AMP-activated protein kinase is required for exercise-induced peroxisome proliferator-activated receptor γ co-activator 1α translocation to subsarcolemmal mitochondria in skeletal muscle

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master regulator of mitochondrial biogenesis and is controlled, at least in part, through AMP-activated protein kinase and p38-dependent pathways. There is evidence demonstrating that activation of these kinases and induction of PGC-1α in skeletal muscle are regulated by catecholamines. The purpose of the present study was to determine if consumption of a high-fat diet (HFD) impairs epinephrine and 5-aminoimidazole-4-carboxamide-1β-d-ribofuranoside (AICAR) signaling and induction of PGC-1α in rat skeletal muscle. Male Wistar rats were fed chow or a HFD for 6 wk and then given a weight-adjusted bolus injection of epinephrine (20, 10, or 5 μg/100 g body wt sc) or saline, and triceps muscles were harvested 30 min (signaling) or 2 and 4 h (gene expression) postinjection. Despite blunted increases in p38 phosphorylation, the ability of epinephrine to induce PGC-1α was intact in skeletal muscle from HFD-fed rats and was associated with normal increases in activation of PKA and phosphorylation of cAMP response element-binding protein, reputed mediators of PGC-1α expression. The attenuated epinephrine-mediated increase in p38 phosphorylation was independent of increases in MAPK phosphatase 1. At 2 h following AICAR treatment (0.5 g/kg body wt sc), AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation were similar in skeletal muscle from chow- and HFD-fed rats. Surprisingly, AICAR-induced increases in PGC-1α mRNA levels were greater in skeletal muscle from HFD-fed rats. Our results demonstrate that the ability of epinephrine and AICAR to induce PGC-1α remains intact in skeletal muscle from HFD-fed rats. These results question the existence of reduced β-adrenergic responsiveness in diet-induced obesity and demonstrate that increases in p38 phosphorylation are not required for induction of PGC-1α in muscle from obese rats.

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Exercise, PGC-1α, and metabolic adaptation in skeletal muscleThis paper article is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

Applied Physiology Nutrition and Metabolism ◽

10.1139/h09-030 ◽

2009 ◽

Vol 34 (3) ◽

pp. 424-427 ◽

Cited By ~ 13

Author(s):

Zhen Yan

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Peer Review Process ◽

Mitogen Activated Protein Kinase ◽

Metabolic Adaptation ◽

Peroxisome Proliferator ◽

Muscle Adaptation ◽

Peroxisome Proliferator Activated Receptor ◽

Exercise Induced

Endurance exercise promotes skeletal muscle adaptation, and exercise-induced peroxisome proliferator-activated receptor γ coactivator-1α (Pgc-1α) gene expression may play a pivotal role in the adaptive processes. Recent applications of mouse genetic models and in vivo imaging in exercise studies have started to delineate the signaling-transcription pathways that are involved in the regulation of the Pgc-1α gene. These studies revealed the importance of p38 mitogen-activated protein kinase/activating transcription factor 2 and protein kinase D/histone deacetylase 5 signaling transcription axes in exercise-induced Pgc-1α transcription and metabolic adaptation in skeletal muscle. The signaling-transcription network that is responsible for exercise-induced skeletal muscle adaption remains to be fully elucidated.

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Influence of AMP-activated protein kinase and calcineurin on metabolic networks in skeletal muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.90259.2008 ◽

2008 ◽

Vol 295 (3) ◽

pp. E545-E552 ◽

Cited By ~ 28

Author(s):

Yun Chau Long ◽

Juleen R. Zierath

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Protein Kinase ◽

Mitochondrial Gene ◽

Oxidative Capacity ◽

Substrate Utilization ◽

Peroxisome Proliferator ◽

Energy Status ◽

Peroxisome Proliferator Activated Receptor ◽

Amp Activated Protein Kinase

Skeletal muscle fibers differ considerably in their metabolic and physiological properties. Skeletal muscle displays a high degree of metabolic flexibility, which allows the myofibers to adapt to various physiological demands by shifting energy substrate utilization. Transcriptional events play a pivotal role in the metabolic adaptations of skeletal muscle. The expression of genes essential for skeletal muscle glucose and lipid metabolism is tightly coordinated in support of a shift in substrate utilization. AMP-activated protein kinase (AMPK) and calcineurin (a calcium-regulated serine/threonine protein phosphatase) regulate skeletal muscle metabolic gene expression programs in response to changes in the energy status and levels of neuronal input, respectively. AMPK and calcineurin activate transcriptional regulators such as peroxisome proliferator-activated receptor-γ coactivator-1α and myocyte enhancer factor as well as increase skeletal muscle oxidative capacity and mitochondrial gene expression. Activation of either the AMPK or calcineurin pathway can also enhance the glycogen storage capacity and insulin sensitivity in skeletal muscle. Characterization of pathways governing skeletal muscle metabolism offers insight into physiological and pharmacological strategies to prevent or ameliorate peripheral insulin resistance associated with metabolic disorders such as type 2 diabetes.

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Exercise and MEF2–HDAC interactions

Applied Physiology Nutrition and Metabolism ◽

10.1139/h07-082 ◽

2007 ◽

Vol 32 (5) ◽

pp. 852-856 ◽

Cited By ~ 21

Author(s):

Sean L. McGee

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Nuclear Export ◽

Energy Homeostasis ◽

Whole Body ◽

Positive Health ◽

Exercise Induced ◽

Amp Activated Protein Kinase ◽

Body Energy ◽

Skeletal Muscle Adaptations

Exercise increases the metabolic capacity of skeletal muscle, which improves whole-body energy homeostasis and contributes to the positive health benefits of exercise. This is, in part, mediated by increases in the expression of a number of metabolic enzymes, regulated largely at the level of transcription. At a molecular level, many of these genes are regulated by the class II histone deacetylase (HDAC) family of transcriptional repressors, in particular HDAC5, through their interaction with myocyte enhancer factor 2 transcription factors. HDAC5 kinases, including 5′-AMP-activated protein kinase and protein kinase D, appear to regulate skeletal muscle metabolic gene transcription by inactivating HDAC5 and inducing HDAC5 nuclear export. These mechanisms appear to participate in exercise-induced gene expression and could be important for skeletal muscle adaptations to exercise.

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Role of PGC-1α during acute exercise-induced autophagy and mitophagy in skeletal muscle

AJP Cell Physiology ◽

10.1152/ajpcell.00380.2014 ◽

2015 ◽

Vol 308 (9) ◽

pp. C710-C719 ◽

Cited By ~ 131

Author(s):

Anna Vainshtein ◽

Liam D. Tryon ◽

Marion Pauly ◽

David A. Hood

Keyword(s):

Skeletal Muscle ◽

Acute Exercise ◽

Transmembrane Protein ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Lipid Trafficking ◽

Mitochondrial Transcription Factor ◽

Energy Demands ◽

Niemann Pick ◽

Exercise Induced

Regular exercise leads to systemic metabolic benefits, which require remodeling of energy resources in skeletal muscle. During acute exercise, the increase in energy demands initiate mitochondrial biogenesis, orchestrated by the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). Much less is known about the degradation of mitochondria following exercise, although new evidence implicates a cellular recycling mechanism, autophagy/mitophagy, in exercise-induced adaptations. How mitophagy is activated and what role PGC-1α plays in this process during exercise have yet to be evaluated. Thus we investigated autophagy/mitophagy in muscle immediately following an acute bout of exercise or 90 min following exercise in wild-type (WT) and PGC-1α knockout (KO) animals. Deletion of PGC-1α resulted in a 40% decrease in mitochondrial content, as well as a 25% decline in running performance, which was accompanied by severe acidosis in KO animals, indicating metabolic distress. Exercise induced significant increases in gene transcripts of various mitochondrial (e.g., cytochrome oxidase subunit IV and mitochondrial transcription factor A) and autophagy-related (e.g., p62 and light chain 3) genes in WT, but not KO, animals. Exercise also resulted in enhanced targeting of mitochondria for mitophagy, as well as increased autophagy and mitophagy flux, in WT animals. This effect was attenuated in the absence of PGC-1α. We also identified Niemann-Pick C1, a transmembrane protein involved in lysosomal lipid trafficking, as a target of PGC-1α that is induced with exercise. These results suggest that mitochondrial turnover is increased following exercise and that this effect is at least in part coordinated by PGC-1α. Anna Vainshtein received the AJP-Cell 2015 Paper of the Year award. Listen to a podcast with Anna Vainshtein and coauthor David A. Hood at http://ajpcell.podbean.com/e/ajp-cell-paper-of-the-year-2015-award-podcast/ .

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The Importance of Fatty Acids as Nutrients during Post-Exercise Recovery

Nutrients ◽

10.3390/nu12020280 ◽

2020 ◽

Vol 12 (2) ◽

pp. 280 ◽

Cited By ~ 7

Author(s):

Anne-Marie Lundsgaard ◽

Andreas M. Fritzen ◽

Bente Kiens

Keyword(s):

Skeletal Muscle ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Whole Body ◽

Tissue Blood Flow ◽

Peroxisome Proliferator ◽

Early Recovery ◽

Peroxisome Proliferator Activated Receptor ◽

Post Exercise ◽

Exercise Induced

It is well recognized that whole-body fatty acid (FA) oxidation remains increased for several hours following aerobic endurance exercise, even despite carbohydrate intake. However, the mechanisms involved herein have hitherto not been subject to a thorough evaluation. In immediate and early recovery (0–4 h), plasma FA availability is high, which seems mainly to be a result of hormonal factors and increased adipose tissue blood flow. The increased circulating availability of adipose-derived FA, coupled with FA from lipoprotein lipase (LPL)-derived very-low density lipoprotein (VLDL)-triacylglycerol (TG) hydrolysis in skeletal muscle capillaries and hydrolysis of TG within the muscle together act as substrates for the increased mitochondrial FA oxidation post-exercise. Within the skeletal muscle cells, increased reliance on FA oxidation likely results from enhanced FA uptake into the mitochondria through the carnitine palmitoyltransferase (CPT) 1 reaction, and concomitant AMP-activated protein kinase (AMPK)-mediated pyruvate dehydrogenase (PDH) inhibition of glucose oxidation. Together this allows glucose taken up by the skeletal muscles to be directed towards the resynthesis of glycogen. Besides being oxidized, FAs also seem to be crucial signaling molecules for peroxisome proliferator-activated receptor (PPAR) signaling post-exercise, and thus for induction of the exercise-induced FA oxidative gene adaptation program in skeletal muscle following exercise. Collectively, a high FA turnover in recovery seems essential to regain whole-body substrate homeostasis.

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