Oxidized LDL induces mitochondrially associated reactive oxygen/nitrogen species formation in endothelial cells.
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.
Zmijewski
Jaroslaw W
JW
Center for Free Radical Biology, Univ. of Alabama at Birmingham, Biomedical Research Bldg. II, 901 19th St. South, Birmingham, AL 35294, USA.
Moellering
Douglas R
DR
Le Goffe
Claire
C
Landar
Aimee
A
Ramachandran
Anup
A
Darley-Usmar
Victor M
VM
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
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