de Martin R, Vanhove B, Cheng Q, Hofer E, Csizmadia V, Winkler H, Bach F H
Vienna International Research Cooperation Center (VIRCC), Austria.
EMBO J. 1993 Jul;12(7):2773-9. doi: 10.1002/j.1460-2075.1993.tb05938.x.
The transient expression of many different genes is mediated by the inducible transcription factor p50-p65 NF kappa B, which in turn is regulated by complex formation with its inhibitor I kappa B alpha. We describe here that in porcine aortic endothelial cells, either IL-1 alpha, TNF alpha or LPS upregulates an inhibitor of NF kappa B which we refer to as ECI-6. ECI-6 is by structural and functional criteria an I kappa B alpha protein, the porcine homologue of MAD-3, pp40 and RL/IF-1. We have studied the promoter of the ECI-6/I kappa B alpha gene and provide three lines of evidence that its expression is directly regulated by NF kappa B. First, the 5' regulatory region of ECI-6/I kappa B alpha contains two sites that bind NF kappa B in electrophoretic mobility shift assays. Second, expression following transfection of an ECI-6/I kappa B alpha promoter-luciferase reporter construct is dependent on a co-transfected NF kappa B-p65 subunit. Third, pretreatment of endothelial cells with antioxidants, agents that inhibit activation of NF kappa B, inhibit the expression of ECI-6/I kappa B alpha. We conclude that the regulated expression of ECI-6/I kappa B alpha could represent a novel feedback mechanism by which NF kappa B downregulates its own activity after transient activation of target genes has been achieved.
许多不同基因的瞬时表达由诱导型转录因子p50-p65核因子κB介导，而该转录因子又通过与其抑制剂IκBα形成复合物来调控。我们在此描述，在猪主动脉内皮细胞中，白细胞介素-1α、肿瘤坏死因子α或脂多糖均可上调一种核因子κB抑制剂，我们将其称为ECI-6。从结构和功能标准来看，ECI-6是一种IκBα蛋白，是MAD-3、pp40和RL/IF-1的猪同源物。我们研究了ECI-6/IκBα基因的启动子，并提供了三条证据表明其表达直接受核因子κB调控。第一，ECI-6/IκBα的5'调控区包含两个在电泳迁移率变动分析中能结合核因子κB的位点。第二，转染ECI-6/IκBα启动子-荧光素酶报告构建体后的表达依赖于共转染的核因子κB-p65亚基。第三，用抗氧化剂（抑制核因子κB激活的试剂）预处理内皮细胞可抑制ECI-6/IκBα的表达。我们得出结论，ECI-6/IκBα的调控表达可能代表一种新的反馈机制，通过该机制，核因子κB在实现靶基因的瞬时激活后下调自身活性。
