Beta-Oxidation and Susceptibility to Fatty Liver Disease

β-氧化和对脂肪肝疾病的易感性

• 批准号: 7484072
• 负责人: JAMAL A IBDAH
• 金额: $ 26.25万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7484072
• 关键词: Acids; Affect; Age; Aging; Cessation of life; Cirrhosis; Data; Defect; Development; Euglycemic Clamping; Fatty Acids; Fatty Liver; Gene Proteins; Generations; Genes; Glucose Clamp; Goals; Hepatic; Hepatocyte; Individual; Inflammation; Inflammatory; Inflammatory Response; Injury; Injury to Liver; Insulin Receptor; Insulin Resistance; Liver; Liver diseases; Measurement; Measures; Mitochondria; Mitochondrial Proteins; Modeling; Molecular Profiling; Multienzyme Complexes; Mus; Muscle; NF-kappaB-inducing kinase; Natural Immunity; Neonatal; Nonesterified Fatty Acids; Numbers; Oxidative Stress; Pathogenesis; Pathway interactions; Patients; Peripheral; Phosphatidylinositols; Phosphorylation; Phosphotransferases; Population; Predisposition; Prevention; Protein Overexpression; Proteins; Reactive Oxygen Species; Relative (related person); Research Personnel; Role; Salicylic Acid; Salicylic Acids; Signaling Molecule; Superoxide Dismutase; Superoxides; Testing; Tissues; Transgenic Mice; Transgenic Organisms; Wild Type Mouse; basal insulin; cytokine; fatty acid oxidation; glucose production; glucose uptake; human SOD2 protein; inhibitor/antagonist; insulin receptor serine kinase; kinase inhibitor; long chain fatty acid; mouse model; non-alcoholic fatty liver; nonalcoholic steatohepatitis; oxidation; prevent; programs; tempol

DESCRIPTION (provided by applicant): Nonalcoholic fatty liver disease (NAFLD) is considered the most common form of liver disease, yet its underlying pathogenesis is poorly understood. Evidence suggests that pathogenesis of NAFLD involves increased levels of free fatty acids, activation of innate immunity genes, and insulin resistance. Although mitochondrial beta-oxidation is the major pathway for oxidation of fatty acids, its role in the pathogenesis of NAFLD remains unknown. We generated a mouse model for mitochondrial trifunctional protein (MTP) that catalyzes the last 3 steps in long chain beta-oxidation. Homozygous mice suffer neonatal death. Our preliminary data document that aging heterozygous mice develop hepatic steatosis associated with oxidative stress and insulin resistance. This proposal uses this murine model to investigate mechanisms underlying NAFLD. Our central hypothesis is that heterozygosity for MTP causes insulin resistance and liver injury associated with hepatic steatosis by increasing cellular oxidative stress. We propose studies towards the following specific aims: 1) To test that heterozygosity for an MTP defect results in an age-associated steatosis with superoxide overproduction leading to activation of the inhibitor KB kinase (IKK), insulin resistance, and liver injury, and to test that prevention of oxidative stress prevents both insulin resistance and hepatic injury in the heterozygous mice. Studies will be conducted to determine the temporal relationship between oxidative stress and hepatic steatosis/injury, insulin resistance, and IKK. We also propose interventional studies to prevent oxidative stress by either scavenging superoxide species using Tempol or by crossing our MTP heterozygous mice to transgenic mice overexpressing superoxide dismutases. 2. To test that activation of IKK causes a) NFkB activation leading to a low-grade inflammation and hepatic injury and b) impaired IRS- dependent activation of the Principal Investigator3K-Akt pathway leading to insulin resistance in mice heterozygous for an MTP defect and to test that inhibition of IKK reverses insulin resistance and hepatic injury. For this, we will measure the content and activation status of IKK and NFkB in both liver and muscle and assess the expression profile of proinflammatory cytokines in liver. We also propose to measure basal and insulin- stimulated contents and phosphorylation/activation status of Akt and the upstream signaling molecules Principal Investigator3K and IRS-1/2 in both liver and muscle. The relative contribution of hepatic and peripheral insulin resistance to whole body insulin resistance will be assessed using hyperinsulinemic-euglycemic clamp. To test the causative relationship between IKK, insulin resistance, and hepatic inflammatory response, mice will be treated with acetyl salicylic acid (ASA), a known IKK inhibitor and then NFkB activation, hepatic inflammation, insulin resistance, and activation status of the Principal Investigator3K/Akt pathway will be evaluated.

描述（由申请人提供）：非酒精性脂肪肝疾病（NAFLD）被认为是肝病最常见的形式，但其潜在的发病机理知之甚少。有证据表明，NAFLD的发病机理涉及自由脂肪酸的水平增加，先天免疫基因的激活和胰岛素抵抗。尽管线粒体β-氧化是脂肪酸氧化的主要途径，但其在NAFLD发病机理中的作用仍然未知。我们生成了一种用于线粒体三官能蛋白（MTP）的小鼠模型，该蛋白（MTP）催化了长链β-氧化的最后3个步骤。纯合小鼠遭受新生儿死亡。我们的初步数据证明，衰老的杂合小鼠会发展与氧化应激和胰岛素抵抗相关的肝脂肪变性。该提案使用该鼠模型来研究NAFLD基础的机制。我们的中心假设是，MTP的杂合性通过增加细胞氧化应激而引起与肝脂肪变性相关的胰岛素抵抗和肝损伤。我们提出针对以下具体目的的研究：1）测试MTP缺陷的杂合性导致与超氧化物相关的脂肪变性，超氧化物产生过量产生，从而激活抑制剂KB激酶（IKK），胰岛素抵抗，胰岛素抵抗和肝脏损伤，并测试氧化度损伤的胰岛素耐药性和Hepation hepation hepation hepation hepation hepation heptic hepation heptic hep hep hep hep hep hep hep损伤。将进行研究以确定氧化应激与肝脂肪变性/损伤，胰岛素抵抗和IKK之间的时间关系。我们还提出了介入的研究，以防止使用tempol清除超氧化物物种，或者通过将我们的MTP杂合小鼠越过过表达超氧化物歧化酶的转基因小鼠。 2. To test that activation of IKK causes a) NFkB activation leading to a low-grade inflammation and hepatic injury and b) impaired IRS- dependent activation of the Principal Investigator3K-Akt pathway leading to insulin resistance in mice heterozygous for an MTP defect and to test that inhibition of IKK reverses insulin resistance and hepatic injury.为此，我们将测量肝脏和肌肉中IKK和NFKB的含量和激活状态，并评估肝脏中促炎细胞因子的表达谱。我们还建议在肝脏和肌肉中测量AKT和上游信号分子的基础和胰岛素刺激含量以及AKT和上游信号分子的磷酸化/激活状态。肝和周围胰岛素抵抗对全身胰岛素耐药性的相对贡献将使用高胰岛素血糖夹评估。为了测试IKK，胰岛素抵抗和肝炎症反应之间的致病关系，将用乙酰水杨酸（ASA），已知的IKK抑制剂，然后将NFKB激活，肝炎症，胰岛素耐药性和胰岛素耐药性和主要研究员的激活状态对小鼠进行治疗。