Suppression of NF-kappaB and IRF-1-induced transcription of the murine IL-12 p40 by transforming growth factor-beta Smad pathway in macrophages.
In this study, we have characterized the negative regulation of the IL-12 p40 expression by TGF-beta in macrophages. Although murine IL-12 p40 promoter contains a putative TGF-beta inhibitory element (TIE), neither mutation nor deletion of the TIE had any effect on the inhibitory activity of TGF-beta. The NF-kappaB p65 and interferon regulatory factor (IRF)-1 induced promoter activity was suppressed by the expression of a constitutively active TGF-beta type I receptor in the presence of Smad3 and Smad4, which was abrogated by expression of an inhibitory Smad, Smad7. Transcription of a reporter gene containing three copies of both NF-kappaB and IRF-1 elements from the IL-12 p40 promoter was significantly repressed by activation of Smad-dependent TGF-beta pathway. In contrast, reporter containing three copies of either the NF-kappaB or IRF-1 sites was not affected by TGF-beta-Smad pathway. These findings indicated that both the NF-kappaB and IRF-1 sites are required for the repression of promoter activity of IL-12 p40 by TGF-beta.
Ogawa
Kenji
K
Laboratory of Cellular Biochemistry, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. kkogawa@riken.jp
Funaba
Masayuki
M
Tsujimoto
Masafumi
M
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology; D053762:Interleukin-12 Subunit p40 / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D050856:Interferon Regulatory Factor-1; D053762:Interleukin-12 Subunit p40; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D007371:Interferon-gamma