Loss of ARNT Impair Adaptability of Muscular Exercise in Aged Mice

The adaptation of regimented exercise in skeletal muscle including muscular hypertrophy and enhanced strength decline significantly with aging. Transcriptome analysis following RNA sequencing reveals extensive activation of hypoxia-related genes in young exercised mice versus the sedentary, but absent in aged exercised mice. Particularly, less expression of aryl hydrocarbon receptor translocator (ARNT) was observed in response to exercise in aged mice. Young mice underwent skeletal muscle-specific knockout of ARNT (ARNT mKO) obtain deficient benefit from exercise resembling the aged mice. The deletion of ARNT associated with decreased expression of Notch1 intracellular domain(N1ICD) impair muscle hypertrophy and regeneration. Administration of ML228, a systematic agonist of ARNT, rescued skeletal muscle adaptabilities in old mice, which was suppressed by administrating N1ICD inhibitor(DAPT). These results suggest that the loss of skeletal muscle ARNT is partially responsible for diminished response to exercise in aging and activation of hypoxia signaling holds promise for rescuing the adaptability in aged muscle. Quadriceps femoris mRNA profile of young and old mice subjected to 8 weeks of treadmill running exercise regimen or sedentary activity