Functional Characterization of the ATM Gene Product

ATM 基因产物的功能表征

• 批准号: 7409069
• 负责人: Michael B Kastan
• 金额: $ 35.56万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7409069
• 关键词: ATM activation; ATM gene; Ataxia-Telangiectasia-Mutated protein kinase; Biological Models; Cancer Etiology; Cells; Chloroquine; Chromatin; DNA; DNA Damage; Data; Dependence; Development; Dissociation; Enzymes; Event; Funding; Genetic; Grant; Higher Order Chromatin Structure; Malignant Neoplasms; Molecular; Mus; Nature; Oncogenes; Pathway interactions; Phosphorylation; Post-Translational Protein Processing; Proteins; Radioprotection; Role; Serine; Signaling Molecule; Vertebral column; Whole-Body Irradiation; ataxia telangiectasia mutated protein; cancer prevention; cancer therapy; chemical carcinogen; coping; dimer; irradiation; mouse model; phosphodiester; prevent; research study; response; success

DESCRIPTION (provided by applicant): Understanding the molecular control of cellular responses to DNA damage has significance for both cancer development and cancer therapies. Among the most critical types of DNA damage with which our cells need to cope are breaks in the phosphodiester backbone. The ATM protein kinase is a central signaling molecule in modulating cellular responses to DNA breakage. In the previous funding period of this grant, significant progress was made in elucidating the mechanisms involved in the activation of the ATM kinase. In addition, we were able to identify specific protein targets of the ATM enzyme and to decipher the functional significance of these phosphorylation events. In this application, we build upon these successes and propose experiments that will further elucidate molecular mechanisms involved in cellular responses to DNA breakage and other types of DNA damage. We found that ATM exists in cells as a homodimer and is activated after DNA damage by an intermolecular autophosphorylation on serine 1981 that causes dissociation of the dimer. We recently identified an additional serine in the ATM protein that becomes phosphorylated in response to DNA damage. Experiments are proposed to explore the functional significance of this new post-translational modification. In particular, we expect that this phosphorylation event contribute to modulating the cellular activities of the ATM kinase after its initial activation. In addition, experiments are proposed that will explore the nature of ATM interactions with chromosomal proteins so that we can better understand how ATM associates with chromatin and senses alterations in higher order chromatin structures to become activated. The elucidation of the ATM activation mechanism also led to our ability to activate the enzyme in the absence of detectable DNA damage. This led to proof-of-principle experiments demonstrating that activation of the ATM-p53 pathway prior to irradiation leads to radioprotection of mice exposed to total body irradiation. Preliminary data is also presented demonstrating that activation of the ATM-p53 pathway can prevent cancer development in multiple mouse models, including cancers caused by ionizing irradiation, chemical carcinogens, or activated oncogenes. Experiments are proposed to further explore the molecular mechanisms involved in both the radioprotective effects and the cancer preventative effects of ATM activation.

描述（由申请人提供）：了解细胞对 DNA 损伤反应的分子控制对于癌症发展和癌症治疗都具有重要意义。我们的细胞需要应对的最关键的 DNA 损伤类型是磷酸二酯主链的断裂。 ATM 蛋白激酶是调节细胞对 DNA 断裂反应的核心信号分子。在本次资助的前一个资助期间，在阐明 ATM 激酶激活机制方面取得了重大进展。 此外，我们能够识别 ATM 酶的特定蛋白质靶点并破译这些磷酸化事件的功能意义。在此应用中，我们在这些成功的基础上提出了实验，以进一步阐明细胞对 DNA 断裂和其他类型 DNA 损伤的反应所涉及的分子机制。我们发现 ATM 以同型二聚体形式存在于细胞中，并在 DNA 损伤后通过丝氨酸 1981 上的分子间自磷酸化而被激活，从而导致二聚体解离。我们最近在 ATM 蛋白中发现了一个额外的丝氨酸，它会因 DNA 损伤而被磷酸化。建议进行实验来探索这种新的翻译后修饰的功能意义。特别是，我们预计这种磷酸化事件有助于在 ATM 激酶初始激活后调节其细胞活性。此外，还提出了实验来探索 ATM 与染色体蛋白相互作用的本质，以便我们更好地了解 ATM 如何与染色质结合并感知高级染色质结构的变化以被激活。 ATM 激活机制的阐明也使我们能够在没有可检测到的 DNA 损伤的情况下激活该酶。这引发了原理验证实验，证明在辐射之前激活 ATM-p53 通路可以对暴露于全身辐射的小鼠产生辐射防护。初步数据还表明，ATM-p53 通路的激活可以预防多种小鼠模型中的癌症发展，包括电离辐射、化学致癌物或激活的癌基因引起的癌症。建议通过实验进一步探索 ATM 激活的辐射防护作用和癌症预防作用所涉及的分子机制。