Dissecting the interplay between forces and dynamics of the mitotic apparatus and kinetochore attachments

细胞分裂，即从一个细胞产生两个细胞的过程，是生命所必需的。单个细胞经过连续的细胞分裂产生完全发育的生物体。此外，在任何生物体中，死亡细胞通过细胞分裂不断被新细胞取代。细胞分裂的一个关键过程是将复制的DNA平均分配到两个子细胞中，这一过程称为有丝分裂。在有丝分裂过程中，DNA浓缩成染色体，每个染色体由两个姐妹染色单体组成，细胞骨架重组成一种称为有丝分裂纺锤体的结构。有丝分裂纺锤体的微管（MT）通过连接到专门的蛋白质结构（组装在每个姐妹染色单体上的动粒（KT））与染色体相互作用。有丝分裂纺锤体的MT可以产生可以在细胞内移动染色体的力，并最终将姐妹染色单体分离并将它们传递到相反的两极，确保形成具有正确DNA含量的两个子细胞。了解调节有丝分裂染色体分离的机制是我们理解生命如何维持和繁殖的一个关键方面。本研究项目探讨了有丝分裂器内产生力的机制，这些力导致染色单体的运动，从而使它们在有丝分裂过程中准确分离。这项研究的结果将广泛传播。此外，该项目将提供跨学科研究培训和教育的机会。最后，一个外展活动，（5-8年级）关于细胞分裂，将在布莱克斯堡自然中心和当地学校开发并提供作为一项永久性活动本项目的具体目标是剖析有丝分裂器和动粒的力和动力学之间的相互作用在特定的有丝分裂阶段的附着状态。中心假设是，不仅有丝分裂纺锤体产生的力和有丝分裂器的动力学对于确保正确的KT附着和准确的染色体分离是重要的，而且反过来，KT附着状态（例如，正确对不正确）可以影响有丝分裂器的动力学和有丝分裂纺锤体内力的分布。该项目的总体目标将通过解决以下目标来实现：1.定量分析KT附着类型和促进和维持纺锤体极分离所需的运动舞蹈纤维长度/角度之间的相互作用。2.定义MT极向通量和KT机械性质在纠正KT错误附着中的独立作用。3.确定控制后期染色体动力学的有丝分裂器的机械特性。定量实验方法将与数学建模相结合，以达到超越细胞和分子机制的纯粹理解的知识水平，并允许对这些机制如何响应扰动进行预测。该项目还将产生更广泛的影响，这将通过各个领域的举措来确保，包括研究传播，研究生和本科生的跨学科培训以及K-12学生的推广。

Cell division, the process of generating two cells from one, is essential to life. A single cell undergoes consecutive cell divisions to generate a fully developed organism. Moreover, within any organism, dying cells are continuously replaced by new cells via cell division. A key process in cell division is the equal partitioning of the replicated DNA into two daughter cells, a process known as mitosis. During mitosis, the DNA condenses into chromosomes, each constituted by two sister chromatids and the cell cytoskeleton reorganizes into a structure known as the mitotic spindle. The microtubules (MTs) of the mitotic spindle interact with the chromosomes by connecting to specialized protein structures, the kinetochores (KTs) that assemble on each sister chromatid. The MTs of the mitotic spindle can produce forces that can move the chromosomes within the cell and eventually separate the sister chromatids and deliver them to opposite poles, ensuring formation of two daughter cells with correct DNA content. Understanding the mechanisms that regulate mitotic chromosome segregation is a key aspect of our understanding of how life is maintained and propagated. This research project explores the mechanisms responsible for generation of forces within the mitotic apparatus that lead to movement of chromatids such that they are accurately separated during mitosis. The findings of this research will be communicated and disseminated broadly. Moreover, the project will offer opportunities for interdisciplinary research training and education. Finally, an outreach activity, designed for teaching children (grades 5-8) about cell division, will be developed and offered as a permanent activity at the SEEDS - Blacksburg Nature Center and to local schools (through the Biological Sciences Outreach Program).The specific objective of this project is to dissect the interplay between forces and dynamics of the mitotic apparatus and kinetochore (KT) attachment state during specific mitotic stages. The central hypothesis is that not only the forces produced by the mitotic spindle and the dynamics of the mitotic apparatus are important to ensure correct KT attachment and accurate chromosome segregation, but that, in turn, the KT attachment state (e.g., correct vs. incorrect) can influence the dynamics of the mitotic apparatus and the distribution of forces within the mitotic spindle. The overall objective of this project will be achieved by addressing the following aims: 1. Quantitatively dissect the interplay between KT attachment types and kinetochore-fiber length/angle required for promoting and maintaining spindle pole separation. 2. Define the independent roles of MT poleward flux and KT mechanical properties in correction of KT mis-attachments. 3. Identify the mitotic apparatus mechanical properties that control anaphase chromosome dynamics. Quantitative experimental approaches will be combined with mathematical modeling to reach a level of knowledge that goes beyond the pure understanding of cellular and molecular mechanisms and allows to make predictions on how such mechanisms respond to perturbations. This project will also have broader impacts, which will be ensured through initiatives in various areas including research dissemination, interdisciplinary training of graduate and undergraduate students, and outreach to K-12 students.