Lobo F M, Xu S, Lee C, Fuleihan R L
Yale Child Health Research Center, Yale University School of Medicine, New Haven, Connecticut, USA.
Biochem Biophys Res Commun. 2000 Dec 9;279(1):245-50. doi: 10.1006/bbrc.2000.3914.
CD40 ligand (CD40L, CD154) is a T cell cytokine with highly regulated expression that requires the transcription factor nuclear factor of activated T cells (NF-AT) to bind at two sites in the proximal CD40L promoter. We have determined that the distal CD40L promoter (-500 to -1300 bp from start of transcription) conveys superior promoter activity in reporter gene assays. Within the distal promoter, we have identified a third NF-AT binding site, at -761 to -756. Oligonucleotides incorporating each of the three NF-AT sites cross-compete for binding of nuclear extracts from activated T cells and bind NF-ATc2 by antibody supershift. Mutation of the distal NF-AT site reduces activity of the 1300 bp CD40L promoter construct to that of the proximal 500 bp construct, which includes only two NF-AT sites. This suggests that the newly identified NF-AT site is the major mediator of transcriptional activation in the distal CD40L promoter.
CD40配体（CD40L，CD154）是一种表达受到高度调控的T细胞细胞因子，它需要活化T细胞核因子（NF-AT）转录因子结合在近端CD40L启动子的两个位点上。我们已经确定，远端CD40L启动子（转录起始点上游-500至-1300 bp）在报告基因检测中表现出更强的启动子活性。在远端启动子内，我们在-761至-756处鉴定出第三个NF-AT结合位点。包含这三个NF-AT位点的寡核苷酸相互竞争结合活化T细胞核提取物，并通过抗体超迁移结合NF-ATc2。远端NF-AT位点的突变使1300 bp CD40L启动子构建体的活性降低至近端500 bp构建体的活性水平，近端构建体仅包含两个NF-AT位点。这表明新鉴定出的NF-AT位点是远端CD40L启动子转录激活的主要介导因子。
