Using massive-scale mRNA sequencing to unravel the mechanisms of ageing and its modulation by diet

阐明衰老的原因机制是我们这个时代最相关的科学问题之一。尤其是大脑老化是老年人的一个主要健康问题。它是认知能力下降的原因之一，也是阿尔茨海默氏症和帕金森氏症等神经退行性疾病的主要风险因素。研究人员研究衰老机制的一个主要工具是卡路里限制(CR)，它包括限制生物的正常食物摄入量。在包括哺乳动物在内的不同模式生物中，CR可显著延长寿命和保持健康。在啮齿类动物中，CR已被证明可以延缓大脑衰老。基因表达水平的变化与许多生物过程、细胞反应和疾病状态有关。虽然已经使用微阵列进行了几项关于衰老和CR的基因表达研究，但阐明衰老的转录特征仍然是一个关键的挑战。微阵列有重要的局限性，例如在对低丰度转录本的低敏感性方面。为了揭开衰老和调节衰老的饮食干预的转录网络，有必要获得老龄化和CR下基因表达变化的全球视角。该项目将利用下一代测序技术，以非凡的分辨率表征衰老基因表达的变化，并提供关于衰老及其饮食调节的新机制见解。在大鼠大脑中随年龄差异表达的基因以及在较长寿动物中随年龄差异表达减弱的基因将被识别出来。这将使大脑老化的分子生物标记物能够以出色的精度被确定。最近发现，α-硫辛酸(LA)对从CR转换为Ad lib的大鼠具有记忆效应：从CR转换为Ad lib的动物保持了CR的延长寿命特征，而从Ad lib转换为CR的动物则没有表现出延长的寿命。由于LA保留了转换为Ad lib的CR动物的长寿益处，因此将对在这些不同饮食条件下确定的转录本进行三角测量，以识别那些与CR的长寿效应和LA的记忆效应特别相关的转录本。这将对CR和LA的遗传和分子机制提供深入的认识。总而言之，通过使用不同寿命动物的样本，这些研究将提供关于衰老及其饮食调节的重要机制见解。

Elucidating the causal mechanisms of ageing is one of the most pertinent scientific questions of our time. Brain ageing in particular is a major health concern of ageing adults. It is a cause of cognitive decline and a major risk factor for neurodegenerative diseases like Alzheimer's and Parkinson's disease. A major tool available to researchers studying the mechanisms of ageing is caloric restriction (CR) which consists of restricting the normal (Ad lib) food intake of organisms. In different model organisms, including mammals, CR results in a robust extension of lifespan and preservation of health. In rodents, CR has been shown to delay brain ageing. Changes in gene expression levels are associated with many biological processes, cellular responses and disease states. Although several gene expression studies of ageing and CR have been conducted using microarrays, elucidating the transcriptional features of ageing remains a critical challenge. Microarrays have important limitations, for example in terms of low sensitivity to low abundance transcripts. In order to unravel transcriptional networks of ageing and of dietary interventions that modulate ageing, it is necessary to obtain a global view of gene expression changes under ageing and CR. This project will take advantage of next-generation sequencing technology to characterize the ageing gene expression changes with exceptional resolution and provide new mechanistic insights about ageing and its modulation by diet. Genes differentially expressed with age in the rat brain and those whose differential expression with age is attenuated in longer-lived animals will be identified. This will allow molecular biomarkers of brain ageing to be determined with outstanding precision. Alpha-lipoic acid (LA) was recently shown to induce a memory effect in rats switched from CR to Ad lib feeding: animals switching from CR to Ad lib feeding maintained the extended longevity characteristic of CR while conversely animals switching from Ad lib to CR did not exhibit extended longevity. Because LA preserves the longevity benefits of CR animals switched to Ad lib, transcripts identified in these different dietary conditions will be triangulated to identify those transcripts specifically associated with the longevity effects of CR with the memory effects of LA. This will provide insights into the genetic and molecular mechanisms of CR and LA. In conclusion, by employing samples from animals with varying longevity, these studies will provide important mechanistic insights about ageing and its modulation by diet.