Ko M S, Takahashi N, Sugiyama N, Takano T
Furusawa MorphoGene Project, Research Development Corporation of Japan, Tsukuba.
Gene. 1989 Dec 14;84(2):383-9. doi: 10.1016/0378-1119(89)90512-x.
A new gene expression system in mammalian cells was developed by using the glucocorticoid receptor (GR) as an inducible positive feedback factor. Mouse Ltk- cells were transfected with plasmids carrying the GR-encoding gene and the lacZ reporter gene, both of which were fused with the glucocorticoid-inducible enhancer/promotor of the mouse mammary tumor virus (MTV). The GR gene was first induced to supply the receptor protein, which further induced the expression of both GR and reporter genes. Stable transformants induced with dexamethasone, a synthetic glucocorticoid hormone, demonstrated beta-galactosidase activity 60-140-fold higher than uninduced controls. Similarly, the human alpha-interferon-encoding gene fused with the MTV enhancer/promoter was induced more than 12,000-fold. This system allowed us to increase the expression of the reporter or target genes without augmenting basal levels of expression significantly, and may be useful to investigate the unknown function of a cloned gene, particularly when the gene product of interest is cytotoxic or growth-inhibiting.
通过使用糖皮质激素受体（GR）作为诱导性正反馈因子，在哺乳动物细胞中开发了一种新的基因表达系统。用携带GR编码基因和lacZ报告基因的质粒转染小鼠Ltk-细胞，这两个基因均与小鼠乳腺肿瘤病毒（MTV）的糖皮质激素诱导增强子/启动子融合。首先诱导GR基因以提供受体蛋白，该受体蛋白进一步诱导GR和报告基因的表达。用地塞米松（一种合成的糖皮质激素）诱导的稳定转化体显示出β-半乳糖苷酶活性比未诱导的对照高60至140倍。同样，与MTV增强子/启动子融合的人α-干扰素编码基因被诱导了超过12000倍。该系统使我们能够在不显著增加基础表达水平的情况下增加报告基因或靶基因的表达，并且可能有助于研究克隆基因的未知功能，特别是当感兴趣的基因产物具有细胞毒性或生长抑制作用时。
