Objective To study the effect of DNA methyltransferase 1(DNMT1)on sm-like protein-4(LSM4)in hepatocyte apoptosis in mice induced with Hcy.Methods 12 ApoE-/-mice were divided into two groups:normal diet(ND,n=6)and high methionine diet(HMD,n=6)groups.Normal hepatocytes of NCTC1469 were divided into a normal group(control,0 μL/L Hcy),Hcy intervention group(Hcy,100 μL/L Hcy),NC siRNA-transfected control group(si-NC group,0 μmol/L Hcy),LSM4 siRNA-transfected group(si-LSM4 group,0 μmol/L Hcy),DNMT1 siRNA-transfected group(si-DNMT1 group,0 μmol/L Hcy),NC siRNA-transfected Hcy intervention group(Hcy+si-NC group,100 μmol/L Hcy),LSM4 siRNA-transfected Hcy intervention group(Hcy+si-LSM4 group,100 μmol/L Hcy),and DNMT1 siRNA-transfected Hcy intervention group(Hcy+si-DNMT1 group,100 μmol/L Hcy).Analysis of the expression of LSM4 in various tissues was conducted using the NCBI database.Quantitative real-time PCR(qRT-PCR)and Western blot were used to detect differences in LSM4 protein expression in mouse tissues(HMD and ND)and hepatocytes(control and Hcy).Western blot was used to detect the expression of Bcl2-associated X(Bax)and B-cell lymphoma-2(Bcl-2).The cell apoptosis rate in the Control,Hcy,Hcy+si-NC,and Hcy+si-LSM4 groups were detected by flow cytometry.MethPrimer online software was used to analyze the CpG islands of LSM4 promoter region.The expression of LSM4 in the Hcy+si-DNMT1 group was detected by qRT-PCR and Western blot.Results The expression of LSM4 in HMD,Hcy group was higher than that in the ND and Control group(P＜0.05).Bax protein expression was significantly higher,but Bcl-2 was significantly lower in Hcy group compared with those of the Control group(P＜0.05).The expression of Bax protein was significantly lower,but the level of Bcl-2 was significantly higher in the Hcy+si-LSM4 group compared with those in the Hcy+si-NC group(P＜0.05).The cell apoptosis rate in the Hcy group was higher than that in the Control group(P＜0.05),while the apoptosis rate in the Hcy+si-LSM4 group was lower than that in the Hcy+si-NC group(P＜0.05).MethPrimer database analysis showed that the promoter region of LSM4 was GC-rich,and there was one CpG island.Compared with the Hcy+si-NC group,the Hcy+si-DNMT1 group's expression of LSM4 protein was increased(P＜0.05).Conclusions DNMT1 regulates LSM4 hypomethylation to increase its expression,thereby promoting Hcy-induced apoptosis of mouse hepatocytes.

Objective To study the effect of DNA methyltransferase 1(DNMT1)on sm-like protein-4(LSM4)in hepatocyte apoptosis in mice induced with Hcy.Methods 12 ApoE-/-mice were divided into two groups:normal diet(ND,n=6)and high methionine diet(HMD,n=6)groups.Normal hepatocytes of NCTC1469 were divided into a normal group(control,0 μL/L Hcy),Hcy intervention group(Hcy,100 μL/L Hcy),NC siRNA-transfected control group(si-NC group,0 μmol/L Hcy),LSM4 siRNA-transfected group(si-LSM4 group,0 μmol/L Hcy),DNMT1 siRNA-transfected group(si-DNMT1 group,0 μmol/L Hcy),NC siRNA-transfected Hcy intervention group(Hcy+si-NC group,100 μmol/L Hcy),LSM4 siRNA-transfected Hcy intervention group(Hcy+si-LSM4 group,100 μmol/L Hcy),and DNMT1 siRNA-transfected Hcy intervention group(Hcy+si-DNMT1 group,100 μmol/L Hcy).Analysis of the expression of LSM4 in various tissues was conducted using the NCBI database.Quantitative real-time PCR(qRT-PCR)and Western blot were used to detect differences in LSM4 protein expression in mouse tissues(HMD and ND)and hepatocytes(control and Hcy).Western blot was used to detect the expression of Bcl2-associated X(Bax)and B-cell lymphoma-2(Bcl-2).The cell apoptosis rate in the Control,Hcy,Hcy+si-NC,and Hcy+si-LSM4 groups were detected by flow cytometry.MethPrimer online software was used to analyze the CpG islands of LSM4 promoter region.The expression of LSM4 in the Hcy+si-DNMT1 group was detected by qRT-PCR and Western blot.Results The expression of LSM4 in HMD,Hcy group was higher than that in the ND and Control group(P＜0.05).Bax protein expression was significantly higher,but Bcl-2 was significantly lower in Hcy group compared with those of the Control group(P＜0.05).The expression of Bax protein was significantly lower,but the level of Bcl-2 was significantly higher in the Hcy+si-LSM4 group compared with those in the Hcy+si-NC group(P＜0.05).The cell apoptosis rate in the Hcy group was higher than that in the Control group(P＜0.05),while the apoptosis rate in the Hcy+si-LSM4 group was lower than that in the Hcy+si-NC group(P＜0.05).MethPrimer database analysis showed that the promoter region of LSM4 was GC-rich,and there was one CpG island.Compared with the Hcy+si-NC group,the Hcy+si-DNMT1 group's expression of LSM4 protein was increased(P＜0.05).Conclusions DNMT1 regulates LSM4 hypomethylation to increase its expression,thereby promoting Hcy-induced apoptosis of mouse hepatocytes.