Papillomaviruses induce persistent epithelial lesions, known as papillomas. Genital papillomavirus infection is widespread and associated with the development of cervical cancer. The viral E2 proteins regulate viral transcription, replication and episomal genome maintenance.
Our aim i s to elucidate the mechanisms by which the E2 proteins control the viral life cycle. We have shown that papillomavirus genomes and the E2 transactivator protein interact with cellular mitotic chromosomes in dividing cells. This ensures that viral genomes are properly segregated to daughter cells and are retained within the nucleus. The E2 transactivation domain of E2 interacts with the host chromosomes and so we have generated mutations on potential interaction surfaces of this domain and determined which abrogate the ability of E2 to interact with chromosomes. We have also identified regions of E2 important for replication and transcriptional repression. We have shown that E2 cannot segregate plasmids with E2-binding sites in Sacchromyces cerevisiae. This assay is being used to isolate the mammalian chromosomal protein that interacts with E2 using a human cDNA library. Stability of the E2 protein is regulated by phosphorylation, which leads to ubiquination and proteasomal degradation. We show that casein kinase II is responsible for regulating E2 half-life and the resulting viral genome copy number. Phosphorylation induces a conformational change in the E2 protein that leads to its degradation. In most cervical cancers, papillomavirus DNA is found integrated into cellular chromosomes instead of replicating episomally. This integration disrupts the E1 and/or E2 genes and this has led to the hypothesis that disruption of these regulatory functions is a critical step in malignant progression. To study the mechanism of this progression we have developed a system to immortalize primary human keratinocyte cells containing hybrid papillomavirus genomes that are maintained episomally in the absence of E1 and E2 gene functions. This system is being used to determine the role of the E1 and E2 regulatory functions in keratinocyte growth and differentiation and cervical cancer progression.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Intramural Research (Z01)
Project #
1Z01AI000713-09
Application #
6669582
Study Section
(LVD)
Project Start
Project End
Budget Start
Budget End
Support Year
9
Fiscal Year
2002
Total Cost
Indirect Cost
Name
Niaid Extramural Activities
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Jang, Moon Kyoo; Kwon, Deukwoo; McBride, Alison A (2009) Papillomavirus E2 proteins and the host BRD4 protein associate with transcriptionally active cellular chromatin. J Virol 83:2592-600
Cardenas-Mora, Juan; Spindler, Jonathan E; Jang, Moon Kyoo et al. (2008) Dimerization of the papillomavirus E2 protein is required for efficient mitotic chromosome association and Brd4 binding. J Virol 82:7298-305
McPhillips, M G; Oliveira, J G; Spindler, J E et al. (2006) Brd4 is required for e2-mediated transcriptional activation but not genome partitioning of all papillomaviruses. J Virol 80:9530-43
Soeda, Emiko; Ferran, Maureen C; Baker, Carl C et al. (2006) Repression of HPV16 early region transcription by the E2 protein. Virology 351:29-41
Garcia-Alai, Maria M; Gallo, Mariana; Salame, Marcelo et al. (2006) Molecular basis for phosphorylation-dependent, PEST-mediated protein turnover. Structure 14:309-19
Oliveira, Jaquelline G; Colf, Leremy A; McBride, Alison A (2006) Variations in the association of papillomavirus E2 proteins with mitotic chromosomes. Proc Natl Acad Sci U S A 103:1047-52
McBride, Alison A; Oliveira, Jaquelline G; McPhillips, Maria G (2006) Partitioning viral genomes in mitosis: same idea, different targets. Cell Cycle 5:1499-502
Zheng, Peng-Sheng; Brokaw, Jane; McBride, Alison A (2005) Conditional mutations in the mitotic chromosome binding function of the bovine papillomavirus type 1 E2 protein. J Virol 79:1500-9
Baxter, Michael K; McBride, Alison A (2005) An acidic amphipathic helix in the Bovine Papillomavirus E2 protein is critical for DNA replication and interaction with the E1 protein. Virology 332:78-88
Brannon, Angela R; Maresca, Julia A; Boeke, Jef D et al. (2005) Reconstitution of papillomavirus E2-mediated plasmid maintenance in Saccharomyces cerevisiae by the Brd4 bromodomain protein. Proc Natl Acad Sci U S A 102:2998-3003

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