title: Direct interaction of Plin2 with lipids on the surface of lipid droplets: a live cell FRET analysis.
abstract: Despite increasing awareness of the health risks associated with excess lipid storage in cells and tissues, knowledge of events governing lipid exchange at the surface of lipid droplets remains unclear. To address this issue, fluorescence resonance energy transfer (FRET) was performed to examine live cell interactions of Plin2 with lipids involved in maintaining lipid droplet structure and function. FRET efficiencies (E) between CFP-labeled Plin2 and fluorescently labeled phosphatidylcholine, sphingomyelin, stearic acid, and cholesterol were quantitated on a pixel-by-pixel basis to generate FRET image maps that specified areas with high E (>60%) in lipid droplets. The mean E and the distance R between the probes indicated a high yield of energy transfer and demonstrated molecular distances on the order of 44-57 Å, in keeping with direct molecular contact. In contrast, FRET between CFP-Plin2 and Nile red was not detected, indicating that the CFP-Plin2/Nile red interaction was beyond FRET proximity (>100 Å). An examination of the effect of Plin2 on cellular metabolism revealed that triacylglycerol, fatty acid, and cholesteryl ester content increased while diacylglycerol remained constant in CFP-Plin2-overexpressing cells. Total phospholipids also increased, reflecting increased phosphatidylcholine and sphingomyelin. Consistent with these results, expression levels of enzymes involved in triacylglycerol, cholesteryl ester, and phospholipid synthesis were significantly upregulated in CFP-Plin2-expressing cells while those associated with lipolysis either decreased or were unaffected. Taken together, these data show for the first time that Plin2 interacts directly with lipids on the surface of lipid droplets and influences levels of key enzymes and lipids involved in maintaining lipid droplet structure and function.
authors: Dept. of Biochemistry and Molecular Biology, Michigan State Univ., East Lansing, MI 48824, USA.
authors: Avery L
authors: AL
authors: McIntosh
authors: Subramanian
authors: S
authors: Senthivinayagam
authors: Kenneth C
authors: KC
authors: Moon
authors: Shipra
authors: S
authors: Gupta
authors: Joel S
authors: JS
authors: Lwande
authors: Cameron C
authors: CC
authors: Murphy
authors: Stephen M
authors: SM
authors: Storey
authors: Barbara P
authors: BP
authors: Atshaves
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D000070780:Perilipin-2; D011485:Protein Binding / Q000502:physiology; D013329:Structure-Activity Relationship; D013499:Surface Properties
chemical_list: D008565:Membrane Proteins; C000602982:PLIN2 protein, human; D000070780:Perilipin-2; C000602983:Plin2 protein, mouse