title: Plasma membrane contributes to the formation of pre-autophagosomal structures.
abstract: Autophagy is a catabolic process in which lysosomes degrade intracytoplasmic contents transported in double-membraned autophagosomes. Autophagosomes are formed by the elongation and fusion of phagophores, which derive from pre-autophagosomal structures. The membrane origins of autophagosomes are unclear and may involve multiple sources, including the endoplasmic reticulum and mitochondria. Here we show in mammalian cells that the heavy chain of clathrin interacts with Atg16L1 and is involved in the formation of Atg16L1-positive early autophagosome precursors. Atg16L1 associated with clathrin-coated structures, and inhibition of clathrin-mediated internalization decreased the formation of both Atg16L1-positive precursors and mature autophagosomes. We tested and demonstrated that the plasma membrane contributes directly to the formation of early Atg16L1-positive autophagosome precursors. This may be particularly important during periods of increased autophagosome formation, because the plasma membrane may serve as a large membrane reservoir that allows cells periods of autophagosome synthesis at levels many-fold higher than under basal conditions, without compromising other processes.
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2XY, UK.
authors.forename: Brinda
authors.initials: B
authors.lastname: Ravikumar
authors.forename: Kevin
authors.initials: K
authors.lastname: Moreau
authors.forename: Luca
authors.initials: L
authors.lastname: Jahreiss
authors.forename: Claudia
authors.initials: C
authors.lastname: Puri
authors.forename: David C
authors.initials: DC
authors.lastname: Rubinsztein
mesh_terms: D001343:Autophagy / Q000502:physiology*; D000071183:Autophagy-Related Proteins; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D010588:Phagosomes / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D017384:Sequence Deletion / Q000235:genetics
chemical_list: C518959:ATG16L1 protein, human; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D002966:Clathrin