Project description:Targeting histone/protein deacetylase (HDAC)-6, -9, or Sirtuin-1 (Sirt1) augments the suppressive functions of Foxp3+ T regulatory (Treg) cells, but it is unclear if this involves different mechanisms, such that combined inhibition would be beneficial. We compared the suppressive functions of Tregs from wild-type C57BL/6 mice or mice with global (HDAC6-/-, HDAC9-/-, dual HDAC6/9-/-) or conditional deletion (CD4-Cre or Foxp3-Cre and floxed Sirt1; GSE26425) alone, or after treatment with isoform-selective HDAC inhibitors (HDACi). We found the heat shock response was crucial in mediating the effects of HDAC6, but not Sirt1 inhibition. Furthermore, while HDAC6, HDAC9 and Sirt1 all deacetylate Foxp3, each has diverse effects on Foxp3 transcription, and loss of HDAC9 is associated with stabilization of Stat5 acetylation and its transcriptional activity. Targeting different HDAC can increase Treg function by multiple and additive mechanisms, indicating the therapeutic potential for combinations of HDACi in the management of autoimmunity and alloresponses post-transplant. RNA from three independent samples of magnetically separated CD4+CD25+ Treg of HDAC9-/- mice, compared to wild type (C57BL/6) control.
Project description:Sirtuin-1 (Sirt1), a class III histone/protein deacetylase is central to cellular metabolism, stress responses and aging, but its contributions to various host immune functions have been little investigated. To study the role of Sirt1 in T-cell functions, we undertook targeted deletions by mating mice with a floxed Sirt1 gene to mice expressing CD4-cre or Foxp3-cre recombinase, respectively. We found that Sirt1 deletion left conventional T-effector cell activation, proliferation and cytokine production largely unaltered. However, Sirt1 targeting promoted the expression and acetylation of Foxp3, a key transcription factor in T-regulatory (Treg) cells, and increased Treg suppressive functions in vitro and in vivo. Consistent with these data, mice with targeted deletions of Sirt1 in either CD4+ T-cells or Foxp3+ Treg cells exhibited prolonged survival of MHC-mismatched cardiac allografts. Allografts in Sirt1 targeted recipients showed long-term preservation of myocardial histology and infiltration by Foxp3+ Treg cells. Comparable results were seen in wild-type allograft recipients treated with Sirt1 inhibitors, such as EX-527 and splitomicin. Hence, Sirt1 may inhibit Treg functions and its targeting may have therapeutic value in autoimmunity and transplantation. RNA from three independent samples from magnetically separated CD4+CD25+ Treg of Sirt1 knock out, compared to wild type (C57BL6) control
Project description:Targeting histone/protein deacetylase (HDAC)-6, -9, or Sirtuin-1 (Sirt1) augments the suppressive functions of Foxp3+ T regulatory (Treg) cells, but it is unclear if this involves different mechanisms, such that combined inhibition would be beneficial. We compared the suppressive functions of Tregs from wild-type C57BL/6 mice or mice with global (HDAC6-/-, HDAC9-/-, dual HDAC6/9-/-) or conditional deletion (CD4-Cre or Foxp3-Cre and floxed Sirt1; GSE26425) alone, or after treatment with isoform-selective HDAC inhibitors (HDACi). We found the heat shock response was crucial in mediating the effects of HDAC6, but not Sirt1 inhibition. Furthermore, while HDAC6, HDAC9 and Sirt1 all deacetylate Foxp3, each has diverse effects on Foxp3 transcription, and loss of HDAC9 is associated with stabilization of Stat5 acetylation and its transcriptional activity. Targeting different HDAC can increase Treg function by multiple and additive mechanisms, indicating the therapeutic potential for combinations of HDACi in the management of autoimmunity and alloresponses post-transplant.
Project description:Sirtuin-1 (Sirt1), a class III histone/protein deacetylase is central to cellular metabolism, stress responses and aging, but its contributions to various host immune functions have been little investigated. To study the role of Sirt1 in T-cell functions, we undertook targeted deletions by mating mice with a floxed Sirt1 gene to mice expressing CD4-cre or Foxp3-cre recombinase, respectively. We found that Sirt1 deletion left conventional T-effector cell activation, proliferation and cytokine production largely unaltered. However, Sirt1 targeting promoted the expression and acetylation of Foxp3, a key transcription factor in T-regulatory (Treg) cells, and increased Treg suppressive functions in vitro and in vivo. Consistent with these data, mice with targeted deletions of Sirt1 in either CD4+ T-cells or Foxp3+ Treg cells exhibited prolonged survival of MHC-mismatched cardiac allografts. Allografts in Sirt1 targeted recipients showed long-term preservation of myocardial histology and infiltration by Foxp3+ Treg cells. Comparable results were seen in wild-type allograft recipients treated with Sirt1 inhibitors, such as EX-527 and splitomicin. Hence, Sirt1 may inhibit Treg functions and its targeting may have therapeutic value in autoimmunity and transplantation.
Project description:Regulatory T cells (Tregs) are responsible for limiting autoimmunity and chronic inflammation. Foxp3 is a transcription factor that acts as a master regulator of Treg development and function. A serendipitous observation led to the realization that a well-characterized Foxp3gfp reporter mouse, which expresses an N-terminal GFP-Foxp3 fusion protein, is a hypomorph that causes profoundly accelerated autoimmune diabetes on a NOD background. Although natural Treg development and in vitro function is not significantly altered in Foxp3gfp NOD and C57BL/6 mice, Treg fitness function in inflammatory environments is perturbed and TGF?-induced Treg development reduced. Foxp3gfpis unable to interact with the histone acetyltransferase Tip60, the histone deacetylase HDAC7, and the Ikaros family zinc finger 4, Eos, which leads to reduced Foxp3 acetylation and enhanced K48-linked polyubiquitylation. Collectively this leads to an altered transcriptional landscape and reduced Foxp3-mediated gene repression, notably at the hallmark IL-2 promoter. Loss of controlled Foxp3-driven epigenetic modification leads to Treg insufficiency that causes autoimmunity in prone environments. 16 samples overall split between 2 genotypes (wild type and Foxp3 knock in) and two cell types (Tregs and Tconv)
Project description:Regulatory T cells (Tregs) are responsible for limiting autoimmunity and chronic inflammation. Foxp3 is a transcription factor that acts as a master regulator of Treg development and function. A serendipitous observation led to the realization that a well-characterized Foxp3gfp reporter mouse, which expresses an N-terminal GFP-Foxp3 fusion protein, is a hypomorph that causes profoundly accelerated autoimmune diabetes on a NOD background. Although natural Treg development and in vitro function is not significantly altered in Foxp3gfp NOD and C57BL/6 mice, Treg fitness function in inflammatory environments is perturbed and TGFβ-induced Treg development reduced. Foxp3gfpis unable to interact with the histone acetyltransferase Tip60, the histone deacetylase HDAC7, and the Ikaros family zinc finger 4, Eos, which leads to reduced Foxp3 acetylation and enhanced K48-linked polyubiquitylation. Collectively this leads to an altered transcriptional landscape and reduced Foxp3-mediated gene repression, notably at the hallmark IL-2 promoter. Loss of controlled Foxp3-driven epigenetic modification leads to Treg insufficiency that causes autoimmunity in prone environments.
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:Natural CD4+FOXP3+ regulatory T (Treg) cells constitute a unique T-cell lineage that plays a pivotal role in maintaining immune homeostasis and immune tolerance. Recent studies provide evidence for the heterogeneity and plasticity of the Treg cell lineage. However, the fate of human Treg cells after loss of FOXP3 expression and the underlying epigenetic mechanisms remain to be fully elucidated. Here, we compared gene expression profiles and histone methylation status on two histone H3 lysine residues (H3K4me3 and H3K27me3) of expanded FOXP3+ and corresponding FOXP3-losing Treg cells. DGE assay showed that human Treg cells down-regulated Treg signature genes, whereas up-regulated a set of Th lineages-associated genes, especially for Th2, such as GATA3, GFI1 and IL13, after in vitro expansion. Furthermore, we found that reprogramming of Treg cells was associated with histone modifications, as shown by decreased abundance of permissive H3K4me3 within down-regulated Treg signature genes, such as FOXP3, CTLA4 and LRRC32 loci, although with no significant changes in H3K27me3 modification. Thus, our results indicate that human Treg cells could convert into a Th-like cells upon in vitro expansion, displaying a gene expression signature dominated by Th2 lineage associated genes, and the histone methylation might contribute to such conversion. Genome-wide analysis of histone H3 K4 and K27 trimethylation in expanded human FOXP3+ Treg cells and FOXP3-losing Treg cells