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Induction of cyclooxygenase-1 in a human megakaryoblastic cell line (CMK) differentiated by phorbol ester

Authors
  • Ueda, Natsuo
  • Yamashita, Rieko
  • Yamamoto, Shozo
  • Ishimura, Kazunori
Type
Published Article
Journal
Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism
Publisher
Elsevier
Publication Date
Jan 01, 1997
Accepted Date
Sep 04, 1996
Volume
1344
Issue
1
Pages
103–110
Identifiers
DOI: 10.1016/S0005-2760(96)00131-2
Source
Elsevier
Keywords
License
Unknown

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 μM 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.

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