Characterization of the human papillomavirus E2 protein: evidence of trans-activation and trans-repression in cervical keratinocytes.

Bouvard, Véronique; Storey, Alan; Pim, David; Banks, Lawrence

doi:10.1002/j.1460-2075.1994.tb06880.x

Cited by 167 publications

(171 citation statements)

References 37 publications

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“…Our binding data suggest that the hE2 protein might positively and negatively regulate transcription of its own gene at low and high E2 concentrations, respectively. This hypothesis is consistent with the results of previous studies which have shown that although hE2 activates transcription from the P97 promoter, increased expression of the hE2 protein results in transcriptional repression (18). Similar concentration-dependent effects of HPV 8 E2 have been observed at the HPV 8 late gene promoter (30).…”

Section: Discussionsupporting

confidence: 93%

“…For example, the hE2 protein has been shown to activate transcription from the HPV 16 P97 promoter whereas, under exactly the same conditions, the bE2 protein has been shown to repress P97 promoter activity (18). Our results highlight a further difference between these proteins; in comparison to bE2, the hE2 protein recognizes an extended binding site.…”

Section: Discussionmentioning

confidence: 63%

“…Over-expression of the hE2 protein has been shown to repress the activity of some P97 promoter fragments linked to reporter genes (15, 16). However, in similar experiments over-expression of hE2 was found to activate transcription from other promoter derivatives (4,5,17,18). This confusion over the role of the hE2 protein is probably brought about by differences in the contribution of each of the four hE2-binding sites toward P97 promoter activity.…”

mentioning

confidence: 89%

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DNA Binding and Bending by the Human Papillomavirus Type 16 E2 Protein

Thain¹,

Webster

Emery³

et al. 1997

Journal of Biological Chemistry

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The human papillomavirus (HPV) 16 E2 protein (hE2) binds to four sites present upstream of the P97 promoter and regulates transcription of the viral E6 and E7 oncogenes. We have determined the relative binding constants for the interaction of the full-length hE2 protein with these sites. Our results show that hE2 binds tightly to site 4, less tightly to sites 1 and 2, and weakly to site 3. Similar results have previously been obtained using a C-terminal fragment of the hE2 protein suggesting that the C-terminal domain is the sole determinant of DNA binding affinity and specificity. Using circular permutation assays we show that binding of the hE2 protein induces the formation of a significant DNA bend and that the hE2-induced DNA bend angle is the same at both tight and weak hE2-binding sites. An alignment of the four hE2-binding sites from the HPV 16 genome suggests that this protein recognizes an extended binding site when compared with the bovine papillomavirus E2 protein. Here we show that the hE2 protein binds tightly to sites containing an A:T or a G:C base pair at position 7 of its binding site but weakly to sites containing either C:G or T:A at this position. Using site-directed mutagenesis we demonstrate that an arginine at position 304 of the hE2 protein is responsible for the recognition of specific base pairs at this position.The recognition of specific DNA sequences by transcription factors is often the first step in the regulation of gene expression. An understanding of how these proteins recognize their target sequences, and the effect that this has on DNA conformation, is central to the question of how genes are controlled. We are studying the human papillomavirus E2 protein, a sequence-specific DNA-binding protein involved in the regulation of viral gene expression and DNA replication. Papillomaviruses infect epithelial cells and induce the formation of benign hyperproliferative lesions or warts. Over 70 distinct types of human papillomavirus (HPV) 1 have been described. Some of these viral types produce lesions that have the potential to undergo malignant transformation. HPV 16 and HPV 18, for example, are thought to play a primary role in the development of cervical cancer (for a review, see Ref. 1). The products of the viral E6 and E7 genes form complexes with the cellular tumor suppressor proteins p53 and Rb, respectively. These interactions bring about a change in cell growth rate and promote cell immortalization (reviewed in Ref.2). In HPV 16, transcription of the E6 and E7 genes is under the control of a single promoter (P97) that lies immediately upstream of the E6 gene (3). The activity of the P97 promoter is regulated by a variety of cellular transcription factors and by the viral E2 protein (4 -6).Much early work concentrated on the bovine papillomavirus (BPV) E2 protein. The BPV E2 protein (bE2) binds as a dimer to 12 inverted repeats (consensus sequence 5Ј-ACCGN 4 CGGT-3Ј) present upstream of the BPV early genes and activates transcription (7,8). Binding of bE2 protein to DNA is coo...

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 63%

mentioning

confidence: 89%

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DNA Binding and Bending by the Human Papillomavirus Type 16 E2 Protein

Thain¹,

Webster

Emery³

et al. 1997

Journal of Biological Chemistry

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“…The E2 open reading frame (ORF) encodes at least two or three different proteins which all act as transcription factors and regulate viral transcription (Cripe et al 1987;Baker et al 1987;Bouvard et al 1994). The E2 proteins bind to the E1 and stimulate viral DNA …”

Section: E1 and E2 Proteinsmentioning

confidence: 99%

Human papillomavirus type 16 in head and neck carcinogenesis

2005

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“…This was left for 5 h prior to removal of the transfection solution disruption of the HPV-16 E2 gene in cervical tumours and the transcriptional repression of the URR detected in initial studies with HPV-16 E2, a model that emerged was that disruption of the E2 gene removes a major negative regulatory influence on the HPV-16 URR (for reviews see Ham et al, 1991 ;McBride et al, 1991). However, more recent studies have suggested that the major function of the E2 protein is as a transactivator of the HPV-16 URR (Bouvard et al, 1994 ;Ushikai et al, 1994), which does not provide an easy explanation for the role of the disruption of the E2 reading frame detected in most cervical tumours.…”

mentioning

confidence: 99%

Cytokeratin patterns of expression in human epithelial cell lines correlate with transcriptional activity of the human papillomavirus type 16 upstream regulatory region.

Tergaonkar

Mythily

Krishna

1997

Journal of General Virology

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A comparison of the CAT reporter activity of a plasmid which contains the 232 bp epithelial specific enhancer alone with that of plasmids which contain additional sequences from the human papillomavirus type 16 ( HPV-16) upstream regulatory region (URR) revealed two markedly different patterns, in an analysis of six human epithelial cell lines. In HeLa, C33A and SiHa, the CAT reporter activities of all the constructs were comparable. In contrast, in CaSki, HK2bE6-E7 and HaCaT we detected very low levels of CAT reporter activity using the constructs with the additional HPV-16 URR sequences. The ability of HPV-16 E2 to transactivate a construct with 2 E2 binding sites also differed markedly and showed the same pattern. Cytokeratin staining revealed a correlation between cytokeratin 10 and 14 expression and the transcriptional differences observed. We also found alterations in the activity of one of the constructs on altering the growth conditions of the HaCaT cell line.Human papillomavirus type 16 (HPV-16) genomes are present in a very large proportion of cervical cancers and the E6 and E7 oncogenes of the virus are believed to be the major transforming genes (for review see zur Hausen, 1996). The non-coding region of HPV-16 is usually referred to as the upstream regulatory region (URR) since it modulates the activity of the p97 promoter which controls transcription of the E6 and E7 oncogenes. In situ hybridization studies on clinical infections (Durst et al., 1992 ;Stoler et al., 1989) and virion generation efforts using raft culture systems have emphasized (Dollard et al., 1992) both the epithelial specificity and the tight link between the regulation of papillomavirus transcription and the differentiation of epithelial cells. In addition, during the progression to higher grade lesions and

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Characterization of the human papillomavirus E2 protein: evidence of trans-activation and trans-repression in cervical keratinocytes.

Cited by 167 publications

References 37 publications

DNA Binding and Bending by the Human Papillomavirus Type 16 E2 Protein

DNA Binding and Bending by the Human Papillomavirus Type 16 E2 Protein

Human papillomavirus type 16 in head and neck carcinogenesis

Cytokeratin patterns of expression in human epithelial cell lines correlate with transcriptional activity of the human papillomavirus type 16 upstream regulatory region.

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