Epstein-Barr virus latent membrane protein 2A enhances MYC-driven cell cycle progression in a mouse model of B lymphoma

Fish, Kamonwan; Chen, Jia; Longnecker, Richard

doi:10.1182/blood-2013-07-517649

Cited by 49 publications

(66 citation statements)

References 63 publications

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“…A number of potential roles for LMP2A in enhancing EBV persistence and/or EBV-associated lymphomas have been proposed, which include regulating the latent-to-lytic switch (45,46), inducing plasma cell differentiation (35), promoting the survival of B cells that have undergone nonproductive BCR rearrangements (21), cooperating with c-Myc overexpression to induce Burkitt-like lymphomas (50,51), and inhibiting the host immune response (52,53). However, many of those previous studies expressed LMP2A at nonphysiological levels and/or were performed outside the context of the intact viral genome.…”

Section: Discussionmentioning

confidence: 99%

Latent Membrane Protein 1 (LMP1) and LMP2A Collaborate To Promote Epstein-Barr Virus-Induced B Cell Lymphomas in a Cord Blood-Humanized Mouse Model but Are Not Essential

Dong

Tsai

Romero-Masters

et al. 2017

J Virol

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Epstein-Barr virus (EBV) infection is associated with B cell lymphomas in humans. The ability of EBV to convert human B cells into long-lived lymphoblastoid cell lines (LCLs) in vitro requires the collaborative effects of EBNA2 (which hijacks Notch signaling), latent membrane protein 1 (LMP1) (which mimics CD40 signaling), and EBV-encoded nuclear antigen 3A (EBNA3A) and EBNA3C (which inhibit oncogene-induced senescence and apoptosis). However, we recently showed that an LMP1-deleted EBV mutant induces B cell lymphomas in a newly developed cord blood-humanized mouse model that allows EBV-infected B cells to interact with CD4 T cells (the major source of CD40 ligand). Here we examined whether the EBV LMP2A protein, which mimics constitutively active B cell receptor signaling, is required for EBV-induced lymphomas in this model. We find that the deletion of LMP2A delays the onset of EBV-induced lymphomas but does not affect the tumor phenotype or the number of tumors. The simultaneous deletion of both LMP1 and LMP2A results in fewer tumors and a further delay in tumor onset. Nevertheless, the LMP1/LMP2A double mutant induces lymphomas in approximately half of the infected animals. These results indicate that neither LMP1 nor LMP2A is absolutely essential for the ability of EBV to induce B cell lymphomas in the cord blood-humanized mouse model, although the simultaneous loss of both LMP1 and LMP2A decreases the proportion of animals developing tumors and increases the time to tumor onset. Thus, the expression of either LMP1 or LMP2A may be sufficient to promote early-onset EBV-induced tumors in this model. IMPORTANCE EBV causes human lymphomas, but few models are available for dissecting how EBV causes lymphomas in vivo in the context of a host immune response. We recently used a newly developed cord blood-humanized mouse model to show that EBV can cooperate with human CD4 T cells to cause B cell lymphomas even when a major viral transforming protein, LMP1, is deleted. Here we examined whether the EBV protein LMP2A, which mimics B cell receptor signaling, is required for EBV-induced lymphomas in this model. We find that the deletion of LMP2A alone has little effect on the ability of EBV to cause lymphomas but delays tumor onset. The deletion of both LMP1 and LMP2A results in a smaller number of lymphomas in infected animals, with an even more delayed time to tumor onset. These results suggest that LMP1 and LMP2A collaborate to promote early-onset lymphomas in this model, but neither protein is absolutely essential.KEYWORDS EBV, Epstein-Barr virus, LMP1, LMP2A, humanized mouse, lymphoma

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Section: Discussionmentioning

confidence: 99%

Latent Membrane Protein 1 (LMP1) and LMP2A Collaborate To Promote Epstein-Barr Virus-Induced B Cell Lymphomas in a Cord Blood-Humanized Mouse Model but Are Not Essential

Dong

Tsai

Romero-Masters

et al. 2017

J Virol

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“…17,18 A series of studies from Longnecker's laboratory revealed that LMP2A may provide survival signaling to B cells in LMP2A-transgenic mice and also facilitate the oncogenicity of c-Myc. 19,20 Of interest, they demonstrated that LMP2A requires Notch1 to alter B-cell gene expression in a very similar manner to the gene expression in Reed-Sternberg cells of EBV-associated Hodgkin disease (HD). 21 In addition, they speculated that these cells can survive with an intact p53 22 because of cell growth being directly promoted through the c-Myc pathway.…”

Section: Introductionmentioning

confidence: 99%

Epstein-Barr virus LMP2A suppresses MHC class II expression by regulating the B-cell transcription factors E47 and PU.1

Lin

Chou

et al. 2015

Blood

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Key Points• EBV LMP2A alters B-cell gene expression; E47 and PU.1 are repressed by LMP2A, resulting in downregulation of MHC class II expression.Oncogenic Epstein-Barr virus (EBV) uses various approaches to escape host immune responses and persist in B cells. Such persistent infections may provide the opportunity for this virus to initiate tumor formation. Using EBV-immortalized lymphoblastoid cell lines (LCLs) as a model, we found that the expression of major histocompatibility complex (MHC) class II and CD74 in B cells is repressed after EBV infection. Class II transactivator (CIITA) is the master regulator of MHC class II-related genes. As expected, CIITA was downregulated in LCLs. We showed that downregulation of CIITA is caused by EBV latent membrane protein 2A (LMP2A) and driven by the CIITA-PIII promoter. Furthermore, we demonstrated that LMP2A-mediated E47 and PU.1 reduction resulted in CIITA suppression. Mechanistically, the LMP2A immunoreceptor tyrosine-based activation motif was critical for the repression of E47 and PU.1 promoter activity via Syk, Src, and the phosphatidylinositol 3-kinase/Akt pathway. Elimination of LMP2A in LCLs using a shLMP2A approach showed that the expression levels of E47, PU.1, CIITA, MHC class II, and CD74 are reversed. These data indicated that the LMP2A may reduce MHC class II expression through interference with the E47/PU.1-CIITA pathway. Finally, we demonstrated that MHC class II may be detected in tonsils and EBV-negative Hodgkin disease but not in EBV-associated posttransplant lymphoproliferative disease and Hodgkin disease. (Blood. 2015;125(14):2228-2238) IntroductionDuring infection, viruses face the various challenges of the host immune response and have evolved a number of immune evasion strategies to enable successful infection of the host cells. Epstein-Barr virus (EBV) is a ubiquitous, human g-herpesvirus that persistently infects more than 90% of the human population.1 EBV has evolved several mechanisms to escape immune surveillance: EBV limits the expression of its proteins and persists in immune B cells. EBV uses various strategies to attenuate the first line of innate immunity; for example, latent membrane protein 1 (LMP1) negatively regulates the expression of the important sensor Toll-like receptor 9, 2 B-cell receptor F1 (BCRF1)-encoded viral interleukin-10 inhibits interferon production, 3 and the tegument protein BPLF1 blocks Toll-like receptor signaling. 4 In counteracting the adaptive immune response, EBV interferes with the major histocompatibility complex (MHC) class I and II antigen presentations, which are the key factors for adaptive immunity. MHC antigens are critical in the cellular immune response, which is important for viral clearance. Several studies have addressed the question how EBV downregulates MHC class I antigen expression. EBNA1 has a glycinealanine repeat motif that protects it from degradation and also inhibits its own synthesis. 5,6 The EBV lytic protein BNLF2a interferes with both the peptide and adenosine triphosphate binding ...

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“…A future study will investigate whether E4-ORF1 represents the undetermined viral protein responsible for the second phase of Ras/Mek/Erk signaling required for optimal Ad protein expression and virion production in Ad-infected cells (32). Multiple DNA virus proteins, including Ad E1A and E4-ORF1, are reported to increase Myc expression (6,(54)(55)(56)(57). Here we showed that E4-ORF1 sustains Myc protein expression in human epithelial cells cultured in serum and growth factor-depleted medium and that this novel E4-ORF1 function is mediated by the combined activities of EGFR, InsR/IGF1R, and PI3K (Fig.…”

Section: Discussionmentioning

confidence: 99%

Adenovirus E4-ORF1 Dysregulates Epidermal Growth Factor and Insulin/Insulin-Like Growth Factor Receptors To Mediate Constitutive Myc Expression

Kong

Kumar

Taruishi

et al. 2015

J Virol

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The E4-ORF1 protein encoded by human adenovirus stimulates viral replication in human epithelial cells by binding and activating cellular phosphatidylinositol 3-kinase (PI3K) at the plasma membrane and cellular Myc in the nucleus. In this study, we showed that E4-ORF1 hijacks the tyrosine kinase activities of cellular epidermal growth factor receptor (EGFR) and insulin receptor (InsR)/insulin-like growth factor receptor 1 (IGF1R), as well as the lipid kinase activity of PI3K, to mediate constitutive Myc protein expression. We additionally demonstrated that EGFR contributes to constitutive Myc expression through the capacity of E4-ORF1 to induce ligand-independent EGFR activation and stimulation of the Ras/Mek/Erk pathway, the latter activity of which was conserved by human adenoviruses. Results further suggested that EGFR normally forms a complex with the cellular PDZ protein Discs Large 1 (Dlg1), a component of the Dlg1:E4-ORF1:PI3K ternary complex that mediates E4-ORF1-induced PI3K activation, and that E4-ORF1 binds the Dlg1:EGFR complex and promotes the association of EGFR with InsR and IGF1R. In addition to its role in constitutive Myc expression, InsR/IGF1R also negatively regulates EGFR autophosphorylation and EGFR-mediated Ras/Mek/Erk signaling, and data suggested that E4-ORF1 binding to Dlg1 antagonizes these activities. Collectively, our findings suggest that in human epithelial cells, E4-ORF1 targets EGFR, InsR/IGF1R, and PI3K at the plasma membrane to activate cytosolic signaling pathways that sustain Myc protein levels in the nucleus. We postulate that E4-ORF1-induced constitutive Myc expression functions to ensure the formation of nuclear E4-ORF1:Myc complexes, which have been shown to activate Myc and to enhance adenovirus replication. O ver 60 human adenovirus (Ad) serotypes are classified into seven subgroups (subgroups A through G) based on oncogenic, hemagglutination, and virion structural protein properties as well as genome sequence similarity (1). Ad is a human pathogen primarily associated with mild, self-limited respiratory diseases but additionally causes gastroenteritis, conjunctivitis, cystitis, and skin rashes (1). Certain viral serotypes, such as Ad type 14 (Ad14), can cause life-threatening symptoms that require hospitalization for up to 40% of otherwise healthy individuals (2), and Ad infections of neonates and immunosuppressed patients are associated with high morbidity and mortality rates (3). However, current treatments for severe Ad infections are controversial and carry significant risks for adverse events (1). Ad is also exploited as a vector for vaccination and gene and cancer therapy as well as a tool of discovery to reveal fundamental mechanisms of the cell and mechanisms for cancer development (1).The Ad early region 4 open reading frame 1 gene (E4-ORF1) encodes a 14-kDa protein required for optimal viral replication (4-6). In humans, subgroup D Ad9 is associated with eye infections (1), whereas Ad9 inoculation into experimental animals elicits estrogen-dependent m...

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Epstein-Barr virus latent membrane protein 2A enhances MYC-driven cell cycle progression in a mouse model of B lymphoma

Cited by 49 publications

References 63 publications

Latent Membrane Protein 1 (LMP1) and LMP2A Collaborate To Promote Epstein-Barr Virus-Induced B Cell Lymphomas in a Cord Blood-Humanized Mouse Model but Are Not Essential

Latent Membrane Protein 1 (LMP1) and LMP2A Collaborate To Promote Epstein-Barr Virus-Induced B Cell Lymphomas in a Cord Blood-Humanized Mouse Model but Are Not Essential

Epstein-Barr virus LMP2A suppresses MHC class II expression by regulating the B-cell transcription factors E47 and PU.1

Adenovirus E4-ORF1 Dysregulates Epidermal Growth Factor and Insulin/Insulin-Like Growth Factor Receptors To Mediate Constitutive Myc Expression

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