A Rejuvenation Signature in Skeletal Muscle That Is Mediated By Late-Life Exercise

Abstract

The objectives of this study were to measure to what extent exercise stimulates partial molecular reprogramming in skeletal muscle. We hypothesized that exercise training, beyond its known functional improvements in aged tissues, could recapitulate some of the same effects that are seen with in vivo partial reprogramming by Yamanaka factors. Using transcriptome profiling from 1) a skeletal muscle-specific in vivo Oct3/4, Klf4, Sox2, and Myc (OKSM) reprogramming-factor expression murine model, 2) an in vivo inducible muscle-specific Myc induction murine model, 3) a translatable high-volume hypertrophic exercise training approach in aged mice, and 4) human exercise muscle biopsies, we collectively defined exercise-induced genes common to partial reprogramming. Late-life exercise training lowered murine DNA methylation age according to several contemporary muscle-specific clocks. A comparison of the murine soleus transcriptome after late-life exercise training to the soleus transcriptome after OKSM induction revealed an overlapping signature. Within this signature, downregulation of specific mitochondrial and muscle-enriched genes was conserved in skeletal muscle of long-term exercise-trained humans; among these was muscle-specific Abra/Stars. Myc is the OKSM factor most induced by exercise in muscle and was elevated following exercise training in aged mice. A pulse of MYC rewired the global soleus muscle methylome, and the transcriptome after a MYC pulse partially recapitulated OKSM induction. A common signature also emerged in the murine MYC-controlled and exercise adaptation transcriptomes, including lower muscle-specific Melusin and reactive oxygen species-associated Romo1. With Myc, OKSM, and exercise training in mice as well habitual exercise in humans, the complex I accessory subunit Ndufb11 was lower; low Ndufb11 is linked to longevity in rodents. Our data collectively suggest: 1) a biological age-mitigating effect on the epigenetic landscape by late-life exercise-training in murine skeletal muscle, 2) a common gene expression signature of partial reprogramming by OKSM and exercise training in muscle of humans and aged mice, and 3) that Myc is an exercise-responsive factor that contributes to a rewired molecular profile at the transcriptome and methylome levels. National Institutes of Health: Kevin A. Murach, AG063994; American Federation for Aging Research (AFAR): Kevin A. Murach, Junior Investigator Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.