Regulation of cell division by mitotic kinases

描述（由申请人提供）：细胞分裂的调节是维持基因组完整性所必需的。调控缺陷导致染色体不均等分离和非整倍体，这与人类有丝分裂中的癌症和减数分裂中的妊娠丢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，直到分裂后期，并调节染色体与有丝分裂纺锤体的连接。在后期开始极光B重新分配到纺锤体中间区和控制后期微管动力学和胞质分裂。激酶定位的变化和与其他调节蛋白的相互作用表明不同的磷酸化模式，这将允许一个单一的激酶在不同的时间和地点调节多个过程。该提案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，以测试这些动力学如何控制的模型。Aurora B的一个关键作用是确保所有染色体以正确的构型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连接，以便可以纠正错误。第一个具体目标是测试单个着丝粒上差异极光B信号的模型。由纺锤体微管施加的力产生跨越着丝粒的张力，这可以通过将底物与集中在内部着丝粒处的激酶物理分离来调节动粒底物的磷酸化。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Aurora B、BubR1、Plk 1和Chk 1之间存在相互作用。通过将活细胞中磷酸化动力学的定量测量与激酶抑制相结合，使用小分子抑制剂和RNAi，将测试多个激酶在着丝粒处的信号网络中起作用的模型。Aurora B的功能和定位在细胞分裂后期发生显著变化，表明复杂的时空磷酸化模式可能允许单个α激酶调节多个细胞过程。第三个具体目标将确定极光B和相反的磷酸酶如何有助于后期位点特异性磷酸化动力学的转换。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，这些抑制剂正在进行癌症治疗的临床试验。 公共卫生相关性：细胞分裂的适当调节确保子细胞继承正确的遗传物质。分裂过程中的错误导致细胞具有与人类癌症，妊娠损失和发育缺陷密切相关的遗传异常。该提案的目标是了解一种关键调节蛋白在细胞分裂中的功能，这是一种有前途的癌症治疗靶点。

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.