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Autophagic Punctum

Electron tomography reveals the endoplasmic reticulum as a membrane source for autophagosome formation

Mitsuko Hayashi-Nishino, Naonobu Fujita, Takeshi Noda, Akihito Yamaguchi, Tamotsu Yoshimori and Akitsugu Yamamoto

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.

Punctum to: Hayashi-Nishino M, Fujita N, Noda T, Yamaguchi A, Yoshimori T, Yamamoto A. A subdomain of the endoplasmic reticulum forms a cradle for autophagosome formation. Nat Cell Biol 2009;11:1433-7; PMID: 19898463; DOI: 10.1038/ncb1991.

Authors

Mitsuko Hayashi-Nishino

Department of Cell Membrane Biology; Institute of Scientific and Industrial Research; Osaka University; Ibaraki, Osaka Japan; Faculty of Bioscience; Nagahama Institute of Bio-Science and Technology; Nagahama, Shiga Japan

Naonobu Fujita

Department of Cellular Regulation; Research Institute for Microbial Diseases; Osaka University; Suita, Osaka Japan

Takeshi Noda

Department of Cellular Regulation; Research Institute for Microbial Diseases; Osaka University; Suita, Osaka Japan

Akihito Yamaguchi

Department of Cell Membrane Biology; Institute of Scientific and Industrial Research; Osaka University; Ibaraki, Osaka Japan

Tamotsu Yoshimori

Department of Cellular Regulation; Research Institute for Microbial Diseases; Osaka University; Suita, Osaka Japan

Akitsugu Yamamoto Corresponding author: a_yamamoto@nagahama-i-bio.ac.jp

Nagahama Institute of Bioscience and Technology