Mechanisms of Mitotic Activation of the ATM kinase

摘要 ATM，其突变导致人类常染色体隐性遗传病共济失调- 毛细血管扩张症(A-T)在维持遗传稳定性和预防 癌症的形成。ATM是一种类似PI-3的激酶，起传感器和信号的作用 DNA损伤反应中的换能器。目前，对自动柜员机的功能研究大多 关注其在细胞对电离辐射诱导的DNA双链反应中的重要作用 链子断了。然而，由于A-T表型的复杂性和许多A-T 表型不能简单地用缺乏最佳的DNA损伤反应来解释， 在没有DNA损伤的情况下，ATM的功能必须进一步检查。我们有 发现激活磁盘轴检查点需要自动柜员机，该过程 通过延迟姐妹染色单体分离来防止染色体错误分离。我们的 初步数据显示，ATM在有丝分裂期间被激活，在没有 DNA损伤。有丝分裂依赖的ATM激活需要有功能的Aurora-B。 此外，我们在体外和体外都发现Aurora-B在Ser1403处使ATM磷酸化。 活着。深入研究发现，Aurora-B与ATM在有丝分裂和 Bub1的活动需要自动取款机。进一步我们发现ATM使Bub1磷酸化 (在Ser314)和Mad 1(在Ser214)。我们在这项提议中的一般假设是有丝分裂 ATM的激活受Aurora-B的调控，在调节ATM中具有功能意义 主轴检查点。因此，我们建议研究有丝分裂激活的机制。 并对主轴检查点中的ATM路径进行剖析。三个具体目标是 建议。目的1将重点研究ATM激活的分子机制。 目的2将研究ATM Ser1403磷酸化在有丝分裂进程中的作用以及 主轴检查点。目标3将重点研究有丝分裂的功能意义- 依赖于其下游靶标的ATM磷酸化。我们的长期目标是 该项目旨在更好地了解ATM在有丝分裂细胞周期控制中的作用，以此为基础 提供对癌症发生、细胞生长和细胞死亡的一般机制的见解。 剖析ATM在有丝分裂中的重要作用可能有助于理解许多A-T表型 找到治疗这种疾病的方法。

SUMMARY ATM, mutation of which leads to the human autosomal recessive disorder Ataxia- Telangiectasia (A-T), plays a critical role in maintaining genetic stability and preventing cancer formation. ATM is a PI-3 like kinase that functions as a sensor and signal transducer in DNA damage responses. Currently, most of the functional studies of ATM focus on its essential role in the cellular response to ionizing radiation-induced DNA double strand breaks. However, because of the complexity of A-T phenotypes and many of the A-T phenotypes can not be simply explained by the lack of an optimal DNA damage response, functions of ATM in the absence of DNA damage must be further examined. We have found that ATM was required for the activation of the spindle checkpoint, a process that protects against chromosome missegregation by delaying sister chromatid separation. Our preliminary data demonstrated that ATM was activated during mitosis in the absence of DNA damage. The mitosis-dependent activation of ATM requires functional Aurora-B. Furthermore we found that Aurora-B phosphorylated ATM at Ser1403 both in vitro and in vivo. In depth studies have found that Aurora-B associated with ATM during mitosis and ATM was required for the activity of Bub1. Further we found that ATM phosphorylated Bub1 (at Ser314) and Mad 1(at Ser214). Our general hypothesis in this proposal is that mitotic activation of ATM is governed by Aurora-B and has functional significance in regulation of the spindle checkpoint. Therefore we propose to study the mechanisms of mitotic activation of ATM and to dissect the ATM pathways in the spindle checkpoint. Three specific aims are proposed. Aim 1 will focus on investigate the molecular mechanism of the ATM activation. Aim 2 will study the role of ATM Ser1403 phosphorylation on mitotic progression and the spindle checkpoint. Aim 3 will focus on studying the functional significance of mitotic- dependent ATM phosphorylation of its downstream target. Our long-term goal of this project is to better understand the role of ATM in mitotic cell cycle control as a basis for providing insights into general mechanisms of carcinogenesis, cell growth and cell death. Dissecting the important role of ATM in mitosis may help understand many A-T phenotypes and find a cure for the disease.