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Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis.

ABSTRACT: Epstein-Barr virus (EBV) is a B cell transforming virus that causes B cell malignancies under conditions of immune suppression. EBV orchestrates B cell transformation through its latent membrane proteins (LMPs) and Epstein-Barr nuclear antigens (EBNAs). We here identify secondary mutations in mouse B cell lymphomas induced by LMP1, to predict and identify key functions of other EBV genes during transformation. We find aberrant activation of early B cell factor 1 (EBF1) to promote transformation of LMP1-expressing B cells by inhibiting their differentiation to plasma cells. EBV EBNA3A phenocopies EBF1 activities in LMP1-expressing B cells, promoting transformation while inhibiting differentiation. In cells expressing LMP1 together with LMP2A, EBNA3A only promotes lymphomagenesis when the EBNA2 target Myc is also overexpressed. Collectively, our data support a model where proproliferative activities of LMP1, LMP2A, and EBNA2 in combination with EBNA3A-mediated inhibition of terminal plasma cell differentiation critically control EBV-mediated B cell lymphomagenesis.

SUBMITTER: Sommermann T

PROVIDER: S-EPMC7322082 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis.

Sommermann Thomas T Yasuda Tomoharu T Ronen Jonathan J Wirtz Tristan T Weber Timm T Sack Ulrike U Caeser Rebecca R Zhang Jingwei J Li Xun X Chu Van Trung VT Jauch Anna A Unger Kristian K Hodson Daniel J DJ Akalin Altuna A Rajewsky Klaus K

Proceedings of the National Academy of Sciences of the United States of America 20200610 25

Epstein-Barr virus (EBV) is a B cell transforming virus that causes B cell malignancies under conditions of immune suppression. EBV orchestrates B cell transformation through its latent membrane proteins (LMPs) and Epstein-Barr nuclear antigens (EBNAs). We here identify secondary mutations in mouse B cell lymphomas induced by LMP1, to predict and identify key functions of other EBV genes during transformation. We find aberrant activation of early B cell factor 1 (EBF1) to promote transformation ...[more]

PMID: 32522871

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Project description:This study compares cellular and viral gene expression in a cord blood-humanized (CBH) mouse model infected with wild-type Epstein-Barr virus (WT), versus a mutant EBV deleted in the latent viral EBNA3C gene (∆3C). EBV causes human B-cell lymphomas and transforms B cells in vitro. EBNA3C, an EBV protein expressed in latently infected cells, is required for EBV transformation of B cells in vitro. However, many EBV+ lymphomas in humans do not express this protein, suggesting that it may be less important in vivo or that cellular mutations and/or signaling pathways may obviate the need for EBNA3C. EBNA3C collaborates with EBNA3A to repress expression of the CDKN2A-encoded tumor suppressors, p16 and p14, and EBNA3C-deleted EBV transforms B cells containing a p16 germline mutation in vitro. We found that the ∆3C virus induced fewer lymphomas (occurring with a delayed onset) in comparison to the wild-type (WT) control virus, although a subset (10/26) of Δ3C-infected CBH mice eventually developed invasive diffuse large B cell lymphomas with type III latency. Both WT and ∆3C viruses induced monoclonal B-cell lymphomas (without somatic hyper-mutation) that were infiltrated by polyclonal T cells. In comparison to WT-infected tumors, ∆3C-infected tumors had greatly increased p16 levels, and RNA-seq analysis revealed a decrease in E2F target gene expression. However, we found that ∆3C-infected tumors expressed c-Myc and cyclin E at similar levels compared to WT-infected tumors, allowing cells to at least partially bypass p16-mediated cell cycle inhibition. Unexpectedly, ∆3C-infected tumors had increased T-cell infiltration, increased expression of T-cell chemokines (CCL5, CCL20 and CCL22) and enhanced type I interferon response in comparison to WT tumors. Together, these results reveal that EBNA3C contributes to, but is not essential for, EBV-induced lymphomagenesis in CBH mice, and suggest potentially important immunologic roles of EBNA3C in vivo.

Dataset Information

Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis.

Publications

Functional interplay of Epstein-Barr virus oncoproteins in a mouse model of B cell lymphomagenesis.

Similar Datasets

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