Regulation of nitric-oxide synthase mRNA expression by interferon-gamma and picolinic acid.
Picolinic acid, a catabolite of L-tryptophan, is a potent co-stimulatory agent for the induction of tumoricidal activity and the production of L-arginine-dependent reactive nitrogen intermediates (RNI) in murine macrophages. We studied whether picolinic acid could affect nitric-oxide synthase (NOS) expression at the gene level in the macrophage cell line ANA-1. NOS mRNA was neither constitutively expressed nor induced by treatment with picolinic acid alone. However, low levels of NOS mRNA were induced by interferon (IFN)-gamma alone. In contrast, a major increase of NOS mRNA expression was observed after treatment with IFN-gamma plus picolinic acid. The synergism was already detectable after 5-6 h and increased up to 20 h of treatment. The ability of picolinic acid to augment IFN-gamma-dependent NOS mRNA expression was associated with a parallel increase in transcription, as demonstrated by nuclear run-on experiments. Protein synthesis was required for the induction of NOS mRNA because addition of cycloheximide dramatically reduced IFN-gamma plus picolonic acid-induced NOS mRNA expression. Finally, interleukin-4 significantly decreased IFN-gamma plus picolinic acid-induced NOS mRNA expression and NOS transcription. These data provide evidence of a molecular event connecting arginine and tryptophan metabolic pathways in the generation of RNI, and they indicate that picolinic acid can induce transcriptional activation of gene expression.
Melillo
G
G
Macrophage Cell Biology Section, National Cancer Institute-Frederick Cancer Research and Development Center, National Institutes of Health, Maryland 21702-1201.
Cox
G W
GW
Biragyn
A
A
Sheffler
L A
LA
Varesio
L
L
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis*; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004357:Drug Synergism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007371:Interferon-gamma / Q000494:pharmacology*; D007700:Kinetics; D008264:Macrophages / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D019001:Nitric Oxide Synthase; D010848:Picolinic Acids / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis*; D011994:Recombinant Proteins; D014158:Transcription, Genetic / Q000187:drug effects
D010848:Picolinic Acids; D012333:RNA, Messenger; D011994:Recombinant Proteins; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; C030614:picolinic acid