Preventing Aneuploidy in Aging Oocytes: Investigating the effects and mechanisms of cohesion enrichment in Drosophila melanogaster.

预防老化卵母细胞的非整倍性：研究果蝇内聚力富集的效果和机制。

• 批准号: 9190590
• 负责人: Talia Lee Hatkevich
• 金额: $ 3.15万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9190590
• 关键词: Accounting; Address; Advanced Development; Affect; Age; Aging; Alleles; Aneuploidy; Biological Process; Candidate Disease Gene; Cell division; Cells; Centromere; Chromosome Arm; Chromosomes; Complex; Deterioration; Diploid Cells; Diploidy; Disease; Down Syndrome; Drosophila genus; Drosophila melanogaster; Event; Failure; Genes; Genetic Nondisjunction; Genetic Recombination; Germ Cells; Goals; Haploidy; Hereditary Disease; Heterochromatin; Immunofluorescence Immunologic; Immunoprecipitation; Incidence; Kinetochores; Knowledge; Lead; MCM5 gene; Maintenance; Mass Spectrum Analysis; Maternal Age; Measures; Meiosis; Modeling; Mutation; Oocytes; Optic Chiasm; Ovulation; Prevention; Prevention strategy; Process; Proteins; Proteomics; Protocols documentation; Recruitment Activity; Research; Role; Scheme; Sister Chromatid; Spontaneous abortion; Testing; Therapeutic; Time; XCL1 gene; abstracting; advanced maternal age; age effect; age related; aged; arm; clinically relevant; cohesin; cohesion; design; fly; in utero; insight; knock-down; mutant; novel; novel strategies; prevent; segregation

Abstract The overall goal for meiosis I is to successfully segregate homologous chromosomes into two diploid cells. Failure to do so results in aneuploidy, which is the leading cause of genetic disorders, such as Trisomy 21, and miscarriages due to spontaneous abortions. Incidences of chromosomal nondisjunction (NDJ) increase exponentially as an oocyte ages, a phenomenon termed the maternal-age effect. Age-related chromosomal NDJ is hypothesized to be caused by the inability of an oocyte to maintain a chiasma, the physical manifestation of a crossover (CO) between homologous chromosomes, until ovulation. Sister chromatid cohesion (SCC) is vital for maintenance of chiasmata; thus, SCC deterioration is thought to contribute to age- related NDJ. Studies have shown that an overall reduction of SCC causes age-related NDJ, but it is currently unknown whether the loss of SCC around the centromere has a greater impact on age-related NDJ than loss of SCC at the chromosome arms. Because arm SCC and centromere SCC have distinct roles in meiosis, understanding the role of each may provide insight into the mechanism underlying age-related NDJ. In Drosophila, loading of arm cohesion proteins is facilitated by Nipped-B, but the process governing centromere cohesin loading remains largely unknown. Recently, I characterized a separation-of-function allele, mcm5A7, and demonstrated that the mcm5A7 mutation does not affect the replication role of MCM5; instead, this mutation increases meiotic NDJ presumably by reducing loading of the cohesion protein SMC1 at the centromere. This result suggests that MCM5 is involved in recruiting or establishing SMC1 at the centromere in meiotic cells, a role for MCM5 that has not been previously described. As described in this proposal, I will test the importance of centromeric SCC versus arm SCC in age-related NDJ in Drosophila by utilizing mcm5A7 to disrupt centromeric SCC and a mutation in Nipped-B to disrupt arm SCC. I will then employ an oocyte aging protocol to measure the incidence of age-related NDJ in both mutants. Further, through proteomic studies and immunofluorescence, I propose to investigate the mechanism by which MCM5 functions to facilitate SMC1 at the centromere in meiotic cells. Overall, the lack of knowledge in the field regarding the importance of centromeric SCC and arm SCC in age-related NDJ, as well as the role of MCM5 in establishing centromeric cohesion, prevents progression of therapeutics and basic understanding in how to prevent age-related aneuploidy. The proposed research will help fill this fundamental gap and advance the development of prevention strategies.

抽象的 减数分裂 I 的总体目标是成功地将同源染色体分离成两个二倍体细胞。 如果不这样做，就会导致非整倍体，这是遗传性疾病（如 21 三体症）的主要原因 自然流产导致的流产。染色体不分离 (NDJ) 的发生率增加 随着卵母细胞年龄的增长，这种现象被称为母体年龄效应。与年龄相关的染色体 NDJ 被假设是由卵母细胞无法维持交叉（物理交叉）引起的。 同源染色体之间交叉（CO）的表现，直到排卵。姐妹染色单体 内聚力（SCC）对于维持交叉至关重要；因此，SCC 恶化被认为是导致年龄增长的原因之一。 相关NDJ。研究表明，SCC 的总体减少会导致与年龄相关的 NDJ，但目前 未知着丝粒周围 SCC 的丢失是否比丢失对年龄相关的 NDJ 具有更大的影响 染色体臂上的 SCC。由于臂 SCC 和着丝粒 SCC 在减数分裂中具有不同的作用， 了解每个因素的作用可以帮助我们深入了解与年龄相关的 NDJ 的潜在机制。在 果蝇，Nipped-B 促进了臂粘连蛋白的装载，但控制着丝粒的过程 粘连蛋白负载仍然很大程度上未知。最近，我鉴定了一个功能分离等位基因 mcm5A7， 并证明mcm5A7突变不影响MCM5的复制作用；相反，这个突变 推测是通过减少着丝粒处的粘连蛋白 SMC1 的负载来增加减数分裂 NDJ。这 结果表明，MCM5 参与在减数分裂细胞的着丝粒处募集或建立 SMC1，这是一种 MCM5 的作用以前没有描述过。正如这个提案中所描述的，我将测试重要性 利用 mcm5A7 破坏果蝇年龄相关 NDJ 中着丝粒 SCC 与臂 SCC 的差异 着丝粒 SCC 和 Nipped-B 突变破坏臂 SCC。然后我将采用卵母细胞老化方案 测量两个突变体中与年龄相关的 NDJ 的发生率。此外，通过蛋白质组学研究和 免疫荧光，我建议研究 MCM5 促进 SMC1 发挥作用的机制 减数分裂细胞中的着丝粒。总体而言，该领域缺乏对重要性的认识。 年龄相关NDJ中的着丝粒SCC和臂SCC，以及MCM5在建立着丝粒中的作用 凝聚力，防止治疗的进展以及如何预防与年龄相关的基本了解 非整倍体。拟议的研究将有助于填补这一根本空白并推动发展 预防策略。