C2C12 stretch cessation models muscle atrophy and anaplerotic changes in metabolism

ABSTRACT: Studies of skeletal muscle disuse either in patients on bed rest or experimentally in animals(immobilization) have demonstrated that decreased protein synthesis is common, with transient parallel increases in protein degradation. Muscle disuse atrophy involves a process of transition from slow to fast myosin fiber types 6 . A shift toward glycolysis, decreased capacity for fat oxidation, and substrate accumulation in atrophied muscles have been reported as has accommodation of the liver with an increased gluconeogenic capacity. Recent studies have modeled skeletal muscle disuse by using cyclic stretch of differentiated myotubes (C2C12), which mimics the loading pattern of mature skeletal muscle, followed by cessation of stretch.We utilized this model to determine the metabolic changes using non-targeted metabolomics analysis of the media. We identified increases in amino acids resulting from protein degradation (largely sarcomere) that occurs with muscle atrophy that are involved in feeding the Kreb’s cycle through anaplerosis. Specifically, we identified increased alanine/proline metabolism (significantly elevated proline, alanine, glutamine, and asparagine) and increased -ketoglutaric acid, the proposed Kreb’s cycle intermediate being fed by the alanine/proline metabolic anaplerotic mechanism. Additionally, several unique pathways not clearly delineated in previous studies of muscle unloading were seen, including: 1) elevated ethanolamine and elevated keto-acids (e.g. 2-ketoleucine and 2-keovaline) represent intermediates in the Ehlrich amino acid degradation pathway, which feeds into a metabolic pathway supplying acetyl-CoA and 2-hydroxybutyrate (also significantly increased); and 2) elevated guanine, an intermediate of purine metabolism, was seen at 12 hours unloading. Given the interest in targeting different aspects of the ubiquitin proteasome system to inhibit protein degradation, this C2C12 system may allow the identification of direct and indirect alterations in metabolism due to anaplerosis or through other yet to be identified mechanisms using a non-targeted metabolomics approach.

ORGANISM(S): Mouse Mus Musculus

TISSUE(S): Muscle

SUBMITTER: Amro;Monte Ilaiwy;WIllis  

PROVIDER: ST000431 | MetabolomicsWorkbench | Sat May 28 00:00:00 BST 2016

REPOSITORIES: MetabolomicsWorkbench