Suppression of Il-12 transcription in macrophages following Fc gamma receptor ligation

• Published in: The Journal of immunology (1950) 2001-04, Vol.166 (7), p.4498-4506
• Main Authors: Grazia Cappiello, M, Sutterwala, F S, Trinchieri, G, Mosser, D M, Ma, X
• Format: Article
• Language: English
• Subjects: Active Transport, Cell Nucleus - immunology; AFc receptors; Animals; Binding, Competitive - genetics; Binding, Competitive - immunology; Cell Line; Cell Nucleus - immunology; Cell Nucleus - metabolism; DNA-Binding Proteins - antagonists & inhibitors; DNA-Binding Proteins - metabolism; Down-Regulation - genetics; Down-Regulation - immunology; Gene Expression Regulation - immunology; Genetic Vectors - pharmacology; Interferon Regulatory Factor-1; Interferon Regulatory Factors; Interferon-gamma - metabolism; Interleukin-12 - antagonists & inhibitors; Interleukin-12 - biosynthesis; Interleukin-12 - genetics; Interleukin-12 - metabolism; Ligands; Macromolecular Substances; Macrophages - immunology; Macrophages - metabolism; Mice; Phosphoproteins - antagonists & inhibitors; Phosphoproteins - metabolism; Promoter Regions, Genetic - immunology; Protein Binding - genetics; Protein Binding - immunology; Protein Structure, Tertiary - genetics; Proto-Oncogene Proteins - antagonists & inhibitors; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins - physiology; PU.1 protein; Receptors, IgG - immunology; Receptors, IgG - metabolism; Repressor Proteins - antagonists & inhibitors; Repressor Proteins - metabolism; Trans-Activators - antagonists & inhibitors; Trans-Activators - genetics; Trans-Activators - metabolism; Trans-Activators - physiology; Transcription Factors; Transcription, Genetic - immunology; Transfection
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.166.7.4498

Ligating Fc gamma R on macrophages results in suppression of IL-12 production. We show that Fc gamma R ligation selectively down-regulates IL-12 p40 and p35 gene expression at the level of transcription. The region responsive to this inhibition maps to the Ets site of the p40 promoter. PU.1, IFN consensus sequence binding protein, and c-REL: form a complex on this element upon macrophage activation. Receptor ligation abolishes the binding of this PU.1-containing activation complex, and abrogates p40 transcription. A dominant-negative construct of PU.1 diminishes IL-12 p40 promoter activity and endogenous IL-12 p40 protein secretion. Thus, the specificity of IL-12 down-regulation following receptor ligation lies in the inhibition of binding of a PU.1-containing complex to the Ets site of the IL-12 promoter. These findings provide evidence demonstrating for the first time the importance of PU.1 in the transcriptional regulation of IL-12 gene expression.