Arachidonate release and prostaglandin production by group IVC phospholipase A2 (cytosolic phospholipase A2gamma).
While the role of the group IVA Ca(2+)-dependent cytosolic phospholipase A(2)alpha (cPLA(2)alpha) in arachidonic acid (AA) metabolism has been well documented, that of its paralogue, Ca(2+)-independent group IVC PLA(2) (cPLA(2)gamma), has remained uncertain. Here we show, using a transfection strategy, that cPLA(2)gamma has the ability to increase the spontaneous and stimulus-induced release of cellular fatty acids. The AA released by cPLA(2)gamma was metabolized further to prostaglandin E(2) via cyclo-oxygenase-1 (COX-1) in the immediate response, and via COX-2 in the delayed response. Mutation of the putative catalytic-centre residue Ser(82) abrogated the AA-releasing function of cPLA(2)gamma both in vitro and in vivo. Confocal microscopy revealed that cPLA(2)gamma was distributed in the perinuclear endoplasmic reticulum membranes. Mutating the C-terminal prenylation site of cPLA(2)gamma abrogated its intracellular membrane localization and cellular AA-releasing function, without reducing its enzyme activity in vitro. Our results indicate that cPLA(2)gamma is the second cPLA(2) enzyme that contributes to cellular AA metabolism and phospholipid remodelling under appropriate conditions.
Murakami
Makoto
M
Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. mako@pharm.showa-u.ac.jp
Masuda
Seiko
S
Kudo
Ichiro
I
D019943:Amino Acid Substitution; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001095:Arachidonic Acids / Q000494:pharmacology; D001665:Binding Sites; D015152:Blotting, Northern; D002478:Cells, Cultured; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D003600:Cytosol / Q000201:enzymology; D018076:DNA, Complementary / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D018613:Microscopy, Confocal; D009578:Nitrobenzenes / Q000494:pharmacology; D063065:Organophosphonates / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D013449:Sulfonamides / Q000494:pharmacology; D014162:Transfection / Q000379:methods
D001095:Arachidonic Acids; D018076:DNA, Complementary; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D063065:Organophosphonates; D011453:Prostaglandins; D013449:Sulfonamides; C104810:methyl arachidonylfluorophosphonate; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D016718:Arachidonic Acid; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D010741:Phospholipases A; D054467:Phospholipases A2