title: Lipid Droplets Form from Distinct Regions of the Cell in the Fission Yeast Schizosaccharomyces pombe.
abstract: Eukaryotic cells store cholesterol/sterol esters (SEs) and triacylglycerols (TAGs) in lipid droplets, which form from the contiguous endoplasmic reticulum (ER) network. However, it is not known if droplets preferentially form from certain regions of the ER over others. Here, we used fission yeast Schizosaccharomyces pombe cells where the nuclear and cortical/peripheral ER domains are distinguishable by light microscopy to show that SE-enriched lipid droplets form away from the nucleus at the cell tips, whereas TAG-enriched lipid droplets form around the nucleus. Sterols localize to the regions of the cells where droplets enriched in SEs are observed. TAG droplet formation around the nucleus appears to be a strong function of diacylglycerol (DAG) homeostasis with Cpt1p, which coverts DAG into phosphatidylcholine and phosphatidylethanolamine localized exclusively to the nuclear ER. Also, Dgk1p, which converts DAG into phosphatidic acid localized strongly to the nuclear ER over the cortical/peripheral ER. We also show that TAG more readily translocates from the ER to lipid droplets than do SEs. The results augment the standard lipid droplet formation model, which has SEs and TAGs flowing into the same nascent lipid droplet regardless of its biogenesis point in the cell.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Meyers
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Zuania P
authors.initials: ZP
authors.lastname: Del Rio
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Beaver
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Morris
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Taylor M
authors.initials: TM
authors.lastname: Weiskittel
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.
authors.forename: Amany K
authors.initials: AK
authors.lastname: Alshibli
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Jaana
authors.initials: J
authors.lastname: Mannik
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Morrell-Falvey
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996-2200, USA.|Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.|Institute of Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Dalhaimer
mesh_terms: D004075:Diglycerides / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: D004075:Diglycerides; D014280:Triglycerides
keywords: endoplasmic reticulum; fission yeast; lipid body; lipid droplet; sterol ester; triacylglycerol