IL-12 and IL-18 differentially regulate the transcriptional activity of the human IFN-gamma promoter in primary CD4+ T lymphocytes.
We analyzed the molecular mechanisms by which IL-12 and IL-18 induce transcriptional activity of the IFN-gamma promoter in primary human CD4+ T cells. In transfection experiments, we found that IL-18 directly induces IFN-gamma promoter activity, whereas significant activation with IL-12 required costimulation with alphaCD3/CD28. Furthermore, IL-12 caused in vivo protection of a STAT4 (-236) binding site, whereas stimulation with IL-18 or IL-12 plus alphaCD3/CD28 induced occupancy of a downstream AP-1 site. Mutation of this AP-1 site abrogated both IL-12- and IL-18-mediated promoter activation, whereas mutation of the STAT site inhibited IL-12-dependent activation. These data suggest that both AP-1 and STAT4 are required for IL-12-dependent IFN-gamma promoter activity, whereas IL-18 causes direct activation via AP-1. This differential activation of the IFN-gamma promoter gives further insights into molecular pathways governing Th1 T cell development and differentiation.
Barbulescu
K
K
Laboratory of Immunology, I. Medical Clinic, University of Mainz, Germany.
Becker
C
C
Schlaak
J F
JF
Schmitt
E
E
Meyer zum Büschenfelde
K H
KH
Neurath
M F
MF
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D018983:DNA Footprinting; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics*; D018664:Interleukin-12 / Q000494:pharmacology*; D020382:Interleukin-18; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D050797:STAT4 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
D016207:Cytokines; D017931:DNA Primers; D004268:DNA-Binding Proteins; D020382:Interleukin-18; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D018664:Interleukin-12; D007371:Interferon-gamma