Glycogen Content Regulates Peroxisome Proliferator Activated Receptor-∂ (PPAR-∂) Activity in Rat Skeletal Muscle

Andrew Philp, Matthew G MacKenzie, Micah Y Belew, Mhairi C Towler, Alan Corstorphine, Angela Papalamprou, D Grahame Hardie, Keith Baar (Lead / Corresponding author)

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    138 Downloads (Pure)

    Abstract

    Performing exercise in a glycogen depleted state increases skeletal muscle lipid utilization and the transcription of genes regulating mitochondrial β-oxidation. Potential candidates for glycogen-mediated metabolic adaptation are the peroxisome proliferator activated receptor (PPAR) coactivator-1α (PGC-1α) and the transcription factor/nuclear receptor PPAR-∂. It was therefore the aim of the present study to examine whether acute exercise with or without glycogen manipulation affects PGC-1α and PPAR-∂ function in rodent skeletal muscle. Twenty female Wistar rats were randomly assigned to 5 experimental groups (n = 4): control [CON]; normal glycogen control [NG-C]; normal glycogen exercise [NG-E]; low glycogen control [LG-C]; and low glycogen exercise [LG-E]). Gastrocnemius (GTN) muscles were collected immediately following exercise and analyzed for glycogen content, PPAR-∂ activity via chromatin immunoprecipitation (ChIP) assays, AMPK α1/α2 kinase activity, and the localization of AMPK and PGC-1α. Exercise reduced muscle glycogen by 47 and 75% relative to CON in the NG-E and LG-E groups, respectively. Exercise that started with low glycogen (LG-E) finished with higher AMPK-α2 activity (147%, p<0.05), nuclear AMPK-α2 and PGC-1α, but no difference in AMPK-α1 activity compared to CON. In addition, PPAR-∂ binding to the CPT1 promoter was significantly increased only in the LG-E group. Finally, cell reporter studies in contracting C2C12 myotubes indicated that PPAR-∂ activity following contraction is sensitive to glucose availability, providing mechanistic insight into the association between PPAR-∂ and glycogen content/substrate availability. The present study is the first to examine PPAR-∂ activity in skeletal muscle in response to an acute bout of endurance exercise. Our data would suggest that a factor associated with muscle contraction and/or glycogen depletion activates PPAR-∂ and initiates AMPK translocation in skeletal muscle in response to exercise.

    Original languageEnglish
    Pages (from-to)e77200
    JournalPLoS ONE
    Volume8
    Issue number10
    DOIs
    Publication statusPublished - 17 Oct 2013

    Keywords

    • AMP-Activated Protein Kinases
    • Animals
    • Cell Line
    • Enzyme Activation
    • Female
    • Glucose
    • Glycogen
    • Muscle, Skeletal
    • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
    • Peroxisome Proliferator-Activated Receptors
    • Physical Conditioning, Animal
    • Rats
    • Transcription Factors
    • Journal Article
    • Research Support, Non-U.S. Gov't

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