Project description:The generation of TCRαβ and TCRγδ T cells proceeds through distinct developmental stages in which changing regulatory events control differentiation and lineage outcome. To clarify the underlying mechanisms, we employed RNAseq, ATACseq and ChIPmentation on well-defined thymocyte subsets that represent the continuum of human T cell development. The chromatin accessibility dynamics uncover stage-specific regulatory mechanisms and reveal that human T-lineage commitment is marked by the GATA3- and BCL11B-dependent closing of PU.1 sites. While the ß-selection checkpoint is marked by transcriptional changes and a temporary increase in H3K27me3 without modifications in open chromatin, emerging γδ T cells, that originate from common precursors as ß-selected cells, show dramatic changes in chromatin accessibility which results from strong TCR signaling. Furthermore, we unravel distinct chromatin landscapes between CD4 and CD8 αβ T cells that support their effector functions and reveal gene-specific regulatory mechanism that define mature T cells. This resource provides an important framework for studying gene regulatory mechanisms that drive human normal and malignant T cell development.
Project description:T cell factor 1 (Tcf1) is the first T cell‒specific protein induced in multipotent progenitors following Notch signaling in the thymus, leading to the activation of two major target genes, Gata3 and Bcl11b. Tcf1 deficiency results in partial arrests in T cell development high apoptosis, and increased development of B cells and myeloid cells. Phenotypically, fully T cell‒committed, Tcf1-deficient thymocytes have promiscuous gene expression, an altered epigenetic profile and can de-differentiate into more immature thymocytes and non-T cells. Expressing Bcl11b in Tcf1-deficient cells rescues T cell development, but does not strongly suppress the development of non-T cells; in contrast, expressing Gata3 suppresses the development of non-T cells, but does not rescue T cell development. Thus, T cell development is controlled by a minimal transcription factor network involving Notch signaling, Tcf1, and the subsequent division of labor between Bcl11b and Gata3, thereby ensuring a properly regulated T cell gene expression program
Project description:GATA-binding protein 3 (GATA3) acts as the master transcription factor for type 2 T helper (Th2) cell differentiation and function. However, it is still elusive how GATA3 function is precisely regulated in Th2 cells. Here, we report that the transcription factor B cell lymphoma 11b (Bcl11b), a previously unknown component of GATA3 transcriptional complex, is involved in GATA3-mediated gene regulation. Bcl11b binds to GATA3 through protein-protein interaction, and they co-localize at many important cis-regulatory elements in Th2 cells. The expression of type 2 cytokines, including IL-4, IL-5 and IL-13, is up-regulated in Bcl11b-deficient Th2 cells both in vitro and in vivo; such up-regulation is completely GATA3-dependent. Genome-wide analyses of Bcl11b- and GATA3-regulated gene (from RNA-Seq), co-binding pattern (from ChIP-Seq), and Bcl11b-mediated epigenetic changes (in H3K27ac and DHSs) suggest that GATA3/Bcl11b complex is involved in limiting Th2 gene expression, as well as in inhibiting non-Th2 gene expression. Thus, Bcl11b controls both GATA3-mediated gene activation and repression in Th2 cells.
Project description:GATA-binding protein 3 (GATA3) acts as the master transcription factor for type 2 T helper (Th2) cell differentiation and function. However, it is still elusive how GATA3 function is precisely regulated in Th2 cells. Here, we report that the transcription factor B cell lymphoma 11b (Bcl11b), a previously unknown component of GATA3 transcriptional complex, is involved in GATA3-mediated gene regulation. Bcl11b binds to GATA3 through protein-protein interaction, and they co-localize at many important cis-regulatory elements in Th2 cells. The expression of type 2 cytokines, including IL-4, IL-5 and IL-13, is up-regulated in Bcl11b-deficient Th2 cells both in vitro and in vivo; such up-regulation is completely GATA3-dependent. Genome-wide analyses of Bcl11b- and GATA3-regulated gene (from RNA-Seq), co-binding pattern (from ChIP-Seq), and Bcl11b-mediated epigenetic changes (in H3K27ac and DHSs) suggest that GATA3/Bcl11b complex is involved in limiting Th2 gene expression, as well as in inhibiting non-Th2 gene expression. Thus, Bcl11b controls both GATA3-mediated gene activation and repression in Th2 cells.
Project description:GATA3 plays a crucial role during early T-cell development and also dictates later T-cell differentiation outcomes. However, its role and collaboration with the Notch signaling pathway in the induction of T-lineage specification and commitment have not been fully elucidated. We show that GATA3 deficiency in hematopoietic progenitors results in an early block in T-cell development despite the presence of Notch signals, with a failure to up-regulate Bcl11b expression, leading to a diversion toward myeloid lineage fate. GATA3 deficiency results in dysregulated Cdkn2b expression, leading to apoptosis of early T-lineage cells due to inhibition of CDK4/6 function. We also show that GATA-3 induces Bcl11b, and together with Bcl11b represses Cdkn2b expression. Our findings provide a signaling and transcriptional network by which the T-lineage program in response to Notch signals is realized.
Project description:Naïve CD4+ T-helper cells differentiate into Th2 effector cells during asthma and helminth (worm) infection. Here, we report that mice lacking the transcription factor Bcl11b in mature CD4+ T-cells are incapable of mounting an effective Th2 response in asthma and worm infection, with a major reduction of Th2 cytokine secretion and GATA3 expression. We found that Bcl11b exerts its role in Th2 differentiation through several avenues: (1) association with intronic regions at the Gata3 locus, sustaining GATA3 expression; (2) binding to and restricting chromatin accessibility at the Il4 silencer, located at hypersensitivity site (HS) IV; and (3) restricting Runx3 expression by association with a regulatory region 5’ of Runx3. Thus, in the absence of Bcl11b, the reduction in GATA3 levels combined with increased Runx3 levels and activity at Il4 HS IV silencer and consequently diminished IL-4 expression. This results in reduced chromatin opening at the Th2 locus control region (LCR), Il13 and Il5 promoters, subsequently preventing expression of Th2 cytokine genes and Th2 differentiation. Our results establish a novel role for Bcl11b in the regulatory loop critical for licensing the Th2 program in vivo.
Project description:Naïve CD4+ T-helper cells differentiate into Th2 effector cells during asthma and helminth (worm) infection. Here, we report that mice lacking the transcription factor Bcl11b in mature CD4+ T-cells are incapable of mounting an effective Th2 response in asthma and worm infection, with a major reduction of Th2 cytokine secretion and GATA3 expression. We found that Bcl11b exerts its role in Th2 differentiation through several avenues: (1) association with intronic regions at the Gata3 locus, sustaining GATA3 expression; (2) binding to and restricting chromatin accessibility at the Il4 silencer, located at hypersensitivity site (HS) IV; and (3) restricting Runx3 expression by association with a regulatory region 5’ of Runx3. Thus, in the absence of Bcl11b, the reduction in GATA3 levels combined with increased Runx3 levels and activity at Il4 HS IV silencer and consequently diminished IL-4 expression. This results in reduced chromatin opening at the Th2 locus control region (LCR), Il13 and Il5 promoters, subsequently preventing expression of Th2 cytokine genes and Th2 differentiation. Our results establish a novel role for Bcl11b in the regulatory loop critical for licensing the Th2 program in vivo.
Project description:Notch-dependent BCL11B induction converts thymus seeding precursor cells into committed T cell progenitors that subsequently differentiate into T cells bearing either the γδ or αβ T cell receptor. In human, strong Notch activation favors γδ T cell development at the expense of αβ-lineage differentiation, but the underlying molecular mechanism has remained unclear. Therefore, we performed paired mRNA and miRNA profiling across 11 stages of human T cell development, including developing γδ T cells. We identify the miR-17-92 cluster as a direct Notch target and show that miR-17 promotes human TCRγδ T cell development by targeting BCL11B, a gene required for αβ but not for γδ T cell development. Thus, following its role as a licensing factor to induce BCL11B expression in early T cell precursors, Notch activation limits BCL11B expression through miR-17 until thymocytes have passed the β-selection checkpoint when Notch activation is turned off. Hereby Notch prevents premature BCL11B upregulation that is required for αβ-lineage differentiation and this results in preferential γδ-lineage differentiation. Our work unravels a dual role for Notch in controlling BCL11B expression during intrathymic differentiation and provides a unique resource for understanding the mRNA/miRNA interactions that control human T cell development. We used microarrays in order to profile the gene expression in 11 ex vivo T cell subsets, isolated from human thymus. Cord blood CD34+Lin- HPCs were used as a reference subset for extrathymic HPCs.