RRC ID 29051
Author Otto GP, Wu MY, Kazgan N, Anderson OR, Kessin RH.
Title Macroautophagy is required for multicellular development of the social amoeba Dictyostelium discoideum.
Journal J Biol Chem
Abstract Macroautophagy is a mechanism employed by eukaryotic cells to recycle non-essential cellular components during starvation, differentiation, and development. Two conjugation reactions related to ubiquitination are essential for autophagy: Apg12p conjugation to Apg5p, and Apg8p conjugation to the lipid phosphatidylethanolamine. These reactions require the action of the E1-like enzyme, Apg7p, and the E2-like enzymes, Apg3p and Apg10p. In Dictyostelium, development is induced by starvation, conditions under which autophagy is required for survival in yeast and plants. We have identified Dictyostelium homologues of 10 budding yeast autophagy genes. We have generated mutations in apg5 and apg7 that produce defects typically associated with an abrogation of autophagy. Mutants are not grossly affected in growth, but survival during nitrogen starvation is severely reduced. Starved mutant cells show little turnover of cellular constituents by electron microscopy, whereas wild-type cells show significant cytoplasmic degradation and reduced organelle number. Bulk protein degradation during starvation-induced development is reduced in the autophagy mutants. Development is aberrant; the autophagy mutants do not aggregate in plaques on bacterial lawns, but they do proceed further in development on nitrocellulose filters, forming defective fruiting bodies. The autophagy mutations are cell autonomous, because wild-type cells in a chimaera do not rescue development of the autophagy mutants. We have complemented the mutant phenotypes by expression of the cognate gene fused to green fluorescent protein. A green fluorescent protein fusion of the autophagosome marker Apg8 mislocalizes in the two autophagy mutants. We show that the Apg5-Apg12 conjugation system is conserved in Dictyostelium.
Volume 278(20)
Pages 17636-45
Published 2003-5-16
DOI 10.1074/jbc.M212467200
PII M212467200
PMID 12626495
MeSH Amino Acid Sequence Animals Autophagy* Autophagy-Related Protein 5 Autophagy-Related Protein 8 Family Cytoplasm / metabolism Dictyostelium / genetics Dictyostelium / physiology* Dictyostelium / ultrastructure Green Fluorescent Proteins Lipid Metabolism Luminescent Proteins / metabolism Microscopy, Electron Microscopy, Fluorescence Microtubule-Associated Proteins / metabolism Molecular Sequence Data Mutation Oxidoreductases / metabolism Phenotype Proteins / metabolism RNA / metabolism Recombinant Fusion Proteins / metabolism Saccharomyces cerevisiae Proteins / metabolism Sequence Homology, Amino Acid Time Factors Ubiquitin-Protein Ligases
IF 4.238
Times Cited 171
Cellular slime molds S00447 S00449