Molecular and Cellular Determinants of Skeletal Muscle Atrophy and Hypertrophy

Vittorio Sartorelli^* and Marcella Fulco

Muscle Gene Expression Group Laboratory of Muscle Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Gloss: This STKE Review with two figures and 133 references discusses the signaling pathways that are implicated in both building muscle and losing muscle. Protein degradation pathways are activated in response to lack of muscle use, which leads to muscle atrophy. Muscle hypertrophy in response to exercise involves both changes in gene expression and protein activities in the existing myofibers and recruitment of satellite cells to increase myofiber numbers. Studies aimed at understanding the mechanisms underlying either muscular atrophy or hypertrophy have begun to identify the physiological determinants and clarify the molecular pathways responsible for the maintenance of muscle mass.

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*Corresponding author. E-mail: sartorev{at}mail.nih.gov

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