title: The two C. elegans ATG-16 homologs have partially redundant functions in the basal autophagy pathway.
abstract: The presence of multiple homologs of the same yeast ATG genes endows an extra layer of complexity on the autophagic machinery in higher eukaryotes. The physiological function of individual homologs in the autophagy pathway remains poorly understood. Here we characterized the function of the two atg16 homologs, atg-16.1 and atg-16.2, in the autophagy pathway in C. elegans. We showed that atg-16.2 mutants exhibit a stronger autophagic defect than atg-16.1 mutants. atg-16.2; atg-16.1 double mutants display a much more severe defect than either single mutant. ATG-16.1 and ATG-16.2 interact with themselves and each other and also directly associate with ATG-5. atg-16.1 mutant embryos exhibit a wild-type expression and distribution pattern of LGG-1/Atg8, while LGG-1 puncta are markedly fewer in number and weaker in intensity in atg-16.2 mutants. In atg-16.2; atg-16.1 double mutants, the lipidated form of LGG-1 accumulates, but LGG-1 puncta are completely absent. ATG-16.2 ectopically expressed on the plasma membrane provides novel sites of LGG-1 puncta formation. We also demonstrated that the C-terminal WD repeats are dispensable for the role of atg-16.2 in aggrephagy (the degradation of protein aggregates by autophagy). Genetic epistasis analysis placed atg-16.2 upstream of atg-2, epg-6, and atg-18. Our study indicated that C. elegans ATG-16s are involved in specifying LGG-1 puncta formation and the two ATG-16 homologs have partially redundant yet distinct functions in the aggrephagy pathway.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Fan
authors.initials: F
authors.lastname: Wu
authors.forename: Xingwei
authors.initials: X
authors.lastname: Wang
authors.forename: Hongwei
authors.initials: H
authors.lastname: Du
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001343:Autophagy / Q000235:genetics*; D000071183:Autophagy-Related Proteins; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian; D018507:Gene Expression Regulation, Developmental; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology; D017385:Sequence Homology; D015398:Signal Transduction / Q000235:genetics
chemical_list: C498649:ATG16 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; C587195:LGG-1 protein, C elegans; D008869:Microtubule-Associated Proteins; D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; C000591232:atg-16.1 protein, C elegans; C000591233:atg-16.2 protein, C elegans