A novel animal model approach to investigate neocentromere formation and inactiva

项目摘要 着丝粒是存在于所有染色体上的基本顺式元件，其指导动粒组装， 在有丝分裂和减数分裂中染色体分离。在人类中，只有一个着丝粒的存在是一个 防止染色体丢失或重排的必要先决条件。新着丝粒动物很少见， 在非典型（异位）位置组装并与发育有关的着丝粒 异常、流产和癌症进展。有害的潜力和相对罕见的 新着丝粒表明它们的形成可能在正常细胞中被阻止，这就引出了一个问题， 这些机制是否可以在疾病中改变。很少有机械信息存在关于如何 新着丝粒的形成和什么机制防止这种情况的发生;知识差距，这 提案旨在填补。阻碍阐明这些机制的一个主要障碍是， 缺乏允许在复杂生物体中诱导新着丝粒的测定。该研究计划将 分析新形成的neocentromeres，和他们的繁殖，从表观遗传，结构和功能 的观点，并将确定机制，抑制新着丝粒的完整染色体，使用 新的，可诱导的果蝇新着丝粒系统。拟议的工作将确定：1） 新着丝粒形成时发生的染色质结构; 2）组蛋白伴侣对此的贡献 过程; 3）新着丝粒形成对基因组稳定性和生物体活力的影响;以及4）新着丝粒形成对基因组稳定性和生物体活力的影响。 机制和分子介导的新着丝粒失活。我们希望这些研究将有助于 用于以新着丝粒的存在为特征的疾病的诊断工具或疗法的进展， 用于人类基因靶向递送的合成染色体的开发。

Project Summary Centromeres are essential cis elements present on all chromosomes that direct kinetochore assembly and chromosome segregation in mitosis and meiosis. In humans, the presence of exactly one centromere is an essential prerequisite to prevent chromosomal loss or rearrangement. Neocentromeres are rare, functional centromeres that assemble at atypical (ectopic) locations and that are implicated in developmental abnormalities, miscarriages and cancer progression. The deleterious potential and relative infrequency of neocentromeres suggest that their formation may be prevented in normal cells, which begs the question of whether such mechanisms could be altered in disease. Very little mechanistic information exists about how neocentromeres form and what mechanisms protect against such an occurrence; knowledge gaps that this proposal aims to fill. A major obstacle that has prevented the elucidation of these mechanisms has been the lack of assays that allow the induction of neocentromeres in a complex organism. The research proposed will analyze newly formed neocentromeres, and their propagation, from an epigenetic, structural and functional perspective and will identify the mechanisms that suppress neocentromeres on intact chromosomes, using a novel, inducible neocentromere system in Drosophila. The proposed work will determine: 1) the changes in chromatin structure that occur upon neocentromere formation; 2) the contribution of histone chaperones to this process; 3) the effects of neocentromere formation on genome stability and organism viability and 4) the mechanism and molecules mediating neocentromere inactivation. We hope that these studies will contribute to advances in diagnostic tools or therapies for diseases characterized by the presence of neocentromeres and to the development of synthetic chromosomes for human gene target delivery.