Atg14L snaps up endocytic role

Autophagy – lysosome-mediated degradation of intracellular constituents within double-membrane autophagosomes – shares several vesicle-trafficking components with the endocytic pathway. Now, Jae Jung and co-workers (p. 4740) report that the autophagy protein beclin 1-associated autophagy-related key regulator (ATG14, also known and hereafter referred to as Atg14L) is a multivalent trafficking effector that regulates the maturation of endosomes as well as the formation of autophagosomes. Atg14L interacts with beclin 1, a component of the phosphatidylinositol 3-phosphate kinase class III complex that induces autophagosome membrane nucleation. To further delineate the biological functions of Atg14L, the authors screen for Atg14L-interacting partners by using a yeast two-hybrid system. They report that Atg14L binds to the SNARE effector protein SNAPIN – SNARE complexes drive membrane fusion in the endocytic pathway – and that this interaction accelerates endosomal maturation in mammalian cells without affecting autophagic degradation of cargo. The authors also show that knockdown of ATG14 in HeLa cells delays the late stage of endocytic trafficking and that expression of wild-type Atg14L or of a beclin-1-binding mutant but not of a Snapin-binding mutant rescues this phenotype. These and other results provide new insights into the crosstalk between autophagic and endocytic vesicle trafficking in eukaryotes.