Cellular Events Downstream of Mitotic Errors

项目摘要 在动物细胞中，核结构在有丝分裂过程中被完全拆除。虽然染色体 伴随着被改造成紧凑的保护性结构，各种错误来源可以使基因组 细胞分裂时的稳定性受到威胁。染色体分裂本身可能是基因组不稳定的时期 错误，如果纺锤体组装检查点未能确保染色体比对在其之前完成， 种族隔离在某些情况下，前一个细胞周期中的事件，如不完整的DNA复制，使细胞周期发生变化。 有丝分裂时基因组处于危险之中。在其他情况下，有丝分裂后期事件的不协调引起DNA 损害因此，这些潜在错误的下游事件在维持基因组稳定性方面发挥着不可或缺的作用。 越来越多的人了解核组装的快速步骤， 新形成的细胞核中的基因组监视为拟议的研究提供了基础， 解决细胞如何科普有丝分裂错误。该研究提出的核心是概念创新 假设，并寻求对核组装，基因组 监视和胞质分裂。根据新的观察， 染色体有一套特定的蛋白质组成，我们的首要目标是确定核膜如何不同 在错误分离的染色体，测试的假设，这些变化改变膜密封。的影响 这一独特的核膜结构域对核完整性和错误的频率有影响， 分离的染色体重新整合到细胞核中将通过实时成像来确定。我们还将 询问激酶Aurora B在调节落后染色体NE区域差异中的作用。 在落后染色体与主核分离的情况下，我们的结果也将有助于了解 为什么产生的微核具有升级DNA损伤和激发先天免疫信号的属性。的 第二个目标集中在有丝分裂后基因组监视的机制。获得独特的视角 在这个过程中，我们将探讨Nup 153和Nup 50在靶向DNA损伤反应因子中的作用 53 BP 1为监测点。最后，我们将确定是什么激活了授权检查点，这是一个监管事件 在有丝分裂的下游停止细胞分裂的最后一步。在观察到一个强大的连接之间， Nup 153功能丧失和释放检查点，我们假设这是由于 nup 153在核形成和基因组监测中的作用。更广泛地说，我们将测试由以下因素引发的假设： 这种模式：核完整性的丧失-以及对DNA的损伤-是由 当基因组监视机制被破坏时， 暴露了所获得的结果将带来重要的新的见解，以不同的机制， 基因组的完整性，并有助于基本细胞周期调控机制的综合理解。

PROJECT SUMMARY In animal cells, nuclear structure is completely dismantled during the process of mitosis. Although chromosomes are concomitantly remodeled into compact, protective structures, various sources of error can put genome stability at risk at this time of cell division. Chromosome division itself can be a time of genome destabilizing errors, if the spindle assembly checkpoint fails to ensure that chromosome alignment is complete prior to their segregation. In some cases, events in the previous cell cycle, such as incomplete DNA replication, put the genome in jeopardy at mitosis. In other cases, mis-coordination of events in late mitosis gives rise to DNA damage. Events downstream of these potential errors thus play an integral role in maintaining genome stability. A growing body of knowledge about the rapid steps of nuclear assembly and an appreciation for the importance of genome surveillance in newly-formed nuclei provide a foundation for the proposed research designed to address how cells cope with mitotic errors. The research proposed is centered on conceptually innovative hypotheses and seeks to make novel inroads into the inter-connections between nuclear assembly, genome surveillance, and cytokinesis. Building on the new observation that the nuclear envelope at lagging chromosomes has a specific set of constituent proteins, our first aim is to define how the nuclear envelope differs at mis-segregated chromosomes, testing the hypothesis that these changes alter membrane sealing. The impact that this distinctive nuclear envelope domain has on nuclear integrity and the frequency with which mis- segregating chromosomes re-integrate into the nucleus will be determined by live-imaging. We will also interrogate the role of the kinase Aurora B in regulating regional differences at the NE of lagging chromosomes. In cases where the lagging chromosome separates from the main nucleus, our results will also lend insight into why resulting micronuclei have attributes that escalate DNA damage and instigate innate immune signaling. The second aim is focused on mechanisms involved in genome surveillance after mitosis. To gain unique perspective on this process, we will pursue the roles of Nup153 and Nup50 in targeting the DNA damage response factor 53BP1 to surveillance foci. Finally, we will determine what activates the abscission checkpoint, a regulatory event downstream of mitosis that halts the final step of cell division. Having observed a robust connection between loss of Nup153 function and the abscission checkpoint, we hypothesize that this is due to the dual roles of Nup153 in nuclear formation and genomic surveillance. More broadly, we will test the hypothesis prompted by this paradigm: that loss of nuclear integrity --and the damage to DNA that ensues-- are monitored by the abscission checkpoint and become a particularly potent signal when genome surveillance mechanisms are compromised. The results obtained will bring significant new insight into diverse mechanisms that preserve genome integrity and contribute to an integrated understanding of fundamental cell cycle regulatory mechanisms.