Delayed release of prostaglandins from arachidonic acid and kinetic changes in prostaglandin H synthase activity on the induction of prostaglandin H synthase-2 after lipopolysaccharide-treatment of RAW264.7 macrophage-like cells.
In a mouse macrophage-like cell line, RAW264.7, arachidonic acid was cleaved within 30 min of lipopolysaccharide (LPS)-treatment. However, prostaglandin (PG) synthesis did not accompany this cleavage, being delayed by 4 h, although significant PGH synthase (PGHS) activity was detected in the lysate of LPS-nontreated cells. The K(m) value of this basal PGHS activity toward arachidonic acid was more than one hundred-fold higher than that for the lysate of cells treated with LPS for 4 h. Changes in the sensitivity of the PGHS activity to nonsteroidal antinflammatory drugs after LPS-treatment also suggested induction of PGHS with different properties from that in the case of basal PGHS. The concomitant increase in PGH synthase (PGHS) activity with the induction of PGHS-2 protein after LPS-treatment suggested a contribution by PGHS-2 to the delayed synthesis of PGs in LPS-treated macrophage cells. As for PGHS in the control cells without LPS-treatment, a different K(m) value from that of PGHS-1 and the lack of cross-reactivity to anti-PGHS-1 antibodies suggested that this basal PGHS was different from the typical PGHS-1. The lower affinity of this enzyme for arachidonic acid might be the reason for the failure to release PGs by the cells without LPS-treatment.
Tanaka
Y
Y
Department of Biochemistry and Cell Biology, National Institute of Health, Tokyo, Japan.
Takahashi
M
M
Kawaguchi
M
M
Amano
F
F
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism*; D002460:Cell Line; D004790:Enzyme Induction; D004926:Escherichia coli; D007052:Ibuprofen / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis / Q000378:metabolism*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000378:metabolism*; D011453:Prostaglandins / Q000096:biosynthesis*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007527:Isoenzymes; D008070:Lipopolysaccharides; D011453:Prostaglandins; D016718:Arachidonic Acid; D011451:Prostaglandin-Endoperoxide Synthases; D007052:Ibuprofen; D007213:Indomethacin