Comparison of Bach2-tdRFP high expression and low expression NP-specific IgG1 light zone GC B cells
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE77319 | GEO | 2016/05/09
SECONDARY ACCESSION(S): PRJNA310018
REPOSITORIES: GEO
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Project description:Despite the importance of memory B cells for protection from recurrent infection, how these cells are selected during germinal center (GC) reactions remains unclear. We show here that light zone (LZ) GC B cells with lower affinity BCRs express a less CD40 signature and relatively high levels of Bach2, being prone to enter the memory B cell pool. We also find that Bach2 contributes to memory B cell generation in a Blimp-1 independent manner and that its higher expression confers on LZ GC cells a more advantage for entering the memory B cell compartment. Thus, our data support an instructive model in which weak T cell help keeps Bach2 expression relatively high, thereby being predisposed to enter the memory pool.
2016-05-09 | GSE73729 | GEO
Project description:The mechanisms involved in the maintenance of memory IgE responses are poorly understood, and the role played by germinal center (GC) IgE cells in these memory responses is particularly unclear. IgE B-cell differentiation is characterized by a transient GC phase, a bias towards the plasma cell (PC) fate, and dependence on sequential switching for the production of high-affinity IgE. We show here that IgE GC B cells are unfit to undergo the conventional GC differentiation program due to impaired B-cell receptor function and increased apoptosis. IgE GC cells fail to populate the GC light zone and are unable to contribute to the memory and long-lived PC compartments. Furthermore, we demonstrate that direct and sequential switching are linked to distinct B-cell differentiation fates: direct switching generates IgE GC cells, whereas sequential switching gives rise to IgE plasma cells. We propose a comprehensive model for the generation and memory of IgE responses. The purpose of this analysis was to: 1) identify expression differences between IgE and IgG1 B lymphocytes, 2) identify GC Dark Zone (DZ) and Light Zone (LZ) signatures of IgG1 GC cells. For that purpose, we compared in one experiment the gene expression patterns of IgE germinal center (GC) cells, IgG1 GC cells, IgE plasma cells (PC), IgG1 PC and naïve cells. In a second experiment, we compared the expression of IgG1 DZ GC cells with that of IgG1 LZ GC cells. Triplicates obtained from independent sorting experiments were used for all samples except two (IgG1 PC=2 samples; IgE PC=4 samples). Each sample was obtained from a pool of three individual mice. The mice used in the experiment were CeGFP BALB/c mice infected with the parasite N. brasiliensis. CeGFP mice carry an IRES-GFP KI cassette in the 3'UTR of membrane IgE. In these mice, GFP expression marks IgE cells, and a population of IgG1 cells with a rearrangement to Cepsilon in the non-productive (VDJ negative) IgH chromosome.
2013-10-31 | E-GEOD-49033 | biostudies-arrayexpress
Project description:The transcription factor Bach2 serves as a crucial regulator of the germinal center (GC) reaction, which is required for production of high-affinity antibodies and establishment of long-lived B cell memory. However, the stage at which Bach2 controls the GC programs and the precise mechanism underlying these processes remain poorly understood. In this study, we show that genetic ablation of Bach2 in GC B cells of mice impairs their survival and maintenance, and memory B cell formation. These defects can be rescued by enforced expression of anti-apoptotic gene Bcl2. As expected, Bach2-deficient GC B cells are defective in antibody affinity maturation, but have normal somatic hyper mutation and class switch recombination of immunoglobulin genes. Mechanistically, Bach2 controls the GC programs by directly repressing pro-apoptotic gene Bim and a set of genes involved in cell stress response and metabolic processes. Thus, our work reveals the precise roles of Bach2 in the GC biology, and demonstrates that Bach2 acts as a crucial survival regulator of GC B cells, providing a key mechanism underlying GC B maintenance and B cell memory formation.
2022-06-05 | GSE205400 | GEO
Project description:Food allergy is caused by allergen-specific IgE but little is known about the B cell memory of persistent responses. Here we describe in pediatric peanut allergy a population of CD23+IgG1 memory B cells that contains peanut-specific clones and generates IgE plasma cells on activation. Through single cell transcriptomics and B cell receptor (BCR) sequencing, we characterized FCER2/CD23+ IgG1 memory B cells co-expressing IL4R, IL13RA1, IGHE and carrying highly mutated BCRs. Further we found that peanut allergen (Ara h 2)-specific B cells were mostly IgG1 memory cells, carried highly mutated BCRs compared to diphtheria toxin-specific B cells, and expressed FCER2 and germlin IGHE. Our findings suggest that CD23+IgG1+ memory B cells transcribing IGHE are a unique memory population containing precursors for pathogenic IgE in food allergy.
2023-11-16 | GSE208235 | GEO
Project description:Germinal centers (GC) arise within B cell follicles upon antigenic challenge. In the dark zones (DZ) of GCs, B cells proliferate and hypermutate their immunoglobulin genes, and mutants with increased affinity are positively selected in the light zone (LZ) to either differentiate into plasma and memory cells, or re-enter the DZ for further refinement. However, the molecular circuits governing GC positive selection are not known. Here, we show that the GC reaction requires the biphasic regulation of c-MYC expression, involving its transient induction during early GC commitment, its repression by BCL6 in DZ B cells, and its re-induction in a subpopulation of positively selected LZ B cells destined to DZ re-entry. Accordingly, acute disruption of MYC function in vivo leads to GC collapse, indicating an essential role in GC physiology. These results have implications for our understanding of GC selection and the role of MYC deregulation in B cell lymphomas. We used microarrays to determine the global gene expression programs that distinguish MYC+ GC B cells from their MYC- negative counterparts. GFPMYC+ and GFPMYC- GC B cell subpopulations were collected by Fluorescence Activated Cell Sorting (FACS) from B cell enriched fractions of splenic mononuclear cell pools of GFPMYC knock-in mice (12 days after SRBC immunization). 5-20ng of total RNA (RIN>9) for each sample was used as a template for linear cDNA amplification (Ovation RNA amplification Kit, NuGen). cDNA was labeled using the Encore Biotin Labeling Kit (NuGen) and hybridized to Affymetrix Mouse 430.2 gene expression arrays.
2012-09-24 | E-GEOD-38304 | biostudies-arrayexpress
Project description:Higher- or lower-affinity GC B cells are directed to plasma cell or recycling GC cell fates; however, how commitment to the plasma cell fate takes place is unclear. By using the level of Bcl6 as a marker, we found that a population of light zone (LZ) GC cells, Bcl6loCD69hi with IRF4 and higher-affinity BCRs or Bcl6hiCD69hi with lower- affinity BCRs, favored the plasma cell or recycling GC cell fate, respectively. Mechanistically, CD40 acted as a dose-dependent regulator for Bcl6loCD69hi cell formation. Furthermore, we found that ICAM1 and SLAM levels on Bcl6loCD69hi cells were higher than on Bcl6hiCD69hi cells, thereby affording more stable TFH-GC B cell contacts, while attenuating this contact down-regulated IRF4. These data support the model that commitment to the plasma cell begins in the GC, and suggest that stability and possibly duration of TFH-GC B cell contacts are key for formation of plasma cell-prone precursor GC cells.
2018-03-29 | GSE109732 | GEO
Project description:Germinal centers (GC) arise within B cell follicles upon antigenic challenge. In the dark zones (DZ) of GCs, B cells proliferate and hypermutate their immunoglobulin genes, and mutants with increased affinity are positively selected in the light zone (LZ) to either differentiate into plasma and memory cells, or re-enter the DZ for further refinement. However, the molecular circuits governing GC positive selection are not known. Here, we show that the GC reaction requires the biphasic regulation of c-MYC expression, involving its transient induction during early GC commitment, its repression by BCL6 in DZ B cells, and its re-induction in a subpopulation of positively selected LZ B cells destined to DZ re-entry. Accordingly, acute disruption of MYC function in vivo leads to GC collapse, indicating an essential role in GC physiology. These results have implications for our understanding of GC selection and the role of MYC deregulation in B cell lymphomas. We used microarrays to determine the global gene expression programs that distinguish MYC+ GC B cells from their MYC- negative counterparts.
2012-09-24 | GSE38304 | GEO
Project description:The mechanism through which lymphoma-associated EZH2 gain-of-function mutations disrupt the immune system to initiate malignant transformation is poorly understood. Conditional expression of mutant Ezh2 in germinal center (GC) B-cells provides a competitive advantage to activated B-cells in expanding the GC light zone (LZ) that is not caused by failure to differentiate and exit the GC. Instead, the LZ enlargement is explained by reduced apoptosis of Ezh2 mutant centrocytes, aberrant LZ proliferation, and failure of these centrocytes to re-enter the dark zone (DZ). Ezh2 mutant GCs fail to engage T-cells and to undergo clonal diversification, exhibiting a reduced IgV mutation frequency. Hence the dominant competitive advantage effect of Ezh2 mutation during early stages of transformation is to uncouple GC B-cells from T-cell help checkpoint, which allows GC B-cells entering the LZ to persist and expand regardless of their immunoglobulin status, reflecting the biology of low-grade follicular lymphomas.
2020-05-11 | GSE138036 | GEO
Project description:The mechanism through which lymphoma-associated EZH2 gain-of-function mutations disrupt the immune system to initiate malignant transformation is poorly understood. Conditional expression of mutant Ezh2 in germinal center (GC) B-cells provides a competitive advantage to activated B-cells in expanding the GC light zone (LZ) that is not caused by failure to differentiate and exit the GC. Instead, the LZ enlargement is explained by reduced apoptosis of Ezh2 mutant centrocytes, aberrant LZ proliferation, and failure of these centrocytes to re-enter the dark zone (DZ). Ezh2 mutant GCs fail to engage T-cells and to undergo clonal diversification, exhibiting a reduced IgV mutation frequency. Hence the dominant competitive advantage effect of Ezh2 mutation during early stages of transformation is to uncouple GC B-cells from T-cell help checkpoint, which allows GC B-cells entering the LZ to persist and expand regardless of their immunoglobulin status, reflecting the biology of low-grade follicular lymphomas.
2020-05-11 | GSE138033 | GEO
Project description:The mechanism through which lymphoma-associated EZH2 gain-of-function mutations disrupt the immune system to initiate malignant transformation is poorly understood. Conditional expression of mutant Ezh2 in germinal center (GC) B-cells provides a competitive advantage to activated B-cells in expanding the GC light zone (LZ) that is not caused by failure to differentiate and exit the GC. Instead, the LZ enlargement is explained by reduced apoptosis of Ezh2 mutant centrocytes, aberrant LZ proliferation, and failure of these centrocytes to re-enter the dark zone (DZ). Ezh2 mutant GCs fail to engage T-cells and to undergo clonal diversification, exhibiting a reduced IgV mutation frequency. Hence the dominant competitive advantage effect of Ezh2 mutation during early stages of transformation is to uncouple GC B-cells from T-cell help checkpoint, which allows GC B-cells entering the LZ to persist and expand regardless of their immunoglobulin status, reflecting the biology of low-grade follicular lymphomas.
2020-05-11 | GSE138032 | GEO