Anitbody affinity birth through somatic hypermutation
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1191854 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR31543360.fastq.gz | Fastqsanger.gz | |||
| SRR31543361.fastq.gz | Fastqsanger.gz | |||
| SRR31543362.fastq.gz | Fastqsanger.gz | |||
| SRR31543363.fastq.gz | Fastqsanger.gz | |||
| SRR31543364.fastq.gz | Fastqsanger.gz |
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Project description:B cell somatic hypermutation (SHM) and selection in germinal center (GC)s enhance antibody affinity to antigen. Conventional understanding holds that SHM enhances pre-existing antibody specificities, limiting the scope of SHM-based antibody evolution to those established in the primary repertoire through V(D)J recombination. By tracking pre-defined non-specific B cells, we observed consistent SHM in non-cognate antibody genes after immunization in settings of diverse, polyclonal B and T cells. Removing B cell competition enabled these non-specific yet somatically mutating antibodies to develop entirely new specificities to diverse antigens. Our findings introduce an updated model, where SHM drives antibody diversification without requiring initial antigen specificity. This reveals that B cell competition, rather than a necessity for specific affinity, limits the emergence of new affinities (termed here as affinity birth) by SHM and highlights the mammalian adaptive immune system’s capacity to explore antibody-antigen interactions beyond the epitopes targeted by the V(D)J-dependent primary antibody repertoire.
2024-12-04 | GSE283094 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE39108: UNG shapes the specifity of AID-induced somatic hypermutation in non B cells GSE39114: UNG shapes the specifity of AID-induced somatic hypermutation in B cells Refer to individual Series
2012-07-04 | E-GEOD-39115 | biostudies-arrayexpress
Project description:Topologically Associated Domains Delineate Susceptibility to Somatic Hypermutation
| PRJNA587064 | ENA
Project description:Somatic hypermutation (SHM) introduces point mutations into immunoglobulin (Ig) genes of activated B cells to support the process of antibody affinity maturation but also causes "off-target" mutations in other parts of the genome. We have used sensitive lentiviral SHM reporter vectors and a mutationally active human B cell line to identify dozens of regions of the genome that are intrinsically susceptible to SHM ("hot" regions) and many hundreds of regions that are resistant to SHM ("cold" regions). Hot and cold regions are frequently contained within topologically associated domains (TADs). Comparison of hot and cold TADs reveals that while overall levels of transcription are equal, hot TADs are enriched for NIPBL (a component of the cohesin loader), super enhancers, markers of paused/stalled RNA polymerase 2, and multiple transcription factors implicated in B cell development and targeting of SHM. We demonstrate that at least some hot TADs contain enhancer elements that possess SHM targeting activity and that insertion of a strong Ig SHM-targeting element into a cold TAD renders it hot. Our findings lead to a model for SHM susceptibility involving the cooperative action of cis-acting SHM targeting elements and the dynamic and architectural properties of TADs.
2019-12-04 | GSE139810 | GEO
Project description:The transcription factor Bach2 is required for germinal center formation and somatic hypermutation (SHM) of immunoglobulins, both central to an efficient antibody-mediated immune response. Activation-induced cytidine deaminase (AID) initiates SHM and CSR in germinal centers and has potential to induce human B cell lymphoma. To understand the role of Bach2 in AID-mediated immunoglobulin gene diversification processes, we established a Bach2-deficient DT40 B cell line. We show that in addition to allowing SHM, Bach2 drives immunoglobulin gene conversion (GCV), an important AID-dependent antibody gene diversification process. We demonstrate that Bach2 promotes GCV by increasing the expression of AID. Importantly, we found that the regulation of AID is independent of Blimp-1 and that Bach2-deficient cells have altered expression of several genes regulating AID expression, stability and function. These results demonstrate that Bach2 has a previously unappreciated role in the production of high-affinity antibodies.
2017-03-27 | GSE92430 | GEO
Project description:In this work we illustrate the power of coupling single cell analysis of transcriptional states with somatic hypermutation of germinal center B cells to reveal unanticipated roles of metabolic programs in the positive selection. We use massively parallel 5'-end scRNA-seq to simultaneously capture transcriptome states and mutation profiles of IgH variable genes in individual cells. Our computational analyses reveal that the OXPHOS module is enhanced in GC B cells undergoing positive selection in response to different antigens. Through deleting the Cox10 gene, which encodes a cytochrome oxidase assembly factor, specifically in GC B cells, we demonstrate that OXPHOS activity is required for cell division and positive selection. Furthermore, we show that chemical augmentation of OXPHOS activity facilitates the positive selection of GC B cells in vivo. Our findings therefore reveal that tuning of OXPHOS activity by increased affinity BCRs is critical for clonal expansion and positive selection.
2021-04-16 | GSE154634 | GEO
Project description:We report a novel approach to identify genome-wide somatic hypermutation hotspots from short Illumina H3K4me3 ChIPseq reads in diffuse large B-cell lymphoma cells (DLBCL). Abberant somatic hypermation are known to occur at the promoters of several proto-oncogenes in DLBCL. To identify such events genome-wide, we performed H3K4me3 ChIPseq experiments (as to enrich promoter sequences of actively transcribed genes) in 2 DLBCL cells lines (OCI-Ly1 and OCI-Ly8) and their normal B-cell counterparts, Naive B cells (NBC) and Germinal Center B cells (GCBs). We discover new genes that harbor mutations in their promoter regions that are potentially introduced by the aberrant activation-induced cytosine deaminase activity in lymphoma cell lines, and many of these genes are important for the B cell biology. Moreover, we show that these mutations can affect the activities of these promoters. Our study provides a feasible approach for the detection of promoter mutations and broadens our knowledge on promoter mutations in lymphomas. Examination of 1 histone mark (H3K4me3) in 4 different cell types.
2012-07-16 | E-GEOD-34316 | biostudies-arrayexpress
Project description:SETD2 is the sole chromatin modifier responsible for H3K36me3, a histone mark linked to splicing, transcription initiation and DNA damage response. Homozygous disruption of SETD2 yields a tumor suppressor effect in various cancers. However, SETD2 mutation is virtually always heterozygous in diffuse large B-cell lymphomas (DLBCL). Here we show that heterozygous SETD2 deficiency results in germinal center (GC) hyperplasia and accelerated lymphomagenesis. SETD2 haploinsufficient GC B-cells exhibit increased competitive fitness and reduced DNA damage checkpoint activity, resulting in decreased apoptosis. SETD2 haploinsufficient GCB and lymphoma cells featured increased off- and on-target AICDA induced somatic hypermutation (SHM), complex structural variants such as rygma, and increased translocations including those activating MYC. DNA damage was selectively increased on the non-template strand and H3K36me3 loss was associated with greater RNA Pol II processivity and mutational burden, suggesting that SETD2-mediated H3K36me3 is required for proper sensing of cytosine deamination during transcription. Hence, SETD2 haploinsufficiency delineates a novel GC B-cell context specific oncogenic pathway involving defective epigenetic surveillance of AICDA mediated somatic hypermutation induced off target effects on transcribed genes.
2022-04-06 | GSE189867 | GEO
Project description:Secondary diversification of antibodies through somatic hypermutation (SHM) and class switch recombination (CSR) is a critical component of the immune response. Activation-induced deaminase (AID) initiates both processes by deaminating cytosine residues in immunoglobulin genes. The resulting U:G mismatch can be processed by alternative pathways to give rise to a mutation (SHM) or a DNA double-strand break (CSR). Central to this processing is the activity of uracil-N-glycosylase (UNG), an enzyme normally involved in error-free base excision repair. We used next generation sequencing to analyze the contribution of UNG to the resolution of AID-induced lesions. Loss- and gain-of-function experiments showed that UNG activity can promote both error-prone and high fidelity repair of U:G lesions. Unexpectedly, the balance between these alternative outcomes was influenced by the sequence context of the deaminated cytosine, with individual hotspots exhibiting higher susceptibility to UNG-triggered error-free or error-prone resolution. These results reveal UNG as a new molecular layer that shapes the specificity of AID-induced mutations and may provide new insights into the role of AID in cancer development. Next Generation Sequencing analysis of mutations introduced by AID in activated B lymphocytes from WT and UNG-/- mice (n=4). Activated B cells from AID-/- mice (n=2) were used as negative controls.
2012-07-04 | E-GEOD-39114 | biostudies-arrayexpress
Project description:Somatic hypermutation (SHM) drives the genetic diversity of immunoglobulin genes in activated B cells and supports the generation of antibodies with increased affinity for antigen. SHM is targeted to Ig genes by their enhancers (DIVACs; diversification activators) but how the enhancers mediate this activity is unknown. We show that DIVACs that strongly stimulate SHM increase the phosphorylation of RNA polymerase 2 (Pol2) and Pol2 occupancy in the mutating gene with little or no accompanying increase in elongation-competent Pol2 or production of full length transcripts, indicating the accumulation of stalled Pol2. DIVAC-induced stalling is weakly associated with an increase in the detection of single-stranded DNA bubbles in the mutating target gene. We did not find evidence for anti-sense transcription or an association of H3K27ac with DIVAC activity in the mutating gene. These findings argue for a connection between Pol2 stalling and cis-acting targeting elements in the context of SHM and thus define a mechanistic basis for locus-specific targeting of SHM in the genome. Our results suggest that DIVACs make the target gene a suitable platform for AID-mediated mutation without the need for increasing transcriptional output.
2021-10-22 | GSE180177 | GEO