Regulation and function of COX-2 gene expression in isolated gastric parietal cells.
We examined expression, function, and regulation of the cyclooxygenase (COX)-2 gene in gastric parietal cells. COX-2-specific mRNA was isolated from purified (>95%) canine gastric parietal cells in primary culture and measured by Northern blots using a human COX-2 cDNA probe. Carbachol was the most potent inducer of COX-2 gene expression. Gastrin and histamine exhibited minor stimulatory effects. Carbachol-stimulated expression was inhibited by intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM (90%), protein kinase C (PKC) inhibitor GF-109203X (48%), and p38 kinase inhibitor SB-203580 (48%). Nuclear factor (NF)-kappaB inhibitor 1-pyrrolidinecarbodithioic acid inhibited carbachol-stimulated expression by 80%. Similar results were observed in the presence of adenoviral vector Ad.dom.neg.IkappaB, which expresses a repressor of NF-kappaB. Addition of SB-203580 with Ad.dom.neg.IkappaB almost completely blocked carbachol stimulation of COX-2 gene expression. We examined the effect of carbachol on PGE(2) release by enzyme-linked immunoassay. Carbachol induced PGE(2) release. Ad.dom.neg.IkappaB, alone or with SB-203580, produced, respectively, partial (70%) and almost complete (>80%) inhibition of carbachol-stimulated PGE(2) production. Selective COX-2 inhibitor NS-398 blocked carbachol-stimulated PGE(2) release without affecting basal PGE(2) production. In contrast, indomethacin inhibited both basal and carbachol-stimulated PGE(2) release. Carbachol induces COX-2 gene expression in the parietal cells through signaling pathways that involve intracellular Ca(2+), PKC, p38 kinase, and activation of NF-kappaB. The functional significance of these effects seems to be stimulation of PGE(2) release.
Pausawasdi
Nonthalee
N
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 47109-0682, USA.
Ramamoorthy
Saravanan
S
Crofford
Leslie J
LJ
Askari
Frederick K
FK
Todisco
Andrea
A
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D018679:Cholinergic Agonists / Q000494:pharmacology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics*; D008301:Maleimides / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology; D010295:Parietal Cells, Gastric / Q000166:cytology / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D011453:Prostaglandins / Q000096:biosynthesis; D011725:Pyridines / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology
D018679:Cholinergic Agonists; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D016328:NF-kappa B; D009578:Nitrobenzenes; D011453:Prostaglandins; D011725:Pyridines; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D006632:Histamine; D002217:Carbachol; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C070515:bisindolylmaleimide I; C093642:SB 203580