Phospholipase D is involved in cytosolic phospholipase A2-dependent selective release of arachidonic acid by fMLP-stimulated rat neutrophils.
When rat polymorphonuclear neutrophils (PMN) were treated with N-formyl-Met-Leu-Phe (fMLP), the release of arachidonic acid in preference to other fatty acids was observed. Levels of arachidonic acid reached a plateau within 5 min, and were accompanied by an approximately 4-fold increase in in vitro phospholipase (PL) A2 and PLD activities in PMN lysates. Treatment of PMN with ethanol (an inhibitor of PLD-mediated phosphatidic acid formation), propranolol (a phosphatidic acid phosphatase inhibitor), or 4-bromophenacylbromide (a PLA2 inhibitor), each suppressed fMLP-stimulated arachidonate release. Treatment with RHC-80267 (a diacylglycerol lipase inhibitor), however, had no such effect. The cytosolic PLA2 (cPLA2) inhibitor, arachidonoyl trifluoromethyl ketone, suppressed PLA2 activity in PMN homogenates and arachidonate release by fMLP-treated PMN. These results suggest that fMLP-elicited arachidonate release is mediated by cPLA2 but not diacylglycerol lipase, and that the activation of cPLA2 is downstream of the PLD-dependent signaling pathway.
Department of Biological Science, Kaken Pharmaceutical Co., Ltd., Shizuoka, Japan.
K
K
Fujita
M
M
Murakami
F
F
Yamashita
K
K
Amemiya
I
I
Kudo
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007659:Ketones / Q000494:pharmacology*; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D010739:Phospholipase D / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000098:Acetophenones; D004791:Enzyme Inhibitors; D007659:Ketones; D016718:Arachidonic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011433:Propranolol; D010741:Phospholipases A; D054467:Phospholipases A2; D010739:Phospholipase D; C006821:4-bromophenacyl bromide