  Autophagy is an intracellular degradation process that is mediated by de novo
formation of autophagosomes. Autophagosome formation involves dynamic
morphological changes; a disk-shaped membrane cisterna grows, bends to become a
cup-shaped structure, and finally develops into a spherical autophagosome. We
have constructed a theoretical model that integrates the membrane morphological
change and entropic partitioning of putative curvature generators, which we
have used to investigate the autophagosome formation process quantitatively. We
show that the membrane curvature and the distribution of the curvature
generators stabilize disk- and cup-shaped intermediate structures during
autophagosome formation, which is quantitatively consistent with in vivo
observations. These results suggest that various autophagy proteins with
membrane curvature-sensing properties control morphological change by
stabilizing these intermediate structures. Our model provides a framework for
understanding autophagosome formation.
