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The transcriptional transactivation function of wild‐type p53 is inhibited by SV40 large T‐antigen and by HPV‐16 E6 oncoprotein.
Author(s) -
Mietz J.A.,
Unger T.,
Huibregtse J.M.,
Howley P.M.
Publication year - 1992
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1992.tb05608.x
Subject(s) - transactivation , biology , plasmid , bovine papillomavirus , mutant , sv40 large t antigen , transfection , microbiology and biotechnology , reporter gene , wild type , transcription (linguistics) , gene , antigen , virology , transcription factor , gene expression , genetics , linguistics , philosophy , genome
The observed interaction between p53 and the oncoproteins encoded by several DNA tumor viruses suggests that these viruses mediate their transforming activities at least in part by altering the normal growth regulatory function of p53. In this study we examined the effect of viral oncoprotein expression on the transcriptional transactivation function of wild‐type p53 in human cells. Plasmids expressing human p53 were cotransfected with either SV40 large T‐antigen or human papillomavirus (HPV) type 16 E6 expression plasmids and assayed for transactivation function using a reporter gene driven by a p53‐responsive promoter containing multiple copies of the consensus p53 DNA binding motif, TGCCT. Both large T‐antigen and E6 were able to inhibit transactivation by wild‐type p53. Furthermore, SV40 T‐antigen mutants that are defective for p53 binding were not able to inhibit transactivation and HPV E6 proteins that were either mutant or derived from non‐oncogenic HPV types and unable to bind p53, had no effect on p53 transactivation. These results demonstrate the physiological relevance of the interaction of SV40 T‐antigen and HPV E6 oncoproteins with p53 in vivo and suggest that the transforming functions of these viral oncoproteins may be linked to their ability to inhibit p53‐mediated transcriptional activation.