DNA Repair Deficiency Associated with Obesity and the Metabolic Syndrome

与肥胖和代谢综合征相关的 DNA 修复缺陷

• 批准号: 7728334
• 负责人: R. Stephen Lloyd
• 金额: $ 36.57万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-20 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7728334
• 关键词: A Mouse; Adult; Affect; American; Animals; Backcrossings; Base Excision Repairs; Biological; Biological Assay; Body Composition; Cardiovascular Diseases; Cell Extracts; Cell Line; Cell Nucleus; Cell Survival; Cells; Circadian Rhythms; Complement; DNA; DNA Damage; DNA Repair; DNA Repair Disorder; DNA biosynthesis; DNA glycosylase; DNA lesion; Data; Diet; Disease; Disease Progression; Dyslipidemias; Eating; Embryo; Enzymes; Epidemic; Etiology; Evaluation; Exhibits; Experimental Designs; Exposure to; Fat-Restricted Diet; Fatty Liver; Fatty acid glycerol esters; Female; Fibroblasts; Gene Expression; Gene Mutation; Generations; Genes; Genetic Transcription; Genome; Hepatic; Home environment; Homeostasis; Human; Hyperinsulinism; Hypertension; Insulin Resistance; Investigation; Knock-out; Knockout Mice; Lead; Lesion; Lipids; Liver diseases; Lung; Magnetic Resonance Imaging; Malignant Neoplasms; Malignant neoplasm of liver; Measures; Metabolic; Metabolic syndrome; Mitochondria; Mitochondrial DNA; Molecular; Monitor; Morbid Obesity; Movement; Mus; Mutagenesis; Nitric Oxide; Non-Insulin-Dependent Diabetes Mellitus; Nonesterified Fatty Acids; Nuclear; Nucleic Acids; OGG1 gene; Obesity; Organism; Outcome; Oxidative Stress; Phenotype; Physiological; Production; Protein Isoforms; Proteins; Purines; Reactive Oxygen Species; Relative (related person); Role; Running; Shuttle Vectors; Site; Stress; Symptoms; System; Techniques; Testing; Transcript; Transgenic Mice; Variant; Vitamin K 3; Weight; base; carcinogenesis; cellular targeting; comparative; human disease; killings; lipid metabolism; liquid chromatography mass spectrometry; male; middle age; mitochondrial dysfunction; mouse model; oxidant stress; prevent; public health relevance; purine; repaired; response

DESCRIPTION (provided by applicant): Exposure to oxidative stress conditions and the generation of excessive reactive oxygen species (ROS) are generally hypothesized to be a common causative factor in the etiology of several human diseases including, but not limited to, fatty liver disease, dyslipidemia, insulin-resistant type 2 diabetes, cardiovascular disease/hypertension, and obesity (collectively known as Metabolic Syndrome). Although it is well established that lipids, proteins and nucleic acids are critical cellular targets for endogenously and exogenously produced ROS, until recently, deficiencies in repair of ROS-induced DNA base damage had not been considered to be key in the aforementioned diseases, while being considered central to carcinogenesis. However, two knockout mouse models (neil1 and ogg1) have been created in which the initiation of base excision repair of oxidatively-damaged DNA is defective, and in both models, mice develop subsets of symptoms consistent with Metabolic Syndrome. Disease manifestations in the neil1 knockout mice may include obesity, fatty liver disease, dyslipidemia and hyperinsulinemia, with male knockouts much more severely affected than females. In addition, analyses of nuclear DNAs isolated from these mice reveal the accumulation of high levels of ROS-damaged bases and mitochondrial DNAs (mtDNA) show both increased steady-state base damage and large deletions relative to control littermates. Since it known that excessive oxidative stress can induce symptoms of Metabolic Syndrome in repair-proficient organisms, it is hypothesized that the loss of NEIL1 or OGG1 lowers the threshold at which oxidatively stress-induced disease is manifested. In the absence of repair, the progressive accumulation of compromised mtDNA genomes leads to deficiencies in energy production, as well as alterations in free fatty acid and lipid metabolism. In order to test this hypothesis, multiple physiological parameters will be evaluated for changes in neil1-/-, ogg1-/- and neil1-/-ogg1-/- mice and their wild-type littermates during pro-oxidant challenges versus control conditions. These data will be correlated with rates of pathological changes and mitochondrial and nuclear DNA damage accumulation as measured by GC/MS and quantitative PCR. These analyses will be complemented by examining the role of NEIL1 in the modulation of survival, mutagenesis, and mitochondrial function in response to oxidative or nitric oxide stress conditions. Further, since repair of mtDNA is hypothesized to be critical in maintaining metabolic homeostasis, experimental designs are proposed to establish intracellular distribution of various NEIL1 isoforms and determine the biological consequences of expressing nuclear or mitochondrially-targeted forms of these enzymes in neil1-/- cells. PUBLIC HEALTH RELEVANCE: The growing epidemic of human obesity is currently estimated to affect over 60 million adult Americans, with secondary consequences including, but not limited to, fatty liver disease, cardiovascular disease, and insulin resistance/type 2 diabetes, collectively known as the Metabolic Syndrome. A potential underlying molecular mechanism for these diseases is suggested by the study of DNA repair-deficient mouse models that lack oxidative DNA base damage repair and exhibit many of the defining hallmarks of the Metabolic Syndrome: severe obesity, fatty liver disease, dyslipidemia, and insulin resistance. These investigations will examine the role of reduced DNA repair in the onset and progression of these diseases.

描述（由申请人提供）：一般认为，暴露于氧化应激条件和产生过多的活性氧（ROS）是多种人类疾病病因学中的常见致病因素，包括但不限于脂肪肝疾病、血脂异常、胰岛素抵抗2型糖尿病、心血管疾病/高血压和肥胖（统称为代谢综合征）。尽管众所周知，脂质、蛋白质和核酸是内源性和外源性产生的 ROS 的关键细胞靶标，但直到最近，ROS 诱导的 DNA 碱基损伤修复缺陷还没有被认为是上述疾病的关键，而被认为是致癌的核心。然而，已经创建了两种基因敲除小鼠模型（neil1 和 ogg1），其中氧化损伤 DNA 的碱基切除修复启动有缺陷，并且在这两种模型中，小鼠都会出现与代谢综合征一致的症状子集。 neil1基因敲除小鼠的疾病表现可能包括肥胖、脂肪肝、血脂异常和高胰岛素血症，其中雄性基因敲除小鼠受到的影响比雌性严重得多。此外，对从这些小鼠中分离出的核 DNA 的分析表明，与对照同窝小鼠相比，ROS 损伤碱基的高水平积累和线粒体 DNA (mtDNA) 均显示出稳态碱基损伤增加和大量缺失。由于已知过度的氧化应激可在修复能力强的生物体中诱发代谢综合征的症状，因此推测 NEIL1 或 OGG1 的缺失会降低氧化应激诱发的疾病出现的阈值。在缺乏修复的情况下，受损线粒体DNA基因组的逐渐积累会导致能量产生不足，以及游离脂肪酸和脂质代谢的改变。为了检验这一假设，将评估在促氧化剂挑战期间与对照条件下 neil1-/-、ogg1-/- 和 neil1-/-ogg1-/- 小鼠及其野生型同窝小鼠的多个生理参数的变化。这些数据将与通过 GC/MS 和定量 PCR 测量的病理变化率以及线粒体和核 DNA 损伤积累相关。这些分析将通过检查 NEIL1 在响应氧化或一氧化氮应激条件而调节生存、诱变和线粒体功能中的作用来补充。此外，由于假设线粒体DNA的修复对于维持代谢稳态至关重要，因此提出了实验设计来建立各种NEIL1亚型的细胞内分布，并确定在neil1-/-细胞中表达这些酶的核或线粒体靶向形式的生物学后果。公共健康相关性：目前，人类肥胖症日益流行，估计影响超过 6000 万成年美国人，其继发后果包括但不限于脂肪肝疾病、心血管疾病和胰岛素抵抗/2 型糖尿病（统称为代谢综合征）。对 DNA 修复缺陷小鼠模型的研究表明了这些疾病的潜在分子机制，这些小鼠模型缺乏氧化 DNA 碱基损伤修复，并表现出代谢综合征的许多定义特征：严重肥胖、脂肪肝疾病、血脂异常和胰岛素抵抗。这些研究将探讨 DNA 修复减少在这些疾病的发生和进展中的作用。