Autophagosome biogenesis requires efficient mobilization and delivery of membranes from intracellular sources. How these membranes are mobilized remains poorly understood. Our recent work reported an autophagic signal-induced membrane mobilization event from the ER-Golgi intermediate compartment (ERGIC) to generate an early autophagosomal membrane precursor. We found that starvation activates the autophagic phosphatidylinositol 3-kinase, which promotes a relocation of COPII proteins from the ER-exit sites to the ERGIC. The relocation of COPII generates ERGIC-derived COPII vesicles as a membrane template for LC3 lipidation, a key step for autophagosome biogenesis.
Keywords: COPII; ER-Golgi intermediate compartment; LC3; autophagosome; autophagy; phosphatidylinositol 3-kinase.