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: 8598902
• 负责人: MATTHEW J O'CONNELL
• 金额: $ 33.77万
• 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 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8598902
• 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）家族的成员脚手架的三种多蛋白络合物是染色体动力学的关键调节剂：粘粘蛋白（SMC1/3），Condensin（SMC2/4）和SMC5/6复合物。粘着蛋白是姐妹染色单体内聚力的关键决定因素，在其中，它建议形成环绕姐妹染色单体的环形结构。冷凝蛋白至少对有丝分裂染色体凝结至关重要，至少部分通过产生超螺旋DNA。但是，还有一些数据可以将粘着素与染色体凝结联系起来，并将其与姐妹染色单体凝聚联系起来。此外，DNA修复所必需的两个复合物，这被认为是其在染色体组织中作用的次要作用。此外，除了其在染色体衰减和有丝分裂染色体的脚手架中，拓扑异构酶II（TOP2）在凝聚力和凝结中的功能。因此，随着细胞在整个细胞周期的发展，这些复合物之间存在很多串扰。 第三个SMC复合物SMC5/6与同源重组有关DNA修复的后期。但是，在DNA修复中的作用是直接效应，还是SMC5/6功能在调节染色体结构中的间接结果？它作为DNA修复复合物的描述主要是历史性的，因为它最初是由rad18-X（现为SMC6-X）定义的，这是schizosacachomyces pombe中的辐射敏感突变体。此外，同一集合的RAD突变体包括粘蛋白基因RAD21。此外，SMC5/6对于细胞活力至关重要，但DNA修复基因却不是必不可少的。因此，我们希望解决的主要问题是为什么SMC5/6必不可少？ 到目前为止，数据表明SMC5/6功能对于准确的染色体分离至关重要。我们先前已经表明，SMC5/6突变体显示出高水平的非整倍性，并且在DNA损伤或TOP2功能障碍后显示出丝线失败。此外，SMC5/6空突变体具有末端表型的失败有丝分裂，而没有外部DNA损伤。我们建议所有三种SMC复合物和TOP2在功能上相互作用，以通过DNA复制和有丝分裂引导染色体。 虽然大多数关于SMC5/6的研究都在DNA修复的背景下，但该提案专门介绍了SMC5/6在染色体分离中的基本作用，SMC5/6在功能上与粘蛋白和拓扑异构酶II的功能相互作用，以确保染色体分离。为此，我们在S. Pombe工作，我们追求三个采用细胞生物学，遗传和生化方法的特定目标。首先，我们建立在大量的初步数据的基础上，该数据将DNA损伤后SMC6突变体的有丝分裂缺陷与消失前粘着素的缺陷联系起来。在这里，我们解决了粘着蛋白动力学的原因与后果与后果调节。其次，我们解决了SMC5/6和TOP2之间的功能相互作用，我们认为这对于隔离未损坏的染色体至关重要。最后，我们解决了乙酰基转移酶ESO1的功能，乙酰转移酶ESO1是一种粘着蛋白调节剂，可以将粘蛋白和SMC5/6功能联系起来。