title: Cobalt triggers necrotic cell death and atrophy in skeletal C2C12 myotubes.
abstract: Severe poisoning has recently been diagnosed in humans having hip implants composed of cobalt-chrome alloys due to the release of particulate wear debris on polyethylene and ceramic implants which stimulates macrophagic infiltration and destroys bone and soft tissue, leading to neurological, sensorial and muscular impairments. Consistent with this premise, in this study, we focused on the mechanisms underlying the toxicity of Co(II) ions on skeletal muscle using mouse skeletal C2C12 myotubes as an in vitro model. As detected using propidium iodide incorporation, increasing CoCl2 doses (from 5 to 200μM) affected the viability of C2C12 myotubes, mainly by cell necrosis, which was attenuated by necrostatin-1, an inhibitor of the necroptotic branch of the death domain receptor signaling pathway. On the other hand, apoptosis was hardly detectable as supported by the lack of caspase-3 and -8 activation, the latter resulting in only faint activation after exposure to higher CoCl2 doses for prolonged time points. Furthermore, CoCl2 treatment resulted in atrophy of the C2C12 myotubes which was characterized by the increased expression of HSP25 and GRP94 stress proteins and other typical `pro-atrophic molecular hallmarks, such as early activation of the NF-kB pathway and down-regulation of AKT phosphorylation, followed by the activation of the proteasome and autophagy systems. Overall, these results suggested that cobalt may impact skeletal muscle homeostasis as an inducer of cell necrosis and myofiber atrophy.
authors.affiliation: Unit of Biotechnologies, Department of Molecular and Translational Medicine, University of Brescia, Brescia I-25123, Italy; Interuniversity Institute of Myology IIM, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Rovetta
authors.forename: Alessandra
authors.initials: A
authors.lastname: Stacchiotti
authors.forename: Fiorella
authors.initials: F
authors.lastname: Faggi
authors.forename: Simona
authors.initials: S
authors.lastname: Catalani
authors.forename: Pietro
authors.initials: P
authors.lastname: Apostoli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fanzani
authors.forename: Maria Francesca
authors.initials: MF
authors.lastname: Aleo
mesh_terms: D001284:Atrophy; D001343:Autophagy; D015153:Blotting, Western; D016923:Cell Death / Q000187:drug effects*; D002460:Cell Line; D003035:Cobalt / Q000633:toxicity*; D004396:Coloring Agents; D005470:Fluorometry; D007150:Immunohistochemistry; D007202:Indicators and Reagents; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000473:pathology*; D032446:Myoblasts / Q000187:drug effects; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D019736:Prostheses and Implants / Q000009:adverse effects; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D004396:Coloring Agents; D007202:Indicators and Reagents; D016328:NF-kappa B; D013778:Tetrazolium Salts; D013844:Thiazoles; D003035:Cobalt; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; D046988:Proteasome Endopeptidase Complex; C022616:thiazolyl blue; C018021:cobaltous chloride
keywords: Atrophy; C2C12 myotubes; Cell stress; Cobalt; Necroptosis; Skeletal muscle