Computational Modeling and Analysis of Kinetochore Dynamics during Mitosis

描述（由申请人提供）：在有丝分裂期间，染色体排列整齐，以便它们可以通过有丝分裂纺锤体正确分离。在有丝分裂过程中，正确的染色体排列和随后的分离对于防止染色体不均匀分离的非整倍体至关重要。非整倍体与体外细胞的致瘤性转化有关，在人类癌细胞中也经常观察到。虽然已知微管在有丝分裂过程中调节染色体的排列，但对与每个染色体相关的多个微管的动力学如何协调以实现正确的染色体排列的机制理解仍然难以捉摸。为了建立一个坚实的理论框架来重新定义和转移有丝分裂领域的关键问题，特别是应用于与每个染色体相关的多个微管的协调和调节，我们将开发一个预测性的随机计算模型，并进行实验来验证模型的预测。我们将利用白色念珠菌作为模型系统，因为它具有独特的特性，即可以操纵它进行有丝分裂，每条染色体上有单个微管附着，或每条染色体上有多个微管附着。具体而言，我们将(1)利用电子显微镜方法建立白色念珠菌有丝分裂纺锤体的三维几何形状，(2)建立野生型白色念珠菌有丝分裂纺锤体的随机计算模型，以及(3)利用白色念珠菌预测计算模型进行假设检验。虽然已经证明异常的微管动力学导致染色体不稳定，但我们的研究将区分微管动力学的协调是否可能对有丝分裂期间染色体分离的保真度很重要，或者微管动力学的调节是否允许适当的染色体附着转换。由于许多重要的化疗药物通过破坏微管动力学来阻止有丝分裂，因此对微管动力学在调节染色体动力学中的作用的进一步了解将为解释重要化疗药物的作用机制提供新的背景。总的来说，这个项目将提供一个重要的例子，说明在调查的早期阶段如何将定量建模与实验相结合，这样计算建模不仅可以用来检验假设，还可以用来设计实验，并随着项目的进行而完善具体的假设。

DESCRIPTION (provided by applicant): During mitosis, chromosomes are aligned so that they can be properly segregated by the mitotic spindle. Proper chromosome alignment and subsequent separation during mitosis is critical in preventing aneuploidy, a condition in which chromosomes are not equally segregated. Aneuploidy has been implicated in tumorigenic transformation of cells in vitro, and is commonly observed in human cancer cells. While it is known that microtubules regulate the alignment of chromosomes during mitosis, a mechanistic understanding of how the dynamics of multiple microtubules associated with each individual chromosome are coordinated to achieve proper chromosome alignment remains elusive. To establish a solid theoretical framework to redefine and shift key questions in the field of mitosis, specifically as applied to the coordination and regulation of multiple microtubules associated with each individual chromosome, we will develop a predictive, stochastic computational model, and perform experiments to test predictions of the model. We will exploit Candida albicans as a model system because it has the unique property that it can be manipulated to undergo mitosis with either a single microtubule attachment per chromosome, or with multiple microtubule attachments per chromosome. Specifically, we will (1) establish the 3D geometry of the C. albicans mitotic spindle using electron microscopy methods, (2) develop a stochastic computational model for the wild-type C. albicans mitotic spindle, and (3) leverage the C. albicans predictive computational model for hypothesis testing. While it has been shown that aberrant microtubule dynamics lead to chromosomal instability, our studies will distinguish whether it is likely that the coordination of the microtubule dynamics are important for the fidelity of chromosome segregation during mitosis, or whether regulation of microtubule dynamics allows for proper chromosome attachment turnover. Because many significant chemotherapy drugs act to stop mitosis by disrupting microtubule dynamics, an improved understanding for the role of microtubule dynamics in regulating chromosome dynamics will provide a new context for interpreting the mechanism of action for important chemotherapy drugs. In general, this project will provide an important example of how quantitative modeling can be integrated with experiments at the earliest stages of investigation, such that computational modeling will not only be used to test hypotheses, but will also be used to design experiments and refine specific hypotheses as the project proceeds. PUBLIC HEALTH RELEVANCE: In this project, we seek to understand how chromosomes are properly aligned and segregated during cell division. Proper chromosome alignment and subsequent separation during mitosis is critical in preventing aneuploidy, a condition in which chromosomes are not equally segregated. Aneuploidy has been implicated in birth defects such as Down syndrome, and is commonly observed in human cancer cells.