微小RNA-222在运动防治肺动脉高压所致肺血管重构中的作用及机制研究

We previously reported in Cell Metabolism that microRNA-222 (miR-222) is a key regulator contributing to the benefit of exercise in cardiovascular function. Furthermore, we found that miR-222 was significantly downregulated in lung tissues in response to exercise, while upregulated in monocrotaline-induced pulmonary arterial hypertension (PAH). Overexpression of miR-222 could enhance the proliferation of pulmonary arterial smooth muscle cells in vitro. Exercise has been reported to be beneficial for PAH and vascular remodeling. These data suggest that exercise might be able to protect against PAH and vascular remodeling via downregulating miR-222..In this project, we will firstly, based on in vivo (monocrotaline- and hypoxia-induced PAH animal models, using genetic engineering rats or intratracheal injection of adeno-associated virus to regulate miR-222 expression level) and in vitro (pulmonary arterial endothelial cells, smooth muscle cells, and fibroblasts) experiments, clarify the roles of miR-222 in the benefit of exercise in PAH and vascular remodeling. Secondly, based on our previously identified target genes including p27, Hmbox1, HIPK1 and HIPK2, and novel identified target gene TIMP3, we will perform function-rescue assays to elucidate the downstream molecular mechanisms mediating the roles of miR-222 in the benefit of exercise in PAH and vascular remodeling. Our project will identify a novel therapeutic target for PAH and vascular remodeling.

我们先前发表于Cell Metabolism杂志的研究表明，微小RNA-222（miR-222）是一个运动保护心血管的关键微小RNA。进一步发现，miR-222在运动后的肺组织下调，而在野百合碱诱导的肺动脉高压（PAH）模型内上调，过表达miR-222可在体外促进肺动脉平滑肌细胞增殖。运动被报道可以改善PAH所致肺血管重构，提示运动也许可以通过下调miR-222防治PAH所致肺血管重构。本项目拟在动物水平（野百合碱和缺氧诱导PAH，基因工程大鼠或气道注射腺相关病毒干预miR-222）和细胞水平（肺血管内皮细胞、平滑肌细胞和成纤维细胞），明确miR-222和运动防治PAH所致肺血管重构的关系。随后，基于靶基因p27、Hmbox1、HIPK1、HIPK2和TIMP3进行功能挽救实验，阐明miR-222介导运动防治PAH所致肺血管重构的分子基础。本项目将为PAH所致肺血管重构的治疗提供新靶点。

肺血管重构是肺动脉高压特征性的病理改变。临床上肺动脉高压的治疗药物主要起到改善肺血管舒张的功能，尚缺乏有效抵抗肺血管重构的治疗方法。我们先前发表在Cell Metabolism杂志的论著报道了微小RNA-222（miR-222）是一个在运动诱导生理性心肌肥大中上调的微小RNA，本项目的前期工作发现miR-222在运动后的大鼠肺组织中下调，这提示miR-222可能在心脏和肺脏中发挥不同的作用。本项目深入探索miR-222在肺动脉高压及肺血管重构中的功能及作用机制。首先，构建了野百合碱（monocrotaline，MCT）诱导肺动脉高压的模型，miR-222在MCT诱导的肺动脉高压的肺组织中下调。接着，基于miR-222敲除大鼠，发现敲除miR-222可以减轻MCT诱导的肺动脉高压、右心室肥厚及肺血管重构。为了明确抑制miR-222减轻肺动脉高压和肺血管重构的具体机制，我们分离获得了大鼠原代肺动脉平滑肌细胞（PASMC），通过功能学实验发现过表达miR-222促进PASMC的增殖，而抑制miR-222抑制PASMC的增殖，但不影响凋亡。同时，抑制miR-222可以抑制缺氧诱导的大鼠PASMC的增殖和血小板源性生长因子（PDGF-bb）诱导的人PASMC的增殖。最后，我们鉴定出miR-222可以在PASMC负调控P27和TIMP3的表达，P27和TIMP3是miR-222调控PASMC增殖的下游靶基因。综上，本项目明确了抑制miR-222对肺动脉高压和右心室肥厚的保护作用，抑制miR-222可以通过降低PASMC的增殖改善肺血管重构，P27和TIMP3是miR-222调控PASMC增殖的分子基础，本项目的研究为防治肺动脉高压所致肺血管重构提供了新的潜在的干预靶点。