title: Transforming growth factor type beta (TGF-β) requires reactive oxygen species to induce skeletal muscle atrophy.
abstract: Transforming growth factor beta 1 (TGF-β1) is a classical modulator of skeletal muscle and regulates several processes, such as myogenesis, regeneration, and muscle function in skeletal muscle diseases. Skeletal muscle atrophy, characterised by the loss of muscle strength and mass, is one of the pathological conditions regulated by TGF-β. Atrophy also results in increased myosin heavy chain (MHC) degradation and the expression of two muscle-specific E3 ubiquitin ligases, atrogin-1 and MuRF-1. Reactive oxygen species (ROS) are modulators of muscle wasting, and NAD(P)H oxidase (NOX) is one of the main sources of ROS. While it was recently found that TGF-β1 induces atrophy in skeletal muscle, the underlying mechanism is not fully understood. In this study, the role of NOX-derived ROS in skeletal muscle atrophy induced by TGF-β was assessed. TGF-β1 induced an atrophic effect in C2C12 myotubes, as evidenced by decreased myotube diameter and MHC levels, together with increased MuRF-1 levels. Concomitantly, TGF-β increased NOX-induced ROS contents. Interestingly, NOX inhibition through apocynin and the antioxidant treatment with N-acetyl cysteine (NAC) decreased increased ROS levels in myotubes. Additionally, both apocynin and NAC completely prevented the decreased MHC, decreased myotube diameter, and increased MuRF-1 induced by TGF-β. Injection of TGF-β1 into the tibialis anterior muscle induced atrophy, as observed by decreased fibre diameter and MHC levels, together with increased MuRF-1 levels. Likewise, TGF-β increased the ROS contents in the smaller fibres of skeletal muscle. Additionally, the administration of NAC to mice prevented all atrophic effects and the increase in ROS induced by TGF-β in the tibialis anterior. This is the first study to report that TGF-β has an atrophic effect dependent on NOX-induced ROS in skeletal muscle.
authors.affiliation: Laboratory of Biology and Molecular Physiopathology, Department of Biological Sciences, Faculty of Biological Sciences, Faculty of Medicine, Universidad Andrés Bello, Santiago, Chile; Millennium Institute on Immunology and Immunotherapy, Santiago, Chile.
authors.forename: Johanna
authors.initials: J
authors.lastname: Abrigo
authors.affiliation: Laboratory of Biology and Molecular Physiopathology, Department of Biological Sciences, Faculty of Biological Sciences, Faculty of Medicine, Universidad Andrés Bello, Santiago, Chile; Millennium Institute on Immunology and Immunotherapy, Santiago, Chile.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Rivera
authors.affiliation: Millennium Institute on Immunology and Immunotherapy, Santiago, Chile; Laboratory of Integrative Physiopathology, Department of Biological Sciences, Faculty of Biological Sciences, Faculty of Medicine, Universidad Andrés Bello, Santiago, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Simon
authors.affiliation: Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Departamento de Ciencias Químicas y Biológicas, Facultad de Salud, Universidad Bernardo O Higgins, Santiago, Chile.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cabrera
authors.affiliation: Laboratory of Biology and Molecular Physiopathology, Department of Biological Sciences, Faculty of Biological Sciences, Faculty of Medicine, Universidad Andrés Bello, Santiago, Chile; Millennium Institute on Immunology and Immunotherapy, Santiago, Chile. Electronic address: claudio.cabello@unab.cl.
authors.forename: Claudio
authors.initials: C
authors.lastname: Cabello-Verrugio
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001284:Atrophy; D002460:Cell Line; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000648:ultrastructure; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D019255:NADPH Oxidases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000502:physiology* / Q000633:toxicity; D000070584:Tripartite Motif Proteins / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D000975:Antioxidants; D009124:Muscle Proteins; D017382:Reactive Oxygen Species; D053773:Transforming Growth Factor beta1; D000070584:Tripartite Motif Proteins; D019255:NADPH Oxidases; C499084:Trim63 protein, mouse; D044767:Ubiquitin-Protein Ligases
keywords: MHC; MuRF-1; Muscle wasting; NOX; ROS; TGF-β