Ageing affects DNA methylation and transcriptional cell-to-cell variability in muscle stem cells [scBS-seq]

Age-related tissue alterations have been associated with a decline in stem cell number and function. Increased cell-to-cell variability in transcription or epigenetic marks has been proposed to be a major hallmark of ageing. Here, using parallel single-cell transcriptome and DNA methylome profiling, we find a global increase of uncoordinated transcriptional heterogeneity and context-dependent alterations of DNA methylation heterogeneity in ageing mouse muscle stem cells. Importantly, promoters with increased methylation heterogeneity are associated with increased transcriptional heterogeneity of the genes they drive. Notably, old cells diverging from young cells revealed alterations in the transcription of multiple extracellular matrix related genes. These findings show linked increases in heterogeneity between the epigenome and the transcriptome, with attendant degradation of coherent transcriptional networks and stem cell functional decline during ageing.