A Novel Pathway Involving ATM, PP1 and I-2

涉及 ATM、PP1 和 I-2 的新途径

• 批准号: 8094336
• 负责人: BO XU
• 金额: $ 27.17万
• 依托单位: METHODIST HOSPITAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8094336
• 关键词: ATM function; ATM gene; Affinity; Antibodies; Ataxia Telangiectasia; Ataxia-Telangiectasia-Mutated protein kinase; Binding; Carcinogenesis Mechanism; Cell Cycle; Cell Cycle Checkpoint; Cell Cycle Progression; Cell Death; Cell physiology; Complex; Coupled; DNA Damage; DNA Repair; DNA biosynthesis; Data; Dissociation; Elements; Ensure; Genotoxic Stress; Goals; Health; Hereditary Disease; Human; Immunologic Deficiency Syndromes; In Vitro; Indium; Ionizing radiation; Lead; Light; Link; Malignant Neoplasms; Mammalian Cell; Maps; Mediating; Molecular; Pathway interactions; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Predisposition; Process; Protein Serine/Threonine Phosphatase; Protein phosphatase; Proteins; Radiation Induced DNA Damage; Radiation Tolerance; Recovery; Regulation; Replication Initiation; Role; S Phase; Sepharose; Serine; Signal Pathway; Signal Transduction; Site; ataxia telangiectasia mutated protein; base; cell growth; inhibitor/antagonist; insight; loss of function mutation; novel; research study; response

DESCRIPTION (provided by applicant): Our long-term goal of this project is to elucidate the molecular mechanism of ATM in DNA damage and repair pathways as an attempt to further understand Ataxia Telangiectasia, an autosomal recessive genetic disease associated with loss-of-function mutations in the ATM gene. The ATM protein kinase is considered a critical element in determining cellular responses to ionizing radiation (IR). ATM is activated after DNA damage and signals many key regulators in DNA damage pathways by phosphorylation to initiate an optimal response. Of these, Protein Phosphatase 1 (PP1), a major eukaryotic protein serine/threonine phosphatase that regulates a variety of cellular function in response to DNA damage, is activated in an ATM-dependent manner after IR. However, detailed mechanisms on how ATM activates PP1 remain further explored. We have recently demonstrated that ATM is required for the rapid dissociation of PP1 from its regulatory subunit, Inhibitor-2 (I-2) in response to IR. Furthermore, we found that ATM phosphorylated I-2 at Serine 43 after DNA damage, leading to dissociation of the PP1/I-2 complex and activation of PP1. Our preliminary data in this proposal demonstrated that the ATM/PP1/I-2 pathway was required for the IR-induced S phase and G2/M checkpoints. Further, we found Brca1, Cdc7, and Chk2 presented in a complex with the phosphorylated form of I-2. To dissect the upstream and downstream elements of the ATM/PP1/I-2 pathway and establish links of the pathway to the cell cycle machinery, we propose three specific aims: 1). Investigate the role of Brca1 in ATM-mediated I-2 Ser 43 phosphorylation and PP activation in response to IR; 2) Investigate the role of the ATM/PP1/I-2 pathway on Cdc7 inactivation and the S-phase checkpoint; 3). Investigate the mechanism by which the ATM/PP1/I-2 pathway activates the G2/M checkpoint by studying I-2 mediated Chk2 activation and Chk2 phosphorylation/activation of PP1 in response to IR. Completion of these studies will provide insights into roles and mechanisms of the ATM kinase and, in the process, shed light on general mechanisms involved in the cellular response to DNA damage. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to investigate the functional importance of an ATM- mediated signaling pathway in response to radiation-induced DNA damage as an attempt to further understand the cause of Ataxia-Telangiectasia (A-T), an autosomal recessive genetic disease associated with loss-of-function mutations in the ATM gene.

描述（由申请人提供）：我们的长期目标是阐明ATM在DNA损伤和修复途径中的分子机制，以进一步了解共济失调毛细血管扩张症，这是一种与ATM基因功能丧失突变相关的常染色体隐性遗传病。ATM蛋白激酶被认为是决定细胞对电离辐射（IR）反应的关键因素。ATM在DNA损伤后被激活，并通过磷酸化向DNA损伤通路中的许多关键调节因子发出信号，以启动最佳反应。其中，蛋白磷酸酶1 （PP1）是一种主要的真核蛋白丝氨酸/苏氨酸磷酸酶，在响应DNA损伤时调节多种细胞功能，在IR后以atm依赖的方式被激活。然而，关于ATM如何激活PP1的详细机制仍有待进一步探索。我们最近证明，ATM是PP1与其调控亚基抑制剂-2 （I-2）在IR反应中快速解离所必需的。此外，我们发现ATM在DNA损伤后磷酸化I-2的丝氨酸43，导致PP1/I-2复合物的解离和PP1的激活。我们在本提案中的初步数据表明，ATM/PP1/I-2通路是ir诱导的S期和G2/M检查点所必需的。此外，我们发现Brca1、Cdc7和Chk2与磷酸化形式的I-2呈复合体。为了剖析ATM/PP1/I-2通路的上游和下游元件，并建立该通路与细胞周期机制的联系，我们提出了三个具体目标：1)。研究Brca1在IR下atm介导的I-2 Ser 43磷酸化和PP激活中的作用；2)研究ATM/PP1/I-2通路在Cdc7失活和s期检查点中的作用；3）. 通过研究I-2介导的Chk2激活和Chk2磷酸化/激活PP1对IR的响应，探讨ATM/PP1/I-2通路激活G2/M检查点的机制。这些研究的完成将提供对ATM激酶的作用和机制的见解，并在此过程中阐明参与细胞对DNA损伤反应的一般机制。公共卫生相关性：本提案的目的是研究ATM介导的信号通路在应对辐射诱导的DNA损伤中的功能重要性，以进一步了解共济失调毛细血管扩张症（A-T）的原因，这是一种与ATM基因功能丧失突变相关的常染色体隐性遗传疾病。