title: Lipidomics reveals that adiposomes store ether lipids and mediate phospholipid traffic.
abstract: Lipid droplets are accumulations of neutral lipids surrounded by a monolayer of phospholipids and associated proteins. Recent proteomic analysis of isolated droplets suggests that they are part of a dynamic organelle system that is involved in membrane traffic as well as packaging and distributing lipids in the cell. To gain a better insight into the function of droplets, we used a combination of mass spectrometry and NMR spectroscopy to characterize the lipid composition of this compartment. In addition to cholesteryl esters and triacylglycerols with mixed fatty acid composition, we found that approximately 10-20% of the neutral lipids were the ether lipid monoalk(en)yl diacylglycerol. Although lipid droplets contain only 1-2% phospholipids by weight, >160 molecular species were identified and quantified. Phosphatidylcholine (PC) was the most abundant class, followed by phosphatidylethanolamine (PE), phosphatidylinositol, and ether-linked phosphatidylcholine (ePC). Relative to total membrane, droplet phospholipids were enriched in lysoPE, lysoPC, and PC but deficient in sphingomyelin, phosphatidylserine, and phosphatidic acid. These results suggest that droplets play a central role in ether lipid metabolism and intracellular lipid traffic.
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA.
authors.forename: René
authors.initials: R
authors.lastname: Bartz
authors.forename: Wen-Hong
authors.initials: WH
authors.lastname: Li
authors.forename: Barney
authors.initials: B
authors.lastname: Venables
authors.forename: John K
authors.initials: JK
authors.lastname: Zehmer
authors.forename: Mary R
authors.initials: MR
authors.lastname: Roth
authors.forename: Ruth
authors.initials: R
authors.lastname: Welti
authors.forename: Richard G W
authors.initials: RG
authors.lastname: Anderson
authors.forename: Pingsheng
authors.initials: P
authors.lastname: Liu
authors.forename: Kent D
authors.initials: KD
authors.lastname: Chapman
mesh_terms: D001692:Biological Transport; D004075:Diglycerides / Q000032:analysis; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015388:Organelles / Q000737:chemistry*; D010743:Phospholipids / Q000032:analysis; D014280:Triglycerides / Q000032:analysis
chemical_list: D004075:Diglycerides; D008055:Lipids; D010743:Phospholipids; D014280:Triglycerides