Orienting Chromosomes on the Meiotic Spindle

项目总结 MPS1编码一种保守的激酶，对多种细胞周期相关的功能是必不可少的。的一个关键角色 MPS1的作用是促进动点与微管形成力产生联系。 减数分裂。这些连接对于染色体在减数分裂纺锤体上的正确定向至关重要， 但Mps1形成这些联系的分子机制是一个谜。减数分裂中的错误 染色体双向导致配子的染色体数目错误，称为 非整倍体，这是人类出生缺陷和智力低下的主要原因。MPS1是必需的 防止这种非整倍体，因为Mps1的缺失会导致高水平的非整倍体配子。Mps1也牵涉到 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。 Mps 1。非整倍体乳腺肿瘤细胞尤其依赖于Mps1-可能是因为 这些细胞中的高染色体数目对双向机制提出了要求。这些 结果导致了对可能作为抗肿瘤药物的抗Mps1化合物的追求。确定 Mps1在双向中的作用机制将阐明可能是 精制抗肿瘤治疗药物开发的最佳靶点。 这个项目试图确定用于形成动力产生的动粒微管的机制。 酵母减数分裂过程中的附着物，以及Mps1在这一过程中的作用。该项目有四个目标。第一个将使用 监测着丝粒和单个微管之间相互作用的成像方法，以精确定位 在Mps1突变体中有缺陷的动粒-微管连接的形成步骤。第二个目标将是 探索位于动粒微管的已知的Mps1磷酸化靶标的作用 在形成有效的动粒-微管附着体的过程中。这一目标将得到一个 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 磷酸蛋白质组。第三个目标是鉴定一组携带抑制子突变的菌株 改善Mps1-R170S突变体的染色体分离--这些抑制突变可能映射到基因 参与着动粒-微管的相互作用，他们的分析将有助于阐明Mps1是如何 调节这一过程。最终目标是确定mps1是否对有丝分裂染色体有贡献。 在减数分裂中以同样的方式促进适当的染色体分离。因为 这项提案中所研究的蛋白质在很大程度上是酵母和人类共享的，这些见解 在酵母系统中获得的数据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.