title: Autophagy-independent function of Atg8 in lipid droplet dynamics in yeast.
abstract: Dynamic features of lipid droplets include growth and degradation of the organelle. Autophagy, a system for the transport of cytoplasmic components to be degraded into the lysosome/vacuole, is regarded to be responsible for the degradation of lipid droplets. Atg8 protein in the yeast Saccharomyces cerevisiae is recruited to membrane structures synthesized during autophagy via a lipidation process. In this study, we report a novel function of Atg8 in lipid droplet dynamics. We found that loss of Atg8 specifically resulted in a decrease in the quantity of lipid droplets in cells at stationary phase. This protein was detected in a lipid droplet fraction independent of its lipidation. Loss of Atg8 hemifusion activity also caused a decrease in the quantity of lipid droplets. Consistent with these results, isolated lipid droplets underwent assembly into large clusters when incubated with Atg8 possessing hemifusion activity. The loss of Atg8 did not reduce the quantity of lipid droplets in a mutant defective in lipolysis, another system for lipid droplet degradation, which strongly suggests the function of Atg8 in antagonizing lipolysis. Together these results indicate a specific function of Atg8 in maintaining the quantity of lipid droplets that is independent of its autophagic function.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Maeda
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture.
authors.forename: Masahide
authors.initials: M
authors.lastname: Oku
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture.|Research Unit for Physiological Chemistry, the Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kitashirakawa-Oiwake, Kyoto, Sakyo 606-8502, Japan.
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Sakai
mesh_terms: D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family / Q000235:genetics / Q000378:metabolism*; D015151:Immunoblotting; D008049:Lipase / Q000235:genetics / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism*; D008066:Lipolysis; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D000097573:Red Fluorescent Protein
chemical_list: D000071190:Autophagy-Related Protein 8 Family; D008049:Lipase; D008164:Luminescent Proteins; D029701:Saccharomyces cerevisiae Proteins; D000097573:Red Fluorescent Protein; C113757:ATG8 protein, S cerevisiae; C476342:TGL3 protein, S cerevisiae; C506904:Tgl4 protein, S cerevisiae
keywords: autophagy; lipid; lipid droplet; lipolysis; lysosome; yeast