Autophagy contributes to remodeling of skeletal muscle and is sensitive to contractile activity and prevailing energy availability. We investigated changes in targeted genes and proteins with roles in autophagy following 5 days of energy balance (EB), energy deficit (ED), and resistance exercise (REX) after ED. Muscle biopsies from 15 subjects (8 males, 7 females) were taken at rest following 5 days of EB [45 kcal·kg fat free mass (FFM)-1·day-1] and 5 days of ED (30 kcal·kg FFM-1·day-1). After ED, subjects completed a bout of REX and consumed either placebo (PLA) or 30 g whey protein (PRO) immediately postexercise. Muscle biopsies were obtained at 1 and 4 h into recovery in each trial. Resting protein levels of autophagy-related gene protein 5 (Atg5) decreased after ED compared with EB (~23%, P <0.001) and remained below EB from 1 to 4 h postexercise in PLA (~17%) and at 1 h in PRO (~18%, P <0.05). In addition, conjugated Atg5 (cAtg12) decreased below EB in PLA at 4 h (~20, P <0.05); however, its values were increased above this time point in PRO at 4 h alongside increases in FOXO1 above EB (~22–26%, P<0.05). Notably, these changes were subsequent to increases in unc-51-like kinase 1Ser757 phosphorylation (~60%) 1 h postexercise in PRO. No significant changes in gene expression of selected autophagy markers were found, but EGR-1 increased above ED and EB in PLA (~417–864%) and PRO (~1,417–2,731%) trials 1 h postexercise (P<0.001). Postexercise protein availability, compared with placebo, can selectively promote autophagic responses to REX in ED.
|Number of pages||10|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|Publication status||Published - 3 Sep 2015|