GSE185707
A hyper-quiescent chromatin state is a barrier to productive regeneration during aging. [DNA-Seq]
Epigenetic alterations are one of the key hallmarks of aging. Emerging evidence in model organisms, senescent cell cultures and limitedly, murine, and human tissue samples suggest local effects impacting genes and regulatory elements. However, how chromatin changes broadly affect euchromatin-heterochromatin balance, three-dimensional chromatin conformation, histone composition and global transcriptome has not been addressed. Furthermore, the cause and impact of these alterations on tissue function and age-related loss of regeneration is not well-understood. Here, using murine liver as a model for regeneration and an integrated multi-omics approach, we find that aged cells assume a severely repressed hyper-quiescent chromatin state characterized by a condensed chromatin, broad heterochromatinization driven by H3K27me3, global suppression of the transcriptome and inability of the chromatin to self-interact over long distances. Interestingly, concomitant targeted chromatin opening occurs over developmental gene promoters leading to loss of cell identity. We extend our findings to other quiescent tissues including human liver biopsies. Our findings reveal that global chromatin alterations promote a cellular state that is refractory to injury sensing and repair. Local chromatin changes compromise cellular identity. Together, this study provides possible explanations for age-related loss of regeneration and tissue function at the chromatin level. Overall design: DNA-seq of chromatin eluted at different salt concentrations. n= 2 replicates per group.