Abstract
Skeletal muscle is a highly plastic tissue, able to change its mass and
functional properties in response to several stimuli. Skeletal muscle mass is
influenced by the balance between protein synthesis and breakdown, which is
regulated by several signaling pathways. The relative contribution of
Akt/mTOR signaling, ubiquitin-proteasome pathway, autophagy among other
signaling pathways to protein turnover and, therefore, to skeletal muscle mass,
differs depending on the wasting or loading condition and muscle type. By
modulating mitochondria biogenesis, PGC-1α has a major role in the
cell’s bioenergetic status and, thus, on protein turnover. In fact,
rates of protein turnover regulate differently the levels of distinct protein
classes in response to atrophic or hypertrophic stimuli. Mitochondrial protein
turnover rates may be enhanced in wasting conditions, whereas the increased
turnover of myofibrillar proteins triggers muscle mass gain. The present review
aims to update the knowledge on the molecular pathways implicated in the
regulation of protein turnover in skeletal muscle, focusing on how distinct
muscle proteins may be modulated by lifestyle interventions with emphasis on
exercise training. The comprehensive analysis of the anabolic effects of
exercise programs will pave the way to the tailored management of muscle wasting
conditions.
Key words
protein synthesis - proteolysis - mitochondrial homeostasis - signaling - exercise training