Electron tomography reveals the endoplasmic reticulum as a membrane source for autophagosome formation.
The origin and source of autophagosomal membranes are long-standing questions. By electron microscopy, we show that the endoplasmic reticulum (ER) associates with early autophagic structures called isolation membranes (IM) or phagophores in mammalian culture cells. Overexpression of a mutant of Atg4B, which causes defects in autophagosome formation, caused accumulation of ER-IM complexes. Electron tomography revealed the ER-IM complex as a subdomain of the ER forming a cradle encircling the IM, and showed that both ER and isolation membranes are interconnected.
Hayashi-Nishino
Mitsuko
M
Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.
Fujita
Naonobu
N
Noda
Takeshi
T
Yamaguchi
Akihito
A
Yoshimori
Tamotsu
T
Yamamoto
Akitsugu
A
D000818:Animals; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D055032:Electron Microscope Tomography; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D010588:Phagosomes / Q000378:metabolism / Q000648:ultrastructure
D003546:Cysteine Endopeptidases