Wu J, Grindlay G J, Johnson C, Allan M
Department of Genetics, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
Proc Natl Acad Sci U S A. 1990 Oct;87(20):8115-9. doi: 10.1073/pnas.87.20.8115.
We have used a competition assay to investigate the influence of erythroid-specific cellular factors on transcription from the human epsilon-globin major cap site promoter and the minor promoter located 200 base pairs (bp) upstream from the epsilon-globin cap site. In the human erythroid cell line K562, competition of the epsilon-globin major cap site promoter linked to the chloramphenicol acetyltransferase (CAT) gene (epsilon P-CAT) with the same promoter fragment linked to a neomycin resistance gene (epsilon P-NEO) leads to a reduction in CAT activity. This indicates the specific presence of K562 cells of factor(s) which interact with the 200-bp promoter fragment (isolated from the gene body or flanking sequences) to activate transcription from the epsilon-globin major cap site. Competition of the epsilon-globin major promoter (as epsilon P-CAT) with the upstream minor epsilon-globin promoter (as epsilon P2-NEO) also leads to a reduction in CAT activity, indicating that both promoters share erythroid-specific trans-acting factors. The reverse competition (epsilon P2-CAT with epsilon P-NEO) leads to an increase in CAT activity, suggesting that the existence of erythroid-specific factor(s) which repress transcription from the 200-bp-upstream epsilon-globin promoter.
我们使用了一种竞争分析方法来研究红系特异性细胞因子对人ε-珠蛋白主要帽位点启动子以及位于ε-珠蛋白帽位点上游200个碱基对（bp）处的次要启动子转录的影响。在人红系细胞系K562中，与氯霉素乙酰转移酶（CAT）基因相连的ε-珠蛋白主要帽位点启动子（εP-CAT）与与新霉素抗性基因相连的相同启动子片段（εP-NEO）竞争，导致CAT活性降低。这表明K562细胞中存在与200-bp启动子片段（从基因体或侧翼序列分离）相互作用以激活ε-珠蛋白主要帽位点转录的因子。ε-珠蛋白主要启动子（作为εP-CAT）与上游的ε-珠蛋白次要启动子（作为εP2-NEO）竞争也导致CAT活性降低，表明两个启动子共享红系特异性反式作用因子。反向竞争（εP2-CAT与εP-NEO）导致CAT活性增加，提示存在抑制200-bp上游ε-珠蛋白启动子转录的红系特异性因子。
