Orienting Chromosomes on the Meiotic Spindle

项目概要 MPS1 编码一种保守激酶，对于多种细胞周期相关功能至关重要。其中一个关键角色是 MPs1 促进着丝粒与微管形成力产生关联 减数分裂。这些连接对于染色体在减数分裂纺锤体上正确定位至关重要， 但 Mps1 形成这些关联的分子机制仍然是个谜。减数分裂错误 染色体双向性导致配子的染色体数量错误，称为 非整倍体，在人类中是出生缺陷和智力低下的主要原因。 MPS1 是必要的 防止这种非整倍体，因为 Mps1 的丢失会导致高水平的非整倍体配子。 MPS1也受到牵连 人类癌症。许多人类癌症是非整倍体，具有非常高的染色体数量，并且过度表达 mps1。非整倍体乳腺肿瘤细胞尤其依赖于 Mps1——大概是因为 这些细胞中的高染色体数量对双向机制提出了要求。这些 研究结果促使人们寻找可能作为抗肿瘤药物的抗 Mps1 化合物。确定 Mps1 双向作用机制将阐明特定的 Mps1 蛋白相互作用，这可能是 开发精细抗肿瘤疗法的最佳目标。 该项目旨在确定用于形成力产生着丝粒微管的机制 酵母减数分裂中的附着物，以及 Mps1 在该过程中的作用。该项目有四个目标。第一个将使用 成像方法监测着丝粒和单个微管之间的相互作用，以查明 开发动粒-微管附着的步骤在 mps1 突变体中是有缺陷的。第二个目标将 探索位于动粒微管的已知 Mps1 磷酸化靶标的作用 界面，形成有效的动粒-微管附件。这一目标将得到以下支持： 与研究人员合作，通过绘制 Mps1 的图谱来发现 Mps1 的新磷酸化靶点 磷酸化蛋白质组。第三个目标是鉴定携带抑制突变的菌株集合，这些突变 改善 mps1-R170S 突变体中的染色体分离 - 这些抑制突变可能映射到基因 参与动粒-微管相互作用的细胞，它们的分析将揭示 Mps1 的作用机制 规范这个过程。最终目标是确定 Mps1 是否有助于染色体有丝分裂 分离的方式与它促进减数分裂中适当的染色体分离的方式相同。因为 该提案中所检查的蛋白质大部分是酵母和人类之间共享的，这些见解 在酵母系统中获得的结果可能对更好地理解非整倍体的起源具有重要意义 以及人类癌症的治疗。

PROJECT SUMMARY MPS1 encodes a conserved kinase that is essential for multiple cell cycle related functions. One critical role for Mps1 is to promote the formation of force-generating associations of kinetochores with microtubules in meiosis. These connections are critical for chromosomes to become properly oriented on the meiotic spindle, but the molecular mechanisms by which Mps1 forms these associations is a mystery. Errors in meiotic chromosome bi-orientation lead to gametes with the wrong number of chromosomes, referred to as aneuploidy, which in humans is the leading cause of birth defects and mental retardation. Mps1 is necessary to prevent this aneuploidy, as loss of Mps1 leads to high levels of aneuploid gametes. Mps1 is also implicated in human cancer. Many human cancers are aneuploid, with very high chromosome numbers, and over-express Mps1. Aneuploid breast tumor cells are especially dependent upon Mps1 – presumably because of the demands placed upon the bi-orientation machinery by the high chromosome numbers in these cells. These results have led to the pursuit of anti-Mps1 compounds that might act as anti-tumor drugs. Determining the mechanism-of-action of Mps1 in bi-orientation would clarify the specific Mps1 protein interactions that might be the best targets for the development of refined anti-tumor therapeutics. This project seeks determine the mechanisms used to form force-generating kinetochore-microtubule attachments in yeast meiosis, and the role of Mps1 in that process. The project has four Aims. The first will use imaging approaches to monitor the interactions between a centromere and a single microtubule, to pinpoint the step in developing kinetochore-microtubule attachments that is defective in mps1 mutants. A second Aim will explore the roles of known phosphorylation targets of Mps1 that reside at the kinetochore-microtubule interface, in the formation of productive kinetochore-microtubule attachments. This aim will be supported by a collaboration with investigators who will uncover new phosphorylation targets of Mps1 by mapping the Mps1 phospho-proteome. A third Aim is to characterize a collection of strains that carry suppressor mutations that improve chromosome segregation in mps1-R170S mutants – these suppressor mutations likely map to genes that are involved in kinetochore-microtubule interactions and their analysis will shed light on how Mps1 is regulating this process. The final objective is to determine whether Mps1 contributes to mitotic chromosome segregation in the same way that it promotes proper chromosome segregation in meiosis. Because the proteins being examined in this proposal are for the most part shared between yeast and humans, the insights gained in the yeast system could have important implications for better understanding the origins aneuploidy and treatment of cancer in humans.