Novak U, Cocks B G, Hamilton J A
University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Nucleic Acids Res. 1991 Jun 25;19(12):3389-93. doi: 10.1093/nar/19.12.3389.
Transcription of the human urokinase type plasminogen activator (uPA) gene in HeLa cells is induced by phorbol myristate acetate (PMA), interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha). The response to these factors is rapid, independent of new protein synthesis and amplified in the presence of an inhibitor of protein synthesis, indicating the presence of a labile repressor. A DNA element, similar to the binding site for the transcription factor NFkB, is located around--1865 with respect to the start site of transcription in the uPA promoter and confers superinducibility by these agents in the presence of cycloheximide (CHX). A synthetic copy of this element confers superinducibility on a minimal uPA gene promoter and on the thymidine kinase (TK) gene promoter linked to the chloramphenicol acetyl transferase (CAT) gene. CHX alone does not increase transcription from these constructs in HeLa cells, although it superinduces the effects of PMA, IL-1 and TNF alpha. A second NFkB-like binding site located at around--1835 is not capable of conferring transcriptional activation under the same conditions. Our results suggest that maximal transcriptional activation of the uPA gene by PMA, IL-1 and TNF alpha requires the induction of NFkB activity and the decay of a short lived repressor protein, possibly IkB.
人尿激酶型纤溶酶原激活剂（uPA）基因在HeLa细胞中的转录可被佛波酯肉豆蔻酸酯（PMA）、白细胞介素-1（IL-1）和肿瘤坏死因子α（TNFα）诱导。对这些因子的反应迅速，不依赖于新蛋白质的合成，并且在存在蛋白质合成抑制剂的情况下会被放大，这表明存在一种不稳定的阻遏物。一个与转录因子NFkB结合位点相似的DNA元件，相对于uPA启动子中转录起始位点位于约-1865处，并在存在环己酰亚胺（CHX）的情况下赋予这些因子超诱导性。该元件的合成拷贝在与氯霉素乙酰转移酶（CAT）基因相连的最小uPA基因启动子和胸苷激酶（TK）基因启动子上赋予超诱导性。单独的CHX不会增加HeLa细胞中这些构建体的转录，尽管它能超诱导PMA、IL-1和TNFα的作用。位于约-1835处的第二个NFkB样结合位点在相同条件下不能赋予转录激活作用。我们的结果表明，PMA、IL-1和TNFα对uPA基因的最大转录激活需要诱导NFkB活性以及一种可能是IkB的短寿命阻遏蛋白的降解。
