Regulation of the membrane-localized prostaglandin E synthases mPGES-1 and mPGES-2 in cardiac myocytes and fibroblasts.
The proinflammatory mediator cyclooxygenase (COX)-2 and its product PGE(2) are induced in the ischemic heart, contributing to inflammatory cell infiltration, fibroblast proliferation, and cardiac hypertrophy. PGE(2) synthesis coupled to COX-2 involves two membrane-localized PGE synthases, mPGES-1 and mPGES-2; however, it is not clear how these synthases are regulated in cardiac myocytes and fibroblasts. To study this, we used primary cultures of neonatal ventricular myocytes (VM) and fibroblasts (VF) treated with IL-1beta for 24 h. To test for involvement of MAPKs in IL-1beta regulation of mPGES-1 and-2, cells were pretreated with the pharmacological inhibitors of p42/44 MAPK, p38 MAPK, and c-Jun kinase (JNK). mRNA was analyzed by RT-PCR. Protein was analyzed by densitometry of Western blots. mPGES-1 was undetectable in untreated VF but induced by IL-1beta; inhibition of either p42/44 MAPK or JNK, but not p38 MAPK, was almost completely inhibitory. In VM, inhibition of the three MAPKs reduced IL-1beta-stimulated mPGES-1 protein by 70-90%. mPGES-2 was constitutively synthesized in both VM and VF and was not regulated by IL-1beta or MAPKs. Confocal microscopy revealed colocalization of both mPGES-1 and mPGES-2 with COX-2 in the perinuclear area of both VF and VM. Finally, PGE(2) production was higher in VM than VF. Our data show that 1) mPGES-1 is induced in both VF and VM, 2) regulation of mPGES-1 by MAPK family members is different in the two cell types, 3) mPGES-2 is constitutively synthesized in both VM and VF and is not regulated, and 4) mPGES-1 and mPGES-2 are colocalized with COX-2 in both cells. Thus differences in activity of mPGES-1 and COX-2 or coupling of COX-2 with mPGES-1 may contribute to differences in PGE(2) production by myocytes and fibroblasts.
Giannico
Giovanna
G
Hypertension and Vascular Research Division, Department of Medicine, Henry Ford Hospital, 2799 W. Grand Blvd., Detroit, MI 48202-2689, USA.
Mendez
Mariela
M
LaPointe
Margot C
MC
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000201:enzymology* / Q000648:ultrastructure; D007375:Interleukin-1 / Q000494:pharmacology; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000648:ultrastructure; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000201:enzymology; D014018:Tissue Distribution
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C489691:Ptgs2 protein, rat; D020928:Mitogen-Activated Protein Kinases; D000071876:Prostaglandin-E Synthases; C497818:Ptges protein, rat; D015232:Dinoprostone