Repression of interferon regulatory factor 3 by the Epstein-Barr virus immediate-early protein Rta is mediated through E2F1 in HeLa cells

ABSTRACT Virus infection stimulates potent antiviral responses; specifically, Epstein-Barr virus (EBV) infection induces and activates interferon regulatory factor 7 (IRF-7), which is essential for production of alpha/beta interferons (IFN-α/β) and upregulates expression of Tap-2. Here we present evidence that during cytolytic viral replication the immediate-early EBV protein BZLF-1 counteracts effects of IRF-7 that are central to host antiviral responses. We initiated these studies by examining IRF-7 protein expression in vivo in lesions of hairy leukoplakia (HLP) in which there is abundant EBV replication but the expected inflammatory infiltrate is absent. This absence might predict that factors involved in the antiviral response are absent or inactive. First, we detected significant levels of IRF-7 in the nucleus, as well as in the cytoplasm, of cells in HLP lesions. IRF-7 activity in cell lines during cytolytic viral replication was examined by assay of the IRF-7-responsive promoters, IFN-α4, IFN-β, and Tap-2, as well as of an IFN-stimulated response element (ISRE)-containing reporter construct. These reporter constructs showed consistent reduction of activity during lytic replication. Both endogenous and transiently expressed IRF-7 and EBV BZLF-1 proteins physically associate in cell culture, although BZLF-1 had no effect on the nuclear localization of IRF-7. However, IRF-7-dependent activity of the IFN-α4, IFN-β, and Tap-2 promoters, as well as an ISRE promoter construct, was inhibited by BZLF-1. This inhibition occurred in the absence of other EBV proteins and was independent of IFN signaling. Expression of BZLF-1 also inhibited activation of IRF-7 by double-stranded RNA, as well as the activity of a constitutively active mutant form of IRF-7. Negative regulation of IRF-7 by BZLF-1 required the activation domain but not the DNA-binding domain of BZLF-1. Thus, EBV may subvert cellular antiviral responses and immune detection by blocking the activation of IFN-α4, IFN-β, and Tap-2 by IRF-7 through the medium of BZLF-1 as a negative regulator.

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The B-Cell Specific Transcription Factor, Oct-2, Promotes Epstein-Barr Virus Latency by Inhibiting the Viral Immediate-Early Protein, BZLF1

PLoS Pathogens ◽

10.1371/journal.ppat.1002516 ◽

2012 ◽

Vol 8 (2) ◽

pp. e1002516 ◽

Cited By ~ 29

Author(s):

Amanda R. Robinson ◽

Swee Sen Kwek ◽

Shannon C. Kenney

Keyword(s):

Transcription Factor ◽

B Cell ◽

Epstein Barr Virus ◽

Immediate Early ◽

Specific Transcription Factor ◽

Barr Virus ◽

Virus Latency ◽

Early Protein ◽

Epstein Barr

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Epstein-Barr Virus Immediate-Early Proteins BZLF1 and BRLF1 Activate the ATF2 Transcription Factor by Increasing the Levels of Phosphorylated p38 and c-Jun N-Terminal Kinases

Journal of Virology ◽

10.1128/jvi.74.3.1224-1233.2000 ◽

2000 ◽

Vol 74 (3) ◽

pp. 1224-1233 ◽

Cited By ~ 130

Author(s):

Amy L. Adamson ◽

Dayle Darr ◽

Elizabeth Holley-Guthrie ◽

Robert A. Johnson ◽

Amy Mauser ◽

...

Keyword(s):

Transcription Factor ◽

Epstein Barr Virus ◽

Viral Latency ◽

Immediate Early ◽

Expression Vectors ◽

Protein Z ◽

Barr Virus ◽

Ebv Infection ◽

Early Protein ◽

Epstein Barr

ABSTRACT Expression of either Epstein-Barr virus (EBV) immediate-early protein BZLF1 (Z) or BRLF1 (R) is sufficient to convert EBV infection from the latent to lytic form. Disruption of viral latency requires transcriptional activation of the Z and R promoters. The Z and R proteins are transcriptional activators, and each immediate-early protein activates expression of the other immediate-early protein. Z activates the R promoter through a direct binding mechanism. However, R does not bind directly to the Z promoter. In this study, we demonstrate that the ZII element (a cyclic AMP response element site) in the Z promoter is required for efficient activation by R. The ZII element has been shown to be important for induction of lytic EBV infection by tetradecanoyl phorbol acetate and surface immunoglobulin cross-linking and is activated by Z through an indirect mechanism. We demonstrate that both R and Z activate the cellular stress mitogen-activated protein (MAP) kinases, p38 and JNK, resulting in phosphorylation (and activation) of the cellular transcription factor ATF2. Furthermore, we show that the ability of R to induce lytic EBV infection in latently infected cells is significantly reduced by inhibition of either the p38 kinase or JNK pathways. In contrast, inhibition of stress MAP kinase pathways does not impair the ability of Z expression vectors to disrupt viral latency, presumably because expression of Z under the control of a strong heterologous promoter bypasses the need to activate Z transcription. Thus, both R and Z can activate the Z promoter indirectly by inducing ATF2 phosphorylation, and this activity appears to be important for R-induced disruption of viral latency.

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Interferon Regulatory Factor 7 Is Associated with Epstein-Barr Virus-Transformed Central Nervous System Lymphoma and Has Oncogenic Properties

Journal of Virology ◽

10.1128/jvi.78.23.12987-12995.2004 ◽

2004 ◽

Vol 78 (23) ◽

pp. 12987-12995 ◽

Cited By ~ 44

Author(s):

Luwen Zhang ◽

Jun Zhang ◽

Que Lambert ◽

Channing J. Der ◽

Luis Del Valle ◽

...

Keyword(s):

Central Nervous System ◽

Epstein Barr Virus ◽

Interferon Regulatory Factor ◽

Regulatory Factor ◽

3T3 Cells ◽

Barr Virus ◽

Interferon Regulatory Factor 7 ◽

Epstein Barr ◽

Nih 3T3 ◽

Nih 3T3 Cells

ABSTRACT Interferon regulatory factor 7 (IRF-7) is implicated in the regulation of Epstein-Barr virus (EBV) latency. EBV transforms primary B cells, and the major EBV oncoprotein, latent membrane protein 1 (LMP-1), is required for the process. LMP-1 both induces the expression of IRF-7 and activates the IRF-7 protein by phosphorylation and nuclear translocation. Here we report that the expression of IRF-7 is increased in EBV-immortalized B lymphocytes compared with that in primary B cells. IRF-7 was phosphorylated and predominantly localized in the nucleus in the immortalized cells. The expression of IRF-7 was detected in 19 of 27 specimens of primary lymphomas of the human central nervous system by immunohistochemical analysis. The association between LMP-1 and IRF-7 was statistically highly significant for these specimens. An appreciable amount of the IRF-7 expressed in lymphoma cells was localized in the nucleus. Furthermore, IRF-7 promoted the anchorage-independent growth of NIH 3T3 cells. LMP-1 and IRF-7 showed additive effects on the growth transformation of NIH 3T3 cells. IRF-7-expressing NIH 3T3 cells formed tumors in athymic mice. Thus, IRF-7 has oncogenic properties and, along with LMP-1, may mediate or potentiate the EBV transformation process in the pathogenesis of EBV-associated lymphomas.

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Interferon Regulatory Factor 5 Represses Expression of the Epstein-Barr Virus Oncoprotein LMP1: Braking of the IRF7/LMP1 Regulatory Circuit

Journal of Virology ◽

10.1128/jvi.79.18.11671-11676.2005 ◽

2005 ◽

Vol 79 (18) ◽

pp. 11671-11676 ◽

Cited By ~ 33

Author(s):

Shunbin Ning ◽

Leslie E. Huye ◽

Joseph S. Pagano

Keyword(s):

Transient Expression ◽

Epstein Barr Virus ◽

Interferon Regulatory Factor ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Dependent Manner ◽

Regulatory Factor ◽

Barr Virus ◽

Regulatory Circuit ◽

Epstein Barr

ABSTRACT We have reported evidence for a positive regulatory circuit between interferon regulatory factor 7 (IRF7) and the Epstein-Barr virus (EBV) oncoprotein 1 (LMP1) (S. Ning, A. M. Hahn, and J. S. Pagano, J. Virol. 77:9359-9368, 2003). To explore a possible braking mechanism for this circuit, several type II EBV-infected cell lines that express different levels of LMP1 and IRF7 proteins and therefore are convenient for studying modulation of expression of LMP1 were analyzed. Endogenous levels of IRF7 and LMP1 were directly correlated. Transient expression of an IRF7 dominant-negative mutant decreased LMP1 levels. Endogenous IRF5 and IRF7 proteins were shown to physically associate in EBV-positive cells. Transient expression of IRF5 decreased activation of the LMP1 promoter by IRF7 in a dose-dependent manner. Finally, transfection of either an IRF5 dominant-negative construct or IRF5 small interfering RNA in these cells resulted in increases in endogenous levels of LMP1. These results indicate that IRF5 can downregulate IRF7's induction of expression of LMP1 most likely by interacting with IRF7 and provide a means of modulating a regulatory circuit between IRF7 and LMP1.

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Interferon regulatory factor 7 is involved in the growth of Epstein–Barr virus-transformed human B lymphocytes

Virus Research ◽

10.1016/j.virusres.2014.09.005 ◽

2015 ◽

Vol 195 ◽

pp. 112-118 ◽

Cited By ~ 3

Author(s):

Dongsheng Xu ◽

Yanyan Zhang ◽

Lingjun Zhao ◽

Mingxia Cao ◽

Amy Lingel ◽

...

Keyword(s):

B Lymphocytes ◽

Epstein Barr Virus ◽

Interferon Regulatory Factor ◽

Regulatory Factor ◽

Barr Virus ◽

Interferon Regulatory Factor 7 ◽

Epstein Barr

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The viral interferon-regulatory factor-3 is required for the survival of KSHV-infected primary effusion lymphoma cells

Blood ◽

10.1182/blood-2007-05-092288 ◽

2008 ◽

Vol 111 (1) ◽

pp. 320-327 ◽

Cited By ~ 73

Author(s):

Effi Wies ◽

Yasuko Mori ◽

Alexander Hahn ◽

Elisabeth Kremmer ◽

Michael Stürzl ◽

...

Keyword(s):

Primary Effusion Lymphoma ◽

Human Herpesvirus ◽

Kaposi Sarcoma ◽

Interferon Regulatory Factor ◽

Regulatory Factor ◽

Interferon Regulatory Factor 3 ◽

Knock Down ◽

Barr Virus ◽

Caspase 7 ◽

Epstein Barr

Human herpesvirus-8 (HHV-8), also known as Kaposi sarcoma–associated herpesvirus (KSHV), is etiologically linked to primary effusion lymphoma (PEL). At least 10 KSHV-encoded proteins with potential roles in KSHV-associated neoplasia have been identified. However, with few exceptions, these putative oncogenes were analyzed in heterologous systems only using overexpression of single genes. Thus, the pathogenetic relevance of most of these putative oncogenes remains essentially unclear. We used RNA interference (RNAi) to knock down the expression of several KSHV genes in cultured PEL cells carrying the KSHV genome. The viral interferon-regulatory factor-3 (vIRF-3) was found to be required for proliferation and survival of cultured PEL cells. Knock-down of vIRF-3 expression by various RNAi approaches unequivocally resulted in reduced proliferation and increased activity of caspase-3 and/or caspase-7. Thus, vIRF-3 can be seen as a bona fide oncogene of KSHV-associated lymphoma. Surprisingly, although the related Epstein-Barr virus (EBV) is usually sufficient to immortalize human B lymphocytes, silencing of vIRF-3 reduced the viability of both EBV− and EBV+ PEL cells. This suggests that KSHV is the driving force in the pathogenesis of PEL.

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Epstein-Barr Virus Immediate-Early Protein BZLF1 Is SUMO-1 Modified and Disrupts Promyelocytic Leukemia Bodies

Journal of Virology ◽

10.1128/jvi.75.5.2388-2399.2001 ◽

2001 ◽

Vol 75 (5) ◽

pp. 2388-2399 ◽

Cited By ~ 171

Author(s):

Amy L. Adamson ◽

Shannon Kenney

Keyword(s):

Cell Lines ◽

Transcriptional Activation ◽

Epstein Barr Virus ◽

Promyelocytic Leukemia ◽

Lytic Replication ◽

Immediate Early ◽

Barr Virus ◽

Early Protein ◽

Pml Bodies ◽

Epstein Barr

ABSTRACT Although the immediate-early proteins of both herpes simplex virus (HSV) and cytomegalovirus (CMV) are known to modify promyelocytic leukemia (PML) (ND10) bodies in the nucleus of the host cell, it has been unclear whether lytic infection with gamma herpesviruses induces a similar effect. The PML protein is induced by interferon, involved in major histocompatibility complex class I presentation, and necessary for certain types of apoptosis. Therefore, it is likely that PML bodies function in an antiviral capacity. SUMO-1 modification of PML is known to be required for the formation of PML bodies. To examine whether Epstein-Barr virus (EBV) lytic replication interferes with PML bodies, we expressed the EBV immediate-early genes BZLF1 (Z) and BRLF1 (R) in EBV-positive cell lines and examined PML localization. Both Z and R expression resulted in PML dispersion in EBV-positive cells. Z but not R expression is sufficient to disrupt PML bodies in EBV-negative cell lines. We show that dispersion of PML bodies by Z requires a portion of the transcriptional activation domain of Z but not the DNA-binding function. As was previously reported for the HSV-1 ICP0 and CMV IE1 proteins, Z reduces the amount of SUMO-1-modified PML. We also found that Z itself is SUMO-1 modified (through amino acid 12) and that Z competes with PML for limiting amounts of SUMO-1. These results suggest that disruption of PML bodies is important for efficient lytic replication of EBV. Furthermore, Z may potentially alter the function of a variety of cellular proteins by inhibiting SUMO-1 modification.

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