Pitha P M, Ciufo D M, Kellum M, Raj N B, Reyes G R, Hayward G S
Proc Natl Acad Sci U S A. 1982 Jul;79(14):4337-41. doi: 10.1073/pnas.79.14.4337.
Human genomic DNA and plasmids carrying portions of the cDNA gene for human beta-interferon have been introduced into mouse Ltk- cells by cotransfection with a herpes simplex virus thymidine kinase (TK) gene. One plasmid contains 840 base pairs of human DNA complementary to pre-beta-interferon mRNA inserted into pBR322, whereas the other plasmids have hybrid genes containing only the 560-base pair coding region inserted under the transcriptional control of the TK promoter. Constitutive interferon production could not be detected in any of the mouse TK+ cell lines tested. Nevertheless, synthesis of interferon could be induced by poly(rI . rC) treatment in at least 16 of these cell lines, including clones transfected with genomic DNA, the beta-interferon cDNA, and the TK-beta-interferon cDNA hybrid gene. The interferon produced was specific for human cells and could be neutralized by antiserum against human beta-interferon. In contrast to human fibroblast cells, in which the synthesis of induced beta-interferon is transient, the poly(rI . rC)-induced TK+ lines continued to produce beta-interferon for prolonged periods of time and did not respond to superinduction conditions. Therefore, in transfected mouse cells, the coding DNA sequence from the human beta-interferon gene, without any of the adjacent 3' or 5' flanking human DNA sequences, was sufficient both to direct synthesis of biologically active product and to respond to the specific induction system that operates in human cells. However, the mechanism that switches off the synthesis of induced interferon in human cells appears not to operate in mouse cells transfected with beta-interferon cDNA.
通过与单纯疱疹病毒胸苷激酶（TK）基因共转染，已将携带人β-干扰素cDNA基因部分片段的人基因组DNA和质粒导入小鼠Ltk-细胞。一种质粒含有插入pBR322的840个碱基对的与人前β-干扰素mRNA互补的人DNA，而其他质粒具有杂种基因，其仅包含在TK启动子转录控制下插入的560个碱基对的编码区。在所测试的任何小鼠TK+细胞系中均未检测到组成型干扰素产生。然而，在这些细胞系中的至少16个中，包括用基因组DNA、β-干扰素cDNA和TK-β-干扰素cDNA杂种基因转染的克隆，可通过聚（rI·rC）处理诱导干扰素合成。产生的干扰素对人细胞具有特异性，并且可被抗人β-干扰素抗血清中和。与诱导的β-干扰素合成是短暂的人成纤维细胞相反，聚（rI·rC）诱导的TK+细胞系持续长时间产生β-干扰素，并且对超诱导条件无反应。因此，在转染的小鼠细胞中，来自人β-干扰素基因的编码DNA序列，没有任何相邻的3'或5'侧翼人DNA序列，足以指导生物活性产物的合成并响应在人细胞中起作用的特定诱导系统。然而，在人细胞中关闭诱导干扰素合成的机制似乎在转染了β-干扰素cDNA的小鼠细胞中不起作用。
