scholarly journals Epstein-Barr virus inactivates the transcriptome and disrupts the chromatin architecture of its host cell in the first phase of lytic reactivation

2019 ◽  
Author(s):  
Alexander Buschle ◽  
Paulina Mrozek-Gorska ◽  
Stefan Krebs ◽  
Helmut Blum ◽  
Filippo M. Cernilogar ◽  
...  
Keyword(s):  
Host Cell ◽  
Epstein Barr Virus ◽  
De Novo ◽  
Human Tumor ◽  
Regulatory Elements ◽  
Lytic Cycle ◽  
Host Cells ◽  
Dependent Manner ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV), a herpes virus also termed HHV 4 and the first identified human tumor virus, establishes a stable long-term latent infection in human B cells, its preferred host. Upon induction of EBV’s lytic phase the latently infected cells turn into a virus factory, a process, that is governed by EBV. In the lytic, productive phase all herpesviruses ensure the efficient induction of all lytic viral genes to produce progeny, but certain of these genes also repress the ensuing antiviral responses of the virally infected host cells, regulate their apoptotic death or control the cellular transcriptome. We now find that EBV causes previously unknown massive and global alterations in the chromatin of its host cell upon induction of the viral lytic phase and prior to the onset of viral DNA replication. The viral initiator protein of the lytic cycle, BZLF1, binds to >105binding sites with different sequence motifs in cellular chromatin and in a concentration dependent manner. Concomitant with DNA binding, silent chromatin opens locally as shown by ATAC-seq experiments, while previously wide-open cellular chromatin becomes inaccessible on a global scale within hours. While viral transcripts increase drastically, the induction of the lytic phase results in a massive reduction of cellular transcripts and a loss of chromatin-chromatin interactions of cellular promoters with their distal regulatory elements as shown in Capture-C experiments. Our data document that EBV’s lytic cycle induces discrete early processes that disrupt the architecture of host cellular chromatin and repress the cellular epigenome and transcriptome likely supporting the efficientde novosynthesis of this herpesvirus.

scholarly journals The Late Lytic LMP-1 Protein of Epstein-Barr Virus Can Negatively Regulate LMP-1 Signaling

2000 ◽  
Vol 74 (2) ◽  
pp. 1057-1060 ◽  
Author(s):  
Kimberly D. Erickson ◽  
Jennifer M. Martin
Keyword(s):  
Epstein Barr Virus ◽  
Lytic Cycle ◽  
Dependent Manner ◽  
Reading Frame ◽  
Barr Virus ◽  
Tetradecanoyl Phorbol Acetate ◽  
Human B Cells ◽  
Negative Effect ◽  
Epstein Barr ◽  
Related Proteins

ABSTRACT The BNLF-1 open reading frame of Epstein-Barr virus (EBV) encodes two related proteins, latent membrane protein-1 (LMP-1) and lytic LMP-1 (lyLMP-1). LMP-1 is a latent protein required for immortalization of human B cells by EBV, whereas lyLMP-1 is expressed during the lytic cycle and is found in the EBV virion. We show here that, in contrast to LMP-1, lyLMP-1 is stable, with a half-life of >20 h in tetradecanoyl phorbol acetate- and butyrate-treated B95-8 cells. Although lyLMP-1 itself has negligible effects on NF-κB activity, it inhibits NF-κB activation by LMP-1 in a dose-dependent manner. The lyLMP-1 protein does not oligomerize with LMP-1, and the negative effect of lyLMP-1 on NF-κB activation by LMP-1 does not result from lyLMP-1-mediated disruption of LMP-1 oligomers. Modulation of LMP-1-activated signaling pathways is the first identified biological activity associated with lyLMP-1, and this activity may contribute to the progression of EBV's lytic cycle.

scholarly journals Epstein-Barr Virus MicroRNA miR-BART20-5p Suppresses Lytic Induction by InhibitingBAD-Mediatedcaspase-3-Dependent Apoptosis

2015 ◽  
Vol 90 (3) ◽  
pp. 1359-1368 ◽  
Author(s):  
Hyoji Kim ◽  
Hoyun Choi ◽  
Suk Kyeong Lee
Keyword(s):  
Epstein Barr Virus ◽  
Caspase 3 ◽  
Immune Surveillance ◽  
Virus Production ◽  
Lytic Cycle ◽  
Host Cells ◽  
Immediate Early ◽  
Progeny Virus ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV) is a human gammaherpesvirus associated with a variety of tumor types. EBV can establish latency or undergo lytic replication in host cells. In general, EBV remains latent in tumors and expresses a limited repertoire of latent proteins to avoid host immune surveillance. When the lytic cycle is triggered by some as-yet-unknown form of stimulation, lytic gene expression and progeny virus production commence. Thus far, the exact mechanism of EBV latency maintenance and thein vivotriggering signal for lytic induction have yet to be elucidated. Previously, we have shown that the EBV microRNA miR-BART20-5p directly targets the immediate early genesBRLF1andBZLF1as well asBcl-2-associated death promoter (BAD) in EBV-associated gastric carcinoma. In this study, we found that both mRNA and protein levels ofBRLF1andBZLF1were suppressed in cells followingBADknockdown and increased afterBADoverexpression. Progeny virus production was also downregulated by specific knockdown ofBAD. Our results demonstrated thatcaspase-3-dependent apoptosis is a prerequisite forBAD-mediated EBV lytic cycle induction. Therefore, our data suggest that miR-BART20-5p plays an important role in latency maintenance and tumor persistence of EBV-associated gastric carcinoma by inhibitingBAD-mediatedcaspase-3-dependent apoptosis, which would trigger immediate early gene expression.IMPORTANCEEBV has an ability to remain latent in host cells, including EBV-associated tumor cells hiding from immune surveillance. However, the exact molecular mechanisms of EBV latency maintenance remain poorly understood. Here, we demonstrated that miR-BART20-5p inhibited the expression of EBV immediate early genes indirectly, by suppressingBAD-inducedcaspase-3-dependent apoptosis, in addition to directly, as we previously reported. Our study suggests that EBV-associated tumor cells might endure apoptotic stress to some extent and remain latent with the aid of miR-BART20-5p. Blocking the expression or function of BART20-5p may expedite EBV-associated tumor cell death via immune attack and apoptosis.

scholarly journals Contribution of Epstein–Barr Virus Latent Proteins to the Pathogenesis of Classical Hodgkin Lymphoma

Pathogens ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 59 ◽  
Author(s):  
Katerina Vrzalikova ◽  
Taofik Sunmonu ◽  
Gary Reynolds ◽  
Paul Murray
Keyword(s):  
Host Cell ◽  
Hodgkin Lymphoma ◽  
Epstein Barr Virus ◽  
Host Cells ◽  
Classical Hodgkin Lymphoma ◽  
Cellular Functions ◽  
Human Virus ◽  
Barr Virus ◽  
Cell Functions ◽  
Epstein Barr

Pathogenic viruses have evolved to manipulate the host cell utilising a variety of strategies including expression of viral proteins to hijack or mimic the activity of cellular functions. DNA tumour viruses often establish latent infection in which no new virions are produced, characterized by the expression of a restricted repertoire of so-called latent viral genes. These latent genes serve to remodel cellular functions to ensure survival of the virus within host cells, often for the lifetime of the infected individual. However, under certain circumstances, virus infection may contribute to transformation of the host cell; this event is not a usual outcome of infection. Here, we review how the Epstein–Barr virus (EBV), the prototypic oncogenic human virus, modulates host cell functions, with a focus on the role of the EBV latent genes in classical Hodgkin lymphoma.

scholarly journals Upregulation of STAT3 Marks Burkitt Lymphoma Cells Refractory to Epstein-Barr Virus Lytic Cycle Induction by HDAC Inhibitors

2009 ◽  
Vol 84 (2) ◽  
pp. 993-1004 ◽  
Author(s):  
Derek Daigle ◽  
Cynthia Megyola ◽  
Ayman El-Guindy ◽  
Lyn Gradoville ◽  
David Tuck ◽  
...  
Keyword(s):  
Burkitt Lymphoma ◽  
Epstein Barr Virus ◽  
De Novo ◽  
Fundamental Problem ◽  
Single Cells ◽  
Lytic Cycle ◽  
Barr Virus ◽  
Refractory State ◽  
Epstein Barr

ABSTRACT A fundamental problem in studying the latent-to-lytic switch of Epstein-Barr virus (EBV) and the viral lytic cycle itself is the lack of a culture system fully permissive to lytic cycle induction. Strategies to target EBV-positive tumors by inducing the viral lytic cycle with chemical agents are hindered by inefficient responses to stimuli. In vitro, even in the most susceptible cell lines, more than 50% of cells latently infected with EBV are refractory to induction of the lytic cycle. The mechanisms underlying the refractory state are not understood. We separated lytic from refractory Burkitt lymphoma-derived HH514-16 cells after treatment with an HDAC inhibitor, sodium butyrate. Both refractory- and lytic-cell populations responded to the inducing stimulus by hyperacetylation of histone H3. However, analysis of host cell gene expression showed that specific cellular transcripts Stat3, Fos, and interleukin-8 (IL-8) were preferentially upregulated in the refractory-cell population, while IL-6 was upregulated in the lytic population. STAT3 protein levels were also substantially increased in refractory cells relative to untreated or lytic cells. This increase in de novo expression resulted primarily in unphosphorylated STAT3. Examination of single cells revealed that high levels of STAT3 were strongly associated with the refractory state. The refractory state is manifest in a unique subpopulation of cells that exhibits different cellular responses than do lytic cells exposed to the same stimulus. Identifying characteristics of cells refractory to lytic induction relative to cells that undergo lytic activation will be an important step in developing a better understanding of the regulation of the EBV latent to lytic switch.

Epstein-Barr virus lytic cycle activation alters proteasome subunit expression in Burkitt's lymphoma cells

2010 ◽  
Vol 391 (9) ◽  
Author(s):  
Alessandra De Leo ◽  
Giulia Matusali ◽  
Giuseppe Arena ◽  
Livia Di Renzo ◽  
Elena Mattia
Keyword(s):  
Epstein Barr Virus ◽  
Burkitt’S Lymphoma ◽  
Lytic Cycle ◽  
Host Cells ◽  
Burkitt's Lymphoma ◽  
Lymphoma Cells ◽  
Proteasome Subunit ◽  
Barr Virus ◽  
Subunit Expression ◽  
Epstein Barr

AbstractWe have shown that Epstein-Barr virus (EBV) lytic cycle activation in Burkitt's lymphoma (BL) cells down-regulates chymotrypsin- and caspase-like activities of the proteasome. The aim of the present study was to evaluate whether EBV activation might also affect proteasome subunit composition. Our results indicate that, independently of the latency program established in the host cells, induction of the EBV lytic cycle reduces the expression of the proteasomal components β5, β1 and β2i, whereas it increases that of β2, β1i, PA28α and PA28β. The modulation of the composition and enzymatic activities of the proteolytic complex are indicative of a less efficient generation of viral immunoepitopes.

scholarly journals Stimulus Duration and Response Time Independently Influence the Kinetics of Lytic Cycle Reactivation of Epstein-Barr Virus

2009 ◽  
Vol 83 (20) ◽  
pp. 10694-10709 ◽  
Author(s):  
Jill Countryman ◽  
Lyndle Gradoville ◽  
Sumita Bhaduri-McIntosh ◽  
Jianjiang Ye ◽  
Lee Heston ◽  
...  
Keyword(s):  
Response Time ◽  
Cell Lines ◽  
Stimulus Duration ◽  
Epstein Barr Virus ◽  
Histone Deacetylase Inhibitors ◽  
De Novo ◽  
Trichostatin A ◽  
Lytic Cycle ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) can be reactivated from latency into the lytic cycle by many stimuli believed to operate by different mechanisms. Cell lines containing EBV differ in their responses to inducing stimuli, yet all stimuli require de novo protein synthesis (44). A crucial step preliminary to identifying these proteins and determining when they are required is to measure the duration of stimulus and response time needed for activation of expression of EBV BRLF1 and BZLF1, the earliest viral indicators of reactivation. Here we show, with four EBV-containing cell lines that respond to different inducing agents, that stimuli that are effective at reactivating EBV can be divided into two main groups. The histone deacetylase inhibitors sodium butyrate and trichostatin A require a relatively long period of exposure, from 2 to 4 h or longer. Phorbol esters, anti-immunoglobulin G (anti-IgG), and, surprisingly, 5-aza-2′-deoxycytidine require short exposures of 15 min or less. The cell/virus background influences the response time. Expression of the EBV BZLF1 and BRLF1 genes can be detected before 2 h in Akata cells treated with anti-IgG, but both long- and short-duration stimuli required 4 or more hr to activate BZLF1 and BRLF1 expression in HH514-16, Raji, or B95-8 cells. Thus, stimulus duration and response time are independent variables. Neither stimulus duration nor response time can be predicted by the number of cells activated into the lytic cycle. These experiments shed new light on the earliest events leading to lytic cycle reactivation of EBV.

scholarly journals Promoter-Proximal Regulatory Elements Involved in oriP-EBNA1-Independent and -Dependent Activation of the Epstein-Barr Virus C Promoter in B-Lymphoid Cell Lines

2001 ◽  
Vol 75 (13) ◽  
pp. 5796-5811 ◽  
Author(s):  
Tina Nilsson ◽  
Henrik Zetterberg ◽  
Yuyan Camilla Wang ◽  
Lars Rymo
Keyword(s):  
Transcription Factor ◽  
Epstein Barr Virus ◽  
Regulatory Elements ◽  
Negative Regulator ◽  
Regulatory Sequences ◽  
Barr Virus ◽  
Group I ◽  
Epstein Barr ◽  
B Lymphoid ◽  
Virus C

ABSTRACT The identification of the cellular factors that control the transcription regulatory activity of the Epstein-Barr virus C promoter (Cp) is fundamental to the understanding of the molecular mechanisms that control virus latent gene expression. Using transient transfection of reporter plasmids in group I phenotype B-lymphoid cells, we have previously shown that the −248 to −55 region (−248/−55 region) of Cp contains elements that are essential fororiPI-EBNA1-dependent as well asoriPI-EBNA1-independent activation of the promoter. We now establish the importance of this region by a detailed mutational analysis of reporter plasmids carrying Cp regulatory sequences together with or without oriPI. The reporter plasmids were transfected into group I phenotype Rael cells and group III phenotype cbc-Rael cells, and the Cp activity measured was correlated with the binding of candidate transcription factors in electrophoretic mobility shift assays and further assessed in cotransfection experiments. We show that the NF-Y transcription factor interacts with the previously identified CCAAT box in the −71/−63 Cp region (M. T. Puglielli, M. Woisetschlaeger, and S. H. Speck, J. Virol. 70:5758–5768, 1996). We also show that members of the C/EBP transcription factor family interact with a C/EBP consensus sequence in the −119/−112 region of Cp and that this interaction is important for promoter activity. A central finding is the identification of a GC-rich sequence in the −99/−91 Cp region that is essential fororiPI-EBNA1-independent as well asoriPI-EBNA1-dependent activity of the promoter. This region contains overlapping binding sites for Sp1 and Egr-1, and our results suggest that Sp1 is a positive and Egr-1 is a negative regulator of Cp activity. Furthermore, we demonstrate that a reporter plasmid that in addition to oriPI contains only the −111/+76 region of Cp still retains the ability to be activated by EBNA1.

DNA-binding-defective mutants of the Epstein-Barr virus lytic switch activator Zta transactivate with altered specificities

1994 ◽  
Vol 14 (5) ◽  
pp. 3041-3052
Author(s):  
E K Flemington ◽  
J P Lytle ◽  
C Cayrol ◽  
A M Borras ◽  
S H Speck
Keyword(s):  
Dna Binding ◽  
Epstein Barr Virus ◽  
Lytic Cycle ◽  
Promoter Elements ◽  
Barr Virus ◽  
Binding Forms ◽  
Viral Genes ◽  
Direct Binding ◽  
Epstein Barr ◽  
Necessary And Sufficient

The Epstein-Barr virus BRLF1 and BZLF1 genes are the first viral genes transcribed upon induction of the viral lytic cycle. The protein products of both genes (referred to here as Rta and Zta, respectively) activate expression of other viral genes, thereby initiating the lytic cascade. Among the viral antigens expressed upon induction of the lytic cycle, however, Zta is unique in its ability to disrupt viral latency; expression of the BZLF1 gene is both necessary and sufficient for triggering the viral lytic cascade. We have previously shown that Zta can activate its own promoter (Zp), through binding to two Zta recognition sequences (ZIIIA and ZIIIB). Here we describe mutant Zta proteins that do not bind DNA (referred to as Zta DNA-binding mutants [Zdbm]) but retain the ability to transactivate Zp. Consistent with the inability of these mutants to bind DNA, transactivation of Zp by Zdbm is not dependent on the Zta recognition sequences. Instead, transactivation by Zdbm is dependent upon promoter elements that bind cellular factors. An examination of other viral and cellular promoters identified promoters that are weakly responsive or unresponsive to Zdbm. An analysis of a panel of artificial promoters containing one copy of various promoter elements demonstrated a specificity for Zdbm activation that is distinct from that of Zta. These results suggest that non-DNA-binding forms of some transactivators retain the ability to transactivate specific target promoters without direct binding to DNA.

Sign in / Sign up

Export Citation Format

Share Document