title: Protein kinase C-θ promotes Th17 differentiation via upregulation of Stat3.
abstract: Although protein kinase C-θ (PKC-θ)-deficient mice are resistant to the induction of Th17-dependent experimental autoimmune encephalomyelitis, the function of PKC-θ in Th17 differentiation remains unknown. In this article, we show that purified, naive CD4 PKC-θ(-/-) T cells were defective in Th17 differentiation, whereas Th1 and Th2 differentiation appeared normal. Activation of PKC-θ with PMA promoted Th17 differentiation in wild type (WT) but not PKC-θ(-/-) T cells. Furthermore, PKC-θ(-/-) T cells had notably lower levels of Stat3, a transcription factor required for Th17 differentiation, and PMA markedly stimulated the expression of Stat3 in WT but not PKC-θ(-/-) T cells. In contrast, activation of Stat4 and Stat6, which are critical for Th1 and Th2 differentiation, was normal in PKC-θ(-/-) T cells. Forced expression of Stat3 significantly increased Th17 differentiation in PKC-θ(-/-) T cells, suggesting that reduced Stat3 levels were responsible for impaired Th17 differentiation, and that Stat3 lies downstream of PKC-θ. Constitutively active PKC-θ, or WT PKC-θ activated by either PMA or TCR cross-linking, stimulated expression of a luciferase reporter gene driven by the Stat3 promoter. PKC-θ-mediated activation of the Stat3 promoter was inhibited by dominant-negative AP-1 and IκB kinase-β, but stimulated by WT AP-1 and IκB kinase-β, suggesting that PKC-θ stimulates Stat3 transcription via the AP-1 and NF-κB pathways. Lastly, conditions favoring Th17 differentiation induced the highest activation level of PKC-θ. Altogether, the data indicate that PKC-θ integrates the signals from TCR signaling and Th17 priming cytokines to upregulate Stat3 via NF-κB and AP-1, resulting in the stimulation of Th17 differentiation.
authors.affiliation: Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
authors.forename: Myung-Ja
authors.initials: MJ
authors.lastname: Kwon
authors.forename: Jian
authors.initials: J
authors.lastname: Ma
authors.forename: Yan
authors.initials: Y
authors.lastname: Ding
authors.forename: Ruiqing
authors.initials: R
authors.lastname: Wang
authors.forename: Zuoming
authors.initials: Z
authors.lastname: Sun
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000276:immunology*; D047369:Chromatin Immunoprecipitation; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology; D047468:Immunoprecipitation; D007527:Isoenzymes / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D058504:Th17 Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D007527:Isoenzymes; D050796:STAT3 Transcription Factor; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta