Triglyceride-rich lipoprotein lipolysis increases aggregation of endothelial cell membrane microdomains and produces reactive oxygen species.
Triglyceride-rich lipoprotein (TGRL) lipolysis may provide a proinflammatory stimulus to endothelium. Detergent-resistant plasma membrane microdomains (lipid rafts) have a number of functions in endothelial cell inflammation. The mechanisms of TGRL lipolysis-induced endothelial cell injury were investigated by examining endothelial cell lipid rafts and production of reactive oxygen species (ROS). Lipid raft microdomains in human aortic endothelial cells were visualized by confocal microscopy with fluorescein isothiocyanate-labeled cholera toxin B as a lipid raft marker. Incubation of Atto565-labeled TGRL with lipid raft-labeled endothelial cells showed that TGRL colocalized with the lipid rafts, TGRL lipolysis caused clustering and aggregation of lipid rafts, and colocalization of TGRL remnant particles on the endothelial cells aggregated lipid rafts. Furthermore, TGRL lipolysis caused translocation of low-density lipoprotein receptor-related protein, endothelial nitric oxide synthase, and caveolin-1 from raft regions to nonraft regions of the membrane 3 h after treatment with TGRL lipolysis. TGRL lipolysis significantly increased the production of ROS in endothelial cells, and both NADPH oxidase and cytochrome P-450 inhibitors reduced production of ROS. Our studies suggest that alteration of lipid raft morphology and composition and ROS production could contribute to TGRL lipolysis-mediated endothelial cell injury.
Wang
Limin
L
Dept. of Internal Medicine, Univ. of California, Davis, CA 95616, USA. lwang@ucdavis.edu
Sapuri-Butti
Annapoorna R
AR
Aung
Hnin Hnin
HH
Parikh
Atul N
AN
Rutledge
John C
JC
D051242:Caveolin 1 / Q000378:metabolism; D002478:Cells, Cultured; D002772:Cholera Toxin; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006801:Humans; D015228:Hypertriglyceridemia / Q000378:metabolism; D008066:Lipolysis; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism* / Q000473:pathology; D018613:Microscopy, Confocal; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D021381:Protein Transport; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism*
C495540:CAV1 protein, human; D051242:Caveolin 1; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D008074:Lipoproteins; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D017382:Reactive Oxygen Species; D014280:Triglycerides; D002772:Cholera Toxin; D003577:Cytochrome P-450 Enzyme System; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; D008071:Lipoprotein Lipase; D016650:Fluorescein-5-isothiocyanate