Project description:Here, we show that the activity of the tumor suppressor p53 in the metazoan C. elegans switches organismal development between reproductive growth and dormancy by responding to nutrient availability signaled by the cytokine, ILC-17.1. ILC-17.1-dependent repression of the C. elegans p53 ortholog CEP-1 is required for larval growth and development; ILC-17.1 deficiency activates CEP-1/p53 in post-embryonically dividing progenitor blast cells, decreases glucose utilization and cytochrome C levels, upregulates cell cycle inhibitors, and causes larvae to arrest as stress-resistant, quiescent dauers.
Project description:Metazoan growth and development requires the coordination of cell cycle progression and metabolism with nutrient availability1-3. Here, we show that in C. elegans, amphid neurons regulate the animals’ developmental decision to continue reproductive growth or arrest as quiescent dauer larvae in response to food, by controlling the activity of C. elegans p53-like ortholog, CEP-1. Specifically, upon food availability, larval neurons secrete a mammalian IL-17 ortholog, ILC-17.1, and ILC-17.1 signaling is needed for C. elegans to progress through development into reproductive adults. ILC-17.1 deficiency activates CEP-1/p53 in larval blast cells, and causes larvae to arrest as stress-resistant, quiescent dauers by activating DAF-16/FOXO, decreasing cytochrome C levels, decreasing glucose utilization and upregulating cell cycle inhibitors. Increasing ILC-17.1 levels represses CEP-1/p53 and promotes anabolic growth, but also inhibits apoptosis upon genotoxic stress. IL-17 also represses p53 in human epithelial cells. These studies describe a role for the tumor suppressor p53-like proteins in controlling developmental quiescence of a metazoan in response to neuronal activity and immunometabolic signals and are relevant to our understanding of neuroimmune mechanisms in cancer. This novel role for p53-like proteins in C. elegans supports the argument that their developmental function was a main driving force in their evolution4,5.
Project description:IL-17 mediates immune protection from fungi and bacteria as well as it promotes autoimmune pathologies. However, the regulation of the signal transduction from the IL-17 receptor (IL-17R) remained elusive. We developed a novel mass spectrometry-based approach to identify components of the IL-17R complex followed by analysis of their roles using reverse genetics. Besides the identification of LUBAC as an important signal transducing component of IL-17R, we established that IL-17 signaling is regulated by a robust negative feedback loop mediated by TBK1 and IKKε. These kinases terminate IL-17 signaling by phosphorylating the adaptor ACT1 leading to the release of the essential ubiquitin ligase TRAF6 from the complex. NEMO recruits both kinases to the IL-17R complex, documenting that NEMO has an unprecedented negative function in IL-17 signaling, distinct from its role in NF-κB activation. Our study provides a comprehensive view of the molecular events of the IL-17 signal transduction and its regulation.
Project description:Interleukin-17A (IL-17A) is a key mediator of protective immunity to yeast and bacterial infections but also drives the pathogenesis of several autoimmune diseases, such as psoriasis or psoriatic arthritis. Here, we show that the tetra-transmembrane protein CMTM4 is a subunit of the IL-17 receptor (IL-17R). CMTM4 constitutively associated with IL-17R subunit C (IL-17RC) to mediate its stability, posttranslational modification, and plasma membrane localization. Both mouse and human cell lines deficient in CMTM4 were largely unresponsive to IL-17A, due to their inability to assemble the IL-17 receptor signaling complex. Accordingly, CMTM4-deficient mice were largely resistant to experimental psoriasis. Collectively, our data identified CMTM4 as an essential component of the IL-17 receptor and a potential therapeutic target for treating IL-17-mediated autoimmune diseases.
Project description:The conventional notion of “immune privilege” of the brain has been revised to accommodate its infiltration, at steady state, by immune cells that participate in normal neurophysiology (Louveau, Trends Immunol 2015; Kipnis science 2016; Filiano, Nat Rev Neurosciences 2017). Surprisingly, such neuroimmune functions have been linked to “pro-inflammatory” cytokines like IL-4 or IFN-α, shown to control behavioural and social cognition (Derecki, JEM 2010; Filiano, Nature 2016). Here we identify a pro-cognitive role for IL-17 in short-term memory that derives from a previously unknown meningeal-resident γδ T cell subset. This was mostly composed of foetal thymic-derived Vγ6+ T cells, found in the meninges at birth and persisting throughout life, where they were strikingly polarized towards IL-17 production. In fact, γδ T cells were the overwhelming source of meningeal IL-17, whereas IFN-γ was mostly provided by T cells. To assess whether the constitutive production of IL-17 by γδ T cells influenced the cognitive performance of mice, we tested TCRδ-/-, IL-17-/- and respective WT littermate control mice in classical learning paradigms. We observed that mice deficient either for γδ T cells or IL-17 displayed impaired short-term memory in the Y maze paradigm, while retaining normal long-term spatial memory in the Morris water maze. A detailed proteomics analysis of the hippocampus provided mechanistic insight into reduced plasticity of the glutamatergic synapses in the absence of IL-17, which associated with impaired Long Term Potentiation (LTP). Conversely, IL-17 enhanced glial cell production of Brain Derived Neurotropic Factor (BDNF), whose exogenous provision rescued the LTP defect of IL-17-/- animals. Altogether, our data demonstrate that foetal-derived γδ T cells populate the brain meninges where they regulate synaptic plasticity and short-term memory through a non-inflammatory IL-17-dependent mechanism.
Project description:Cytokines such as TNF-alpha and IL-1beta are known for their contribution to inflammatory processes in liver . In contrast, the cytokine IL-17 has not yet been assigned a role in liver diseases. IL-17 can cooperate with TNF-alpha to induce a synergistic response on several target genes in different cell lines, but no data exist for primary hepatocytes. To enhance our knowledge on the impact of IL-17 alone and combined with TNF-alpha in primary murine hepatocytes a comprehensive microarray study was designed. IL-1beta was included as this cytokine is suggested to act in a similar manner as the combination of TNF-alpha and IL-17, especially with respect to its role in mRNA stabilization. Results: The present microarray analysis demonstrates that primary murine hepatocytes responded to IL-17 stimulation by upregulation of chemokines and genes, which are functionally responsible to increase and sustain inflammation. Cxcl2, Nfkbiz and Zc3h12a were strongly induced, whereas the majority of the genes were only very moderately upregulated. Promoter analysis revealed involvement of NF-kappaB in the activation of many genes. Combined stimulation of TNF-alpha/IL-17 resulted in enhanced induction of gene expression, but significantly synergistic effects could be applied only to a few genes, such as Nfkbiz, Cxcl2, Zc3h12 and Steap4. Comparison of the gene expression profile obtained after stimulation of TNF-alpha/IL-17 versus IL-1 proposed a IL-1beta-like effect of the latter cytokine combination. Moreover, evidence was provided that modulation of mRNA stability may be a major mechanism by which IL-17 regulates gene expression in primary hepatocytes. This assumption was exemplarily proven for Nfkbiz mRNA for the first time in hepatocytes. Our studies also suggest that RNA stability can partially be correlated to the existence of AU rich elements, but further mechanisms like the RNase-activity of the upregulated Zc3h12a have to be considered. Conclusions: Our microarray analysis gives new insights in IL-17 induced gene expression in primary hepatocytes highlighting the crosstalk with the NF-kappaB signalling pathway. Gene expression profile suggests IL-17 a role in sustaining liver inflammatory processes most likely by RNA stabilization. Altogether, our results provide evidence that IL-17 alone and in concert with TNF-alpha may play a role in inflammatory liver diseases. Primary murine hepatocytes of three animals stimulated for 1 or 4h by TNF-alpha, IL-1beta, IL-17 or TNF-alpha followed by IL-17 were used for microarray analysis.
Project description:Cytokines such as TNF-alpha and IL-1beta are known for their contribution to inflammatory processes in liver . In contrast, the cytokine IL-17 has not yet been assigned a role in liver diseases. IL-17 can cooperate with TNF-alpha to induce a synergistic response on several target genes in different cell lines, but no data exist for primary hepatocytes. To enhance our knowledge on the impact of IL-17 alone and combined with TNF-alpha in primary murine hepatocytes a comprehensive microarray study was designed. IL-1beta was included as this cytokine is suggested to act in a similar manner as the combination of TNF-alpha and IL-17, especially with respect to its role in mRNA stabilization. Results: The present microarray analysis demonstrates that primary murine hepatocytes responded to IL-17 stimulation by upregulation of chemokines and genes, which are functionally responsible to increase and sustain inflammation. Cxcl2, Nfkbiz and Zc3h12a were strongly induced, whereas the majority of the genes were only very moderately upregulated. Promoter analysis revealed involvement of NF-kappaB in the activation of many genes. Combined stimulation of TNF-alpha/IL-17 resulted in enhanced induction of gene expression, but significantly synergistic effects could be applied only to a few genes, such as Nfkbiz, Cxcl2, Zc3h12 and Steap4. Comparison of the gene expression profile obtained after stimulation of TNF-alpha/IL-17 versus IL-1 proposed a IL-1beta-like effect of the latter cytokine combination. Moreover, evidence was provided that modulation of mRNA stability may be a major mechanism by which IL-17 regulates gene expression in primary hepatocytes. This assumption was exemplarily proven for Nfkbiz mRNA for the first time in hepatocytes. Our studies also suggest that RNA stability can partially be correlated to the existence of AU rich elements, but further mechanisms like the RNase-activity of the upregulated Zc3h12a have to be considered. Conclusions: Our microarray analysis gives new insights in IL-17 induced gene expression in primary hepatocytes highlighting the crosstalk with the NF-kappaB signalling pathway. Gene expression profile suggests IL-17 a role in sustaining liver inflammatory processes most likely by RNA stabilization. Altogether, our results provide evidence that IL-17 alone and in concert with TNF-alpha may play a role in inflammatory liver diseases.