Ontology highlight
ABSTRACT:
PROVIDER: PRJNA789895 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR17264715_1.fastq.gz | Fastqsanger.gz | |||
| SRR17264715_2.fastq.gz | Fastqsanger.gz | |||
| SRR17264716_1.fastq.gz | Fastqsanger.gz | |||
| SRR17264716_2.fastq.gz | Fastqsanger.gz | |||
| SRR17264717_1.fastq.gz | Fastqsanger.gz |
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Project description:During Class Switch Recombination (CSR) B cells replace the Igh Cμ/δ exons with another downstream constant region exon (CH), altering the antibody isotype. CSR occurs through the introduction of AID-mediated double strand break (DSBs) in switch regions and subsequent ligation of broken ends. Here we developed an assay to investigate the dynamics of DSB introduction in individual cells. We demonstrate that the upstream switch region Sμ is always targeted first during recombination and that the mechanism underlying this control relies on 53BP1. Surprisingly, regulation of break order occurs through residual binding of 53BP1 to chromatin before the introduction of damage and independent of its established role in DNA repair. Using chromosome conformation capture we show that 53BP1 mediates changes in chromatin architecture that affect break order. Finally, our results explain how changes in Igh architecture in the absence of 53BP1 could promote inversional rearrangements that compromise CSR. High Resolution 4C was performed in resting and activated B cells using a bait on the Eμ enhancer
2016-06-16 | E-GEOD-81180 | biostudies-arrayexpress
Project description:The autosomal recessive immunodeficiency, centromeric instability and facial anomalies (ICF) syndrome is a genetically heterogeneous disorder. Despite recent successes in the identification of the underlying gene defects, it is currently unclear how mutations in any of the four known ICF genes cause a primary immunodeficiency. Here we demonstrate that loss of ZBTB24 in B cells from ICF2 patients impairs non-homologous end-joining (NHEJ) during immunoglobulin class-switch recombination and consequently impairs immunoglobulin production and subtype balance. Mechanistically, we found that ZBTB24 associates with poly(ADP-ribose) polymerase 1 (PARP1) and stimulates auto-poly(ADP-ribosyl)ation of this enzyme. The zinc finger in ZBTB24 binds PARP1-associated poly(ADP-ribose) chains and mediates the PARP1-dependent recruitment of ZBTB24 to DNA breaks. Moreover, by binding to poly(ADP-ribose) chains ZBTB24 protects these moieties from degradation by poly(ADP-ribose) glycohydrolase (PARG). This enhances the poly(ADP-ribose)-dependent interaction between PARP1 and the LIG4/XRCC4 NHEJ complex and promotes NHEJ by facilitating the assembly of this repair complex at DNA breaks. Thus, we uncover ZBTB24 as a regulator of PARP1-dependent NHEJ and class-switch recombination, providing a molecular basis for the immunodeficiency in ICF syndrome.
2020-08-19 | PXD014741 | Pride
Project description:DNA damage tolerance (DDT) is crucial for genome integrity maintenance. DDT is mainly carried out by template switch recombination, an error-free mode of overcoming DNA lesions, or translesion DNA synthesis, which is error-prone. Here we investigated the role of Mgs1/WRNIP1 in modulating DDT. Using budding yeast, we found that elimination of Mgs1 in cells lacking Rad5, an essential protein for DDT, activates an alternative mode of DNA damage bypass, driven by recombination, that allows chromosome replication and cell viability under stress conditions that block DNA replication forks. This salvage pathway is RAD52- and RAD59-dependent, requires the DNA polymerase and PCNA-modification at K164, and is enabled by Esc2 and the PCNA-unloader Elg1, being inhibited when Mgs1 is present. We propose that Mgs1 is necessary to prevent a potentially toxic recombination salvage pathway at sites of perturbed replication, which in turn favors Rad5-dependent template switching, thus helping to preserve genome stability.
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Project description:53BP1 governs a specialized, context-specific branch of the classical non-homologous end joining DNA double-strand break repair pathway. Mice lacking 53bp1 (also known as Trp53bp1) are immunodeficient owing to a complete loss of immunoglobulin class-switch recombination, and reduced fidelity of long-range V(D)J recombination. The 53BP1-dependent pathway is also responsible for pathological joining events at dysfunctional telomeres, and its unrestricted activity in Brca1-deficient cellular and tumour models causes genomic instability and oncogenesis. Cells that lack core non-homologous end joining proteins are profoundly radiosensitive, unlike 53BP1-deficient cells, which suggests that 53BP1 and its co-factors act on specific DNA substrates. Here we show that 53BP1 cooperates with its downstream effector protein REV7 to promote non-homologous end joining during class-switch recombination, but REV7 is not required for 53BP1-dependent V(D)J recombination. We identify shieldin—a four-subunit putative single-stranded DNA-binding complex comprising REV7, c20orf196 (SHLD1), FAM35A (SHLD2) and FLJ26957 (SHLD3)— as the factor that explains this specificity. Shieldin is essential for REV7-dependent DNA end-protection and non-homologous end joining during class-switch recombination, and supports toxic non-homologous end joining in Brca1-deficient cells, yet is dispensable for REV7-dependent interstrand cross-link repair. The 53BP1 pathway therefore comprises distinct double-strand break repair activities within chromatin and single-stranded DNA compartments, which explains both the immunological differences between 53bp1- and Rev7- deficient mice and the context specificity of the pathway.
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Project description:We report here high-throughput sequencing analyses of class switch recombination junctions in Lsh deficient B cells with reduced capacity of class switch recombination compared to control B cells.
2020-07-30 | GSE150423 | GEO
Project description:Programmed genetic rearrangements in lymphocytes require transcription at antigen receptor genes to promote accessibility for initiating double-strand break (DSB) formation critical for DNA recombination and repair. Here we show that activated B cells deficient in the PTIP component of the MLL3 (mixed-lineage leukemia 3) /MLL4 complex display impaired histone methylation (H3K4me3) and transcription initiation of downstream switch regions at the immunoglobulin heavy-chain (Igh) locus leading to defective immunoglobulin class-switching. We also show that PTIP accumulation at DSBs contributes to class-switch recombination (CSR) and genome stability independently from Igh switch transcription. These results demonstrate that PTIP promotes specific chromatin changes that control the accessibility of the Igh locus to CSR, and suggest a non-redundant role for the MLL3/MLL4 complex in altering antibody effector function. Genome-wide analysis of histone modifications, PTIP, and Pol II in PTIP-WT and PTIP-KO mouse activated B cells.
2010-08-25 | E-GEOD-20852 | biostudies-arrayexpress
Project description:Activation of splenic B cells induces formation of a 220kb DNA loop between Em and 3’RR enhancers in the immunoglobulin heavy chain locus (IgH). This DNA loop has been proposed to be necessary for the crucial immune diversification mechanism of IgH class switch recombination, but the factors that control its formation are unknown. We show that conditional deletion of transcription factor YY1 in primary splenic B cells results in a dramatic drop in formation of this DNA loop, as well as immunoglobulin class switch recombination. Reconstitution of YY1-deleted splenic B cells with various YY1 mutants showed that the C-terminal half of YY1 lacking the transactivation domain restored both Em-3’RR DNA loop formation as well as class switch recombination. RNA transcript analyses of YY1 conditional deleted splenic B cells suggest that YY1 does not regulate genes needed for DNA looping or CSR. Our results argue for a direct physical mechanism of YY1 mediating long-distance DNA loops and provide strong evidence of the importance of this DNA loop for class switching. Our results provide foundational mechanistic insight into a crucial immune function.
2016-08-06 | GSE85259 | GEO
Project description:Kinase-dependent structural role of DNA-PKcs during immunoglobulin class switch recombination
| PRJNA482753 | ENA
Project description:During Class Switch Recombination (CSR) B cells replace the Igh Cμ/δ exons with another downstream constant region exon (CH), altering the antibody isotype. CSR occurs through the introduction of AID-mediated double strand break (DSBs) in switch regions and subsequent ligation of broken ends. Here we developed an assay to investigate the dynamics of DSB introduction in individual cells. We demonstrate that the upstream switch region Sμ is always targeted first during recombination and that the mechanism underlying this control relies on 53BP1. Surprisingly, regulation of break order occurs through residual binding of 53BP1 to chromatin before the introduction of damage and independent of its established role in DNA repair. Using chromosome conformation capture we show that 53BP1 mediates changes in chromatin architecture that affect break order. Finally, our results explain how changes in Igh architecture in the absence of 53BP1 could promote inversional rearrangements that compromise CSR.
2016-06-16 | GSE81180 | GEO