Induction of cyclooxygenase-2 in macrophages by catalase: role of NF-κB and PI3K signaling pathways
Section snippets
Materials and methods
Materials. Catalase (C-40), aprotinin, leupeptin, and 3-amino-1,2,4-triazole (AT) were purchased from Sigma. Antibodies against anti-rabbit or mouse secondary horseradish peroxidase and ECL Western detection reagents were purchased from Amersham Biosciences. PD98059 (an ERK inhibitor), SB203580 (a p38 inhibitor), LY294002 (a PI3K inhibitor), SP600125 (a JNK inhibitor), Z-Leu-Leu-Leu-H (MG132, a proteosomal and NF-κB inhibitor), rapamycin (an inhibitor of mammalian target of rapamycin/S6 kinase
Induction of COX-2 in Raw 264.7 macrophages by catalase
We initially investigated the effect of different concentrations of catalase on COX-2 protein and mRNA expression in Raw cells. As shown in Fig. 1A, the addition of catalase into Raw cells for 6 h induced a dose-dependent increase of COX-2 protein and mRNA. There were already substantial amounts of COX-2 protein and mRNA expression by treatment with catalase at 100 U/ml. Expression levels of COX-2 protein and mRNA were further elevated as treatment doses of catalase were increased. Data of
Discussion
In this study, we have demonstrated that catalase induces the expression of COX-2 in Raw 264.7 macrophages. Furthermore, we have shown that the COX-2 induction by catalase in Raw cells requires its enzymatic activity, based on the fact that catalase, which lost its activity by AT, a catalase activity inhibitor before addition to cells, concomitantly lost its COX-2 inducing ability. Mechanistic analyses have further shown that the catalase-induced COX-2 expression in Raw cells is correlated with
Acknowledgements
We deeply thank Dr. H. Herschman (UCLA, CA) for providing us a luciferase DNA construct containing a murine COX-2 promoter. This work was supported by the Korea Science and Engineering Foundation (KOSEF) through the Chronic Disease Research Center at Keimyung University.
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