NMIIA/MG53 通路在 CKD 肾小管间质纤维化中的作用及机制研究

Renal tubular epithelial cell injury and the activation of tubulointerstitial fibroblasts are of vital importance during the onset and progression of renal fibrosis. Thus, exploration of the mechanisms mediating the renal tubular cell injury and the activation of tubulointerstitial fibroblasts will help to find effective target for the prevention and treatment of CKD. NMIIA，a motor protein involved in cell morphology, has been shown to interact with MG53 to regulate vesicle trafficking during cell membrane repair. Our previous studies showed that NMIIA and MG53 are both upregulated in mouse UUO model and fibroblast activation and renal tubular cell injury induced by TGF-β1. Silencing NMIIA or pharmacological inhibition of NMIIA significantly attenuated fibroblast activation. Overexpression of MG53 promoted tubular cell injury. Meantime, knockdown of NMIIA downregulated MG53, while silencing of MG53 did not alter the expression of NMIIA, indicating that MG53 is downstream of NMIIA. These preliminary data suggested that NMIIA/MG53 might play an important role in renal fibrosis. Further we observed that β-catenin protein was reduced in renal tubular cells when MG53 was silenced. Thus, our hypothesis is that under the stimulation of profibrogenic factors, NMIIA may regulate MG53 to activate profibrotic signaling of wnt/β-catenin to initiate and promote the fibrotic response. In this proposal, we will employ the human kidney samples and the models of animals, cells, and molecules to fully investigate the role of NMIIA/MG53/β-catenin pathway in mediating the renal tubulointerstitial fibrosis, which will provide new insights into the prevention and treatment of CKD.

肾小管上皮细胞（RTEC）损伤及肾间质成纤维细胞活化是启动肾纤维化的关键环节，对其发生机制进行深入研究有助于寻找新的干预靶点。NMIIA是一种细胞骨架蛋白，可协助MG53的膜转位而促进细胞膜的修复。但NMIIA/MG53在肾脏纤维化中尚无报道。预实验结果显示在UUO小鼠及TGFβ1处理的成纤维细胞及RTEC，NMIIA和MG53均显著上调；阻断NMIIA可抑制成纤维细胞活化，过表达MG53增加了细胞外基质水平；siRNA沉默NMIIA下调了MG53表达，提示NMIIA可能通过MG53介导了肾脏纤维化。进一步，敲低MG53可降低致纤维化分子β-catenin。因而推测：在促纤维化因素作用下，NMIIA通过上调MG53来激活wnt/β-catenin，启动肾纤维化。本项目将在整体、细胞及分子层面探讨NMIIA/MG53/β-catenin通路在肾间质纤维化中的作用，为防治CKD提供新视角。

慢性肾脏病(CKD)肾间质纤维化是CKD的重要病理特征，在CKD的进展中发挥了重要的作用，但是病理机制尚不十分清楚，临床上也缺乏有效的干预手段。本项目利用CKD患者肾脏组织样本、转基因小鼠、药物干预及分子手段，在体内及体外CKD模型系统研究了NMIIA在CKD肾纤维化中的作用与机制，阐明了： 1. 肾小管上皮细胞及肾间质成纤维细胞NMIIA在CKD肾间质纤维化中发挥了重要的病理作用；2. Aldh1a1作为NMIIA的下游作用分子介导了NMIIA的促肾间质纤维化作用；3. 靶向NMIIA的抑制剂Blebbistatin可以有效改善小鼠CKD肾间质纤维化； 4靶向NMIIA下游分子Aldh1a1的抑制剂NCT501可以有效改善小鼠CKD肾间质纤维化。本项目的实施与完成，不但发现了CKD肾间质纤维化的病理新机制，同时也为临床干预CKD提供了新的干预靶点及可能的靶点药物。