文档库

最新最全的文档下载
当前位置:文档库 > ndt.gfq619

ndt.gfq619

Nephrol Dial Transplant (2010)1of 8

doi:10.1093/ndt/gfq619

Original

ndt.gfq619

Article

Role of Sema4C in TGF-β1-induced mitogen-activated protein kinase activation and epithelial –mesenchymal transition in renal tubular epithelial cells

Rui Zeng 1,*

,Min Han 1,*,Yun Luo 1,Caixia Li 1

,Guangchang Pei 1,Wenhui Liao 2,Shoujun Bai 1,

Shuwang Ge 1,XiaoCheng Liu 1and Gang Xu 11Division of Nephrology,Department of Internal Medicine and 2Department of Geriatrics,Tongji Hospital,Tongji Medical College,Huazhong University of Science and Technology,Wuhan,Hubei,People ’s Republic of China

Correspondence and offprint requests to :Gang Xu;E-mail:xugang@http://www.wendangku.net/doc/7152288a680203d8ce2f24bd.html *These authors contributed equally to this work.

Abstract Background.The p38mitogen-activated protein kinase

(p38MAPK)is an important intracellular signal trans-

duction pathway involved in TGF-β1-induced epithelial –mesenchymal transition (EMT).Sema4C,a member of the semaphorin family,was found to be essential for the ac-tivation of p38MAPK.However,the role of Sema4C in promoting TGF-β1-induced EMT is unclear.Methods.Renal fibrosis was induced by 5/6subtotal neph-rectomy rat model.In vitro ,Sema4C was induced in human proximal tubular epithelial cells (HKC)by treatment with TGF-β1,or was inhibited by siRNA or was over-expressed by Sema4C transfection.The selective p38MAPK inhibi-tor,SB203580,was administered to inhibit the p38path-way.The expression of Sema4C,the markers of EMT,p38phosphorylation and fibronectin secretion were mea-sured by western blotting,immunohistochemistry,immuno-cytochemistry or enzyme-linked immunosorbent assay.Results.The expression of Sema4C increased in HKC cells that were treated with TGF-β1.Knockdown of Se-ma4C potently inhibited phosphorylation of p38MAPK and reversed TGF-β1-induced EMT.Over-expression of Sema4C via Sema4C transfection elicited p38MAPK phosphorylation and promoted EMT.The effects of Se-ma4C during EMT were blocked by a p38-specific in-hibitor.In vivo ,the expression of Sema4C increased in the tubular epithelia of 5/6-nephrectomized rats and hu-man fibrotic renal tissue,and similar localization of phosphorylated p38and Sema4C was demonstrated by immunohistochemistry on serial sections.Conclusions.Our findings suggest that Sema4C plays an important role in TGF-β1-induced EMT through activa-tion of p38MAPK in proximal tubular epithelial cells.Keywords:epithelial to mesenchymal transition;p38MAPK;Sema4C;TGF-β1Introduction

The progression of chronic kidney disease leads to wide-spread tissue fibrosis and irreversible loss of renal func-tion.Epithelial –mesenchymal transition (EMT)of tubular epithelial cells contributes significantly to the onset and pathogenesis of renal fibrosis [1–4].An extracellular stimulus usually initiates this process,which leads to the loss of junctional contacts,expression of mesenchymal markers,development of cell motility and production of extracellular matrix (ECM)[2,5].Of the many factors that trigger EMT,transforming growth factor-β1(TGF-β1)is the most important and well studied [6].TGF-β1mediates the EMT process via numerous intracellular signal trans-duction pathways,including the canonical Smad pathway,mitogen-activated protein kinases (MAPK),PI3K/Akt and small GTPases that control the activity or expression of factors related to EMT [7,8].

In recent years,significant evidence suggests that p38MAPK pathway is an important intracellular signal trans-duction pathway involved in TGF-β1-induced EMT in renal tubular epithelial cells [9,10].The activated p38MAPK could directly regulate the protein synthesis of α-smooth muscle cell actin (α-SMA)[10],indirectly activate Smad pathway [9],lead to excessive matrix deposition and finally induce the fibrotic process.However,the molecular details of how TGF-β1could potentially induce p38MAPK in renal tubular cells have not been elucidated yet.Sema4C,a member of the semaphorin family,has been shown to be essential for the activation of p38MAPK [11].The semaphorins are a large family of secreted or mem-brane-bound proteins that all have a conserved Sema do-

main,which is known to regulate tumor progression [12],

angiogenesis [13],nervous system development [14]and immune cell interactions [15].Our previous microarray

analysis of metastatic human cervical cancer tissue indi-

©The Author 2010.Published by Oxford University Press on behalf of the ERA-EDTA.All rights reserved.This is an Open Access article of

the Creative Commons Attribution License (http://www.wendangku.net/doc/7152288a680203d8ce2f24bd.html /licenses?by-nc/2.0/uk),which permits unrestricted non-commercial use distribution,and reproduction in any medium,provided the original work is properly cited.

NDT Advance Access published October 19, 2010 at Guangdong Medical College on January 20, http://www.wendangku.net/doc/7152288a680203d8ce2f24bd.html Downloaded from

ndt.gfq619

(共8页)

TOP相关主题