心脏Gli1+周细胞向肌成纤维细胞分化是促进心肌纤维化的重要新机制，但其影响因素和调控机制尚不明确。本课题在揭示微血管内皮细胞是心脏补体C1q/肿瘤坏死因子相关蛋白(CTRP)15 主要来源的基础上，利用内皮细胞特异性过表达CTRP15的转基因小鼠，观察CTRP15对心肌纤维化进程的影响；利用细胞谱系示踪技术以及将稳定过表达或敲除CTRP15的微血管内皮细胞与Gli1+周细胞共培养，明确CTRP15在调控Gli1+周细胞向肌成纤维细胞分化中的作用。将Hedgehog(Hh)信号通路作为CTRP15的关键作用靶点，利用放射性配基结合试验、FRET、AlphaLISA、ChIP等技术，从配体、膜受体及转录因子水平深入揭示CTRP15对Hh信号通路的影响。本研究将揭示CTRP15是抑制心脏Gli1+周细胞向肌成纤维细胞分化和心肌纤维化的新内源性保护因子，为临床防治心肌纤维化提供新的靶点与思路。

Although the differentiation of cardiac Gli1+ pericytes into myofibroblasts is recently revealed as the predominant contributor to cardiac fibrosis, little is known about the factors and mechanisms that controll this process. Our preliminary data showed that complement C1q/tumor necrosis factor-related protein (CTRP) 15 originated mainly from cardiac microvascular endothelial cells. In this study, we will examine the development of cardiac fibrosis in the wild type mice and the transgenic mice with endothelial-specific overexpression of CTRP15 underwent transverse aortic constriction (TAC). This study will further reveal the effect of CTRP15 on the differentiation of cardiac Gli1+ pericytes into myofibroblasts in in vivo fate-tracing studies using the Gli1CreERt2; tdTomato mice. The direct action of CTRP15 on the differentiation of cardiac Gli1+ pericytes into myofibroblasts will be determined by the coculture of cardiac Gli1+ pericytes with human cardiac microvascular endothelial cells (HCMEC) in which CTRP15 is stably over-expressed or stably knocked-down. To clarify the key target of CTRP15 in regulating the myofibroblasts differentiation from cardiac Gli1+ pericytes, we will observe the effect of CTRP15 on hedgehog (Hh) signaling pathway in cardiac Gli1+ pericytes. The expression of Hh ligands, the activation of membrane receptors, and the transcription activity of Gli1 will be determined by using radioligand binding assay, fluorescence resonance energy transfer (FRET), AlphaLISA, and chromatin immunoprecipitation (ChIP). This study will identify CTRP15 as a novel endogenous cytokine protecting against the differentiation of cardiac Gli1+ pericytes into myofibroblasts and the pathogenesis of cardiac fibrosis. Our research also offers a new therapeutic strategy for preventing and treating cardiac fibrosis.