Expression of mitogen-inducible cyclooxygenase induced by lipopolysaccharide: mediation through both mitogen-activated protein kinase and NF-kappaB signaling pathways in macrophages.
The mitogen-inducible cyclooxygenase (COX-2) is selectively expressed in lipopolysaccharide (LPS)-stimulated macrophages. However, the signaling pathways that lead to the expression of COX-2 in LPS-stimulated macrophages are not well understood. LPS activates members of mitogen-activated protein kinases (MAPKs) and NF-kappaB transcription factor in macrophages. We have shown that protein tyrosine kinase (PTK) inhibitors suppress the LPS-induced expression of COX-2 in macrophages (Chanmugam et al., J Biol Chem 270: 5418-5426, 1995). These PTK inhibitors also inhibit LPS-induced activation of MAPKs. Thus, in the present study, we determined whether the activation of MAPKs and NF-kappaB is necessary for the signaling pathway for the LPS-induced expression of COX-2 in the murine macrophage cell line RAW 264.7. The findings demonstrated that inhibition of extracellular signal-regulated protein kinases 1 and 2 (ERK-1 and -2) by the selective inhibitor PD98059 or inhibition of P38 by the specific inhibitor SB203580 results in partial suppression of COX-2 expression. However, activation of MAPKs by phorbol 12-myristate 13-acetate, H2O2, sorbitol, sodium vanadate, or a combination of these agents failed to induce the expression of COX-2. Inhibitors of NF-kappaB suppressed COX-2 expression without affecting tyrosine phosphorylation of MAPKs. The PTK inhibitors that suppressed the activation of MAPKs and COX-2 expression also inhibited the degradation of IkappaB-alpha. Together, these results indicate that the activation of NF-kappaB is required to induce the expression of COX-2 in LPS-stimulated RAW 264.7 cells. Inhibition of ERK-1 and 2 or P38 results in partial suppression of COX-2 expression. However, the activation of MAPKs alone is not sufficient to induce the expression of COX-2 in these cells.
Hwang
D
D
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808, U.S.A. hwangdh@mhs.pbrc.edu
Jang
B C
BC
Yu
G
G
Boudreau
M
M
D000818:Animals; D016227:Benzoquinones; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000032:analysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D020672:I-kappa B Proteins; D007093:Imidazoles / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D007783:Lactones / Q000494:pharmacology; D008070:Lipopolysaccharides; D018942:Macrolides; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction
D016227:Benzoquinones; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D020672:I-kappa B Proteins; D007093:Imidazoles; D047029:Lactams, Macrocyclic; D007783:Lactones; D008070:Lipopolysaccharides; D018942:Macrolides; D008934:Mitogens; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D011725:Pyridines; D011809:Quinones; D012333:RNA, Messenger; D000072000:NF-KappaB Inhibitor alpha; D017828:Rifabutin; C020754:herbimycin; D011451:Prostaglandin-Endoperoxide Synthases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C035359:monorden; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one