PDGF-BB通过甲基化修饰下调miR-328在肺动脉高压形成中的作用及分子机制

Pulmonary arterial hypertension (PAH) is a complicated vascular disease, characterized by abnormal proliferation of pulmonary artery smooth muscle cell (PASMC) and pulmonary vascular structural remolding. Platelet-derived growth factor (PDGF) plays an important role in the development of PAH, however, the underlying molecular mechanism is not fully understood. According to preliminary miRNA profiling and quantitative PCR analysis, we found that the expression of miR-328 was significantly down-regulated by PDGF-BB treatment, displaying a time and concentration dependent manner. Moreover, we observed miR-328 is functionally associated with PASMC proliferation, and PIM-1 is a direct target gene of miR-328. Based on these results, we hypothesize that miR-328 might involve in the development of PDGF-BB induced PAH. In this proposal, we will further investigate: 1) the molecular mechenism of PDGF-BB induced downregulation of miR-328; 2) the biological functions of miR-328 in PDGF-BB related PASMC poliferation and PAH development; 3) the impact of synthetic miR-328 agomir on PAH symtoms in hypoxia induced rat model. Overall, by integrating the findings from both in vitro and in vivo levels, this project will precisely reveal the functions and mechanisms of miR-328 in PDGF-BB induced PAH, aiming to find new cues for studying the pathogenesis of PAH and new PAH therapeutic targets.

肺动脉高压(PAH)发病机制复杂，其主要病理症状是肺动脉平滑肌细胞(PASMC)异常增殖和肺血管结构重建。血小板衍生因子(PDGF)是PAH发生的重要诱因，但其作用的分子机理尚不完全清楚。前期表达谱及定量PCR分析发现，PDGF-BB显著下调miR-328表达，并表现时间和浓度依赖性。功能上miR-328与PASMC增殖相关，且其靶基因是PIM-1。根据前期结果推测，miR-328参与调控PDGF-BB诱发的PAH。基于此，本项目将深入研究1) PDGF-BB下调miR-328表达的分子机理，2) miR-328在PDGF-BB刺激PASMC中的功能和作用机制, 3) 在大鼠模型中导入miR-328对PAH症状的改善作用。本项目将综合离体和活体两个层面的研究结果，力图精确的揭示miR-328在PDGF-BB诱发PAH形成中的功能及作用机制，为解析PAH的发病机理和寻找新的治疗靶点提供思路。

血小板衍生生长因子（PDGF）是血管平滑肌细胞最强的致有丝分裂原和趋化因子。PDGF信号通路的异常能够诱导肺动脉平滑肌细胞异常增殖和迁移，促进肺动脉高压的形成。miRNA是一类对细胞功能具有重要调控作用的非编码小RNA，然而miRNA是否介导PDGF信号传导从而调节平滑肌细胞的功能还不清楚。本项目主要研究了在PDGFBB刺激肺动脉平滑肌细胞下，具有显著表达变化的miRNA，及其对细胞功能异常的调控作用及分子机制。我们首先通过表达谱筛选获得了一系列受PDGFBB显著调节的miRNA，并对其中三个显著下调的miRNA，包括miR-328，miR-4632以及miR-1181进行深入研究，主要研究结果发现：1) PDGF下调miR-328表达与DNA甲基化修饰相关，而miR-328通过其靶基因Pim-1调节平滑肌细胞增殖和迁移的功能；2) PDGF下调miR-4632与去乙酰化修饰相关，miR-4632通过靶向cJUN调节细胞增殖和凋亡；3) miR-1181/STAT3调节轴介导了PDGFBB对平滑细胞增殖和迁移的影响；4) 肺动脉高压血清中分析发现3个miRNAs表达均下调。本项目研究工作的完成，为PDGFBB通过miRNA调节平滑肌细胞功能异常的分子机制提供了初步的理论结果。