Kyrchanova Olga, Chetverina Darya, Maksimenko Oksana, Kullyev Andrey, Georgiev Pavel
Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
Nucleic Acids Res. 2008 Dec;36(22):7019-28. doi: 10.1093/nar/gkn781. Epub 2008 Nov 5.
Insulators are defined as a class of regulatory elements that delimit independent transcriptional domains within eukaryotic genomes. According to previous data, an interaction (pairing) between some Drosophila insulators can support distant activation of a promoter by an enhancer. Here, we have demonstrated that pairs of well-studied insulators such as scs-scs, scs'-scs', 1A2-1A2 and Wari-Wari support distant activation of the white promoter by the yeast GAL4 activator in an orientation-dependent manner. The same is true for the efficiency of the enhancer that stimulates white expression in the eyes. In all insulator pairs tested, stimulation of the white gene was stronger when insulators were inserted between the eye enhancer or GAL4 and the white promoter in opposite orientations relative to each other. As shown previously, Zw5, Su(Hw) and dCTCF proteins are required for the functioning of different insulators that do not interact with each other. Here, strong functional interactions have been revealed between DNA fragments containing binding sites for either Zw5 or Su(Hw) or dCTCF protein but not between heterologous binding sites [Zw5-Su(Hw), dCTCF-Su(Hw), or dCTCF-Zw5]. These results suggest that insulator proteins can support selective interactions between distant regulatory elements.
绝缘子被定义为一类调控元件,其在真核生物基因组中界定独立的转录结构域。根据先前的数据,一些果蝇绝缘子之间的相互作用(配对)能够支持增强子对启动子的远距离激活。在此,我们已经证明,像scs-scs、scs'-scs'、1A2-1A2和Wari-Wari这样经过充分研究的绝缘子对,能够以方向依赖的方式支持酵母GAL4激活因子对白色启动子的远距离激活。刺激眼睛中白色表达的增强子的效率也是如此。在所有测试的绝缘子对中,当绝缘子以彼此相反的方向插入眼睛增强子或GAL4与白色启动子之间时,对白色基因的刺激更强。如先前所示,Zw5、Su(Hw)和dCTCF蛋白是相互不作用的不同绝缘子发挥功能所必需的。在此,已经揭示了含有Zw5或Su(Hw)或dCTCF蛋白结合位点的DNA片段之间存在强烈的功能相互作用,但异源结合位点[Zw5-Su(Hw)、dCTCF-Su(Hw)或dCTCF-Zw5]之间不存在这种相互作用。这些结果表明,绝缘子蛋白能够支持远距离调控元件之间的选择性相互作用。