NF2/Merlin通过Hippo/YAP-Parkin途径调控糖尿病心肌纤维化的作用研究

Diabetic cardiomyopathy (DCM) usually leads to myocardial fibrosis, and increases the hospitalization and mortality rate of diabetic patients. The proliferation and activation of cardiac fibroblasts (CFs) play a key role in the genesis and development of myocardial fibrosis caused by DCM. Previous studies have shown that NF2/Merlin regulates the biological behaviors of CFs via Hippo/YAP signal pathway. When Merlin is phosphorylated or NF2 deficiency/mutation occurs, YAP will be dephosphorylated and enter the nucleus to combine with regulatory factors and promote the expression of downstream target genes, thus further promoting cell proliferation. Evidences suggested that a large number of mitochondria with complete structure could provide energy for CFs proliferation and activation. The quality and quantity of mitochondria are balanced by mitophagy. Under the circumstance of mitochondria damage, PINK1 will collect Parkin from cytoplasm to locate the mitochondria and cell functions are maintained by increasing of mitophagy. Therefore, we hypothesized that NF2/Merlin- Hippo/YAP-Parkin may participate in the genesis and development of DCM myocardial fibrosis via regulating CFs proliferation and activation. To verify the hypothesis, this project proposed to use CFs specificity NF2 gene knockout mice (NF2 cf KO) as the object of study and establish a mice DCM model to reveal the effect and mechanism of NF2 in DCM myocardial fibrosis, and thus to provide important theoretical guidance and new therapeutic strategy for myocardial fibrosis caused by DCM.

糖尿病心肌病(DCM)心肌纤维化增加糖尿病患者死亡率。心脏成纤维细胞(CFs)的增殖、活化是DCM心肌纤维化发生发展的关键环节。我们前期发现，NF2编码的Merlin经由Hippo/YAP信号通路实现对CFs的调控。Merlin磷酸化或NF2缺失、突变时，YAP去磷酸化，从而促进CFs增殖与活化。文献表明，CFs的增殖与活化需要线粒体提供能量，而线粒体的质量和数量由线粒体自噬来平衡。线粒体损伤时，PINK1募集Parkin定位到线粒体，通过增加线粒体自噬维护细胞功能。因此我们推测：NF2/Merlin可能通过Hippo/YAP-Parkin途径调控DCM心肌纤维化。本项目拟采用CFs特异性NF2基因敲除小鼠建立DCM模型，揭示NF2在DCM心肌纤维化中的作用，阐明NF2通过Hippo通路及Parkin介导的线粒体自噬调控CFs增殖与活化的分子机制，为优化DCM心肌纤维化治疗策略提供新思路。

我们前期发现，NF2编码的Merlin经由Hippo/YAP信号通路实现对心脏成纤维细胞（CFs）的调控。我们采用CFs特异性NF2基因敲除小鼠构建立糖尿病心肌病（DCM）模型，探讨了NF2在DCM心肌纤维化中的作用：CFs特异性NF2基因敲除小鼠在DCM模型建立后表现为心脏纤维化面积增加、胶原分泌增加、线粒体自噬水平增加；体外高糖高脂干预后CF增殖和活化增加，NF2表达降低，p-YAP表达下降，YAP表达增加。总之，NF2基因敲除通过增加YAP表达，促进DCM中CF增殖、转分化及胶原分泌；线粒体自噬水平增加，减少坏损线粒体堆积，为CFs增殖及活化提供能量，导致DCM心肌纤维化的持续发生。