The priming effect of 12(S)-hydroxyeicosatetraenoic acid on lymphocyte phospholipase D involves specific binding sites.
We have previously shown that 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE)-enrichment primed human peripheral blood mononuclear cells for phospholipase D activation by mitogens. Given that 12(S)-HETE-enriched cells stimulated with concanavalin A released free 12(S)-HETE in the extracellular medium, and that the priming effect of 12(S)-HETE on phospholipase D was suppressed by the non-permeant drug, suramin, we hypothesized an extracellular mechanism for 12(S)-HETE-induced PLD activation. Using [3H]12(S)-HETE as a ligand and a rapid filtration technique, we have pointed out the presence of specific low-affinity 12(S)-HETE binding sites on intact human mononuclear cells and lymphocytes. [3H]12(S)-HETE binding was efficiently displaced by other monohydroxylated and n-3 fatty acids but not by oleate and arachidonate, and was also significantly inhibited by suramin and pertussis toxin. Furthermore, 12(S)-HETE-induced PLD activation was strongly inhibited by pertussis toxin and genistein, but was not PKC-dependent. In addition, 12(S)-HETE also potentiated the ConA-induced tyrosine phosphorylation of a 46-50 kDa protein, which was inhibited by genistein. Collectively, these results suggest that 12(S)-HETE binding sites on human lymphocytes may be coupled to phospholipase D through pertussis toxin sensitive G-proteins and tyrosine kinases.
Zakaroff-Girard
A
A
INSERM U352, Laboratoire de Biochimie et Pharmacologie, Institut National des Sciences Appliquées de Lyon, Villeurbanne, France.
Dubois
M
M
Gilbert
M
M
Meskini
N
N
Némoz
G
G
Lagarde
M
M
Prigent
A F
AF
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D003208:Concanavalin A / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008214:Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology; D037342:Pertussis Toxin; D010739:Phospholipase D / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D013498:Suramin / Q000494:pharmacology; D014316:Tritium; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005227:Fatty Acids; D009281:Naphthalenes; D010566:Virulence Factors, Bordetella; D014316:Tritium; D003208:Concanavalin A; D019000:Phosphotyrosine; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D013498:Suramin; D019833:Genistein; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010739:Phospholipase D; C058819:calphostin C