Stricker K, Serfling E, Krammer P H, Falk W
Institute for Immunology and Genetics, German Cancer Research Center, Heidelberg, FRG.
Eur J Immunol. 1993 Jul;23(7):1475-80. doi: 10.1002/eji.1830230712.
Interleukin-1 (IL-1) costimulation is required for efficient IL-2 synthesis and IL-2 receptor (IL-2R) expression of T cells. The molecular events leading to these effects are largely unknown. We utilized an IL-1-responsive and an IL-1-non-responsive subclone of the mouse thymoma cell line EL4 to investigate how IL-1 activates IL-2 gene expression. We correlated IL-2 promoter activity with the activity of the endogenous IL-2 gene, thereby showing the biological significance of our results. Our experiments provide new functional data showing that a major target of IL-1 mediated costimulation is the chi B-like site, T cell element distal TCEd (GGGATTTCAC), of the IL-2 promoter. Thus, deletion or mutation of TCEd within a complete IL-2 promoter abrogated IL-1 costimulation in the IL-1 responsive EL4 subclone. Therefore, the TCEd element is functionally essential for the effect of IL-1. We also identified a nuclear factor (NF), IL-1 NF, that binds to the TCEd site after IL-1 stimulation. This factor was only present in the IL-1-responsive EL4 subclone and not in the IL-1-non-responsive subclone after IL-1 stimulation and did not appear after phytohemagglutinin (PHA)-treatment. Binding of IL-1 NF to the TCEd site was competed by a typical chi B oligonucleotide, suggesting that it is similar to NF-chi B in its DNA-binding properties. However, the TCEd element was only activated by costimulation with PHA and IL-1 whereas a typical chi B element was already activated by IL-1 alone. These data suggest that the biological function of the TCEd element of the IL-2 promoter differs from that of a canonical chi B element. Our data provide new evidence that IL-1 acts on the IL-2 promoter by activating the TCEd element via the transcription factor IL-1 NF. Furthermore, activation of this element requires two signals, delivered by IL-1 and PHA, in this way reflecting the activation requirement for the endogenous IL-2 gene.
白细胞介素-1（IL-1）共刺激是T细胞高效合成IL-2及表达IL-2受体（IL-2R）所必需的。导致这些效应的分子事件在很大程度上尚不清楚。我们利用小鼠胸腺瘤细胞系EL4的一个IL-1反应性亚克隆和一个IL-1无反应性亚克隆来研究IL-1如何激活IL-2基因表达。我们将IL-2启动子活性与内源性IL-2基因的活性相关联，从而证明了我们结果的生物学意义。我们的实验提供了新的功能数据，表明IL-1介导的共刺激的一个主要靶点是IL-2启动子的chi B样位点，即远端T细胞元件TCEd（GGGATTTCAC）。因此，在完整的IL-2启动子内删除或突变TCEd可消除IL-1反应性EL4亚克隆中的IL-1共刺激。所以，TCEd元件对于IL-1的效应在功能上是必不可少的。我们还鉴定出一种核因子（NF），即IL-1 NF，它在IL-1刺激后与TCEd位点结合。该因子仅在IL-1刺激后的IL-1反应性EL4亚克隆中存在，在IL-1无反应性亚克隆中不存在，且在植物血凝素（PHA）处理后不出现。IL-1 NF与TCEd位点的结合可被典型的chi B寡核苷酸竞争，这表明其在DNA结合特性上与NF-chi B相似。然而，TCEd元件仅在与PHA和IL-1共刺激时被激活，而典型的chi B元件仅被IL-1单独激活。这些数据表明IL-2启动子的TCEd元件的生物学功能与典型的chi B元件不同。我们的数据提供了新的证据，即IL-1通过转录因子IL-1 NF激活TCEd元件作用于IL-2启动子。此外，该元件的激活需要由IL-1和PHA传递的两个信号，以此反映内源性IL-2基因的激活需求。
