INDUCTION OF NF-KB AFTER EXPOSURE OF LYMPHOID CELLS TO SOLUBLE TAX1

HTLV-I Tax1蛋白在病毒和细胞基因中的作用 在受感染细胞中的调节，从受感染细胞释放到 发挥细胞外细胞因子的作用。事实证明， 纯化的胞外Tax1蛋白诱导核内聚集 淋巴样细胞中的核因子-kB结合活性。由于HTLV-I感染导致 淋巴毒素(TNF-β)和免疫球蛋白分泌水平增加， Tax1刺激的细胞中的核因子-kB蛋白与细胞因子的相互作用 分析了肿瘤坏死因子-α和免疫球蛋白-kappa(IgK)轻链基因。 在环己亚胺存在的情况下，Tax1诱导了核因子-kB的表达。税费1 刺激不会导致核因子-kB或c-rel RNA水平的升高。 这些结果表明，核因子-kB蛋白的新合成不是 是诱导核因子-kB结合活性所必需的。使用Igk核因子-kB 以结合部位为探针，发现了两个不同的核因子-kB凝胶位移复合体 由Tax1蛋白诱导。对凝胶位移络合物的分析表明 它们受到不同的抑制蛋白的调节。核因子-kB 与共同的核因子-kB结合位点相互作用的蛋白质 免疫球蛋白和肿瘤坏死因子-β启动子明显不同。Tax1刺激导致 逆转录测法测定肿瘤坏死因子-β和免疫球蛋白基因的表达水平 转录和聚合酶链式反应分析。这些结果代表了第一个 细胞外Tax1可调节其表达的实验证据 内源性细胞基因。

HTLV-I Tax1, in addition to the protein's role of viral and cellular gene regulation in the infected cell, is released from the infected cell to act as an extracellular cytokine. It has been demonstrated that purified, extracellular Tax1 protein induced the nuclear accumulation of NF-kB binding activity in lymphoid cells. Since HTLV-I infection causes increased levels of lymphotoxin (TNF-beta) and immunoglobulin secretion, the interaction of NF-kB proteins from Tax1- stimulated cells with the TNF-~ and immunoglobulin kappa (Igk) light chain genes has been analyzed. Tax1 induction of NF-kB occurred in the presence of cyclo-heximide. Tax1 stimulation did not result in increased levels of NF-kB or c-rel RNA. These results indicate that new synthesis of NF-kB proteins was not required for induction of NF-kB binding activity. Using the Igk NF-kB binding site as a probe, two distinct NF-kB gel shift complexes were induced by the Tax1 protein. Analysis of the gel shift complexes suggest that they are regulated by distinct inhibitor proteins. The NF-kB proteins that interacted with the consensus NF-kB binding sites in the Igk and TNF-beta promoter were distinct. Tax1 stimulation led to increased levels of TNF-beta and Igk mRNA as measured by reverse transcription and PCR analysis. These results represent the first experimental evidence that extracellular Tax1 can regulate the expression of endogenous cellular genes.