title: Autophagy machinery mediates macroendocytic processing and entotic cell death by targeting single membranes.
abstract: Autophagy normally involves the formation of double-membrane autophagosomes that mediate bulk cytoplasmic and organelle degradation. Here we report the modification of single-membrane vacuoles in cells by autophagy proteins. LC3 (Light chain 3) a component of autophagosomes, is recruited to single-membrane entotic vacuoles, macropinosomes and phagosomes harbouring apoptotic cells, in a manner dependent on the lipidation machinery including ATG5 and ATG7, and the class III phosphatidylinositol-3-kinase VPS34. These downstream components of the autophagy machinery, but not the upstream mammalian Tor (mTor)-regulated ULK-ATG13-FIP200 complex, facilitate lysosome fusion to single membranes and the degradation of internalized cargo. For entosis, a live-cell-engulfment program, the autophagy-protein-dependent fusion of lysosomes to vacuolar membranes leads to the death of internalized cells. As pathogen-containing phagosomes can be targeted in a similar manner, the death of epithelial cells by this mechanism mimics pathogen destruction. These data demonstrate that proteins of the autophagy pathway can target single-membrane vacuoles in cells in the absence of pathogenic organisms.
authors: Cell Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.
authors: Oliver
authors: O
authors: Florey
authors: Sung Eun
authors: SE
authors: Kim
authors: Cynthia P
authors: CP
authors: Sandoval
authors: Cole M
authors: CM
authors: Haynes
authors: Michael
authors: M
authors: Overholtzer
mesh_terms: D001343:Autophagy; D000071187:Autophagy-Related Protein 5; D000071193:Autophagy-Related Protein 7; D045744:Cell Line, Tumor; D058546:Class III Phosphatidylinositol 3-Kinases / Q000378:metabolism; D004705:Endocytosis; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000473:pathology; D008247:Lysosomes / Q000378:metabolism; D008561:Membrane Fusion; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D050725:Papillomavirus E7 Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D013997:Time Factors; D014162:Transfection; D044764:Ubiquitin-Activating Enzymes / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism* / Q000473:pathology
chemical_list: C502778:ATG5 protein, human; D000071187:Autophagy-Related Protein 5; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D050725:Papillomavirus E7 Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D058546:Class III Phosphatidylinositol 3-Kinases; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes