Aging triggers H3K27 trimethylation hoarding in the chromatin of Nothobranchius furzeri skeletal muscle.

Aging associates with progressive loss of skeletal muscle function leading up to sarcopenia, a process characterized by impaired mobility and weaken muscle strength. Sarcopenia underpinning molecular mechanisms are still poorly characterized. Since, aging associates with profound epigenetic changes, the investigation of the epigenetic landscape alteration in the skeletal muscle promises to highlight molecular mechanisms of age-associated sarcopenia. Here, the study was conducted exploiting the short-lived Nothobranchius furzeri (Nfu), a relatively new model for aging studies. The epigenetic analysis suggested for a less accessible and more condensed chromatin in old Nfu skeletal muscle. Specifically, an accumulation of heterochromatin regions was observed as consequence of increased levels of H3K27me3, HP1a, polycomb complex subunit expression and SAHFs. Consistently, euchromatin histone marks, including H3K9ac, decreased. The integrative bioinformatics analysis of RNASeq and ChIPSeq dataset, related to skeletal muscle of Nfu at different ages, revealed a down-modulation of transcripts involved in cell cycle, differentiation and DNA repair and an up-regulation of inflammation and senescence genes. Undoubtedly, more studies are needed to disclose the detailed mechanisms, but this approach shed light on unprecedented specific features of Nfu skeletal muscle aging, responsible of sarcopenia onset and consequent impairment of swimming and mobility activity typical of old Nfu. Overall design: Skeletal muscle derived from Nothobranchius furzeri at different ages: 5 weeks, 20 weeks and 35 weeks (n=3 for each age)