UnAIDed Class-Switching in activated B-cells reveals intrinsic features of a self-cleaving IgH locus
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA758901 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR15668725.fastq.gz | Fastqsanger.gz | |||
| SRR15668726.fastq.gz | Fastqsanger.gz | |||
| SRR15668727.fastq.gz | Fastqsanger.gz | |||
| SRR15668728.fastq.gz | Fastqsanger.gz | |||
| SRR15668729.fastq.gz | Fastqsanger.gz |
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Project description:Activation-induced deaminase (AID) is the major actor of immunoglobulin (Ig) genes diversification in germinal center B cells. From its first description, it was considered as mandatory for class switch recombination (CSR) and this discovery initiated a long quest for all of the AID-interacting factors controlling its activity. The mechanisms focusing AID-mediated DNA lesions to given target sequences remain incompletely understood, with regards to the detailed characterization of optimal substrates in which cytidine deamination will lead to double strand breaks (DSBs) and chromosomal cleavage. In an effort to reconsider whether such CSR breaks absolutely require AID, we herein provide evidence refuting this dogma in both human and mouse B lymphocytes, based on deep-sequencing approaches. In activated B-cells from either AID-deficient mice or human AID-deficient patients, we report an intrinsic ability of the IgH locus to undergo “on-target” cleavage and subsequent synapsis of broken regions in conditions able to yield low-level CSR. DNA breaks occur in such conditions within the same repetitive S regions usually targeted by AID, but their repair follows a specific pathway with increased usage of microhomology-mediated repair. These data further demonstrate the role of AID machinery as not initiating de novo chromosomal cleavage, but rather catalyzing a process which spontaneously initiates at low levels in an appropriately conformed IgH locus.
2021-10-26 | GSE183034 | GEO
Project description:Activation-induced deaminase (AID) is the major actor of immunoglobulin (Ig) gene diversification in germinal center B-cells. From its first description, it was considered as mandatory for class switch recombination (CSR), and this discovery initiated a long quest for all of the AID-interacting factors controlling its activity. The mechanisms focusing AID-mediated DNA lesions to given target sequences remain incompletely understood with regards the detailed characterization of optimal substrates in which cytidine deamination will lead to double strand breaks (DSBs) and chromosomal cleavage. In an effort to reconsider whether such CSR breaks absolutely require AID, we herein provide evidence, based on deep-sequencing approaches, showing that this dogma is not absolute in both human and mouse B lymphocytes. In activated B-cells from either AID-deficient mice or human AID-deficient patients, we report an intrinsic ability of the IgH locus to undergo "on-target" cleavage and subsequent synapsis of broken regions in conditions able to yield low-level CSR. DNA breaks occur in such conditions within the same repetitive S regions usually targeted by AID, but their repair follows a specific pathway with increased usage of microhomology-mediated repair. These data further demonstrate the role of AID machinery as not initiating de novo chromosomal cleavage but rather catalyzing a process which spontaneously initiates at low levels in an appropriately conformed IgH locus.
| S-EPMC8581400 | biostudies-literature
Project description:The interconnection between metabolic programming and chromatin remodeling during IgA class switching suggest that HIF-1a-dependent glycolytic flux may control the epigenetic modification at α class switching region (Sα) in the Igh locus. To test our hypothesis, histone acetylation was analyzed by chromatin immunoprecipitation sequencing (ChIP-seq) (H3K9ac and H3K27ac) in Hif-1a deficient and control B cell during IgA class switching. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for histone modifications H3K27ac and H3K9ac in B cell from WT and HIF-1a deficient mice.
2025-01-08 | GSE228366 | GEO
Project description:Intrinsic transcriptional heterogeneity in B cells controls early class switching to IgE
| PRJEB14546 | ENA
Project description:'Non-coding transcripts originating upstream of the immunoglobulin constant region (I-transcripts) are required to direct activation-induced deaminase to initiate class switching in B cells. Differential regulation of I and I1 transcription in response to interleukin-4 (IL-4), hence class switching to IgE and IgG1, is not fully understood. Here we combine novel mouse reporters and single-cell RNA-seq to reveal the heterogeneity in IL-4 induced I-transcription. Transgenic mice were generated with one allele labelled with an eGFP fluorescent reporter gene in the first exon of the gamma-1 non-coding RNA and one allele with a tdTom fluorescent reporter gene in the first exon of the epsilon non-coding RNA. Ex vivo splenic B cells from these mice were stimulated with IL-4, lipopolysaccharide and B cell activating factor. After 24 hours culture, cell were sorted according to their fluorescence and used for single-cell mRNA-sequencing. Two independent experiments were performed (labelled as ''batch 1'' and ''batch 2'').'
2016-12-08 | E-MTAB-4825 | biostudies-arrayexpress
Project description:Although immunoglobulin class-switching from IgM to IgG enhances B cell receptor (BCR) signalling and antibody responses, certain subsets of B cell lymphomas retain unswitched IgM BCRs despite signs of class-switching in the immunoglobulin heavy chain loci. This suggests that expression of the IgG BCR suppresses progression of specific lymphoma subsets. We found that inducing BCR class switching from IgM to IgG1 or IgG4 inhibits proliferation of B EZB DLBCL lymphoma cell lines. To understand changes associated with class-switching we compared transcritional profiles of isogenic WSU-FSCCL cell lines artificially class-switched to express IgM and IgG BCRs.
2024-05-15 | GSE267440 | 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:Class Switch Recombination (CSR) is a DNA recombination reaction that diversifies the effector component of antibody responses. CSR is initiated by activation-induced cytidine deaminase (AID), which targets transcriptionally active immunoglobulin heavy chain (Igh) switch donor and acceptor DNA. The 3’ Igh super-enhancer, 3’ Regulatory Region (3’RR), is essential for acceptor region transcription, but how this function is regulated is unknown. Here we identify the chromatin reader ZMYND8 as an essential regulator of the 3’RR and CSR. In B cells, ZMYND8 binds promoters and super-enhancers, including the 3’RR, and controls its activity by modulating the enhancer transcriptional status. In its absence, there is increased 3’RR polymerase loading, and decreased acceptor region transcription and CSR. In addition to CSR, ZMYND8 deficiency impairs somatic hypermutation (SHM) of Igh, which is also dependent on the 3’RR. Thus ZMYND8 controls Igh diversification in mature B lymphocytes by regulating the activity of the 3’ Igh super-enhancer.
2018-10-04 | GSE118794 | GEO
Project description:Class-switch recombination (CSR) diversifies antibodies for productive immune responses while maintaining stability of the B cell genome. Transcription at the immunoglobulin heavy-chain (Igh) locus targets CSRassociated DNA damage and is promoted by the BRCT domain-containing PTIP protein. Although PTIP is a unique component of the MLL3/MLL4 chromatin-modifying complex, the mechanisms for how PTIP promotes transcription remain unclear. Here we dissect the minimal structural requirements of PTIP and its different protein complexes using quantitative proteomics in primary lymphocytes. We find that PTIP functions in transcription and CSR separately from its association with the MLL3/MLL4 complex and from its localization to sites of DNA damage. We identify a tandem BRCT domain of PTIP that is sufficient for CSR and identify PA1 as its main functional protein partner. Collectively, we provide genetic and biochemical evidence that a PTIP-PA1 subcomplex functions independently from the MLL3/MLL4 complex to mediate transcription during CSR. These results further our understanding of how multi-functional chromatin-modifying complexes are organized by subcomplexes that harbor unique and distinct activities. Genome-wide analysis of histone modifications in PA1-WT and -KO mouse activated B cells
2015-12-12 | E-GEOD-75930 | biostudies-arrayexpress
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.
2010-08-25 | GSE20852 | GEO