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，以识别与这些作用相关的生理机制，并评估可能会改变年龄相关的功能下降的干预措施/分子途径。实验室研究始终表明，在卡路里限制（CR）中，动物的寿命延长，其中总热量摄入量减少了10-40％，但否则可以维持足够的营养。 CR进一步证明，可以延迟与癌症等衰老相关的慢性疾病的发作和严重程度，并扩大重要能力等重要能力的功能健康跨度。 CR可能会引起此类改变的基本机制较少了解。一种理论假设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，下丘脑中的弓形核起着关键作用。 CR诱导几种激素的循环水平和调节细胞生长和增殖的生长因子的可测量变化。从CR动物获得的血清会改变培养物中细胞的生长，增殖和应激反应。我们已经证明，可以使用这种体外方法研究CR的某些方面。这种方法使自己对可能的机制进行了更快速的研究，也许更重要的是，对干预措施的研究，开发和快速评估，这些干预措施能够诱导或促进与CR相似的表型，本质上是CR模拟的。以下是我实验室中与该项目相关的两个最突出的工作的描述。 线粒体生物发生和热量限制。 假设CR可减少线粒体电子流量和质子泄漏，以减轻因活性氧（ROS）而导致的损害。我们将研究重点放在CR的相关但不同的抗衰老机制上。具体而言，使用体内和体外分析，我们报告了CR通过通过PGC1A信号通路刺激线粒体的增殖来降低氧化应激。在CR条件下，这些线粒体的消耗量较小，膜电位降低，而产生的ROS比对照组少，但显着能够维持其关键的ATP产生。因此，CR可以诱导能够有效且平衡的生物能量的线粒体中PGC1A依赖性增加，以减少氧化应激并减轻依赖年龄的内源性氧化损害。在哺乳动物中，线粒体生物发生的调节很复杂，尚不清楚Cr对线粒体生物发生的影响是否是组织特异性的。线粒体生物发生是一个高度调控的过程，可协调大约1000个参与线粒体功能的活性。这个过程需要协调核和线粒体基因组。在CR下，PGC-1α被表达并激活，导致线粒体质量增加。 PGC-1α基因表达已显示在CR模型中与衰老保持维持。除PGC-1α外，还有其他主要调节剂在CR条件下表达，例如过氧化物酶体增殖物激活受体（PPAR）家族和肝脏X受体，这些受体控制脂肪酸代谢。 PGC-1α似乎是细胞呼吸激活的关键因素。自从亨廷顿蛋白的突变形式抑制PGC-1α以来，它的生理重要性已得到证明，导致线粒体功能障碍，而其过表达使细胞免于亨廷汀的有害作用。 PGC-1α特别调节了与线粒体呼吸和生物发生有关的几个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），NRF -2，PPARα，类固醇受体共振剂1和线粒体转录因子A. NRF1和NRF2的核定核的表达和MIT核的表达量很高，并构成了核的表达。线粒体复合物。此外，PGC1-α通过PPARα的共调节激活了底物利用率从碳水化合物到脂肪酸的转移。尽管据报道CR可以增强线粒体性能，但该机制仍然有争议，因为报道发生了报道，报道说CR会改变与营养感应，线粒体生物发生，线粒体生物发生以及其他关键的线粒体酶有关的程度，涉及KREBS循环，β-氧化和电子传输链的癌症。 致癌和热量限制。 大约一个世纪前，莫雷斯基（Moreschi）和鲁斯（Rous）发表了关于热量限制（CR）对移植和诱导肿瘤的影响的单独观察。多年后，麦凯及其同事首先观察到在CR饮食中维持实验室大鼠的寿命延长。从那时起，对CR进行了深入的研究，结果表明其对寿命，与年龄相关的疾病，功能下降的衰减衰减以及各种物种和饮食配方中的致癌作用。但是，CR保护作用的基础机制仍然未知。但是，可以肯定地说，最广泛研究的CR的三个标志是对诱导和自发的癌变的保护，胰岛素/IGF-1信号的减少，中位和最大寿命增加。 即使证明CR有益于人类健康，赋予癌症保护并增加寿命，也很难遵守这种严格的饮食，这可能需要减少20-40％的热量摄入量。为此，大量的投资集中在剖析规范CR益处的途径上，这些途径可能刺激了可能充当CR Mimetics的药理学剂的发展。当前提出的几种CR Mimetics是植物化学物质（白藜芦醇，槲皮素和姜黄素），它们至少通过激活NF-E2相关因子2（NRF2）途径而起作用。 NRF2是与靶基因的抗氧化反应元件（IS）结合的转录因子，作为对氧化应激的适应性反应，并增加了多种抗氧化和致癌酶的转录。压力可能是由于禁食，过度喂养，内源性化合物，暴露于化学物质或环境剂的各种原因而造成的，但通常会导致ROS的产生。 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-转移酶（GSTS）和血红素氧酶-1。 我们现在已经表明，NRF2负责保护CR免受致癌作用。但是，缺乏NRF2并未减弱寿命延伸或改变NRF2 KO小鼠胰岛素敏感性的CR改善。与我们诱导的致癌物的发现相似，Van Remmen等人。是第一个证明抗氧化剂酶的减少可以显着增加DNA损伤和自发性癌症发病率而不会影响生存和寿命。但是，这项研究是第一个证明不同途径具有CR的有益作用的研究，并表明其保护涉及许多机制。无脊椎动物的最新数据表明，NRF2或至少某些下游效应器可以持有热量限制和寿命的关键