Niels Jessen

Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle

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Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser(555) stimulates autophagy whereas phosphorylation at Ser(757) is inhibitory. To determine if exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1 hour cycling exercise at 50% VO2-max on two occasions: 1) during a 36 hour fast and 2) during continuous glucose infusion at 0.2 g/kg/h. Physical exercise increased ULK1 phosphorylation at Ser(555) and decreased lipidation of Light Chain 3B (LC3B). ULK1 phosphorylation at Ser(555) correlated positively with AMPKα Thr(172) phosphorylation and negatively with LC3B lipidation. ULK1 phosphorylation at Ser(757) was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 minutes of exercise independently of nutritional status and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.

TidsskriftJournal of Applied Physiology
Sider (fra-til)971-9
Antal sider9
StatusUdgivet - 15 apr. 2015

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