Regulation of chromosome segregation by SMC complexes and Top2 in S. pombe

粟酒裂殖酵母中 SMC 复合物和 Top2 对染色体分离的调节

• 批准号: 8403401
• 负责人: MATTHEW J O'CONNELL
• 金额: $ 32.59万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8403401
• 关键词: ATP phosphohydrolase; Acetyltransferase; Address; Affect; Aging; Anaphase; Aneuploidy; Biochemical; Biological; Cancer Biology; Cell Cycle; Cell Survival; Cells; Chromosome Arm; Chromosome Condensation; Chromosome Segregation; Chromosome Structures; Chromosomes; Chromosomes, Human, Pair 12; Collection; Complex; DNA; DNA Damage; DNA Repair; DNA Repair Gene; DNA biosynthesis; Data; Defect; Development; Elements; Ensure; Excision; Fission Yeast; Functional disorder; Genes; Genetic; Genome; Genotoxic Stress; Head; Homologous Gene; Human; Interphase; Interphase Chromosome; Investigation; Link; Maintenance; Malignant Neoplasms; Mediating; Mitosis; Mitotic; Mitotic Chromosome; Mutation; Peptide Hydrolases; Phenotype; Physical condensation; Prophase; Protein Family; Proteins; RNA Interference; Radiation; Regulation; Repair Complex; Role; Saccharomyces cerevisiae; Saccharomycetales; Secondary to; Shapes; Sister Chromatid; Staging; Structure; Superhelical DNA; Tail; Topoisomerase II; Work; cohesin; cohesion; condensin; dimer; homologous recombination; member; mutant; prevent; protein complex; public health relevance; repaired; scaffold; segregation; separase; spatiotemporal

DESCRIPTION (provided by applicant): Three multi-protein complexes scaffolded by members of the Structural Maintenance of Chromosomes (SMC) family of protein are key regulators of chromosome dynamics: cohesin (Smc1/3), condensin (Smc2/4) and the Smc5/6 complex. Cohesin is a key determinant of sister chromatid cohesion, where it is proposed to form a ring-shaped structure that encircles sister chromatids. Condensin is critical for mitotic chromosome condensation, at least in part by generating supercoiled DNA. However, there are also data to link cohesin to chromosome condensation, and condensin to sister chromatid cohesion. Further, both complexes are required for DNA repair, which is thought to be a secondary effect of their role in chromosome organization. Moreover, Topoisomerase II (Top2) functions in cohesion and condensation, in addition to its well-defined roles in chromosome decatenation and scaffolding of mitotic chromosomes. Thus, there is much cross talk between these complexes as cells progress through the cell cycle. The third SMC complex, Smc5/6, has been implicated in a late stage of DNA repair by homologous recombination. However, is a role in DNA repair a direct effect, or an indirect consequence of Smc5/6 function in regulating chromosome structure? Its description as a DNA repair complex is primarily historic, as it was first defined by rad18-X (now smc6-X), a radiation sensitive mutant in Schizosaccharomyces pombe. Moreover, the same collection of rad mutants includes the cohesin gene rad21. Further, Smc5/6 is essential for cell viability, but DNA repair genes are not. Thus the central question we wish to address is why is Smc5/6 essential? The data thus far suggest that Smc5/6 function is essential for accurate chromosome segregation. We have previously shown that Smc5/6 mutants show high levels of aneuploidy, and show failed mitoses following DNA damage or Top2 dysfunction. Further, Smc5/6 null mutants have a terminal phenotype of failed mitoses without extrinsic DNA damage. We propose that all three SMC complexes and Top2 functionally interact to guide chromosomes through DNA replication and mitosis. While most studies on Smc5/6 have been in the context of DNA repair, this proposal focuses specifically on the essential role of Smc5/6 in chromosome segregation, and how Smc5/6 functionally interacts with Cohesin and Topoisomerase II to ensure chromosome segregation. To this end, working in S. pombe, we pursue three specific aims that take cell biological, genetic, and biochemical approaches. First, we build on a significant body of preliminary data that links the mitotic defects of smc6 mutants following DNA damage to a defect in pre-anaphase cohesin removal. Here, we address cause versus consequence and the spatiotemporal regulation of cohesin dynamics. Secondly, we address the functional interaction between Smc5/6 and Top2, which we believe is critical for the segregation of undamaged chromosomes. Finally, we address the function of the acetyltransferase Eso1, a cohesin regulator that mechanistically links cohesin and Smc5/6 function.

描述（由申请人提供）：由染色体结构维持（SMC）蛋白家族成员构建的三种多蛋白复合物是染色体动力学的关键调节因子：粘附素（Smc 1/3）、凝聚素（Smc 2/4）和Smc 5/6复合物。凝聚素是姐妹染色单体凝聚的一个关键决定因素，它被认为形成一个包围姐妹染色单体的环形结构。凝聚素是有丝分裂染色体凝聚的关键，至少部分通过产生超螺旋DNA。然而，也有数据将粘着蛋白与染色体凝聚联系起来，并将凝聚蛋白与姐妹染色单体粘着联系起来。此外，这两种复合物都是DNA修复所必需的，这被认为是它们在染色体组织中的作用的次级效应。此外，拓扑异构酶II（Top2）的功能，凝聚和凝聚，除了其明确的作用，在染色体的脱连锁和有丝分裂染色体的支架。因此，随着细胞在细胞周期中的进展，这些复合物之间存在很多串扰。 第三个SMC复合物Smc 5/6与通过同源重组进行的DNA修复的晚期阶段有关。然而，Smc 5/6在DNA修复中的作用是直接作用，还是调节染色体结构的间接结果？它作为DNA修复复合物的描述主要是历史性的，因为它首先被定义为rad 18-X（现在的smc 6-X），一种对辐射敏感的突变体裂殖酵母。此外，相同的rad突变体集合包括粘着蛋白基因rad 21。此外，Smc 5/6对细胞活力至关重要，但DNA修复基因不是。因此，我们希望解决的中心问题是为什么Smc 5/6是必不可少的？ 到目前为止的数据表明，Smc 5/6功能是准确的染色体分离所必需的。我们以前已经表明，Smc 5/6突变体显示高水平的非整倍体，并显示失败的有丝分裂后DNA损伤或Top2功能障碍。此外，Smc 5/6无效突变体具有无外源性DNA损伤的有丝分裂失败的终末表型。我们建议，所有三个SMC复合物和Top2功能相互作用，通过DNA复制和有丝分裂指导染色体。 虽然大多数关于Smc 5/6的研究都是在DNA修复的背景下进行的，但本提案特别关注Smc 5/6在染色体分离中的重要作用，以及Smc 5/6如何在功能上与Cohesin和拓扑异构酶II相互作用以确保染色体分离。为此，在S. pombe，我们追求三个具体目标，采取细胞生物学，遗传学和生物化学方法。首先，我们建立在一个显着的机构的初步数据，连接smc 6突变体的有丝分裂缺陷后，DNA损伤的缺陷，在前期后期粘连蛋白去除。在这里，我们解决原因与后果和时空调节的凝聚力的动态。其次，我们解决了Smc 5/6和Top2之间的功能相互作用，我们认为这是分离未受损染色体的关键。最后，我们解决了乙酰转移酶Eso 1的功能，一种粘连蛋白调节剂，机械地连接粘连蛋白和Smc 5/6功能。