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

2018 ◽  
Vol 14 (2) ◽  
pp. e1006890 ◽  
Author(s):  
Agnieszka Szymula ◽  
Richard D. Palermo ◽  
Amr Bayoumy ◽  
Ian J. Groves ◽  
Mohammed Ba abdullah ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
Viral Genome ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Correction: Epstein-Barr virus nuclear antigen EBNA-LP is essential for transforming naïve B cells, and facilitates recruitment of transcription factors to the viral genome

2019 ◽  
Vol 15 (2) ◽  
pp. e1007403
Author(s):  
Agnieszka Szymula ◽  
Richard D. Palermo ◽  
Amr Bayoumy ◽  
Ian J. Groves ◽  
Mohammed Ba abdullah ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
Viral Genome ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Epstein-Barr Virus Nuclear Antigen Leader Protein Coactivates EP300

2018 ◽  
Vol 92 (9) ◽  
Author(s):  
Chong Wang ◽  
Hufeng Zhou ◽  
Yong Xue ◽  
Jun Liang ◽  
Yohei Narita ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Transcription Activator ◽  
Lymphoproliferative Diseases ◽  
Barr Virus ◽  
Leader Protein ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus nuclear antigen (EBNA) leader protein (EBNALP) is one of the first viral genes expressed upon B-cell infection. EBNALP is essential for EBV-mediated B-cell immortalization. EBNALP is thought to function primarily by coactivating EBNA2-mediated transcription. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) studies highlight that EBNALP frequently cooccupies DNA sites with host cell transcription factors (TFs), in particular, EP300, implicating a broader role in transcription regulation. In this study, we investigated the mechanisms of EBNALP transcription coactivation through EP300. EBNALP greatly enhanced EP300 transcription activation when EP300 was tethered to a promoter. EBNALP coimmunoprecipitated endogenous EP300 from lymphoblastoid cell lines (LCLs). EBNALP W repeat serine residues 34, 36, and 63 were required for EP300 association and coactivation. Deletion of the EP300 histone acetyltransferase (HAT) domain greatly reduced EBNALP coactivation and abolished the EBNALP association. An EP300 bromodomain inhibitor also abolished EBNALP coactivation and blocked the EP300 association with EBNALP. EBNALP sites cooccupied by EP300 had significantly higher ChIP-seq signals for sequence-specific TFs, including SPI1, RelA, EBF1, IRF4, BATF, and PAX5. EBNALP- and EP300-cooccurring sites also had much higher H3K4me1 and H3K27ac signals, indicative of activated enhancers. EBNALP-only sites had much higher signals for DNA looping factors, including CTCF and RAD21. EBNALP coactivated reporters under the control of NF-κB or SPI1. EP300 inhibition abolished EBNALP coactivation of these reporters. Clustered regularly interspaced short palindromic repeat interference targeting of EBNALP enhancer sites significantly reduced target gene expression, including that of EP300 itself. These data suggest a previously unrecognized mechanism by which EBNALP coactivates transcription through subverting of EP300 and thus affects the expression of LCL genes regulated by a broad range of host TFs.IMPORTANCEEpstein-Barr virus was the first human DNA tumor virus discovered over 50 years ago. EBV is causally linked to ∼200,000 human malignancies annually. These cancers include endemic Burkitt lymphoma, Hodgkin lymphoma, lymphoma/lymphoproliferative disease in transplant recipients or HIV-infected people, nasopharyngeal carcinoma, and ∼10% of gastric carcinoma cases. EBV-immortalized human B cells faithfully model key aspects of EBV lymphoproliferative diseases and are useful models of EBV oncogenesis. EBNALP is essential for EBV to transform B cells and transcriptionally coactivates EBNA2 by removing repressors from EBNA2-bound DNA sites. Here, we found that EBNALP can also modulate the activity of the key transcription activator EP300, an acetyltransferase that activates a broad range of transcription factors. Our data suggest that EBNALP regulates a much broader range of host genes than was previously appreciated. A small-molecule inhibitor of EP300 abolished EBNALP coactivation of multiple target genes. These findings suggest novel therapeutic approaches to control EBV-associated lymphoproliferative diseases.

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

2017 ◽  
Author(s):  
Agnieszka Szymula ◽  
Richard D. Palermo ◽  
Ian J. Groves ◽  
Mohammed Ba abdullah ◽  
Beth S. Holder ◽  
...  
Keyword(s):  
B Cells ◽  
Viral Genome ◽  
Epstein Barr Virus ◽  
Gene Activation ◽  
Nuclear Antigen ◽  
Virus Protein ◽  
Barr Virus ◽  
Ebv Infection ◽  
Epstein Barr ◽  
Host Genes

AbstractThe 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.We 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.Quantitative 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.We 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.Author 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.We 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.This 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.

scholarly journals The Epstein-Barr virus (EBV) nuclear antigen 1 BamHI F promoter is activated on entry of EBV-transformed B cells into the lytic cycle.

1992 ◽  
Vol 66 (12) ◽  
pp. 7461-7468 ◽  
Author(s):  
A L Lear ◽  
M Rowe ◽  
M G Kurilla ◽  
S Lee ◽  
S Henderson ◽  
...  
Keyword(s):  
B Cells ◽  
Epstein Barr Virus ◽  
Lytic Cycle ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Endogenous Presentation of CD8+ T Cell Epitopes from Epstein-Barr Virus–encoded Nuclear Antigen 1

2004 ◽  
Vol 199 (10) ◽  
pp. 1421-1431 ◽  
Author(s):  
Judy Tellam ◽  
Geoff Connolly ◽  
Katherine J. Green ◽  
John J. Miles ◽  
Denis J. Moss ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Antigen Processing ◽  
Epstein Barr Virus ◽  
Cd8 T Cell ◽  
Nuclear Antigen ◽  
T Cell Epitopes ◽  
Barr Virus ◽  
Degradation Rates ◽  
Epstein Barr

Epstein-Barr virus (EBV)–encoded nuclear antigen (EBNA)1 is thought to escape cytotoxic T lymphocyte (CTL) recognition through either self-inhibition of synthesis or by blockade of proteasomal degradation by the glycine-alanine repeat (GAr) domain. Here we show that EBNA1 has a remarkably varied cell type–dependent stability. However, these different degradation rates do not correspond to the level of major histocompatibility complex class I–restricted presentation of EBNA1 epitopes. In spite of the highly stable expression of EBNA1 in B cells, CTL epitopes derived from this protein are efficiently processed and presented to CD8+ T cells. Furthermore, we show that EBV-infected B cells can readily activate EBNA1-specific memory T cell responses from healthy virus carriers. Functional assays revealed that processing of these EBNA1 epitopes is proteasome and transporter associated with antigen processing dependent. We also show that the endogenous presentation of these epitopes is dependent on the newly synthesized protein rather than the long-lived stable EBNA1. Based on these observations, we propose that defective ribosomal products, not the full-length antigen, are the primary source of endogenously processed CD8+ T cell epitopes from EBNA1.

scholarly journals Early events in Epstein-Barr virus infection provide a model for B cell activation.

1985 ◽  
Vol 162 (1) ◽  
pp. 45-59 ◽  
Author(s):  
D A Thorley-Lawson ◽  
K P Mann
Keyword(s):  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Rna Synthesis ◽  
Cell Activation ◽  
Nuclear Antigen ◽  
Epstein Barr Virus Infection ◽  
B Cell Activation ◽  
Barr Virus ◽  
Epstein Barr

We have used Epstein-Barr virus (EBV) infection in vitro to delineate two distinct stages in B cell activation. Previous studies have shown that the BLAST-2 (EBVCS) (EBV cell surface) activation antigen is expressed on a small fraction of B cells within 24 h of stimulation with a variety of agents, including mitogens and EBV. In this study, we have been able to isolate the BLAST-2 (EBVCS)+ cells early after activation/infection with EBV. These cells are small B cells that are actively synthesizing RNA but not DNA, and are, therefore, clearly distinct from large proliferating lymphoblasts. In addition, they contain multiple copies of the EBV genome, express the viral nuclear antigen (EBNA) and, most importantly, proceed to undergo transformation when placed back in culture. By comparison, the BLAST-2 (EBVCS)- population does not undergo transformation, even though a fraction of these cells are activated for RNA synthesis and express EBNA. Thus, using the EBV system, we have been able to show directly that an activated B cell first expresses the BLAST-2 (EBVCS) antigen concomitant with an increase in RNA synthesis, and then subsequently proceeds to differentiate into a proliferating lymphoblast.

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