Klein S B, Yeivin A, Becker G, Taylor M W
Department of Biology, Indiana University, Bloomington.
J Interferon Res. 1994 Dec;14(6):333-41. doi: 10.1089/jir.1994.14.333.
Genetic analyses of mutants have yielded valuable information about p91-associated interferon signal transduction. It was thus discovered that p91 is an essential protein for the induction of both type I and type II interferons. We previously reported the development of ME180 mutants resistant to interferon-gamma because of a signaling defect resulting in the loss of IDO induction. IDO does not respond to type I interferon despite an ISRE-like sequence upstream of the coding region. However, the IDO mutants were found to be cross-resistant to the growth-inhibitory effects of type I interferon. We therefore examined the effects of both types of interferon on interferon-stimulated gene mRNA accumulation and examined alterations in cellular protein introduced by the mutation. The induction of the p91-responsive gene 6-16 was not altered in either of the mutants, and the early-induced gene IRF1 exhibited differences only in the kinetics of mRNA accumulation. The later induced gene, p68, also exhibited different kinetics, possibly reflecting the changes in IRF1. Immunoprecipitated p91 exhibited normal, interferon-induced phosphorylation in both mutants. Two-dimensional gel electrophoresis revealed that the mutant cells contained 20 peptides with altered biochemistry. These results suggest that IDO induction is controlled by a distinct set of proteins not directly correlated with p91 activation.
对突变体的基因分析已经产生了关于p91相关干扰素信号转导的有价值信息。由此发现，p91是诱导I型和II型干扰素所必需的蛋白质。我们之前报道了ME180突变体的产生，该突变体由于信号缺陷导致IDO诱导缺失而对干扰素-γ具有抗性。尽管编码区上游存在类似ISRE的序列，但IDO对I型干扰素无反应。然而，发现IDO突变体对I型干扰素的生长抑制作用具有交叉抗性。因此，我们研究了两种类型干扰素对干扰素刺激基因mRNA积累的影响，并研究了突变引入的细胞蛋白的变化。在任何一种突变体中，p91反应基因6-16的诱导都没有改变，早期诱导基因IRF1仅在mRNA积累动力学方面表现出差异。后期诱导基因p68也表现出不同的动力学，这可能反映了IRF1的变化。在两种突变体中，免疫沉淀的p91均表现出正常的、干扰素诱导的磷酸化。二维凝胶电泳显示，突变体细胞含有20种生化性质改变的肽。这些结果表明，IDO的诱导受一组与p91激活不直接相关的独特蛋白质的控制。
