Lysophosphatidylcholine and 7-oxocholesterol modulate Ca2+ signals and inhibit the phosphorylation of endothelial NO synthase and cytosolic phospholipase A2
| Autor: | Gokce Topal, Annie Brunet, Francine Rendu, Elisabeth Millanvoye-Van Brussel, Valérie Deckert, Thuc Do Pham, Monique David-Dufilho |
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| Rok vydání: | 2004 |
| Předmět: |
Umbilical Veins
Thapsigargin Oxysterol Nitric Oxide Synthase Type III Nitric Oxide Biochemistry Phospholipases A Nitric oxide chemistry.chemical_compound Phospholipase A2 Cytosol Enos Humans Calcium Signaling Phosphorylation Molecular Biology Ketocholesterols Arachidonic Acid Mitogen-Activated Protein Kinase 3 biology Lysophosphatidylcholines Cell Biology biology.organism_classification Lipid Metabolism Enzyme Activation Lipoproteins LDL Phospholipases A2 Lysophosphatidylcholine chemistry biology.protein Arachidonic acid lipids (amino acids peptides and proteins) Endothelium Vascular Mitogen-Activated Protein Kinases Nitric Oxide Synthase Research Article |
| Zdroj: | The Biochemical journal. 380(Pt 2) |
| ISSN: | 1470-8728 |
| Popis: | The oxidation of plasma LDLs (low-density lipoproteins) is a key event in the pathogenesis of atherosclerosis. LPC (lysophosphatidylcholine) and oxysterols are major lipid constitutents of oxidized LDLs. In particular, 7-oxocholesterol has been found in plasma from cardiac patients and atherosclerotic plaque. In the present study, we investigated the ability of 7-oxocholesterol and LPC to regulate the activation of eNOS (endothelial nitric oxide synthase) and cPLA2 (cytosolic phospholipase A2) that synthesize two essential factors for vascular wall integrity, NO (nitric oxide) and arachidonic acid. In endothelial cells from human umbilical vein cords, both 7-oxocholesterol (150 µM) and LPC (20 µM) decreased histamine-induced NO release, but not the release activated by thapsigargin. The two lipids decreased NO release through a PI3K (phosphoinositide 3-kinase)-dependent pathway, and decreased eNOS phosphorylation. Their mechanisms of action were, however, different. The NO release reduction was dependent on superoxide anions in LPC-treated cells and not in 7-oxocholesterol-treated ones. The Ca2+ signals induced by histamine were abolished by LPC, but not by 7-oxocholesterol. The oxysterol also inhibited (i) the histamine- and thapsigargin-induced arachidonic acid release, and (ii) the phosphorylation of both cPLA2 and ERK1/2 (extracellular-signal-regulated kinases 1/2). The results show that 7-oxocholesterol inhibits eNOS and cPLA2 activation by altering a Ca2+-independent upstream step of PI3K and ERK1/2 cascades, whereas LPC desensitizes eNOS by interfering with receptor-activated signalling pathways. This suggests that 7-oxocholesterol and LPC generate signals which cross-talk with heterologous receptors, effects which could appear at early stage of atherosclerosis. |
| Databáze: | OpenAIRE |
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