%0 Journal Article %A Carlotti, Franco %A Crawford, Lionel %T Trans-activation of the adenovirus E2 promoter by human papillomavirus type 16 E7 is mediated by retinoblastoma-dependent and -independent pathways %D 1993 %J Journal of General Virology, %V 74 %N 11 %P 2479-2486 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-74-11-2479 %I Microbiology Society, %X In common with the adenovirus E1A and simian virus 40 large T oncoproteins, the E7 protein of human papillomavirus (HPV) type 16 interacts with the retinoblastoma (Rb) tumour suppressor protein (pRb). The functional importance of this interaction for HPV-16 E7 protein was investigated by analysis of the trans-activating function of E7 at the adenovirus E2 promoter in a set of breast tumour cell lines. Trans-activation by HPV-16 E7 in two pRb-deficient cell lines demonstrated that pRb is not essential for E7-mediated trans-activation, but reconstitution of Rb expression indicated the existence of an Rb-mediated pathway of E7 trans-activation. This pathway results from suppression by E7 of a trans-repressing function encoded by the Rb gene. The E7 protein is shown to be capable of interacting in vivo with the Rb-related protein p107. Furthermore, analysis of a fusion construct between the amino terminus of Rb and the carboxy terminus of p107 suggests that, in common with pRb, the p107 protein trans-represses the adenovirus E2 early promoter. Therefore it is proposed that the pRb-independent pathway of E7 trans-activation is a consequence of the suppression of trans-repression by p107. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-74-11-2479