Preventing Age-Associated Oocyte Aneuploidy: Mechanisms Behind the Drosophila melanogaster Centromere Effect

预防与年龄相关的卵母细胞非整倍性：果蝇着丝粒效应背后的机制

• 批准号: 10730545
• 负责人: Nila Madassary Pazhayam
• 金额: $ 3.92万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10730545
• 关键词: Address; Affect; Age; Aneuploidy; Area; Attenuated; Biological Models; Cell Nucleus; Cell physiology; Cells; Centromere; Chromosome Segregation; Chromosome Structures; Chromosomes; Congenital chromosomal disease; Consensus; Defect; Double Strand Break Repair; Down Syndrome; Drosophila genus; Drosophila melanogaster; Ensure; Euchromatin; Event; Exclusion; Exhibits; Female; Frequencies; Genetic Crossing Over; Genetic Nondisjunction; Genetic Recombination; Global Change; Heterochromatin; Homologous Gene; Incidence; Infertility; Knowledge; Light; Mammals; Maternal Age; Measures; Meiosis; Oocytes; Organism; Participant; Pattern; Play; Process; Regulation; Research; Rest; Risk; Role; Spontaneous abortion; System; Testing; Work; X Chromosome; Y Chromosome; advanced maternal age; age related; design; experimental study; fly; genome-wide; homologous recombination; insight; novel; older women; prevent; repaired; segregation

Project Summary/Abstract During meiosis, crossing-over between homologs facilitates accurate chromosome segregation and prevents aneuploidy, which in turn forestalls miscarriages and chromosomal disorders such as Down syndrome. The regulation and placement of meiotic crossovers acts as a vital safeguard against age-associated meiotic defects and infertility, as the risk of non-disjunction (NDJ) increases with increasing maternal age. Meiotic crossovers (COs) are formed when programmed double-strand breaks (DSBs) are repaired through homologous recombination. However, only a subset of DSBs are repaired to form COs; the rest are repaired as non-crossovers (NCOs). Despite meiotic DSBs being distributed throughout the chromosome, CO placement is intricately regulated by three types of patterning phenomena. One of these, the centromere effect (CE), ensures the exclusion of COs in centromere-proximal regions and is crucial to the meiotic cell as centromere-proximal COs increase the risk of NDJ. Furthermore, increasing maternal age has been shown to weaken the CE, potentially explaining why NDJ incidence increases in older women. Although first observed in Drosophila in 1932, the mechanisms behind the CE remain unknown even today. The experiments proposed here aim to address this gap in knowledge regarding a vital cellular process that prevents mis-segregation events, especially in those with advanced maternal age. Recently, our lab showed that the CE is differentially established in the two classes of heterochromatin found at the Drosophila pericentromere. In the highly repetitive alpha heterochromatin immediately adjacent to the centromere, a complete exclusion of COs is observed, while the less repetitive beta heterochromatin adjacent to proximal euchromatin shows a distance dependent CO suppression. I will build on these results by investigating the mechanisms of how the CE is established in these two classes of pericentric heterochromatin. A prominent question regarding CE mechanisms centers around how pericentromeric heterochromatin and the centromere itself contribute to the CE. The few studies that have addressed pericentric crossing-over in the past century have attempted to establish one as more important than the other in Drosophila but failed to arrive at a consensus. Thus, pericentric heterochromatin has been considered everything from an active participant in CO reduction in adjacent intervals to nothing more than a passive spacer between euchromatin and the centromere. Through the experiments outlined in this proposal, I will ask how pericentric heterochromatin and the centromere contribute to the CE independently of each other, particularly focusing on highly repetitive alpha heterochromatin. Investigating the role of alpha heterochromatin as separate from that of pericentric heterochromatin as a whole in manifesting the CE is a novel area of research within the broader question of how the CE is established. In summary, this proposal will increase our understanding of the mechanisms that safeguard against age- related aneuploidy and infertility through shedding light on meiotic crossover patterning.

项目摘要/摘要 在减数分裂期间，同源物之间的跨越促进了准确的染色体分离并防止 非整倍性又阻止了流产和染色体疾病，例如唐氏综合症。这 减数分裂跨界的调节和放置是针对年龄相关的减数分裂的重要保障 由于非分离风险（NDJ）随着产妇年龄的增长而增加，缺陷和不育。 当编程双链断裂（DSB）通过修复时，形成减数分裂跨界（cos） 同源重组。但是，仅修复DSB的子集以形成COS。其余的修复为 非交叉（NCO）。尽管减数分裂DSB在整个染色体中分布，但CO放置是 由三种类型的图案现象精心调节。其中之一，丝粒效应（CE）确保 COS在Centromere-Proximal区域中的排除，对于减数分裂细胞至关重要 cos增加了NDJ的风险。此外，已经显示出孕妇年龄的增长会削弱CE， 有可能解释为什么NDJ发生率会增加老年妇女。虽然在果蝇中首先观察到 1932年，即使在今天，CE背后的机制仍然未知。这里提出的实验旨在 在有关阻止错误隔离事件的重要细胞过程的知识中解决这一差距， 尤其是在母亲年龄的人。最近，我们的实验室表明CE是差异的 建立在果蝇果粒粒粒粒粒粒粒蛋白酶的两类异染色质中。在高度重复的 α异染色质紧邻丝粒，观察到COS的完全排除，而 邻近近端白染色质相邻的重复性β异染色质较少，显示了距离依赖性CO 抑制。我将通过调查如何建立CE的机制来建立这些结果 在这两个类别的上述异染色质中。关于CE机制的一个突出的问题 围绕质质粒异染色质和丝粒本身对CE的贡献。少数 过去一个世纪已经解决了上十大穿越的研究试图将一项建立为 比果蝇中的另一个更重要，但没有达成共识。因此，上十大异染色质 已经被认为是从积极的参与者减少相邻时间间隔的一切 比斑塑素和丝粒之间的被动间隔者。通过此概述的实验 提案，我会问上美上性异染色质和丝粒如何为CE做出贡献 彼此独立，特别是专注于高度重复的α异染色质。 研究α异染色质的作用是与周围异染色质分开的作用 在表现出CE的过程中，是在CE建立方式的更广泛问题中的一个新颖研究领域。在 总而言之，该提案将提高我们对保护年龄的机制的理解。 通过阐明减数分裂跨界图案，相关的非整倍性和不育。