Oxidized low-density lipoprotein downregulates endothelial basic fibroblast growth factor through a pertussis toxin-sensitive G-protein pathway: mediator role of platelet-activating factor-like phospholipids.
BACKGROUND
Oxidized LDL (oxLDL) inhibits angiogenesis in part by downregulating endothelial basic fibroblast growth factor (bFGF). To determine the mechanism of the downregulation, we investigated the signal transduction pathway involving potential phospholipid mediators.


RESULTS
Cultured bovine aortic endothelial cells were incubated with PBS (lipoprotein-free control), LDL, or copper oxLDL under serum-free conditions. At 24 hours, oxLDL (50 microg/mL) decreased bFGF mRNA (Northern blot), bFGF protein (Western blot and ELISA), and concomitant DNA synthesis, all by 40% to 50% compared with PBS. LDL had no effect. Pretreating the cells with 100 ng/mL pertussis toxin (PTX) for 18 hours before oxLDL exposure almost completely blocked the inhibitory effects of oxLDL. In contrast, inhibiting other major cellular signal transduction pathways with PD-98059 (mitogen-activated protein kinase kinase inhibitor), HA-1004 (inhibitor of cGMP- and cAMP-dependent protein kinase), or Ro-31-8220 (protein kinase C inhibitor) or chelating intracellular Ca(2+) with BAPTA-AM failed to attenuate any of the oxLDL effects assayed. Addition to the cultures of WEB 2086, a specific antagonist of the PTX-sensitive G protein-coupled platelet-activating factor (PAF) receptor, blocked the action of oxLDL. Whereas PAF dispersed in the culture medium failed to produce oxLDL-like effects, degradation of PAF and PAF-like phospholipids accumulated in oxLDL with a recombinant human PAF acetylhydrolase eliminated the inhibitory effects of oxLDL on bFGF expression and DNA synthesis.


CONCLUSIONS
OxLDL suppresses endothelial bFGF expression and DNA synthesis through a PTX-sensitive heterotrimeric G-protein pathway involving mediator phospholipids similar, but not identical, to PAF.
Chang
P Y
PY
Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Luo
S
S
Jiang
T
T
Lee
Y T
YT
Lu
S C
SC
Henry
P D
PD
Chen
C H
CH
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002417:Cattle; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D015536:Down-Regulation; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology* / Q000502:physiology; D037342:Pertussis Toxin; D010741:Phospholipases A / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D013449:Sulfonamides; D014230:Triazoles / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D001381:Azepines; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007211:Indoles; D007546:Isoquinolines; D008077:Lipoproteins, LDL; D010972:Platelet Activating Factor; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013449:Sulfonamides; D014230:Triazoles; D010566:Virulence Factors, Bordetella; C099252:oxidized low density lipoprotein; D016222:Fibroblast Growth Factor 2; C052518:WEB 2086; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D019204:GTP-Binding Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C064758:Ro 31-8220