心肌纤维化调控的新机制--M3受体

We have previously demonstrated the important role of M3 subtype muscarinic acetylcholine receptor (M3R) in major heart diseases, because the agonist of M3R or cardiac specific over-expression of M3R has shown protective roles in cardiac ischemia, cardiac hypertrophy and arrhythmia. More recently, our results showed that M3R is also involved in the regulation of myocardial fibrosis and the lncRNA profile was obviously changed in the mouse. However, whether lncRNA regulates the development of myocardial fibrosis through M3R needs to be clarified. Therefore, the present proposal will first investigate the regulatory role of M3R in myocardial fibrosis and explore whether and how M3R is regulated by its related long non-coding RNAs (lncRNAs); and then set up the regulating network between lncRNA-M3R and myocardial fibrosis, through the inner pathways including inflammation, TGF-β1, ERK, and p38 MAPK signaling pathways and their subsequently effect on collagen release and fibrosis; finally, we will explore the prevention or rescue of myocardial fibrosis through interference of M3R or M3R associated lncRNA (M3RANCR). This proposal will be the first time to explore the role of M3R and M3RANCR in regulating myocardial fibrosis and its potential mechanisms, which will provide new understanding and intervention target for major heart diseases.

我们已发现激动或心肌特异性过表达M3受体对心肌缺血、心肌肥厚、心律失常均具有保护作用；证实了M3受体在重大心脏疾病中发挥了关键作用。近期我们发现在小鼠心肌纤维化模型中，心肌组织lncRNA表达谱发生了明显变化；激动M3受体对心肌纤维化有调控作用。然而，M3受体对心肌纤维化的调控机制及lncRNA在其中的具体作用并不十分清楚。本课题揭示lncRNA（M3RANCR）-M3受体对心肌纤维化的调控作用，建立lncRNA-M3受体对心肌纤维化作用的网络，并检测炎症反应、TGF-β1、ERK、p38 MAPK等信号通路在调控心肌成纤维细胞胶原分泌和纤维化进程中的作用；探索干预lncRNA-M3受体网络防控心肌纤维化的新机制。首次探索lncRNA调控M3受体在心肌纤维化中的作用及机制，为重大心脏疾病提供新理论和干预靶点。

心脏纤维化是导致心脏疾病恶化和心衰发生发展的主要原因。M3受体（M3R）参与多种心脏疾病的病理生理过程，然而其与心脏纤维化的关系尚不清楚。本项目采用分子生物学、组织形态学及心动超声术等技术在体内、体外水平研究心脏M3R抗心脏纤维化的作用及分子机制。本项目主要完成内容：1）揭示了M3R抗心脏纤维化的作用及分子机制。发现胆碱通过激活M3R抑制TGF-β1/Smad和p38 MAPK信号通路，抑制心脏成纤维细胞活化和胶原分泌，进而抑制压力超负荷诱导的小鼠心脏纤维化，改善心脏功能；而M3R阻断剂可逆转胆碱抗纤维化作用。2）发现M3R活化的新上游调控分子-G蛋白信号调节因子4（RGS4）。过表达RGS4抑制M3R表达，减弱胆碱对小鼠心脏纤维化水平的抑制作用，而沉默RGS4通过激活M3R抑制小鼠缺血诱导的心脏纤维化，其抗纤维化机制与抑制TGF-β1/Smad和p38 MAPK信号通路有关。3）揭示了M3R通过上调miR-29b表达，抑制下游促纤维化蛋白BACE1表达抗心脏纤维化的新机制。本项目的完成阐明了M3R抗心脏纤维化的作用及分子机制，完善了M3R参与调节心脏纤维化上下游分子信号网络，为心脏纤维化疾病的防治提供新靶点。