Project description:The IL-17 receptor adaptor molecule Act1, an RNA binding protein, plays a critical role in IL-17-mediated cancer progression. Here we report a novel mechanism for how IL-17/Act1 induces chemoresistance by modulating redox homeostasis through epitranscriptomic regulation of antioxidant RNA metabolism. Transcriptome-wide mapping of direct Act1-RNA interactions revealed that Act1 binds to the 5'UTR of antioxidant mRNAs and Wilms' tumor 1-associating protein (WTAP), a key regulator in m6A methyltransferase complex. Strikingly, Act1's binding sites are located in proximity to m6A modification sites, which allows Act1 to promote the recruitment of elF3G for cap-independent translation. Loss of Act1’s RNA binding activity or Wtap knockdown abolished IL-17-induced m6A modification and translation of Wtap and antioxidant mRNAs, indicating a feedforward mechanism of Act1-WTAP loop. We then developed antisense oligonucleotides (Wtap ASO) that specifically disrupts Act1’s binding to Wtap mRNA, abolishing IL-17/Act1-WTAP-mediated antioxidant protein production during chemotherapy. Wtap ASO substantially increased the antitumor efficacy of cisplatin, demonstrating a potential therapeutic strategy for chemoresistance.
Project description:The IL-17 receptor adaptor molecule Act1, an RNA binding protein, plays a critical role in IL-17-mediated cancer progression. Here we report a novel mechanism for how IL-17/Act1 induces chemoresistance by modulating redox homeostasis through epitranscriptomic regulation of antioxidant RNA metabolism. Transcriptome-wide mapping of direct Act1-RNA interactions revealed that Act1 binds to the 5'UTR of antioxidant mRNAs and Wilms' tumor 1-associating protein (WTAP), a key regulator in m6A methyltransferase complex. Strikingly, Act1's binding sites are located in proximity to m6A modification sites, which allows Act1 to promote the recruitment of elF3G for cap-independent translation. Loss of Act1’s RNA binding activity or Wtap knockdown abolished IL-17-induced m6A modification and translation of Wtap and antioxidant mRNAs, indicating a feedforward mechanism of Act1-WTAP loop. We then developed antisense oligonucleotides (Wtap ASO) that specifically disrupts Act1’s binding to Wtap mRNA, abolishing IL-17/Act1-WTAP-mediated antioxidant protein production during chemotherapy. Wtap ASO substantially increased the antitumor efficacy of cisplatin, demonstrating a potential therapeutic strategy for chemoresistance.
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:Our study indicates that lncRNA TRAF3IP2-AS1 serving as a negative regulator of Act1 transcriptional expression and IL-17 signaling pathway activity,recruits SRSF10 to downregulate the transcription of IRF1, which is itself a transcriptional factor for Act1. And the psoriasis-susceptible variant A4165G of TRAF3IP2-AS1 is a gain-of-function mutant that binds more strongly than the wild-type form to SRSF10. It means that TRAF3IP2-AS1 or SRSF10 may be a good target for the treatment of human IL-17-related autoimmune diseases.
Project description:TRAF3IP2 is a candidate psoriasis susceptibility gene encoding Act1, a ubiquitin ligase that couples the IL-17 receptor to downstream signaling pathways. We investigated the role of Act1 in keratinocyte responses to IL-17 using a tetracycline inducible shRNA targeting TRAF3IP2. Tet exposure for seven days effectively silenced TRAF3IP2 mRNA and Act1 protein, resulting in 761 genes with significant changes in expression (495 down, 266 up, >1.5-fold, p<0.05). Gene Ontology analysis revealed that genes affected by TRAF3IP2 silencing are involved in epidermal differentiation, with early differentiation genes (KRT1, KRT10, DSC1, DSG1) being downregulated and late differentiation genes (SPRR2, SPRR3, LCE3) being upregulated. AP1 binding sites were enriched upstream of genes up-regulated by TRAF3IP2 silencing. Correspondingly, nuclear expression of FosB and Fra1 was increased in TRAF3IP2-silenced cells. Many genes involved in host defense were induced by IL-17 in a TRAF3IP2-dependent fashion. Inflammatory differentiation conditions (serum addition for 4 days postconfluence) markedly amplified these IL-17 responses, while increasing basal levels and TRAF3IP2 silencing-dependent upregulation of late differentiation genes. These findings suggest that TRAF3IP2 may alter both epidermal homeostasis and keratinocyte defense responses to influence psoriasis risk.
Project description:Interleukin-17 (IL-17) is essential in host defense against extracellular bacteria and fungi, especially at mucosal sites, but it also contributes significantly to inflammatory and autoimmune disease pathologies. Binding of IL-17 to its receptor leads to recruitment of the adaptor protein CIKS/Act1 via heterotypic association of their respective SEFIR domains and to activation of the transcription factor NF-kB; it is not known whether CIKS and/or NF-kB are required for all gene induction events. Here we report that CIKS is essential for all IL-17 induced immediate-early genes in primary mouse embryo fibroblasts, while NF-kB is profoundly involved. We also identify a novel sub-domain in the N-terminus of CIKS that is essential for IL-17-mediated NF-kB activation. This domain is both necessary and sufficient for the interaction between CIKS and TRAF6, an adaptor required for NF-kB activation. The ability of decoy peptides to block this interaction may provide a new therapeutic strategy for intervention in IL-17-driven autoimmune and inflammatory diseases. Keywords: strain comparisons strain comparisons
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.
Project description:Interleukin-17 (IL-17) is essential in host defense against extracellular bacteria and fungi, especially at mucosal sites, but it also contributes significantly to inflammatory and autoimmune disease pathologies. Binding of IL-17 to its receptor leads to recruitment of the adaptor protein CIKS/Act1 via heterotypic association of their respective SEFIR domains and to activation of the transcription factor NF-kB; it is not known whether CIKS and/or NF-kB are required for all gene induction events. Here we report that CIKS is essential for all IL-17 induced immediate-early genes in primary mouse embryo fibroblasts, while NF-kB is profoundly involved. We also identify a novel sub-domain in the N-terminus of CIKS that is essential for IL-17-mediated NF-kB activation. This domain is both necessary and sufficient for the interaction between CIKS and TRAF6, an adaptor required for NF-kB activation. The ability of decoy peptides to block this interaction may provide a new therapeutic strategy for intervention in IL-17-driven autoimmune and inflammatory diseases. Keywords: strain comparisons