Transactivation-competent bovine papillomavirus E2 protein is specifically required for efficient repression of human papillomavirus oncogene expression and for acute growth inhibition of cervical carcinoma cell lines

Edward C. Goodwin, Lisa Kay Naeger, David E. Breiding, Elliot Androphy, Daniel DiMaio

Research output: Contribution to journalArticle

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Abstract

The papillomavirus E2 proteins can function as sequence-specific transactivators or transrepressors of transcription and as cofactors in viral DNA replication. We previously demonstrated that acute expression of the bovine papillomavirus type 1 (BPV1) E2 protein in HeLa and HT-3 cervical carcinoma cell lines greatly reduced cellular proliferation by imposing a specific G1/S phase growth arrest. In this report, we analyzed the effects of a panel of point mutations in the BPV1 E2 protein to identify the functional requirements for acute growth inhibition. Disruption of E2- specific transactivation by mutations within either the transactivation domain or the DNA binding domain severely impaired E2-mediated growth inhibition in HeLa and HT-3 cells, even though these mutants retain various other E2 activities. This result indicates that functional transactivation activity is required for acute E2-mediated growth inhibition. HeLa cells, which contain a wild-type p53 gene, and HT-3 cells, which contain a transactivation-defective p53 gene, exhibited similar responses to the E2 mutants, suggesting that identical functions of the E2 protein were required for growth arrest regardless of p53 status. Replacement of the E2 transactivation domain with that of the herpes simplex virus VP16 generated a chimeric transactivator that efficiently stimulated expression of an E2- responsive reporter plasmid yet was completely defective for growth inhibition, suggesting that an E2-specific transactivation function is required for growth arrest. Surprisingly, the transactivation-defective E2 mutants were also markedly defective in their ability to repress transcription of the native human papillomavirus type 18 (HPV18) E6/E7 oncogenes in HeLa cells and of the HPV18 promoter present in a transfected reporter plasmid. These mutants were also defective in their ability to increase p53 levels. Therefore, efficient repression of the HPV18 promoter in HeLa cells is not merely a consequence of the binding of an E2 protein to appropriately situated binding sites in the promoter.

Original languageEnglish (US)
Pages (from-to)3925-3934
Number of pages10
JournalJournal of Virology
Volume72
Issue number5
StatePublished - May 1998
Externally publishedYes

Fingerprint

Bovine papillomavirus
uterine cervical neoplasms
Papillomaviridae
oncogenes
transcriptional activation
Oncogenes
growth retardation
Transcriptional Activation
cell lines
Carcinoma
Cell Line
Human papillomavirus 18
Growth
Bovine papillomavirus 1
HeLa Cells
proteins
mutants
Trans-Activators
p53 Genes
promoter regions

ASJC Scopus subject areas

  • Immunology

Cite this

Transactivation-competent bovine papillomavirus E2 protein is specifically required for efficient repression of human papillomavirus oncogene expression and for acute growth inhibition of cervical carcinoma cell lines. / Goodwin, Edward C.; Naeger, Lisa Kay; Breiding, David E.; Androphy, Elliot; DiMaio, Daniel.

In: Journal of Virology, Vol. 72, No. 5, 05.1998, p. 3925-3934.

Research output: Contribution to journalArticle

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