A novel animal model approach to investigate neocentromere formation and inactiva

描述(申请人提供)：着丝粒是存在于所有染色体上的基本顺式元件，在有丝分裂和减数分裂中指导着丝粒组装和染色体分离。在人类中，只有一个着丝粒的存在是防止染色体丢失或重排的基本前提。新着丝粒是一种罕见的功能性着丝粒，它聚集在非典型(异位)位置，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的频率表明，它们在正常细胞中的形成可能是被阻止的，这就引出了这样一个问题：在疾病中，这种机制是否可以改变。关于新温点是如何形成的，以及什么机制可以防止这种情况的发生，几乎没有机械性的信息；这项提议旨在填补的知识空白。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八粒的分析。这项研究将从表观遗传学、结构和功能的角度分析新形成的新着丝粒及其繁殖，并将使用一种新的、可诱导的新着丝粒系统在果蝇中识别抑制完整染色体上的新着丝粒的机制。这项拟议的工作将确定：1)新着丝粒形成过程中染色质结构的变化；2)组蛋白伴侣在这一过程中的作用；3)新着丝粒形成对基因组稳定性和生物体活力的影响；4)新着丝粒失活的机制和分子。我们希望这些研究将有助于以新着丝粒存在为特征的疾病的诊断工具或治疗方法的进步，并有助于开发用于人类基因靶向传递的合成染色体。

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.