title: Oxidized LDL induces mitochondrially associated reactive oxygen/nitrogen species formation in endothelial cells.
abstract: Exposure of cells to complex mixtures of oxidized lipids such as those found in oxidized low-density lipoprotein (oxLDL) induce reactive oxygen and nitrogen species (ROS/RNS) formation. The source of the ROS/RNS within cells is unknown; it is thought they may be involved in redox cell signaling. Although this possibility was initially overlooked, it is becoming clear that mitochondria, which are a source of superoxide and hydrogen peroxide, may play a critical role in the response of cells on exposure to oxidized lipids. In this study, we tested the possibility that mitochondria are a potential source of oxLDL-dependent formation of ROS/RNS in endothelial cells. Using confocal microscopy, we demonstrated that a significant proportion of oxLDL-dependent dichlorodihydrofluorescein (DCF) fluorescence is colocalized to mitochondria. In support of this concept, rho0 endothelial cells showed a substantial decrease in ROS/RNS formation stimulated by oxLDL. In contrast, mostly nonmitochondrial DCF fluorescence was detected in cells exposed to an extracellular source of hydrogen peroxide. The exposure of cells to a nitric oxide synthase inhibitor and urate resulted in a decrease in oxLDL-induced DCF fluorescence that was restored by addition of nitric oxide donors to the medium. Taken together, these results suggest that oxLDL-dependent DCF fluorescence is mitochondrially associated and may be due to the formation of peroxynitrite.
authors.affiliation: Center for Free Radical Biology, Univ. of Alabama at Birmingham, Biomedical Research Bldg. II, 901 19th St. South, Birmingham, AL 35294, USA.
authors.forename: Jaroslaw W
authors.initials: JW
authors.lastname: Zmijewski
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Moellering
authors.forename: Claire
authors.initials: C
authors.lastname: Le Goffe
authors.forename: Aimee
authors.initials: A
authors.lastname: Landar
authors.forename: Anup
authors.initials: A
authors.lastname: Ramachandran
authors.forename: Victor M
authors.initials: VM
authors.lastname: Darley-Usmar
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D002074:Butanones / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D045222:Electron Transport Chain Complex Proteins / Q000037:antagonists & inhibitors; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004950:Esterases / Q000037:antagonists & inhibitors; D005452:Fluoresceins; D006801:Humans; D007093:Imidazoles; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011719:Pyrazines; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D013804:Thenoyltrifluoroacetone; D013876:Thiophenes / Q000494:pharmacology
chemical_list: D002074:Butanones; D045222:Electron Transport Chain Complex Proteins; D004791:Enzyme Inhibitors; D005452:Fluoresceins; D007093:Imidazoles; D008077:Lipoproteins, LDL; D011719:Pyrazines; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D013876:Thiophenes; C099252:oxidized low density lipoprotein; D012402:Rotenone; C029569:diacetyldichlorofluorescein; D013804:Thenoyltrifluoroacetone; C017144:coelenterazine; D019001:Nitric Oxide Synthase; D004950:Esterases