Faculty Opinions recommendation of Epstein-Barr virus microRNAs regulate B cell receptor signal transduction and lytic reactivation.

AbstractAntigen recognition by the B cell receptor (BCR) is a physiological trigger for reactivation of Epstein-Barr virus (EBV) and can be recapitulated in vitro by cross-linking of surface immunoglobulins. Previously, we identified a subset of EBV microRNAs (miRNAs) that attenuate BCR signal transduction and subsequently, dampen lytic replication in B cells. The roles of host miRNAs in virus reactivation are not completely understood. To investigate this process, we profiled the small RNAs in latently infected and reactivated Burkitt’s lymphoma cells, and identified several miRNAs, such as miR-141, that are induced upon BCR cross-linking. Notably, EBV encodes a viral miRNA, miR-BART9, with sequence homology to miR-141. To better understand the functions of these two miRNAs, we examined their molecular targets and experimentally validated multiple candidates commonly regulated by both miRNAs. Targets included transcriptional regulators of the EBV immediate early promoters and B cell transcription factors, leading us to hypothesize that these miRNAs modulate kinetics of the latent to lytic switch in B cells. Through functional assays, we identified roles for miR-141 and EBV miR-BART9 and one specific target, FOXO3, in lytic reactivation. Our data support a model whereby EBV exploits BCR-responsive miR-141 and further mimics activity of this miRNA family via a viral miRNA to promote productive virus replication.ImportanceEBV is a human pathogen associated with several malignancies. A key aspect of lifelong virus persistence is the ability to switch between latent and lytic replication modes. Mechanisms governing latency and lytic reactivation are only partly understood, and how the EBV latent to lytic switch is post-transcriptionally regulated remains an outstanding question. This study sheds light on how miR-141 expression is regulated in Burkitt’s lymphoma cells, and identifies a role for FOXO3, a common target of both miR-141 and viral miR-BART9, in modulating EBV reactivation.

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Signal Transduction and Transcription Factor Modification during Reactivation of Epstein-Barr Virus from Latency

Journal of Virology ◽

10.1128/jvi.76.20.10290-10298.2002 ◽

2002 ◽

Vol 76 (20) ◽

pp. 10290-10298 ◽

Cited By ~ 52

Author(s):

Helen Bryant ◽

Paul J. Farrell

Keyword(s):

Signal Transduction ◽

Transcription Factor ◽

B Cell ◽

Epstein Barr Virus ◽

Cell Receptor ◽

Class Ii ◽

B Cell Receptor ◽

Cross Linking ◽

Barr Virus ◽

Epstein Barr

ABSTRACT Reactivation of Epstein-Barr virus (EBV) from latency involves activation of the Zp promoter of the EBV BZLF1 gene. This occurs rapidly and efficiently in response to cross-linking the B-cell receptor on Akata Burkitt's lymphoma cells. After optimizing conditions for induction, signal transduction responses to B-cell receptor cross-linking were observed within 10 min, well before any autoactivation effects of BZLF1 protein. The primary events in reactivation were shown to involve dephosphorylation of the myocyte enhancer factor 2D (MEF-2D) transcription factor via the cyclosporin A-sensitive, calcium-mediated signaling pathway. This and other signal transduction events were correlated with the quantitative promoter analysis reported in the accompanying paper (U. K. Binné, W. Amon, and P. J. Farrell, this issue). Dephosphorylation of MEF-2D is known to be associated with histone acetylase recruitment, correlating with the histone acetylation at Zp during reactivation that we reported previously (Jenkins et al., J. Virol. 74:710-720, 2000). Histone deacetylation in response to phosphorylated MEF-2D can be mediated by class I or class II histone deacetylases (HDACs); HDAC 7 was the most readily detected class II HDAC in Akata and Raji cells, suggesting that it may be involved in Zp repression during latency.

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Rewiring of B cell receptor signaling by Epstein–Barr virus LMP2A

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2007946117 ◽

2020 ◽

Vol 117 (42) ◽

pp. 26318-26327

Author(s):

Kamonwan Fish ◽

Federico Comoglio ◽

Arthur L. Shaffer ◽

Yanlong Ji ◽

Kuan-Ting Pan ◽

...

Keyword(s):

Cell Cycle ◽

B Cells ◽

B Cell ◽

Epstein Barr Virus ◽

Cell Receptor ◽

B Cell Receptor ◽

Barr Virus ◽

Human B Cells ◽

Bcr Signaling ◽

Epstein Barr

Epstein–Barr virus (EBV) infects human B cells and reprograms them to allow virus replication and persistence. One key viral factor in this process is latent membrane protein 2A (LMP2A), which has been described as a B cell receptor (BCR) mimic promoting malignant transformation. However, how LMP2A signaling contributes to tumorigenesis remains elusive. By comparing LMP2A and BCR signaling in primary human B cells using phosphoproteomics and transcriptome profiling, we identified molecular mechanisms through which LMP2A affects B cell biology. Consistent with the literature, we found that LMP2A mimics a subset of BCR signaling events, including tyrosine phosphorylation of the kinase SYK, the calcium initiation complex consisting of BLNK, BTK, and PLCγ2, and its downstream transcription factor NFAT. However, the majority of LMP2A-induced signaling events markedly differed from those induced by BCR stimulation. These included differential phosphorylation of kinases, phosphatases, adaptor proteins, transcription factors such as nuclear factor κB (NF-κB) and TCF3, as well as widespread changes in the transcriptional output of LMP2A-expressing B cells. LMP2A affected apoptosis and cell-cycle checkpoints by dysregulating the expression of apoptosis regulators such as BCl-xL and the tumor suppressor retinoblastoma-associated protein 1 (RB1). LMP2A cooperated with MYC and mutant cyclin D3, two oncogenic drivers of Burkitt lymphoma, to promote proliferation and survival of primary human B cells by counteracting MYC-induced apoptosis and by inhibiting RB1 function, thereby promoting cell-cycle progression. Our results indicate that LMP2A is not a pure BCR mimic but rather rewires intracellular signaling in EBV-infected B cells that optimizes cell survival and proliferation, setting the stage for oncogenic transformation.

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Signatures of B-cell receptor diversity in B lymphocytes following Epstein-Barr virus transformation

Physiological Genomics ◽

10.1152/physiolgenomics.00124.2018 ◽

2019 ◽

Vol 51 (6) ◽

pp. 197-207

Author(s):

Meimei Lai ◽

Qiongdan Wang ◽

Yutian Lu ◽

Xi Xu ◽

Ying Xia ◽

...

Keyword(s):

B Cell ◽

Cell Line ◽

Epstein Barr Virus ◽

High Throughput Sequencing ◽

Cell Receptor ◽

B Cell Receptor ◽

Human Virus ◽

Barr Virus ◽

Ebv Infection ◽

Epstein Barr

Epstein-Barr virus (EBV) is a widespread human virus that establishes latent infection, potentially leading to tumors, hematological disorders, and other severe diseases. EBV infections are associated with diverse symptoms and affect various organs; therefore, early diagnosis and treatment are crucial. B cell receptor (BCR) repertoires of B cell surface immunoglobulins have been widely studied for their association with various infectious diseases. However, the specific genetic changes that modulate the BCR repertoires after an EBV infection are still poorly understood. In this study, we employed high-throughput sequencing (HTS) to investigate the diversity of BCR repertoires in an EBV-transformed lymphoblastic cell line (LCL). Compared with the noninfected control B cell line, the LCL exhibited a decrease in overall BCR diversity but displayed an increase in the expansion of some dominant rearrangements such as IGHV4-31/IGHJ4, IGHV4-59/IGHJ4, IGHV5-51/IGHJ3, and IGHV3-74/IGHJ3. A higher frequency of occurrence of these rearrangement types was confirmed in patients with EBV infection. Interestingly, the IGHV3-74 rearrangement was only detected in EBV-infected children, suggesting that our experimental observations were not coincidental. In addition, we identified a highly dominant consensus motif, CAR(xRx)YGSG(xYx)FD, in complementarity-determining region 3 (CDR3) sequences of the heavy chain in the LCL. Our findings demonstrated the utility of HTS technology for studying the variations in signature motifs of the BCR repertoires after EBV infection. We propose that the analysis of BCR repertoire sequences represents a promising method for diagnosing early EBV infections and developing novel antibody- and vaccine-based therapies against such infections.

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Identification of Protein Tyrosine Kinases Required for B-Cell- Receptor-Mediated Activation of an Epstein-Barr Virus Immediate-Early Gene Promoter

Journal of Virology ◽

10.1128/jvi.78.16.8543-8551.2004 ◽

2004 ◽

Vol 78 (16) ◽

pp. 8543-8551 ◽

Cited By ~ 7

Author(s):

Sandra Lavens ◽

Emmanuel A. Faust ◽

Fang Lu ◽

Michele Jacob ◽

Messele Leta ◽

...

Keyword(s):

Signal Transduction ◽

B Cell ◽

Tyrosine Kinases ◽

Epstein Barr Virus ◽

Cell Receptor ◽

Lytic Cycle ◽

Protein Tyrosine Kinases ◽

Early Gene ◽

Barr Virus ◽

Epstein Barr

ABSTRACT Epstein-Barr Virus (EBV) is a potentially oncogenic herpesvirus that infects >90% of the world's population. EBV exists predominantly as a latent infection in B lymphocytes, with periodic lytic-cycle reactivation essential for cellular and host transmission. Viral reactivation can be stimulated by ligand-induced activation of B-cell-receptor (BCR)-coupled signaling pathways. The critical first step in the transition from latency to the lytic cycle is the expression of the viral immediate-early gene BZLF1 through the transcription activation of its promoter, Zp. However, the BCR-coupled signal transduction cascade(s) leading to the induction of Zp and the expression of the BZLF1 gene product, Zta, is currently unclear. A major obstacle to delineating the relevant signal transduction events has been the lack of a model of EBV infection that is amenable to genetic manipulation. The use of the avian B-cell line DT40 has proven to be a powerful tool for delineating BCR-mediated signal transduction pathways that appear to be highly conserved between avian and mammalian systems. We demonstrate that the DT40 cell line is a robust and genetically tractable system for the study of BCR-mediated signaling pathways leading to transcriptional activation of BZLF1. Using this system, we demonstrate that activation of Zp requires the BCR-coupled protein tyrosine kinases Syk and Btk and that it is positively regulated by Lyn. Thus, the use of DT40 cells has allowed us to delineate the early signaling components required for BCR-dependent reactivation of latent EBV, and this system is likely to prove useful for further dissection of the downstream signaling cascades involved.

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Epstein-Barr Virus LMP2A Drives B Cell Development and Survival in the Absence of Normal B Cell Receptor Signals

Immunity ◽

10.1016/s1074-7613(00)80623-8 ◽

1998 ◽

Vol 9 (3) ◽

pp. 405-411 ◽

Cited By ~ 396

Author(s):

Robert G Caldwell ◽

Joanna B Wilson ◽

Steven J Anderson ◽

Richard Longnecker

Keyword(s):

B Cell ◽

Epstein Barr Virus ◽

Cell Receptor ◽

Cell Development ◽

B Cell Development ◽

B Cell Receptor ◽

Barr Virus ◽

Epstein Barr

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B Cell Receptor-Responsive miR-141 Enhances Epstein-Barr Virus Lytic Cycle via FOXO3 Inhibition

mSphere ◽

10.1128/msphere.00093-21 ◽

2021 ◽

Vol 6 (2) ◽

Author(s):

Yan Chen ◽

Devin N. Fachko ◽

Nikita S. Ivanov ◽

Rebecca L. Skalsky

Keyword(s):

B Cells ◽

B Cell ◽

Epstein Barr Virus ◽

Cell Receptor ◽

Lytic Replication ◽

B Cell Receptor ◽

Lytic Cycle ◽

Cross Linking ◽

Barr Virus ◽

Epstein Barr

ABSTRACT Antigen recognition by the B cell receptor (BCR) is a physiological trigger for reactivation of Epstein-Barr virus (EBV) and can be recapitulated in vitro by cross-linking of surface immunoglobulins. Previously, we identified a subset of EBV microRNAs (miRNAs) that attenuate BCR signal transduction and subsequently dampen lytic reactivation in B cells. The roles of host miRNAs in the EBV lytic cycle are not completely understood. Here, we profiled the small RNAs in reactivated Burkitt lymphoma cells and identified several miRNAs, such as miR-141, that are induced upon BCR cross-linking. Notably, EBV encodes a viral miRNA, miR-BART9, with sequence homology to miR-141. To better understand the functions of these two miRNAs, we examined their molecular targets and experimentally validated multiple candidates commonly regulated by both miRNAs. Targets included B cell transcription factors and known regulators of EBV immediate-early genes, leading us to hypothesize that these miRNAs modulate kinetics of the lytic cascade in B cells. Through functional assays, we identified roles for miR-141 and EBV miR-BART9 and one specific target, FOXO3, in progression of the lytic cycle. Our data support a model whereby EBV exploits BCR-responsive miR-141 and further mimics activity of this miRNA family via a viral miRNA to promote productive lytic replication. IMPORTANCE EBV is a human pathogen associated with several malignancies. A key aspect of lifelong virus persistence is the ability to switch between latent and lytic replication modes. The mechanisms governing latency, reactivation, and progression of the lytic cycle are only partly understood. This study reveals that specific miRNAs can act to support the EBV lytic phase following BCR-mediated reactivation triggers. Furthermore, this study identifies a role for FOXO3, commonly suppressed by both host and viral miRNAs, in modulating progression of the EBV lytic cycle.

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