THE E6 PROTEIN OF HUMAN PAPILLOMAVIRUS TYPE-16 FUNCTIONS AS A TRANSCRIPTIONAL REPRESSOR IN A MECHANISM INDEPENDENT OF THE TUMOR-SUPPRESSOR PROTEIN, P53

The E6 protein of human papillomavirus (HPV) type 16 displays a number of activities when transfected into cultured cells, including transcr iptional activation of several viral promoters and targeting of p53 fo r degradation. HPV 16E6 was found to function as a transcriptional rep ressor of the moloney murine leukemia virus long terminal repeat and t he cytomegalovirus immediate early promoter. Although the degree of tr anscriptional repression was low, a dose-dependent two- to threefold d ecrease in promoter;activity was consistently seen in cells expressing 16E6. HPV 16E6-dependent transcriptional repression was observed in C 33a cells, which express mutant p53, and in Saos-2 cells, which lack p 53. These results indicate that 16E6-dependent repression of promoter activity is unlikely to be mediated by p53. (C) 1994 Academic Press, I nc.