Abstract
The article summarizes our actual knowledge of muscle atrophy, its signalling and execution. Among the main triggers that inhibit growth or activate degradation of the muscle there are inflammatory cytokines, hypoxia, inactivity, depletion of energetic substrates and oxidation stress, the humoral triggers are myostatin, insulin, glucocorticoids, catecholamines and thyroidal hormones.
Their intracelullar signalling converges on two main transcription factors, NF-κB and FoxO. Their activation leads to an expression of atrogenes.
Products of these genes are enzymes of proteolytic complexes themselves. Ubiquitin-proteasom system represents the central role in the regulation of interaction beteween other proteolytic systems.
Myofibrilar proteins are decomposed to elementar amino acids, which are then released to circulation. In that form they can be used as an alternative energy source or as acute-phase proten precursors.