Developmental control of gene silencing

项目摘要 共享一个共同基因组的细胞转录其可用基因的子集以执行不同的功能。 多梳组蛋白（Polycomb-group，PcG）通过结合和化学修饰染色质而促进细胞特化 在低转录基因周围，以进一步减少（“沉默”）它们的表达。尽管许多PcG蛋白具有 虽然已经被确认，但神秘的是它们功能中最有趣的方面。沉默的效用来自于 选择性的强加。然而，未知的机制决定了沉默何时开始或结束， 正常发展。此外，PcG蛋白如何在表观遗传学上与不同的靶基因相关联， 对不同细胞的了解很少。解决这些问题很重要，因为沉默错误会破坏 发展和促进人类癌症。拟议的研究计划使用了一个新的模型系统， 果蝇保育细胞分化，以及研究沉默如何发生的新的遗传和基因组工程工具 起始、维持和逆转受发育调节。该模型克服了 研究早期胚胎和胚胎细胞培养中沉默起始的技术限制。新提议 一种被称为UAS基因交换的工具，允许在数千个基因组中用突变体替代PcG蛋白。 细胞，并与敏感的分子方法，如ChIPseq兼容。第一次提出研究方向 将使用UAS基因交换来鉴定PcG蛋白和转录因子之间的相互作用， 这对于在每个潜在的Polycomb靶基因处建立或防止沉默是重要的。第二项研究 方向将探讨如何一个单一的PcG蛋白，Scm，是事后调节时间沉默启动 在区分保育细胞和其他发育环境中的作用。最后，第三个研究方向将使用高度- 一种有效的基因组工程方法来探索一些Polycomb靶基因如何稳定沉默， 有些则不然。这些不同的方向将大大促进我们对发展如何 调节Polycomb沉默。他们还将产生新的工具来研究发育中的基因表达控制。 对更广泛的研究界有价值的生物。最后，这项研究计划可能会揭示 潜在的保守机制，调节早期胚胎发育和预防人类癌症。

Project Summary Cells sharing a common genome transcribe a subset of their available genes to perform different functions. Polycomb-group (PcG) proteins contribute to cell specialization by binding and chemically modifying chromatin around lowly-transcribed genes to further reduce (“silence”) their expression. Although many PcG proteins have been identified, mystery surrounds the most interesting aspects of their function. The utility of silencing derives from its selective imposition. However, unknown mechanisms determine when silencing begins or ends during normal development. Furthermore, how PcG proteins epigenetically associate with different target genes in different cells is poorly understood. It is important to resolve these questions because silencing mistakes disrupt development and contribute to human cancers. The proposed research program uses a new model system, Drosophila nurse cell differentiation, and new genetic and genomic engineering tools to study how silencing initiation, maintenance, and reversal are developmentally regulated. The proposed model system overcomes technical limitations of studying silencing initiation in early embryos and embryonic cell cultures. A new proposed tool, termed UAS-gene swap, allows genetic substitution of PcG proteins with mutant versions in thousands of cells, and is compatible with sensitive molecular approaches like ChIPseq. The first proposed research direction will use UAS-gene swap to identify the interactions between PcG proteins and transcription factors that are important for establishing or preventing silencing at each potential Polycomb target gene. A second research direction will explore how a single PcG protein, Scm, is post-translationally regulated to time silencing initiation in differentiating nurse cells and other developmental contexts. Finally, a third research direction will use a highly- efficient genome engineering approach to explore how some Polycomb target genes are stably silenced while others are not. These diverse directions will significantly advance our understanding of how development regulates Polycomb silencing. They will also generate new tools to study gene expression control in developing organisms that will be valuable to the broader research community. Lastly, this research program may reveal potentially conserved mechanisms that regulate early embryonic development and prevent human cancers.