title: Subproteomic analysis of basic proteins in aged skeletal muscle following             offgel pre-fractionation.
abstract: The progressive loss of skeletal muscle mass is a serious pathophysiological             problem in the elderly, which warrants detailed biochemical studies into the underlying             mechanism of age-related fiber degeneration. Over the last few years, mass spectrometry             (MS)-based proteomics has identified a considerable number of new biomarkers of             muscle aging in humans and animal models of sarcopenia. However, interpretation             of the proteomic findings is often complicated by technical and biological limitations.             Although gel electrophoresis-based approaches represent a highly sensitive analytical             way for the large-scale and high-throughput survey of global changes in skeletal             muscle proteins during aging, often the presence of components with an isoelectric             point in the basic range is underestimated. We, therefore, carried out a comparative             subproteomic study of young versus aged rat muscle focusing on potential changes             in muscle proteins with an alkaline isoelectric point, using a combination of             offgel electrophoresis and two-dimensional (2D) slab gel electrophoresis. Offgel             electrophoresis was successfully applied as a prefractionation step to enrich             basic protein species from crude tissue extracts representing young adult versus             senescent muscle specimens. Proteomics has demonstrated alterations in a small             cohort of basic proteins during muscle aging. The mass spectrometric identification             of altered proteins and immunoblotting revealed a decrease in the glycolytic enzyme             glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a concomitant increase in             mitochondrial creatine kinase (CK) and ubiquinol cytochrome‑c reductase. This             agrees with the idea of a glycolytic-to-oxidative shift during muscle aging, which             is indicative of an overall fast-to-slow transition process in senescent rat muscle.             Thus, alterations in the abundance of metabolic enzymes appear to play a central             role in the molecular pathogenesis of age‑dependent muscle wasting.
authors.affiliation: Laboratory of Systems Medicine and Cell Biology, Department of                     Medicine, Research Institute of McGill University Health Centre, Montreal,                     QC, Canada.
authors.forename: Joan
authors.initials: J
authors.lastname: Gannon
authors.forename: Kay
authors.initials: K
authors.lastname: Ohlendieck
mesh_terms: D000375:Aging; D000818:Animals; D052281:Creatine Kinase, Mitochondrial Form / Q000378:metabolism; D014450:Electron Transport Complex III / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D015151:Immunoblotting; D013058:Mass Spectrometry; D009124:Muscle Proteins / Q000032:analysis*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D040901:Proteomics; D051381:Rats; D017208:Rats, Wistar
chemical_list: D009124:Muscle Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D052281:Creatine Kinase, Mitochondrial Form; D014450:Electron Transport Complex III