The Role of Telomeres in Chromosome Pairing in Meiosis

端粒在减数分裂染色体配对中的作用

• 批准号: 9808000
• 负责人: Michael Dresser
• 金额: $ 34.5万
• 依托单位: Oklahoma Medical Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2002-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9808000&HistoricalAwards=false
• 关键词: Role; Telomeres; Chromosome; Pairing; Meiosis

The essential function of meiosis is to haploidize the genome, a process which depends on chromosome pairing in meiotic prophase. A long history of cytological and genetic studies have suggested a role for telomere-mediated movements in meiotic chromosome pairing but there has been little experimental evidence for the role and few insights into the molecular mechanisms involved. The meiotic telomere protein Ndj1p is required for normal telomere organization and for normal meiotic chromosome behavior in S. cerevisiae, its absence causing delays-in axial element formation, synapsis and entry into the first meiotic division-and defects in chromosome recombination and segregation. Thus, Ndj1p may function at telomeres to facilitate chromosome pairing, perhaps at the early meiotic stage of bouquet formation. The hypothesis that Ndj1p fosters telomere-mediated homologous pairing by moving chromosomes together and/or by stabilizing pairing interactions will be tested by examining telomere positions in fixed, embedded material using a quantitative immunocytological approach and also by analyzing the movements of green fluorescent protein-tagged chromosomes in vivo. In addition, axial element formation, synapsis, and recombination will be compared in wild-type and NDJj1 deletion cells using a quantitative immunocytological approach, with particular attention to the kinetics of these events with respect to subnuclear locations. The hypothesis that NdJ1 is required for subtelomeric pairing associations that persist in the absence of recombination will be tested by assessing pairing near the telomeres using an in situ hybridization-based assay. The hypothesis that NDJ1 influences recombination by affecting DNA double-strand break formation will be assessed by comparing the frequency and positions of double-strand breaks and the kinetics of break formation in different wild-type backgrounds and in mutant backgrounds where breaks persist and are stable. Finally, essential genes which are candidates for interaction with NDJ1 will be evaluated for meiosis-and NDJ1-specific function using a plasmid-shuffle approach to identify separation-of-function and /or conditional mutations. The questions addressed by these experiments are of general significance for their importance in understanding mechanisms of meiotic chromosome pairing and of telomere-mediated positioning of chromosomes in the nucleus, which can influence any process sensitive to nuclear architecture, and thus affect the fidelity of chromosome segregation.

减数分裂的基本功能是使基因组单倍化，这一过程依赖于减数分裂前期的染色体配对。 长期的细胞学和遗传学研究表明，端粒介导的运动在减数分裂染色体配对中的作用，但很少有实验证据的作用，很少有见解的分子机制。 减数分裂端粒蛋白Ndj 1 p是S.酿酒酵母，它的缺乏造成延迟轴元件的形成，联会和进入第一次减数分裂和缺陷染色体重组和分离。 因此，Ndj 1 p可能在端粒的功能，以促进染色体配对，也许在早期减数分裂阶段的花束形成。 Ndj 1 p通过移动染色体和/或稳定配对相互作用促进端粒介导的同源配对的假设将通过使用定量免疫细胞学方法检查固定的包埋材料中的端粒位置以及通过分析体内绿色荧光蛋白标记的染色体的运动来测试。 此外，轴向元件的形成，突触和重组将在野生型和NDJj 1缺失细胞使用定量免疫细胞学方法进行比较，特别注意这些事件的动力学相对于亚核位置。 假设NdJ 1是所需的亚端粒配对协会，坚持在重组的情况下，将通过评估配对附近的端粒使用原位杂交为基础的测定进行测试。 NDJ 1通过影响DNA双链断裂形成来影响重组的假设将通过比较不同野生型背景和断裂持续且稳定的突变体背景中双链断裂的频率和位置以及断裂形成的动力学来评估。 最后，将使用质粒改组方法评估作为与NDJ 1相互作用的候选者的必需基因的减数分裂和NDJ 1特异性功能，以鉴定功能分离和/或条件突变。 这些实验所解决的问题具有普遍意义，因为它们在理解减数分裂染色体配对和端粒介导的染色体在细胞核中的定位机制中具有重要意义，这可以影响对核结构敏感的任何过程，从而影响染色体分离的保真度。