Studies Of Mechanisms Of Downregulation Of Histone Demethylase JMJD2D Promoting The Expression Of P21 In Hepatoma Cells

JMJD2D,also called KDM4D,is one of the histone demethylase JMJD2 super family members,whose main function is to remove H3K9me2 and H3K9me3 methyl moieties.Unlike other members of the family,it lacks the Tudor and PHD domain,with the molecular weight is only 60kDa,the half of other members JMJD2D was reported that plays an important role in colon cancer and prostate cancer,but its role in HCC progression remains unknown.In this study,we found that knockdown of JMJD2D significantly increased p21 expression at the mRNA level and the protein level in HepG2 and SK-Hep-1 cells.Luciferase reporter assay showed that when knockdown JMJD2D,the activity of p21 gene promoter significantly increased,suggested JMJD2D regulate p21 expression at the transcriptional level.Furthermore,we mutated the two binding sites of p53 in the p21 promoter,found that the regulation of p21 by JMJD2D is dependent on the proximal p53 binding site of p21 promoter.Next,we performed the ChIP experiment,which showed JMJD2D promoted p53 accumulate to p21 gene promoter in HepG2 cells.At last we used co-immunoprecipitation assay to find that C-terminal amino acids 313-523 of JMJD2D interacted with p53 DNA binding domain,which was affected the recognition and accumulation of p53 for p21 gene promoter,resulted in disrupting the p53-p21 pathway.In conclusion,our results show that JMJD2D binds to p53,which influences p53 trans-activate p21,leading to promote the development of HCC.All of these results suggest that JMJD2D could be potential target for the treatment of HCC,producing JMJD2D inhibitor may help us fight against HCC.