Mechanisms of mitochondrial damage in ataxia-telangiectasia

共济失调毛细血管扩张症线粒体损伤的机制

• 批准号: 9105821
• 负责人: Randal Scot Tibbetts
• 金额: $ 22.53万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9105821
• 关键词: ATM gene; ATM wt Allele; Alleles; Ataxia Telangiectasia; Ataxia Telangiectasia Patients; Attenuated; Behavioral; Biochemical Genetics; Cell Nucleus; Cells; Cellular Stress; Cerebellum; ChIP-on-chip; ChIP-seq; Chromatin; Chronic; Cyclic AMP-Responsive DNA-Binding Protein; DNA Damage; DNA Double Strand Break; Data; Deacetylase; Defect; Development; Double Strand Break Repair; Exhibits; Fibroblasts; Gene Expression; Gene Expression Profile; Gene Targeting; Generations; Genes; Genetic Transcription; Genotoxic Stress; Goals; HDAC4 gene; Health; Hereditary Disease; Homeostasis; Ionizing radiation; Knock-in; Knock-in Mouse; Lead; Light; Link; Malignant Neoplasms; Mammalian Cell; Measures; Mediating; Metabolic; Mitochondria; Modeling; Motor; Mus; Mutation; Nerve Degeneration; Nervous System Physiology; Nervous system structure; Neuraxis; Neurodegenerative Disorders; Neurologic; Neuronal Injury; Neurons; Nuclear; Oncogene Deregulation; Oxidative Stress; Pathologic; Pathology; Pathway interactions; Performance; Phenotype; Phosphorylation; Physiology; Play; Predisposition; Protein Kinase; Publishing; Radiation Tolerance; Reactive Oxygen Species; Recruitment Activity; Refractory; Regulation; Role; Signal Transduction; Stress; Structure; Synaptic plasticity; Syndrome; System; Testing; Transactivation; Transcription Repressor/Corepressor; Transcriptional Regulation; Work; ataxia telangiectasia mutated protein; attenuation; defined contribution; disease-causing mutation; genetic approach; glucose metabolism; insight; mutant; novel; object recognition; promoter; protein function; repaired; research study; response; transcription factor

 DESCRIPTION (provided by applicant): This study will explore the hypothesis that hyperactivation of the cAMP response element-binding protein (CREB)-a transcription factor with diverse functions in the central nervous system and metabolic regulation-contributes to mitochondrial defects and pathologic reactive oxygen species (ROS) formation in ataxia-telangiectasia (A-T), a neurodegenerative disease caused by mutations in the ATM gene. ATM encodes a protein kinase with instrumental roles in the signaling and repair of DNA double-strand breaks, a highly carcinogenic form of DNA damage. ATM is also thought to play an important role in mitochondrial homeostasis and suppression of toxic ROS; however this aspect of ATM function is poorly understood. In published work we showed that ATM phosphorylates CREB on a conserved cluster of Ser residues that attenuates CREB transactivation potential in response to DNA damage and other forms of cellular stress. Of importance to this proposal, an independent study recently showed that the nuclear corepressor NCoR1 represses a large number of CREB target genes with mitochondrial function. Here we will explore the idea that ATM, CREB, and NCoR1 function in a common pathway to critically attenuate mitochondrial function and ROS generation in response to DNA damage and oxidative stress. Specifically, we propose that ATM-mediated phosphorylation of CREB recruits NCoR1 to silence mitochondrial target genes. The relevance of this hypothesis for A-T is that defective CREB phosphorylation may engender mitochondrial defects and oxidative stress that contribute to neuronal injury. We will test these ideas using a combination of biochemical and genetic approaches, including the use of gene-targeted mice expressing a mutant CREB allele (CREBS111A) refractory to phosphorylation by ATM. CREBS111A mice exhibit metabolic abnormalities and alterations in CREB- mediated gene expression, and fibroblasts and neurons from these mice will be used to explore the mechanisms of NCoR1-dependent CREB attenuation. In summary, the proposed work will define the impact of ATM-mediated CREB phosphorylation on transcriptional regulation and mitochondrial homeostasis. Results from this work may provide important new insights into how loss of ATM leads pathologic oxidative stress in A-T. The Specific Aims of the proposal are to: i) Assess ROS, mitochondrial dynamics, and cerebellar gene expression in CREBS111A mice; and ii) Define signal and phosphorylation-dependent functional relationships between CREB and NCoR1.

 描述(申请人提供)：这项研究将探索一种假说，即cAMP反应元件结合蛋白(CREB)-一种在中枢神经系统和代谢调节中具有不同功能的转录因子-的过度激活导致了线粒体缺陷和病理性活性氧物种(ROS)的形成，这是一种由ATM基因突变引起的神经退行性疾病。ATM编码一种蛋白激酶，在DNA双链断裂的信号和修复中发挥重要作用，双链断裂是一种高度致癌的DNA损伤形式。ATM也被认为在线粒体动态平衡和抑制毒性ROS方面发挥着重要作用；然而，人们对ATM这一方面的功能知之甚少。在已发表的工作中，我们表明ATM使CREB在保守的Ser残基簇上磷酸化，从而减弱CREB对DNA损伤和其他形式的细胞应激的反式激活潜力。最近的一项独立研究表明，核辅阻遏子NCoR1抑制了大量具有线粒体功能的CREB靶基因，这对这一提议很重要。在这里，我们将探讨ATM、CREB和NCoR1在一个共同的途径中发挥作用，以严重削弱线粒体功能和ROS的产生，以响应DNA损伤和氧化应激。具体地说，我们认为ATM介导的CREB的磷酸化招募NCoR1来沉默线粒体靶基因。这一假说与A-T的相关性在于，CREB磷酸化缺陷可能会导致线粒体缺陷和氧化应激，从而导致神经元损伤。我们将使用生化和遗传方法的组合来测试这些想法，包括使用表达突变的CREB等位基因(CREBS111a)的基因靶向小鼠，该突变的CREB等位基因对ATM的磷酸化不起作用。CREBS111A小鼠表现出代谢异常和CREB介导的基因表达的改变，这些小鼠的成纤维细胞和神经元将被用来探索NCoR1依赖的CREB衰减的机制。综上所述，拟议的工作将定义ATM介导的CREB磷酸化对转录调控和线粒体动态平衡的影响。这项工作的结果可能为ATM丢失如何导致A-T的病理性氧化应激提供重要的新见解。该提案的具体目的是：i)评估CREBS111a小鼠的ROS、线粒体动力学和小脑基因表达；以及ii)确定CREB和NCoR1之间依赖信号和磷酸化的功能关系。