成纤维细胞活化增殖是肾脏纤维化发生发展的关键事件。我们新近发现慢性肾脏病患者肾组织成纤维细胞的线粒体呈分裂样改变，其程度与肾小球滤过率呈负相关；抑制小鼠慢性肾病模型Drp1介导的线粒体分裂可延缓肾脏纤维化；下调成纤维细胞株Drp1表达可降低TGF-β1诱导的H3K27乙酰化和α-SMA蛋白水平；乙酰化H3K27可与α-SMA基因启动子结合。提示线粒体分裂可调控成纤维细胞活化和肾脏纤维化，但其机制不清。本项目拟利用小鼠慢性肾病模型，阐明成纤维细胞线粒体分裂、活化增殖与纤维化的关系；应用Drp1特异性抑制剂、上调/沉默/变异线粒体Drp1水平/活性，探讨线粒体分裂直接调控成纤维细胞活化增殖的作用，研究抑制Drp1介导的线粒体分裂靶向阻止H3K27乙酰化调控细胞活化的机制。本项目有助于揭示成纤维细胞线粒体分裂促进肾脏纤维化的作用和机制，为探索和开发线粒体靶向分子防治肾脏纤维化提供可靠的实验依据。

Activation and proliferation of interstitial fibroblasts is the predominant cellular event indicating the development and progression of renal fibrosis. Our recent preliminary data showed that mitochondrial fragmentation in kidney of patient with chronic kidney disease negatively correlated with the estimated glomerular filtration rate. Inhibition of mitochondrial fission attenuated renal fibrosis in unilateral ureteral obstruction mice. Knockdown of dynamic related protein 1 (Drp1) by siRNA blocked TGF-β1-induced the expression levels of H3K27 acetylation (H3K27ac) and α-SMA in NRK-49F cells. Moreover, TGF-β1 treatment resulted in the increased H3K27ac in the promoter of α-SMA gene by chromatin immunoprecipitation. Our findings suggest that mitochondria fission regulates fibroblast activation and renal fibrosis. However, the mechanism(s) were unclear. In this proposal, mice models of chronic kidney nephropathy were used to further study the relationship among mitochondrial fission, activation and proliferation, and renal fibrosis. The direct effects of mitochondrial fission on activation and proliferation of fibroblasts were investigated by upregulating/downregulating/mutation Drp1 expression in NRK-49F cells. We also explore the mechanisms that suppression of Drp1-mediated mitochondrial fission inhibits acetylation of H3K27 and its related targets of gene. Our study will provide significant insight into the mechanism by which mitochondrial fission promotes renal fibrosis. Manipulation of mitochondrial fission might be a novel approach for the prevention and treatment of renal fibrosis.