Tang Hui, Fan Di, Lei Chun-Tao, Ye Chen, Gao Pan, Chen Shan, Meng Xian-Fang, Su Hua, Zhang Chun
Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
J Mol Med (Berl). 2016 Nov;94(11):1297-1307. doi: 10.1007/s00109-016-1448-6. Epub 2016 Aug 3.
The mitotic arrest deficient protein MAD2B is a well-defined anaphase-promoting complex/cyclosome (APC/C) inhibitor and a small subunit of DNA polymerase zeta. It is critical for mitotic control and DNA repair. However, the pathological role of MAD2B in kidney diseases has not been fully elucidated. In the present study, we aim to explore the role of MAD2B in the pathogenesis of renal tubulointerstitial fibrosis (TIF) and the underlying mechanism. By immunofluorescence and immunohistochemistry, we found an obvious MAD2B enhancement in tubular area of TIF patients and unilateral ureteral obstruction (UUO) mice. In vitro, transforming growth factor-β1 (TGF-β1) induced a time-dependent MAD2B accumulation prior to tubular epithelial-to-mesenchymal transition (EMT) in a rat proximal tubular epithelial cell line, NRK-52E. Knocking down MAD2B using siRNA dramatically inhibited TGF-β1-induced tubular EMT process and subsequent extracellular matrix (ECM) production. We also found that Skp2, a confirmed APC/C-CDH1 substrate and E-cadherin destroyer, was increased in TGF-β1-treated proximal tubular epithelial cells, which could be blocked by MAD2B depletion. In addition, Skp2 expression was also found to be increased in the renal tubular area of UUO mice. Locally knocking down MAD2B expression in the renal cortex using lentiviral transfection inhibited Skp2 expression, tubular EMT, and subsequent ECM accumulation. Taken together, our data suggests a pro-fibrotic role of MAD2B in the pathogenesis of tubular EMT and TIF by inducing Skp2 expression. MAD2B might be a potential target of promising interventions for renal TIF.
Renal fibrosis activates MAD2B expression in renal tubules of human and mouse. TGF-β1 contributes to MAD2B enhancement in rat tubular epithelial cells. MAD2B depletion alleviates renal tubulointerstitial fibrosis in vivo and in vitro. MAD2B promotes EMT transition in rat tubular epithelial cells by inducing Skp2.
有丝分裂阻滞缺陷蛋白MAD2B是一种明确的后期促进复合物/细胞周期体（APC/C）抑制剂，也是DNA聚合酶ζ的一个小亚基。它对有丝分裂控制和DNA修复至关重要。然而，MAD2B在肾脏疾病中的病理作用尚未完全阐明。在本研究中，我们旨在探讨MAD2B在肾小管间质纤维化（TIF）发病机制中的作用及其潜在机制。通过免疫荧光和免疫组织化学，我们发现TIF患者肾小管区域和单侧输尿管梗阻（UUO）小鼠中MAD2B明显增强。在体外，转化生长因子-β1（TGF-β1）在大鼠近端肾小管上皮细胞系NRK-52E中，在肾小管上皮细胞向间充质细胞转化（EMT）之前诱导了时间依赖性的MAD2B积累。使用小干扰RNA敲低MAD2B显著抑制了TGF-β1诱导的肾小管EMT过程及随后的细胞外基质（ECM）产生。我们还发现，Skp2是一种已证实的APC/C-CDH1底物和E-钙黏蛋白破坏因子，在TGF-β1处理的近端肾小管上皮细胞中增加，而MAD2B的缺失可阻断这种增加。此外，在UUO小鼠的肾小管区域也发现Skp2表达增加。使用慢病毒转染在肾皮质局部敲低MAD2B表达可抑制Skp2表达、肾小管EMT及随后的ECM积累。综上所述，我们的数据表明MAD2B通过诱导Skp2表达在肾小管EMT和TIF发病机制中起促纤维化作用。MAD2B可能是肾TIF有前景干预措施的潜在靶点。
肾纤维化激活人和小鼠肾小管中MAD2B的表达。TGF-β1导致大鼠肾小管上皮细胞中MAD2B增强。MAD2B缺失在体内和体外减轻肾小管间质纤维化。MAD2B通过诱导Skp2促进大鼠肾小管上皮细胞的EMT转化。
