Regulation of insulin signaling and sensitivity by the xenobiotic metabolizing enzyme NQO1

异生物质代谢酶 NQO1 对胰岛素信号传导和敏感性的调节

• 批准号: 9309955
• 负责人: Kristofer S. Fritz
• 金额: $ 38.88万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9309955
• 关键词: Acetylation; Adipocytes; Adipose tissue; Animals; Antibodies; Binding; Biochemical; Biogenesis; Biological; Caloric Restriction; Cardiovascular system; Cell physiology; Complex; Data; Deacetylation; Diabetes Mellitus; Diabetic Nephropathy; Diet; Docking; Dose; Dyslipidemias; Electrophoresis; Enzymes; Epidemic; Generations; Genes; Genetic Polymorphism; Glucose; Glucose Intolerance; High Fat Diet; Human; Hypertension; IRS1 gene; Impairment; Insulin; Insulin Receptor; Insulin Resistance; Mediating; Metabolic; Metabolic syndrome; Mitochondria; Molecular Conformation; Morbidity - disease rate; Mus; Muscle Cells; Mutation; Mutation Analysis; NADH; NQO1 gene; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Oxidation-Reduction; Oxidative Phosphorylation; Pathology; Pharmacology; Phenotype; Phosphorylation; Phosphotransferases; Physical activity; Physiological; Play; Proteins; Proto-Oncogene Proteins c-akt; Regulation; Role; SIRT1 gene; Scaffolding Protein; Serine; Signal Transduction; Signaling Molecule; Signaling Protein; Sirtuins; Skeletal Muscle; Structure; Testing; Transgenic Mice; Transgenic Organisms; Tyrosine Phosphorylation; Work; Xenobiotics; base; cardiovascular risk factor; global health; glucose uptake; in vivo; inhibitor/antagonist; insulin sensitivity; insulin signaling; knock-down; knockout animal; mortality; mutant; novel; overexpression; protective effect; protein complex; pyridine nucleotide; response; scaffold; skills

Metabolic syndrome comprises a group of cardiovascular risk factors including obesity, high blood pressure, glucose intolerance and dyslipidemia whose underlying pathology is related to insulin resistance. We have shown that the xenobiotic-metabolizing enzyme NQO1 is critical to insulin sensitivity and protection from diet-induced morbidities. Increasing NQO1 expression using NQO1 transgenic mice protects against the negative biochemical and physiological effects of a high fat diet and confers increased insulin sensitivity. Pharmacological inhibition of NQO1 using selective mechanism-based inhibitors led to a severe impairment in insulin sensitivity in mice. NQO1 knockout animals are insulin-insensitive resulting in a diabetes-like phenotype and a null NQO1 polymorphism is associated with metabolic syndrome phenotypes in humans. Our data shows that NQO1 is required for activation of AKT by enabling its insulin-inducible interaction with the protein complex TORC 2 allowing AKT serine phosphorylation and full glucose utilization. Insulin administration led to a rapid and marked increase in NQO1 tyrosine phosphorylation by the insulin receptor and mutational analysis suggests that phosphorylation leads to major changes in NQO1 functionality. Conformation-dependent antibodies and electrophoresis also indicated marked changes in NQO1 conformation as a result of either altered pyridine nucleotide redox ratios or addition of insulin. Based on the cellular functions of NQO1, we will test 3 biologically plausible mechanisms underlying the observed role of NQO1 in insulin signaling and protection against metabolic syndrome phenotypes. 1) NQO1 modulates insulin-dependent signaling by protein scaffolding. We will test the hypothesis that the observed effects of NQO1 on insulin sensitivity are modulated by a change in NQO1 conformation induced either by alterations in pyridine nucleotide levels or by phosphorylation of NQO1 by the insulin receptor, facilitating optimal association of AKT and Rictor and downstream insulin signaling; 2) NQO1 generates NAD+ for optimal SIRT activity. Deacetylation via SIRTs is critical in insulin signaling and NQO1 can rapidly generate high levels of NAD+ for optimal sirtuin activity; 3) Stabilization of critical metabolic regulators. The key metabolic regulator PGC1α is protected against proteasomal degradation by NQO1. Both PGC1α and AMPK influence mitochondrial oxidative phosphorylation and biogenesis and protect against metabolic syndrome. We will therefore define whether NQO1 influences metabolic syndrome by modulation of PGC1α and AMPK levels. Our working hypothesis is that NQO1 plays a critical role in insulin sensitivity and protection against metabolic syndrome phenotypes but the critical question that remains to be answered is the mechanism(s) underlying the beneficial effects of NQO1.

代谢综合征由一组心血管危险因素组成，包括肥胖、高血压、血糖 不耐受和血脂异常，其潜在病理学与胰岛素抵抗有关。 异生物质代谢酶 NQO1 对于胰岛素敏感性和预防饮食引起的疾病至关重要。 使用 NQO1 转基因小鼠增加 NQO1 表达可防止负面生化和 高脂肪饮食的生理效应，并增加 NQO1 的药理学抑制作用。 使用选择性机制抑制剂导致小鼠 NQO1 胰岛素敏感性严重受损。 基因敲除动物对胰岛素不敏感，导致糖尿病样表型，并且 NQO1 多态性无效 与人类代谢综合征表型相关。我们的数据表明，NQO1 是激活 AKT 通过与蛋白质复合物 TORC 2 发生胰岛素诱导相互作用，从而允许 AKT 丝氨酸 磷酸化和完全葡萄糖利用导致 NQO1 快速显着增加。 胰岛素受体的酪氨酸磷酸化和突变分析表明磷酸化会导致主要 NQO1 功能的变化也显示出构象依赖性抗体和电泳的显着变化。 由于改变吡啶核苷酸氧化还原比或添加胰岛素而导致 NQO1 构象发生变化。 基于 NQO1 的细胞功能，我们将测试观察到的 3 种生物学上合理的机制 NQO1 在胰岛素信号传导和代谢综合征表型保护中的作用 1) NQO1 调节。 我们将测试 NQO1 观察到的影响的假设。 对胰岛素敏感性的影响是通过吡啶的改变引起的 NQO1 构象的变化来调节的 核苷酸水平或通过胰岛素受体磷酸化 NQO1，促进 AKT 的最佳结合 Rictor 和下游胰岛素信号转导；2) NQO1 产生 NAD+ 以实现最佳的 SIRT 活性。 通过 SIRT 在胰岛素信号传导中至关重要，NQO1 可以快速生成高水平的 NAD+，以实现最佳的 Sirtuin 3) 关键代谢调节因子 PGC1α 的稳定性受到保护。 NQO1 的蛋白酶体降解影响线粒体氧化磷酸化和 因此，我们将定义 NQO1 是否影响代谢。 调节 PGC1α 和 AMPK 水平引起的综合征。 我们的工作假设是 NQO1 在胰岛素敏感性和代谢保护中发挥着关键作用 综合征表型，但仍有待回答的关键问题是其背后的机制 NQO1 的有益作用。