Molecular cloning of cDNAs for transcriptional factors of indoleamine 2,3-dioxygenase induced by IFN-gamma

本研究的目的是研究干扰素-γ诱导色氨酸降解酶吲哚-2，3-双加氧酶(IDO)的转录因子。直到1994年，我们已经证明，在所有被研究的人培养细胞系中，干扰素-γ都能诱导出1.7kb和2.3kb两个不同大小的5‘端印花区的IDO mRNAs。基因诱导的动力学和对IDO基因表达5‘控制区的分析表明，1)蛋白质合成的抑制剂阻断了这两种mRNA的诱导，表明需要蛋白质因子的从头合成(S)，2)蛋白质合成发生在加入干扰素-γ后的3小时内，3)1.7kb的mRNA5’端含有IRF-1元件、ISRE元件、Y-box和X-box，但对IDO mRNA的转录没有干扰素-伽玛反应促进活性。1995年，我们在人肺成纤维细胞(HEL)的胞核或胞浆提取液中检测了2.3kb IDO mRNA转录增强元件的调控蛋白(S)的存在，该细胞表现出最高的诱生IDO活性。然而，我们还没有在核提取中检测到这种因素(S)。另一方面，Gupta等人[J Interferon Res.15：517-526(1995)]报道了STAT1和IRF-1都参与了IDO mRNAs的转录，为了证实这一点，正在分析干扰素-γ对STAT1和IRF-1缺陷小鼠的IDO诱导。

The purpose of this study is to characterize the transcriptional factors involved in the IFN-gamma-mediated induction of indoleamine 2,3-dioxygenase (IDO), a tryptophan degrading enzyme. Until 1994, we have demonstrated that two IDO mRNAs, 1.7kb and 2.3kb, whch differ in size of 5' franking region are induced by IFN-gamma in all human cultured cell lines examined. Kinetics of both mRNA induction and analyzes of the 5' control region of IDO gene expression have shown that 1) induction of both mRNAs are blocked by inhibitors for protein synthesis, indicating the need for a de novo synthesis of protein factor (s), 2) the protein synthesis occurs within 3 h after the addition of IFN-gamma, 3) the 5' region of 1.7kb mRNA that contains IRF-1 element, ISRE element, a Y-box, and a X-box but has no IFN-gamma-responsive promoting activity for transcription of IDO mRNA,and 4) the 5' region of 2.3kb mRNA has an ISRE and a X-box with the IFN-gamma responsive enhancing activity.In 1995, we have examined the presence of regulatory protein (s) for the enhance element for transcription of 2.3kb IDO mRNA in nuclear or cytoplasmic extract of human lung fibroblasts (HEL), which exhibited the highest induction of IDO by the addition of IFN-gamma. However, we have not yet detect such factor (s) in the nuclear extract. On the other hand, Gupta et al [J Interferon Res.15 : 517-526 (1995)] have reported that both STAT1 and IRF-1 are involved in the transcription of IDO mRNA.To confirm this, analysis of IDO induction by IFN-gamma in STAT1 and IRF-1 deficient mice is in progress.