aging of cultured human myotubes. Homo sapiens

Aging of skeletal muscle tissue is characterized by loss of metabolic and contractile competence. It is thought that this phenomenon is driven via extrinsic and intrinsic factors. In order to identify age-dependent changes intrinsic to the muscle cell, microarray transcriptional profiles and measurements of glucose metabolism were performed in primary cultured human myotubes at different time points over seven weeks. Aging in culture tended to reduce myotube glucose metabolism, oxidative and storage capacities, despite elevation of glucose transport. The mitochondrial membrane potential slightly increased, whereas peroxidation of cell membrane lipids declined and membrane integrity was preserved. Transcriptional analysis revealed a fall in genes involved in glucose metabolism and oxidative phosphorylation, while stress defense genes were elevated. Expression of numerous genes coding for muscle contractile proteins and calcium-regulating proteins, was gradually decreased during aging of cultured myotubes. Transcripts of genes involved in cell growth, matrix and motility markedly rose while those involved in cell adhesion dropped. In conclusion, aging myotubes in culture exhibit a loss of glucose metabolic capacity. They are characterized by a shift from a contractile to a growth-survival, matrix-remodeling phenotype. This pattern of changes, linked to intrinsic factors, displays significant similarities with aging of muscle from primates and human subjects. Keywords = aging Keywords = muscle cell biopsy Keywords = myotubes Keywords = glucose Keywords: time-course