UCP1调控肾小管上皮细胞线粒体功能在肾小管间质纤维化中的作用及其机制

In recent years, the studies found that mitochondrial dysfunction is involved in the development and progression of renal tubular epithelial mesenchymal transition (EMT), the key feature of tubular interstitial fibrosis (TIF), but its mechanism has not been fully elucidated. UCP1 is a mitochondrial uncoupling protein that closely related to the regulation of mitochondrial function. Recently we found that the expression of UCP1 in the renal tubules of the unilateral ureteral obstruction (UUO) mice and in vitro TGF-β1-stimulated tubular epithelial cells is downregulated. Importantly, in vitro knockdown UCP1 could upregulate the production of reactive oxygen species (ROS) and activation of UCP1 could reverse TGF-β1-induced AMPK signaling pathway inhibition. These data prompt UCP1-AMPK plays a role in EMT and TIF by regulating tubular epithelial cells mitochondrial function. Based on these evidences, this project will utilize in vitro and in vivo models, and establish conditioned transgenic mice to explore the role and mechanism of UCP1-AMPK signaling pathway in mitochondria function regulation during EMT and TIF, and provide new scientific basis for prevention and control of the TIF.

肾小管上皮细胞间充质转变（EMT）是肾小管间质纤维化（TIF）的关键环节，研究表明，线粒体功能障碍与肾小管EMT的发生有关，但其机制尚未阐明。UCP1是一种线粒体解偶联蛋白，其表达水平与线粒体功能相关。我们的前期研究发现，UCP1在TIF小鼠肾小管和体外TGF-β1刺激的肾小管上皮细胞中表达下调；敲低UCP1可诱导肾小管活性氧（ROS）产生。另一方面，我们发现上调UCP1可逆转TGF-β1诱导的AMPK信号通路抑制。上述结果提示，UCP1-AMPK信号通路可能通过调控肾小管线粒体功能参与肾小管EMT与TIF进程。在此基础上，本项目拟采用体外细胞模型、肾小管上皮细胞特异性UCP1基因过表达的UUO小鼠模型为研究对象，通过表征和调控UCP1、AMPK的表达，探讨UCP1-AMPK信号通路在肾小管线粒体功能调控以及EMT和TIF进程中的作用及其分子机制，以期为TIF的防治提供新的科学依据。

肾小管间质纤维化（tubulointerstitial fibrosis，TIF）是慢性肾脏病（chronic kidney disease，CKD）进展至终末期肾脏病（end stage renal disease，ESRD）的共同病理改变和肾脏结构破坏的最终通路。肾小管上皮细胞间充质转变（epithelial mesenchymal transition，EMT）为肌成纤维细胞，导致肾间质细胞外基质（extracellular matrix，ECM）积聚是肾小管间质纤维化（tubular interstitial fibrosis，TIF）的特征病变。然而，肾小管上皮细胞发生EMT的机制尚不十分清楚。解偶联蛋白1（uncoupling protein 1，UCP1）是表达于线粒体内膜，与细胞能量代谢及氧化应激相关的关键分子，但其在肾脏纤维化疾病中的作用和具体机制尚无报道。本研究采用UUO小鼠动物模型和体外TGF-β1刺激的细胞模型为研究对象，通过表征和调控UCP1的表达，探讨UCP1在肾小管EMT和TIF中的关键作用及其机制。本项目主要研究结果如下：（1）在UUO模型小鼠和TGF-β1刺激的肾小管上皮细胞中，UCP1的表达下调；（2）上调UCP1表达可减轻UUO模型和TGF-β1刺激的肾小管上皮细胞EMT和细胞外基质积聚；（3）上调UCP1表达可降低UUO模型和TGF-β1刺激的肾小管上皮细胞氧化应激水平；（4）Sirt3是UCP1抗氧化应激缓解肾小管EMT和TIF的下游信号通路；（5）在顺铂诱导的急性肾损伤模型中，UCP1表达下降伴随脂质沉积；上调UCP1表达通过促进AMPK/ULK1/自噬信号通路减轻脂质沉积现象，延缓顺铂诱导的急性肾损伤进展。这些研究结果分别从细胞氧化应激和脂质沉积的角度，深化了对肾小管EMT 和急性肾损伤机制的认识，为TIF和急性肾损伤的防治提供新的理论依据和干预靶点。