Interferon‐induced binding of nuclear factors to promoter elements of the 2‐5A synthetase gene.
Interferon‐induced binding of nuclear factors to promoter elements of the 2‐5A synthetase gene.
复制标题
干扰素诱导核因子与 2-5A 合成酶基因启动子元件的结合。
作者：
M. Rutherford;G E Hannigan;B. R. Williams
检测了人类 2-5A 合成酶基因 5' 侧翼序列片段对干扰素 α (IFN) 的反应能力。猴细胞中的瞬时转染测定表明，IFN 调节转录所需序列的 5' 边界最多为假定的翻译起始密码子上游 155 个核苷酸。该序列的 3' 边界位于多个转录起始位点的区域内，前面没有明显的 TATA 盒。使用源自该 IFN 响应序列的 40 bp 探针进行的结合测定，使用从人和猴细胞制备的核提取物证明了三个 IFN 调节的 DNA 因子条带移动的存在。 IFN 在人类细胞中诱导这些复合物的动力学与之前观察到的 IFN 对 2-5A 合成酶基因转录激活的动力学非常相似。体内竞争测定表明，结合 IFN 调节因子的相同 40 bp 区域可以降低共转染 2-5A 合成酶启动子的 IFN 诱导活性；该片段，无论其方向如何，都可以赋予异源启动子IFN诱导能力。
Fragments of the 5′‐flanking sequence of a human 2‐5A synthetase gene were assayed for their ability to respond to interferon‐alpha (IFN). Transient transfection assays in monkey cells demonstrated that the 5′ boundary of the sequence required for IFN‐regulated transcription is, at most, 155 nucleotides upstream from the presumed translational initiation codon. The 3′ boundary of this sequence lies within a region of multiple transcription start sites preceded by no obvious TATA box. Binding assays, using a 40‐bp probe derived from this IFN‐responsive sequence, demonstrated the presence of three IFN‐modulated, DNA‐factor band shifts using nuclear extracts prepared from human and monkey cells. The induction of these complexes in human cells by IFN occurs with kinetics which closely parallel those previously observed for the transcriptional activation of the 2‐5A synthetase gene by IFN. In vivo competition assays showed that the same 40‐bp region which bound IFN‐modulated factors could decrease the IFN‐induced activity of a co‐transfected 2‐5A synthetase promoter; this fragment, regardless of its orientation, could confer IFN‐inducibility on a heterologous promoter.