The interaction between Cdc42-Interacting protein 4 and β-catenin in renal tubular epithelial-mesenchymal transition / 中华肾脏病杂志

ABSTRACT

Objective To investigate the expression and distribution of Cdc42-interacting protein 4 (CIP4) in renal fibrotic tissue,and the interaction between CIP4 and β-catenin in transforming growth factor β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) model of HK-2 cell line.Methods In vivo,the model of renal fibrosis was induced by 5/6 subtotal nephrectomy in rat.Masson staining was used to evaluate the level of renal tissue fibrosis.The expression and distribution of CIP4 was detected by immunohistochemistry.In vitro,the EMT model of HK-2 cell line was induced by TGF-β1 (10 μg/L) for 72 h.Western blotting was used to observe the expression of E-cadherin,β-catenin,CIP4 and α-SMA.Colocalization and interaction of CIP4 and β-catenin were detected by immunofluorescence and immunoprecipitation respectively.Results Compared to sham group,CIP4 expression was increased in group of 5/6 subtotal nephrectomy,CIP4 was mainly distributed in basolateral side of renal tubular epithelia.In vitro,expressions of α-SMA and CIP4 were increased in HK-2 cells stimulated by TGF-β1 for 72 h (2.5and 1.8 folds,respectively) (all P＜0.05),expression of E-cadherin was decreased(P＜0.05).Partial colocalization between CIP4 and β-catenin was detected by immunofluorescence.In control group,CIP4 and β-catenin partially colocalized at the cell membrane.Mter the stimulation of TGF-β1,translocation to nucleus of CIP4 and β-catenin were increased,and partially colocalized in nucleus.The interaction between CIP4 and β-catenin was observed by immunoprecipitation in both control and TGF-β1 stimulated groups.Conclusions Expression of CIP4 in renal fibrotic tissue is increased,which is mainly distributed in basolateral side of renal tubular epithelia.CIP4 and βcatenin partially colocalize and interact with each other.CIP4 may play a role in EMT process through the interaction with β-catenin.