Regulation of Delayed Prostaglandin Production in Activated P388D1 Macrophages by Group IV Cytosolic and Group V Secretory Phospholipase A2s

• Published in: The Journal of biological chemistry 1999-04, Vol.274 (18), p.12263-12268
• Main Authors: Shinohara, H, Balboa, M A, Johnson, C A, Balsinde, J, Dennis, E A
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Cytosol - enzymology; DNA Primers; Enzyme Activation; Leukemia P388 - metabolism; Lipopolysaccharides - pharmacology; Macrophage Activation; Macrophages - drug effects; Macrophages - metabolism; Mice; Phospholipases A - metabolism; Phospholipases A2; Prostaglandins - biosynthesis; Tumor Cells, Cultured
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.18.12263

Group V secretory phospholipase A 2 (sPLA 2 ) rather than Group IIA sPLA 2 is involved in short term, immediate arachidonic acid mobilization and prostaglandin E 2 (PGE 2 ) production in the macrophage-like cell line P388D 1 . When a new clone of these cells, P388D 1 /MAB, selected on the basis of high responsivity to lipopolysaccharide plus platelet-activating factor, was studied, delayed PGE 2 production (6–24 h) in response to lipopolysaccharide alone occurred in parallel with the induction of Group V sPLA 2 and cyclooxygenase-2 (COX-2). No changes in the level of cytosolic phospholipase A 2 (cPLA 2 ) or COX-1 were observed, and Group IIA sPLA 2 was not detectable. Use of a potent and selective sPLA 2 inhibitor, 3-(3-acetamide 1-benzyl-2-ethylindolyl-5-oxy)propanesulfonic acid (LY311727), and an antisense oligonucleotide specific for Group V sPLA 2 revealed that delayed PGE 2 was largely dependent on the induction of Group V sPLA 2. Also, COX-2, not COX-1, was found to mediate delayed PGE 2 production because the response was completely blocked by the specific COX-2 inhibitor NS-398. Delayed PGE 2 production and Group V sPLA 2 expression were also found to be blunted by the inhibitor methylarachidonyl fluorophosphonate. Because inhibition of Ca 2+ -independent PLA 2 by an antisense technique did not have any effect on the arachidonic acid release, the data using methylarachidonyl fluorophosphonate suggest a key role for the cPLA 2 in the response as well. Collectively, the results suggest a model whereby cPLA 2 activation regulates Group V sPLA 2 expression, which in turn is responsible for delayed PGE 2 production via COX-2.