title: Transiently expressed ATG16L1 inhibits autophagosome biogenesis and aberrantly targets RAB11-positive recycling endosomes.
abstract: The membrane source for autophagosome biogenesis is an unsolved mystery in the study of autophagy. ATG16L1 forms a complex with ATG12-ATG5 (the ATG16L1 complex). The ATG16L1 complex is recruited to autophagic membranes to convert MAP1LC3B-I to MAP1LC3B-II. The ATG16L1 complex dissociates from the phagophore before autophagosome membrane closure. Thus, ATG16L1 can be used as an early event marker for the study of autophagosome biogenesis. We found that among 3 proteins in the ATG16L1 complex, only ATG16L1 formed puncta-like structures when transiently overexpressed. ATG16L1+puncta formed by transient expression could represent autophagic membrane structures. We thoroughly characterized the transiently expressed ATG16L1 in several mammalian cell lines. We found that transient expression of ATG16L1 not only inhibited autophagosome biogenesis, but also aberrantly targeted RAB11-positive recycling endosomes, resulting in recycling endosome aggregates. We conclude that transient expression of ATG16L1 is not a physiological model for the study of autophagy. Caution is warranted when reviewing findings derived from a transient expression model of ATG16L1.
authors.affiliation: a Department of Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.
authors.forename: Jiehua
authors.initials: J
authors.lastname: Li
authors.affiliation: a Department of Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.
authors.forename: Zhixia
authors.initials: Z
authors.lastname: Chen
authors.affiliation: a Department of Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Stang
authors.affiliation: a Department of Surgery , University of Pittsburgh School of Medicine , Pittsburgh , PA , USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Gao
mesh_terms: D000072283:A549 Cells; D000818:Animals; D000071182:Autophagosomes / Q000378:metabolism*; D000071183:Autophagy-Related Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D021381:Protein Transport; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D049452:Green Fluorescent Proteins; D008869:Microtubule-Associated Proteins; D019869:Phosphatidylinositol 3-Kinases; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C518959:ATG16L1 protein, human; C532820:Atg16l1 protein, mouse; C502070:MAP1LC3B protein, human
keywords: ATG12; ATG16L1; ATG5; RAB11; autophagosome biogenesis; autophagy; recycling endosome