Project description:Analysis of Foxp3 ablated peripheral regulatory T cells. Regulatory T cells require the expression of the transcription factor Foxp3 for thymic development. It is not known whether continuous expression of Foxp3 is required for the maintained function of mature regulatory T cells in the periphery. Results indicate changes to the regulatory T cell developmental program in the absence of Foxp3. Experiment Overall Design: Compare Cre recombinase treated peripheral regulatory T cells possessing a Cre sensitive Foxp3 locus to Cre treated regulatory T cells with a wild type Foxp3 locus. Cre exposure is observed via the Cre sensitive expression of the yellow flourescent protein molecule.
Project description:The Foxp3 transcription factor is a crucial determinant of both regulatory T (TREG) cell development and their functional maintenance. Appropriate modulation of tolerogenic immune responses therefore requires tight regulation of Foxp3 transcriptional output, and this involves both transcriptional and post-translational regulation. Here, we show that during T cell activation, phosphorylation of Foxp3 in TREG cells can be regulated by a TGFβ Activated Kinase 1 (TAK1)-Nemo Like Kinase (NLK) signaling pathway. NLK interacts with Foxp3 in TREG cells and directly phosphorylates Foxp3 on multiple serine residues. This phosphorylation results in stabilization of Foxp3 protein levels by preventing association with the STUB1 E3-ubiquitin protein ligase, resulting in both reduced ubiquitination and proteasome-mediated degradation. Conditional TREG cell NLK-knockout (NLKTREG) results in decreased TREG cell-mediated immunosuppression in vivo and NLK-deficient TREG cell animals develop more severe experimental autoimmune encephalomyelitis. Our data suggest a molecular mechanism, in which stimulation of TCR-mediated signaling can induce a TAK1-NLK pathway to sustain Foxp3 transcriptional activity through stabilization of protein levels, thereby maintaining TREG cell suppressive function. Pharmacological manipulation of this phosphorylation-ubiquitination axis may provide therapeutic opportunities for regulating TREG cell function, for example during cancer immunotherapy.
Project description:The central nervous system (CNS) hypothalamus controls systemic metabolism. Inflammatory CNS processes evolving upon exposure to calorie-rich diet are thought to promote impaired metabolic CNS control, thereby triggering obesity and Type-2 diabetes (T2D). However, immune cells relevant for maintaining hypothalamic integrity remain incompletely understood. Here, we identify hypothalamic CD4+Foxp3+regulatory T(Treg) cells which control local tissue-inflammation. Specifically, upon exposure to a calorie-rich diet, a significant decline in hypothalamus-residing Foxp3+Tregs occurred and was accompanied by increased immune activation of CD4+T cells, infiltrating macrophages and microglia. Microglial proteomes of mice exposed to the hypercaloric challenge confirmed characteristics of immune activation; specifically, mRNA expression profiling of hypothalamic CD4+T cells indicated a Th1-mediated inflammatory state evidenced by high levels of Tbx21, Cxcr3, Cd226 and reduced expression of Ccr7 and S1P1 receptors relevant for recruitment to and retention at inflammatory sites. Using Treg depletion and transfer experiments in vivo, we found that Foxp3+Tregs critically limit hypothalamic immune activation induced by hyper-caloric challenge. Our findings open new avenues in the design of tailored concepts to improve immunometabolic health in obesity and T2D.
Project description:We hypothesize that nuclear factors co-occupying the genetic elements with regulatory T (Treg) cell lineage–specifying factor Foxp3 play critical roles in transcriptional regulation of Treg immune suppression function, thus, offering a unique approach to investigate the factors and their mechanisms controlling Treg-mediated immune tolerance involved in self-tolerance and antitumor immunity. We seek to identify the proteins occupying Foxp3 targets in the resting state or after cells receiving stimulation. To this end, we projected the spatial information (PSI) of Foxp3, Histone H3, or Stat5 onto their adjacent proteins with peroxidase–catalyzed biotin-phenoxyl radicals and identify these biotinylated proteins with tandem mass tag (TMT)–based quantitative mass spectrometry (MS).
Project description:Regulatory T (Treg) cells are involved in self tolerance, immune homeostasis, prevention of autoimmunity, and suppression of immunity to pathogens or tumours. The forkhead transcription factor FOXP3 is essential for Treg cell development and function as mutations in FOXP3 cause severe autoimmunity in mice and humans. However, the FOXP3-dependent molecular mechanisms leading to this severe phenotype are not well understood. Here we introduce the chromatin remodelling enzyme SATB1 (special AT-rich sequence-binding protein-1) as an important target gene of FOXP3. So far, SATB1 has been associated with normal thymic T-cell development, peripheral T-cell homeostasis, TH1/TH2 polarization, and reprogramming of gene expression. In natural and induced murine and human FOXP3+ Treg cells SATB1 expression is significantly reduced. While there is no differential epigenetic regulation of the SATB1 locus between Treg and Teffector cells, FOXP3 reduces SATB1 expression directly as a transcriptional repressor at the SATB1 locus and indirectly via miR-155 induction, which specifically binds to the 3’UTR of the SATB1 mRNA. Reduced SATB1 expression in FOXP3+ cells achieved either by overexpression or induction of FOXP3 is linked to significant reduction in TH1 and TH2 cytokines, while loss of FOXP3 function either by knock down or genetic mutation leads to significant upregulation of SATB1 and subsequent cytokine production. Alltogether, these findings demonstrate that reduced SATB1 expression in Treg cells is necessary for maintenance of a Treg-cell phenotype in vitro and in vivo and places SATB1-mediated T cell-specific modulation of global chromatin remodelling central during the decision process between effector and regulatory T-cell function. Gene expression profiling of freshly isolated CD4+ T cells, separated into CD25 negative and positive subpopulations, from three different donors. FOXP3 is stably and constitutively expressed at a high level in CD4+CD25+ regulatory T cells and at a low level in CD4+CD25- cells.
Project description:Regulatory T (Treg) cells maintain immune tolerance through the action of the master regulator FOXP3, a transcription factor crucial for Treg cells function and homeostasis. We identified an IPEX patient with a FOXP3 mutation in the domain swap interface of the protein (mutant M370I). Recapitulation of this Foxp3 variant in mice led to an autoimmune syndrome similar to the patient and consistent with an unrestrained Th2 immune response. Genomic analysis of Treg cells by RNA-seq, Foxp3 ChIP-seq and H3K27ac-HiChIP revealed a specific de-repression of the T helper type 2 (Th2) transcriptional program leading to the generation of Th2-like Treg cells that are unable to suppress extrinsic Th2 cells. Th2-like Treg cells are characterized by increased intra-chromosomal interactions in the Th2 locus leading to type-2 cytokines production. Our research provides cellular and molecular characterizations of mechanisms used by Foxp3 to restrain Th2 transdifferentiation and promote optimal Treg suppressive function and stability.
Project description:Recent data have shown that Hypermethylated in cancer 1 (HIC1) is an important contributor to iTreg cell development and function. Using affinity-purification and tandem mass spectrometry we systematically characterized the HIC-1 interactome in human iTreg cells. On the basis of these data, we have shown that HIC1 is a part of FOXP3-RUNX1-CBFβ protein complex that regulates Treg signature genes and is indispensable for the suppressive function of FOXP3+ regulatory T cells. SRM was used to validate HIC1 interactors
Project description:FOXP3 is a lineage-defining transcription factor (TF) for immune-suppressive regulatory T cells (Tregs). While mice exclusively express FOXP3 in Tregs, humans also transiently express FOXP3 in stimulated conventional CD4+ T cells (Tconvs). Mechanisms governing these distinct expression patterns remain unknown. Here, we performed CRISPR screens tiling the FOXP3 locus and targeting TFs in human Tregs and Tconvs to discover cis-regulatory elements (CREs) and trans-regulators of FOXP3. Tconv FOXP3 expression depended on a subset of Treg CREs and Tconv-selective positive (TcNS+) and negative (TcNS-) CREs. Combinatorial silencing of Tconv CREs revealed their epistatic logic. The CREs are occupied and regulated by TFs we identified as critical regulators of FOXP3. Finally, mutagenesis of murine TcNS- revealed that it is critical for restriction of FOXP3 expression to Tregs. We discover CRE and TF circuitry controlling FOXP3 expression and reveal evolution of mechanisms regulating a gene indispensable to immune homeostasis.
Project description:FOXP3 is a lineage-defining transcription factor (TF) for immune-suppressive regulatory T cells (Tregs). While mice exclusively express FOXP3 in Tregs, humans also transiently express FOXP3 in stimulated conventional CD4+ T cells (Tconvs). Mechanisms governing these distinct expression patterns remain unknown. Here, we performed CRISPR screens tiling the FOXP3 locus and targeting TFs in human Tregs and Tconvs to discover cis-regulatory elements (CREs) and trans-regulators of FOXP3. Tconv FOXP3 expression depended on a subset of Treg CREs and Tconv-selective positive (TcNS+) and negative (TcNS-) CREs. Combinatorial silencing of Tconv CREs revealed their epistatic logic. The CREs are occupied and regulated by TFs we identified as critical regulators of FOXP3. Finally, mutagenesis of murine TcNS- revealed that it is critical for restriction of FOXP3 expression to Tregs. We discover CRE and TF circuitry controlling FOXP3 expression and reveal evolution of mechanisms regulating a gene indispensable to immune homeostasis.
Project description:Foxp3+Tregcells are essential modulators of immune responses but under specific conditions can acquire inflammatory properties and potentially contribute to disease pathogenesis. Here we show that the transcription factor Blimp1 is a critical regulator of Foxp3+Treg functional plasticity. The intrinsic expression of Blimp1 was required to prevent Treg from producing Th17-associated cytokines and acquiring an inflammatory phenotype while preserving Foxp3 expression. Mechanistically, Blimp1 acts as a direct repressor of the Il17a/Il17f genes in Foxp3+Treg and binding of Blimp1 at this locus is associated with altered chromatin status, reduced binding the co-activator p300, unaltered binding of the Th17-asssociated transcription factor RORt and more abundant binding of IRF4, which was required for the production of IL17A in Blimp1-deficient Foxp3+Tregcells, as shown by IRF4 siRNA-mediated knockdown. Consistent with their capacity to produce inflammatory cytokines, Blimp1-deficient Foxp3+Treg exacerbate Th17-mediated inflammation in vivo indicating that Blimp1 is required to prevent Treg cells from acquiring pathogenic properties