NAD+ and metabolic flexibility

NAD 和代谢灵活性

• 批准号: 10316981
• 负责人: Samuel Klein
• 金额: $ 39.38万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-11 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10316981
• 关键词: Acetylation; Adipocytes; Adipose tissue; Adrenergic Agents; Anabolism; Biology; Biopsy Specimen; Blood specimen; Body Weight decreased; Calories; Cell Culture System; Clinical; Coenzymes; Data; Dependovirus; Diet; Energy Metabolism; Enhancers; Enzymes; Exercise; Foundations; Functional disorder; Funding; Genetic; Genetically Engineered Mouse; Grant; High Fat Diet; Human; Impairment; In Vitro; Insulin Resistance; Knockout Mice; Life Style Modification; Link; Liver; Lysine; Mediating; Mediator of activation protein; Metabolic; Metabolic Pathway; Metabolism; Mitochondria; Molecular; Mus; Nicotinamide Mononucleotide; Nicotinamide adenine dinucleotide; Non-Insulin-Dependent Diabetes Mellitus; Obese Mice; Obesity; Overweight; Oxidation-Reduction; PPARG gene; Persons; Pharmacology; Physiological; Placebos; Prediabetes syndrome; Risk; Rodent; Series; Sirtuins; Skeletal Muscle; Supervision; Supplementation; System; Tamoxifen; Testing; Thermogenesis; Tissues; Visceral; base; caveolin 1; clinically relevant; dietary restriction; exercise training; feeding; flexibility; glucose metabolism; improved; indexing; insight; insulin sensitivity; insulin signaling; mouse model; nicotinamide phosphoribosyltransferase; non-alcoholic fatty liver disease; novel; obesity treatment; overexpression; response; therapeutic target

Obesity is associated with an increased risk of serious metabolic abnormalities, such as type 2 diabetes, insulin resistance, and nonalcoholic fatty liver disease (NAFLD). Data obtained from studies conducted in humans and rodents have suggested that “metabolic inflexibility” is critically involved in the pathophysiology of such metabolic abnormalities. The mechanism(s) responsible for obesity-induced metabolic inflexibility is not clear but could involve altered metabolic activity in white adipose tissue (WAT). In the current funding cycle of this grant, we have focused on studying adipose tissue NAD+ biology and conducted a series of studies that demonstrate the causal relationship between defective WAT NAD+ metabolism and metabolic inflexibility. We found: 1) loss of NAMPT, a key NAD+ biosynthetic enzyme, impairs cellular insulin signaling, mitochondrial function, and adrenergic-stimulated lipolytic activity in WAT; 2) adipocyte-specific Nampt knockout (ANKO) mice have multi-organ (skeletal muscle, liver, WAT) insulin resistance, hypoadiponectinemia, impaired adaptive thermogenesis and whole-body energy metabolism, and impaired fuel selection to hypercaloric and hypocaloric challenges; 3) a novel molecular link between NAD+ metabolism and Caveolin-1 (CAV1), a key regulator of whole-body metabolic flexibility; 4) dietary restriction and exercise, well-known enhancers of metabolic flexibility, stimulate NAMPT-mediated NAD+ biosynthesis in WAT; and 5) consistent with our rodent data, people with obesity have decreases in WAT NAMPT expression and NAD+ concentration. Based on these findings, this renewal application will test the hypotheses that NAMPT-mediated NAD+ biosynthesis regulates CAV1 and mitochondrial function in WAT, key effectors of metabolic flexibility and glucose metabolism, and that defective WAT NAD+ metabolism is a novel mechanism and therapeutic target for obesity-induced metabolic inflexibility. In Aim 1, we propose to generate two novel mouse models, mice overexpressing NAMPT selectively in visceral WAT (using the novel AAV system) and tamoxifen-inducible ANKO (iANKO) mice, and evaluate metabolic responses to high-fat diet feeding and lifestyle modification (dietary restriction, exercise). In Aim 2, we propose to use in vitro systems and explore four mechanisms (lysine acetylation of CAV1, PPARG, sirtuins, and redox metabolism) that link NAD+ metabolism with CAV1 and mitochondrial function. Finally, in Aim 3, we propose to determine the potential clinical relevance of the studies we conducted in the mouse model (Aim 1) and cell culture systems (Aim 2). Specifically, we will evaluate the effects of two potential “NAD+ enhancers”, namely lifestyle modification (low- calorie diet ± supervised exercise training) and nicotinamide mononucleotide (NMN) supplementation (250 mg/day, 8 weeks), on WAT NAD+ metabolism, CAV1, and mitochondrial biology in overweight people. The anticipated results obtained from this proposal will provide novel insight into the importance of adipose tissue NAD+ biology in regulating metabolic flexibility and glucose metabolism.

肥胖与严重代谢异常的风险增加有关，如2型糖尿病，胰岛素抵抗和非酒精性脂肪肝（NAFLD）。从人类和啮齿动物中进行的研究中获得的数据表明，“代谢不稳定性”在这种代谢异常的病理生理学中至关重要。肥胖诱导代谢紊乱的机制尚不清楚，但可能涉及白色脂肪组织（WAT）中代谢活性的改变。在该资助的当前资助周期中，我们专注于研究脂肪组织NAD+生物学，并进行了一系列研究，证明了WAT NAD+代谢缺陷与代谢能力之间的因果关系。我们发现：1）NAMPT（一种关键的NAD+生物合成酶）的丧失损害了WAT中的细胞胰岛素信号传导、线粒体功能和肾上腺素能刺激的脂解活性; 2）脂肪细胞特异性Nampt敲除（ANKO）小鼠具有多器官损伤，（骨骼肌、肝脏、WAT）胰岛素抵抗、低脂联素血症、适应性产热和全身能量代谢受损，以及对高热量和低热量挑战的燃料选择受损; 3）NAD+代谢与Caveolin-1（CAV 1）之间的新型分子联系，Caveolin-1是全身代谢灵活性的关键调节剂; 4）饮食限制和运动，众所周知的代谢灵活性增强剂，刺激WAT中NAMPT介导的NAD+生物合成;以及5）与我们的啮齿动物数据一致，肥胖症患者WAT NAMPT表达和NAD+浓度降低。基于这些发现，该更新申请将测试以下假设：NAMPT介导的NAD+生物合成调节WAT中的CAV 1和线粒体功能，WAT是代谢灵活性和葡萄糖代谢的关键效应子，WAT NAD+代谢缺陷是肥胖诱导的代谢不稳定性的新机制和治疗靶点。在目的1中，我们提出了两种新的小鼠模型，小鼠过表达NAMPT选择性内脏WAT（使用新的AAV系统）和他莫昔芬诱导ANKO（iANKO）小鼠，并评估代谢反应高脂肪饮食喂养和生活方式的改变（饮食限制，运动）。在目标2中，我们建议使用体外系统，并探讨四种机制（赖氨酸乙酰化的CAV 1，PPARG，sirtuins和氧化还原代谢），NAD+代谢与CAV 1和线粒体功能。最后，在目标3中，我们建议确定我们在小鼠模型（目标1）和细胞培养系统（目标2）中进行的研究的潜在临床相关性。具体而言，我们将评估两种潜在的“NAD+增强剂”，即生活方式改变（低热量饮食±监督运动训练）和烟酰胺单核苷酸（NMN）补充剂（250 mg/天，8周）对超重人群中WAT NAD+代谢、CAV 1和线粒体生物学的影响。从该提案中获得的预期结果将为脂肪组织NAD+生物学在调节代谢灵活性和葡萄糖代谢中的重要性提供新的见解。