scholarly journals The Epstein-Barr virus deubiquitinating enzyme BPLF1 regulates the activity of topoisomerase II during productive infection

2021 ◽  
Vol 17 (9) ◽  
pp. e1009954
Author(s):  
Jinlin Li ◽  
Noemi Nagy ◽  
Jiangnan Liu ◽  
Soham Gupta ◽  
Teresa Frisan ◽  
...  
Keyword(s):  
Cell Survival ◽  
Epstein Barr Virus ◽  
Topoisomerase Ii ◽  
Virus Production ◽  
Productive Infection ◽  
Dna Breaks ◽  
Barr Virus ◽  
Double Strand Dna Breaks ◽  
Proteolytic Pathway ◽  
Epstein Barr

Topoisomerases are essential for the replication of herpesviruses but the mechanisms by which the viruses hijack the cellular enzymes are largely unknown. We found that topoisomerase-II (TOP2) is a substrate of the Epstein-Barr virus (EBV) ubiquitin deconjugase BPLF1. BPLF1 co-immunoprecipitated and deubiquitinated TOP2, and stabilized SUMOylated TOP2 trapped in cleavage complexes (TOP2cc), which halted the DNA damage response to TOP2-induced double strand DNA breaks and promoted cell survival. Induction of the productive virus cycle in epithelial and lymphoid cell line carrying recombinant EBV encoding the active enzyme was accompanied by TOP2 deubiquitination, accumulation of TOP2ccs and resistance to Etoposide toxicity. The protective effect of BPLF1 was dependent on the expression of tyrosyl-DNA phosphodiesterase 2 (TDP2) that releases DNA-trapped TOP2 and promotes error-free DNA repair. These findings highlight a previously unrecognized function of BPLF1 in supporting a non-proteolytic pathway for TOP2cc debulking that favors cell survival and virus production.

scholarly journals The Epstein-Barr virus ubiquitin deconjugase BPLF1 regulates the activity of Topoisomerase II during virus replication

2021 ◽  
Author(s):  
JInlin Li ◽  
Noemi Nagy ◽  
Jiangnan Liu ◽  
Soham Gupta ◽  
Teresa Frisan ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Topoisomerase Ii ◽  
Virus Production ◽  
Lymphoblastoid Cell Lines ◽  
Barr Virus ◽  
Damage Response ◽  
Topoisomerase Poisons ◽  
Epstein Barr ◽  
Productive Virus

Topoisomerases are essential for the replication of herpesviruses but the mechanisms by which the viruses hijack the cellular enzymes are largely unknown. We found that topoisomerase-II (TOP2) is a substrate of the Epstein-Barr virus (EBV) ubiquitin deconjugase BPLF1. BPLF1 selectively inhibited the ubiquitination of TOP2 following treatment with topoisomerase poisons, interacted with TOP2a and TOP2b in co-immunoprecipitation and in vitro pull-down, stabilized Etoposide-trapped TOP2 cleavage complexes (TOP2cc), and promoted TOP2 SUMOylation, which halted the DNA-damage response and reduced Etoposide toxicity. Induction of the productive virus cycle promoted the accumulation of TOP2bcc, enhanced TOP2b SUMOylation, and reduced Etoposide toxicity in lymphoblastoid cell lines carrying recombinant EBV encoding the active enzyme. Attenuation of this phenotype upon expression of a catalytic mutant BPLF1-C61A impaired viral DNA synthesis and virus release. These findings highlight a previously unrecognized function of BPLF1 in promoting non-proteolytic pathways for TOP2cc debulking that favor cell survival and virus production.

scholarly journals Epstein-Barr Virus (EBV) Tegument Protein BGLF2 Promotes EBV Reactivation through Activation of the p38 Mitogen-Activated Protein Kinase

2015 ◽  
Vol 90 (2) ◽  
pp. 1129-1138 ◽  
Author(s):  
XueQiao Liu ◽  
Jeffrey I. Cohen
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
Epstein Barr Virus ◽  
Virus Production ◽  
Mitogen Activated Protein Kinase ◽  
Tegument Protein ◽  
Barr Virus ◽  
Ebv Reactivation ◽  
Mitogen Activated Protein ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus associated with both B cell and epithelial cell malignancies. EBV infection of B cells triggers activation of several signaling pathways that are critical for cell survival, virus latency, and growth transformation. To identify EBV proteins important for regulating cell signaling, we used a proteomic approach to screen viral proteins for AP-1 and NF-κB promoter activity in AP-1– and NF-κB–luciferase reporter assays. We found that EBV BGLF2 activated AP-1 but not NF-κB reporter activity. Expression of EBV BGLF2 in cells activated p38 and c-Jun N-terminal kinase (JNK), both of which are important for mitogen-activated protein kinase (MAPK) signaling. Deletion of the carboxyl-terminal 66 amino acids of BGLF2 reduced the ability of BGLF2 to activate JNK and p38. Expression of BGLF2 enhanced BZLF1 expression in latently EBV-infected lymphoblastoid cell lines, and knockdown of BGLF2 reduced EBV reactivation induced by IgG cross-linking. Expression of BGLF2 induced BZLF1 expression and virus production in EBV-infected gastric carcinoma cells. BGLF2 enhanced BZLF1 expression and EBV production by activating p38; chemical inhibition of p38 and MAPK/ERK kinases 1 and 2 (MEK1/2) reduced expression of BZLF1 and virus production induced by BGLF2. In summary, the EBV tegument protein BGLF2, which is delivered to the cell at the onset of virus infection, activates the AP-1 pathway and enhances EBV reactivation and virus production.IMPORTANCEEpstein-Barr virus (EBV) is associated with both B cell and epithelial cell malignancies, and the virus activates multiple signaling pathways important for its persistence in latently infected cells. We identified a viral tegument protein, BGLF2, which activates members of the mitogen-activated protein kinase signaling pathway. Expression of BGLF2 increased expression of EBV BZLF1, which activates a switch from latent to lytic virus infection, and increased production of EBV. Inhibition of BGFL2 expression or inhibition of p38/MAPK, which is activated by BGLF2, reduced virus reactivation from latency. These results indicate that a viral tegument protein which is delivered to cells upon infection activates signaling pathways to enhance virus production and facilitate virus reactivation from latency.

Interferon-γ Prevents Apoptosis in Epstein-Barr Virus-Infected Natural Killer Cell Leukemia in an Autocrine Fashion

Blood ◽  
1999 ◽  
Vol 93 (10) ◽  
pp. 3494-3504 ◽  
Author(s):  
Shin-ichi Mizuno ◽  
Koichi Akashi ◽  
Koichi Ohshima ◽  
Hiromi Iwasaki ◽  
Toshihiro Miyamoto ◽  
...  
Keyword(s):  
Natural Killer Cell ◽  
Cell Survival ◽  
Epstein Barr Virus ◽  
Killer Cell ◽  
Interferon Γ ◽  
Leukemia Cells ◽  
Cell Leukemia ◽  
Barr Virus ◽  
Ifn Γ ◽  
Epstein Barr

The significant function of cytokines includes maintenance of cell survival as well as induction of cell differentiation and/or proliferation. We demonstrate here that interferon-γ (IFN-γ) plays a role for progression of Epstein-Barr virus (EBV)-infected natural killer cell leukemia (NK leukemia) through maintaining cell survival. NK leukemia cells obtained from 7 patients had clonal episomal forms of EBV, indicating that the leukemic cells were of clonal origin. Although normal NK cells constitutively expressed Bcl-2, the EBV-infected NK leukemia cells lacked endogenous Bcl-2 expression and were hypersensitive to apoptosis in vitro. The addition of IFN-γ to the culture significantly inhibited their spontaneous apoptosis without inducing cell proliferation or upregulation of Bcl-2. The NK leukemia cells constitutively secreted IFN-γ, and the patients’ sera contained a high concentration of IFN-γ, levels that were high enough to prevent NK leukemia cells from apoptosis. Bcl-XL was not involved in the IFN-γ–induced NK leukemia cell survival. These data suggest that the acquisition of IFN-γ–mediated autocrine survival signals, other than Bcl-2 or BCL-XL, might be important for the development of EBV-infected NK leukemia.

scholarly journals The V-val subtype Epstein-Barr virus nuclear antigen 1 promotes cell survival after serum withdrawal

2014 ◽  
Vol 33 (2) ◽  
pp. 958-966 ◽  
Author(s):  
MEI CHAO ◽  
HSIAO-NING WANG ◽  
YI JIN LU ◽  
YU-SUN CHANG ◽  
JAU-SONG YU
Keyword(s):  
Cell Survival ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Serum Withdrawal ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals The Epstein-Barr Virus BMRF1 Protein Activates Transcription and Inhibits the DNA Damage Response by Binding NuRD

2019 ◽  
Vol 93 (22) ◽  
Author(s):  
Samuel G. Salamun ◽  
Justine Sitz ◽  
Carlos F. De La Cruz-Herrera ◽  
Jaime Yockteng-Melgar ◽  
Edyta Marcon ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nurd Complex ◽  
Dna Breaks ◽  
Nucleosome Remodeling ◽  
Barr Virus ◽  
Damage Response ◽  
Epstein Barr

ABSTRACT The BMRF1 protein of Epstein-Barr virus (EBV) has multiple roles in viral lytic infection, including serving as the DNA polymerase processivity factor, activating transcription from several EBV promoters and inhibiting the host DNA damage response to double-stranded DNA breaks (DSBs). Using affinity purification coupled to mass spectrometry, we identified the nucleosome remodeling and deacetylation (NuRD) complex as the top interactor of BMRF1. We further found that NuRD components localize with BMRF1 at viral replication compartments and that this interaction occurs through the BMRF1 C-terminal region previously shown to mediate transcriptional activation. We identified an RBBP4 binding motif within this region that can interact with both RBBP4 and MTA2 components of the NuRD complex and showed that point mutation of this motif abrogates NuRD binding as well as the ability of BMRF1 to activate transcription from the BDLF3 and BLLF1 EBV promoters. In addition to its role in transcriptional regulation, NuRD has been shown to contribute to DSB signaling in enabling recruitment of RNF168 ubiquitin ligase and subsequent ubiquitylation at the break. We showed that BMRF1 inhibited RNF168 recruitment and ubiquitylation at DSBs and that this inhibition was at least partly relieved by loss of the NuRD interaction. The results reveal a mechanism by which BMRF1 activates transcription and inhibits DSB signaling and a novel role for NuRD in transcriptional activation in EBV. IMPORTANCE The Epstein-Barr virus (EBV) BMRF1 protein is critical for EBV infection, playing key roles in viral genome replication, activation of EBV genes, and inhibition of host DNA damage responses (DDRs). Here we show that BMRF1 targets the cellular nucleosome remodeling and deacetylation (NuRD) complex, using a motif in the BMRF1 transcriptional activation sequence. Mutation of this motif disrupts the ability of BMRF1 to activate transcription and interfere with DDRs, showing the importance of the NuRD interaction for BMRF1 functions. BMRF1 was shown to act at the same step in the DDR as NuRD, suggesting that it interferes with NuRD function.

scholarly journals Epstein-Barr Virus mRNA Export Factor EB2 Is Essential for Production of Infectious Virus

2002 ◽  
Vol 76 (19) ◽  
pp. 9635-9644 ◽  
Author(s):  
Henri Gruffat ◽  
Julien Batisse ◽  
Dagmar Pich ◽  
Bernhard Neuhierl ◽  
Evelyne Manet ◽  
...  
Keyword(s):  
Dna Replication ◽  
Nuclear Export ◽  
Epstein Barr Virus ◽  
Alternative Pathway ◽  
Virus Production ◽  
Gene Encoding ◽  
Barr Virus ◽  
Cytoplasmic Accumulation ◽  
Epstein Barr ◽  
Simplex Virus

ABSTRACT The splicing machinery which positions a protein export complex near the exon-exon junction mediates nuclear export of mRNAs generated from intron-containing genes. Many Epstein-Barr virus (EBV) early and late genes are intronless, and an alternative pathway, independent of splicing, must export the corresponding mRNAs. Since the EBV EB2 protein induces the cytoplasmic accumulation of intronless mRNA, it is tempting to speculate that EB2 is a viral adapter involved in the export of intronless viral mRNA. If this is true, then the EB2 protein is essential for the production of EBV infectious virions. To test this hypothesis, we generated an EBV mutant in which the BMLF1 gene, encoding the EB2 protein, has been deleted (EBVBMLF1-KO). Our studies show that EB2 is necessary for the production of infectious EBV and that its function cannot be transcomplemented by a cellular factor. In the EBVBMLF1-KO 293 cells, oriLyt-dependent DNA replication was greatly enhanced by EB2. Accordingly, EB2 induced the cytoplasmic accumulation of a subset of EBV early mRNAs coding for essential proteins implicated in EBV DNA replication during the productive cycle. Two herpesvirus homologs of the EB2 protein, the herpes simplex virus type 1 protein ICP27 and, the human cytomegalovirus protein UL69, only partly rescued the phenotype of the EBVBMLF1-KO mutant, indicating that some EB2 functions in virus production cannot be transcomplemented by ICP27 and UL69.

scholarly journals Epstein-Barr Virus Small RNAs Potentiate Tumorigenicity of Burkitt Lymphoma Cells Independently of an Effect on Apoptosis

2000 ◽  
Vol 74 (21) ◽  
pp. 10223-10228 ◽  
Author(s):  
Ingrid K. Ruf ◽  
Paul W. Rhyne ◽  
Chunying Yang ◽  
John L. Cleveland ◽  
Jeffery T. Sample
Keyword(s):  
Cell Survival ◽  
Cell Line ◽  
Burkitt Lymphoma ◽  
Small Rnas ◽  
Epstein Barr Virus ◽  
Wild Type ◽  
Barr Virus ◽  
Tumorigenic Potential ◽  
Epstein Barr ◽  
Dependent Mechanism

ABSTRACT The tumorigenic potential of the Burkitt lymphoma (BL) cell line Akata is dependent on the restricted latency program of Epstein-Barr virus (EBV) that is characteristically maintained in BL tumors. Within these cells, EBV-mediated inhibition of apoptosis correlates with an up-regulation of BCL-2 levels in concert with a down-regulation in c-MYC expression that occurs under growth-limiting conditions. Here we addressed whether EBV's effects on apoptosis and tumorigenicity are mediated by the EBV small RNAs EBER-1 and EBER-2. Stable expression of the EBERs in EBV-negative Akata BL cells, at levels comparable to those in EBV-positive cells, significantly enhanced the tumorigenic potential of EBV-negative BL cells in SCID mice, but did not fully restore tumorigenicity relative to EBV-positive Akata cells. Furthermore, wild-type or greater levels of EBER expression in EBV-negative Akata cells did not promote BL cell survival. These data therefore suggest that EBV can contribute to BL through at least two avenues: an EBER-dependent mechanism that enhances tumorigenic potential independent of a direct effect on apoptosis, and a second mechanism, mediated by an as-yet-unidentified EBV gene(s), that offsets the proapoptotic consequences of deregulated c-MYC in BL.

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