Prostaglandin levels in stimulated macrophages are controlled by phospholipase A2-activating protein and by activation of phospholipase C and D.
Prostaglandins (PG), which are responsible for a large array of biological functions in eukaryotic cells, are produced from arachidonic acid by phospholipases and cyclooxygenase enzymes COX-1 and COX-2. We demonstrated that PG levels in cells were partly controlled by a regulatory protein, phospholipase A2 (PLA2)-activating protein (PLAA). Treatment of murine macrophages with lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha increased PLAA levels at early time points (2-30 min), which correlated with an up-regulation in cytosolic PLA2 and PGE2 levels. Both COX-2 and secretory PLA2 were also increased in lipopolysaccharide-stimulated macrophages, however, at later time points of 4-24 h. The role of PLAA in eicosanoid formation in macrophages was confirmed by the use of an antisense plaa oligonucleotide. Within amino acid residues 503-538, PLAA exhibited homology with melittin, and increased PGE(2) production was noted in macrophages stimulated with melittin. In addition to PLA2, we demonstrated that activation of phospholipase C and D significantly controlled PGE2 production. Finally, increased antigen levels of PLAA, COX-2, and phospholipases were demonstrated in biopsy specimens from patients with varying amounts of intestinal mucosal inflammation, which corresponded to increased levels of phospholipase activity. These results could provide a basis for the development of new therapeutic tools to control inflammation.
Ribardo
D A
DA
Department of Microbiology and Immunology and Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-1070, USA.
Crowe
S E
SE
Kuhl
K R
KR
Peterson
J W
JW
Chopra
A K
AK
D000595:Amino Acid Sequence; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002460:Cell Line; D003092:Colitis / Q000378:metabolism; D003109:Colonic Diseases, Functional / Q000378:metabolism; D003424:Crohn Disease / Q000378:metabolism; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism; D008555:Melitten / Q000494:pharmacology; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis; D011480:Protease Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha; D010738:Type C Phospholipases / Q000378:metabolism*
D018836:Inflammation Mediators; D007375:Interleukin-1; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D016328:NF-kappa B; D011480:Protease Inhibitors; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; C055324:phospholipase A2-activating protein; D008555:Melitten; D016718:Arachidonic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D010738:Type C Phospholipases; D010739:Phospholipase D; D015232:Dinoprostone