Protection of Centromeric Cohesion by Bub1 and Sgo1

Bub1 和 Sgo1 对着丝粒凝聚力的保护

• 批准号: 7623955
• 负责人: HONGTAO YU
• 金额: $ 35.41万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-10 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7623955
• 关键词: 45-kDa nuclear factor of activated T-cells; Address; Adopted; Affinity; Aneuploidy; Area; Binding; Binding Proteins; Biochemical; Biological Assay; C-terminal; Cells; Centromere; Chromosomal Instability; Chromosome Arm; Chromosome Cohesion; Chromosome Segregation; Chromosomes; Classification; Cleaved cell; Complex; Congenital Abnormality; Double-Stranded RNA; Down Syndrome; Electrophoretic Mobility Shift Assay; Evolution; Excision; Fission Yeast; Genetic; Genetic Materials; Goals; Hand; Hela Cells; Heterochromatin; Human; In Vitro; Kinetochores; Lead; Ligands; Ligase; Light; Maintenance; Malignant Neoplasms; Mammalian Cell; Mediating; Meiosis; Metaphase; Methods; Mitosis; Mitotic; Mitotic spindle; Molecular; Mutation; Nucleic Acid Binding; Organism; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Polynucleotide Adenylyltransferase; Precipitation; Prevention; Process; Prophase; Protein Dephosphorylation; Protein Family; Protein phosphatase; Proteins; RNA; RNA Binding; RNA Interference; RNA Interference Pathway; RNA-Binding Proteins; Recombinants; Recruitment Activity; Research; Research Personnel; Residual state; Role; Sister Chromatid; Structure; Testing; Transferase; Ubiquitination; Yeasts; cohesin; cohesion; crosslink; daughter cell; heterochromatin-specific nonhistone chromosomal protein HP-1; human PLK1 protein; in vivo; insight; interest; man; mutant; novel; oligoadenylate; premature; programs; protein complex; reconstitution; research study; separase; tumorigenesis

DESCRIPTION (provided by applicant): The genetic stability of an organism depends on the accurate partition of sister chromatids into two daughter cells during mitosis, which in turn requires the maintenance of the physical linkage (cohesion) between sister chromatids until their bipolar attachment to the mitotic spindle. Removal of cohesin (the protein complex that maintains sister chromatid cohesion) from chromosomes then leads to sister chromatid separation. In vertebrate cells, removal of cohesin occurs in two steps. At prophase, most of cohesin along the chromosome arms is removed through Polo-like kinase (Plk1)/Aurora B-dependent phosphorylation of cohesin. At metaphase, the residual centromeric pool of cohesin is cleaved by separase to allow sister chromatid separation. The long-term goal of my lab is to understand the molecular mechanism of chromosome segregation in mammalian cells. In this proposal, we will address an interesting puzzle in this area: how is the centromeric cohesin shielded from the actions of Plk1 /Aurora B in prophase? We have recently provided evidence to suggest that the spindle checkpoint kinase Bub1 targets and the Sgo1 centromeric protein and protein phosphatase 2A (PP2A) to centromeres where they counteract the phosphorylation of cohesin by Plk1 and other mitotic kinases. In Specific Aims 1 and 2, we will further delineate the mechanisms by which Bub1, Sgo1, and PP2A collaborate to protect centromeric cohesion. On the other hand, our results also point to a PP2A-independent role of Sgo1. Indeed, we have made two novel and related findings in the past year. Sgo1 directly interacts with an RNA-binding protein complex called ILF2-ILF3 (interleukin enhancer binding factors 2 and 3). Sgo1 itself binds to RNA in vitro. Experiments are planned in Aims 3 and 4 to establish the in vivo relevance of these findings. Premature loss of centromeric sister chromatid cohesion leads to chromosome missegregation and abnormal numbers of chromosomes in daughter cells (aneuploidy), which contributes to cancer formation and birth defects. The proposed research will shed light on the mechanism of chromosome segregation and may in turn lead to better understanding and prevention of chromosomal instability and aneuploidy in human cancers and birth defects, such as Down Syndrome.

描述(申请人提供)：生物体的遗传稳定性依赖于在有丝分裂过程中姐妹染色单体准确地划分为两个子细胞，这反过来又要求姐妹染色单体之间保持物理联系(凝聚力)，直到它们的两极附着在有丝分裂纺锤体上。从染色体中去除粘附素(维持姐妹染色单体凝聚力的蛋白质复合体)，然后导致姐妹染色单体分离。在脊椎动物细胞中，粘附素的去除分两步进行。在前期，大部分沿染色体臂的粘附素通过依赖于Polo-like Kinase(Plk1)/Aurora B的粘附素的磷酸化而被去除。中期，残留的着丝粒粘附素池被分离酶切割，允许姐妹染色单体分离。我的实验室的长期目标是了解哺乳动物细胞中染色体分离的分子机制。在这个提案中，我们将解决这一领域的一个有趣的谜题：着丝粒粘附素是如何在前期保护Plk1/Aurora B的作用的？我们最近提供的证据表明，纺锤体检查点激酶Bub1和Sgo1着丝粒蛋白和蛋白磷酸酶2A(PP2A)靶向着丝粒，在着丝粒上它们抵消了Plk1和其他有丝分裂酶对粘附素的磷酸化。在具体的目标1和2中，我们将进一步描述Bub1、Sgo1和PP2A合作保护着丝粒凝聚力的机制。另一方面，我们的结果也表明Sgo1的作用不依赖于PP2A。事实上，在过去的一年里，我们取得了两个新的和相关的发现。Sgo1直接与名为ILF2-ILF3(白细胞介素2和3)的RNA结合蛋白复合体相互作用。在体外，Sgo1本身可以与RNA结合。AIMS 3和AIMS 4计划进行实验，以确定这些发现的体内相关性。着丝粒姐妹染色单体凝聚力的过早丧失会导致染色体错误分离和子代细胞中染色体数量的异常(非整倍体)，从而导致癌症形成和出生缺陷。这项拟议的研究将阐明染色体分离的机制，并反过来可能导致更好地理解和预防人类癌症和出生缺陷(如唐氏综合症)中的染色体不稳定性和非整倍体。