title: MAD2B promotes tubular epithelial-to-mesenchymal transition and renal tubulointerstitial fibrosis via Skp2.
abstract: 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.
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Tang
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Di
authors.initials: D
authors.lastname: Fan
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Chun-Tao
authors.initials: CT
authors.lastname: Lei
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Ye
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Gao
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Neurobiology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
authors.forename: Xian-Fang
authors.initials: XF
authors.lastname: Meng
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Su
authors.affiliation: Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China. drzhangchun@hust.edu.cn.
authors.forename: Chun
authors.identifier: 0000-0003-3565-8024
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000818:Animals; D015536:Down-Regulation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005355:Fibrosis; D017353:Gene Deletion; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D064246:Mad2 Proteins / Q000378:metabolism*; D008297:Male; D008810:Mice, Inbred C57BL; D051381:Rats; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D014517:Ureteral Obstruction / Q000378:metabolism / Q000473:pathology
chemical_list: C120552:MAD2L2 protein, human; D064246:Mad2 Proteins; C577699:Mad2l2 protein, mouse; D044786:S-Phase Kinase-Associated Proteins; D053773:Transforming Growth Factor beta1
keywords: MAD2B; Renal tubulointerstitial fibrosis; Skp2; Tubular epithelial-to-mesenchymal transition