Golovnin Anton, Melnikova Larisa, Shapovalov Igor, Kostyuchenko Margarita, Georgiev Pavel
Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334, Moscow, Russia.
Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334, Moscow, Russia.
PLoS One. 2015 Oct 21;10(10):e0140991. doi: 10.1371/journal.pone.0140991. eCollection 2015.
Recent data suggest that insulators organize chromatin architecture in the nucleus. The best studied Drosophila insulator proteins, dCTCF (a homolog of the vertebrate insulator protein CTCF) and Su(Hw), are DNA-binding zinc finger proteins. Different isoforms of the BTB-containing protein Mod(mdg4) interact with Su(Hw) and dCTCF. The CP190 protein is a cofactor for the dCTCF and Su(Hw) insulators. CP190 is required for the functional activity of insulator proteins and is involved in the aggregation of the insulator proteins into specific structures named nuclear speckles. Here, we have shown that the nuclear distribution of CP190 is dependent on the level of EAST protein, an essential component of the interchromatin compartment. EAST interacts with CP190 and Mod(mdg4)-67.2 proteins in vitro and in vivo. Over-expression of EAST in S2 cells leads to an extrusion of the CP190 from the insulator bodies containing Su(Hw), Mod(mdg4)-67.2, and dCTCF. In consistent with the role of the insulator bodies in assembly of protein complexes, EAST over-expression led to a striking decrease of the CP190 binding with the dCTCF and Su(Hw) dependent insulators and promoters. These results suggest that EAST is involved in the regulation of CP190 nuclear localization.
近期数据表明，绝缘子在细胞核中组织染色质结构。研究最为深入的果蝇绝缘子蛋白dCTCF（脊椎动物绝缘子蛋白CTCF的同源物）和Su(Hw)是DNA结合锌指蛋白。含BTB结构域的蛋白Mod(mdg4)的不同异构体与Su(Hw)和dCTCF相互作用。CP190蛋白是dCTCF和Su(Hw)绝缘子的辅助因子。CP190是绝缘子蛋白功能活性所必需的，并且参与绝缘子蛋白聚集成名为核斑点的特定结构。在此，我们已经表明CP190的核分布取决于EAST蛋白的水平，EAST蛋白是染色质间区室的重要组成部分。EAST在体外和体内均与CP190以及Mod(mdg4)-67.2蛋白相互作用。在S2细胞中过表达EAST会导致CP190从含有Su(Hw)、Mod(mdg4)-67.2和dCTCF的绝缘子体中挤出。与绝缘子体在蛋白质复合物组装中的作用一致，EAST过表达导致CP190与dCTCF和Su(Hw)依赖性绝缘子及启动子的结合显著减少。这些结果表明EAST参与CP190核定位的调控。
