Coordination of Autophagosome-Lysosome Fusion by Atg8 Family Members

Macroautophagy is a conserved intracellular lysosomal degradative pathway, vital for the maintenance of cellular homeostasis. It is characterized by double-membrane vesicles called autophagosomes, which sequester the cytoplasmic material destined for lysosomal turnover. In a final step, autophagosomes fuse with lysosomes to release their cargo into the acidic and hydrolytic lumen of these organelles. In recent years, numerous new insights into this fusion event have been gained. Notably, many proteins implicated in autophagosome-lysosome fusion interact with members of the Atg8 protein family. Moreover, Atg8 proteins are described to have intrinsic membrane tethering and fusogenic properties themselves. Here, we summarize the current knowledge about the members of this intriguing protein family, which highlights them as possible hubs for the coordination of the final fusion stages of autophagy.