摘要目的 探讨干扰素α(IFN-α)调控维甲酸诱导基因G(RIG-G)表达调控的分子机制.方法 采用Western blot方法检测急性早幼粒白血病细胞系NB4经IFN-α处理后信号传导和转录活化因子1(STAT1)、p-STAT1和RIG-G蛋白的表达变化.采用细胞转染、报告基因实验、免疫共沉淀实验和染色质免疫沉淀实验等技术,研究STAT1缺失的U3A细胞中,STAT1、STAT2和IFN调节因子9(IRF-9)在IFN-α调控RIG-G基因表达中的作用及其机制.结果 在 U3A 细胞中,只有当STAT2和IRF-9共同转染时,RIG-G启动子荧光素酶报告基因的表达活性才明显升高,约为空载对照组的8倍.在无IFN-α作用时,野生型或突变型STAT2与IRF-9共同转染U3A细胞可产生相似的效应;但IFN-α能进一步增强野生型STAT2与IRF-9的转录激活作用,约为未加IFN-α时的6倍,而对突变型STAT2无效.STAT2能与IRF-9相互作用,并能与RIG-G基因的启动子结合.结论 STAT2和IRF-9能以不依赖于STAT1的形式发生相互作用,所形成的复合物是介导IFN-α调控RIG-G基因表达的关键性转录因子,这是一种有别于经典JAK-STAT途径的新的干扰素信号转导方式.

abstractsObjective To investigate the molecular mechanisms by which IFN-α regulated retinoic acid-induced gene G (RIG-G) expression. Methods The expression of STAT1, p-STAT1 and RIG-G in IFN-α-treated NB4 cells was detected by Westem blot. The roles of STAT1, STAT2 and IRF-9 in IFN-α-induced RIG-G expression were analyzed in STAT1-null U3A cells by cell transfection, reporter gene assay, co-immunoprecipitation and chromatin immunoprecipitaion. Results In U3A cells, only when STAT2 and IRF-9 were co-transfected, the luciferase activities of RIG-G promoter-containing reporter gene could be highly increased about 8-fold compared with that in the control group. Moreover, in the absence of IFN-α,similar effects were observed in either IRF-9 co-transfected with wild type or mutant form of STAT2, whereas IFN-α could increase the transactivation activity of wild type STAT2 and IRF-9 by 6-fold compared with that without IFN-α, but had no effect on mutant STAT2. In addition, STAT2 could interact with IRF-9 and bind to the RIG-G promoter. Conclusion STAT2 may interact with IRF-9 in a STAT1-independent manner. The complex STAT2/IRF-9 is the key factor mediating the expression of RIG-G gene regulated by IFN-α. This is a novel signal transduction cascade for IFN which is different from the classical JAK-STAT pathway.