Phorbol ester plus calcium ionophore induces release of arachidonic acid from membrane phospholipids of a human B cell line.
Binding of LA350, a lymphoblastoid human B cell line, by phorbol myristate acetate (PMA) plus a calcium ionophore, either ionomycin or A23187, produced unique alterations in the release of arachidonic acid (AA) from cellular phospholipids. After equilibrium labeling of cells with radioactive fatty acids, [14C]AA demonstrated a selective enhanced release from the cells in response to the binding of PMA plus calcium ionophore as compared to the release of [14C]stearic acid (STE), [3H]oleic acid (OLE) and [3H]palmitic acid (PAL). The major phospholipid sources of the released [14C]AA were shown to be phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. The participation of protein kinase C (PKC) in the enhanced synergistic release of [14C]AA was demonstrated by the inhibition of the release by the PKC inhibitor, staurosporine. Approximately 2-6% of the labeled AA liberated was converted to 5-hydroxyeicosatetraenoic acid by an endogenous 5-lipoxygenase. Therefore during cell activation the B cell is capable of liberating AA via a PKC-dependent mechanism, implicating AA and/or its metabolites in signal transduction.
Gilliam
E B
EB
Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030.
Schulam
P G
PG
Whelan
J P
JP
Rosenblatt
H M
HM
Shearer
W T
WT
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology*; D002460:Cell Line; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D011493:Protein Kinase C / Q000502:physiology; D013229:Stearic Acids / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D008563:Membrane Lipids; D010743:Phospholipids; D013229:Stearic Acids; D016718:Arachidonic Acid; D000001:Calcimycin; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; C031183:stearic acid; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate