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Groves, I. J.

Publications and source records attributed to Groves, I. J..

2 recordsLinked to original sources
bioRxiv2018

Increased Epstein-Barr virus C-promoter activity with CTCF-binding site deletion is associated with elevated EBNA2 recruitment.

The regulation of transcription from Epstein-Barr virus promoters is known to involve the association of the host CCCTC-binding factor (CTCF) protein. This control involves direct binding of CTCF across the EBV genome and the formation of three-dimensional loops between virus promoters and enhancers. We sought to address how the deletion of a CTCF binding site upstream of the C-promoter (Cp) affected viral transcription in infected lymphoblastoid cell lines (LCLs) and how binding of the EBV trans-activating protein EBNA2 was changed across this promoter. Transcript level from Cp was up-regulated with CTCF binding site deletion, and transcription from other promoters (Wp and Qp) was decreased, while transcript levels were largely unchanged by independent mutation of a Cp-RBPJ{kappa} binding site. In turn, expression of EBNA2 protein was also increased, likely driven by increases in polycistronic EBNA2-encoding transcripts. Finally, Cp up-regulation was associated with an 8-fold increase in EBNA2 enrichment across Cp, concomitant with increased association of the associated cellular factor RBPJ{kappa}, probably due to a more accessible three-dimensional chromatin conformation upstream of Cp. Overall, the data presented here confirm that binding of CTCF directly upstream of Cp is important for the regulation of transcription from this and other EBV promoters.

microbiology↗
bioRxiv2017

Epstein-Barr virus nuclear antigen EBNA-LP is essential for transforming naive B cells, and facilitates recruitment of transcription factors to the viral genome.

The Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) is the first viral latency-associated protein produced after EBV infection of resting B cells. Its role in B cell transformation is poorly defined, but it is reported to enhance gene activation by the EBV protein EBNA2 in vitro.\n\nWe generated two sets of EBNA-LP knockout (LPKO) EBVs containing a STOP codon within each repeat unit of IR1. Intronic mutations in the first of these knockouts suggested a role for the EBV sisRNAs in transformation. LPKOs with intact introns established lymphoblastoid cell lines (LCLs) from adult B cells at reduced efficiency, but umbilical cord B cells, and naive (IgD+, CD27-) adult B cells consistently died approximately two weeks after infection with LPKO, failing to establish LCLs.\n\nQuantitative PCR analysis of virus gene expression after infection identified both an altered ratio of the EBNA genes, and a dramatic reduction in transcript levels of both EBNA2-regulated virus genes (LMP1 and LMP2) and the EBNA2-independent EBER genes, particularly in the first 1-2 weeks. By 30 days post infection, these levels had equalised. In contrast, EBNA2-regulated host genes were induced efficiently by LPKO viruses. Chromatin immunoprecipitation revealed that recruitment of EBNA2 and the host factors EBF1 and RBPJ to all latency promoters tested was severely delayed, whereas these same factors were recruited efficiently to several host genes, some of which exhibited increased EBNA2 recruitment.\n\nWe conclude that EBNA-LP does not simply co-operate with EBNA2 in activating gene transcription, but rather facilitates the recruitment of several transcription factors to the viral genome, to enable transcription of virus latency genes. Additionally, our findings suggest that different properties of EBV may have differing importance in transforming different B cell subsets.\n\nAuthor summaryEpstein-Barr virus (EBV) infects almost everyone. Once infected, people harbor the virus for life, shedding it in saliva. Infection of children is asymptomatic, but a first infection during adolescence or adulthood can cause glandular fever (mono). EBV is also implicated in several different cancers. EBV infection of B cells (the immune cell that produces antibodies) can drive them to replicate almost indefinitely ( transformation), generating cell lines. We have investigated the role of a virus protein - EBNA-LP - which is thought to support gene activation by the essential virus protein EBNA2.\n\nWe have made an EBV in which the EBNA-LP gene has been disrupted. This virus (LPKO) shows several properties. 1. It is reduced in its ability to transform adult cells, while immature B cells (more frequent in the young) die two weeks after LPKO infection. 2. Some virus genes fail to turn on immediately after LPKO infection. 3. Binding of EBNA2 to these genes is delayed, as is binding of some cellular factors. 4. EBNA-LP does not affect EBNA2-targeted cellular genes in the same way.\n\nThis shows that EBNA-LP is more important in immature cells, and that it regulates virus genes - but not host genes - more widely than simply through EBNA2.

microbiology↗