Endothelial NADPH oxidase: mechanism of activation by low-density lipoprotein.
Exposure to atherogenic levels of low-density lipoprotein (LDL) causes elevated reactive oxygen species (ROS) production by human endothelial cells (ECs). NADPH oxidase is thought to be the main source of ROS generated by LDL-activated ECs. The mechanism by which this lipoprotein activates endothelial NADPH oxidase is incompletely understood. To gain further insight into the signaling pathway, the authors have examined the effects of inhibitors to various signal transducing enzymes, including the G(i)-protein coupled receptor (pertussis toxin), Src tyrosine kinase (PP1), phospholipase C-gamma (U73122), phosphatidylinositol 3-kinase (LY294002), p42/p44 mitogen-activated protein kinase (MAPK) kinase (PD98059), p38 MAPK (SB203580), protein kinase C (Ro 318220, GF 109203X, Go 6976), and cytosolic phospholipase A(2) (AACOCF3), on the ROS-producing capacity ECs activated by LDL. Exposure of cultured ECs to LDL (0.45 mg protein/mL) stimulated ROS formation, as measured using a 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate assay. This effect was partially inhibited by Ro 318220, GF 109203X, U73122, and SB203580, and blocked or nearly completely inhibited by PP1, pertussis toxin, LY294002, PD98059, and AACOCF3. Only a partial, minor inhibition occurred with the protein kinase C inhibitor, Go 6976. These results are most consistent with LDL activating endothelial NADPH oxidase, predominantly through a signaling pathway that leads to cytosolic phospholipase A(2) activation.
O'Donnell
Robert W
RW
Department of Biology, State University of New York College at Geneseo, Geneseo, New York, USA.
Johnson
David K
DK
Ziegler
Linda M
LM
DiMattina
Andrew J
AJ
Stone
Robert I
RI
Holland
James A
JA
D001095:Arachidonic Acids / Q000494:pharmacology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000201:enzymology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019255:NADPH Oxidases / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma; D010741:Phospholipases A / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D048051:p38 Mitogen-Activated Protein Kinases; D019061:src-Family Kinases / Q000378:metabolism
D001095:Arachidonic Acids; D002867:Chromones; D004791:Enzyme Inhibitors; D004963:Estrenes; D005419:Flavonoids; D007093:Imidazoles; D007211:Indoles; D008077:Lipoproteins, LDL; D008301:Maleimides; D009025:Morpholines; D011725:Pyridines; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; C081565:arachidonyltrifluoromethane; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019255:NADPH Oxidases; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010741:Phospholipases A; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; C070515:bisindolylmaleimide I; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C064758:Ro 31-8220