The fate of autophagosomal membrane components.

During macroautophagy/autophagy, autophagosomes fuse with lysosomes to form autolysosomes. After fusion, the autophagosome inner membrane and enclosed substrates are degraded and transported out of lysosomes for recycling. The lysosomal membrane components are recycled by autophagic lysosome reformation (ALR) to generate new lysosomes. However, the fate of autophagosome outer membrane components on autolysosomes remains unknown. Our recent work discovered that autophagosome outer membrane components are not degraded but are recycled through an unidentified process which we named autophagosomal components recycling (ACR). Further investigation revealed the recycler complex (SNX4-SNX5-SNX17) responsible for ACR. The discovery of ACR not only fills a missing part in autophagy, but also reveals a new recycling pathway on autolysosomes.