Parp1 facilitates alternative NHEJ, whereas Parp2 suppresses IgH/c-myc translocations during immunoglobulin class switch recombination

Immunoglobulin class switch recombination (CSR) is initiated by DNA breaks triggered by activation-induced cytidine deaminase (AID). These breaks activate DNA damage response proteins to promote appropriate repair and long-range recombination. Aberrant processing of these breaks, however, results in decreased CSR and/or increased frequency of illegitimate recombination between the immunoglobulin heavy chain locus and oncogenes like c-myc. Here, we have examined the contribution of the DNA damage sensors Parp1 and Parp2 in the resolution of AID-induced DNA breaks during CSR. We find that although Parp enzymatic activity is induced in an AID-dependent manner during CSR, neither Parp1 nor Parp2 are required for CSR. We find however, that Parp1 favors repair of switch regions through a microhomology-mediated pathway and that Parp2 actively suppresses IgH/c-myc translocations. Thus, we define Parp1 as facilitating alternative end-joining and Parp2 as a novel translocation suppressor during CSR.

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The cohesin complex regulates immunoglobulin class switch recombination

Journal of Experimental Medicine ◽

10.1084/jem.20130166 ◽

2013 ◽

Vol 210 (12) ◽

pp. 2495-2502 ◽

Cited By ~ 34

Author(s):

Anne-Sophie Thomas-Claudepierre ◽

Ebe Schiavo ◽

Vincent Heyer ◽

Marjorie Fournier ◽

Adeline Page ◽

...

Keyword(s):

Cytidine Deaminase ◽

Class Switch Recombination ◽

Nonhomologous End Joining ◽

Cohesin Complex ◽

Dna Breaks ◽

End Joining ◽

Regulatory Subunits ◽

Class Switch ◽

Chromatid Cohesion ◽

Switch Regions

Immunoglobulin (Ig) class switch recombination (CSR) is initiated by the transcription-coupled recruitment of activation-induced cytidine deaminase (AID) to switch regions and by the subsequent generation of double-stranded DNA breaks (DSBs). These DNA breaks are ultimately resolved through the nonhomologous end joining (NHEJ) pathway. We show that during CSR, AID associates with subunits of cohesin, a complex previously implicated in sister chromatid cohesion, DNA repair, and the formation of DNA loops between enhancers and promoters. Furthermore, we implicate the cohesin complex in the mechanism of CSR by showing that cohesin is dynamically recruited to the Sμ-Cμ region of the IgH locus during CSR and that knockdown of cohesin or its regulatory subunits results in impaired CSR and increased usage of microhomology-based end joining.

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53BP1 regulates DNA resection and the choice between classical and alternative end joining during class switch recombination

Journal of Experimental Medicine ◽

10.1084/jem.20100244 ◽

2010 ◽

Vol 207 (4) ◽

pp. 855-865 ◽

Cited By ~ 190

Author(s):

Anne Bothmer ◽

Davide F. Robbiani ◽

Niklas Feldhahn ◽

Anna Gazumyan ◽

Andre Nussenzweig ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Dna Double Strand Breaks ◽

End Joining ◽

Response Factors ◽

Class Switch ◽

Damage Response ◽

Switch Regions

Class switch recombination (CSR) diversifies antibodies by joining highly repetitive DNA elements, which are separated by 60–200 kbp. CSR is initiated by activation-induced cytidine deaminase, an enzyme that produces multiple DNA double-strand breaks (DSBs) in switch regions. Switch regions are joined by a mechanism that requires an intact DNA damage response and classical or alternative nonhomologous end joining (A-NHEJ). Among the DNA damage response factors, 53BP1 has the most profound effect on CSR. We explore the role of 53BP1 in intrachromosomal DNA repair using I-SceI to introduce paired DSBs in the IgH locus. We find that the absence of 53BP1 results in an ataxia telangiectasia mutated–dependent increase in DNA end resection and that resected DNA is preferentially repaired by microhomology-mediated A-NHEJ. We propose that 53BP1 favors long-range CSR in part by protecting DNA ends against resection, which prevents A-NHEJ–dependent short-range rejoining of intra–switch region DSBs.

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Rnf8 deficiency impairs class switch recombination, spermatogenesis, and genomic integrity and predisposes for cancer

Journal of Experimental Medicine ◽

10.1084/jem.20092437 ◽

2010 ◽

Vol 207 (5) ◽

pp. 983-997 ◽

Cited By ~ 73

Author(s):

Li Li ◽

Marie-Jo Halaby ◽

Anne Hakem ◽

Renato Cardoso ◽

Samah El Ghamrasni ◽

...

Keyword(s):

Dna Damage ◽

Class Switch Recombination ◽

Dependent Manner ◽

Dna Double Strand Breaks ◽

Dna Breaks ◽

Class Switch ◽

Physiological Processes ◽

Increased Sensitivity

Signaling and repair of DNA double-strand breaks (DSBs) are critical for preventing immunodeficiency and cancer. These DNA breaks result from exogenous and endogenous DNA insults but are also programmed to occur during physiological processes such as meiosis and immunoglobulin heavy chain (IgH) class switch recombination (CSR). Recent studies reported that the E3 ligase RNF8 plays important roles in propagating DNA DSB signals and thereby facilitating the recruitment of various DNA damage response proteins, such as 53BP1 and BRCA1, to sites of damage. Using mouse models for Rnf8 mutation, we report that Rnf8 deficiency leads to impaired spermatogenesis and increased sensitivity to ionizing radiation both in vitro and in vivo. We also demonstrate the existence of alternative Rnf8-independent mechanisms that respond to irradiation and accounts for the partial recruitment of 53bp1 to sites of DNA damage in activated Rnf8−/− B cells. Remarkably, IgH CSR is impaired in a gene dose-dependent manner in Rnf8 mutant mice, revealing that these mice are immunodeficient. In addition, Rnf8−/− mice exhibit increased genomic instability and elevated risks for tumorigenesis indicating that Rnf8 is a novel tumor suppressor. These data unravel the in vivo pleiotropic effects of Rnf8.

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A primary immunodeficiency characterized by defective immunoglobulin class switch recombination and impaired DNA repair

Journal of Experimental Medicine ◽

10.1084/jem.20070087 ◽

2007 ◽

Vol 204 (5) ◽

pp. 1207-1216 ◽

Cited By ~ 36

Author(s):

Sophie Péron ◽

Qiang Pan-Hammarström ◽

Kohsuke Imai ◽

Likun Du ◽

Nadine Taubenheim ◽

...

Keyword(s):

Dna Repair ◽

Somatic Hypermutation ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Cd40 Ligand ◽

Dna Breaks ◽

Immunoglobulin Class ◽

Class Switch ◽

Double Stranded Dna ◽

Cd40 Activation

Immunoglobulin class switch recombination (CSR) deficiencies are rare primary immunodeficiencies, characterized by a lack of switched isotype (IgG, IgA, or IgE) production, variably associated with abnormal somatic hypermutation (SHM). Deficiencies in CD40 ligand, CD40, activation-induced cytidine deaminase, and uracil-N-glycosylase may account for this syndrome. We previously described another Ig CSR deficiency condition, characterized by a defect in CSR downstream of the generation of double-stranded DNA breaks in switch (S) μ regions. Further analysis performed with the cells of five affected patients showed that the Ig CSR deficiency was associated with an abnormal formation of the S junctions characterized by microhomology and with increased cell radiosensitivity. In addition, SHM was skewed toward transitions at G/C residues. Overall, these findings suggest that a unique Ig CSR deficiency phenotype could be related to an as-yet-uncharacterized defect in a DNA repair pathway involved in both CSR and SHM events.

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Human PMS2 deficiency is associated with impaired immunoglobulin class switch recombination

Journal of Experimental Medicine ◽

10.1084/jem.20080789 ◽

2008 ◽

Vol 205 (11) ◽

pp. 2465-2472 ◽

Cited By ~ 110

Author(s):

Sophie Péron ◽

Ayse Metin ◽

Pauline Gardès ◽

Marie-Alexandra Alyanakian ◽

Eamonn Sheridan ◽

...

Keyword(s):

Somatic Hypermutation ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Dna Breaks ◽

Gene Encoding ◽

Class Switch ◽

Double Strand Dna Breaks ◽

Switch Regions

Immunoglobulin (Ig) class switch recombination (CSR) deficiencies are rare primary immunodeficiencies characterized by the lack of switched isotype (IgG/IgA/IgE) production. In some cases, CSR deficiencies can be associated with abnormal somatic hypermutation. Analysis of CSR deficiencies has helped reveal the key functions of CSR-triggering molecules, i.e., CD40L, CD40, and effector molecules such as activation-induced cytidine deaminase and uracil N-glycosylase. We report a new form of B cell–intrinsic CSR deficiency found in three patients with deleterious, homozygous mutations in the gene encoding the PMS2 component of the mismatch repair machinery. CSR was found partially defective in vivo and markedly impaired in vitro. It is characterized by the defective occurrence of double-strand DNA breaks (DSBs) in switch regions and abnormal formation of switch junctions. This observation strongly suggests a role for PMS2 in CSR-induced DSB generation.

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Epigenetic tethering of AID to the donor switch region during immunoglobulin class switch recombination

Journal of Experimental Medicine ◽

10.1084/jem.20110118 ◽

2011 ◽

Vol 208 (8) ◽

pp. 1649-1660 ◽

Cited By ~ 82

Author(s):

Beena Patricia Jeevan-Raj ◽

Isabelle Robert ◽

Vincent Heyer ◽

Adeline Page ◽

Jing H. Wang ◽

...

Keyword(s):

Somatic Hypermutation ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Epigenetic Modifications ◽

Dna Breaks ◽

Switch Region ◽

Heterochromatin Protein 1 ◽

Immunoglobulin Class ◽

Class Switch

Immunoglobulin class switch recombination (CSR) is initiated by double-stranded DNA breaks (DSBs) in switch regions triggered by activation-induced cytidine deaminase (AID). Although CSR correlates with epigenetic modifications at the IgH locus, the relationship between these modifications and AID remains unknown. In this study, we show that during CSR, AID forms a complex with KAP1 (KRAB domain–associated protein 1) and HP1 (heterochromatin protein 1) that is tethered to the donor switch region (Sμ) bearing H3K9me3 (trimethylated histone H3 at lysine 9) in vivo. Furthermore, in vivo disruption of this complex results in impaired AID recruitment to Sμ, inefficient DSB formation, and a concomitant defect in CSR but not in somatic hypermutation. We propose that KAP1 and HP1 tether AID to H3K9me3 residues at the donor switch region, thus providing a mechanism linking AID to epigenetic modifications during CSR.

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Histone methyltransferase MMSET promotes AID-mediated DNA breaks at the donor switch region during class switch recombination

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1701366114 ◽

2017 ◽

Vol 114 (49) ◽

pp. E10560-E10567 ◽

Cited By ~ 6

Author(s):

Hai Vu Nguyen ◽

Junchao Dong ◽

Rohit A. Panchakshari ◽

Vipul Kumar ◽

Frederick W. Alt ◽

...

Keyword(s):

B Cells ◽

Cytidine Deaminase ◽

Class Switch Recombination ◽

Histone Methyltransferase ◽

Nonhomologous End Joining ◽

Dna Double Strand Breaks ◽

Dna Breaks ◽

Set Domain ◽

End Joining ◽

Class Switch

In B cells, Ig class switch recombination (CSR) is initiated by activation-induced cytidine deaminase (AID), the activity of which leads to DNA double-strand breaks (DSBs) within IgH switch (S) regions. Preferential targeting of AID-mediated DSBs to S sequences is critical for allowing diversification of antibody functions, while minimizing potential off-target oncogenic events. Here, we used gene targeted inactivation of histone methyltransferase (HMT) multiple myeloma SET domain (MMSET) in mouse B cells and the CH12F3 cell line to explore its role in CSR. We find that deletion of MMSET-II, the isoform containing the catalytic SET domain, inhibits CSR without affecting either IgH germline transcription or joining of DSBs within S regions by classical nonhomologous end joining (C-NHEJ). Instead, we find that MMSET-II inactivation leads to decreased AID recruitment and DSBs at the upstream donor Sμ region. Our findings suggest a role for the HMT MMSET in promoting AID-mediated DNA breaks during CSR.

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