Regulation of transcription by the Epstein–Barr virus nuclear antigen EBNA 2

2008 ◽  
Vol 36 (4) ◽  
pp. 625-628 ◽  
Author(s):  
Richard D. Palermo ◽  
Helen M. Webb ◽  
Andrea Gunnell ◽  
Michelle J. West
Keyword(s):  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Nuclear Antigen ◽  
Regulation Of Transcription ◽  
Cyclin Dependent Kinase ◽  
Barr Virus ◽  
General Transcription Factors ◽  
Nuclear Antigens ◽  
Infected Cells ◽  
Epstein Barr

The EBNA 2 (Epstein–Barr nuclear antigen 2) transcription factor is essential for B-cell transformation by the cancer-associated EBV (Epstein–Barr virus) and for the continuous proliferation of infected cells. EBNA 2 activates transcription from the viral Cp (C promoter) during infection to generate the 120 kb transcript that encodes all nuclear antigens required for immortalization by EBV. EBNA 2 contains an acidic activation domain and can interact with a number of general transcription factors and co-activators. It is now becoming clear, however, that the regulation of transcription elongation in addition to initiation by EBNA 2, at least in part through CDK9 (cyclin-dependent kinase 9)-dependent phosphorylation of the RNA polymerase C-terminal domain, is likely to play a crucial role in the mechanism of action of this key viral protein.

scholarly journals Epstein-Barr Virus Nuclear Antigen 3A Promotes Cellular Proliferation by Repression of the Cyclin-Dependent Kinase Inhibitor p21WAF1/CIP1

2014 ◽  
Vol 10 (10) ◽  
pp. e1004415 ◽  
Author(s):  
Melissa L. Tursiella ◽  
Emily R. Bowman ◽  
Keith C. Wanzeck ◽  
Robert E. Throm ◽  
Jason Liao ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Nuclear Antigen ◽  
Cyclin Dependent Kinase ◽  
Barr Virus ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Epstein Barr

scholarly journals Epstein-Barr Virus EBNA-3C Is Targeted to and Regulates Expression from the Bidirectional LMP-1/2B Promoter

2006 ◽  
Vol 80 (22) ◽  
pp. 11200-11208 ◽  
Author(s):  
Carmilia Jiménez-Ramírez ◽  
Andrew J. Brooks ◽  
Linus Plym Forshell ◽  
Konstantin Yakimchuk ◽  
Bo Zhao ◽  
...  
Keyword(s):  
Cell Line ◽  
Epstein Barr Virus ◽  
Normal Growth ◽  
Growth Conditions ◽  
Nuclear Antigen ◽  
Regulation Of Transcription ◽  
Gene Promoters ◽  
Viral Oncoprotein ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is essential for EBV-mediated immortalization of human B lymphocytes and regulates both the cell cycle and transcription. Transient reporter gene assays have implicated a pivotal role for EBNA-3C in the regulation of transcription of the majority of latency-associated genes expressed during the EBV growth program, including the viral oncoprotein LMP-1. To examine the regulation of latency gene expression by EBNA-3C, we generated an EBV-positive cell line that inducibly expresses EBNA-3C. This cell line allowed us to examine expression from the endogenous latency gene promoters in the context of an actual latent infection and the presence of other EBNA proteins, in particular EBNA-2, which is presumed to coregulate transcription with EBNA-3C. EBNA-3C induced the expression of both LMP-1 and LMP-2B mRNAs from the bidirectional LMP-1/LMP-2B promoter. In contrast, no effect was seen on expression from the common EBNA promoter Cp, which is responsive to EBNA-3C in reporter assays. Activation of LMP expression was not the consequence of increases in EBNA-2, PU.1 or Spi-B transcription factors, all of which are believed to be critical for activation of LMP-1. Chromatin immunoprecipitation assays furthermore indicated that EBNA-3C is present at the bidirectional LMP-1/LMP-2B promoter. These results indicate that EBNA-3C directly activates the expression of LMP-1 and LMP-2B but is unlikely to significantly regulate EBNA expression via Cp under normal growth conditions.

scholarly journals The CR4 region of EBNA2 confers viability of Epstein–Barr virus-transformed B cells by CBF1-independent signalling

2006 ◽  
Vol 87 (11) ◽  
pp. 3169-3176 ◽  
Author(s):  
Kristina Grabusic ◽  
Sabine Maier ◽  
Andrea Hartmann ◽  
Anja Mantik ◽  
Wolfgang Hammerschmidt ◽  
...  
Keyword(s):  
B Cells ◽  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Mutant Virus ◽  
Nuclear Antigen ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Barr Virus ◽  
Epstein Barr ◽  
Cell Densities

The Epstein–Barr virus (EBV) nuclear antigen 2 (EBNA2) gene product is the key regulator of the latent genes of EBV and essential for EBV-mediated transformation of human primary B cells. Viral mutants were constructed carrying a deletion of the EBNA2 conserved region 4 (CR4). Primary resting B cells infected with the ΔCR4-EBNA2 mutant virus were dramatically impaired for B cell transformation. Lymphoblastoid cell lines (LCLs) established with this mutant EBV revealed a prolonged population doubling time when cells were cultivated at low cell densities, which are not critical for wild-type-infected cells. Low-level spontaneous cell death occurred when the cells were cultivated at suboptimal cell densities. The phenotype of B cells and LCLs infected with the ΔCR4-EBNA2 mutant virus indicated that the CR4 region of EBNA2 specifically contributes to the viability of the cells rather than affecting cell division rates.

scholarly journals Plasmacytic differentiation of circulating Epstein-Barr virus-infected B lymphocytes during acute infectious mononucleosis.

1981 ◽  
Vol 153 (2) ◽  
pp. 235-244 ◽  
Author(s):  
J E Robinson ◽  
D Smith ◽  
J Niederman
Keyword(s):  
Infectious Mononucleosis ◽  
Epstein Barr Virus ◽  
Plasma Cells ◽  
Phase 1 ◽  
Acute Disease ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Infected Cells ◽  
Epstein Barr ◽  
Acute Infectious Mononucleosis

During the acute phase (1 wk of symptoms or less) of infectious mononucleosis (IM), 70--80% of circulating Epstein-Barr virus nuclear antigen (EBNA)-positive cells have differentiated toward plasma cells. Thus the characteristics of the infected cells in the majority of IM patients during early disease are indistinguishable from EBNA-positive tumor cells of a previously reported child who developed lymphoma during IM. IgA and IgG were the most frequent and IgM the least frequent immunoglobulin isotypes detected in EBNA-positive cells. In acute disease EBNA was present in 5.5--20% of T cell-depleted blood lymphocytes but in the 2nd or 3rd wk of illness the number of EBNA-positive cells sharply decreased to 0.4--1.4%. At the same time the fraction of antigen-positive cells containing cytoplasmic immunoglobulins also diminished, suggesting either that differentiation of infected cells was altered during the disease or that nondifferentiated antigen-positive cells had a survival advantage. Both the high proportion of plasmacytic EBNA-positive cells seen during acute disease and the apparent loss of differentiation by these cells later in disease may be regulated by host immunologic factors. Immunoglobulin-producing EBNA-positive cells may be the source of heterophile antibodies and other seemingly inappropriate antibodies usually found in serum during IM; however, increased numbers of noninfected plasma cells were present in some patients and may also be a potential source of these unusual antibodies.

scholarly journals Epstein–Barr virus nuclear antigen (EBNA) 3A induces the expression of and interacts with a subset of chaperones and co-chaperones

2008 ◽  
Vol 89 (4) ◽  
pp. 866-877 ◽  
Author(s):  
Paul Young ◽  
Emma Anderton ◽  
Kostas Paschos ◽  
Rob White ◽  
Martin J. Allday
Keyword(s):  
Epstein Barr Virus ◽  
Expression System ◽  
Nuclear Antigen ◽  
Human Diploid Fibroblasts ◽  
Barr Virus ◽  
Cellular Genes ◽  
Infected Cells ◽  
Epstein Barr ◽  
Chaperone Complex

Viral nuclear oncoproteins EBNA3A and EBNA3C are essential for the efficient immortalization of B cells by Epstein–Barr virus (EBV) in vitro and it is assumed that they play an essential role in viral persistence in the human host. In order to identify cellular genes regulated by EBNA3A expression, cDNA encoding EBNA3A was incorporated into a recombinant adenoviral vector. Microarray analysis of human diploid fibroblasts infected with either adenovirus EBNA3A or an empty control adenovirus consistently showed an EBNA3A-specific induction of mRNA corresponding to the chaperones Hsp70 and Hsp70B/B′ and co-chaperones Bag3 and DNAJA1/Hsp40. Analysis of infected fibroblasts by real-time quantitative RT-PCR and Western blotting confirmed that EBNA3A, but not EBNA3C, induced expression of Hsp70, Hsp70B/B′, Bag3 and DNAJA1/Hsp40. This was also confirmed in a stable, inducible expression system. EBNA3A activated transcription from the Hsp70B promoter, but not multimerized heat-shock elements in transient transfection assays, consistent with specific chaperone and co-chaperone upregulation. Co-immunoprecipitation experiments suggest that EBNA3A can form a complex with the chaperone/co-chaperone proteins in both adenovirus-infected cells and EBV-immortalized lymphoblastoid cell lines. Consistent with this, induction of EBNA3A resulted in redistribution of Hsp70 from the cytoplasm to the nucleus. EBNA3A therefore specifically induces (and then interacts with) all of the factors necessary for an active Hsp70 chaperone complex.

scholarly journals Genetic analysis of the Epstein–Barr virus-coded leader protein EBNA-LP as a co-activator of EBNA2 function

2001 ◽  
Vol 82 (12) ◽  
pp. 3067-3079 ◽  
Author(s):  
Eamon M. McCann ◽  
Gemma L. Kelly ◽  
Alan B. Rickinson ◽  
Andrew I. Bell
Keyword(s):  
Genetic Analysis ◽  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Lmp1 Expression ◽  
Leader Protein ◽  
Epstein Barr ◽  
The Individual ◽  
Unique Domain

Co-operation between the Epstein–Barr virus (EBV)-coded leader protein EBNA-LP and the nuclear antigen EBNA2 appears to be critical for efficient virus-induced B cell transformation. Here we report the genetic analysis of EBNA-LP function using two transient co-transfection assays of co-operativity, activation of latent membrane protein 1 (LMP1) expression from a resident EBV genome in Akata-BL cells and activation of an EBNA2-responsive reporter construct. Small deletions were introduced into each of five conserved regions (CRs) of EBNA-LP sequence present in type 1 and type 2 EBV strains and in several primate lymphocryptovirus EBNA-LP homologues. Deletions within all three CRs in the EBNA-LP W1W2 repeat domain completely abrogated function, through inhibition of nuclear localization in the cases of CR1 and CR2 but not of CR3; deletions within CR4 and CR5 in the Y1Y2 unique domain had relatively little effect, yet loss of the whole Y2 sequence blocked activity. Alanine substitution of serine residues within potential phosphorylation sites identified two mutants of particular interest. Substitution of three such residues (S34,36,63) within W1W2 not only abrogated EBNA-LP activity but was associated with a complete loss of EBNA2 detectability in co-transfected cells, implying possible destabilization of the co-expressed EBNA2 protein. More importantly the individual substitution of S36 completely blocked EBNA-LP/EBNA2 co-operativity while retaining EBNA2 expression. We infer critical roles for the CR3 domain and for the S36 residue in EBNA-LP’s co-operative function.

scholarly journals Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis

2020 ◽  
Vol 117 (25) ◽  
pp. 14421-14432
Author(s):  
Thomas Sommermann ◽  
Tomoharu Yasuda ◽  
Jonathan Ronen ◽  
Tristan Wirtz ◽  
Timm Weber ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Plasma Cells ◽  
Cell Transformation ◽  
Barr Virus ◽  
Nuclear Antigens ◽  
Epstein Barr ◽  
Cell Transforming ◽  
Early B Cell Factor

Epstein-Barr virus (EBV) is a B cell transforming virus that causes B cell malignancies under conditions of immune suppression. EBV orchestrates B cell transformation through its latent membrane proteins (LMPs) and Epstein-Barr nuclear antigens (EBNAs). We here identify secondary mutations in mouse B cell lymphomas induced by LMP1, to predict and identify key functions of other EBV genes during transformation. We find aberrant activation of early B cell factor 1 (EBF1) to promote transformation of LMP1-expressing B cells by inhibiting their differentiation to plasma cells. EBV EBNA3A phenocopies EBF1 activities in LMP1-expressing B cells, promoting transformation while inhibiting differentiation. In cells expressing LMP1 together with LMP2A, EBNA3A only promotes lymphomagenesis when the EBNA2 target Myc is also overexpressed. Collectively, our data support a model where proproliferative activities of LMP1, LMP2A, and EBNA2 in combination with EBNA3A-mediated inhibition of terminal plasma cell differentiation critically control EBV-mediated B cell lymphomagenesis.

scholarly journals Epstein–Barr virus nuclear antigen 3A protein regulates CDKN2B transcription via interaction with MIZ-1

2014 ◽  
Vol 42 (15) ◽  
pp. 9700-9716 ◽  
Author(s):  
Quentin Bazot ◽  
Thibaut Deschamps ◽  
Lionel Tafforeau ◽  
Maha Siouda ◽  
Pascal Leblanc ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Target Genes ◽  
Zinc Finger Protein ◽  
Transformation Process ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Trimeric Complex ◽  
Growth Inhibitory ◽  
Infected Cells ◽  
Epstein Barr

AbstractThe Epstein–Barr virus (EBV) nuclear antigen 3 family of protein is critical for the EBV-induced primary B-cell growth transformation process. Using a yeast two-hybrid screen we identified 22 novel cellular partners of the EBNA3s. Most importantly, among the newly identified partners, five are known to play direct and important roles in transcriptional regulation. Of these, the Myc-interacting zinc finger protein-1 (MIZ-1) is a transcription factor initially characterized as a binding partner of MYC. MIZ-1 activates the transcription of a number of target genes including the cell cycle inhibitor CDKN2B. Focusing on the EBNA3A/MIZ-1 interaction we demonstrate that binding occurs in EBV-infected cells expressing both proteins at endogenous physiological levels and that in the presence of EBNA3A, a significant fraction of MIZ-1 translocates from the cytoplasm to the nucleus. Moreover, we show that a trimeric complex composed of a MIZ-1 recognition DNA element, MIZ-1 and EBNA3A can be formed, and that interaction of MIZ-1 with nucleophosmin (NPM), one of its coactivator, is prevented by EBNA3A. Finally, we show that, in the presence of EBNA3A, expression of the MIZ-1 target gene, CDKN2B, is downregulated and repressive H3K27 marks are established on its promoter region suggesting that EBNA3A directly counteracts the growth inhibitory action of MIZ-1.

scholarly journals Epstein-Barr Virus Nuclear Antigen 3C and Prothymosin Alpha Interact with the p300 Transcriptional Coactivator at the CH1 and CH3/HAT Domains and Cooperate in Regulation of Transcription and Histone Acetylation

2002 ◽  
Vol 76 (10) ◽  
pp. 4699-4708 ◽  
Author(s):  
Chitra Subramanian ◽  
Sameez Hasan ◽  
Martin Rowe ◽  
Michael Hottiger ◽  
Rama Orre ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Regulation Of Transcription ◽  
Transcriptional Coactivator ◽  
Prothymosin Alpha ◽  
Barr Virus ◽  
Amino Terminal ◽  
Epstein Barr ◽  
Coactivator P300

ABSTRACT The Epstein-Barr virus nuclear antigen 3C (EBNA3C), encoded by Epstein-Barr virus (EBV), is essential for mediating transformation of human B lymphocytes. Previous studies demonstrated that EBNA3C interacts with a small, nonhistone, highly acidic, high-mobility group-like nuclear protein prothymosin alpha (ProTα) and the transcriptional coactivator p300 in complexes from EBV-infected cells. These complexes were shown to be associated with histone acetyltransferase (HAT) activity in that they were able to acetylate crude histones in vitro. In this report we show that ProTα interacts with p300 similarly to p53 and other known oncoproteins at the CH1 amino-terminal domain as well as at a second domain downstream of the bromodomain which includes the CH3 region and HAT domain. Similarly, EBNA3C also interacts with p300 at regions which include the CH1 and CH3/HAT domains, suggesting that ProTα and EBNAC3C may interact in a complex with p300. We also show that ProTα activates transcription when targeted to promoters by fusion to the GAL4 DNA binding domain and that this activation is enhanced by the addition of an exogenous source of p300 under the control of a heterologous promoter. This overall activity is down-modulated in the presence of EBNA3C. These results further establish the interaction of cellular coactivator p300 with ProTα and demonstrate that the associated activities resulting from this interaction, which plays a role in acetylation of histones and coactivation, can be regulated by EBNA3C. Furthermore, this study establishes for the first time a transcriptional role for ProTα in recruitment or stabilization of coactivator p300, as well as other basal transcription factors, at the nucleosomes for regulation of transcription.

scholarly journals Functional Interaction of Nuclear Factor Y and Sp1 Is Required for Activation of the Epstein-Barr Virus C Promoter

2003 ◽  
Vol 77 (2) ◽  
pp. 821-829 ◽  
Author(s):  
Cecilia Boreström ◽  
Henrik Zetterberg ◽  
Kristian Liff ◽  
Lars Rymo
Keyword(s):  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Dominant Negative ◽  
Nuclear Antigen ◽  
Nuclear Factor ◽  
Barr Virus ◽  
Nuclear Factor Y ◽  
Epstein Barr ◽  
B Lymphoid ◽  
Virus C

ABSTRACT Two Epstein-Barr virus (EBV) latent cycle promoters, Wp and Cp, are activated sequentially during virus-induced transformation of primary B lymphocytes. Immediately postinfection, viral transcription initiates from Wp, leading to expression of EBV nuclear antigen 2 (EBNA2) and EBNA5. Within 36 h, there is a switch in promoter usage from Wp to the upstream Cp, which leads to expression of EBNA1 to EBNA6. EBNA2 appears to be required for the Wp-to-Cp switch, but the switching mechanism is not fully understood at the molecular level. In a previous investigation we showed that there is an EBNA2-independent activity of reporter constructs containing deletion fragments of Cp in B-lymphoid cell lines, and we demonstrated that Cp activity is highly dependent on several cellular transcription factors, including nuclear factor Y (NF-Y) and Sp1. In the present work, we analyzed the effect of NF-Y on Cp activity in greater detail. We demonstrate that (i) a dominant negative analogue of NF-Y abolishes Cp activity, (ii) NF-Y and Sp1 costimulate Cp, and (iii) the oriPI-EBNA1-induced transactivation of Cp requires concomitant expression of NF-Y and Sp1, although additional factors seem necessary for optimal activation. Furthermore, using the lymphoblastoid cell line EREB2-5, in which EBNA2 function is regulated by estrogen, we demonstrate that inactivation of EBNA2 results in decreased expression of NF-Y and down-regulation of Cp. On reconstitution of the EBNA2 function, the cells enter the cell cycle, NF-Y levels increase, and a concomitant Wp-to-Cp switch occurs. Taken together, our results suggest that NF-Y is essential for Cp activation and that up-regulation of NF-Y may contribute to a successful Wp-to-Cp switch during B-cell transformation.

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