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PMID: 18768752 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

An Atg4B mutant hampers the lipidation of LC3 paralogues and causes defects in autophagosome closure.

Molecular biology of the cell ·Vol. 19 ·No. 11 ·2008-11-00 ·Pages 4651-9

Fujita N, Hayashi-Nishino M, Fukumoto H, Omori H, Yamamoto A, Noda T, Yoshimori T

Abstract

In the process of autophagy, a ubiquitin-like molecule, LC3/Atg8, is conjugated to phosphatidylethanolamine (PE) and associates with forming autophagosomes. In mammalian cells, the existence of multiple Atg8 homologues (referred to as LC3 paralogues) has hampered genetic analysis of the lipidation of LC3 paralogues. Here, we show that overexpression of an inactive mutant of Atg4B, a protease that processes pro-LC3 paralogues, inhibits autophagic degradation and lipidation of LC3 paralogues. Inhibition was caused by sequestration of free LC3 paralogues in stable complexes with the Atg4B mutant. In mutant overexpressing cells, Atg5- and ULK1-positive intermediate autophagic structures accumulated. The length of these membrane structures was comparable to that in control cells; however, a significant number were not closed. These results show that the lipidation of LC3 paralogues is involved in the completion of autophagosome formation in mammalian cells. This study also provides a powerful tool for a wide variety of studies of autophagy in the future.

MeSH Terms
Animals Autophagy Autophagy-Related Proteins Catalysis Cell Line Cell Membrane/ultrastructure Cysteine Endopeptidases/metabolism Green Fluorescent Proteins/metabolism Humans Lipid Metabolism Mice Microtubule-Associated Proteins/metabolism Mutant Proteins/metabolism Mutation/genetics Phagosomes/metabolism,ultrastructure Phosphatidylethanolamines/metabolism Recombinant Fusion Proteins/metabolism Sequence Homology, Amino Acid
Chemicals
Autophagy-Related Proteins MAP1LC3A protein, human Microtubule-Associated Proteins Mutant Proteins Phosphatidylethanolamines Recombinant Fusion Proteins Green Fluorescent Proteins phosphatidylethanolamine Atg4b protein, mouse Cysteine Endopeptidases
Authors & Affiliations
7 authors, click to expand affiliations / ORCID
Fujita Naonobu
Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
Hayashi-Nishino Mitsuko
Fukumoto Hiromi
Omori Hiroko
Yamamoto Akitsugu
Noda Takeshi
Yoshimori Tamotsu
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Article Info
Journal
Molecular biology of the cell
Abbr.
Mol Biol Cell
ISSN
1939-4586
DOI
10.1091/mbc.e08-03-0312
Published
2008-11-00
Epub
2008-00-03
Pages
4651-9
Language
English
Region
United States
NLM ID
9201390
PMCID
PMC2575160
Subset
IM
External Links
PubMed source DOI: 10.1091/mbc.e08-03-0312 PMC Full Text View journal details
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