title: A subdomain of the endoplasmic reticulum forms a cradle for autophagosome formation.
abstract: Autophagy is a bulk degradation process in eukaryotic cells and has fundamental roles in cellular homeostasis.The origin and source of autophagosomal membranes are long-standing questions in the field. Using electron microscopy, we show that, in mammalian culture cells, the endoplasmic reticulum (ER) associates with early autophagic structures called isolation membranes (IMs). Overexpression of an Atg4B mutant, which causes defects in autophagosome formation, induces the accumulation of ER-IM complexes. Electron tomography revealed that the ER-IM complex appears as a subdomain of the ER that formed a cradle encircling the IM, and showed that both ER and isolation membranes are interconnected.
authors.affiliation: Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Hayashi-Nishino
authors.forename: Naonobu
authors.initials: N
authors.lastname: Fujita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Noda
authors.forename: Akihito
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Yoshimori
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D051379:Mice; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron; D010588:Phagosomes / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; C426003:ZFYVE1 protein, human; C507524:ATG4B protein, human; D003546:Cysteine Endopeptidases