title: Interactions between ROS and AMP kinase activity in the regulation of PGC-1alpha transcription in skeletal muscle cells.
abstract: Reactive oxygen species (ROS) play an important role in cellular function via the activation of signaling cascades. ROS have been shown to affect mitochondrial biogenesis, morphology, and function. Their beneficial effects are likely mediated via the upregulation of transcriptional regulators such as peroxisome proliferator-activated receptor-gamma coactivator-1 protein-alpha (PGC-1alpha). However, the ROS signals that regulate PGC-1alpha transcription in skeletal muscle are not understood. Here we examined the effect of H2O2 on the regulation of PGC-1alpha expression, and its relationship to AMPK activation. We demonstrate that 24 h of exogenous H2O2 treatment increased PGC-1alpha promoter activity and mRNA expression. Both effects were blocked with the addition of N-acetylcysteine, a ROS scavenger. These effects were mediated, in part, via upstream stimulatory factor-1/Ebox DNA binding and involved 1) interactions with downstream sequences and 2) the activation of AMPK. Elevated ROS led to the activation of AMPK, likely via a decline in ATP levels. The activation of AMPK using 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside increased PGC-1alpha promoter activity and mRNA levels but reduced ROS production. Thus the net effect of AMPK activation on PGC-1alpha expression was a result of increased transcriptional activation, counterbalanced by reduced ROS production. The effects of H2O2 on PGC-1alpha expression differed depending on the level of ROS within the cell. Low levels of ROS result in reduced PGC-1alpha mRNA in the absence of an effect on PGC-1alpha promoter activation. In contrast, elevated levels of H2O2 induce PGC-1alpha transcription indirectly, via AMPK activation. These data identify unique interactions between ROS and AMPK activation on the expression of PGC-1alpha in muscle cells.
authors.affiliation: School of Kinesiology and Health Science, Rm. 302, Farquharson Life Sciences Bldg., York University, 4700 Keele St., Toronto, ON, Canada M3J 1P3.
authors.forename: Isabella
authors.initials: I
authors.lastname: Irrcher
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ljubicic
authors.forename: David A
authors.initials: DA
authors.lastname: Hood
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000111:Acetylcysteine / Q000494:pharmacology; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D024721:E-Box Elements; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000201:enzymology*; D016877:Oxidants / Q000494:pharmacology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012265:Ribonucleotides / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D051720:Upstream Stimulatory Factors / Q000378:metabolism
chemical_list: D020536:Enzyme Activators; D016166:Free Radical Scavengers; D016877:Oxidants; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012265:Ribonucleotides; D015534:Trans-Activators; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; C497183:Usf1 protein, mouse; D000620:Aminoimidazole Carboxamide; D006861:Hydrogen Peroxide; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D000111:Acetylcysteine