Human myofiber-enriched aging-induced lncRNA FRAIL1 promotes muscle atrophy
The loss of skeletal muscle mass during aging is a significant health concern linked to adverse outcomes in older individuals. Understanding the molecular basis of age-related muscle loss is crucial for developing strategies to prevent or reverse this debilitating condition. Long non-coding RNAs (lncRNAs) are a largely uncharacterized class of biomolecules that have been implicated in cellular homeostasis and dysfunction across a wide variety of tissues and cell types. To identify lncRNAs that might contribute to skeletal muscle aging we screened for lncRNAs whose expression was altered in vastus lateralis muscle from older compared to young adults. We identified FRAIL1 as an aging-induced lncRNA with high abundance in human skeletal muscle. In a cohort of healthy young and older adults, skeletal muscle FRAIL1 was most strongly expressed in older females and negatively associated with measures of muscle strength and mass. Forced expression of FRAIL1 in mouse tibialis anterior muscle elicits a dose-dependent reduction in skeletal muscle fiber size that is independent of changes in muscle fiber type. Furthermore, this reduction in muscle size is dependent on an intact region of FRAIL1 that is highly conserved across non-human primates. Unbiased transcriptional and proteomic profiling of the effects of FRAIL1 expression in mouse skeletal muscle revealed widespread changes in mRNA and protein abundance that recapitulate age-related changes in pathways and processes that are known to be altered in aging skeletal muscle. Taken together, these findings shed light on the intricate molecular mechanisms underlying skeletal muscle aging and implicate FRAIL1 in the reduction of muscle mass during this process. Overall design: One tibialis anterior (TA) muscle per mouse (n=6) was transfected with 10 µg of empty plasmid (pcDNA3), and the contralateral TA in each mouse was transfected with 10 µg of full length human FRAIL1 lncRNA expressing plasmid. Seven days post-transfection, bilateral TAs were harvested and subjected to RNA-seq analysis.