Differential regulation of the IL-12 p40 promoter and of p40 secretion by CpG DNA and lipopolysaccharide.
Challenge of macrophages with DNA containing an internal CpG motif results in IL-12 p40 secretion. In the presence of IFN-gamma, CpG DNA induces more p40 secretion than does LPS. In the RAW 264 macrophage cell line, both CpG DNA and LPS activate a p40 promoter-reporter construct, and the promoter response to either agent is augmented 2- to 5-fold by IFN-gamma. While either LPS or CpG DNA induces p40 promoter activity, only CpG DNA induces an increase in p40 mRNA or protein secretion. Even though IFN-gamma augmented LPS-driven p40 promoter activity in RAW 264 cells, the combination of IFN-gamma and LPS induced less p40 mRNA or protein secretion than the combination of IFN-gamma and CpG DNA. The ability of IFN-gamma to augment LPS or CpG DNA-induced p40 promoter activation was observed with truncation mutants of the IL-12 promoter containing as few as 250 bp 5' of the TATA box. Although LPS alone is a poor inducer of p40 transcription, both LPS and CpG DNA induce similar nuclear translocation of NF-kappaB. This binding is not augmented by costimulation with IFN-gamma. Thus, CpG DNA induces p40 transcription by a mechanism that includes NF-kappaB translocation; however, CpG DNA appears to induce other factor(s) necessary for p40 transcription. These results illustrate fundamental differences between CpG DNA and LPS with respect to activation of IL-12 p40 secretion.
Cowdery
J S
JS
Department of Veterans Affairs Medical Center, Iowa City 52246, USA. john-cowdery@uiowa.edu
Boerth
N J
NJ
Norian
L A
LA
Myung
P S
PS
Koretzky
G A
GA
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D018899:CpG Islands / Q000276:immunology*; D004247:DNA / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000276:immunology*; D007371:Interferon-gamma / Q000494:pharmacology; D018664:Interleukin-12 / Q000235:genetics* / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D009841:Oligonucleotides / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000276:immunology*; D020218:Response Elements / Q000276:immunology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D000276:Adjuvants, Immunologic; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009841:Oligonucleotides; D014157:Transcription Factors; D018664:Interleukin-12; D007371:Interferon-gamma; D004247:DNA