Wang Q, Floyd-Smith G
Molecular and Cellular Biology Program and Department of Biology, Arizona State University, Tempe, AZ 85287-1501, USA.
Gene. 1998 Nov 5;222(1):83-90. doi: 10.1016/s0378-1119(98)00476-4.
The human 2', 5'-oligoadenylate (2-5A) synthetases are members of a family interferon (IFN)-inducible anti-viral proteins. Three size classes of these enzymes: small (p40, p46), intermediate (p69, p71) and large (p100), are encoded by three genes that exhibit differential constitutive and IFN-inducible expression. Since the 5'-regulatory region of the 69 kDa isoform contains multiple putative control elements, deletion analysis and site directed mutagenesis were done to identify key regulatory motifs. The region located between bp -972 and -452 from the translational start site contains elements that slightly repress constitutive and IFN-inducible transcription. The region from bp -366 to -117 contains two positive regulatory elements that differ slightly from consensus IFN-regulated factor 1 (IRF-1) binding sites. In mobility shift assays, the proximal IRF-1 site weakly binds a novel factor found in both control and IFN-treated cells. The region from bp -117 to -10 contains a functional interferon stimulated response element (ISRE) that contributes to constitutive expression and confers IFN-inducibility on a heterologous promoter. The ISRE specifically binds an IFN-inducible factor that contains signal transducer activator of transcription (STAT) 1alpha. The ISRE and the two IRF-1-like sites cooperatively interact to control transcription. These three elements are sufficient for constitutive and IFN-inducible expression, since expression from reporter constructs containing mutations in all three elements is low in both control and IFN-treated cells.
人类2',5'-寡腺苷酸（2-5A）合成酶是干扰素（IFN）诱导的抗病毒蛋白家族成员。这些酶有三种大小类型：小（p40、p46）、中（p69、p71）和大（p100），由三个基因编码，这些基因表现出不同的组成型和IFN诱导型表达。由于69 kDa同工型的5'-调控区包含多个假定的控制元件，因此进行了缺失分析和定点诱变以鉴定关键调控基序。从翻译起始位点起位于-972至-452碱基对之间的区域含有略微抑制组成型和IFN诱导型转录的元件。从-366至-117碱基对的区域含有两个正向调控元件，它们与共有IFN调节因子1（IRF-1）结合位点略有不同。在凝胶迁移试验中，近端IRF-1位点与在对照细胞和IFN处理细胞中均发现的一种新因子弱结合。从-117至-10碱基对的区域含有一个功能性干扰素刺激反应元件（ISRE），它有助于组成型表达并赋予异源启动子IFN诱导性。ISRE特异性结合一种含有信号转导转录激活因子（STAT）1α的IFN诱导因子。ISRE和两个IRF-1样位点协同相互作用以控制转录。这三个元件足以实现组成型和IFN诱导型表达，因为在对照细胞和IFN处理细胞中，含有这三个元件均发生突变的报告基因构建体的表达都很低。
