Project description:Bach2 codes for a transcriptional regulator exerting major influences on T cell mediated immune regulation. Effector CTLs derived from in vitro activation of murine CD8+ T cells showed increased proliferative and cytolytic capacity in the absence of BACH2. Before activation, BACH2-deficient CD8+ T cells had a higher abundance of memory and reduced abundance of naïve cells compared to wild-type. CTLs derived from central memory T cells were more potently cytotoxic than those derived from naïve T cells, but even within separated subsets, BACH2-deficiency conferred a cytotoxic advantage. Immunofluorescence and electron microscopy revealed larger granules in BACH2-deficient compared to wild-type CTLs, and proteomic analysis showed an increase in granule content, including perforin and granzymes. Thus, the enhanced cytotoxicity observed in effector CTLs lacking BACH2 arises not only from differences in their initial differentiation state but also inherent production of enlarged cytolytic granules. These results demonstrate how a single gene deletion can produce a CTL super-killer.
Project description:Transcription factor Bach2 has been reported to regulate the development and function of multiple immune cells including T cells and B cells. As a transcription repressor, Bach2 plays its role by repressing the expression of downstream targets. We are interested in whether Bach2 will affect NK cell development and what's the relationship between Bach2 and other transcription factors in regulating NK cell function. Here we try to explore the chromatin accessibility of Bach2 by ATAC-seq. We compared enriched peaks in mouse NK cell from Bach2 conditional knockout mice and control mice.
Project description:We report here the broad transcriptomic program regulated by BACH2 transcription factor. We used a well suited in vitro model of B cell differentiation to evaluate transcriptomic program governed by BACH2 leading to Plasmocyte (PC) differentiation. In this model B cells were cultured with anti-BCR, CpG, CD40L and Interleukin-2 (IL2). This Interleukin triggers PC differentiation by directly repressing BACH2 expression. We artificially inhibit BACH2 expression by siRNA and found that this condition is sufficient to trigger PC differentiation without IL2. To understand global changes induced by enforced BACH2 downregulation we compared Chip-Sequencing data between activated B Cells and BACH2 deficient B cells (siBACH2). We found that BACH2 binds more than 3000 genes across the human genome. RNAsequencing comparing IL2 drivent committed cells and siBACH2 committed cells highlighs a large common trasncriptional program shared by both conditions and involved in B cell destiny. This study provides evidence that BACH2 is a guardian of B cell fate.
Project description:The aim was to investigate how BCL6 genotype affects Bach2 dependent gene expression changes. We compared gene expression profiles of BCL6+/+ and BCL6-/- BCR-ABL1 transformed pre-B cells after inducible overexpression of Bach2.
Project description:Bach2 regulates homeostasis of foxp3+ regulatory T cells and protects against fatal lung disease in mice. Cells from WT and Bach2 KO spleen were isolated. CD4+ CD25+ GITR+ (Treg) cells were sorted by FACS sorting. Total RNAs were extracted from sorted Treg cells using by Rneasy Kit (Qiagen).
Project description:The role of FoxP3+ regulatory T (Treg) cells in the maintenance of immunological tolerance is well established. Recently, genome-wide association studies (GWAS) in humans have associated polymorphisms within the BACH2 locus encoding the transcription factor BTB and CNC homology 1, basic leucine zipper transcription factor 2 (Bach2) with diverse allergic and autoimmune diseases including asthma, multiple sclerosis, Crohn's disease, celiac disease, generalized vitiligo and type 1 diabetes. Common to these diseases is a failure to adequately maintain immunological tolerance. However, a role for Bach2 in this process has not been established. Here, by assessing the phenotype of mice in which the Bach2 gene is disrupted, we demonstrate a non-redundant role for Bach2 in the prevention of a spontaneous lethal inflammatory disorder predominantly affecting the lung and gut with excessive T helper 2 (Th2) responses and formation of circulating autoantibodies. Bach2 was necessary for efficient induction of FoxP3 expression both during thymopoesis and upon stimulation of naïve peripheral CD4+ T cells under Treg polarizing conditions in vitro. Consequently, in bone marrow reconstitution experiments, Bach2 expression within the haematopoetic system was necessary for suppression of lethal autoimmunity in a manner that was FoxP3 dependent. These findings demonstrate a requirement for Bach2 in early lineage commitment of both thymic and induced Treg cells and point to shared mechanisms that underlie diverse allergic and autoimmune disorders that may serve as targets in the development of novel therapeutic strategies. Six samples were collected from separate mice: three Ly5.1+ wildtype thymocyte samples (biological replicates) and three Ly5.1- Bach2 knockout thymocyte samples (biological replicates).
Project description:The transcriptional repressors BCL6 and BACH2 are crucial regulators of germinal center (GC) B-cell fate, and are known to interact and repress transcription of PRDM1, a key driver of plasma cell differentiation. How these factors cooperate is not fully understood. Herein we show that while GC formation is only minimally impaired in Bcl6+/- or Bach2+/- mice, double heterozygous Bcl6+/-Bach2+/- mice exhibit profound reduction in GC formation. Splenic B-cells from Bcl6+/- Bach2+/- mice display accelerated plasmacytic differentiation and high expression of key plasma cell genes such as Prdm1, Xbp1 and CD138. ChIP-seq revealed that in B-cells BACH2 is mostly bound to genes together with its heterodimer partner MAFK. The BACH2-MAFK complex binds to sets of genes known to be involved in the GC response, 60% of which are also targets of BCL6. Approximately 30% of BACH2 peaks overlap with BCL6 including cis-regulatory sequences of the PRDM1 gene. BCL6 also modulates BACH2 protein stability and their protein levels are positively correlated in GC B-cells. Therefore, BCL6 and BACH2 cooperate to orchestrate gene expression patterning in GC B cells through both transcriptional and biochemical mechanisms, which collectively determine the proper initiation and timing of terminal differentiation. ChIP-seq using P18 antibodies in OCI-Ly7 cells
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.
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 keep Bach2 expression relatively high, thereby being predisposed to enter the memory pool.