Interferon regulatory factor 3 is involved in Toll-like receptor 4 (TLR4)- and TLR3-induced IL-12p35 gene activation.
Interleukin-12 (IL-12) is a heterodimeric cytokine produced by dendritic cells (DCs) in response to Toll-like receptor (TLR) ligation. While the mechanisms regulating IL-12p40 chain gene expression are well characterized, molecular events involved in IL-12p35 chain gene activation remain to be clarified. Since IL-12p35 mRNA was induced in human DCs activated through TLR3 or TLR4 but not TLR2, we investigated the potential role of interferon regulatory factor 3 (IRF-3) in IL-12p35 gene transactivation. First, a binding site for IRF-3 named interferon-stimulated response element-1 (ISRE-1) was identified in the human IL-12p35 promoter region between nucleotides -251 and -240. The ISRE-1 site was required for IL-12p35 gene activation in RAW 264.7 cells stimulated by lipopolysaccharide (LPS) or PolyI:C. Ectopic expression of IRF-3 was found to up-regulate IL-12p35 gene activation in the same system. Furthermore, chromatin immunoprecipitation (ChIP) studies demonstrated that IRF-3 is recruited to ISRE-1 site in TLR4- or TLR3-stimulated human DCs. Finally, experiments on DCs from IRF-3-deficient mice established that TLR4-induced IL-12p35 mRNA and IL-12p70 synthesis are impaired in absence of IRF-3. We conclude that IRF-3 binds to a critical cis-acting element in the IL-12p35 gene promoter and thereby represents a key factor for the induction of IL-12p70 synthesis in DCs.
Goriely
Stanislas
S
Institute for Medical Immunology (IMI), Université Libre de Bruxelles, Charleroi, Belgium.
Molle
Céline
C
Nguyen
Muriel
M
Albarani
Valentina
V
Haddou
Najate Ouled
NO
Lin
Rongtuan
R
De Wit
Dominique
D
Flamand
Véronique
V
Willems
Fabienne
F
Goldman
Michel
M
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000172:deficiency / Q000276:immunology*; D018664:Interleukin-12 / Q000235:genetics / Q000276:immunology*; D053765:Interleukin-12 Subunit p35; D053762:Interleukin-12 Subunit p40; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D011070:Poly I-C / Q000494:pharmacology; D021122:Protein Subunits / Q000235:genetics / Q000276:immunology*; D020218:Response Elements / Q000235:genetics / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology*; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology*
D000998:Antiviral Agents; C508858:IL12A protein, human; C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D053765:Interleukin-12 Subunit p35; D053762:Interleukin-12 Subunit p40; C494233:Irf3 protein, mouse; D008070:Lipopolysaccharides; D021122:Protein Subunits; C495344:TLR3 protein, human; C495345:TLR4 protein, human; C493487:Tlr4 protein, mouse; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D018664:Interleukin-12; D011070:Poly I-C