Gariglio G, Panico S, Gribaudo G, Martinotti M G, Cavallo G, Landolfo S
Institute of Microbiology, Medical School, University of Torino, Italy.
J Biol Regul Homeost Agents. 1991 Jul-Sep;5(3):107-11.
When treated with IFN-alpha, NIH-3T3 cells express after a few hours high levels of the mouse 202 gene mRNA. This activation takes place at the transcriptional level as shown by nuclear "run on" assay. For this purpose a fragment of 806 base-pairs (the b fragment), spanning the 5'-flanking region of the 202 gene, was linked to the reporter CAT gene and transiently transfected into mouse NIH 3T3. The data suggest that the b fragment is sufficient to confer transcriptional inducibility upon IFN stimulation and can account in large part for the response of the 202 gene. Binding assays, using a 40-bp probe derived from the IFN-stimulated response element (ISRE) comprised in the b fragment, demonstrated the presence of two DNA-binding proteins. One of these, defined as complex A, was inducible upon IFN treatment, whereas the other, defined as complex B, was constitutively present regardless of IFN treatment. The IFN-alpha-induced complex A appears to have the necessary characteristics to be the transcriptional activator of the 202 gene: it requires the same nucleotides for binding as are required for IFN-dependent gene activation and is dependent on IFN-alpha treatment.
用α-干扰素处理时，NIH-3T3细胞在数小时后会表达高水平的小鼠202基因mRNA。如细胞核“连续标记”试验所示，这种激活发生在转录水平。为此，将一段806个碱基对的片段（b片段），其跨越202基因的5'-侧翼区域，与报告基因氯霉素乙酰转移酶（CAT）基因连接，并瞬时转染到小鼠NIH 3T3细胞中。数据表明，b片段足以赋予干扰素刺激后的转录诱导性，并且在很大程度上可以解释202基因的反应。使用来自b片段中包含的干扰素刺激反应元件（ISRE）的40个碱基对的探针进行的结合试验，证明存在两种DNA结合蛋白。其中一种被定义为复合物A，在干扰素处理后可被诱导，而另一种被定义为复合物B，无论是否进行干扰素处理均持续存在。α-干扰素诱导的复合物A似乎具有成为202基因转录激活剂的必要特征：它结合所需的核苷酸与干扰素依赖性基因激活所需的核苷酸相同，并且依赖于α-干扰素处理。
