Heterochromatin formation in X-inactivation

描述(由申请人提供)：在着丝粒周围异染色质形成和X失活领域的最新发展揭示了这两个过程之间的一些惊人的相似之处。哺乳动物女性胚胎干细胞中的X失活可以被认为是发育调节的兼性异染色质形成过程。该项目的长期目标是有助于理解Xist RNA启动的对非活性X染色体的选择性抑制。具体的目的是：1)鉴定和研究与X-特异性组蛋白修饰相互作用的效应蛋白；2)阐明Xist RNA招募Ezh2和可能的其他HMT参与X失活的机制。已经提出了一系列生化、生物物理、免疫细胞学和细胞生物学的方法，首先检测CBX蛋白与组蛋白修饰和RNA的可能相互作用，然后扩展到更多的潜在候选者，最终对X-失活过程中更多的关键成员进行无偏见的筛选。这项研究不仅将加深我们对异染色质作为一种广泛使用的表观遗传调节因子所起作用的理解，而且还将为早期胚胎发育和胚胎干细胞分化的一个重要方面提供见解。

DESCRIPTION (provided by applicant): Recent development in the field of pericentromeric heterochromatin formation and X-inactivation revealed some striking similarities between the two processes. X-inactivation in mammalian female embryonic stem cells can be regarded a developmentally regulated facultative heterochromatin formation process. The long- range goal of this project is to contribute to the understanding of Xist RNA initiated selective repression of inactive X chromosome. Specific aims are to: 1) identify and study the effector proteins that interact with Xi- specific histone modifications, and 2) elucidate the mechanism by which Xist RNA recruit Ezh2 and possible other HMTs to participate in X inactivation. A series of biochemical, biophysical, immunocytological, and cell biological approaches have been proposed, first to examine Cbx proteins for possible interactions with histone modifications and RNAs, then to expand to more potential candidates and eventually perform unbiased screen for more key players in X-inactivation process. The proposed research will not only further our understanding of roles played by heterochromatin as a widely-used epigenetic regulator, but also provide insights into an important aspect of early embryonic development and embryonic stem cell differentiation.