title: Hydrogen peroxide stimulates ubiquitin-conjugating activity and expression of genes for specific E2 and E3 proteins in skeletal muscle myotubes.
abstract: Reactive oxygen species (ROS) are thought to promote muscle atrophy in chronic wasting diseases, but the underlying mechanism has not been determined. Here we show that H2O2 stimulates ubiquitin conjugation to muscle proteins through transcriptional regulation of the enzymes (E2 and E3 proteins) that conjugate ubiquitin to muscle proteins. Incubation of C2C12 myotubes with 100 microM H2O2 increased the rate of 125I-labeled ubiquitin conjugation to muscle proteins in whole cell extracts. This response required at least 4-h exposure to H2O2 and persisted for at least 24 h. Preincubating myotubes with cycloheximide or actinomycin D blocked H2O2 stimulation of ubiquitin-conjugating activity, suggesting that gene transcription is required. Northern blot analyses revealed that H2O2 upregulates expression of specific E3 and E2 proteins that are thought to regulate muscle catabolism, including atrogin1/MAFbx, MuRF1, and E214k. These results suggest that ROS stimulate protein catabolism in skeletal muscle by upregulating the ubiquitin conjugation system.
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Li
authors.forename: Yuling
authors.initials: Y
authors.lastname: Chen
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Li
authors.forename: Michael B
authors.initials: MB
authors.lastname: Reid
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008025:Ligases / Q000235:genetics*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics*; D018482:Muscle, Skeletal / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology*; D044843:SKP Cullin F-Box Protein Ligases; D000070584:Tripartite Motif Proteins; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D009124:Muscle Proteins; D016877:Oxidants; D000070584:Tripartite Motif Proteins; D014452:Ubiquitins; D006861:Hydrogen Peroxide; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C440907:FBXO32 protein, human; C486691:Fbxo32 protein, mouse; D044843:SKP Cullin F-Box Protein Ligases; C440908:TRIM63 protein, human; C499084:Trim63 protein, mouse; D044767:Ubiquitin-Protein Ligases; D008025:Ligases