Analyzing the impact of extrachromosomal rDNA circles (ERCs) on the ageing yeast transcriptome

Here we analyzed 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出现的广泛基因表达紊乱现象，意外发现该现象完全不依赖于染色体外核糖体DNA环（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，伴随衰老进入点（SEP）处细胞分裂缺陷发生而积累的Tom70绿色荧光蛋白（Tom70-GFP），其积累量与ERCs丰度的相关性极弱，但该积累现象可用于确定SEP的基因表达特征谱。该特征谱包含位于核糖体DNA（rDNA）与端粒之间的XII号染色体区域（ChrXIIr）的mRNA过表达现象，该区域此前已有研究报道其会在衰老过程中发生扩增。