Repository logo
 

CCCTC-binding factor recruitment to the early region of the human papillomavirus 18 genome regulates viral oncogene expression.


Change log

Authors

Paris, Christian 
Pentland, Ieisha 
Roberts, David C 
Powis, Simon J 

Abstract

UNLABELLED: Host cell differentiation-dependent regulation of human papillomavirus (HPV) gene expression is required for productive infection. The host cell CCCTC-binding factor (CTCF) functions in genome-wide chromatin organization and gene regulation. We have identified a conserved CTCF binding site in the E2 open reading frame of high-risk HPV types. Using organotypic raft cultures of primary human keratinocytes containing high-risk HPV18 genomes, we show that CTCF recruitment to this conserved site regulates viral gene expression in differentiating epithelia. Mutation of the CTCF binding site increases the expression of the viral oncoproteins E6 and E7 and promotes host cell proliferation. Loss of CTCF binding results in a reduction of a specific alternatively spliced transcript expressed from the early gene region concomitant with an increase in the abundance of unspliced early transcripts. We conclude that high-risk HPV types have evolved to recruit CTCF to the early gene region to control the balance and complexity of splicing events that regulate viral oncoprotein expression. IMPORTANCE: The establishment and maintenance of HPV infection in undifferentiated basal cells of the squamous epithelia requires the activation of a subset of viral genes, termed early genes. The differentiation of infected cells initiates the expression of the late viral transcripts, allowing completion of the virus life cycle. This tightly controlled balance of differentiation-dependent viral gene expression allows the virus to stimulate cellular proliferation to support viral genome replication with minimal activation of the host immune response, promoting virus productivity. Alternative splicing of viral mRNAs further increases the complexity of viral gene expression. In this study, we show that the essential host cell protein CTCF, which functions in genome-wide chromatin organization and gene regulation, is recruited to the HPV genome and plays an essential role in the regulation of early viral gene expression and transcript processing. These data highlight a novel virus-host interaction important for HPV pathogenicity.

Description

Keywords

Binding Sites, CCCTC-Binding Factor, Cells, Cultured, DNA, Viral, DNA-Binding Proteins, Gene Expression, Gene Expression Regulation, Viral, Host-Pathogen Interactions, Human papillomavirus 18, Humans, Keratinocytes, Oncogene Proteins, Viral, Protein Binding, Repressor Proteins

Journal Title

J Virol

Conference Name

Journal ISSN

0022-538X
1098-5514

Volume Title

89

Publisher

American Society for Microbiology
Sponsorship
Cancer Research Uk (None)
CP was supported by a PhD studentship funded by the University of St Andrews, School of Medicine. IP is supported by a Cancer Research UK (CRUK) PhD Studentship awarded to JLP and SR. IG and NC are supported by a CRUK Programme Award (13080) to NC. JLP is supported by a Royal Society University Research Fellowship (UF110010).