RAG-mediated DNA double-strand breaks activate a cell type–specific checkpoint to inhibit pre–B cell receptor signals

DNA double-strand breaks (DSBs) activate a canonical DNA damage response, including highly conserved cell cycle checkpoint pathways that prevent cells with DSBs from progressing through the cell cycle. In developing B cells, pre–B cell receptor (pre–BCR) signals initiate immunoglobulin light (Igl) chain gene assembly, leading to RAG-mediated DNA DSBs. The pre–BCR also promotes cell cycle entry, which could cause aberrant DSB repair and genome instability in pre–B cells. Here, we show that RAG DSBs inhibit pre–BCR signals through the ATM- and NF-κB2–dependent induction of SPIC, a hematopoietic-specific transcriptional repressor. SPIC inhibits expression of the SYK tyrosine kinase and BLNK adaptor, resulting in suppression of pre–BCR signaling. This regulatory circuit prevents the pre–BCR from inducing additional Igl chain gene rearrangements and driving pre–B cells with RAG DSBs into cycle. We propose that pre–B cells toggle between pre–BCR signals and a RAG DSB-dependent checkpoint to maintain genome stability while iteratively assembling Igl chain genes.

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Faculty Opinions recommendation of RAG-mediated DNA double-strand breaks activate a cell type-specific checkpoint to inhibit pre-B cell receptor signals.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726113433.793524486 ◽

2016 ◽

Author(s):

Lisa Borghesi

Keyword(s):

B Cell ◽

Cell Receptor ◽

B Cell Receptor ◽

Double Strand Breaks ◽

Cell Type ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

A Cell ◽

Cell Type Specific

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RAG-mediated DNA double-strand breaks activate a cell type–specific checkpoint to inhibit pre–B cell receptor signals

The Journal of Cell Biology ◽

10.1083/jcb.2124oia21 ◽

2016 ◽

Vol 212 (4) ◽

pp. 2124OIA21

Author(s):

Jeffrey J. Bednarski ◽

Ruchi Pandey ◽

Emily Schulte ◽

Lynn S. White ◽

Bo-Ruei Chen ◽

...

Keyword(s):

B Cell ◽

Cell Receptor ◽

B Cell Receptor ◽

Double Strand Breaks ◽

Cell Type ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

A Cell ◽

Cell Type Specific

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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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Activation of p38 MAP kinase by DNA double-strand breaks in V(D)J recombination induces a G2/M cell cycle checkpoint

The EMBO Journal ◽

10.1038/sj.emboj.7600972 ◽

2006 ◽

Vol 25 (4) ◽

pp. 763-773 ◽

Cited By ~ 46

Author(s):

Gustavo Pedraza-Alva ◽

Miroslav Koulnis ◽

Colette Charland ◽

Tina Thornton ◽

James L Clements ◽

...

Keyword(s):

Cell Cycle ◽

Map Kinase ◽

P38 Map Kinase ◽

Cell Cycle Checkpoint ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

M Cell ◽

Strand Breaks ◽

Cycle Checkpoint

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Notch1 enhances B-cell receptor-induced apoptosis in mature activated B cells without affecting cell cycle progression and surface IgM expression

Cell Death and Differentiation ◽

10.1038/sj.cdd.4401253 ◽

2003 ◽

Vol 10 (7) ◽

pp. 833-844 ◽

Cited By ~ 20

Author(s):

S Romer ◽

U Saunders ◽

H-M Jäck ◽

B M Jehn

Keyword(s):

Cell Cycle ◽

B Cells ◽

B Cell ◽

Cell Cycle Progression ◽

Cell Receptor ◽

B Cell Receptor ◽

Cycle Progression ◽

Induced Apoptosis ◽

Activated B Cells

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Interferon regulatory factors 4 and 8 induce the expression of Ikaros and Aiolos to down-regulate pre–B-cell receptor and promote cell-cycle withdrawal in pre–B-cell development

Blood ◽

10.1182/blood-2007-08-110106 ◽

2008 ◽

Vol 111 (3) ◽

pp. 1396-1403 ◽

Cited By ~ 77

Author(s):

Shibin Ma ◽

Simanta Pathak ◽

Long Trinh ◽

Runqing Lu

Keyword(s):

Cell Cycle ◽

B Cells ◽

B Cell ◽

Light Chain ◽

Cell Receptor ◽

B Cell Receptor ◽

Regulatory Factors ◽

Surrogate Light Chain ◽

Interferon Regulatory Factors ◽

Molecular Events

Abstract Pre-B lymphocytes consist of 2 distinct cell populations: large pre-B and small pre-B. The large pre-B cells are newly generated pre-B cells that express pre–B-cell receptor (pre-BCR) on the surface and are highly proliferative; small pre-B cells are derived from large pre-B cells that have down-regulated pre-BCR and withdrawn from cell cycle. The molecular events that mediate the transition from cycling pre-B to small, resting pre-B have not been fully elucidated. Here, we show that interferon regulatory factors 4 and 8 (IRF4,8) suppress surrogate light chain expression and down-regulate pre-BCR in pre-B cells. Our studies further reveal that IRF4,8 induce the expression of Ikaros and Aiolos in pre-B cells, and reconstitution of expression of either one is sufficient to suppress surrogate light chain expression and down-regulate pre-BCR in pre-B cells lacking IRF4,8. Interestingly, our results also indicate that pre-B cells undergo growth inhibition and cell-cycle arrest in the presence of IRF4,8. Moreover, we provide evidence that Ikaros and Aiolos are indispensable for the down-regulation of pre-BCR and the cell-cycle withdrawal mediated by IRF4,8. Thus, IRF4,8 orchestrate the transition from large pre-B to small pre-B cells by inducing the expression of Ikaros and Aiolos.

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Pre-B cell receptor–mediated activation of BCL6 induces pre-B cell quiescence through transcriptional repression of MYC

Blood ◽

10.1182/blood-2011-01-331181 ◽

2011 ◽

Vol 118 (15) ◽

pp. 4174-4178 ◽

Cited By ~ 45

Author(s):

Rahul Nahar ◽

Parham Ramezani-Rad ◽

Maximilian Mossner ◽

Cihangir Duy ◽

Leandro Cerchietti ◽

...

Keyword(s):

Cell Cycle ◽

B Cell ◽

Transcriptional Repression ◽

Lymphoblastic Leukemia ◽

Cell Receptor ◽

B Cell Receptor ◽

Cell Surface Expression ◽

Chain Gene ◽

Light Chain Gene ◽

Inducible Activation

Abstract Initial cell surface expression of the pre-B cell receptor induces proliferation. After 2 to 5 divisions, however, large pre-BII (Fraction C') cells exit cell cycle to become resting, small pre-BII cells (Fraction D). The mechanism by which pre-BII cells exit cell cycle, however, is currently unclear. The checkpoint at the Fraction C'-D transition is critical for immunoglobulin light chain gene recombination and to prevent malignant transformation into acute lymphoblastic leukemia. Here we demonstrate that inducible activation of pre-B cell receptor signaling induces cell-cycle exit through up-regulation of the transcriptional repressor BCL6. Inducible activation of BCL6 downstream of the pre-B cell receptor results in transcriptional repression of MYC and CCND2. Hence, pre-B cell receptor-mediated activation of BCL6 limits pre-B cell proliferation and induces cellular quiescence at the small pre-BII (Fraction D) stage.

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