Mps1 and regulation of kinetochore-microtubule interactions in meiosis

在细胞内准确移动染色体的能力对有机体的生存至关重要。成功的细胞分裂取决于首先复制每条染色体中包含的遗传物质，然后积极地将染色体分割成两个精确的集合，最后分割细胞，使每个子细胞只包含两个染色体集合中的一个。有性繁殖生物有两种类型的细胞分裂，有丝分裂和减数分裂。有丝分裂产生大多数细胞类型，而减数分裂产生配子。在这两种类型的分裂中，染色体的移动都是通过将被称为微管的电缆连接到染色体上被称为着丝粒的连接处，然后缩短电缆将染色体拉到它们的目的地来实现的。这些电缆从原子核的相反两侧生长为两个阵列。为了连接到电缆末端，复制的染色体对必须首先移动到细胞核的中间。有丝分裂和减数分裂这两种类型的染色体分离事件有几个相似之处，但它们几个不同之处的分子基础尚不清楚。Mps1是一种保守的蛋白质，在有丝分裂和减数分裂中都是必不可少的，但具有减数分裂特有的功能，这可能揭示了这些过程中的根本差异。本项目旨在区分Mps1在有丝分裂和减数分裂中的不同作用和分子机制。Mps1定位于动点，可能通过激活其他蛋白质来控制染色体的移动，使染色体能够移动到微管阵列的中间，连接到微管末端，并缩短微管来移动染色体。该项目将产生更广泛的影响，为俄克拉荷马州的高中生和大学生提供机会，进行独立的假设驱动的基础研究项目。来自当地城市高中的学生将有机会进行为期一年的研究项目，在这些项目中，他们将研究可能与Mps1相互作用的候选蛋白质，以控制染色体运动。每年夏天，在一个寄宿研究项目中，来自俄克拉何马州农村地区的两名学生将能够参加为期八周的研究实习，调查Mps1控制染色体运动的机制。这个项目的共同目标是促进对复杂细胞过程的理解，并向学生介绍基础研究的文化。有丝分裂或减数分裂纺锤体上染色体的准确分离取决于一系列连续的步骤。首先，染色体向纺锤体中部移动，这一步骤被称为染色体聚集。第二，形成正确的动粒-微管(k-MT)附着体。然后动粒微管解聚，促进染色体向极迁移。但触发这些事件的信号是什么？Mps1编码一种保守的必需激酶，已被证明参与了几种生物有丝分裂和减数分裂中细胞周期进程和染色体分离的几个关键步骤。来自分裂酵母和哺乳动物的实验表明，Mps1促进了染色体滑动的假设，这是一个在早中期将染色体移动到纺锤体中间区的过程。此外，在芽殖酵母减数分裂中，Mps1是形成稳定的k-MT附着物所必需的，然后需要触发MT解聚以促进向极的染色体移动。这个项目测试了一种假设，即Mps1是芽期酵母减数分裂中染色体分离中多个顺序事件的关键调节因子。这个项目将阐明驱动有秩序的减数分裂行为的新机制。这个项目有三个目标。第一个是确定Mps1的几个功能在减数分裂中是否保守，包括依赖MT的染色体从两极到纺锤体中间区的滑动，称为染色体滑动。这一目标还将检验Mps1对于调控这一过程是必要的假设，并确定其调控目标。第二个目标是确定Mps1的几个蛋白磷酸化靶点在双向过程中的三个连续步骤中所起的作用：在早期中期向纺锤体中间区聚集，将动粒附着到MTS，以及动粒MTS解聚以触发向极的染色体运动。第三个目标是利用Mps1(Mps1-R170S)的功能分离等位基因，它表现出非常轻微的有丝分裂缺陷，但严重的减数分裂缺陷。在Mps1-R170S突变体中分离到了改善减数分裂染色体分离的抑制突变。将对这些突变体进行评估，以确定减数分裂中对Mps1功能特别敏感的途径。这些实验将一起阐明Mps1如何在多个步骤帮助控制和指导染色体，从聚集到微管附着，再到减数分裂中纺锤体上的双向。该项目由分子和细胞生物科学部门的细胞动力学和功能集群以及已建立的刺激竞争研究计划(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The ability to accurately move chromosomes within the cell is crucial for an organism’s survival. Successful cell division depends upon first duplicating the genetic material contained within each chromosome, then actively partitioning the chromosomes into two exact sets, and finally dividing the cell so each daughter cell contains just one of the two chromosome sets. Sexually reproducing organisms have two types of cell division, mitosis and meiosis. Mitosis produces most cell types, whereas meiosis produces gametes. In both types of division, chromosome movement is achieved by attaching cables, called microtubules, to a connecting site on the chromosomes, called the kinetochore, and then shortening the cables to pull the chromosomes to their destinations. The cables grow as two arrays from opposite sides of the nucleus. To become attached to a cable end, the duplicated chromosome pair must first move towards the middle of the nucleus. The two types of chromosome segregating events, mitosis and meiosis, share several similarities, but the molecular basis for several of their differences are not known. Mps1 is a conserved protein that is essential in both mitosis and meiosis, but with meiosis-specific functions that may reveal fundamental differences in these processes. This project aims to distinguish the different roles and molecular mechanisms of Mps1 in mitosis and meiosis. Mps1 localizes to kinetochores and may control chromosome movements by activating other proteins to enable chromosome movements to the middle of the microtubule arrays, connections to microtubule ends and shortening of microtubules to move the chromosomes. This Project will have a Broader Impact by providing an opportunity for Oklahoma high school and college students to perform independent hypothesis-driven basic research projects. Students from local urban high schools will have the opportunity to perform year-long research projects in which they will investigate candidate proteins that might interact with Mps1 to control chromosome movements. Each summer in a residential research program, two students from rural areas of Oklahoma will be able to participate in an eight-week research internship investigating the mechanisms by which Mps1 controls chromosome movement. This project has the combined goal of advancing understanding of a sophisticated cellular process and introducing students to a culture of basic research.Accurate segregation of chromosomes on the mitotic or meiotic spindle depends upon a series of sequential steps. First chromosomes move towards the spindle mid-zone, a step called chromosome congression. Second correct kinetochore-microtubule (k-MT) attachments are formed. Then kinetochore microtubules depolymerize to promote poleward chromosome migration. But what are the signals that trigger these events? MPS1 encodes a conserved essential kinase that has been shown be involved in several key steps in cell cycle progression and chromosome segregation in both mitosis and meiosis in several organisms. Experiments from fission yeast and mammals suggest the hypothesis that Mps1 promotes chromosome gliding, a process that moves chromosomes to the spindle mid-zone in early prometaphase. In addition, in budding yeast meiosis, Mps1 is required for forming stable k-MT attachments, and is then needed to trigger MT de-polymerization to promote poleward chromosome movement. This project tests the hypothesis that Mps1 is a critical regulator of multiple sequential events in chromosome segregation in budding yeast meiosis. This project will elucidate novel mechanisms that drive ordered meiotic chromosome behavior. This project has three objectives. The first is to determine whether several functions of Mps1 are conserved in meiosis, including the MT-dependent sliding of chromosomes from the poles to the spindle mid-zone, termed chromosome gliding. This objective will also test the hypothesis that Mps1 is necessary for regulating this process and determine its regulatory targets. The second objective is to identify the roles that several protein phosphorylation targets of Mps1 have in the three sequential steps in the bi-orientation process: congression to the spindle mid-zone in early prometaphase, attachment of kinetochores to MTs, and depolymerization of kinetochore MTs to trigger poleward chromosome movements. The third objective takes advantage of a separation-of-function allele of MPS1 (mps1-R170S) that exhibits very mild mitotic defects, but profound meiotic defects. Suppressor mutations that improve meiotic chromosome segregation in mps1-R170S mutants have been isolated. These mutants will be evaluated to identify the pathways in meiosis that are extraordinarily sensitive to Mps1 function. Together these experiments will elucidate the manner in which Mps1 helps control and direct chromosomes at multiple steps, from congression, to microtubule attachment, to bi-orientation on the spindle in meiosis.This project is jointly funded by the Cellular Dynamics and Function cluster in the Division of Molecular and Cellular Biosciences, and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.