ABSTRACT
Objective To investigate the effects of peptide-binding domain (PBD) of heat shock protein (HSP) 72 on epithelial to mesenchymal transition (EMT) in rat renal tubular epithelial cells.Methods The expressions of wild-type HSP72,mutant of HSP72 lacking peptide binding domain (HSP72-△PBD) and HSP72-PBD were induced by plasmid transfection.NRK-52E ceils were stimulated by TGF-β1 for 48 h.The expressions of α-smooth muscle actin (α-SMA),E-cadherin,HSP72 and Smad3/p-Smad3 were detected by Western blot and immunofluorescence.Results After NRK-52E cells were stimulated by TGF-β 1 (10 μg/L) for 48 h,the expression of α-SMA was increased and the protein level of E-cadherin was decreased.Western blotting and immunofluorescence showed that over-expression of both HSP72 and PBD inhibited TGF-β1-induced up-regulation of protein α-SMA expression,down-regulation of protein E-cadherin.However,overexpression of HSP72-△PBD did not change the protein level of E-cadherin and α-SMA.In addition,over-expression of HSP72 and PBD significantly inhibited the phosphorylation of Smad3.Conclusion Inhibition of Smad3 activation and EMT by HSP72 is associated with the function of PBD.