Histone methyltransferase MLL1 accelerates the development of renal fibrosis via promoting the epithelial-mesenchymal transition of HK-2 cells / 中华肾脏病杂志

ABSTRACT

Objective To investigate the possible effects of histone methyltransferase MLL1 on renal interstitial fibrosis and epithelial-mesenchymal transition(EMT).Methods Forty-two male SD rats were randomly divided into normal group,sham operation group and unilateral ureteral occlusion(UUO)group,and then UUO group was further divided into group 1 d,1 week,2 week,3 week and 4 week after operation.The expression of MLL1,E-cadherin,α-SMA,Vimentin and Col3α1 in UUO rat kidney tissue as well as TGF-β1 stimulated HK-2 cells were detected by real-time PCR and Western blotting.siRNA-MLL1 plasmids was used to inhibit the expression of MLL1 and the protein levels of MLL1,α-SMA,Vimentin,E-cadherin,Col3α1 and H3K4me3 induced by TGF-β1 stimulation were detected by Western blotting.The level of H3K4me3 in promoter region of EMT related genes was observed by chromatin immunoprecipitation(CHIP).Results Compared with normal and sham operated groups,the loss of renal function in UUO group was more obvious with the obstruction time(P ＜ 0.05).The renal fibrosis was most obvious 1 week and 2 weeks after the rats underwent the UUO operation(all P ＜ 0.05),with the highest protein expressions of MLL1,E-cadherin,α-SMA,Vimentin and Col3α1(all P ＜ 0.05).Compared with the control group,3 ng/ml TGF-β1 induced the highest expression of MLL1 and the most obvious EMT in HK-2 cells(all P ＜ 0.05).Moreover,the EMT and the high level of H3K4me3 in HK-2 triggered by TGF-β1 were all inhibited by siRNA-MLL1 plasmids transfection(all P ＜ 0.05).Conclusions MLL1 can enhance the occurrence of EMT induced by TGF-β1 in HK-2 cells by increasing the level of H3K4me3 in the promoter region of α-SMA and Vimentin.