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的总体目标是成功将同源染色体分离为两个二倍体细胞。 不这样做会导致非整倍性，这是遗传疾病的主要原因，例如21和 由于自发流产而导致的流产。染色体非分离（NDJ）的发生率增加 作为卵母细胞年龄的指数，这种现象称为母亲年龄效应。与年龄有关的染色体 假设NDJ是由于卵母细胞无法维持chiasma，物理的原因而引起的 同源染色体之间的交叉（CO）表现出来，直到排卵。姐妹染色质酸 凝聚力（SCC）对于维持Chiasmata至关重要；因此，据认为SCC恶化会导致年龄 相关的NDJ。研究表明，SCC的总体降低会导致与年龄相关的NDJ，但目前是 尚不清楚Centromere周围的SCC损失对与年龄相关的NDJ有更大的影响 SCC在染色体臂上。由于ARM SCC和Centromere SCC在减数分裂中具有不同的作用，因此 了解每个人的作用可能会洞悉与年龄相关的NDJ的基本机制。在 果蝇，手臂内聚力蛋白的负载由nipped-b促进，但处理中心的过程 粘着蛋白负荷在很大程度上未知。最近，我表征了功能分离等位基因，MCM5A7， 并证明MCM5A7突变不影响MCM5的复制作用。相反，这种突变 大概是通过减少Centromere的内聚力蛋白SMC1的负载来增加减数分裂NDJ。这 结果表明，MCM5参与减数分裂细胞中的丝粒募集或建立SMC1，A MCM5的角色先前尚未描述。如本提案中所述，我将测试重要性 果蝇中与年龄相关的NDJ中的Cenctromeric SCC与ARM SCC通过使用MCM5A7的破坏 Centromeric SCC和Nipped-B中的突变，以破坏ARM SCC。然后，我将使用卵母细胞老化协议 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 AT的机制 减数分裂细胞中的丝粒。总体而言，该领域缺乏有关重要性的知识 与年龄相关的NDJ中的Centromeric SCC和ARM SCC，以及MCM5在建立CencerRomeric中的作用 凝聚力，防止治疗疗法的进展以及如何预防与年龄相关的基本理解 非整倍性。拟议的研究将有助于填补这一基本差距，并促进 预防策略。