Project description:Bach2 has been reported to regulate multiple immune cell development and function. Here we report that Bach2 is constitutively expressed in relatively immature NK subsets. Bach2 negatively regulates NK cell development and Bach2 deficiency results in NK cell with mature effector phenotype. Thus, Bach2 functions as a negative regulator of NK cell maturation and function.
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:Through their functional diversification, CD4+ T cells play key roles in both driving and constraining immune-mediated pathology. Transcription factors are critical in the generation and maintenance of cellular diversity and negative regulators antagonistic to alternate fates often act in conjunction with positive regulators to stabilize lineage specification1. Polymorphisms within the locus encoding a transcription factor BACH2 are associated with diverse immune-mediated diseases including asthma2, multiple sclerosis3, Crohn¹s disease4-5, coeliac disease6, vitiligo7 and type 1 diabetes8. A role for Bach2 in maintaining immune homeostasis, however, has not been established. Here, we define Bach2 as a broad regulator of immune activation that stabilizes immunoregulatory capacity while repressing the differentiation programmes of multiple effector lineages in CD4+ T cells. Bach2 was required for efficient formation of regulatory (Treg) cells and consequently for suppression of lethal inflammation in a manner that was Treg cell dependent. Assessment of the genome-wide function of Bach2, however, revealed that it represses genes associated with effector cell differentiation. Consequently, its absence during Treg polarization resulted in inappropriate diversion to effector lineages. In addition, Bach2 constrained full effector differentiation within Th1, Th2 and Th17 cell lineages. These findings identify Bach2 as a key regulator of CD4+ T-cell differentiation that prevents inflammatory disease by controlling the balance between tolerance and immunity. The role of Bach2t to regulate immune homeostasis was investigated by mapping DNA binding profiles of Bach2 in iTreg condition. The function of Bach2 was also evaluated by comparing transcriptome in WT and Bach2-deficient iTreg cells and further comparison was done with transcriptome in naive, Th1, Th2, and Th17 conditions.
Project description:Through their functional diversification, CD4+ T cells play key roles in both driving and constraining immune-mediated pathology. Transcription factors are critical in the generation and maintenance of cellular diversity and negative regulators antagonistic to alternate fates often act in conjunction with positive regulators to stabilize lineage specification1. Polymorphisms within the locus encoding a transcription factor BACH2 are associated with diverse immune-mediated diseases including asthma2, multiple sclerosis3, Crohn¹s disease4-5, coeliac disease6, vitiligo7 and type 1 diabetes8. A role for Bach2 in maintaining immune homeostasis, however, has not been established. Here, we define Bach2 as a broad regulator of immune activation that stabilizes immunoregulatory capacity while repressing the differentiation programmes of multiple effector lineages in CD4+ T cells. Bach2 was required for efficient formation of regulatory (Treg) cells and consequently for suppression of lethal inflammation in a manner that was Treg cell dependent. Assessment of the genome-wide function of Bach2, however, revealed that it represses genes associated with effector cell differentiation. Consequently, its absence during Treg polarization resulted in inappropriate diversion to effector lineages. In addition, Bach2 constrained full effector differentiation within Th1, Th2 and Th17 cell lineages. These findings identify Bach2 as a key regulator of CD4+ T-cell differentiation that prevents inflammatory disease by controlling the balance between tolerance and immunity.
Project description:Natural killer (NK) cells are critical to immune surveillance against infections and cancer. Their role in immune surveillance requires that NK cells are present within tissues in a quiescent state. Mechanisms by which NK cells remain quiescent in tissues are incompletely elucidated. The transcriptional repressor BACH2 plays a critical role within the adaptive immune system, but its function within innate lymphocytes has been unclear. Here, we show that BACH2 acts as an intrinsic negative regulator of NK cell maturation and function. BACH2 is expressed within developing and mature NK cells and promotes the maintenance of immature NK cells by restricting their maturation in the presence of weak stimulatory signals. Loss of BACH2 within NK cells results in accumulation of activated NK cells with unrestrained cytotoxic function within tissues, which mediate augmented immune surveillance to pulmonary cancer metastasis. These findings establish a critical function of BACH2 as a global negative regulator of innate cytotoxic function and tumor immune surveillance by NK cells.
Project description:T follicular helper (Tfh) cells are essential for germinal center B cell responses; however, the molecular mechanism underlying Tfh cell programming, in particular, the initial Tfh cell development, remains largely unknown. Here, we show that in vivo, despite enhanced non-Tfh effector functions, the deletion of transcription factor Bach2 still results in preferential Tfh cell differentiation. Mechanistically, the deletion of Bach2 leads to the induction of CXCR5 expression even before the up-regulation of Ascl2. Subsequently we identified a novel regulatory element in the murine CXCR5 locus that negatively regulates CXCR5 promoter activities in a Bach2-dependent manner. Furthermore, we find that Bach2 is also essential for CD4+ T cell memory including Tfh cell memory. These results demonstrate that Bach2 is a novel critical player in controlling Tfh cell responses.
Project description:Through a diversity of functional lineages, cells of the innate and adaptive immune system either drive or constrain immune reactions within tumors. Thus, while the immune system has a powerful ability to recognize and kill cancer cells, this function is often suppressed preventing clearance of disease. The transcription factor (TF) BACH2 controls the differentiation and function of multiple innate and adaptive immune lineages, but its role in regulating tumor immunity is not known. Here, we demonstrate that BACH2 is required to establish immunosuppression within tumors. We found that growth of subcutaneously implanted tumors was markedly impaired in Bach2-deficient mice and coincided with intratumoral activation of both innate and adaptive immunity but was dependent upon adaptive immunity. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression. These findings demonstrate that BACH2 is a key component of the molecular programme of tumor immunosuppression and identify a new target for development of therapies aimed at reversing immunosuppression in cancer. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression.
Project description:The molecular circuits that direct early T-dependent B cell responses and alternative cell-fate decisions remain poorly understood. Here, we show that either B cell receptor (BCR) or CD40 signals promoted mTORC1-dependent translation of the transcription factor Bach2. Transient up-regulation of Bach2 protein restrained activated B cell expansion and differentiation into plasma cell while promoting the germinal center (GC) and memory B cell fates at the pre-GC stage. However, enforced Bach2 expression facilitated memory B cell generation versus other cell fates. Mechanistically, Bach2 limited access of AP-1 factors and formed a reciprocal repression loop with IRF4. BCR and CD40 signals also down-regulated Bach2 transcript in antigen-activated B cells, and diversified its abundance in various effector populations, predisposing Bach2 protein expression and subsequent cell-fate choices during memory recall and GC reaction. Thus signaling-induced differential dynamics of Bach2 protein and mRNA in activated B cell control their cell-fate outcomes and imprint the fate of their descendant effector cells.
Project description:Investigation of global gene expression levels between B cells, Natural killer cells and Natural killer B cells Gene expression profiling using sorted B cells, Natural killer cells and Natural killer B cells from WT mouse spleen. Total RNA extracted from WT cells were quantified by the NanoDrop ND-1000 and RNA integrity was assessed by standard denaturing agarose gel electrophoresis. The sample preparation and microarray hybridization were performed based on the NimbleGenâs standard protocols.