The Research Of Ubiquitin Hydrolase 22 On The Expression Of Collagen I Induced By Homocysteine

Objective: Hyperhomocysteinemia(Hyperhomocystinemia,HHCY)is associated with liver diseases such as hepatic fibrosis and fatty liver;however,the underlying mechanism is still largely unknown.The current study aimed to explore the signaling pathway involved in HHcy-induced hepaticfibrosis and the Effects of silencing USP22(ubiquitin carboxyl — terminal hydrolase 22,USP22)gene on proliferation and activation of human hepatic stellate cells.Methods: 1.18 mice were randomly divided into 3 groups: Normal control group(fed with national standard diet),2% high methionine diet fed for 1 weeks,and 2% high methionine diet fed for 2 weeks;2.The content of Hcy in the plasma of mice,the HE and Massion staining in liver tissue were detected,the expression of collagen I and USP22 in liver tissue were detected by Western blot,and the expression of collagen I and USP22 were also detected by immunohistochemistry;3.In vitro,HSC-LX2 cells were stimulated with different doses of homocysteine(Hcy)(0,6?mol/L,12?mol/L,24?mol/L,48?mol/L)and different times(0h,12 h,24h,48 h,72h).4.Western blot was used to detect the expression of collagen I and USP22 in human hepatic stellate cells stimulated by different doses and different concentrations of Hcy.5.Hepatic stellate cells were divided into 4 groups:The normal control group(human hepatic stellate cells not treated),Hcy stimulation group(human hepatic stellate cells under the stimulation by Hcy for a certain concentration and a certain period of time),siRNA group(siRNA USP22 silencing human hepatic stellate cells under the stimulation by Hcy),siNC group(siRNA NC silencing human hepatic stellate cells under the stimulation by Hcy);6.The expression of collagen I,USP22,P53,P27,P21,CyclinB1 protein in each group was detected by Western blot.Results: Compared to a chow diet,High-methionine diet(HMD)caused a significant increase of plasma Hcy concentration and an increase of USP22 expression in the liver of C57BL/6 mice than mice received chow diet.In cultured HSC-LX2,Hcy treatment induced protein levels of USP22 dose-dependently and time-dependently.Furthermore,we found that knockdown of USP22 induce the apoptosis of activated human hepatic stellate cells,leading to cell cycle arrest in G2 phase.Conclusions: 1.Hyperhomocysteinemia can be fed by a 2% high methionine diet;2.homocysteine can induce the expression of collagen I and induce the formation of fibrosis,which may be related to the high expression of USP22.Our results demonstrated that USP22 plays an important role in hyperhomocysteinemia induced liver fibrosis.