Functional Characterization of the ATM Gene Product

ATM 基因产物的功能表征

• 批准号: 6920225
• 负责人: Michael B Kastan
• 金额: $ 37.5万
• 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 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6920225
• 关键词: DNA binding protein; DNA damage; animal genetic material tag; biological signal transduction; cancer prevention; cellular pathology; enzyme activity; gene expression; gene mutation; immunoprecipitation; ionizing radiation; laboratory mouse; molecular oncology; p53 gene /protein; phosphorylation; posttranslational modifications; protein protein interaction; protein structure function; radiation genetics; radiosensitizer; serine threonine protein kinase; tissue /cell culture; tumor suppressor genes; tumor suppressor proteins; western blottings; yeast two hybrid system

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癌症发展和癌症治疗都具有重要意义。我们的细胞需要科普的最关键类型的DNA损伤是磷酸二酯骨架的断裂。ATM蛋白激酶是调节细胞对DNA断裂反应的中心信号分子。在该赠款的上一个资助期，在阐明ATM激酶激活所涉及的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。在这个应用中，我们建立在这些成功的基础上，并提出实验，将进一步阐明DNA断裂和其他类型的DNA损伤的细胞反应所涉及的分子机制。我们发现ATM在细胞中以同源二聚体的形式存在，并在DNA损伤后被丝氨酸1981上的分子间自磷酸化激活，从而导致二聚体的解离。我们最近在ATM蛋白中发现了一个额外的丝氨酸，它在DNA损伤时被磷酸化。实验拟探讨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调节ATM激酶的细胞活性后，其初始激活。此外，实验提出，将探讨ATM与染色体蛋白质的相互作用的性质，使我们可以更好地了解ATM如何与染色质和感官的变化，在更高层次的染色质结构被激活。ATM激活机制的阐明也使我们能够在没有可检测到的DNA损伤的情况下激活酶。这导致了原理验证实验，证明在照射前激活ATM-p53途径导致暴露于全身照射的小鼠的辐射保护。初步数据还表明，激活的ATM-p53通路可以防止癌症的发展，在多种小鼠模型，包括电离辐射，化学致癌物，或激活的癌基因引起的癌症。实验拟进一步探讨ATM激活的辐射防护作用和癌症预防作用的分子机制。