Analysis of the structure of interleukin 1 receptor and the mechanism of IL-1 signal transduction

在Jurkat T细胞系中，研究了小鼠白细胞介素1受体（IL-1 R）I型的细胞内部分与人IL-8基因活化的结构和功能关系。我们发现受体功能的C-末端边界位于距C-末端28-42个氨基酸之间，并且IL-1 R胞质部分的大区域是传递IL-1信号的功能所必需的。此外，IL-1 R的胞质区具有与gp 130同源的区段，IL-6 R的β链，包括盒1和盒2样元件，以及gp 130同源区段内的突变，消除了诱导IL-8基因表达的能力，提示几种细胞因子受体的胞质部分具有相似的结构要求。1受体介导的信号转导，我们检测了人IL-8基因5 ′侧翼区的IL-1应答元件。我们发现IL-8启动子上的三个顺式元件，NF κ B，C/EBP和AP-1结合位点是IL-1诱导IL-8基因活化所必需的。有趣的是，在纤维肉瘤8387细胞中，NF κ B和C/EBP结合位点对于对IL-1的反应性是必需的，而在胃癌衍生的MKN 45细胞中，AP-1和NF κ B结合位点是必不可少的，这表明这三个位点的相对重要性在细胞类型中是不同的。此外，观察到TNF和IFN γ之间对于IL-8产生和IL-8启动子活化的协同作用。凝胶阻滞分析显示，TNF和IFN γ协同诱导NF κ B结合活性的活化，表明IFN γ通过增强NF κ B活化来增强TNF对IL-8基因的活化。

The structural and functional relaionship of the intracellular portion of mouse interleukin 1 receptor (IL-1R)type I was examined with regard to activation of the human IL-8 gene in the Jurkat T cell line. We found that C-terminal boundary for the function of the receptor is localized between 28-42 amino acids from C-terminal end, and that the large region of IL-1R cytoplasmic portion is required for the function to transmit IL-1 signal. In addition, the cytoplasmic region of IL-1R possess the segment homologous to gp130, beta chain of IL-6R, including box 1 and 2-like elements, and mutations within the gp130 homologous segments, abolishied the capacity to induce IL-8 gene expression, suggesting similar structural requirements in the cytoplasmic portion of several cytokine receptors.To investigate the molecular mechanism of IL-1 reaceptor mediated signal transduction, we examined the IL-1 responsive elements on the 5'-flanking region of the human IL-8 gene. We found that the three cis elements on the IL-8 promoter, NFkB, C/EBP and AP-1 binding sites are required for IL-1 induced IL-8 gene activation. Interestingly, in fibrosarcoma 8387 cells, NFkB and C/EBP binding sites are necessary for the responsiveness to IL-1, whereas in gastric cancer derived MKN45 cells, AP-1 and NFkB binding sites, are indispensable, indicationg that the relative importance of these three sites is different among cell types. In addition synergistic action between TNF and IFNgamma was observed for the IL-8 production and the activation of IL-8 promoter. Gel retardation analysis revealed that TNF and IFNgamma synergistically induced the activation of NFkB binding activity, suggesting that IFNgamma enhance the activation of IL-8 gene by TNF through augmenting NFkB activation.