Chen L C, Chen B K, Liu Y W, Chang W C
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
FEBS Lett. 1999 Jul 16;455(1-2):105-10. doi: 10.1016/s0014-5793(99)00865-0.
Transforming growth factor-alpha (TGF-alpha) increased the expression of 12-lipoxygenase activity in a time-dependent manner in human epidermoid carcinoma A431 cells. The increase of 12-lipoxygenase activity was accompanied by an increase in 12-lipoxygenase mRNA. The effect of TGF-alpha on the promoter activation of 12-lipoxygenase gene was analyzed by using the luciferase fusion vectors. A dose-dependent effect of TGF-alpha on the reporter activity was observed, which paralleled with its effect on enzyme activity. Transient transfection with a series of 5'-deleted constructs showed that the 5'-flanking region spanning from -224 to -100 bp from translation starting site played an important role for TGF-alpha response. Site-directed mutagenesis and gel mobility shift assay indicated that two Sp1 binding sequences residing at -158 to -150 bp and 123 to -114 bp were responsible for the TGF-alpha in activation of human 12-lipoxygenase gene transcription. Expression of Sp1, but not Sp3, stimulated the promoter activity of 12-lipoxygenase in SL2 cells, indicating that the binding of Sp1 with Sp1 binding sequences played a significant role in the regulation of 12-lipoxygenase gene.
转化生长因子-α（TGF-α）可使人类表皮样癌A431细胞中的12-脂氧合酶活性表达呈时间依赖性增加。12-脂氧合酶活性的增加伴随着12-脂氧合酶mRNA的增加。利用荧光素酶融合载体分析了TGF-α对12-脂氧合酶基因启动子激活的作用。观察到TGF-α对报告基因活性有剂量依赖性作用，这与其对酶活性的作用平行。用一系列5'端缺失构建体进行瞬时转染表明，从翻译起始位点起跨度为-224至-100 bp的5'侧翼区域对TGF-α反应起重要作用。定点诱变和凝胶迁移率变动分析表明，位于-158至-150 bp和-123至-114 bp的两个Sp1结合序列负责TGF-α对人类12-脂氧合酶基因转录的激活。Sp1而非Sp3的表达刺激了SL2细胞中12-脂氧合酶的启动子活性，表明Sp1与Sp1结合序列的结合在12-脂氧合酶基因的调控中起重要作用。
