title: TLR3 drives IRF6-dependent IL-23p19 expression and p19/EBI3 heterodimer formation in keratinocytes.
abstract: Interferon regulatory factor (IRF) family members impart cell-type specificity to toll-like receptor (TLR) signalling, and we recently identified a role for IRF6 in TLR2 signalling in epithelial cells. TLR3 has a well-characterized role in wound healing in the skin, and here, we examined TLR3-dependent IRF6 functions in human keratinocytes. Primary keratinocytes responded robustly to the TLR3 agonist poly(IC) with upregulation of mRNAs for interferon-β (IFN-β), the interleukin-12 (IL-12) family member IL-23p19 and the chemokines IL-8 and chemokine (C-C motif) ligand 5 (CCL5). Silencing of IRF6 expression enhanced poly(IC)-inducible IFN-β mRNA levels and inhibited poly(IC)-inducible IL-23p19 mRNA expression in primary keratinocytes. Consistent with these data, co-transfection of IRF6 increased poly(IC)-inducible IL-23p19 promoter activity, but inhibited poly(IC)-inducible IFN-β promoter activity in reporter assays. Surprisingly, poly(IC) did not regulate IL-12p40 expression in keratinocytes, suggesting that TLR3-inducible IL-23p19 may have an IL-23-independent function in these cells. The only other IL-12 family member that was strongly poly(IC) inducible was EBI3, which has not been shown to heterodimerize with IL-23p19. Both co-immunoprecipitation and proximity ligation assays revealed that IL-23p19 and EBI3 interact in cells. Co-expression of IL-23p19 and EBI3, as compared with IL-23p19 alone, resulted in increased levels of secreted IL-23p19, implying a functional role for this heterodimer. In summary, we report that IRF6 regulates a subset of TLR3 responses in human keratinocytes, including the production of a novel IL-12 family heterodimer (p19/EBI3). We propose that the TLR3-IRF6-p19/EBI3 axis may regulate keratinocyte and/or immune cell functions in the context of cell damage and wound healing in the skin.
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Divya
authors: D
authors: Ramnath
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Kathryn
authors: K
authors: Tunny
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Daniel M
authors: DM
authors: Hohenhaus
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Claire M
authors: CM
authors: Pitts
authors: Diamantina Institute, The University of Queensland, Brisbane, Queensland, Australia.
authors: Anne-Sophie
authors: AS
authors: Bergot
authors: Centre for Immunology, Burnet Institute, Melbourne, Victoria, Australia.
authors: P Mark
authors: PM
authors: Hogarth
authors: Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.
authors: John A
authors: JA
authors: Hamilton
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Ronan
authors: R
authors: Kapetanovic
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|Dermatology Research Centre, The University of Queensland, School of Medicine, Translational Research Institute, Brisbane, Queensland, Australia.
authors: Richard A
authors: RA
authors: Sturm
authors: Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia.|Melbourne Dental School and Oral Health Cooperative Research Centre, The University of Melbourne, Parkville, Victoria, Australia.|Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia.
authors: Glen M
authors: GM
authors: Scholz
authors: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.|IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
authors: Matthew J
authors: MJ
authors: Sweet
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D015870:Gene Expression / Q000187:drug effects; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D050835:Interferon Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D053760:Interleukin-23 Subunit p19 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007378:Interleukins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D061986:MCF-7 Cells; D018613:Microscopy, Confocal; D015778:Minor Histocompatibility Antigens; D011070:Poly I-C / Q000494:pharmacology; D011485:Protein Binding; D055503:Protein Multimerization; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051196:Toll-Like Receptor 3 / Q000819:agonists / Q000378:metabolism*
chemical_list: C097732:EBI3 protein, human; C109803:IRF6 protein, human; D050835:Interferon Regulatory Factors; D053760:Interleukin-23 Subunit p19; D007378:Interleukins; D015778:Minor Histocompatibility Antigens; D051196:Toll-Like Receptor 3; D011070:Poly I-C