title: Calcium induces increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha and mitochondrial biogenesis by a pathway leading to p38 mitogen-activated protein kinase activation.
abstract: Previous studies have shown that raising cytosolic calcium in myotubes induces increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha expression and mitochondrial biogenesis. This finding suggests that the increases in cytosolic calcium in skeletal muscle during exercise may mediate the exercise-induced increase in mitochondria. The initial aim of this study was to determine whether raising calcium in skeletal muscle induces the same adaptations as in myotubes. We found that treatment of rat epitrochlearis muscles with a concentration of caffeine that raises cytosolic calcium to a concentration too low to cause contraction induces increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha expression and mitochondrial biogenesis. Our second aim was to elucidate the pathway by which calcium induces these adaptations. Raising cytosolic calcium has been shown to activate calcium/calmodulin-dependent protein kinase in muscle. In the present study raising cytosolic calcium resulted in increases in phosphorylation of p38 mitogen-activated protein kinase and activating transcription factor-2, which were blocked by the calcium/calmodulin-dependent protein kinase inhibitor KN93 and by the p38 mitogen-activated protein kinase inhibitor SB202190. The increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha expression and mitochondrial biogenesis were also prevented by inhibiting p38 activation. We interpret these findings as evidence that p38 mitogen-activated protein kinase is downstream of calcium/calmodulin-dependent protein kinase in a signaling pathway by which increases in cytosolic calcium lead to increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha expression and mitochondrial biogenesis in muscle.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Wright
authors.forename: Paige C
authors.initials: PC
authors.lastname: Geiger
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Han
authors.forename: Terry E
authors.initials: TE
authors.lastname: Jones
authors.forename: John O
authors.initials: JO
authors.lastname: Holloszy
mesh_terms: D000199:Actins / Q000378:metabolism; D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000199:Actins; D051698:Activating Transcription Factor 2; C497107:Atf2 protein, rat; D015415:Biomarkers; D004791:Enzyme Inhibitors; D006360:Heat-Shock Proteins; D007093:Imidazoles; D047495:PPAR gamma; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011725:Pyridines; D014157:Transcription Factors; D017868:Cyclic AMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; D002118:Calcium