Insights into membrane dynamics in autophagy

In autophagy, the unique double membrane‐bound autophagosomes transiently emerge in the cytoplasm, sequester portion of cytosol and organelles, and eventually fuse with lysosomes to degrade the contents. The longstanding question in the filed is where autophagosome membrane comes from. We found that one of autophagy‐related (Atg) proteins, Atg14L localizes to the endoplasmic reticulum (ER) as well as autophagosome and the cytosol and its localization to the ER is essential to autophagosome formation. Meanwhile, electron tomography revealed that a subdomain of the ER forms a cradle encircling an immature autophagosome and the membranes were interconnected. Taken together, we suggest that the ER is a platform of autophagosome biogenesis. Furthermore, we revealed that autophagosome formation involves the linkage between the ER and mitochondria, which is also suggested as the autophagosome generator by another group.In addition, through investigation of autophagy against invading Salmonella, we showed that the LC3 (Atg8) system is recruited through a mechanism that is independent of the autophagosome membrane generation machinery, providing new insights into the mechanisms and the widely accepted model for selective autophagy.