Sleigh M J, Lockett T J, Kelly J, Lewy D
Nucleic Acids Res. 1987 May 26;15(10):4307-24. doi: 10.1093/nar/15.10.4307.
DNA competition studies have been used to investigate the presence of a repressor of viral enhancer function in F9 mouse embryonal carcinoma cells. The complete polyoma virus enhancer region, cotransfected into F9 cells with the SV40 promoter/enhancer attached to a chloramphenicol acetyl transferase marker gene, induced a small increase in pSV2CAT expression. This can be explained by preferential but weak binding by polyoma sequences of a molecule repressing pSV2CAT transcription. Repressor activity substantially disappeared when the cells were induced to differentiate by retinoic acid. Repressor binding was localised to one half of the polyoma enhancer, but was lost on further fragmentation of this region. It appears that multiple sequence elements may be required for repressor binding and that these are at least partially separable from the complement of elements binding enhancer activating molecules.
DNA竞争研究已被用于调查F9小鼠胚胎癌细胞中病毒增强子功能阻遏物的存在情况。完整的多瘤病毒增强子区域，与连接氯霉素乙酰转移酶标记基因的SV40启动子/增强子共转染到F9细胞中，诱导pSV2CAT表达略有增加。这可以通过多瘤序列对抑制pSV2CAT转录的分子的优先但弱结合来解释。当细胞用视黄酸诱导分化时，阻遏物活性基本消失。阻遏物结合定位于多瘤增强子的一半，但在该区域进一步片段化时丧失。似乎阻遏物结合可能需要多个序列元件，并且这些元件至少部分地与结合增强子激活分子的元件互补物分开。
