THE 5'-REGION OF THE HUMAN-PAPILLOMAVIRUS TYPE-31 UPSTREAM REGULATORYREGION ACTS AS AN ENHANCER WHICH AUGMENTS VIRAL EARLY EXPRESSION THROUGH THE ACTION OF YY1

Cis-elements which control human papillomavirus early gene expression have previously been localized to sequences in the upstream regulatory region (URR) which are proximal to the E6 open reading frame. These e lements include an enhancer element which functions preferentially in keratinocytes as well as promoter elements. The function of the remain ing approximate 500-bp region of the URR in regulating viral expressio n in the high risk papillomaviruses has been largely uncharacterized. In HPV 6, a negative regulator of early expression, or silencer, has b een identified in this 5' region of the URR. In this study, we have in vestigated the role of the 5' portion of the HPV 31 URR in regulating viral expression. Sequences in this region were found to exert a minim al negative effect on homologous or heterologous promoters. In contras t, a 128-bp sequence within this region was found to exhibit enhancer activity on heterologous and homologous promoters. This enhancer also augmented the activity of the previously identified minimum keratinocy te enhancer. The cellular factors, YY1 and TEF-1, were determined by D Nase I footprint analysis and electrophoretic mobility shift assays (E MSAs) to bind the 128-bp enhancer. The binding of YY1 to two of these sites was found to be important for enhancer activity. (C) 1997 Academ ic Press.