Octamer binding protein-1 is involved in inhibition of inducible nitric oxide synthase expression by exogenous nitric oxide in murine liver cells.
Nitric oxide (NO) has diverse effects on immune responses and hepatic functions. In BNL CL.2 cells, the murine embryonic liver cells, inducible nitric oxide synthase (iNOS) mRNA expression appeared after 3 h of treatment with IFN-gamma and LPS. Interestingly, mRNA and protein expression of iNOS was down-regulated by sodium nitroprusside (SNP) and diethylamine dinitric oxide in a time- and dose-dependent manner, but not by H2O2. TNF-alpha gene expression was also dramatically reduced by SNP, but IL-6 gene expression was inhibited much less. IFN-gamma and LPS-induced chloramphenicol acetyltransferase activity of iNOS promoter constructs was inhibited by SNP. Electrophoretic mobility shift assay showed that SNP inhibited IFN-gamma plus LPS-induced Oct-1 binding activity, and the inhibition was reversed by DTT. Mutation in the Oct-1 site completely abolished iNOS promoter activity. In addition, supershift assay and Southwestern analysis demonstrated that the Oct-1 binding activity was inhibited by SNP. Taken together, these results indicate that NO suppresses IFN-gamma plus LPS-induced iNOS expression, and that Oct-1 is an important element in this process.
Lee
B S
BS
Laboratory of Immunology, Korea Research Institute of Bioscience and Biotechnology, Yusong, Taejon 305-333, Korea.
Kim
Y M
YM
Kang
H S
HS
Kim
H M
HM
Pyun
K H
KH
Choi
I
I
D000818:Animals; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian / Q000166:cytology; D051863:Host Cell Factor C1; D007202:Indicators and Reagents / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects; D051379:Mice; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D009599:Nitroprusside / Q000494:pharmacology; D050811:Octamer Transcription Factor-1; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D013997:Time Factors; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects*
D004268:DNA-Binding Proteins; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D007202:Indicators and Reagents; D008070:Lipopolysaccharides; D050811:Octamer Transcription Factor-1; C494166:Pou2f1 protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D009599:Nitroprusside; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse