title: Caveolins sequester FA on the cytoplasmic leaflet of the plasma membrane, augment triglyceride formation, and protect cells from lipotoxicity.
abstract: Ectopic expression of caveolin-1 in HEK293 cells enhances FA sequestration in membranes as measured by a pH-sensitive fluorescent dye (1). We hypothesized that sequestration of FA is due to the enrichment of caveolin in the cytosolic leaflet and its ability to facilitate the formation of lipid rafts to buffer high FA levels. Here we show that ec-topic expression of caveolin-3 also results in enhanced FA sequestration. To further discriminate the effect that caveolins have on transmembrane FA movement and distribution, we labeled the outer membrane leaflet with fluorescein-phosphatidylethanolamine (FPE), whose emission is quenched by the presence of FA anions. Real-time measurements made with FPE and control experiments with positively charged fatty amines support our hypothesis that caveolins promote localization of FA anions through interactions with basic amino acid residues (lysines and arginines) present at the C termini of caveolins-1 and -3.
authors.affiliation: Department of Biophysics and Physiology, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Simard
authors.forename: Tova
authors.initials: T
authors.lastname: Meshulam
authors.forename: Biju K
authors.initials: BK
authors.lastname: Pillai
authors.forename: Michael T
authors.initials: MT
authors.lastname: Kirber
authors.forename: Kellen
authors.initials: K
authors.lastname: Brunaldi
authors.forename: Su
authors.initials: S
authors.lastname: Xu
authors.forename: Paul F
authors.initials: PF
authors.lastname: Pilch
authors.forename: James A
authors.initials: JA
authors.lastname: Hamilton
mesh_terms: D000588:Amines / Q000737:chemistry / Q000378:metabolism; D051242:Caveolin 1 / Q000737:chemistry / Q000378:metabolism; D051244:Caveolin 3 / Q000737:chemistry / Q000378:metabolism; D022461:Caveolins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism* / Q000633:toxicity*; D005452:Fluoresceins / Q000378:metabolism; D005786:Gene Expression Regulation; D009068:Movement; D010714:Phosphatidylethanolamines / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D000588:Amines; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D005227:Fatty Acids; D005452:Fluoresceins; C059737:N-fluoresceinylphosphatidylethanolamine; D010714:Phosphatidylethanolamines; D014280:Triglycerides
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