Evidence supporting a role for TopBP1 and Brd4 in the initiation but not continuation of human papillomavirus 16 E1/E2-mediated DNA replication

Gauson, E. J., Donaldson, M. , Dornan, E. S., Wang, X., Bristol, M., Bodily, J. M. and Morgan, I. M. (2015) Evidence supporting a role for TopBP1 and Brd4 in the initiation but not continuation of human papillomavirus 16 E1/E2-mediated DNA replication. Journal of Virology, 89(9), pp. 4980-4991. (doi:10.1128/JVI.00335-15) (PMID:25694599) (PMCID:PMC4403487)

Gauson, E. J., Donaldson, M. , Dornan, E. S., Wang, X., Bristol, M., Bodily, J. M. and Morgan, I. M. (2015) Evidence supporting a role for TopBP1 and Brd4 in the initiation but not continuation of human papillomavirus 16 E1/E2-mediated DNA replication. Journal of Virology, 89(9), pp. 4980-4991. (doi:10.1128/JVI.00335-15) (PMID:25694599) (PMCID:PMC4403487)

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Abstract

To replicate the double-stranded human papillomavirus 16 (HPV16) DNA genome, viral proteins E1 and E2 associate with the viral origin of replication, and E2 can also regulate transcription from adjacent promoters. E2 interacts with host proteins in order to regulate both transcription and replication; TopBP1 and Brd4 are cellular proteins that interact with HPV16 E2. Previous work with E2 mutants demonstrated the Brd4 requirement for the transactivation properties of E2, while TopBP1 is required for DNA replication induced by E2 from the viral origin of replication in association with E1. More-recent studies have also implicated Brd4 in the regulation of DNA replication by E2 and E1. Here, we demonstrate that both TopBP1 and Brd4 are present at the viral origin of replication and that interaction with E2 is required for optimal initiation of DNA replication. Both cellular proteins are present in E1-E2-containing nuclear foci, and the viral origin of replication is required for the efficient formation of these foci. Short hairpin RNA (shRNA) against either TopBP1 or Brd4 destroys the E1-E2 nuclear bodies but has no effect on E1-E2-mediated levels of DNA replication. An E2 mutation in the context of the complete HPV16 genome that compromises Brd4 interaction fails to efficiently establish episomes in primary human keratinocytes. Overall, the results suggest that interactions between TopBP1 and E2 and between Brd4 and E2 are required to correctly initiate DNA replication but are not required for continuing DNA replication, which may be mediated by alternative processes such as rolling circle amplification and/or homologous recombination.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Dornan, Mr Edward and Morgan, Professor Iain and Donaldson, Dr Mary
Authors: Gauson, E. J., Donaldson, M., Dornan, E. S., Wang, X., Bristol, M., Bodily, J. M., and Morgan, I. M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Journal of Virology
Publisher:American Society for Microbiology
ISSN:0022-538X
ISSN (Online):1098-5514
Copyright Holders:Copyright © 2015 American Society for Microbiology
First Published:First published in Journal of Virology 89(9):4980-4991
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
556081Interaction between the essential replication factor TopBP1 and human papillomavirus 16 E1: a novel antiviral targetIain MorganCancer Research UK (CAN-RES-UK)12695MVLS III - CENTRE FOR VIRUS RESEARCH