Superinduction of cyclooxygenase-2 by NO(*) and agonist challenge involves transcriptional regulation mediated by AP-1 activation.
Superinduction of cyclooxygenase-2, in murine RAW 264.7 macrophages as well as human pulmonary type II A549 epithelial cells, is achieved by the simultaneous addition of agonists such as lipopolysaccharide or interleukin-1beta and the NO(*) donor S-nitrosoglutathione. NO(*)-evoked superinduction of cyclooxygenase-2 in the presence of agonists was dose-dependent and required transcriptional as well as translational regulation. We sought to further analyze NO(*)-elicited superinduction at the level of the transcription factor NF-kappaB that is obligatory for cyclooxygenase-2 expression. NO(*)-mediated NF-kappaB activation was restricted to low concentrations of S-nitrosoglutathione (50-200 microM), while a higher dose of S-nitrosoglutathione (1 mM) was ineffective. Not observing a correlation between NF-kappaB activation and cyclooxygenase-2 expression under NO(*)-delivery stimulated our interest in analyzing AP-1. NO(*) efficiently activated AP-1 at all concentrations tested. The involvement of AP-1 in promoting cyclooxygenase-2 superinduction was established in cells transfected with the dominant-negative c-Jun mutant, TAM-67. Enhanced expression of cyclooxygenase-2 by lipopolysaccharide/S-nitrosoglutathione-treatment was attenuated in TAM-67 transfectants, while the response to lipopolysaccharide alone remained unaffected. We conclude that AP-1 activation exclusively conveys the NO(*) signal that is required for superinduction of cyclooxygenase-2. Superinduction of cyclooxygenase-2 is restricted to a situation where both, NF-kappaB and AP-1 are activated. Under inflammatory conditions this might be achieved by the costimulatory signals provided by agonist challenge and NO(*).
von Knethen
A
A
University of Erlangen-Nürnberg, Faculty of Medicine, Department of Medicine IV-Experimental Division, Loschgestrasse 8, 91054 Erlangen, Germany.
Brüne
B
B
D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2; D004790:Enzyme Induction / Q000235:genetics; D004847:Epithelial Cells / Q000201:enzymology; D005609:Free Radicals / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D008264:Macrophages / Q000201:enzymology / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D009569:Nitric Oxide / Q000819:agonists / Q000502:physiology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D018808:Transcription Factor AP-1 / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection
D005609:Free Radicals; D007527:Isoenzymes; D008565:Membrane Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D009569:Nitric Oxide; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases