Mechanisms of Mitotic Activation of the ATM kinase

描述（由申请方提供）：ATM，其突变导致人类常染色体隐性遗传疾病共济失调-毛细血管扩张症（A-T），在维持遗传稳定性和预防癌症形成中起关键作用。ATM是一种PI-3样激酶，在DNA损伤反应中起传感器和信号转导器的作用。目前，ATM的功能研究主要集中在其在电离辐射诱导的DNA双链断裂的细胞反应中的重要作用。然而，由于A-T表型的复杂性和许多A-T表型不能简单地解释为缺乏最佳的DNA损伤反应，ATM的功能在没有DNA损伤的情况下，必须进一步检查。我们发现ATM是激活纺锤体检查点所必需的，纺锤体检查点是一个通过延迟姐妹染色单体分离来防止染色体错误分离的过程。我们的初步数据表明，ATM被激活在有丝分裂过程中的DNA损伤的情况下。ATM的有丝分裂依赖性激活需要功能性Aurora-B。此外，我们发现Aurora-B在体外和体内都磷酸化ATM的Ser 1403。深入研究发现，Aurora-B在有丝分裂期间与ATM相关，而ATM是Bub 1活性所必需的。此外，我们发现ATM磷酸化Bub 1（Ser 314）和Mad 1（Ser 214）。我们的一般假设是，ATM的有丝分裂激活由Aurora-B控制，并在纺锤体检查点的调节中具有功能意义。因此，我们建议研究ATM的有丝分裂激活的机制，并在纺锤体检查点的ATM通路进行剖析。提出了三个具体目标。目的1探讨ATM激活的分子机制.目的2研究ATM Ser 1403磷酸化对有丝分裂进程和纺锤体检查点的作用。目的3研究ATM下游靶点的有丝分裂依赖性磷酸化的功能意义.我们这个项目的长期目标是更好地了解ATM在有丝分裂细胞周期控制中的作用，作为深入了解致癌，细胞生长和细胞死亡的一般机制的基础。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，并找到治疗这种疾病的方法。公共卫生相关性：本研究的目的是通过确定控制有丝分裂纺锤体检查点的上游和下游调控途径来研究ATM在该过程中的新作用。阐明ATM在基本细胞周期调控中的作用将有助于理解共济失调-毛细血管扩张症的病因。此外，这项研究将为肿瘤发生的一般机制提供新的见解，并阐明癌症治疗。

DESCRIPTION (provided by applicant): 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 cannot 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. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to study a novel role of ATM in the mitotic spindle checkpoint by determining the upstream and downstream regulatory pathways controlling the process. Elucidating the role of ATM in basic cell cycle control will help understand the cause of Ataxia-Telangiectasia. Further the study will provide novel insight into general mechanisms of tumorigenesis and shed light on cancer treatment.