Analysis Of Gene Promoter Methylation Related To Milk Production Traits In Dairy Cow

DNA methylation is one of the first discovered epigenetic modification ways,which plays animportant role in maintaining in individual development,genetic imprinting,cell function andoccurrence of diseases.DNA methylation refers to DNMTs catalyzes the S-adenosylmethionine asa methyl donor,which make cytosine convert to5-methyl cytosine.It involves regμlation of geneexpression by mediating gene silencing. In recent years,a potential role for epigenetic mechisms inthe regμlation of mammary function in dairy cow is emerging.Recent studies found that,the DNAmethylation regμlates expression of milk protein in different physiological and pathologicalconditions.Moreover,the management and rearing conditions of dairy cow may change epigeneticcharacters by some mechanisms,and transfer the characters to next generation.The paper compared the methylation characters of eight gene promoters (STAT5A、ELF5、AKT1、mTOR、RPS6KB1、EIF4EBP1、SREBP1、Cyclin D1) related to milk production traits inhigh quality,low quality and pregnancy mammary glands.First,we analyzed the eight genepromoters methylation status in mammary tissues.The results showed that5mCpG and5mCpN(A、T、C) patterns exist by BSP (Bisulfite Sequencing PCR)technology.Comeparing high qualitywith low quality tissues,the methylation level is lower in mTOR、RPS6KB1、EIF4EBP1、SREBP1、Cyclin D1promoters,the lactation phase is slightiy lower than the pregnancy.STAT5A and ELF5had no obvious change.Combinned with the qRT-PCR results,DNA may involes in regμlatingAKT1、mTOR、RPS6KB1、EIF4EBP1、SREBP1、Cyclin D1expression,except for STAT5A andELF5.In cell experiments,we focused on the effect of DNA methlation on regulating Cyclin D1expression by treatment of5-Aza,which is a methyltransferase inhibitor.The results suggestthat,the Cyclin D1promoter methylation level decreased relative to control group, mRNAexpression increased1.5times,and the west blotting results showed that Cyclin D1proteinincreased20%.