title: Acute Endurance Exercise Induces Nuclear p53 Abundance in Human Skeletal Muscle.
abstract: OBJECTIVE
  The tumor suppressor protein p53 may have regulatory roles in exercise response-adaptation processes such as mitochondrial biogenesis and autophagy, although its cellular location largely governs its biological role. We investigated the subcellular localization of p53 and selected signaling targets in human skeletal muscle following a single bout of endurance exercise.
  
  
  METHODS
  Sixteen, untrained individuals were pair-matched for aerobic capacity (VO2peak) and allocated to either an exercise (EX, n = 8) or control (CON, n = 8) group. After a resting muscle biopsy, EX performed 60 min continuous cycling at ~70% of VO2peak during which time CON subjects rested. A further biopsy was obtained from both groups 3 h post-exercise (EX) or 4 h after the first biopsy (CON).
  
  
  RESULTS
  Nuclear p53 increased after 3 h recovery with EX only (~48%, p < 0.05) but was unchanged in the mitochondrial or cytoplasmic fractions in either group. Autophagy protein 5 (Atg-5) decreased in the mitochondrial protein fraction 3 h post-EX (~69%, P < 0.05) but remained unchanged in CON. There was an increase in cytoplasmic levels of the mitophagy marker PINK1 following 3 h of rest in CON only (~23%, P < 0.05). There were no changes in mitochondrial, nuclear, or cytoplasmic levels of PGC-1α post-exercise in either group.
  
  
  CONCLUSIONS
  The selective increase in nuclear p53 abundance following endurance exercise suggests a potential pro-autophagy response to remove damaged proteins and organelles prior to initiating mitochondrial biogenesis and remodeling responses in untrained individuals.
authors.affiliation: Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University Melbourne, VIC, Australia.
authors.forename: Bill
authors.initials: B
authors.lastname: Tachtsis
authors.affiliation: Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University Melbourne, VIC, Australia.
authors.forename: William J
authors.initials: WJ
authors.lastname: Smiles
authors.affiliation: Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University Melbourne, VIC, Australia.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Lane
authors.affiliation: Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic UniversityMelbourne, VIC, Australia; Research Institute for Sport and Exercise Sciences, Liverpool John Moores UniversityLiverpool, UK.
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
authors.affiliation: Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic UniversityMelbourne, VIC, Australia; Exercise and Nutrition Research Group, School of Medical Sciences, RMIT UniversityMelbourne, VIC, Australia.
authors.forename: Donny M
authors.initials: DM
authors.lastname: Camera
keywords: autophagy; cell signaling; mitochondrial biogenesis; mitochondrial turnover; skeletal muscle