Requirement of calcium influx for hydrolytic action of membrane phospholipids by cytosolic phospholipase A2 rather than mitogen-activated protein kinase activation in Fc epsilon RI-stimulated rat peritoneal mast cells.
The mechanism by which cytosolic phospholipase A2 (cPLA2) is not responsible for eicosanoid production in rat peritoneal mast cells upon antigen stimulation [Ishimoto et al. (1996) J. Biochem. 120, 616-623] was investigated in the mast cells stimulated by cross-linking of the IgE receptor or with thapsigargin. Stimulation with thapsigargin, but not with antigen, resulted in apparent lysophosphatidylcholine (lysoPC) formation. Antigen stimulation significantly increased the activities of mitogen-activated protein (MAP) kinase and cPLA2. These activities were further potentiated by phorbol ester. The antigen elicited a rapid and transient increase in intracellular Ca2+ concentration, while thapsigargin produced a slow and sustained increase. Furthermore, a combination of antigen and thapsigargin rapidly increased and prolonged the intracellular Ca2+ concentration. Under these conditions, lysoPC was apparently generated, whereas it was not in response to antigen alone. These results suggest that a prolonged increase in the intracellular Ca2+ concentration is required for cPLA2 to associate with membranes, thus leading to hydrolysis of membrane phospholipids by the enzyme.
Ishimoto
T
T
Department of Pathological Biochemistry, Kyoto Pharmaceutical University.
Arisato
K
K
Akiba
S
S
Sato
T
T
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology; D004789:Enzyme Activation; D008244:Lysophosphatidylcholines / Q000378:metabolism; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D004140:Dinitrophenols; D008244:Lysophosphatidylcholines; D008563:Membrane Lipids; D010743:Phospholipids; D017455:Receptors, IgE; C034638:dinitrophenyl-bovine serum albumin; D012710:Serum Albumin, Bovine; D019284:Thapsigargin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium