Abstract
The synthesis of platelet-activating factor (PAF) by human umbilical vein endothelial cell (HUVEC) in response to H2O2 was significantly increased in a concentration-dependent manner. When HUVEC were pretreated with diethyl maleate, which depletes intracellular glutathione, PAF synthesis was enhanced 3-fold upon 5 mM H2O2-treatment. Intracellular redox was involved in regulating PAF synthesis, since the addition of antioxidants such as N-acetylcysteine, pyrrolidinecarbodithioic acid (PDTC), and Trolox reduced PAF production in H2O2-treated HUVEC. The activity of acetyl-CoA: 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase, which is involved in the last step of PAF synthesis, was also activated in H2O2-treated cells. However, exogenous lyso-PAF addition had not effected to acetyltransferase activity. The acetyltransferase activity responded quickly to H2O2-treatment, but the activation was transitory. A tyrosine kinase inhibitor and a calmodulin antagonist blocked acetyltransferase activity in H2O2-stimulated cells, suggesting that tyrosine kinase and calcium/calmodulin-dependent protein kinase are involved in regulating acetyltransferase activity. These observations suggest that H2O2 is one of the modulators of lyso-PAF acetyltransferase activity via a phosphorylation system and platelet-activating factor (PAF) synthesis.
MeSH terms
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1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / pharmacology
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Acetyltransferases / metabolism*
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Antioxidants / pharmacology
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Arachidonic Acid / metabolism
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Benzylamines / pharmacology
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Calmodulin / antagonists & inhibitors
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Cells, Cultured
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Endothelial Cells / drug effects
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Endothelial Cells / metabolism
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Genistein / pharmacology
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Glutathione / deficiency
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Humans
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Hydrogen Peroxide / pharmacology*
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Maleates / pharmacology
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Oxidants / pharmacology*
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Platelet Activating Factor / biosynthesis
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Protein Kinase C / antagonists & inhibitors
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Protein Kinase Inhibitors / pharmacology
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Protein-Tyrosine Kinases / antagonists & inhibitors
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Sulfonamides / pharmacology
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Umbilical Veins / cytology
Substances
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Antioxidants
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Benzylamines
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Calmodulin
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Maleates
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Oxidants
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Platelet Activating Factor
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Protein Kinase Inhibitors
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Sulfonamides
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KN 93
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Arachidonic Acid
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W 7
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1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
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Hydrogen Peroxide
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Genistein
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Acetyltransferases
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acetyl-CoA-1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase
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Protein-Tyrosine Kinases
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Protein Kinase C
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Calcium-Calmodulin-Dependent Protein Kinase Type 2
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Calcium-Calmodulin-Dependent Protein Kinases
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diethyl maleate
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Glutathione