eNAMPT-mediated adipo-hypothalamic communication for NAD+ production and aging

项目名称 ENAMPT介导的脂肪-下丘脑通讯与NAD+的产生和衰老 摘要 近年来，烟酰胺腺嘌呤二核苷酸(NAD+)代谢已成为研究的中心课题。 衰老和长寿研究领域。已经确定，NAD+的可用性会随着年龄的增长而下降 在系统水平上，在不同的模式生物中触发各种与年龄相关的病理生理变化。 在哺乳动物NAD+生物合成中，烟酰胺磷酸核糖基转移酶(NAMPT)是 将烟酰胺和5‘-磷酸核糖焦磷酸转化为烟酰胺单核苷酸(NMN)，以及 重要的NAD+中间体。有趣的是，哺乳动物中有两种不同形式的NAMPT：Intra-NAMPT和Intra-NAMPT 胞外NAMPT(分别为iNAMPT和eNAMPT)。我们之前已经演示过eNAMPT 在脂肪组织和下丘脑之间介导一种新的组织间通讯系统，调节 下丘脑NAD+水平和功能。我们现在已经发现eNAMPT是通过外切体携带的 老鼠和人类体内的循环。外体eNAMPT内化到初级下丘脑神经元和 促进细胞内NAD+的生物合成。能够维持较高水平的基因工程小鼠 老年人外体eNAMPT表现出多种抗衰老表型，并显著延长了 健康跨度。这些新的发现证明了一种新的调节衰老过程的系统机制 并由外显子介导的eNAMPT递送驱动，确定健康寿命/寿命。因此，我们 假设外体eNAMPT通过与特定组织的相互作用被传递到特定组织 受体样蛋白，调节各种组织功能，包括海马体依赖的认知功能 功能。NAMPT的K53R突变体，其分泌增强，可用于遗传 减轻小鼠年龄相关功能衰退的工程化生物。我们将解决这一假设 通过以下具体目的：1)为了阐明外体eNAMPT的靶向机制，我们将研究 对NAMPT蛋白结构的要求以及对一个潜在的外体受体候选的测试 ENAMPT需要内化，2)进一步分析补充含有eNAMPT的外切体的效果 老年小鼠，我们将分析它们对海马体介导的认知功能的影响，以及3)测试 ENAMPT作为一种抗衰老生物，我们将考察eNAMPT突变体封装成 Exosome对老龄小鼠认知、行为和其他组织功能的影响。因此，预期的结果是 这项拟议的研究将为了解全身NAD+动态平衡如何调节衰老开辟一条新途径 和长寿，并开发一种新的抗衰老干预措施，利用外体eNAMPT作为生物制剂。

TITLE OF PROJECT eNAMPT-mediated adipo-hypothalamic communication for NAD+ production and aging ABSTRACT In recent years, nicotinamide adenine dinucleotide (NAD+) metabolism has emerged as a central topic in the field of aging and longevity research. It has been established that NAD+ availability declines over age at a systemic level, triggering a variety of age-associated pathophysiological changes in diverse model organisms. In mammalian NAD+ biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme that converts nicotinamide and 5’-phosphoribosyl-pyrophosphate to nicotinamide mononucleotide (NMN), an important NAD+ intermediate. Interestingly, there are two distinct forms of NAMPT in mammals: intra- and extracellular NAMPT (iNAMPT and eNAMPT, respectively). We have previously demonstrated that eNAMPT mediates a novel intertissue communication system between adipose tissue and the hypothalamus, regulating hypothalamic NAD+ levels and functions. We have now found that eNAMPT is carried in exosomes through the circulation in mice and humans. Exosomal eNAMPT is internalized into primary hypothalamic neurons and enhances NAD+ biosynthesis intracellularly. The genetically engineered mice that can maintain higher levels of exosomal eNAMPT at old ages exhibit a variety of anti-aging phenotypes and a significant extension of healthspan. These new findings demonstrate a novel systemic mechanism that regulates the process of aging and determines healthspan/lifespan, driven by an exosome-mediated delivery of eNAMPT. Thus, we hypothesize that exosomal eNAMPT is delivered to specific tissues through the interaction with a specific receptor-like protein and regulates various tissue functions, including the hippocampus-dependent cognitive functions. The K53R mutant of NAMPT, whose secretion is enhanced, could be used as a genetically engineered biologic that mitigates age-associated functional decline in mice. We will address this hypothesis by the following specific aims: 1) To elucidate the mechanism of exosomal eNAMPT targeting, we will examine the requirement of the NAMPT protein structure and also test a potential receptor candidate for exosomal eNAMPT to be internalized, 2) to further analyze the effects of supplementing eNAMPT-containing exosomes in aged mice, we will analyze their effect on the hippocampus-mediated cognitive functions, and 3) to test eNAMPT as an anti-aging biologic, we will examine the effects of eNAMPT mutants encapsulated into exosomes on cognitive, behavioral, and other tissue functions in aged mice. Thus, the anticipated outcome of the proposed research will open a new avenue to understand how systemic NAD+ homeostasis regulates aging and longevity and develop a novel anti-aging intervention by using exosomal eNAMPT as a biologic.