Multiple interactions between cellular factors and the non-coding region of human papillomavirus type 16.

The interaction between cellular factors and the non-coding region (NCR) of human papillomavirus type 16 (HPV-16) has been studied using different approaches; DNase I hypersensitive sites (HSS) analysis of HPV-16 chromatin in SiHa cells, footprinting (FP) of the NCR in vitro with nuclear extracts from SiHa cells and band shift analysis of synthetic oligonucleotides corresponding to the HSS and footprint sites with nuclear extracts from a variety of cells. These analyses have shown that cellular DNA-binding factors (CDBFs) bind to at least 13 sites, FP-A to M, over approximately 500 bp in the 3' half of the NCR. FP-E to H overlap with the keratinocyte-dependent enhancer and most sites contain the consensus sequence ATGCCAAAT, which is similar to both the cytokeratin promoter element AARCCAAA and the ubiquitous CCAAT motif. FP-E appears to be the target for C/EBP and AP1 binding, but FP-F, G and H appear to bind novel specific cellular factors. The CDBF binding to FP-G has been tentatively identified as the same factor binding to the cytokeratin promoter element.