Elucidating the Role of Endothelial NAD Metabolism in Atherosclerosis

阐明内皮 NAD 代谢在动脉粥样硬化中的作用

基本信息

批准号：
10655649
负责人：
Ioana Soaita
金额：
$ 1.3万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-07-01 至 2023-11-03
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10655649
关键词：
Acceleration Adenine Nucleotides Adhesions Age Aging Aorta Area Arterial Fatty Streak Atherosclerosis Blood Vessels Bypass Carbon Isotopes Cardiovascular system Cause of Death Cells Clinical Consumption Coupled Deacetylase Deacetylation Development Endothelial Cells Endothelium Enzymes Equilibrium Event Family Functional disorder Histology Homeostasis Human Hyperlipidemia Impairment Inflammation Intervention Label Lead Lipids Liver Mediating Metabolic Metabolism Methods Modeling Mus NOS3 gene Niacinamide Nicotinamide adenine dinucleotide Nitric Oxide Oils Oral Oral Administration Oxidative Stress Pathogenesis Pathologic Pathology Pathway interactions Phenotype Prevalence Process Production Public Health Reaction Reporting Risk Factors Role SIRT1 gene Sirtuins Stains Supplementation Testing Text Therapeutic Tissues United States Vasodilation Work aged atherogenesis atherosclerosis risk career experimental study gain of function human disease improved in vitro activity loss of function metabolic abnormality assessment modifiable risk mouse model nicotinamide phosphoribosyltransferase nicotinamide-beta-riboside novel therapeutic intervention nucleotide metabolism overexpression prevent stable isotope stress reduction

项目摘要

Project Summary Atherosclerosis remains a leading cause of death in the United States, even in the context of aggressive clinical and public health efforts to lower risk factors such as hyperlipidemia. Thus, there is a significant need for better mechanistic understanding of atherosclerosis pathogenesis in order to develop novel therapeutic strategies downstream of circulating risk factors. Atherosclerosis pathogenesis begins in the endothelial layer of the arterial wall: endothelial cell dysfunction (ECD) and EC inflammation precede atherosclerotic plaque formation and are associated with adverse cardiovascular events. Both ECD and EC inflammation increase with age, and age is a major non-modifiable risk factor for atherosclerosis. Importantly, activation of sirtuin (SIRT) family of nicotinamide adenine dinucleotide (NAD+) - dependent deacetylases, particularly SIRT1, has been reported to slow a variety of age-associated phenotypes. In particular, our lab and others have shown that levels of endothelial NAD+ decrease with age, and that endothelial-specific overexpression of SIRT1 is sufficient to slow ECD and progression of atherosclerosis. Furthermore, oral administration of NAD+ precursors in aged mice increases aortic SIRT1 expression and activity, and reduces ECD, suggesting that increasing NAD+ availability can promote SIRT1 activity in aged ECs. Loss of NAD+ balance thus appears to be central to atherogenesis, but little is known about how ECs maintain NAD homeostasis. Quantitative flux analysis of NAD+ precursors in live mice has recently uncovered that liver-derived nicotinamide (NAM) is the main circulating NAD+ precursor that reaches tissues. This suggests that the enzyme NAM phosphoribosyltransferase (NAMPT), which catalyzes the first and rate-limiting step in NAD+ synthesis from NAM, is critical for producing endothelial NAD+ and maintaining the activity of NAD+ - dependent enzymes. Thus, I hypothesize that endothelial NAMPT is cell-autonomously required to produce NAD+ and maintain endothelial SIRT1 activity, and that endothelial NAMPT overexpression will protect against progression of atherosclerosis. To test this hypothesis, we have generated endothelial-specific gain-of-function (GOF) and loss-of-function (LOF) NAMPT mouse models. In Aim 1, I will use cultured primary arterial ECs and stable isotope carbon tracing coupled with quantitative flux analysis to calculate rates of NAMPT NAD+ production and SIRT1 NAD+ consumption. I will also determine if NAMPT activity is required for SIRT1 deacetylation activity, and if NAMPT activation is sufficient to maintain SIRT1 activity upon oxidative stress. In Aim 2, I will test if NAMPT GOF or oral NAD+ supplementation is sufficient to slow progression of atherosclerosis, and if NAMPT LOF accelerates atherosclerosis. Ultimately, this work will improve understanding of EC NAD+ metabolism and its role in maintaining SIRT1 activity, and inform if NAMPT activation and/or NAD+ replenishment could be a therapeutic avenue for reducing the burden of atherosclerosis independently of circulating risk factors such as hyperlipidemia.

项目概要即使在积极的临床治疗背景下，动脉粥样硬化仍然是美国死亡的主要原因以及降低高脂血症等危险因素的公共卫生努力。因此，迫切需要更好的对动脉粥样硬化发病机制的机制理解，以开发新的治疗策略循环危险因素的下游。动脉粥样硬化的发病机制始于动脉内皮层壁：内皮细胞功能障碍 (ECD) 和 EC 炎症先于动脉粥样硬化斑块形成，并且是与不良心血管事件有关。 ECD 和 EC 炎症均随着年龄的增长而增加，而年龄是动脉粥样硬化的主要不可改变的危险因素。重要的是，激活烟酰胺去乙酰化酶 (SIRT) 家族据报道，腺嘌呤二核苷酸 (NAD+) 依赖性脱乙酰酶，特别是 SIRT1，可以减缓多种与年龄相关的表型。特别是，我们的实验室和其他实验室已经表明，内皮 NAD+ 水平随着年龄的增长而减少，SIRT1 的内皮特异性过度表达足以减缓 ECD 和动脉粥样硬化的进展。此外，老年小鼠口服 NAD+ 前体会增加主动脉 SIRT1 表达和活性，并降低 ECD，表明增加 NAD+ 可用性可以促进老化 EC 中的 SIRT1 活性。因此，NAD+ 平衡的丧失似乎是动脉粥样硬化形成的核心，但人们知之甚少关于 EC 如何维持 NAD 稳态。活体小鼠 NAD+ 前体的定量通量分析最近发现，肝源性烟酰胺 (NAM) 是主要的循环 NAD+ 前体，可达到组织。这表明 NAM 磷酸核糖基转移酶 (NAMPT) 催化第一个和 NAM 合成 NAD+ 的限速步骤，对于产生内皮 NAD+ 和维持 NAD+ 依赖性酶的活性。因此，我假设内皮 NAMPT 是细胞自主的产生 NAD+ 和维持内皮 SIRT1 活性所需，并且内皮 NAMPT 过度表达将防止动脉粥样硬化的进展。为了检验这个假设，我们有生成内皮特异性功能获得（GOF）和功能丧失（LOF）NAMPT 小鼠模型。瞄准 1，我将使用培养的原代动脉EC和稳定同位素碳示踪以及定量通量分析计算 NAMPT NAD+ 产生率和 SIRT1 NAD+ 消耗率。我还将确定 NAMPT 是否 SIRT1 脱乙酰化活性需要活性，并且 NAMPT 激活是否足以维持 SIRT1 活性在氧化应激下。在目标 2 中，我将测试 NAMPT GOF 或口服 NAD+ 补充剂是否足以减缓动脉粥样硬化的进展，以及 NAMPT LOF 是否会加速动脉粥样硬化。最终，这项工作将得到改善了解 EC NAD+ 代谢及其在维持 SIRT1 活性中的作用，并告知 NAMPT 是否激活和/或补充 NAD+ 可能是减轻动脉粥样硬化负担的治疗途径与高脂血症等循环危险因素无关。