Project description:Naïve T cell activation involves at least two signals from an antigen presenting cell (APC), one through the T cell receptor via interaction with APC peptide-MHC complexes and a second through interaction of CD28 with APC B7 ligands. Following activation, T cells up-regulate a host of other membrane-bound costimulatory molecules which can either promote or inhibit further T cell maturation and proliferation. In some cases, it is necessary to attenuate T cell activation to prevent deleterious inflammation, and inhibitory members of the B7/Butyrophilin family of ligands have evolved to balance the strong stimuli the activating B7 ligands confer. Human genetic association and in vitro studies have implicated one such ligand, BTNL2, in controlling inflammation at mucosal surfaces. Here we show that recombinant mouse BTNL2 modifies B7/CD28 signaling to promote expression of Foxp3, a transcription factor necessary for murine Treg development and function. BTNL2 blocks Akt-mediated inactivation of Foxo1, a transcription factor necessary for Foxp3 expression. Immunophenotyping and gene profiling reveal that BTNL2-induced Treg share many properties with natural Treg, and in vivo they suppress enteritis induced by mouse effector T cells. These findings describe a mechanism by which environmental antigen-driven formation of Treg may be orchestrated by APC expressing specific modulators of costimulatory signals. CD4+CD25- cells isolated from spleen were stimulated on plates coated with anti-mouse CD3 and human IgG (negative control), anti-mouse CD3, rB7-2, and IgG (positive control), and anti-mouse CD3, rB7-2, and rBTNL2 (experimental). Culturing was performed in duplicate for each condition.
Project description:Foxp3, a transcription factor of the forkhead/winged helix family, plays a unique role in the transcriptional control of regulatory CD4+CD25+ T (Treg) cells. The identification of potential target genes associated with the regulatory phenotype and the characterization of combinatorial interactions of transcription factors (TF) in promoter regions in genes regulated by Foxp3 has become important to understand the transcriptional control of Treg cells.
Project description:The epigenetic regulation of transcription factor genes is critical for T cell lineage specification. A specific methylation pattern within a conserved region of the lineage specifying transcription factor gene FOXP3, the Treg-specific demethylated region (TSDR), is restricted to regulatory T (Treg) cells and required for stable expression of FOXP3 and suppressive function. We analyzed the impact of hypomethylating agents 5-Aza-2`-deoxycytidine and Epigallocatechin-3-gallate (EGCG) on human CD4+CD25- T for generating Treg cell specific DNA methylation pattern within FOXP3-TSDR and inducing functional Treg cells. Gene expression, including lineage specifying transcription factors of the major T cell lineages and their leading cytokines, functional properties and global transcriptome changes were analyzed. 5-Aza-2`-deoxycytidine induced FOXP3-TSDR methylation and expression of Treg cell specific genes FOXP3 and LRRC32. Proliferation of 5-Aza-2´deoxycytidine treated cells was reduced, but they did not show suppressive function. Hypomethylation was not restricted to FOXP3-TSDR and expression of master transcription factors and leading cytokines of Th1 and Th17 cells were induced. EGCG induced global DNA hypomethylation to a lower degree than 5-Aza-2´deoxycitidine, but no relevant hypomethylation within FOXP3-TSDR or expression of Treg cell specific genes. Both DNMT inhibitors did not induce full functional human Treg cells. Although 5-Aza-2`-deoxycytidine treated cells phenotypically appeared to be Treg cells, they did not suppress proliferation of responder cells, which is an essential capability to be used in Treg cell transfer therapy. In this study we analyze the potency of the two hypomethylating agents 5-Aza-2`-deoxycytidine (5-Aza-dC) and Epigallocatechin-3-gallate (EGCG) for in vitro induction of functional Treg cell cells through generation of a specific methylation pattern within FOXP3-TSDR. We analyzed the expression of Treg cell specific genes and for their functional properties from CD4+CD25- T cells. 5-Aza-dC is a derivative of 5-Azacytidine. Both substances are inhibitors of DNA methyltransferases (DNMTs) and used for therapy of patients with myelodysplastic syndrome and acute myeloid leukaemia. In these patients, 5-Azacytidine has been reported to augment regulatory T cell expansion in blood. EGCG is the most abundant catechin of green tea and has been reported to have cardio protective, anti-cancer, anti-infective properties and protective effects on autoimmune diseases. EGCG has also been described as a potent inhibitor of DNMTs and to induce Foxp3 in Jurkat T cell line.
Project description:Differential gene transcription enables development and homeostasis in all animals and is regulated by two major classes of distal cis-regulatory DNA elements (CREs), enhancers and silencers. While enhancers have been thoroughly characterized, the properties and mechansisms of silencers remain largely unknown. By an unbiased genome-wide functional screen in Drosophila melanogaster S2 cells, we discover a class of silencers that bind one of three transcription factors (TFs) and are generally not included in chromatin-defined CRE catalogs, as they mostly lack detectable DNA accessibility. The silencer-binding TF CG11247, which we term Saft, safeguards cell fate decisions in vivo and functions via a highly-conserved domain we term ZAC and the corepressor G9a, independently of G9a’s H3K9-methyltransferase activity. Overall, our identification of silencers with unexpected properties and mechanisms has important implications for the understanding and future study of repressive CREs, as well as the functional annotation of animal genomes.
Project description:We investigated the transcriptome of closely related CD4+ T-cell population from healthy human donors to elucidate the processes that underly their specialized immune functions
Project description:H3K36me3 ChIP sequencing performed on circulating ex vivo isolated CD4+ Naive T cells under LINE1 RNA knock-down and control conditions
Project description:In HLA-B27/human beta-2m transgenic rat (B27-rats), the spontaneous development of a chronic inflammatory disorder closely resembling spondyloarthritis (SpA) is strongly correlated with high levels of HLA-B27/human beta-2m transgene expression and with aberrant function of dendritic cells (DCs). To dissect the mechanisms that could be involved in DCs dysfunction, we investigated the genes expression by transcriptomic analysis in DCs from B27 versus controls rats
Project description:T follicular helper (Tfh) cells constitute an essential cell type in the induction of antibodies. We report that CD4 T cells lacking Foxo1 almost uniformly became CXCR5int Tfh cells following immunization. Moreover, a Foxo1 loss-of-function complemented an Icos mutation allowing the appearance of Tfh cells along with follicular, class-switched B cells and IgG isotype anti-DNA antibodies. Similarly, FOXO1 deficient Tfh differentiation displayed a substantially reduced dependence on ICOSL. Functional and molecular analyses show that FOXO1 regulates Tfh differentiation through a broad program of gene expression exemplified by positive regulation of Icos and negative regulation of Bcl6. These results demonstrate that a key step in Tfh differentiation is the ICOS-initiated activation of the PI3K-AKT pathway resulting in the inactivation of FOXO1. Performed ChIP-seq analysis to examine the role of foxo1 in the development of Tfh cells
Project description:Recent developments in genomic sequencing technology have enabled comprehensive transcriptome analyses of single cells. In contrast, single cell proteomics analyses have been restricted to targeted analyses, for example using flow cytometry with GFP fusions or mass cytometry. Here, we performed global absolute protein quantification of single Xenopus laevis eggs using mass spectrometry-based proteomics. We quantified over 5800 proteins, thus representing the largest single cell proteome that has been characterized to date. Absolute protein amounts in single eggs are highly comparable, thus indicating a tight regulation of global protein abundance. Comparison between the single-cell proteome and transcriptome reveal poor expression correlation. Finally, we identified 439 proteins that significantly change in abundance during early embryogenesis. Many of these proteins do not show regulation at the transcript level. Altogether, our data reveal that the transcriptome is a poor indicator of the proteome and that protein levels are tightly controlled in Xenopus leavis eggs. RNA-seq in Xenopus laevis of 5 replicates of both single eggs and single embryos.