Regulation of delayed prostaglandin production in activated P388D1 macrophages by group IV cytosolic and group V secretory phospholipase A2s.
Group V secretory phospholipase A2 (sPLA2) rather than Group IIA sPLA2 is involved in short term, immediate arachidonic acid mobilization and prostaglandin E2 (PGE2) production in the macrophage-like cell line P388D1. When a new clone of these cells, P388D1/MAB, selected on the basis of high responsivity to lipopolysaccharide plus platelet-activating factor, was studied, delayed PGE2 production (6-24 h) in response to lipopolysaccharide alone occurred in parallel with the induction of Group V sPLA2 and cyclooxygenase-2 (COX-2). No changes in the level of cytosolic phospholipase A2 (cPLA2) or COX-1 were observed, and Group IIA sPLA2 was not detectable. Use of a potent and selective sPLA2 inhibitor, 3-(3-acetamide 1-benzyl-2-ethylindolyl-5-oxy)propanesulfonic acid (LY311727), and an antisense oligonucleotide specific for Group V sPLA2 revealed that delayed PGE2 was largely dependent on the induction of Group V sPLA2. Also, COX-2, not COX-1, was found to mediate delayed PGE2 production because the response was completely blocked by the specific COX-2 inhibitor NS-398. Delayed PGE2 production and Group V sPLA2 expression were also found to be blunted by the inhibitor methylarachidonyl fluorophosphonate. Because inhibition of Ca2+-independent PLA2 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 cPLA2 in the response as well. Collectively, the results suggest a model whereby cPLA2 activation regulates Group V sPLA2 expression, which in turn is responsible for delayed PGE2 production via COX-2.
Shinohara
H
H
Department of Chemistry and Biochemistry, School of Medicine and Revelle College, University of California at San Diego, La Jolla, California 92093-0601, USA.
Balboa
M A
MA
Johnson
C A
CA
Balsinde
J
J
Dennis
E A
EA
D000818:Animals; D001483:Base Sequence; D003600:Cytosol / Q000201:enzymology*; D017931:DNA Primers; D004789:Enzyme Activation; D007941:Leukemia P388 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011453:Prostaglandins / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D008070:Lipopolysaccharides; D011453:Prostaglandins; D010741:Phospholipases A; D054467:Phospholipases A2