究了COPD患者发生低氧和肺动脉高压的机制及其影响因素。既往有研究认为HuR表达水平与身体质量指数（BMI）成负相关，同时我们在COPD患者人群中也发现（1）吸烟患者气道上皮中HuR水平较非吸烟者增高，体外实验发现在气道上皮细胞（AEC）中HuR通过增加ZEB-1的表达来促进香烟烟雾萃取液（CSE）诱导的EMT；（2）不同BMI分级与肺动脉压高低有一定相关趋势，其中低BMI患者因呼吸肌力差，肺功能更差，缺氧严重，肺动脉压更高，而高BMI患者呼吸肌力强，肺功能较好，缺氧较轻，肺动脉压相对较低。提示在COPD患者中与HuR相关的BMI水平存在“肥胖悖论”。而对于这种悖论机制的研究中我们发现高胰岛素刺激可以通过激活自噬减缓CSE刺激气道上皮细胞而诱导的细胞衰老。吸烟和高血糖共刺激可以通过TGF-β/Smad途径激活AEC的EMT，从而激活小气道重塑。我们的研究进一步证实了包括HuR、p62在内的多种蛋白可能在不同水平参与了COPD相关HPH的发生发展，这为寻找干预HPH的重要靶点以及深入探讨HPH的发生机制提供了重要的理论依据。