Mutational analysis of cis elements involved in E2 modulation of human papillomavirus type 16 P97 and type 18 P105 promoters

Romanczuk, H; Thierry, Françoise; Howley, Peter

doi:10.1128/jvi.64.6.2849-2859.1990

Cited by 244 publications

(134 citation statements)

References 55 publications

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“…In the case of episomal persistence, the E l and E2 proteins are essential to guarantee viral DNA replication (Lambert, 1991;McBride et al, 1991). From our sequence results no mutations occurred in the 3 promoter proximal E2-binding sites, which have been shown to be crucial for E2-mediated repression of transcription (Romanczuk et al, 1990). This suggests that inactivation of the EZdependent regulatory circuit is not a usual event in the case of extrachromosomal HPV-16 DNA.…”

Section: Discussionmentioning

confidence: 80%

Prevalence of deletions of YY1‐binding sites in episomal HPV 16 DNA from cervical cancers

Dong¹,

Stubenrauch²,

Beyer-Finkler³

et al. 1994

Intl Journal of Cancer

131

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Expression of the oncogenes E6 and E7 of human papillomavirus 16 (HPV 16) appears enhanced in pre-malignant and malignant genital tumors. We recently identified a transcriptional silencer upstream of the oncogene promoter P97, comprising 4 binding sites for the cellular YY1 protein. The analysis of the long transcriptional control regions (LCR) of episomal HPV 16 DNAs from primary tumors and lymph-node metastases of 6 patients with cervical cancer revealed deletions and point mutations of YY1 binding sites in 4 cases. To test for the activity of the P97 promoter, the mutated LCRs were cloned in a luciferase reporter gene vector. A point mutation in YY1-recognition site 4, which prevents DNA-protein interaction, did not affect promoter activity, probably due to compensation by the overlapping YY1-binding site 3. However, 5.5- to 6.5-fold increased luciferase expression was obtained under the control of 3 shortened LCRs lacking 2 to 4 YY1-binding sites. A point mutation in YY1-recognition site 2, which was previously shown to stimulate P97 3.5-fold, could be detected in the HPV 16 LCRs from both primary tumor and metastasis, indicating that the mutation is a stable characteristic of HPV 16 DNA associated with the individual cancer. These findings suggest that deletions or mutations of YY1-binding sites play a significant role in over-expression of viral oncogenes and tumor progression.

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Section: Discussionmentioning

confidence: 80%

Prevalence of deletions of YY1‐binding sites in episomal HPV 16 DNA from cervical cancers

Dong¹,

Stubenrauch²,

Beyer-Finkler³

et al. 1994

Intl Journal of Cancer

131

127

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“…Oligonucleotide sequence coordinates from OL11, 12, 13, 14 and 15 are depicted in Figure lB cover the HPV-18 promoter sequence from position -82 to position -216. The sequence between positions -1 and -81, which contains two TATA boxes (at positions -76 and -29) and two recognition sites for E2, a major viral regulatory protein Bernard et al, 1989;Romanczuk et al, 1990), was not analysed. The E2 regulatory elements were not included in the present study because HeLa cells contain no E2 protein since the gene is deleted (Schneider-Gadicke and Schwarz, 1986).…”

Section: Resultsmentioning

confidence: 99%

Identification of a negative regulatory domain in the human papillomavirus type 18 promoter: interaction with the transcriptional repressor YY1.

et al. 1992

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The human papillomavirus type 18 (HPV-18) promoter contains a TPA responsive element TRE) which confers TPA responsiveness on a heterologous promoter. In the context of the HPV-18 promoter, however, this AP-1 site is inactive. We have identified a negative regulatory domain in the HPV-18 promoter which represses the constitutive and TPA-induced AP-1 activity. This negative regulatory sequence has been mapped to 44 nucleotides (OL13). We identified this element as a transcriptional silencer based on its ability to interfere with transcriptional initiation. This HPV-18 silencer domain was narrowed down further to 23 nucleotides, the OL13B element, which bears similarity to three other silencer sequences, present in the mouse N-ras gene upstream regulatory region, the mouse albumin gene enhancer and the adeno-associated virus P5 promoter. The transcriptional repressor protein YY1, which negatively regulates the P5 promoter, binds to the HPV-18 silencer with high affmiity. Mutation of the YY1 binding site leads to an enhanced activity of the HPV-18 promoter, strongly suggesting that YY1 plays an important role in controlling HPV-18 early gene expression.

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“…1) that share a consensus DNA sequence 5 0 -ACCG(N) 4 CGGT-3 0 . 10 The E2BS1 recruits E2 even at low concentration with high affinity. Binding of E2 to the E2BS1 triggers transcriptional activation of the early promoter, 11,12 leading to enhanced production of early viral proteins, including E2 itself and the oncogenic proteins E6 and E7.…”

mentioning

confidence: 99%

Differential methylation of E2 binding sites in episomal and integrated HPV 16 genomes in preinvasive and invasive cervical lesions

Chaiwongkot

Vinokurova

Pientong

et al. 2012

Intl Journal of Cancer

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Enhanced expression of the HPV 16 E6-E7 oncogenes may trigger neoplastic transformation of the squamous epithelial cells at the uterine cervix. The HPV E2 protein is a key transcriptional regulator of the E6-E7 genes. It binds to four E2 binding sites (E2BSs 1-4) in the viral upstream regulatory region (URR). Modification of E2 functions, for example, by methylation of E2BSs is hypothesized to trigger enhanced expression of the viral E6-E7 oncogenes. In the majority of HPV-transformed premalignant lesions and about half of cervical carcinomas HPV genomes persist in an extra-chromosomal, episomal state, whereas they are integrated into host cells chromosomes in the remaining lesions. Here we compared the methylation profile of E2BSs 1-4 of the HPV 16 URR in a series of 18 HPV16-positive premalignant lesions and 33 invasive cervical cancers. CpGs within the E2BSs 1, 3, and 4 were higher methylated in all lesions with only episomal HPV16 genomes compared with lesions displaying single integrated copies. Samples with multiple HPV16 integrated copies displayed high methylation levels for all CpGs suggesting that the majority of multiple copies were silenced by extensive methylation. These data support the hypothesis that differential methylation of the E2BSs 1, 3 and 4 is related to the activation of viral oncogene expression in cervical lesions as long as the viral genome remains in the episomal state. Once the virus becomes integrated into host cell chromosomes these methylation patterns may be substantially altered due to complex epigenetic changes of integrated HPV genomes.Persistent infections with high-risk human papillomaviruses (HR-HPVs) are the primary cause of cancer at various sites of the anogenital tract, including the cervix, vulva, vagina, penis and anus, as well as a subset of head and neck cancers. 1 The predominant HR-HPV type in cervical cancers is HPV16, accounting alone for about 50% of all cervical cancers. 2 It is commonly accepted that HPVs infect the basal cells of the squamous epithelium. Oncogenic human papillomaviruses encode two well-characterized oncoproteins, E6 and E7 that are under tight transcriptional control in early permissive, but not yet transformed genital HPV-infections. The enhanced expression of these oncogenes in basal and parabasal squamous epithelial cells of the infected epithelium is the cause of neoplastic transformation of the infected cells. 3,4 The main transforming properties of the E6 and E7 oncoproteins are related to their ability to inactivate the p53 and retinoblastoma (pRB) tumor suppressor proteins, respectively. 4-7 E7 overexpression in HPV-infected cells is accompanied by substantial overexpression of the cyclin-dependent kinase inhibitor p16 INK4a . p16 INK4a overexpression is therefore used as surrogate biomarker for HPV-transformed epithelial cells. 8 Expression of the E6 and E7 genes is regulated by the upstream regulatory region (URR). The HPV 16 URR contains sequences that regulate transcription and replication of the viral genome to which both cell...

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Mutational analysis of cis elements involved in E2 modulation of human papillomavirus type 16 P97 and type 18 P105 promoters

Cited by 244 publications

References 55 publications

Prevalence of deletions of YY1‐binding sites in episomal HPV 16 DNA from cervical cancers

Prevalence of deletions of YY1‐binding sites in episomal HPV 16 DNA from cervical cancers

Identification of a negative regulatory domain in the human papillomavirus type 18 promoter: interaction with the transcriptional repressor YY1.

Differential methylation of E2 binding sites in episomal and integrated HPV 16 genomes in preinvasive and invasive cervical lesions

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