Functional Genomic Study of Aging and Aging Intervention

衰老的功能基因组研究和衰老干预

• 批准号: 7327063
• 负责人: Sige Zou
• 金额: --
• 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/7327063
• 关键词: Functional; Genomic; Study; Aging; Intervention

The aim of this project is to identify aging-regulated genes at the molecular and tissue levels, to investigate molecular mechanisms of lifespan extension by longevity genes, and to identify efficient prolongevity interventions. To achieve our goals, we are utilizing three invertebrate systems, the Mexican fruit fly (mexfly), A. ludens, and the fly, D. melanogaster, and the nematode, C. elegans. Lifespan is influenced by a number of genetic and environmental factors. One of the most robust environmental manipulations of lifespan is dietary restriction (DR). DR has been shown to extend lifespan in many species, ranging from invertebrates to mammals, indicating that DR might retard aging if applied in humans. However, it would be challenging to impose long-term DR in humans. An alternative strategy would be to apply pharmaceutical or nutraceutical compounds to induce responses that would mimic DR. A few compounds have been shown to have this effect in model organisms. However, the number is still small and little is known about mechanisms by which these compounds extend lifespan. Genetic analyses of model organisms have uncovered mutations in a number of genes that can affect lifespan. Changes in gene expression in aging have been observed in a number of organisms, including worms, flies, rodents, primates and human beings. However, little is known about how different tissues age, and how longevity genes and prolongevity interventions influence aging. To address tissue-specific aging, we have systematically investigated tissue-specific factors that affect lifespan and aging processes. We have measured the expression profile of aging for seven tissues from fly, including brain, muscle and tissues in the digestive and reproductive systems, which represent different physiological functions. Hundreds of genes have been identified to show significant changes at the transcript level in aging in each tissue. Very few of these tissue-specific changes were shared among all the tissues, suggesting that different tissues age in unique ways. However, some of the aging-related changes are shared among two or more tissues, suggesting that common molecular features do exist among different tissues in aging. As an example, we have found genes involved a major metabolic pathway, TCA cycle, are down-regulated in brain, gut, muscle and testis but not fat tissue, accessory gland and malpighian tubule in aging. To study the mechanisms of lifespan extension by the longevity genes at the tissue and molecular levels, we have chosen to study the methuselah mutant fly, which has an extended lifespan. We have measured molecular changes of this mutant across age for the seven tissues described above. We have compared these changes to those in the wild type fly strain at the molecular and tissue levels. Several hundreds of genes have been identified to have tissue-specific changes between wild type and methuselah flies. This assessment will elucidate molecular and cellular mechanisms on how the methuselah gene regulates lifespan at the tissue level. Similar approaches will be applied to study mechanisms by which prolongevity interventions extend lifespan at the tissue levels in the future. Dietary supplements are widely used with the belief that they can forestall disease and increase longevity. Few systematic attempts have been made to confirm prolongevity claims made or to investigate potentially effective interventions. We are currently developing a high-throughput system by using mexfly. The main reason to use mexflies is that we have easy access to millions of mexflies available daily in the Moscafrut mass-rearing facility at Tapachula, Chiapas, Mexico. This minimizes our efforts to obtain a large number of animals for mortality analysis required for the high-throughput lifespan screen. There are several other advantages as well. The size of mexflies is relatively large relative to D. melanogaster so that it is easy to sort out by sex and to measure food intake, the latter of which is critical for assessing dosage effects of compounds. Moreover, unlike D. melanogaster, mexflies and medflies can feed on a dry food source but lay their eggs on a different medium such as organdy mesh, which facilitates investigation of effects of compounds on reproduction independent of diet. Finally, the expected lifespan of mexflies on a regular diet is approximately 2 months, which is short enough for conducting a lifespan screen and but long enough for demographic studies of aging. As an example, we have assessed the effects of supplementation of two related antioxidants, alpha-tocopherol and gamma-tocopherol, on lifespan of mexflies. We have found that these two antioxidants have marginal effects on lifespan extension, which is consistent with what we have observed in D. melanogaster. Utilization of the high-throughput system will provide reliable and statistically convincing results on the effects of aging interventions. Systematic evaluation of prolongevity interventions will not only allow identification of effective anti-aging compounds but also uncover mechanisms of lifespan extension by dietary supplementation. This approach should prove valuable to advance the objective of experimental gerontology to investigate and develop aging interventions in mammals. Our understanding of molecular mechanisms of DR comes primarily from studies of genetically amenable systems including yeast, worms, and flies, where DR has been imposed by either diluting the food source or by using genetic mutations that reduce feeding efficiency. However, a major drawback of these approaches is that there remains substantial uncertainty in determining the exact caloric intake of individuals under these DR paradigms, unlike this ability in studies of higher organisms. This led us to discover and develop an alternative dietary paradigm that can extend lifespan in C. elegans. We have found that a dietary deprivation (DD) regimen, in which the food source is completely removed from adults, can prolong adult lifespan by 45%. Since this regimen involves complete removal of the food source, the problem of controlling food intake, which has hampered interpretation of past studies, is alleviated. Using this unambiguous method, we have started investigating the genetic pathways necessary for lifespan extension by diet. Genome-wide transcript profiles of DD response are measured and compared to that of DR to reveal similarities between DD and DR paradigm. To identify which genetic pathways are required for the DD response, a genetic screen is being conducted for DD-associated genes identified from genomic studies as well as for genes known to extend lifespan. This analysis should reveal mechanisms governing longevity under different environmental especially dietary conditions. Considering the similarities between DD and DR, some of the DD mechanisms should be evolutionarily conserved, which will advance knowledge about effects of diet on aging and longevity in mammals. In summary, we have applied three different invertebrate species to address issues related to dietary regulation of lifespan by taking advantage of unique features of each system. With D. melanogaster, we are studying mechanisms by which prolongevity interventions and longevity genes extend lifespan at molecular and tissue levels. We are using mexflies to identify effective prolongevity interventions, which should provide guidance for further investigation of aging interventions in mammals. By utilizing a unique and robust dietary regimen in C. elegans, we are dissecting molecular mechanisms of dietary regulation of lifespan. Identification of the conserved features in aging and efficient prolongevity interventions are clearly critical for us

该项目的目的是在分子和组织水平上识别衰老调节基因，研究长寿基因延长寿命的分子机制，并确定有效的长寿干预措施。为了实现我们的目标，我们正在利用三种无脊椎动物系统：墨西哥果蝇 (mexfly)、A. ludens、果蝇、D. melanogaster 和线虫、C. elegans。寿命受到许多遗传和环境因素的影响。对寿命最有效的环境控制之一是饮食限制（DR）。 DR 已被证明可以延长从无脊椎动物到哺乳动物等许多物种的寿命，这表明如果应用于人类，DR 可能会延缓衰老。然而，在人类身上实施长期的 DR 将具有挑战性。另一种策略是应用药物或营养化合物来诱导模仿 DR 的反应。一些化合物已被证明在模型生物体中具有这种作用。然而，数量仍然很少，而且人们对这些化合物延长寿命的机制知之甚少。对模型生物体的遗传分析发现了许多可能影响寿命的基因突变。在许多生物体中都观察到了衰老过程中基因表达的变化，包括蠕虫、苍蝇、啮齿动物、灵长类动物和人类。然而，人们对不同组织如何衰老，以及长寿基因和长寿干预措施如何影响衰老知之甚少。为了解决组织特异性衰老问题，我们系统地研究了影响寿命和衰老过程的组织特异性因素。我们测量了果蝇七种组织的衰老表达谱，包括大脑、肌肉以及消化系统和生殖系统的组织，它们代表了不同的生理功能。数百个基因已被发现在每个组织的衰老过程中在转录水平上显示出显着的变化。这些组织特异性变化很少在所有组织之间共享，这表明不同的组织以独特的方式老化。然而，一些与衰老相关的变化是两个或多个组织共有的，这表明衰老过程中不同组织之间确实存在共同的分子特征。例如，我们发现涉及主要代谢途径（TCA 循环）的基因在衰老过程中在大脑、肠道、肌肉和睾丸中下调，但在脂肪组织、副腺和马氏小管中却没有下调。为了从组织和分子水平上研究长寿基因延长寿命的机制，我们选择了研究具有延长寿命的methuselah突变果蝇。我们测量了上述七种组织中这种突变体随年龄变化的分子变化。我们在分子和组织水平上将这些变化与野生型果蝇品系的变化进行了比较。已鉴定出数百个基因在野生型果蝇和玛苏塞拉果蝇之间具有组织特异性变化。该评估将阐明 methuselah 基因如何在组织水平上调节寿命的分子和细胞机制。未来，类似的方法将应用于研究延长组织水平寿命的干预机制。膳食补充剂被广泛使用，人们相信它们可以预防疾病并延长寿命。很少有系统性的尝试来证实所提出的长寿主张或调查潜在有效的干预措施。我们目前正在使用 mexfly 开发高通量系统。使用 mexflies 的主要原因是，我们每天可以在墨西哥恰帕斯州塔帕丘拉的 Moscafrut 大规模饲养设施中轻松获得数百万只 mexflies。这最大限度地减少了我们获取大量动物进行高通量寿命筛选所需的死亡率分析的努力。还有其他一些优点。墨西哥果蝇的体型相对黑腹果蝇较大，因此很容易按性别分类并测量食物摄入量，后者对于评估化合物的剂量效应至关重要。此外，与黑腹果蝇不同，墨西哥果蝇和地中海果蝇可以以干燥食物为食，但将卵产在不同的介质上，例如透明纱网，这有助于研究化合物对独立于饮食的繁殖的影响。最后，正常饮食的墨西哥果蝇的预期寿命约为 2 个月，这对于进行寿命筛查来说足够短，但对于衰老的人口统计研究来说却足够长。例如，我们评估了补充两种相关抗氧化剂（α-生育酚和γ-生育酚）对墨西哥果蝇寿命的影响。我们发现这两种抗氧化剂对延长寿命具有边际效应，这与我们在黑腹果蝇中观察到的结果一致。高通量系统的利用将为衰老干预措施的影响提供可靠且统计上令人信服的结果。对长寿干预措施的系统评估不仅可以识别有效的抗衰老化合物，还可以揭示通过膳食补充剂延长寿命的机制。这种方法对于推进实验老年学研究和开发哺乳动物衰老干预措施的目标具有重要价值。我们对 DR 分子机制的理解主要来自对包括酵母、蠕虫和苍蝇在内的遗传适应性系统的研究，其中 DR 是通过稀释食物来源或使用降低喂养效率的基因突变来实施的。然而，这些方法的一个主要缺点是，在这些 DR 范式下确定个体的确切热量摄入仍然存在很大的不确定性，这与高等生物研究中的这种能力不同。这促使我们发现并开发了一种可以延长线虫寿命的替代饮食模式。我们发现，饮食剥夺 (DD) 疗法（即完全去除成年人的食物来源）可以将成年人的寿命延长 45%。由于该方案涉及完全去除食物来源，因此阻碍了对过去研究的解释的控制食物摄入的问题得到了缓解。利用这种明确的方法，我们开始研究通过饮食延长寿命所需的遗传途径。测量 DD 反应的全基因组转录谱，并将其与 DR 的转录谱进行比较，以揭示 DD 和 DR 范式之间的相似性。为了确定 DD 反应所需的遗传途径，正在对从基因组研究中鉴定出的 DD 相关基因以及已知可延长寿命的基因进行遗传筛选。该分析应该揭示不同环境尤其是饮食条件下控制长寿的机制。考虑到 DD 和 DR 之间的相似性，一些 DD 机制在进化上应该是保守的，这将增进人们对饮食对哺乳动物衰老和长寿影响的认识。总之，我们利用三种不同的无脊椎动物物种的独特特征来解决与寿命饮食调节相关的问题。我们正在利用黑腹果蝇研究长寿干预措施和长寿基因在分子和组织水平上延长寿命的机制。我们正在利用墨西哥果蝇来确定有效的长寿干预措施，这将为进一步研究哺乳动物的衰老干预措施提供指导。通过利用线虫独特而强大的饮食方案，我们正在剖析饮食调节寿命的分子机制。识别衰老过程中的保守特征和有效的长寿干预措施对我们来说显然至关重要