Characterization of the Mitotic Exit Network

真核细胞必须在时间上协调不同的细胞过程，以确保细胞的保真度。 增殖细胞周期过程的执行或时间协调的缺陷增加了遗传性 不稳定和促进癌症。因此，研究细胞周期保守的机制具有重要意义 规定酿酒酵母有丝分裂出口网络（MEN）是协调几个关键因素。 有丝分裂退出期间的细胞周期过程，包括细胞周期蛋白依赖性激酶（CDK）失活，胞质分裂， 有丝分裂纺锤体解体和G1基因表达的激活。Mob 1-Dbf 2激酶复合物是 它是MEN的组成部分，与人Mob 1A-LATS激酶复合物相邻，其功能是 哺乳动物肿瘤抑制因子酵母Mob 1-Dbf 2与胞质分裂、Cdc 14的激活有关 磷酸酶（通过使CDK磷酸化失活而使有丝分裂退出）和有丝分裂纺锤体功能 通过调节Aurora激酶。尽管如此，酵母的功能机制和底物， 哺乳动物Mob 1-Dbf 2激酶未知。拟议工作的目标是确定 Mob 1-Dbf 2激酶复合物在时间上协调胞质分裂与有丝分裂退出和染色体 种族隔离我们提出三个目标。第一个目的是确定Mob 1-Dbf 2在胞质分裂中的作用。我们 将进行细胞生物学，生物化学和遗传学的方法来测试的假设，MEN控制 通过调节靶向膜沉积和通过激活RAM（Ace 2的调节 转录因子和极化形态发生）信号网络，控制胞质分裂，基因 表达和其他功能。第二个目的是确定Mob 1-Dbf 2激酶复合物的作用 在有丝分裂退出和胞质分裂期间Cdc 14磷酸酶活化。我们将测试Mob 1- Dbf 2激酶直接诱导Cdc 14磷酸酶从核仁释放，并将定义上位性 Mob 1-Dbf 2和Cdclp与胞质分裂的关系。第三个目标是确定 有丝分裂检查点信号中的Mob 1-Dbf 2。我们将测试Mob 1-Dbf 2是必需的假设， 极光依赖的检查点信号。考虑到Mob 1-Dbf 2的保守性，拟议的工作将有助于 解决所有MEN相关信号网络的功能，包括人类hMob 1A-LATS 1肿瘤 抑制途径，并将有助于阐明癌症发展的潜在机制。

Eukaryotic cells must temporally coordinate diverse cellular processes to ensure the fidelity of cell proliferation. Defects in the execution or temporal coordination of cell cycle processes increase genetic instability and promote cancer. Thus, it is important to resolve the mechanisms of conserved cell cycle regulations. The Saccharomyces cerevisiae Mitotic Exit Network (MEN) is essential for coordinating several cell cycle processes during mitotic exit, including cyclin dependent kinase (CDK) inactivation, cytokinesis, mitotic spindle disassembly and activation of G1 gene expression. The Mob1-Dbf2 kinase complex is a key component of MEN and is orthologous to the human Mob1A-LATS kinase complex, which functions as mammalian tumor suppressor. Yeast Mob1-Dbf2 has been implicated in cytokinesis, activation of Cdc14 phosphatase (which enables mitotic exit by inactivating CDK phosphorylations) and mitotic spindle function via regulation of Aurora kinase. Nevertheless, the functional mechanisms and substrates of yeast and mammalian Mob1-Dbf2 kinases are not known. The goal of the proposed work is to determine how the Mob1-Dbf2 kinase complex temporally coordinates cytokinesis with mitotic exit and chromosome segregation. We propose three aims. The first aim is to determine the role of Mob1-Dbf2 in cytokinesis. We will conduct cell biological, biochemical and genetic approaches to test the hypothesis that MEN controls cytokinesis by regulating targeted membrane deposition and by activating the RAM (Regulation of Ace2 transcription factor and polarized Morphogenesis) signaling network, which controls cytokinesis, gene expression and other functions. The second aim is to determine the role of the Mob1-Dbf2 kinase complex in Cdc14 phosphatase activation during mitotic exit and cytokinesis. We will test the hypothesis that Mob1- Dbf2 kinase directly induces Cdc14 phosphatase release from the nucleolus and will define the epistatic relationship of Mob1-Dbf2 and Cdclp with respect to cytokinesis. The third aim is to determine the role of Mob1-Dbf2 in mitotic checkpoint signaling. We will test the hypothesis that Mob1-Dbf2 is required for Aurora-dependent checkpoint signaling. Given the conservation of Mob1-Dbf2, the proposed work will help resolve the function of all MEN-related signaling networks, including the human hMob1A-LATS1 tumor suppressor pathway, and will help elucidate the underlying mechanisms of cancer development.