Green M R, Treisman R, Maniatis T
Cell. 1983 Nov;35(1):137-48. doi: 10.1016/0092-8674(83)90216-7.
When the human beta-globin gene is transfected into Hela cells, no beta-globin RNA is detected unless the gene is linked to a viral transcription enhancer. In this paper we show that trans-acting adenovirus and herpesvirus (pseudorabies) transcriptional regulatory proteins can circumvent this enhancer requirement for detectable beta-globin transcription in transient expression assays. The viral gene products can be provided by constitutively expressed, integrated viral genes in established cell lines, by viral infection of permissive cells, or by transfection of cells with bacterial plasmids carrying the viral immediate-early genes. These results demonstrate the utility of transient expression assays for studying regulatory mechanisms involving trans-acting factors. Analysis of beta-globin promoter mutants indicates that between 75 and 128 bp of sequence 5' to the mRNA cap site is required for enhancer-dependent transcription in Hela cells. In contrast, beta-globin transcription in the presence of viral immediate-early gene products requires only 36 bp of 5'-flanking sequence, which includes the TATA box. Thus both cis and trans-acting viral factors activate beta-globin gene transcription in transient expression experiments, but the mechanisms by which they act appear to be fundamentally different.
当人类β-珠蛋白基因转染到Hela细胞中时，除非该基因与病毒转录增强子相连，否则检测不到β-珠蛋白RNA。在本文中，我们表明在瞬时表达试验中，反式作用的腺病毒和疱疹病毒（伪狂犬病）转录调节蛋白可以规避检测到β-珠蛋白转录对增强子的需求。病毒基因产物可以由已建立细胞系中组成型表达的整合病毒基因提供，由允许细胞的病毒感染提供，或通过用携带病毒立即早期基因的细菌质粒转染细胞提供。这些结果证明了瞬时表达试验在研究涉及反式作用因子的调节机制方面的实用性。对β-珠蛋白启动子突变体的分析表明，在Hela细胞中，增强子依赖性转录需要mRNA帽位点5'端75至128 bp的序列。相比之下，在病毒立即早期基因产物存在的情况下，β-珠蛋白转录仅需要36 bp的5'侧翼序列，其中包括TATA框。因此，在瞬时表达实验中，顺式和反式作用的病毒因子都能激活β-珠蛋白基因转录，但它们的作用机制似乎有根本的不同。
