Regulation of cell division by mitotic kinases

描述（由申请人提供）：调节细胞分裂是维持基因组完整性所必需的。有缺陷的调节导致不平等的染色体分离和非整倍体，这与人类有丝分裂中的癌症和减数分裂中的妊娠损失和发育缺陷密切相关。许多复杂的细胞分裂动力学是由几个关键的调节激酶控制的。其中一种激酶，Aurora B，定位于着丝粒直到后期，并调节染色体与有丝分裂纺锤体的附着。在后期开始时，极光B重新分配到纺锤体中间区并控制后期微管动力学和细胞动力学。激酶定位的变化和与其他调节蛋白的相互作用表明磷酸化的不同模式，这将允许单个激酶在不同的时间和地点调节多个过程。该建议的重点是在活细胞中以高时间和空间分辨率检查磷酸化动力学，以测试如何控制这些动力学的模型。Aurora B的一个关键作用是确保所有染色体以正确的形态附着在纺锤体微管上，从而使染色体在后期准确分离。必须产生信号来区分正确和不正确的附件，以便纠正错误。第一个具体目标是测试单个着丝粒中极光B信号的差异模型。纺锤体微管施加的力在着丝粒上产生张力，这可能通过将基质与集中在内部着丝粒的激酶物理分离来调节着丝粒底物的磷酸化。第二个具体目标将检查极光B和其他有丝分裂激酶在着丝粒之间的相互作用。有证据表明极光B、BubR1、Plk1和Chk1之间存在相互作用。通过使用小分子抑制剂和RNAi，结合活细胞磷酸化动力学和激酶抑制的定量测量，将测试多种激酶在着丝粒信号网络中起作用的模型。Aurora B的功能和定位在后期发生了巨大的变化，这表明复杂的空间和时间磷酸化模式可能允许单个a激酶调节多个细胞过程。第三个具体目标将确定极光B和对立磷酸酶如何在后期促进位点特异性磷酸化动力学的开关。这些研究将有助于理解(1)调节细胞分裂的基本机制和(2)Aurora B抑制剂的作用，它们正在进行癌症治疗的临床试验。

DESCRIPTION (provided by applicant): Regulation of cell division is necessary to maintain genome integrity. Defective regulation leads to unequal chromosome segregation and aneuploidy, which is strongly associated with human cancer in mitotic divisions and pregnancy loss and developmental defects in meiosis. Much of the complex dynamics of cell division is controlled by a few key regulatory kinases. One of these kinases, Aurora B, localizes to the centromere until anaphase and regulates the attachments of chromosomes to the mitotic spindle. At anaphase onset Aurora B redistributes to the spindle midzone and controls anaphase microtubule dynamics and cytokinesis. Changes in kinase localization and interactions with other regulatory proteins suggest varying patterns of phosphorylation that would allow a single kinase to regulate multiple processes at different times and places. This proposal focuses on examining phosphorylation dynamics with high temporal and spatial resolution in living cells to test models for how these dynamics are controlled. A key role of Aurora B is to ensure that all chromosomes attach to spindle microtubule in the correct configuration, so that chromosomes segregate accurately in anaphase. Signals must be generated to distinguish correct and incorrect attachment, so that errors can be corrected. The first specific aim will test a model for differential Aurora B signaling at individual centromeres. Forces exerted by spindle microtubules create tension across the centromere, which may regulate phosphorylation of a kinetochore substrate by physically separating the substrate from the kinase, which is concentrated at the inner centromere. The second specific aim will examine the interplay between Aurora B and other mitotic kinases at the centromere. There is evidence for interactions between Aurora B, BubR1, Plk1, and Chk1. By combining quantitative measurements of phosphorylation dynamics in living cells with kinase inhibition, using small molecule inhibitors and RNAi, a model in which multiple kinases act in a signaling network at the centromere will be tested. Aurora B function and localization change dramatically in anaphase, suggesting that complex spatial and temporal phosphorylation patterns may allow a single a kinase to regulate a multiple cellular process. The third specific aim will determine how both Aurora B and opposing phosphatases contribute to a switch in site- specific phosphorylation dynamics in anaphase. These studies will contribute to an understanding of (1) basic mechanisms regulating cell division and (2) the effects of Aurora B inhibitors, which are in clinical trials for cancer therapy. Public Health Relevance: Proper regulation of cell division ensures that daughter cells inherit the correct genetic material. Errors during division lead to cells with genetic abnormalities that are strongly associated with human cancer, pregnancy loss, and developmental defects. The goal of this proposal is to understand the function of a key regulatory protein, which is a promising target for cancer therapy, in cell division.