Winter bear serum promotes muscle cell growth, increases protein content, and triggers metabolic switch and hibernation-like signatures in human myotubes

still unknown bear circulating factors have been reported to induce a 40% decrease of the net proteolytic rate in isolated rat muscles, accompanied by downregulation of expression levels of both lysosomal and ubiquitin-dependent proteolytic factors. Here we investigated the phenotype of cultivated human myocytes treated with hibernating bear serum, by disentangling impacts at the trophic, protein balance, and transcriptome and proteome levels. This study represents the first step towards characterization of the winter bear serum potential as a source of new therapeutic molecules to fight against human muscle atrophy. In vitro culture of fully differentiated human myotubes were treated during 48 hours with either winter or summer bear serum at a final concentration of 5%. After 48hours, cells were harvested for further analysis.