title: Tumor necrosis factor-alpha inhibits myogenesis through redox-dependent and -independent pathways.
abstract: Muscle wasting accompanies diseases that are associated with chronic elevated levels of circulating inflammatory cytokines and oxidative stress. We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) inhibits myogenic differentiation via the activation of nuclear factor-kappaB (NF-kappaB). The goal of the present study was to determine whether this process depends on the induction of oxidative stress. We demonstrate here that TNF-alpha causes a decrease in reduced glutathione (GSH) during myogenic differentiation of C(2)C(12) cells, which coincides with an elevated generation of reactive oxygen species. Supplementation of cellular GSH with N-acetyl-l-cysteine (NAC) did not reverse the inhibitory effects of TNF-alpha on troponin I promoter activation and only partially restored creatine kinase activity in TNF-alpha-treated cells. In contrast, the administration of NAC before treatment with TNF-alpha almost completely restored the formation of multinucleated myotubes. NAC decreased TNF-alpha-induced activation of NF-kappaB only marginally, indicating that the redox-sensitive component of the inhibition of myogenic differentiation by TNF-alpha occurred independently, or downstream of NF-kappaB. Our observations suggest that the inhibitory effects of TNF-alpha on myogenesis can be uncoupled in a redox-sensitive component affecting myotube formation and a redox independent component affecting myogenic protein expression.
authors.affiliation: Department of Pulmonology, Maastricht University, The Netherlands.
authors.forename: Ramon C J
authors.initials: RC
authors.lastname: Langen
authors.forename: Annemie M W J
authors.initials: AM
authors.lastname: Schols
authors.forename: Marco C J M
authors.initials: MC
authors.lastname: Kelders
authors.forename: Jos L J
authors.initials: JL
authors.lastname: Van Der Velden
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
authors.forename: Yvonne M W
authors.initials: YM
authors.lastname: Janssen-Heininger
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D003402:Creatine Kinase / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D051379:Mice; D024510:Muscle Development / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D003402:Creatine Kinase; D005978:Glutathione; D000111:Acetylcysteine