Aerobic Exercise Preserves Skeletal Muscle Function in Middle-Aged Mice Through the miR-150-5p/miR-199a-5p–Wnt/FZD4 Signaling Pathway

MicroRNAs are important regulators of skeletal muscle development and regeneration; however, the molecular basis by which exercise-induced miRNAs preserve middle-aged muscle function remains to be elucidated. This study aimed to investigate how aerobic exercise delays skeletal muscle attenuation by reversing age-related miRNAs dysregulation in male mice. Twelve-month-old male C57BL/6J mice (MC) (n = 8/group) were randomly assigned to a sedentary control group (OC) or an aerobic exercise group (OE) (12 m/min, 40 min/session, three sessions/week, for 12 weeks). miRNA sequencing identified differentially expressed miRNAs (DEmiRNAs), followed by miRNA–mRNA network construction. The results demonstrated that aerobic exercise improved muscle strength and mass while attenuating early atrophy and fibrosis. Four atrophy-associated DEmiRNAs (miR-150-5p, miR-199a-5p, miR-3535, and miR-329-5p) were reversed after aerobic exercise intervention. GO and KEGG profiling demonstrated that target genes were predominantly involved in protein binding and the Wnt signaling pathway. miR-199a-5p and miR-150-5p, with the most predicted targets, were selected as candidate mechanistic contributors, and FZD4 was confirmed as a common downstream target. Further analysis confirmed that miR-199a-5p and miR-150-5p inhibition attenuated D-galactose-induced C2C12 myotube atrophy, reducing Atrogin-1 and increasing MyoD1, FZD4, and β-catenin expression. These findings suggest that the exercise-induced miR-150-5p/miR-199a-5p axis may alleviate muscle aging in middle age via the restoration of key proteins in Wnt signaling and contribute preliminary observational evidence relevant to the understanding of aerobic exercise intervention in sarcopenia.