IFN-gamma + LPS induction of iNOS is modulated by ERK, JNK/SAPK, and p38(mapk) in a mouse macrophage cell line.
Nitric oxide (NO.) produced by inducible nitric oxide synthase (iNOS) mediates a number of important physiological and pathophysiological processes. The objective of this investigation was to examine the role of mitogen-activated protein kinases (MAPKs) in the regulation of iNOS and NO. by interferon-gamma (IFN-gamma) + lipopolysaccharide (LPS) in macrophages using specific inhibitors and dominant inhibitory mutant proteins of the MAPK pathways. The signaling pathway utilized by IFN-gamma in iNOS induction is well elucidated. To study signaling pathways that are restricted to the LPS-signaling arm, we used a subclone of the parental RAW 264.7 cell line that is unresponsive to IFN-gamma alone with respect to iNOS induction. In this RAW 264.7gammaNO(-) subclone, IFN-gamma and LPS are nevertheless required for synergistic activation of the iNOS promoter. We found that extracellular signal-regulated kinase (ERK) augmented and p38(mapk) inhibited IFN-gamma + LPS induction of iNOS. Dominant-negative MAPK kinase-4 inhibited iNOS promoter activation by IFN-gamma + LPS, also implicating the c-Jun NH(2)-terminal kinase (JNK) pathway in mediating iNOS induction. Inhibition of the ERK pathway markedly reduced IFN-gamma + LPS-induced tumor necrosis factor-alpha protein expression, providing a possible mechanism by which ERK augments iNOS expression. The inhibitory effect of p38(mapk) appears more complex and may be due to the ability of p38(mapk) to inhibit LPS-induced JNK activation. These results indicate that the MAPKs are important regulators of iNOS-NO. expression by IFN-gamma + LPS.
Chan
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Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80206, USA. chane@njc.org
Riches
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DW
D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins; D004357:Drug Synergism; D004790:Enzyme Induction / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D007093:Imidazoles / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000502:physiology; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000494:pharmacology*; D048369:MAP Kinase Kinase 1; D048670:MAP Kinase Kinase 4; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007375:Interleukin-1; D008070:Lipopolysaccharides; D009573:Nitrites; D009687:Nuclear Proteins; C095938:Pa2g4 protein, mouse; D011725:Pyridines; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048670:MAP Kinase Kinase 4; C482127:Map2k1 protein, mouse; C482562:Map2k4 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; C093642:SB 203580