Suppression of JAK-STAT signaling by Epstein-Barr virus tegument protein BGLF2 through recruitment of SHP1 phosphatase and promotion of STAT2 degradation

2021 ◽  
Author(s):  
Sonia Jangra ◽  
Aradhana Bharti ◽  
Wai-Yin Lui ◽  
Vidyanath Chaudhary ◽  
Michael George Botelho ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Suppressive Effect ◽  
Host Cells ◽  
Interferon Response ◽  
Tegument Protein ◽  
Type Ii ◽  
Barr Virus ◽  
Stat Signaling ◽  
Epstein Barr ◽  
Type Iii Ifn

Some lytic proteins encoded by Epstein-Barr virus (EBV) suppress host interferon (IFN) signaling to facilitate viral replication. In this study we sought to identify and characterize EBV proteins antagonizing IFN signaling. The induction of IFN-stimulated genes (ISGs) by IFN-β was effectively suppressed by EBV. A functional screen was therefore performed to identify IFN-antagonizing proteins encoded by EBV. EBV tegument protein BGLF2 was identified as a potent suppressor of JAK-STAT signaling. This activity was found to be independent of its stimulatory effect on p38 and JNK pathways. Association of BGLF2 with STAT2 resulted in more pronounced K48-linked polyubiquitination and proteasomal degradation of the latter. Mechanistically, BGLF2 promoted the recruitment of SHP1 phosphatase to STAT1 to inhibit its tyrosine phosphorylation. In addition, BGLF2 associated with cullin 1 E3 ubiquitin ligase to facilitate its recruitment to STAT2. Consequently, BGLF2 suppressed ISG induction by IFN-β. Furthermore, BGLF2 also suppressed type II and type III IFN signaling, although the suppressive effect on type II IFN response was milder. When pre-treated with IFN-β, host cells became less susceptible to primary infection of EBV. This phenotype was reversed when expression of BGLF2 was enforced. Finally, genetic disruption of BGLF2 in EBV led to more pronounced induction of ISGs. Taken together, our study unveils the roles of BGLF2 not only in the subversion of innate IFN response but also in lytic infection and reactivation of EBV. Importance Epstein-Barr virus (EBV) is an oncogenic virus associated with the development of lymphoid and epithelial malignancies. EBV has to subvert interferon-mediated host antiviral response to replicate and cause diseases. It is therefore of great interest to identify and characterize interferon-antagonizing proteins produced by EBV. In this study we perform a screen to search for EBV proteins that suppress the action of interferons. We further show that BGLF2 protein of EBV is particularly strong in this suppression. This is achieved by inhibiting two key proteins STAT1 and STAT2 that mediate the antiviral activity of interferons. BGLF2 recruits a host enzyme to remove the phosphate group from STAT1 thereby inactivating its activity. BGLF2 also redirects STAT2 for degradation. A recombinant virus in which BGLF2 gene has been disrupted can activate host interferon response more robustly. Our findings reveal a novel mechanism by which EBV BGLF2 protein suppresses interferon signaling.

scholarly journals Interferon Antagonism of Epstein–Barr Virus Tegument Proteins

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 74
Author(s):  
Wai-Yan Lui ◽  
Sonia Jangra ◽  
Kit-San Yuen ◽  
Michael George Botelho ◽  
Dong-Yan Jin
Keyword(s):  
Epstein Barr Virus ◽  
Tyrosine Phosphatase ◽  
Host Cells ◽  
Tegument Protein ◽  
Small Subset ◽  
Type I ◽  
Type I Ifn ◽  
Tegument Proteins ◽  
Barr Virus ◽  
Epstein Barr

The Epstein–Barr virus (EBV) successfully infects 95% of all adults but causes Burkitt’s lymphoma, Hodgkin’s lymphoma, gastric carcinoma, nasopharyngeal carcinoma or other malignancies in only a small subset of infected individuals. The virus must have developed effective viral countermeasures to evade host innate immunity. In this study, we performed functional screens to identify EBV-encoded interferon (IFN) antagonists. Several tegument proteins were found to be potent suppressors of IFN production and/or signaling. The large tegument protein and deubiquitinase BPLF1 antagonized type I IFN production induced by DNA sensors cGAS and STING or RNA sensors RIG-I and MAVS. BPLF1’s ability to suppress innate immune signaling required its deubiquitinase activity. BPLF1 functioned as a catalytically active deubiquitinase for both K63- and K48-linked ubiquitin chains on STING and TBK1, with no ubiquitin linkage specificity. Induced expression of BPLF1 in EBV-infected cells through CRISPRa led to effective suppression of innate DNA and RNA sensing. Another EBV tegument protein, BGLF2, was found to suppress JAK-STAT signaling. This suppression was ascribed to more pronounced K48-linked polyubiquitination and proteasomal degradation of BGLF2-associated STAT2. In addition, BGLF2 also recruited tyrosine phosphatase SHP1 to inhibit tyrosine phosphorylation of JAK1 and STAT1. A BGLF2-deficient EBV activated type I IFN signaling more robustly. Taken together, we characterized the IFN antagonism of EBV tegument proteins BPLF1 and BGLF2, which modulate ubiquitination of key transducer proteins to counteract type I IFN production and signaling in host cells. Supported by HMRF 17160822, HMRF 18170942, and RGC C7027-16G.

scholarly journals Epstein-Barr virus tegument protein BGLF2 in exosomes released from virus-producer cells assists de novo infection by enhancing viral gene expression

2020 ◽  
Author(s):  
Masahiro Yaguchi ◽  
Yoshitaka Sato ◽  
Yusuke Okuno ◽  
Takayuki Murata ◽  
Somi Ozaki ◽  
...  
Keyword(s):  
Viral Infection ◽  
Epstein Barr Virus ◽  
Host Cells ◽  
Tegument Protein ◽  
Tegument Proteins ◽  
Barr Virus ◽  
Ebv Infection ◽  
Cellular Environment ◽  
Infected Cells ◽  
Epstein Barr

AbstractViruses must adapt to the environment of their host cells to establish infection and persist. Diverse mammalian cells, including virus-infected cells, secrete extracellular vesicles such as exosomes containing proteins and miRNAs. These vesicles mediate intercellular communications, suggesting that they modulate viral infection by adapting cellular conditions. However, the roles of exosomes in viral infection remain unclear. Here we screened viral proteins to identify those responsible for the exosome-mediated upregulation of Epstein-Barr virus (EBV) infection. We found BGLF2 protein encapsulated in exosomes, which enhanced the EBV infection of Akata(-) B-cells. BGLF2 protein is a tegument protein that lines the space between the envelope and the nucleocapsid, and it is released shortly after infection into the cytoplasm. Therefore, tegument protein BGLF2 is encapsulated not only in viral particles, but also in exosomes secreted from infected cells, and plays crucial roles in establishing the EBV latent infection by modulating the cellular environment.ImportanceTegument proteins that line the space between the envelope and nucleocapsid are released shortly after infection into the cytoplasm to modulate the cellular environment. In this study, we identified that tegument protein BGLF2, which is conserved in all herpesviruses, is incorporated into exosomes and transferred to neighboring cells. Exosomes containing BGLF2 enhanced the infectivity of EBV. These findings suggest that this and perhaps other tegument proteins support viral infection not only between the envelope and nucleocapsid, but also in extra-virus particles such as exosomes.

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.

scholarly journals Identification of Three gp350/220 Regions Involved in Epstein-Barr Virus Invasion of Host Cells

2005 ◽  
Vol 280 (42) ◽  
pp. 35598-35605 ◽  
Author(s):  
Mauricio Urquiza ◽  
Ramses Lopez ◽  
Helena Patiño ◽  
Jaiver E. Rosas ◽  
Manuel E. Patarroyo
Keyword(s):  
Epstein Barr Virus ◽  
Host Cells ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Elucidation of the c-Jun N-Terminal Kinase Pathway Mediated by Epstein-Barr Virus-Encoded Latent Membrane Protein 1

2004 ◽  
Vol 24 (1) ◽  
pp. 192-199 ◽  
Author(s):  
Jun Wan ◽  
Luguo Sun ◽  
Jennifer Woo Mendoza ◽  
Yiu Loon Chui ◽  
Dolly P. Huang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Epstein Barr Virus ◽  
Cellular Transformation ◽  
Latent Membrane Protein ◽  
Host Cells ◽  
Latent Membrane Protein 1 ◽  
Tnf Receptor ◽  
Jnk Pathway ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) is associated with several human diseases including infectious mononucleosis and nasopharyngeal carcinoma. EBV-encoded latent membrane protein 1 (LMP1) is oncogenic and indispensable for cellular transformation caused by EBV. Expression of LMP1 in host cells constitutively activates both the c-Jun N-terminal kinase (JNK) and NF-κB pathways, which contributes to the oncogenic effect of LMP1. However, the underlying signaling mechanisms are not very well understood. Based mainly on overexpression studies with various dominant-negative constructs, LMP1 was generally thought to functionally mimic members of the tumor necrosis factor (TNF) receptor superfamily in signaling. In contrast to the prevailing paradigm, using embryonic fibroblasts from different knockout mice and the small interfering RNA technique, we find that the LMP1-mediated JNK pathway is distinct from those mediated by either TNF-α or interleukin-1. Moreover, we have further elucidated the LMP1-mediated JNK pathway by demonstrating that LMP1 selectively utilizes TNF receptor-associated factor 6, TAK1/TAB1, and c-Jun N-terminal kinase kinases 1 and 2 to activate JNK.

IFN-α–Stimulated Genes and Epstein-Barr Virus Gene Expression Distinguish WHO Type II and III Nasopharyngeal Carcinomas

2007 ◽  
Vol 67 (2) ◽  
pp. 474-481 ◽  
Author(s):  
D. Michiel Pegtel ◽  
Aravind Subramanian ◽  
David Meritt ◽  
Ching-Hwa Tsai ◽  
Tzung-Shiahn Sheen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epstein Barr Virus ◽  
Type Ii ◽  
Virus Gene ◽  
Barr Virus ◽  
Virus Gene Expression ◽  
Epstein Barr

scholarly journals Activation of TRAF5 and TRAF6 Signal Cascades Negatively Regulates the Latent Replication Origin of Epstein-Barr Virus through p38 Mitogen-Activated Protein Kinase

2001 ◽  
Vol 75 (11) ◽  
pp. 5059-5068 ◽  
Author(s):  
Masaki Shirakata ◽  
Ken-Ichi Imadome ◽  
Kenji Okazaki ◽  
Kanji Hirai
Keyword(s):  
P38 Mapk ◽  
Replication Origin ◽  
Epstein Barr Virus ◽  
Suppressive Effect ◽  
Dominant Negative ◽  
Barr Virus ◽  
Extracellular Signals ◽  
Signal Cascade ◽  
Epstein Barr ◽  
Signal Cascades

ABSTRACT Latent Epstein-Barr virus (EBV) is maintained by the virus replication origin oriP that initiates DNA replication with the viral oriP-binding factor EBNA1. However, it is not known whether oriP's replicator activity is regulated by virus proteins or extracellular signals. By using a transient replication assay, we found that a low level of expression of viral signal transduction activator latent membrane protein 1 (LMP1) suppressed oriP activity. The binding site of the tumor necrosis factor receptor-associated factor (TRAF) of LMP1 was essential for this suppressive effect. Activation of the TRAF signal cascade by overexpression of TRAF5 and/or TRAF6 also suppressed oriPactivity. Conversely, blocking of TRAF signaling with dominant negative mutants of TRAF5 and TRAF6, as well as inhibition of a downstream signal mediator p38 MAPK, released the LMP1-inducedoriP suppression. Furthermore, activation of TRAF6 signal cascade by lipopolysaccharides (LPS) resulted in loss of EBV from Burkitt's lymphoma cell line Akata, and inhibition of p38 MAPK abolished the suppressive effect of LPS. These results suggested that the level of oriP activity is regulated by LMP1 and extracellular signals through TRAF5- and TRAF6-mediated signal cascades.

scholarly journals Modulation of Epstein-Barr Virus Glycoprotein B (gB) Fusion Activity by the gB Cytoplasmic Tail Domain

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicholas J. Garcia ◽  
Jia Chen ◽  
Richard Longnecker
Keyword(s):  
Membrane Fusion ◽  
Epstein Barr Virus ◽  
Cytoplasmic Tail ◽  
Host Cells ◽  
Glycoprotein B ◽  
Tail Domain ◽  
Induced Membrane ◽  
Barr Virus ◽  
Cellular Expression ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV), along with other members of the herpesvirus family, requires a set of viral glycoproteins to mediate host cell attachment and entry. Viral glycoprotein B (gB), a highly conserved glycoprotein within the herpesvirus family, is thought to be the viral fusogen based on structural comparison of EBV gB and herpes simplex virus (HSV) gB with the postfusion crystal structure of vesicular stomatitis virus fusion protein glycoprotein G (VSV-G). In addition, mutational studies indicate that gB plays an important role in fusion function. In the current study, we constructed a comprehensive library of mutants with truncations of the C-terminal cytoplasmic tail domain (CTD) of EBV gB. Our studies indicate that the gB CTD is important in the cellular localization, expression, and fusion function of EBV gB. However, in line with observations from other studies, we conclude that the degree of cell surface expression of gB is not directly proportional to observed fusion phenotypes. Rather, we conclude that other biochemical or biophysical properties of EBV gB must be altered to explain the different fusion phenotypes observed.IMPORTANCEEpstein-Barr virus (EBV), like all enveloped viruses, fuses the virion envelope to a cellular membrane to allow release of the capsid, resulting in virus infection. To further characterize the function of EBV glycoprotein B (gB) in fusion, a comprehensive library of mutants with truncations in the gB C-terminal cytoplasmic tail domain (CTD) were made. These studies indicate that the CTD of gB is important for the cellular expression and localization of gB, as well as for the function of gB in fusion. These studies will lead to a better understanding of the mechanism of EBV-induced membrane fusion and herpesvirus-induced membrane fusion in general, which will ultimately lead to focused therapies guided at preventing viral entry into host cells.

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