A novel animal model approach to investigate neocentromere formation and inactiva

描述（由申请人提供）：着丝粒是所有染色体上存在的基本顺式元件，在有丝分裂和减数分裂中指导动粒组装和染色体分离。在人类中，恰好一个着丝粒的存在是防止染色体丢失或重排的必要先决条件。新着丝粒是罕见的功能性着丝粒，其在非典型（异位）位置组装，并且与发育异常、流产和癌症进展有关。新着丝粒的有害潜力和相对罕见表明，它们的形成可以在正常细胞中被阻止，这就引出了这样的机制是否可以在疾病中改变的问题。关于新着丝粒如何形成以及有哪些机制可以防止这种情况发生的机械信息很少;本提案旨在填补知识空白。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。这项研究将从表观遗传、结构和功能的角度分析新形成的新着丝粒及其繁殖，并将使用果蝇中一种新型的诱导性新着丝粒系统来确定抑制完整染色体上新着丝粒的机制。拟开展的工作将确定：1）新着丝粒形成时发生的染色质结构变化; 2）组蛋白伴侣对这一过程的贡献; 3）新着丝粒形成对基因组稳定性和生物体活力的影响; 4）介导新着丝粒失活的机制和分子。我们希望这些研究将有助于诊断工具或治疗以新着丝粒存在为特征的疾病的进展，并有助于开发用于人类基因靶向递送的合成染色体。

DESCRIPTION (provided by applicant): 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.