CTRP6调控心脏肌成纤维细胞转化—抑制心室间质重塑的新机制

The transformation of cardiac fibroblast to myofibroblast is principle for the interstitial remodeling after myocardial infarction (MI). Little is known about the effect of C1q TNF-related protein (CTRP)-6, a member of the CTRP family, on myofibroblast transformation and cardiac fibrosis. This study will investigate the alteration of CTRP6 expression in rats with cardiac fibrosis undergoing MI and observe the effect of CTRP6 over-expression in heart on myofibroblast transformation and interstitial fibrosis. In cultured adult rat cardiac fibroblast, we will explore the effect of CTRP6 on myofibroblast transformation and collagen production by use of methods including Real-time PCR, Western blot, immunofluorescent staining, and etc. The signal transduction mechanism involved in CTRP-6-modulated myofibroblast transformation will be revealed from receptor, intracellular protein kinase, and transcription factor levels by using pharmacological inhibitors, RNA interference, plasmid transfection, immunoprecipitation, and luciferase assay system. This study will clarify the key role of AMP-activated protein kinase (AMPK) and myocardin-related transcription factor A (MRTF-A), a serum response factor (SRF) co-activator, in controlling myofibroblast transformation. This study will provide a novle insight into the biological effect of CTRP6 and offer a new therapeutic target for preventing and treating myocardial interstitial remodeling.

心脏成纤维细胞向肌成纤维细胞转化是心脏间质重塑的关键节点，补体C1q/TNF相关蛋白家族成员CTRP6对其影响尚无报道。本课题拟在大鼠心肌梗死模型检测纤维化进程中CTRP6的变化；观察心脏局部过表达CTRP6对心脏肌成纤维细胞转化及间质纤维化的影响，在整体水平上明确CTRP6对间质重塑的作用。在离体培养的成年大鼠心脏成纤维细胞上，采用Real-time PCR、免疫印迹和免疫荧光等方法观察CTRP6对肌成纤维细胞转化和细胞外基质合成的影响；采用工具药、RNA干扰、质粒转染、免疫共沉淀以及荧光素酶报告基因检测等方法，从受体、胞内蛋白激酶、转录因子层面探讨CTRP6调控肌成纤维细胞转化的信号转导通路，明确AMPK以及血清反应因子的共转录激活因子MRTF-A在CTRP6抑制肌成纤维细胞转化中的关键作用和转录调控机制。这将为阐明CTRP6的生物学作用提供新见解，也为防治心脏间质重塑提供新思路。

心脏成纤维细胞向肌成纤维细胞转化是心脏损伤后间质重塑的关键节点，本项目以补体C1q/TNF相关蛋白CTRP6为重点，在大鼠心肌梗死模型上观察到梗死局部CTRP6表达下降，在心肌梗死大鼠的心前区注射CTRP6腺病毒，可显著改善心梗后心脏的舒缩功能，抑制心肌肥大，减轻心脏纤维化，从在体水平上证明CTRP6具有抑制心室重塑的作用。离体培养的大鼠心肌可合成和分泌CTRP6，并以旁分泌的形式作用在心脏成纤维细胞上，抑制TGF-β1诱导的肌成纤维细胞转化，减少胶原蛋白等细胞外基质的合成；敲低CTRP6可进一步增强TGF-β1诱导的心脏肌成纤维细胞转化及细胞外基质合成，明确了内源性CTRP6具有抑制抗心肌纤维化的作用。在信号通路上证实CTRP6通过激活AMPK/Akt抑制TGF-β1激活的RhoA/MRTF-A通路抑制肌成纤维细胞转化。此外，本项目还探讨了CTRP家族的另一成员CTRP3在心脏重塑中的作用，从整体与细胞水平证明CTRP3具有抑制心梗后心室重塑的作用，但CTRP3抗心脏纤维化的信号转导通路是通过激活AMPK，抑制Smad3磷酸化及其与p300的结合，从而抑制肌成纤维细胞转化。本项目的研究成果为阐明CTRP6和CTRP3作为内源性保护因子调控心脏纤维化的细胞和分子机制提供了新见解，为探寻防治心脏间质重塑的提供了新思路。