Molecular cloning of trans-acting factor cDNA for IFN-gamma-inducible indoleamine 2,3-dioxygenase

直到1992年，我们使用IDO cDNA作为探针，从人类基因组DNA文库中分离出ifn - γ诱导的色氨酸降解酶吲哚胺2,3-双加氧酶（IDO）的基因，并测定了它们的限制性内切图和部分核苷酸序列。5'侧区包含ifn刺激反应元件（ISRE）和X-box样序列。这些序列具有促进IDO mRNA转录的活性。ifn - γ介导的IDO mRNA的产生被蛋白质合成抑制剂抑制，表明新合成的蛋白质参与了mRNA的诱导。蛋白在加入ifn - γ后的3h内合成。1993年，我们在人肺成纤维细胞（HEL）的核或细胞质提取物中检测了IDO mRNA转录增强子元件（ISRE和X-box）的反式作用蛋白的存在，发现添加ifn - γ对IDO的诱导最高。另一方面，酪氨酸激酶抑制剂herbimycin A强烈抑制IDO基因的表达，提示酪氨酸激酶参与了酶的诱导。Northern blotting分析表明，除了胎盘、肺和小肠外，人IDO基因在胸腺中也大量表达。

Until 1992, we have isolated the gene of indoleamine 2,3-dioxygenase (IDO), an IFN-gamma-inducible tryptophan degrading enzyme, from human genomic DNA library using the IDO cDNA as a probe, and their restriction maps and partial nucleotide sequences were determined. The 5' flanking region contains IFN-stimulated response element (ISRE) and X-box like sequences. These sequences have a promoting activity for transcription of IDO mRNA.The IFN-gamma-mediated production of the IDO mRNA was suppressed by protein synthesis inhibitors, indicating an involvement of protein(s) newly synthesized in the induction of mRNA.The synthesis of the protein(s) occurred within 3h after the addition of IFN-gamma.In 1993, we have examined the presence of trans-acting protein(s) for the enhancer element (ISRE and X-box) for transcription of 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. On the other hand, the expression of IDO gene was inhibited strongly by herbimycin A, an inhibitor for tyrosine kinase, suggesting an implication of a tyrosine kinase in the enzyme induction. Northern blotting analysis indicated that the human IDO gene is expressed abundantly in the thymus in addition to the placenta, lung, and small intestine.