Gariglio M, Gaboli M, Mana C, Foresta P, Ying G G, Angeretti A, Lembo D, Landolfo S
Medical School of Novara, University of Turin, Italy.
New Microbiol. 1994 Oct;17(4):259-67.
When treated with IFN-alpha, L1210 leukemia cells express high levels of the mouse 202 gene mRNA after a few hours. Three tandem copies of a 43 bp fragment (GAbox) homologous to the IFN-stimulatable response element (ISRE), located in the 5'-flanking region of the 202 gene, were linked to the reporter CAT gene and transiently transfected into L1210 cells. The data suggest that the GA box is sufficient to confer transcriptional inducibility upon IFN stimulation. Binding assays, using the labeled GA box as a probe, demonstrated the presence of a retarded complex, designated GAbfl, in the nuclear extracts of L1210 cells treated with IFN-alpha. This complex is absent in the extracts of L1210 cells treated with ssRNA viruses or synthetic dsRNA. Moreover, photoaffinity cross-linking experiments revealed that GAbfl contains a protein of about 50 kDa. Altogether these results demonstrate that antiviral state induction by IFN-alpha in L1210 cells is preceded by GAbfl binding to the ISRE of the IFN-inducible genes.
用α-干扰素处理时，L1210白血病细胞在数小时后会高水平表达小鼠202基因的mRNA。位于202基因5'侧翼区域的、与干扰素刺激反应元件（ISRE）同源的43 bp片段（GA盒）的三个串联拷贝，与报告基因氯霉素乙酰转移酶（CAT）相连，并瞬时转染到L1210细胞中。数据表明，GA盒足以赋予干扰素刺激后的转录诱导能力。使用标记的GA盒作为探针的结合试验表明，在用α-干扰素处理的L1210细胞核提取物中存在一种滞后复合物，命名为GAbfl。在用单链RNA病毒或合成双链RNA处理的L1210细胞提取物中不存在这种复合物。此外，光亲和交联实验表明，GAbfl含有一种约50 kDa的蛋白质。这些结果共同表明，α-干扰素在L1210细胞中诱导抗病毒状态之前，GAbfl会与干扰素诱导基因的ISRE结合。
