title: Uba1 functions in Atg7- and Atg3-independent autophagy.
abstract: Autophagy is a conserved process that delivers components of the cytoplasm to lysosomes for degradation. The E1 and E2 enzymes encoded by Atg7 and Atg3 are thought to be essential for autophagy involving the ubiquitin-like protein Atg8. Here, we describe an Atg7- and Atg3-independent autophagy pathway that facilitates programmed reduction of cell size during intestine cell death. Although multiple components of the core autophagy pathways, including Atg8, are required for autophagy and cells to shrink in the midgut of the intestine, loss of either Atg7 or Atg3 function does not influence these cellular processes. Rather, Uba1, the E1 enzyme used in ubiquitylation, is required for autophagy and reduction of cell size. Our data reveal that distinct autophagy programs are used by different cells within an animal, and disclose an unappreciated role for ubiquitin activation in autophagy.
authors.affiliation: Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
authors.forename: Tsun-Kai
authors.initials: TK
authors.lastname: Chang
authors.forename: Bhupendra V
authors.initials: BV
authors.lastname: Shravage
authors.forename: Sebastian D
authors.initials: SD
authors.lastname: Hayes
authors.forename: Christine M
authors.initials: CM
authors.lastname: Powers
authors.forename: Rachel T
authors.initials: RT
authors.lastname: Simin
authors.forename: J
authors.initials: J
authors.lastname: Wade Harper
authors.forename: Eric H
authors.initials: EH
authors.lastname: Baehrecke
mesh_terms: D000818:Animals; D001343:Autophagy; D000071193:Autophagy-Related Protein 7; D048429:Cell Size; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology*; D005786:Gene Expression Regulation; D007422:Intestines / Q000166:cytology / Q000201:enzymology*; D007814:Larva / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D009928:Organ Specificity; D020033:Protein Isoforms / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000235:genetics / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000172:deficiency / Q000235:genetics*; D054875:Ubiquitination
chemical_list: C530193:Atg7 protein, Drosophila; C527373:Atg8a protein, Drosophila; D029721:Drosophila Proteins; D020033:Protein Isoforms; D025801:Ubiquitin; D044763:Ubiquitin-Conjugating Enzymes; D000071193:Autophagy-Related Protein 7; C542423:Uba1 protein, Drosophila; D044764:Ubiquitin-Activating Enzymes