The role of lysosomes in autophagy

Autophagy is a self-digestive mechanism essential for removing damaged organelles or misfolded proteins by delivering them to the lysosome for degradation and recycling. This quality-control system constitutes a key outcome driven by environmental stresses such as nutrient or growth factor insufficiency, energy depletion, or hypoxia. The integration and cross talk between these various input signals takes place at the lysosomal surface. Therefore, besides providing the means for degradation, lysosomes represent a central organelle regulating autophagy and cellular adaptation. This adaptive process is controlled by the molecular machinery attached to the lysosomal surface and is generally governed by the mechanistic/mammalian target of rapamycin complex 1 (mTORC1), the master kinase complex growth regulator, and its associated proteins. Herein, we summarise the current understanding of the connection between the nutrient-sensing machinery of the lysosome and the regulation of autophagic activity.