Genome stability established through epigenome plasticity during ageing and rejuvenation

表观遗传改变和基因组不稳定是衰老的标志。然而，部分由于缺乏可靠的模型和技术，这些年龄相关的遗传和表观遗传改变的确切性质及其在表型可塑性中的功能相关性尚不清楚。我们开发了一种新的小鼠模型，在这种模型中，我们能够在成年期开启/关闭基础自噬，并发现减少的自噬会加速衰老，并且这种过早衰老的表型可以通过随后的自噬恢复来“分段”拯救。引人注目的是，这种“返老还童”伴随着肿瘤发生的增加。我们推断，年龄相关的代谢应激（减少的基础自噬）诱导基因组和表观基因组改变，后者可能是可逆的或不可逆的，并且这些改变共同提供了最佳条件下的选择压力（即，在年龄逆转时）。利用我们新的无免疫沉淀表观基因组分析方法，该方法能够分析低输入组织的表观基因组谱，我们将确定小鼠衰老和年龄逆转过程中年龄相关表观遗传变化和遗传突变的动态性质。这项技术也将被应用于检测与特定表观遗传标记相邻的年龄相关的遗传变化：我们设想，在年龄逆转后，功能相关的突变可能会增加或减少。这些方法将通过这些表观基因组状态提供对基因组不稳定性建立背后的机制的洞察。与此同时，我们还将开发一个高通量单细胞表观基因组测序平台，以改善细胞类型特异性，与我们的复兴模型一起，将有可能在单细胞水平上识别衰老中的功能组分以及“乘客”（epi-）遗传事件。

Epigenetic alterations and genome instability are hallmark of ageing. However, partially due to a lack of robust models and technologies, the precise nature of these age-associated genetic and epigenetic alterations and their functional relevance in the plasticity of the phenotype are unclear. We have developed a new mouse model, in which we are able to switch on/off basal autophagy in adulthood and have found that reduced autophagy accelerates ageing and that this premature ageing phenotype can be 'segmentally' rescued by subsequent autophagy restoration. Strikingly, this 'rejuvenation' is accompanied by increased tumorigenesis. We reason that age-associated metabolic stress (reduced basal autophagy) induces genomic and epigenomic alterations, the latter of which could be either reversible or irreversible, and that those alterations collectively provide a selective pressure under optimal conditions (i.e., upon age-reversal). Taking advantage of our new immunoprecipitation-free epigenome profiling method, which is capable of assaying the epigenomic profiles from low-input tissues, we will determine the dynamic nature of the age-associated epigenetic changes and genetic mutations during ageing and age-reversal in mice. This technology will also be applied to detect the age-associated genetic changes that occur adjacent to specific epigenetic marks: we envisage that functionally relevant mutations may be enriched or diminished after the age-reversal. These approaches will provide an insight into the mechanism behind the establishment of genomic instability through these epigenomic states. In parallel, we will also develop a high-throughput single-cell epigenome sequencing platform to refine cell type specificity, which, together with our rejuvenation model, will potentially identify functional components as well as 'passenger' (epi-)genetic events in ageing at a single-cell level.