scholarly journals IRF-7, a new interferon regulatory factor associated with Epstein-Barr virus latency.

1997 ◽  
Vol 17 (10) ◽  
pp. 5748-5757 ◽  
Author(s):  
L Zhang ◽  
J S Pagano
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Type I ◽  
Blood Leukocytes ◽  
Type Iii ◽  
Barr Virus ◽  
Virus Latency ◽  
Restricted Type ◽  
Epstein Barr

The Epstein-Barr virus (EBV) BamHI Q promoter (Qp) is the only promoter used for the transcription of Epstein-Barr virus nuclear antigen 1 (EBNA-1) mRNA in cells in the most restricted (type I) latent infection state. However, Qp is inactive in type III latency. With the use of the yeast one-hybrid system, a new cellular gene has been identified that encodes proteins which bind to sequence in Qp. The deduced amino acid sequence of the gene has significant homology to the interferon regulatory factors (IRFs). This new gene and products including two splicing variants are designated IRF-7A, IRF-7B, and IRF-7C. The expression of IRF-7 is predominantly in spleen, thymus, and peripheral blood leukocytes (PBL). IRF-7 proteins were identified in primary PBL with specific antiserum against IRF-7B protein. IRF-7s can bind to interferon-stimulated response element (ISRE) sequence and repress transcriptional activation by both interferon and IRF-1. Additionally, a functional viral ISRE sequence, 5'-GCGAAAACGAAAGT-3', has been identified in Qp. Finally, the expression of IRF-7 is consistently high in type III latency cells and almost undetectable in type I latency, corresponding to the activity of endogenous Qp in these latency states and the ability of the IRF-7 proteins to repress Qp-reporter constructs. The identification of a functional viral ISRE and association of IRF-7 with type III latency may be relevant to the mechanism of regulation of Qp.

scholarly journals Interferon Regulatory Factor 2 Represses the Epstein-Barr Virus BamHI Q Latency Promoter in Type III Latency

1999 ◽  
Vol 19 (4) ◽  
pp. 3216-3223 ◽  
Author(s):  
Luwen Zhang ◽  
Joseph S. Pagano
Keyword(s):  
Epstein Barr Virus ◽  
Mrna Level ◽  
Negative Regulator ◽  
Nuclear Antigen ◽  
Major Protein ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is the essential protein for maintenance of the EBV episome and establishment of latency. The BamHI Q promoter (Qp) is used for the transcription of EBNA-1 mRNA in type I and type II latency, which are EBV infection states exemplified by Burkitt’s lymphoma and nasopharyngeal carcinoma. However, Qp is inactive in type III latency, and other promoters (the BamHI C promoter and/or theBamHI W promoter) are used for EBNA-1. The involvement of interferon regulatory factors (IRFs) in the regulation of Qp is suggested by the presence of an essential interferon-stimulated response element (ISRE) in the promoter. In this work, expression of IRF-2 is shown to be inversely associated with Qp status, i.e., IRF-2 levels are high in type III latency (when Qp is inactive) and low in type I latency (when Qp is active). Also, IRF-2 is identified by electrophoretic mobility shift assay as the major protein binding to the Qp ISRE in type III latency. In transient transfection assays, IRF-2 represses the activity of Qp-reporter constructs. Overexpression of IRF-2 in a type I latency cell line did not activate the endogenous Qp but marginally reduced the EBNA-1 mRNA level. Switching from type III latency (Qp inactive) to type II latency (Qp active), as produced by cell fusion, is directly associated with greatly reduced expression of IRF-2. These data strongly suggest that IRF-2 is a negative regulator of Qp and may contribute to the silencing of Qp in type III latency.

scholarly journals The Epstein-Barr Virus EBNA-LP Protein Preferentially Coactivates EBNA2-Mediated Stimulation of Latent Membrane Proteins Expressed from the Viral Divergent Promoter

2005 ◽  
Vol 79 (7) ◽  
pp. 4492-4505 ◽  
Author(s):  
RongSheng Peng ◽  
Stephanie C. Moses ◽  
Jie Tan ◽  
Elisabeth Kremmer ◽  
Paul D. Ling
Keyword(s):  
B Cell ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Type I ◽  
Barr Virus ◽  
Cell Immortalization ◽  
Cellular Cofactor ◽  
Epstein Barr ◽  
Transformed Cell Lines ◽  
Stimulation Of

ABSTRACT The mechanistic contribution of the Epstein-Barr virus (EBV) EBNA-LP protein to B-cell immortalization remains an enigma. However, previous studies have indicated that EBNA-LP may contribute to immortalization by enhancing EBNA2-mediated transcriptional activation of the LMP-1 gene. To gain further insight into the potential role EBNA-LP has in EBV-mediated B-cell immortalization, we asked whether it is a global or gene-specific coactivator of EBNA2 and whether coactivation requires interaction between these proteins. In type I Burkitt's lymphoma cells, we found that EBNA-LP strongly coactivated EBNA2 stimulation of LMP-1 and LMP2B RNAs, which are expressed from the viral divergent promoter. Surprisingly, the viral LMP2A gene and cellular CD21 and Hes-1 genes were induced by EBNA2 but showed no further induction after EBNA-LP coexpression. We also found that EBNA-LP did not stably interact with EBNA2 in coimmunoprecipitation assays, even though the conditions were adequate to observe specific interactions between EBNA2 and its cellular cofactor, CBF1. Colocalization between EBNA2 and EBNA-LP was not detectable in EBV-transformed cell lines or transfected type I Burkitt's cells. Finally, no significant interactions between EBNA2 and EBNA-LP were found with mammalian two-hybrid assays. From this data, we conclude that EBNA-LP is not a global coactivator of EBNA2 targets, but it preferentially coactivates EBNA2 stimulation of the viral divergent promoter. While this may require specific transient interactions between these proteins that only occur in the context of the divergent promoter, our data strongly suggest that EBNA-LP also cooperates with EBNA2 through mechanisms that do not require direct or indirect complex formation between these proteins.

scholarly journals Infection of Epstein–Barr Virus in Type III Latency Modulates Biogenesis of Exosomes and the Expression Profile of Exosomal miRNAs in the Burkitt Lymphoma Mutu Cell Lines

Cancers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 237 ◽  
Author(s):  
Asuka Nanbo ◽  
Harutaka Katano ◽  
Michiyo Kataoka ◽  
Shiho Hoshina ◽  
Tsuyoshi Sekizuka ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Burkitt Lymphoma ◽  
Epstein Barr Virus ◽  
Type I ◽  
Type Iii ◽  
Barr Virus ◽  
Ebv Infection ◽  
Latently Infected ◽  
Infected Cells ◽  
Epstein Barr

Infection of Epstein–Barr virus (EBV), a ubiquitous human gamma herpesvirus, is associated with various malignancies in B lymphocytes and epithelial cells. EBV encodes 49 microRNAs in two separated regions, termed the BART and BHRF1 loci. Although accumulating evidence demonstrates that EBV infection regulates the profile of microRNAs in the cells, little is known about the microRNAs in exosomes released from infected cells. Here, we characterized the expression profile of intracellular and exosomal microRNAs in EBV-negative, and two related EBV-infected Burkitt lymphoma cell lines having type I and type III latency by next-generation sequencing. We found that the biogenesis of exosomes is upregulated in type III latently infected cells compared with EBV-negative and type I latently infected cells. We also observed that viral and several specific host microRNAs were predominantly incorporated in the exosomes released from the cells in type III latency. We confirmed that multiple viral microRNAs were transferred to the epithelial cells cocultured with EBV-infected B cells. Our findings indicate that EBV infection, in particular in type III latency, modulates the biogenesis of exosomes and the profile of exosomal microRNAs, potentially contributing to phenotypic changes in cells receiving these exosomes.

scholarly journals Mitosis-Specific Hyperphosphorylation of Epstein-Barr Virus Nuclear Antigen 2 Suppresses Its Function

2004 ◽  
Vol 78 (7) ◽  
pp. 3542-3552 ◽  
Author(s):  
Wei Yue ◽  
Matthew G. Davenport ◽  
Julia Shackelford ◽  
Joseph S. Pagano
Keyword(s):  
Epstein Barr Virus ◽  
Regulation Of Gene Expression ◽  
Cyclin B1 ◽  
Nuclear Antigen ◽  
Mrna Levels ◽  
Type Iii ◽  
Barr Virus ◽  
M Phase ◽  
Epstein Barr

ABSTRACT The Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) is a key gene expressed in EBV type III latent infection that can transactivate numerous promoters, including those for all the other type III viral latency genes as well as cellular genes responsible for cell proliferation. EBNA-2 is essential for EBV-mediated immortalization of primary B lymphocytes. We now report that EBNA-2, a phosphoprotein, is hyperphosphorylated specifically in mitosis. Evidence that the cyclin-dependent kinase p34cdc2 may be involved in this hyperphosphorylation includes (i) coimmunoprecipitation of EBNA-2 and p34cdc2, suggesting physical association; (ii) temporal correlation between hyperphosphorylation of EBNA-2 and an increase in p34cdc2 kinase activity; and (iii) ability of purified p34cdc2/cyclin B1 kinase to phosphorylate EBNA-2 in vitro. Hyperphosphorylation of EBNA-2 appears to suppress its ability to transactivate the latent membrane protein 1 (LMP-1) promoter by about 50%. The association between EBNA-2 and PU.1 is also decreased by about 50% in M-phase-arrested cells, as shown by coimmunoprecipitation from cell lysates, suggesting that hyperphosphorylation of EBNA-2 impairs its affinity for PU.1. Finally, endogenous LMP-1 mRNA levels in M phase are around 55% of those in asynchronously growing cells. These results suggest that regulation of gene expression during type III latency may be regulated in a cell-cycle-related manner.

scholarly journals Differential Regulation of Epstein-Barr Virus (EBV) Latent Gene Expression in Burkitt Lymphoma Cells Infected with a Recombinant EBV Strain

2001 ◽  
Vol 75 (10) ◽  
pp. 4929-4935 ◽  
Author(s):  
Pankaj Trivedi ◽  
Paola Spinsanti ◽  
Laura Cuomo ◽  
Massimo Volpe ◽  
Kenzo Takada ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Differential Regulation ◽  
Type I ◽  
Phenotypic Differences ◽  
Barr Virus ◽  
Immune Pressure ◽  
Restricted Type ◽  
Promoter Usage ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV)-negative Burkitt lymphomas (BLs) can be infected in vitro with prototype EBV strains to study how the virus may affect the phenotype of tumor cells. Studies thus far have concentrated on the use of transforming B95-8 and nontransforming P3HR1 strains. Immunological and phenotypic differences between the sublines infected with these two strains were reported. The majority of these differences, if not all, can be attributed to the lack of EBNA-2 coding sequences in the P3HR1 strain. The recent development of a selectable Akata strain has opened up new possibilities for infecting epithelial and T cells as well. We infected five EBV-negative BL lines with the recombinant Akata virus. Our results indicate that the infected cell lines BL28, Ramos, and DG75 express EBNA-1, EBNA-2, and LMP1, the viral proteins associated with type III latency, and use both YUK and QUK splices. In contrast, two EBV-negative variants of Akata and Mutu when reinfected displayed restricted type I latency and expressed only EBNA-1. All clones of infected Mutu cells used the QUK splice exclusively. The usage of Qp was observed in a majority of Akata clones. Some Akata clones, however, were found to have double promoter usage (Qp and C/Wp) but at 4 months after infection did not express EBNA-2. The results demonstrate differential regulation of EBV latency in BLs with the same recombinant viral strain and suggest that the choice of latency type may be cell dependent. The restricted latency observed for infected Akata and Mutu cells indicates that a BL may opt for type I latency in the absence of immune pressure as well.

scholarly journals MicroRNA-155 Is an Epstein-Barr Virus-Induced Gene That Modulates Epstein-Barr Virus-Regulated Gene Expression Pathways

2008 ◽  
Vol 82 (11) ◽  
pp. 5295-5306 ◽  
Author(s):  
Qinyan Yin ◽  
Jane McBride ◽  
Claire Fewell ◽  
Michelle Lacey ◽  
Xia Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epstein Barr Virus ◽  
Type I ◽  
Type Iii ◽  
Barr Virus ◽  
Transcriptional Regulatory ◽  
Infected Cells ◽  
Epstein Barr ◽  
Regulated Gene Expression ◽  
In Cells

ABSTRACT The cellular microRNA miR-155 has been shown to be involved in lymphocyte activation and is expressed in Epstein-Barr virus (EBV)-infected cells displaying type III latency gene expression but not type I latency gene expression. We show here that the elevated levels of miR-155 in type III latency cells is due to EBV gene expression and not epigenetic differences in cell lines tested, and we show that expression in EBV-infected cells requires a conserved AP-1 element in the miR-155 promoter. Gene expression analysis was carried out in a type I latency cell line transduced with an miR-155-expressing retrovirus. This analysis identified both miR-155-suppressed and -induced cellular mRNAs and suggested that in addition to direct targeting of 3′ untranslated regions (UTRs), miR-155 alters gene expression in part through the alteration of signal transduction pathways. 3′ UTR reporter analysis of predicted miR-155 target genes identified the transcriptional regulatory genes encoding BACH1, ZIC3, HIVEP2, CEBPB, ZNF652, ARID2, and SMAD5 as miR-155 targets. Western blot analysis of the most highly suppressed of these, BACH1, showed lower expression in cells transduced with a miR-155 retrovirus. Inspection of the promoters from genes regulated in EBV-infected cells and in cells infected with an miR-155 retrovirus identified potential binding sequences for BACH1 and ZIC3. Together, these experiments suggest that the induction of miR-155 by EBV contributes to EBV-mediated signaling in part through the modulation of transcriptional regulatory factors.

scholarly journals Transcriptional Regulatory Properties of Epstein-Barr Virus Nuclear Antigen 3C Are Conserved in Simian Lymphocryptoviruses

2003 ◽  
Vol 77 (10) ◽  
pp. 5639-5648 ◽  
Author(s):  
Bo Zhao ◽  
Rozenn Dalbiès-Tran ◽  
Hua Jiang ◽  
Ingrid K. Ruf ◽  
Jeffery T. Sample ◽  
...  
Keyword(s):  
Nonhuman Primate ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Leucine Zipper ◽  
Nuclear Antigen ◽  
Homologous Proteins ◽  
Basic Leucine Zipper ◽  
Barr Virus ◽  
C Terminus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is a large transcriptional regulator essential for EBV-mediated immortalization of B lymphocytes. We previously identified interactions between EBNA-3C and two cellular transcription factors, Jκ and Spi proteins, through which EBNA-3C regulates transcription. To better understand the contribution of these interactions to EBNA-3C function and EBV latency, we examined whether they are conserved in the homologous proteins of nonhuman primate lymphocryptoviruses (LCVs), which bear a strong genetic and biological similarity to EBV. The homologue of EBNA-3C encoded by the LCV that infects baboons (BaLCV) was found to be only 35% identical in sequence to its EBV counterpart. Of particular significance, this homology localized predominantly to the N-terminal half of the molecule, which encompasses the domains in EBNA-3C that interact with Jκ and Spi proteins. Like EBNA-3C, both BaLCV and rhesus macaque LCV (RhLCV) 3C proteins bound to Jκ and repressed transcription mediated by EBNA-2 through its interaction with Jκ. Both nonhuman primate 3C proteins were also able to activate transcription mediated by the Spi proteins in the presence of EBNA-2. Like EBNA-3C, a domain encompassing the putative basic leucine zipper motif of the BaLCV-3C protein directly interacted with both Spi-1 and Spi-B. Surprisingly, a recently identified motif in EBNA-3C that mediates repression was not identifiable in the BaLCV-3C protein. Finally, although the C terminus of BaLCV-3C bears minimal homology to EBNA-3C, it nonetheless contains a C-terminal domain rich in glutamine and proline that was able to function as a potent transcriptional activation domain, as does the C terminus of EBNA-3C. The conservation of these functional motifs despite poor overall homology among the LCV 3C proteins strongly suggests that the interactions of EBNA-3C with Jκ and Spi do indeed play significant roles in the life cycle of EBV.

scholarly journals Interferon Regulatory Factor 7 Is Induced by Epstein-Barr Virus Latent Membrane Protein 1

2000 ◽  
Vol 74 (3) ◽  
pp. 1061-1068 ◽  
Author(s):  
Luwen Zhang ◽  
Joseph S. Pagano
Keyword(s):  
Membrane Protein ◽  
Epstein Barr Virus ◽  
Latent Membrane Protein ◽  
Negative Regulator ◽  
Latent Membrane Protein 1 ◽  
Type I ◽  
Regulatory Factor ◽  
Type Iii ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Infection by Epstein-Barr virus (EBV) generates several types of latency with different profiles of gene expression but with expression of Epstein-Barr nuclear antigen 1 (EBNA-1) in common. TheBamHI Q promoter (Qp) is used for the transcription of EBNA-1 mRNA in type I latency, which is an EBV infection state exemplified by Burkitt's lymphoma (BL). However, Qp is inactive in type III latency, and other promoters (C/Wp) are used for transcription of EBNA-1, which raises the question of how usage of these promoters is governed. Interferon (IFN) regulatory factor 7 (IRF-7) was identified first as a negative regulator of Qp. Expression of IRF-7 is associated with EBV type III latency, where Qp is inactive, but not with type I latency, raising the possibility that a viral gene product(s) expressed in type III latency might induce IRF-7 and repress Qp. Here, detailed analysis of the expression of IRF-7 revealed that it is associated with the expression of EBV latent membrane protein 1 (LMP-1) and that LMP-1 stimulates the expression of IRF-7 in type III latency in which Qp is inactive. In contrast, LMP-1 is not expressed in type I latency cells in which Qp is active. LMP-1 represses the constitutive activity of Qp reporter constructs. Mutational analysis of Qp reporter constructs revealed that the Qp IFN-stimulated response element (ISRE) is essential for the repression by LMP-1. Furthermore, LMP-1 reduced EBNA-1 mRNA derived from Qp only in type I cells in which IRF-7 could be induced. Finally, IFN-α, but not IFN-γ, repressed endogenous Qp activity, which is consistent with the ability of IFN-α to induce IRF-7. Thus, IRF-7 may mediate repression of Qp by LMP-1. The induction of IRF-7 by LMP-1 may be relevant to the silencing of Qp in EBV type III latency.

scholarly journals Dynamic Chromatin Boundaries Delineate a Latency Control Region of Epstein-Barr Virus

2004 ◽  
Vol 78 (22) ◽  
pp. 12308-12319 ◽  
Author(s):  
Charles M. Chau ◽  
Paul M. Lieberman
Keyword(s):  
Control Region ◽  
Epstein Barr Virus ◽  
Rna Polymerase Iii ◽  
Histone H3 ◽  
Type I ◽  
Transcription Control ◽  
Type Iii ◽  
Barr Virus ◽  
Chromatin Architecture ◽  
Epstein Barr

ABSTRACT The oncogenic potential of latent Epstein-Barr virus (EBV) can be regulated by epigenetic factors controlling LMP1 and EBNA2 gene transcription. The EBV latency control region (LCR) constitutes ∼12 kb of viral sequence spanning the divergent promoters of LMP1 and EBNA2 and encompasses the EBV latent replication origin OriP and RNA polymerase III-transcribed EBV-encoded RNA genes. We have used the chromatin immunoprecipitation assay to examine the chromatin architecture of the LCR in different types of EBV latency programs. We have found that histone H3 K4 methylation (H3mK4) was enriched throughout a large domain that extended from internal repeat 1 (IR1) to the terminal repeat in type III latency where EBNA2 and LMP1 genes are expressed. In type I latency where EBNA2 and LMP1 genes are transcriptionally silent, the H3mK4 domain contracts and does not enter the EBNA2 or LMP1 promoters. In contrast, histone H3 K9 methylation (H3mK9), associated with silent heterochromatin, was enriched in the EBNA2 and LMP1 upstream control regions in type I but not type III cells. MTA [5′-deoxy-5′(methylthio)adenosine], a pharmacological inhibitor of protein methylation, globally reduced histone H3mK4 and inhibited EBNA2 transcription in type III cells. 5′-Azacytidine, an inhibitor of DNA methylation that derepresses EBNA2 transcription in type I latency, caused H3mK4 expansion and a corresponding loss of H3mK9 at IR1. The chromatin boundary protein and transcription repressor CCCTC-binding factor was enriched at the EBNA2 transcription control region in type I but not type III cells. We also present evidence that OriP binding factors EBNA1 and ORC2 can interact with sequences outside of OriP including a region within IR1 that may influence EBNA2 transcription status. These results indicate that types I and III latency programs have distinct histone methylation patterns in the LCR and suggest that chromatin architecture coordinates gene expression of LMP1 and EBNA2.

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