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

细胞分裂，即从一个细胞生成两个细胞的过程，对生命至关重要。一个单细胞经过连续的细胞分裂产生一个完全发育的有机体。此外，在任何生物体中，垂死的细胞通过细胞分裂不断地被新细胞所取代。细胞分裂的一个关键过程是复制的DNA相等地分裂成两个子细胞，这一过程被称为有丝分裂。在有丝分裂过程中，DNA凝聚成染色体，每条染色体由两个姐妹染色单体组成，细胞骨架重组成一个称为有丝分裂纺锤体的结构。有丝分裂纺锤体的微管（MTs）通过连接在每个姐妹染色单体上组装的特殊蛋白质结构着丝点（KTs）与染色体相互作用。有丝分裂纺锤体的mt可以产生力量，使细胞内的染色体移动，最终分离姐妹染色单体，并将它们运送到相反的极点，确保形成两个具有正确DNA含量的子细胞。理解调节有丝分裂染色体分离的机制是我们理解生命是如何维持和繁殖的一个关键方面。本研究项目探索了在有丝分裂装置内产生力的机制，这些力导致染色单体的运动，从而使它们在有丝分裂期间准确分离。这项研究的结果将得到广泛的宣传和传播。此外，该项目将提供跨学科研究、培训和教育的机会。最后，一项旨在教授儿童（5-8年级）细胞分裂的外展活动将在SEEDS - Blacksburg自然中心和当地学校（通过生物科学外展计划）开发并作为一项永久性活动提供。本项目的具体目的是剖析在特定的有丝分裂阶段有丝分裂装置和着丝点（KT）附着状态的力和动力学之间的相互作用。中心假设是，不仅有丝分裂纺锤体产生的力和有丝分裂装置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，正确与不正确）可以影响有丝分裂装置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：定量剖析KT附着类型与促进和维持纺锤杆分离所需的着丝纤维长度/角度之间的相互作用。2. 定义MT极向通量和KT力学性能在KT错附校正中的独立作用。3. 鉴定控制后期染色体动力学的有丝分裂装置机械特性。定量实验方法将与数学建模相结合，以达到超越对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做出预测。该项目还将产生更广泛的影响，这将通过在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向K-12学生提供服务。

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.