title: Cytoprotective Role of Nrf2 in Electrical Pulse Stimulated C2C12 Myotube.
abstract: Regular physical exercise is central to a healthy lifestyle. However, exercise-related muscle contraction can induce reactive oxygen species and reactive nitrogen species (ROS/RNS) production in skeletal muscle. The nuclear factor-E2-related factor-2 (Nrf2) transcription factor is a cellular sensor for oxidative stress. Regulation of nuclear Nrf2 signaling regulates antioxidant responses and protects organ structure and function. However, the role of Nrf2 in exercise- or contraction-induced ROS/RNS production in skeletal muscle is not clear. In this study, using differentiated C2C12 cells and electrical pulse stimulation (EPS) of muscle contraction, we explored whether Nrf2 plays a role in the skeletal muscle response to muscle contraction-induced ROS/RNS. We found that EPS (40 V, 1 Hz, 2 ms) stimulated ROS/RNS accumulation and Nrf2 activation. We also showed that expression of NQO1, HO-1 and GCLM increased after EPS-induced muscle contraction and was remarkably suppressed in cells with Nrf2 knockdown. We also found that the antioxidant N-acetylcysteine (NAC) significantly attenuated Nrf2 activation after EPS, whereas the nitric oxide synthetase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) did not. Furthermore, Nrf2 knockdown after EPS markedly decreased ROS/RNS redox potential and cell viability and increased expression of the apoptosis marker Annexin V in C2C12 myotubes. These results indicate that Nrf2 activation and expression of Nrf2 regulated-genes protected muscle against the increased ROS caused by EPS-induced muscle contraction. Thus, our findings suggest that Nrf2 may be a key factor for preservation of muscle function during muscle contraction.
authors.affiliation: Division of Medical Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.|Japan Society for the Promotion of Science, Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Horie
authors.affiliation: Division of Biomedical Sciences, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Warabi
authors.affiliation: Graduate School of Comprehensive Human Sciences Majors of Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Komine
authors.affiliation: Division of Medical Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.|Japan Society for the Promotion of Science, Tokyo, Japan.
authors.forename: Sechang
authors.initials: S
authors.lastname: Oh
authors.affiliation: Division of Medical Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Shoda
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D019610:Cytoprotection; D004558:Electric Stimulation; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000975:Antioxidants; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species