E2F1 Activates the Human p53 Promoter and Overcomes the Repressive Effect of Hepatitis B Viral X Protein (HBx) on the p53 Promoter

The functional effect of the interaction of E2F1 and hepatitis B virus X protein (HBx) on the promoter of human p53 gene was studied using chloramphenicol acetyl transferase (CAT) assay. E2F1 activated the p53 promoter through E2F1 binding site. As previously reported, HBx repressed the p53 promoter...

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Bibliographic Details
Published in:IUBMB life 2002-06, Vol.53 (6), p.309-317
Main Authors: Choi, Murim, Lee, Hyeon, Rho, Hyune Mo
Format: Article
Language:English
Subjects:
Base Sequence
Cell Cycle Proteins
Cell Line
DNA-Binding Proteins
E2F Transcription Factors
E2f1
E2F1 Transcription Factor
Gene Expression Regulation
Genes, p53
Hbx
HeLa Cells
Hepatitis B virus - pathogenicity
Humans
In Vitro Techniques
P53
Plasmids - genetics
Promoter
Promoter Regions, Genetic
Recombinant Proteins - metabolism
Trans-Activators - metabolism
Transcription
Transcription Factors - metabolism
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Summary:The functional effect of the interaction of E2F1 and hepatitis B virus X protein (HBx) on the promoter of human p53 gene was studied using chloramphenicol acetyl transferase (CAT) assay. E2F1 activated the p53 promoter through E2F1 binding site. As previously reported, HBx repressed the p53 promoter through E‐box. When E2F1 was cotransfected with HBx, E2F1 overcame the repressive effect of HBx on the p53 promoter through the E2F1 site. However, in the thymidine kinase ( tk ) heterologous promoter system with the E2F1 binding sites, cotransfection of E2F1 and HBx showed a strong synergistic activation. An in vitro interaction assay showed that E2F1 and HBx physically bind with each other. Analyses of the interaction domain with the GAL4 fusion protein showed that the pRb‐binding domain of E2F1 was necessary for the functional interaction of these two proteins. Taken together, these results imply the functional inhibitory action of E2F1 on the HBV life cycle and HBV‐mediated hepatocellular carcinogenesis (HCC). Therefore, the normal or enhanced function of E2F1 gene would be important in controlling the HBx function in HCC.
ISSN:1521-6543
1521-6551
DOI:10.1080/15216540213466