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: 8249438
• 负责人: R. Stephen Lloyd
• 金额: $ 32.83万
• 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 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8249438
• 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; Health; Hepatic; Home environment; Homeostasis; Human; Hyperinsulinism; Hypertension; Insulin Resistance; Investigation; Knock-out; Knockout Mice; Lead; Lesion; Lipids; Liver diseases; Magnetic Resonance Imaging; Malignant Neoplasms; Malignant neoplasm of liver; Malignant neoplasm of lung; 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; 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）：暴露于氧化应激条件和过量活性氧（ROS）的产生通常被假设为几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、胰岛素抵抗型2型糖尿病、心血管疾病/高血压和肥胖（统称为代谢综合征）。虽然脂质、蛋白质和核酸是内源性和外源性活性氧的关键细胞靶点，但直到最近，活性氧诱导的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，已经建立了两种敲除小鼠模型（neil1和ogg1），其中氧化损伤DNA的碱基切除修复启动存在缺陷，并且在这两种模型中，小鼠出现与代谢综合征一致的症状亚群。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，雄性基因敲除小鼠受到的影响要比雌性严重得多。此外，对从这些小鼠中分离的核dna的分析显示，高水平的ros损伤碱基和线粒体dna （mtDNA）的积累表明，与对照组相比，稳态碱基损伤和大量缺失都增加了。由于已知过度氧化应激可在修复能力强的生物体中诱导代谢综合征症状，因此假设NEIL1或OGG1的缺失降低了氧化应激诱导疾病表现的阈值。在缺乏修复的情况下，受损mtDNA基因组的逐渐积累导致能量产生不足，以及游离脂肪酸和脂质代谢的改变。为了验证这一假设，将评估多种生理参数在促氧化剂刺激和对照条件下neil1-/-、ogg1-/-和neil1-/-ogg1-/-小鼠及其野生型幼崽的变化。这些数据将通过GC/MS和定量PCR测量与病理改变率和线粒体和核DNA损伤积累相关。这些分析将通过检查NEIL1在氧化或一氧化氮应激条件下对生存、诱变和线粒体功能的调节中的作用来补充。此外，由于mtDNA的修复被假设为维持代谢稳态的关键，因此提出了实验设计来建立各种NEIL1异构体的细胞内分布，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。公共卫生相关性：目前估计，人类肥胖的日益流行影响了6000多万成年美国人，其继发性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。DNA修复缺陷小鼠模型缺乏氧化性DNA碱基损伤修复，并表现出许多代谢综合征的典型特征：严重肥胖、脂肪肝、血脂异常和胰岛素抵抗，这一研究提示了这些疾病的潜在分子机制。这些研究将检查DNA修复减少在这些疾病的发生和进展中的作用。