title: PGC-1{alpha} is required for AICAR-induced expression of GLUT4 and mitochondrial proteins in mouse skeletal muscle.
abstract: We tested the hypothesis that repeated activation of AMP-activated protein kinase (AMPK) induces mitochondrial and glucose membrane transporter mRNA/protein expression via a peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha)-dependent mechanism. Whole body PGC-1alpha-knockout (KO) and littermate wild-type (WT) mice were given either single or repeated subcutaneous injections of the AMPK activator AICAR or saline. Skeletal muscles were removed either 1 or 4 h after the single AICAR treatment or 24 h after the last injection following repeated AICAR treatment. Repeated AICAR treatment increased GLUT4, cytochrome (cyt) c oxidase I, and (cyt) c protein expression approximately 10-40% relative to saline in white muscles of WT but not of PGC-1alpha-KO mice, whereas fatty acid translocase/CD36 (FAT/CD36) protein expression was unaffected by AICAR treatment in both genotypes. GLUT4, cyt c, and FAT/CD36 mRNA content increased 30-60% 4 h after a single AICAR injection relative to saline in WT, and FAT/CD36 mRNA content decreased in PGC-1alpha-KO mice. One hour after a single AICAR treatment, phosphorylation of AMPK and the downstream target acetyl-coenzyme A carboxylase increased in all muscles investigated independent of genotype, indicating normal AICAR-induced AMPK signaling in the absence of PGC-1alpha. The hexokinase II (HKII) mRNA and protein response was similar in muscles of WT and PGC-1alpha-KO mice after single and repeated AICAR treatments, respectively, confirming that HKII is regulated independently of PGC-1alpha in response to AICAR. In conclusion, here we provide genetic evidence for a role of PGC-1alpha in AMPK-mediated regulation of mitochondrial and glucose membrane transport protein expression in skeletal muscle.
authors.affiliation: Centre of Inflammation and Metabolism and Copenhagen Muscle Research Centre, Department of Biology, Univ. of Copenhagen, Denmark.
authors.forename: Lotte
authors.initials: L
authors.lastname: Leick
authors.forename: Joachim
authors.initials: J
authors.lastname: Fentz
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Biensø
authors.forename: Jakob G
authors.initials: JG
authors.lastname: Knudsen
authors.forename: Jacob
authors.initials: J
authors.lastname: Jeppesen
authors.forename: Bente
authors.initials: B
authors.lastname: Kiens
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
authors.forename: Henriette
authors.initials: H
authors.lastname: Pilegaard
mesh_terms: D000263:Adenylate Kinase / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005260:Female; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012265:Ribonucleotides / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors
chemical_list: D001786:Blood Glucose; D018955:CD36 Antigens; D051275:Glucose Transporter Type 4; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D012265:Ribonucleotides; D015534:Trans-Activators; D014157:Transcription Factors; D000620:Aminoimidazole Carboxamide; D006003:Glycogen; D003576:Electron Transport Complex IV; D000263:Adenylate Kinase; C031143:AICA ribonucleotide