Calorie restriction and aging

热量限制和衰老

• 批准号: 8552387
• 负责人: Rafael de Cabo
• 金额: $ 25.08万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8552387
• 关键词: Adherence; Affect; Age; Aging; Aging-Related Process; Animals; Antioxidants; Attenuated; Binding; Biochemical; Bioenergetics; Biogenesis; Caloric Restriction; Carbohydrates; Carcinogens; Cell Nucleus; Cell Proliferation; Cell Respiration; Cell membrane; Cells; Chemicals; Chronic Disease; Citric Acid Cycle; Cognition; Complex; Conflict (Psychology); Coupled; Curcumin; Cytoplasm; DNA Damage; Data; Development; Diet; Dietary Intervention; Disease; Drug Formulations; Drug Metabolic Detoxication; Electron Transport; Electrons; Energy Intake; Enzymes; Equilibrium; Evaluation; Exposure to; Faculty; Family; Fasting; Fatty Acids; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Glutathione S-Transferase; Goals; Growth; Health; Human; Hypothalamic structure; In Vitro; Incidence; Insulin; Insulin-Like Growth Factor I; Intervention; Invertebrates; Investigation; Investments; Laboratories; Laboratory Rat; Laboratory Study; Life; Liver; Longevity; Malignant Neoplasms; Malnutrition; Mammals; Measurable; Membrane Potentials; Mitochondria; Modeling; Molecular; Mus; NAD(P)H dehydrogenase (quinone) 1, human; NF-E2-related factor 2; NQO1 gene; Neurosecretory Systems; Nuclear; Oxidation-Reduction; Oxidative Stress; Oxygen Consumption; Pathway interactions; Performance; Peroxisome Proliferator-Activated Receptors; Phenotype; Physiological; Phytochemical; Play; Process; Production; Protons; Publishing; Quercetin; Reactive Oxygen Species; Regulation; Reporting; Repression; Research; Respiration; Response Elements; Resveratrol; Role; Scientist; Serum; Severities; Signal Pathway; Signal Transduction; Stress; Structure of nucleus infundibularis hypothalami; System; Tissues; Transplantation; Work; age effect; age related; anti aging; attenuation; biological adaptation to stress; carcinogenesis; cell growth; detection of nutrient; environmental agent; factor A; fatty acid metabolism; functional decline; growth hormone regulating factor; heme oxygenase-1; human Huntingtin protein; in vivo; insulin sensitivity; mimetics; mitochondrial dysfunction; mitochondrial genome; mutant; nuclear receptor coactivator 1; nuclear respiratory factor; nutrition; oxidation; oxidative damage; receptor; research and development; response; theories; transcription factor; tumor

The aims of this project are to assess the effects of aging and caloric restriction (CR) at a cellular and biochemical level of analysis, to identify physiological mechanisms associated with these effects, and to evaluate interventions/molecular pathways that might alter age-related declines in function. Laboratory studies consistently demonstrate extended lifespan in animals on calorie restriction (CR), where total caloric intake is reduced by 10-40% but adequate nutrition is otherwise maintained. CR has been further shown to delay the onset and severity of chronic diseases associated with aging such as cancer, and to extend the functional health span of important faculties like cognition. Less understood are the underlying mechanisms through which CR might act to induce such alterations. One theory postulates that CR's beneficial effects are intimately tied to the neuroendocrine response to low energy availability, of which the arcuate nucleus in the hypothalamus plays a pivotal role. CR induces measurable changes on circulating levels of several hormones and growth factors that regulate cell growth and proliferation. Serum obtained from CR animals alters growth, proliferation and stress responses of cells in culture. We have demonstrated that it is possible to investigate certain aspects of CR using this in vitro approach. This approach lends itself to a more rapid investigation of possible mechanisms and, perhaps more importantly to the research, development and rapid evaluation of interventions that would be able to induce or promote a phenotype similar to that seen with CR, essentially a CR mimetic. Below is the description of two of the most prominent lines of work in my laboratory associated with this project. Mitochondrial Biogenesis and Caloric Restriction. CR is hypothesized to decrease mitochondrial electron flow and proton leaks to attenuate damage due to reactive oxygen species (ROS). We have focused our research on a related, but different anti-aging mechanism of CR. Specifically, using both in vivo and in vitro analyses, we reported that CR reduces oxidative stress by stimulating the proliferation of mitochondria through a PGC1a signaling pathway. These mitochondria under CR conditions show less oxygen consumption, reduced membrane potential and generate less ROS than controls but remarkably are able to maintain their critical ATP production. Thus, CR can induce a PGC1a-dependent increase in mitochondria capable of efficient and balanced bioenergetics to reduce oxidative stress and attenuate age-dependent endogenous oxidative damage. In mammals, the regulation of mitochondrial biogenesis is complex, and it is not known whether the effects of CR on mitochondrial biogenesis are tissue-specific. Mitochondrial biogenesis is a highly regulated process that coordinates the activity of the approximately 1000 genes involved in mitochondrial function. This process requires coordination of the nuclear and mitochondrial genomes. Under CR, PGC-1α is expressed and activated, leading to an increase of mitochondrial mass. PGC-1α gene expression has been shown to be maintained with aging in CR models. In addition to PGC-1α there are other master regulators that are expressed under CR conditions like Peroxisome Proliferator Activated Receptor (PPAR) family and liver X receptor, which control fatty acid metabolism. PGC-1α seems to be a crucial factor in activation of cellular respiration. Its physiological importance has been demonstrated since repression of PGC-1α by a mutant form of the huntingtin protein leads to mitochondrial dysfunction whereas its over-expression rescues cells from the deleterious effect of huntingtin. PGC-1α specifically modulates the activity of several transcription factors and co-activators involved in mitochondrial respiration and biogenesis such as Nuclear Respiratory Factor 1 (NRF-1), NRF -2, PPARα, steroid receptor coactivator-1 and mitochondrial transcriptor factor A. NRF1 and NRF2 coordinate the expression of nuclear and mitochondrial genes that encode most of the subunits of mitochondrial complexes. Furthermore, PGC1-α activates the shift of substrate utilization from carbohydrates to fatty acids through co-regulation of PPARα. Although it has been reported that CR enhances mitochondrial performance, the mechanism remains controversial as reports conflict about the extent to which CR changes expression of genes involved in nutrient sensing, mitochondrial biogenesis, and other key mitochondrial enzymes involved in the Krebs cycle, β-oxidation, and electron transport chain activities in humans. Carcinogenesis and Caloric Restriction. Almost a century ago Moreschi and Rous published their separate observations on the impact of caloric restriction (CR) on transplanted and induced tumors. Years later, McCay and colleagues first observed lifespan extension in laboratory rats maintained on a CR diet. Since then, CR has been studied intensively with consistent results showing its beneficial effects on longevity, age-associated diseases, attenuation of functional declines, and carcinogenesis across a variety of species and diet formulations. However, the mechanism(s) underlying the effects of CR protection still remain unknown. Nevertheless, it is safe to say that the three most extensively studied hallmarks of CR are enhanced protection against induced and spontaneous carcinogenesis, reduced insulin/IGF-1 signaling, and increased median and maximum lifespan. Even if CR was shown to benefit human health, confer cancer protection, and increase longevity, it would be extremely difficult to achieve adherence to such a stringent diet that might require a reduction of 20-40% in caloric intake. To this end, considerable investment has been focused on dissecting the pathways that regulate CR benefits that could spur development of pharmacological agents potentially acting as CR mimetics. Several of the currently proposed CR mimetics are phytochemicals (resveratrol, quercetin, and curcumin) that act, at least in part, through the activation of the NF-E2-related factor 2 (Nrf2) pathway. Nrf2 is a transcription factor that binds to the antioxidant response element (ARE) of target genes as an adaptive response to oxidative stress and increases the transcription of a variety of anti-oxidative and carcinogen detoxification enzymes. Stress can result from a variety of causes including fasting, overfeeding, endogenous compounds, exposure to chemicals or environmental agents but generally leads to the production of ROS. As a result of ROS exposure, Nrf2, which is typically bound to Keap1 in the cytoplasm, where it undergoes proteolytic degradation and rapid turnover, is phosphorylated and translocates to the nucleus where it binds to ARE sequences to induce expression of multiple cytoprotective enzymes including NAD(P)H-quinone oxidoreductase 1 (NQO1), glutathione S-transferases (GSTs), and heme oxygenase-1. We have now shown that Nrf2 is responsible for the protection of CR against carcinogenesis. However, the lack of Nrf2 did not attenuate lifespan extension or alter the CR improvement on insulin sensitivity in the Nrf2 KO mice. Similar to our findings with induced carcinogenesis, Van Remmen et al. were the first to show that reduction of an antioxidant enzyme could markedly increase DNA damage and spontaneous cancer incidence without affecting survival and lifespan. However, this study is the first to demonstrate that distinct pathways exert beneficial effects of CR and suggests that many mechanisms are involved in its protection. Recent data from invertebrates suggested that Nrf2 or at least some of its downstream effectors could hold the key to caloric restriction and longevity

该项目的目的是在细胞和生化分析水平上评估衰老和热量限制（CR）的影响，确定与这些影响相关的生理机制，并评估可能改变与年龄相关的衰退的干预措施/分子途径在功能上。实验室研究一致证明，限制热量 (CR) 可以延长动物的寿命，即总热量摄入量减少 10-40%，但仍能保持充足的营养。 CR 已被进一步证明可以延缓癌症等与衰老相关的慢性疾病的发作和严重程度，并延长认知等重要功能的功能健康范围。 CR 可能诱发这种改变的潜在机制尚不清楚。一种理论认为，CR 的有益作用与神经内分泌对低能量可用性的反应密切相关，其中下丘脑的弓状核发挥着关键作用。 CR 会引起调节细胞生长和增殖的几种激素和生长因子的循环水平发生可测量的变化。从 CR 动物获得的血清会改变培养细胞的生长、增殖和应激反应。我们已经证明，使用这种体外方法研究 CR 的某些方面是可能的。这种方法有助于更快速地研究可能的机制，也许更重要的是，有助于研究、开发和快速评估能够诱导或促进与 CR 相似的表型（本质上是 CR 模拟物）的干预措施。以下是我的实验室与该项目相关的两个最重要的工作领域的描述。 线粒体生物发生和热量限制。 据推测，CR 可以减少线粒体电子流和质子泄漏，从而减轻活性氧 (ROS) 造成的损伤。我们的研究重点是 CR 的相关但不同的抗衰老机制。具体来说，通过体内和体外分析，我们发现 CR 通过 PGC1a 信号通路刺激线粒体增殖来减少氧化应激。 CR 条件下的这些线粒体比对照组显示出更少的耗氧量、降低的膜电位和产生更少的 ROS，但能够维持其关键的 ATP 产生。因此，CR 可以诱导 PGC1a 依赖性线粒体增加，从而有效且平衡地减少氧化应激并减弱年龄依赖性内源性氧化损伤。在哺乳动物中，线粒体生物发生的调节是复杂的，并且尚不清楚CR对线粒体生物发生的影响是否具有组织特异性。线粒体生物发生是一个高度调控的过程，协调参与线粒体功能的大约 1000 个基因的活性。这个过程需要核基因组和线粒体基因组的协调。 CR 下，PGC-1α 表达并激活，导致线粒体质量增加。在 CR 模型中，PGC-1α 基因表达已被证明随着衰老而得以维持。除了 PGC-1α 之外，还有其他在 CR 条件下表达的主调节因子，例如过氧化物酶体增殖物激活受体 (PPAR) 家族和肝脏 X 受体，它们控制脂肪酸代谢。 PGC-1α 似乎是细胞呼吸激活的关键因素。它的生理重要性已得到证明，因为亨廷顿蛋白的突变形式抑制 PGC-1α 会导致线粒体功能障碍，而其过度表达可以使细胞免受亨廷顿蛋白的有害影响。 PGC-1α 特异性调节参与线粒体呼吸和生物合成的多种转录因子和共激活因子的活性，例如核呼吸因子 1 (NRF-1)、NRF -2、PPARα、类固醇受体共激活因子-1 和线粒体转录因子 A。 NRF1 和 NRF2 协调编码线粒体复合物大部分亚基的核基因和线粒体基因的表达。此外，PGC1-α 通过 PPARα 的共同调节，激活底物利用从碳水化合物到脂肪酸的转变。尽管已有报道 CR 增强线粒体性能，但其机制仍存在争议，因为关于 CR 在多大程度上改变涉及营养感应、线粒体生物合成以及参与克雷布斯循环、β-氧化的其他关键线粒体酶的基因表达的程度，报告存在冲突。 ，以及人类的电子传递链活动。 致癌作用和热量限制。 大约一个世纪前，Moreschi 和 Rous 分别发表了关于热量限制 (CR) 对移植和诱导肿瘤影响的观察结果。几年后，麦凯和同事首次观察到维持 CR 饮食的实验室老鼠的寿命延长。从那时起，CR 得到了深入的研究，一致的结果表明它对各种物种和饮食配方的长寿、与年龄相关的疾病、减轻功能衰退和致癌作用具有有益作用。然而，CR 保护作用的潜在机制仍然未知。尽管如此，可以肯定地说，CR 的三个最广泛研究的标志是增强对诱发和自发癌变的保护、减少胰岛素/IGF-1 信号传导以及延长中位和最大寿命。 即使 CR 被证明有益于人类健康、提供癌症保护并延长寿命，但要坚持如此严格的饮食（可能需要减少 20-40% 的热量摄入）也是极其困难的。为此，大量投资集中在剖析调节 CR 益处的途径，这可能会刺激可能充当 CR 模拟物的药物制剂的开发。目前提出的几种 CR 模拟物是植物化学物质（白藜芦醇、槲皮素和姜黄素），它们至少部分通过激活 NF-E2 相关因子 2 (Nrf2) 途径发挥作用。 Nrf2是一种转录因子，与靶基因的抗氧化反应元件（ARE）结合，作为对氧化应激的适应性反应，并增加多种抗氧化和致癌物解毒酶的转录。压力可能由多种原因引起，包括禁食、过度喂养、内源性化合物、接触化学品或环境因素，但通常会导致活性氧的产生。由于 ROS 暴露，Nrf2（通常在细胞质中与 Keap1 结合，经历蛋白水解降解和快速周转）被磷酸化并易位到细胞核，在细胞核中与 ARE 序列结合，诱导包括 NAD 在内的多种细胞保护酶的表达(P)H-醌氧化还原酶 1 (NQO1)、谷胱甘肽 S-转移酶 (GST) 和血红素加氧酶-1。 我们现在已经证明 Nrf2 负责保护 CR 免受癌变。然而，缺乏 Nrf2 并不会减弱 Nrf2 KO 小鼠的寿命延长或改变胰岛素敏感性 CR 的改善。 Van Remmen 等人与我们在诱发致癌方面的发现类似。第一个证明减少抗氧化酶可以显着增加 DNA 损伤和自发性癌症发病率，而不影响生存和寿命。然而，这项研究首次证明不同的途径发挥 CR 的有益作用，并表明许多机制参与其保护。来自无脊椎动物的最新数据表明，Nrf2 或其至少一些下游效应器可能是热量限制和长寿的关键