title: Cytosolic phospholipase A2-mediated regulation of phospholipase D2 in leukocyte cell lines.
abstract: Phospholipase D (PLD) has been implicated in a variety of cellular processes, including inflammation, secretion, and respiratory burst. Two distinct PLD isoforms, designated PLD1 and PLD2, have been cloned; however, the regulatory mechanism for each PLD isoform is not clear. In our present study we investigated how PLD2 activity is regulated in mouse lymphocytic leukemia L1210 cells, which mainly contain PLD2, and in PLD2 -transfected COS-7 cells. Intriguingly, A23187, a calcium ionophore that induces calcium influx, potently stimulates PLD activity in these two cell lines, suggesting that Ca2+ might be implicated in the regulation of the PLD2 activity. In addition to the A23187-induced PLD2 activation, A23187 also increases PLA2-mediated arachidonic acid release, and the A23187-stimulated PLD2 and PLA2 activities could be blocked by pretreatment of the cells with cytosolic calcium-dependent PLA2 (cPLA2) inhibitors, such as arachidonyl trifluoromethyl ketone and methyl arachidonyl fluorophosphonate in these two cell lines. Moreover, the A23187-induced PLD2 and PLA2 activities could be inhibited by cotransfection with antisense cPLA2 oligonucleotide. These results suggest a role for cPLA2 in the regulation of PLD2 activity in vivo. The inhibitory effect of arachidonyl trifluoromethyl ketone on the A23187-induced PLD2 activity could be recovered by addition of exogenous lysophosphatidylcholine. This study is the first to demonstrate that PLD2 activity is up-regulated by Ca2+ influx and that cPLA2 may play a key role in the Ca2+-dependent regulation of PLD2 through generation of lysophosphatidylcholine.
authors.affiliation: National Creative Research Initiative Center for Calcium and Learning, Department of Life Science, School of Environmental Engineering, Pohang University of Science and Technology, South Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: B D
authors.initials: BD
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: S D
authors.initials: SD
authors.lastname: Lee
authors.forename: P G
authors.initials: PG
authors.lastname: Suh
authors.forename: S H
authors.initials: SH
authors.lastname: Ryu
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000494:pharmacology; D019556:COS Cells; D000001:Calcimycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007939:Leukemia L1210; D007941:Leukemia P388; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D051379:Mice; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D054467:Phospholipases A2; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection / Q000187:drug effects; D014407:Tumor Cells, Cultured; D020298:U937 Cells
chemical_list: D001095:Arachidonic Acids; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008244:Lysophosphatidylcholines; D016376:Oligonucleotides, Antisense; C081565:arachidonyltrifluoromethane; D016718:Arachidonic Acid; D000001:Calcimycin; D010741:Phospholipases A; D054467:Phospholipases A2; C105606:phospholipase D2; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate