Transcriptional Diversity in Response to Aging Across Skeletal Muscles.

Aging leads to a gradual decline in muscle function, yet the mechanisms by which different skeletal muscles respond to aging remain unclear. Here, we constructed transcriptional maps of 11 skeletal muscles with extensive transcriptional diversity from young and old mice. Age-related changes in gene expression displayed distinct tissue-specific patterns, involving muscle diseases and metabolic processes. Notably, the mitochondrial-enriched soleus muscle exhibited superior resistance to aging compared to other skeletal muscles. Further, we generated a single-nuclei transcriptomic atlas on representative skeletal muscles, analyzing 73,170 nuclei. We found the age-related changes in the cellular composition of different skeletal muscles and the emergence of new cell states in aged mice. Among different types of myonuclei, type II myonuclei showed particular sensitivity to aging, with reduced metabolic activity of IIb myonuclei with age. We also found cell-specific changes occurring across nonmuscle nuclei populations, including adipocytes, fibro-adipogenic progenitors, and immune cells, accelerating muscle aging and associated pathologies. Intercellular communication analysis revealed more intensive intercellular interactions in aged skeletal muscles, particularly between myonuclei and other cell types. Specifically, we validated the regulatory role of the EGF/EGFR axis in age-related inflammatory processes. These findings provide insight into muscle biology and aging and highlight potential therapeutic targets for age-associated muscle disorders.