title: Tumor necrosis factor α-mediated induction of interleukin 17C in human keratinocytes is controlled by nuclear factor κB.
abstract: IL-17C is a member of the IL-17 family of cytokines. The expression of IL-17C has been demonstrated to be strongly induced by TNFα in human keratinocytes, and recently the level of IL-17C was found to be increased in the inflammatory skin disease psoriasis. However, little is known about the molecular mechanisms involved in the regulation of IL-17C. Here, we show that pretreatment of cultured human keratinocytes with the inhibitor of κB kinase 2 inhibitor, SC-514, resulted in a significant reduction in both IL-17C mRNA and protein expression, indicating the significance of this pathway in the regulation of IL-17C. NF-κB binding sites were identified upstream from the IL-17C gene, and by electrophoretic mobility shift assay NF-κB was shown to bind to all three identified binding sites. Moreover, NF-κB binding to these sites was inducible by TNFα. Supershift analysis revealed binding of the NF-κB subunits p65 and p50 to all three NF-κB binding sites. To determine the contribution of NF-κB in IL-17C expression, we conducted luciferase gene reporter experiments and demonstrated that a 3204-bp promoter fragment of IL-17C containing three putative NF-κB binding sites was strongly activated by TNFα. Interestingly, mutations of the three NF-κB binding sites revealed that one specific NF-κB binding site was crucial for the TNFα-mediated IL-17C induction because mutation of this specific site completely abolished TNFα-induced IL-17C promoter activation. We conclude that the activation of NF-κB (p65/p50) is crucial for the TNFα-induced stimulation of IL-17C expression in human keratinocytes.
authors.affiliation: Department of Dermatology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark. claus.johansen@ki.au.dk
authors.forename: Claus
authors.initials: C
authors.lastname: Johansen
authors.forename: Jette L
authors.initials: JL
authors.lastname: Riis
authors.forename: Anne
authors.initials: A
authors.lastname: Gedebjerg
authors.forename: Knud
authors.initials: K
authors.lastname: Kragballe
authors.forename: Lars
authors.initials: L
authors.lastname: Iversen
mesh_terms: D000328:Adult; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D006801:Humans; D020381:Interleukin-17 / Q000096:biosynthesis / Q000235:genetics*; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013876:Thiophenes / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D020381:Interleukin-17; D052002:NF-kappa B p50 Subunit; C468119:NF-kappaB decoy; D009838:Oligodeoxyribonucleotides; C477523:SC 514; D013876:Thiophenes; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D004247:DNA