Analysing the impact of extrachromosomal rDNA circles (ERCs) on the ageing yeast transcriptome [genome]

Here we analysed the widespread disruption of gene expression that accompanies yeast ageing, and surprisingly observed that this is completely independent of ERCs. Furthermore, we could not find subsets of genes that are differentially regulated in the presence of ERCs. High throughput imaging showed that the accumulation of Tom70-GFP which accompanies the onset of cell division defects at the Senescence Entry Point (SEP) also correlated poorly to ERC abundance, but allowed determination of a gene expression signature for the SEP. This signature included overexpression of mRNA from the chromosome XII region between the rDNA and the telomere (ChrXIIr), which has been previously noted to amplify during ageing.本研究分析了伴随酵母衰老发生的广泛基因表达失调现象，意外发现该失调完全独立于染色体外rDNA环（extrachromosomal rDNA circles, ERCs）。此外，本研究未发现存在ERCs时存在差异调控的基因子集。高通量成像结果显示，伴随衰老起始点（Senescence Entry Point, SEP）处细胞分裂缺陷出现的Tom70-GFP蛋白积累，与ERCs丰度的相关性极弱，但该蛋白积累可用于确定衰老起始点的基因表达特征。该特征包含12号染色体上核糖体DNA（rDNA）与端粒之间区域（ChrXIIr）的mRNA过表达，这一现象此前已被报道会在衰老过程中发生扩增。