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Factors controlling metabolic flux in the liver by NMR isotopomer analysis

通过核磁共振同位素分析控制肝脏代谢通量的因素

基本信息

批准号：
8440067
负责人：
Shawn C Burgess
金额：
$ 34.58万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-02-01 至 2016-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8440067
关键词：
Acute Address Anabolism Animal Model Cell Respiration Charge Citric Acid Cycle Dietary Intervention Etiology Evaluation Excision Fatty Liver Fumarate Hydratase Fumarate Hydratase Deficiency Funding Gene Expression Genetic Genetic Suppression Gluconeogenesis Glucose Hepatic Human Hyperglycemia Hyperlipidemia Inflammation Inflammatory Inflammatory Response Insulin Insulin Resistance Knowledge Link Lipids Liver Liver diseases Marshal Mediating Mediator of activation protein Metabolic Metabolic Control Metabolic Pathway Metabolism Methods Mitochondria Molecular Mus NADH Non-Insulin-Dependent Diabetes Mellitus Outcome Oxidative Stress Pathogenesis Pathologic Pathology Pathway interactions Phosphoenolpyruvate Carboxylase Play Process Production Regulation Role Secondary to Signal Transduction Testing Tracer Tricarboxylic Acids Up-Regulation base biological adaptation to stress cofactor gene therapy improved in vivo innovation insulin sensitivity insulin signaling lipid biosynthesis liver metabolism new therapeutic target non-alcoholic fatty liver novel oxidation prevent public health relevance response sensor transcription factor

项目摘要

DESCRIPTION (provided by applicant): This project investigates the regulation of metabolic flux in the hepatic tricarboxylic acid (TCA cycle) and its role in hepatic insulin resistance. The proposal follows up on key findings in the last funding cycle which indicate that anaplerotic/cataplerotic biosynthetic flux from the TCA cycle and oxidative flux of the TCA cycle are reciprocally regulated and that these pathways are elevated during hepatic insulin resistance. These findings challenge the role of impaired oxidative metabolism as an instigator of hepatic insulin resistance. Thus, we propose a novel hypothesis that elevated hepatic TCA cycle flux is a principal metabolic mediator of pathologies of hepatic insulin resistance by potentiating biosynthetic flux (e.g. gluconeogenesis) and oxidative stress. We test this hypothesis using conditional KO mice, state of the art 13C and 2H tracer based NMR and MS/MS isotopomer methods to evaluate hepatic metabolic fluxes of glucose, lipid and TCA cycle metabolism, and standard evaluation of signaling, gene expression and insulin sensitivity. The first aim is to test whether insulin action mediates dys/regulation of TCA cycle fluxes. We determine if acute genetic excision of insulin signaling recapitulates or exasperates elevated TCA cycle flux in HFD mice and whether acute deletion of FOXo1 ameliorates TCA cycle flux and oxidative stress during a HFD. Since these pathways are also subject indirect upregulation by substrate delivery during insulin resistance, the second aim is to determine the mechanism of co-regulation between cataplerotic biosynthesis and oxidative TCA cycle flux. While the acute regulation of these pathways by ATP, NADH and allosteric regulators are known, we will test whether AMPK and Sirt3 act as acute molecular regulators of flux through TCA cycle pathways. Finally, if elevated TCA cycle flux potentiates metabolic pathologies of hepatic insulin resistance, then suppressing TCA cycle pathways should prevent the onset of hepatic complications. Thus, the third aim is to determine if genetic suppression of the cataplerotic or the oxidative span of the TCA cycle results in improved metabolic, oxidative stress and inflammatory response to insulin resistance.

描述（由申请人提供）：本项目研究肝三羧酸（TCA循环）中代谢通量的调节及其在肝胰岛素抵抗中的作用。该提案跟进了上一个供资周期的关键发现，这些发现表明，来自TCA循环的回补/分解生物合成通量和TCA循环的氧化通量受到严格调节，并且这些途径在肝脏胰岛素抵抗期间升高。这些发现挑战了氧化代谢受损作为肝脏胰岛素抵抗的煽动者的作用。因此，我们提出了一个新的假设，即肝TCA循环通量升高是通过增强生物合成通量（例如，代谢产物生成）和氧化应激导致肝胰岛素抵抗的病理学的主要代谢介质。我们使用条件性KO小鼠、基于最新技术水平的13 C和2 H示踪剂的NMR和MS/MS同位素异构体方法来测试该假设，以评估葡萄糖、脂质和TCA循环代谢的肝代谢通量，以及信号传导、基因表达和胰岛素敏感性的标准评估。第一个目的是测试胰岛素作用是否介导TCA循环通量的dys/调节。我们确定是否急性基因切除胰岛素信号重现或加剧HFD小鼠的TCA循环流量升高，以及急性缺失FOXo 1是否改善HFD期间的TCA循环流量和氧化应激。由于这些途径在胰岛素抵抗期间也受到底物递送的间接上调，因此第二个目的是确定cataplerotic生物合成和氧化TCA循环通量之间的共调节机制。虽然ATP，NADH和变构调节剂对这些途径的急性调节是已知的，但我们将测试AMPK和Sirt 3是否作为通过TCA循环途径的通量的急性分子调节剂。最后，如果升高的TCA循环通量加强肝脏胰岛素抵抗的代谢病理，那么抑制TCA循环途径应该可以预防肝脏并发症的发生。因此，第三个目的是确定TCA循环的cataplerotic或氧化跨度的遗传抑制是否导致对胰岛素抵抗的代谢、氧化应激和炎症反应的改善。