PDGF通过激活HDAC下调miR-4632在肺动脉高压形成中的作用及机制研究

The hyperproliferation of pulmonary arterial smooth muscle cells (PASMC) is an important cause of pulmonary vascular remodeling and pulmonary arterial hypertension (PAH). The excessive proliferation of PASMC induced by platelet-derived growth factor (PDGF) plays a critical role in the pathogenesis of PAH, but the mechanism by which miRNA is involved in the regulation is not completely understood. Based on our previous study, we hypothesis that miR-4632 may be regulated by epigenetic regulation of PDGF-activated histone deacetylase (HDAC) and participate in the proliferation and apoptosis of PASMC by targeting c-Jun. The project will continue to carry out the following studies: (1) To investigate the effect of miR-4632 on proliferation and apoptosis of PASMC and on pulmonary vascular remodeling; (2) To make clear whether the target gene c-Jun mediates the function of miR-4632 in PASMC; (3) To elucidate the molecular mechanism by which miR-4632 downregulated by PDGF-mediated activation of HDAC. Through systematic study on the function, regulaional mechanism and self regulation of transcription, we try to explain the relationship between abnormal expression of miR-4632 and PAH. Generally, this project would provide a new insight into the pathogenesis of PAH and provide new clues for development of targeted therapies.

肺动脉平滑肌细胞（PASMC）的过度增殖是引起肺血管重构和肺动脉高压（PAH）的重要原因。血小板衍生生长因子（PDGF）促进PASMC异常增殖是重要的病理机制，但miRNA参与调控这一过程的机理尚不完全清楚。本项目在前期研究基础上提出miR-4632可能受PDGF激活的组蛋白去乙酰化酶（HDAC）的表观遗传调控，并通过靶基因c-Jun参与对PASMC增殖和凋亡的调节。项目后续将开展如下研究：（1）探讨miR-4632对PASMC增殖、凋亡，以及对肺血管重构的影响；（2）明确靶基因c-Jun是否介导了miR-4632 在PASMC中的功能；（3）阐释PDGF激活HDAC下调miR-4632的分子机制。通过系统研究miR-4632的功能、作用机制及自身的表达调控，揭示miR-4632异常表达与PAH之间的关系，为更全面解析PAH的发病机理和研发新的靶向药物提供线索。

背景：肺动脉平滑肌细胞（PASMC）异常增殖和迁移引发肺动脉血管重构是PAH的重要病理基础。血小板衍生生长因子（PDGF）是PASMC的一种重要的促有丝分裂原，与肺动脉血管重构密切相关。microRNA（miRNA）是一类非编码单链小RNA，通过与靶基因3`非翻译区相互作用，在转录后水平抑制目的基因的表达。近期的研究表明，PDGF调控的miRNAs在调控PASMC的细胞功能和介导PDGF刺激的细胞高增殖状态中起着关键作用。.方法和结果：前期的miRNA表达谱分析发现，miR-4632是在PDGF-BB处理的PASMC中下调最显著的miRNA。我们发现miR-4632在PASMC中高丰度表达，并且在促进PAH发生的不同刺激条件下其表达量都显著降低。功能研究表明miR-4632抑制PASMC增殖，促进细胞凋亡，但对细胞收缩和迁移无影响。生物信息学预测和3'-非翻译区报告基因分析证实，c-Jun是miR-4632的靶基因。挽救实验证实，过表达c-Jun可以逆转miR-4632的过表达对PASMC增殖的抑制作用，提示miR-4632对c-Jun的靶向抑制对于其介导的PASMC异常增殖和凋亡是必需的。此外，PDGF-BB对miR-4632的下调与组蛋白去乙酰化有关，是通过激活PDGF受体/PI3K/HDAC4信号传导途径实现的。此外，临床样本分析发现，在先天性心脏病合并肺动脉高压(CHD-PAH)患者的血清中miR-4632的表达水平显著降低。.结论：我们阐释了一种全新的、整合了多种表观遗传调节因子的调控途径，即PI3K-HDAC4-miR-4632，并证明其通过靶基因c-Jun参与调节PDGF-BB诱导的PASMC的增殖和凋亡。这些数据提示，miR-4632可能作为一种潜在的生物标志物和小分子药物应用于PAH的诊断和治疗。