Skeletal muscle autophagy: a new metabolic regulator

• The skeletal muscle autophagy signaling pathways contain many new, novel regulators.
• The benefits of exercise involve regulating skeletal muscle autophagy.
• Skeletal muscle autophagy requires a very fine balance for healthy muscle.
• Stored nutrients can be trafficked by autophagy and broken down in the lysosome.

Autophagy classically functions as a physiological process to degrade cytoplasmic components, protein aggregates, and/or organelles, as a mechanism for nutrient breakdown, and as a regulator of cellular architecture. Proper autophagic flux is vital for both functional skeletal muscle, which controls the support and movement of the skeleton, and muscle metabolism. The role of autophagy as a metabolic regulator in muscle has been previously studied; however, the underlying molecular mechanisms that control autophagy in skeletal muscle have only recently begun to emerge. We review recent literature on the molecular pathways controlling skeletal muscle autophagy and discuss how they connect autophagy to metabolic regulation. We also focus on the implications these studies hold for understanding metabolic and muscle-wasting diseases.