ABSTRACT
Objective To investigate the possible mechanism that hepatocyte growth factor (HGF) inhibits renal tubular epithelial-mesenchymal transition (EMT),and to determine whether Smurf2 expression induced by TGF-β1 can be reversed by HGF in normal rat kidney epithelial cells (NRK-52E).Methods Using rat NRK-52E cell line as an in vitro system,NRK-52E cells were incubated with 5 μg/L TGF-β1 for 0-24 h.Part of cells were pretreated with 20 μg/L HGF for 30 min or not,then incubated with or without 5 μg/L TGF-β1 for 1 h or 48 h.The other cells were transfected with pFlag-Smurf2 or Smurf2 siRNA for 24 h,then treated with or without 20 μg/L HGF for 24 h.The expressions of Smurf2,SnoN,E-cadherin,alpha-smooth muscle actin (α-SMA) and fibronectin (FN) were detected by Western blotting and indirect immunofluorescence staining assays.Results Compared to normal control,TGF-β1 could rapidly induce Smurf2 protein expression in a short time (P＜0.01).Meanwhile,the expressions of FN and α-SMA were significantly induced,and the expression of E-cadherin was reduced in NRK-52E cells by TGF-β1.In contrast,in the NRK-52E cells pretreated with HGF,HGF could obviously inhibit Smurf2 expression induced by TGF-β1,and reversed the down-regulation of SnoN (P＜0.01) and E-cadherin (P＜0.05),the up-regulation of α-SMA (P＜0.01) and FN (P＜0.01) induced by TGF-β1.Moreover,overexpression of Smurf2 in NRK-52E cells could partly inhibit the up-regulation of SnoN protein by HGF,while down-regulation of Smurf2 could up-regulate the expression of SnoN induced by HGF.Conclusions HGF can abolish EMT induced by TGF-β1 in renal tubular epithelial cells through down-regulating Smurf2 expression and suppressing ubiquitin-proteasome dependent degradation of SnoN.