Mahmud I, Suzuki T, Yamamoto Y, Suzuki H, Takahashi Y, Yoshimoto T, Yamamoto S
Department of Biochemistry, Tokushima University School of Medicine, Japan.
Biochim Biophys Acta. 1993 Feb 24;1166(2-3):211-6. doi: 10.1016/0005-2760(93)90099-u.
When human erythroleukemia (HEL) cells were incubated with arachidonic acid, both fatty acid cyclooxygenase and arachidonate 12-lipoxygenase activities were exhibited. Subcellular localization of these enzymes were examined by differential centrifugation, and both the cyclooxygenase and the 12-lipoxygenase were present predominantly in the microsomes rather than the cytosol of the cells. The cyclooxygenase activity was stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) in a dose-dependent and time-dependent manner. Actual increase in the cyclooxygenase protein by TPA was demonstrated by immunoprecipitation and Western blot analysis of the enzyme with the aid of an anti-cyclooxygenase antibody. Furthermore, the cyclooxygenase mRNA level increased as assessed by RNA blot analysis using a cDNA probe for the enzyme. In contrast, the TPA treatment reduced the activity of 12-lipoxygenase. By RNA blot analysis using a cDNA probe of HEL cell 12-lipoxygenase, the mRNA level of the enzyme was shown to decline by the TPA treatment. Taken together, the TPA treatment of HEL cells brought about the induction of cyclooxygenase and the suppression of 12-lipoxygenase.
当人红白血病（HEL）细胞与花生四烯酸一起孵育时，脂肪酸环氧化酶和花生四烯酸12 -脂氧合酶的活性均表现出来。通过差速离心法检测这些酶的亚细胞定位，环氧化酶和12 -脂氧合酶主要存在于微粒体中，而非细胞的胞质溶胶中。环氧化酶活性受到12 - O -十四酰佛波醇13 -乙酸酯（TPA）以剂量和时间依赖性方式的刺激。借助抗环氧化酶抗体，通过对该酶进行免疫沉淀和蛋白质印迹分析，证实TPA使环氧化酶蛋白实际增加。此外，使用该酶的cDNA探针通过RNA印迹分析评估，环氧化酶mRNA水平升高。相反，TPA处理降低了12 -脂氧合酶的活性。使用HEL细胞12 -脂氧合酶的cDNA探针进行RNA印迹分析表明，TPA处理使该酶的mRNA水平下降。综上所述，TPA处理HEL细胞导致环氧化酶的诱导和12 -脂氧合酶的抑制。
