Project description:Interleukin-23 (IL-23) is a pro-inflammatory cytokine required for the pathogenicity of T helper 17 (Th17) cells but the molecular mechanisms governing this process remain unclear. We identified the transcription factor Blimp-1 (Prdm1) as a key IL-23-induced factor that drove the inflammatory function of Th17 cells. In contrast to thymic deletion of Blimp-1, which causes T cell development defects and spontaneous autoimmunity, peripheral deletion of this transcription factor resulted in reduced Th17 activation and reduced severity of autoimmune encephalomyelitis. Furthermore, genome wide occupancy and overexpression studies in Th17 cells revealed that Blimp-1 co-localized with transcription factors RORγt, STAT-3 and p300 at the Il23r, Il17a/f and Csf2 cytokine loci to enhance their expression. Blimp-1 also directly bound to and repressed cytokine loci Il2 and Bcl6. Taken together, our results demonstrate that Blimp-1 is an essential transcription factor downstream of IL-23 that acts in concert with RORγt to activate the Th17 inflammatory program. Genome-wide binding analysis of Blimp1 from in vitro generated T effector and regulatory cells
Project description:Interleukin 23 (IL-23) triggers pathogenic features in pro-inflammatory, IL-17-secreting T cells (Th17 and Tγδ17) that play a key role in the development of inflammatory diseases. However, the IL-23 signaling cascade remains largely undefined. Here we used quantitative phosphoproteomics to characterize IL-23 signaling in primary murine Th17 cells. We quantified 6,888 phosphorylation sites in Th17 cells, and found 168 phosphorylations regulated upom IL-23 stimulation. IL-23 increased the phosphorylation of the myosin regulatory light chain (RLC), an actomyosin contractibility marker, in Th17 and Tγδ cells. IL-23-induced RLC phosphorylation required JAK2 and ROCK catalytic activity, and the study of the IL-23/ROCK axis revealed an unexpected role of IL-23 in the migration of Tγδ17 and Th17 cells. Moreover, pharmacological inhibition of ROCK reduced Tγδ17 recruitment to inflamed skin upon challenge with inflammatory agent Imiquimod. This work: i) provides new insights into phosphorylation networks that control Th17 cells, ii) widely expands the current knowledge on IL-23 signaling, and iii) contributes to the increasing list of immune cells subsets characterized by global phosphoproteomic approaches.
Project description:Interleukin-23 (IL-23) is a pro-inflammatory cytokine required for the pathogenicity of T helper 17 (Th17) cells but the molecular mechanisms governing this process remain unclear. We identified the transcription factor Blimp-1 (Prdm1) as a key IL-23-induced factor that drove the inflammatory function of Th17 cells. In contrast to thymic deletion of Blimp-1, which causes T cell development defects and spontaneous autoimmunity, peripheral deletion of this transcription factor resulted in reduced Th17 activation and reduced severity of autoimmune encephalomyelitis. Furthermore, genome wide occupancy and overexpression studies in Th17 cells revealed that Blimp-1 co-localized with transcription factors RORγt, STAT-3 and p300 at the Il23r, Il17a/f and Csf2 cytokine loci to enhance their expression. Blimp-1 also directly bound to and repressed cytokine loci Il2 and Bcl6. Taken together, our results demonstrate that Blimp-1 is an essential transcription factor downstream of IL-23 that acts in concert with RORγt to activate the Th17 inflammatory program.
Project description:Th17 cells are highly proinflammatory cells that are critical for clearing extracellular pathogens like fungal infections and for induction of multiple autoimmune diseases1. IL-23 plays a critical role in stabilizing and endowing Th17 cells with pathogenic effector functions2. Previous studies have shown that IL-23 signaling reinforces the Th17 phenotype by increasing expression of IL-23 receptor (IL-23R)3. However, the precise molecular mechanism by which IL-23 sustains the Th17 response and induces pathogenic effector functions has not been elucidated. Here, we used unbiased transcriptional profiling of developing Th17 cells to construct a model of their signaling network and identify major nodes that regulate Th17 development. We identified serum glucocorticoid kinase-1 (SGK1), as an essential node downstream of IL-23 signaling, critical for regulating IL-23R expression and for stabilizing the Th17 cell phenotype by deactivation of Foxo1, a direct repressor of IL-23R expression. A serine-threonine kinase homologous to AKT4, SGK1 has been associated with cell cycle and apoptosis, and has been shown to govern Na+ transport and homeostasis5, 6 7, 8. We here show that a modest increase in salt (NaCl) concentration induces SGK1 expression, promotes IL-23R expression and enhances Th17 cell differentiation in vitro and in vivo, ultimately accelerating the development of autoimmunity. The loss of SGK1 resulted in abrogation of Na+-mediated Th17 differentiation in an IL-23-dependent manner. These data indicate that SGK1 is a critical regulator for the induction of pathogenic Th17 cells and provides a molecular insight by which an environmental factor such as a high salt diet could trigger Th17 development and promote tissue inflammation. Th17 cells; comparing Sgk1-/- to WT
Project description:Th17 cells are highly proinflammatory cells that are critical for clearing extracellular pathogens like fungal infections and for induction of multiple autoimmune diseases1. IL-23 plays a critical role in stabilizing and endowing Th17 cells with pathogenic effector functions2. Previous studies have shown that IL-23 signaling reinforces the Th17 phenotype by increasing expression of IL-23 receptor (IL-23R)3. However, the precise molecular mechanism by which IL-23 sustains the Th17 response and induces pathogenic effector functions has not been elucidated. Here, we used unbiased transcriptional profiling of developing Th17 cells to construct a model of their signaling network and identify major nodes that regulate Th17 development. We identified serum glucocorticoid kinase-1 (SGK1), as an essential node downstream of IL-23 signaling, critical for regulating IL-23R expression and for stabilizing the Th17 cell phenotype by deactivation of Foxo1, a direct repressor of IL-23R expression. A serine-threonine kinase homologous to AKT4, SGK1 has been associated with cell cycle and apoptosis, and has been shown to govern Na+ transport and homeostasis5, 6 7, 8. We here show that a modest increase in salt (NaCl) concentration induces SGK1 expression, promotes IL-23R expression and enhances Th17 cell differentiation in vitro and in vivo, ultimately accelerating the development of autoimmunity. The loss of SGK1 resulted in abrogation of Na+-mediated Th17 differentiation in an IL-23-dependent manner. These data indicate that SGK1 is a critical regulator for the induction of pathogenic Th17 cells and provides a molecular insight by which an environmental factor such as a high salt diet could trigger Th17 development and promote tissue inflammation. Effects of NaCl on Th17 differentiation
Project description:Interleukin (IL)-17-producing T helper (Th17) cells are crucial for host defense against extracellular microbes and pathogenesis of autoimmune diseases. Here we show that the AP-1 transcription factor JunB is required for Th17 cell development. Junb-deficient CD4+ T cells are able to develop in vitro into various helper T subsets except Th17. The RNA-seq transcriptome analysis reveals that JunB is crucial for the Th17-specific gene expression program. Junb-deficient mice are completely resistant to experimental autoimmune encephalomyelitis, a Th17-mediated inflammatory disease, and naive T helper cells from such mice fail to differentiate into Th17 cells. JunB appears to activate Th17 signature genes by forming a heterodimer with BATF, another AP-1 factor essential for Th17 differentiation. The mechanism whereby JunB controls Th17 cell development likely involves activation of the genes for the Th17 lineage-specifying orphan receptors RORt and ROR and reduced expression of Foxp3, a transcription factor known to antagonize RORt function.
Project description:To understand the mechanisms through which JunB regulates Tregs-mediated immune regulation, we examined the global gene expression profiles in the JunB WT and KO Tregs by performing RNA sequencing (RNA-seq) analysis.
Project description:Th17 cells are highly proinflammatory cells that are critical for clearing extracellular pathogens like fungal infections and for induction of multiple autoimmune diseases1. IL-23 plays a critical role in stabilizing and endowing Th17 cells with pathogenic effector functions2. Previous studies have shown that IL-23 signaling reinforces the Th17 phenotype by increasing expression of IL-23 receptor (IL-23R)3. However, the precise molecular mechanism by which IL-23 sustains the Th17 response and induces pathogenic effector functions has not been elucidated. Here, we used unbiased transcriptional profiling of developing Th17 cells to construct a model of their signaling network and identify major nodes that regulate Th17 development. We identified serum glucocorticoid kinase-1 (SGK1), as an essential node downstream of IL-23 signaling, critical for regulating IL-23R expression and for stabilizing the Th17 cell phenotype by deactivation of Foxo1, a direct repressor of IL-23R expression. A serine-threonine kinase homologous to AKT4, SGK1 has been associated with cell cycle and apoptosis, and has been shown to govern Na+ transport and homeostasis5, 6 7, 8. We here show that a modest increase in salt (NaCl) concentration induces SGK1 expression, promotes IL-23R expression and enhances Th17 cell differentiation in vitro and in vivo, ultimately accelerating the development of autoimmunity. The loss of SGK1 resulted in abrogation of Na+-mediated Th17 differentiation in an IL-23-dependent manner. These data indicate that SGK1 is a critical regulator for the induction of pathogenic Th17 cells and provides a molecular insight by which an environmental factor such as a high salt diet could trigger Th17 development and promote tissue inflammation.