Abstract 

Phase-separated droplets with liquid-like properties can be degraded by autophagy, but the mechanism underlying this degradation is poorly understood. We have recently derived a physical model to investigate the interaction between autophagic membranes and such droplets, uncovering that wetting interactions underlie droplet-membrane contact. We found that the competition between droplet surface tension and the increasing tendency of growing membrane sheets to bend determines whether a droplet is completely engulfed or isolated in a piecemeal fashion, a process we term fluidophagy. Intriguingly, we found that another critical parameter of droplet-membrane interactions, the spontaneous curvature of the membrane, which can be affected by interactions with the droplet, determines whether the droplet is degraded by autophagy or – counterintuitively – serves as a platform from which autophagic membranes expand into the cytosol.