Reich N, Evans B, Levy D, Fahey D, Knight E, Darnell J E
Proc Natl Acad Sci U S A. 1987 Sep;84(18):6394-8. doi: 10.1073/pnas.84.18.6394.
A human gene encoding an interferon-induced 15-kDa protein has been isolated from a genomic library. The gene appears to be single-copy and is composed of two exons, the first of which contains the ATG translation initiation codon. In vitro nuclear run-on assays showed that the transcription rate of the gene is stimulated after interferon treatment. To analyze transcriptional regulatory sequences, we constructed recombinant plasmids for use in transient transfection assays of HeLa cells. Constructs containing 115 nucleotides 5' to the transcription initiation site were found to be fully inducible by interferon. Assays of deletion mutants identified a critical element for interferon induction located between -115 and -96, just upstream of the "CCAAT box." Moreover, a DNA fragment including this region can confer interferon inducibility on a heterologous promoter (thymidine kinase) when cloned in either orientation upstream of the gene or downstream of the gene. These are properties characteristic of an enhancer element that is active only after treatment with interferon. This regulatory sequence may be shared by a group of interferon-induced genes, since a very similar sequence is present within the functional region near the RNA start site of another interferon-induced gene.
从基因组文库中分离出了一个编码干扰素诱导的15 kDa蛋白的人类基因。该基因似乎是单拷贝的，由两个外显子组成，其中第一个外显子包含ATG翻译起始密码子。体外细胞核连续转录分析表明，干扰素处理后该基因的转录速率受到刺激。为了分析转录调控序列，我们构建了用于HeLa细胞瞬时转染分析的重组质粒。发现含有转录起始位点上游115个核苷酸的构建体可被干扰素完全诱导。缺失突变体分析确定了位于“CCAAT盒”上游-115至-96之间的干扰素诱导关键元件。此外，包含该区域的DNA片段在基因上游或基因下游以任一方向克隆时，可赋予异源启动子（胸苷激酶）干扰素诱导性。这些是仅在干扰素处理后才具有活性的增强子元件的特征。由于在另一个干扰素诱导基因的RNA起始位点附近的功能区域内存在非常相似的序列，因此该调控序列可能为一组干扰素诱导基因所共有。
