title: Induction of cyclooxygenase-1 in a human megakaryoblastic cell line (CMK) differentiated by phorbol ester.
abstract: Human megakaryoblastic cells (CMK line) are known to differentiate to mature megakaryocyte-like cells by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). There are two isozymes of prostaglandin-forming cyclooxygenase enzyme. Constitutive cyclooxygenase-1 and inducible cyclooxygenase-2 were followed during differentiation of CMK cells. Treatment of the cells with 0.1 microM TPA for 4 days resulted in a 5-20-fold increase in cyclooxygenase activity. Northern and Western blot analyses revealed that cyclooxygenase-1 mRNA and protein increased in parallel with the enzyme activity. In contrast, cyclooxygenase-2 mRNA was detected only at 3 h. Furthermore, most of the increased cyclooxygenase activity was immunoprecipitated with anti-cyclooxygenase-1 antibody, and was not affected by a cyclooxygenase-2-specific inhibitor, NS-398. These results indicated that cyclooxygenase-1 rather than cyclooxygenase-2 was predominantly induced depending on TPA. The enzyme thus induced was localized by immunoelectron microscopy in nuclear envelope and endoplasmic reticulum of the CMK cells.
authors.affiliation: Department of Biochemistry, Tokushima University, School of Medicine, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ueda
authors.forename: R
authors.initials: R
authors.lastname: Yamashita
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Ishimura
mesh_terms: D016718:Arachidonic Acid / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects*; D051545:Cyclooxygenase 1; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008533:Megakaryocytes / Q000378:metabolism*; D008565:Membrane Proteins; D016253:Microscopy, Immunoelectron; D009578:Nitrobenzenes / Q000494:pharmacology; D011233:Precipitin Tests; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011453:Prostaglandins / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D011453:Prostaglandins; D012333:RNA, Messenger; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D016718:Arachidonic Acid; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D013755:Tetradecanoylphorbol Acetate