title: NS-398 upregulates constitutive cyclooxygenase-2 expression in the M-1 cortical collecting duct cell line.
abstract: The cortical collecting duct (CCD) is a major site of intrarenal prostaglandin E2 (PGE2) synthesis. This study examines the expression and regulation of the prostaglandin synthesizing enzymes cyclooxygenase-1 (COX-1) and -2 in the CCD. By indirect immunofluorescence using isoform-specific antibodies, COX-1 and -2 immunoreactivity was localized to all cell types of the murine M-1 CCD cell line. By immunohistochemistry, both COX-1 and COX-2 were localized to intercalated cells of the CCD on paraffin-embedded mouse kidney sections. When COX enzyme activity was measured in the M-1 cells, both indomethacin (COX-1 and -2 inhibitor) and the specific COX-2 inhibitor NS-398 effectively blocked PGE2 synthesis. These results demonstrate that COX-2 is the major contributor to the pool of PGE2 synthesized by the CCD. By Western blot analysis, COX-2 expression was significantly upregulated by incubation with either indomethacin or NS-398. These drugs did not affect COX-1 protein expression. Evaluation of COX-2 mRNA expression by Northern blot analysis after NS-398 treatment demonstrated that the COX-2 protein upregulation occurred independently of any change in COX-2 mRNA expression. These studies have for the first time localized COX-2 to the CCD and provided evidence that the intercalated cells of the CCD express both COX-1 and COX-2. The results also demonstrate that constitutively expressed COX-2 is the major COX isoform contributing to PGE2 synthesis by the M-1 CCD cell line. Inhibition of COX-2 activity in the M-1 cell line results in an upregulation of COX-2 protein expression.
authors.affiliation: Department of Cellular and Molecular Medicine, University of Ottawa, Ontario, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Ferguson
authors.forename: R L
authors.initials: RL
authors.lastname: Hébert
authors.forename: O
authors.initials: O
authors.lastname: Laneuville
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002478:Cells, Cultured; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D007672:Kidney Cortex / Q000187:drug effects* / Q000201:enzymology; D007685:Kidney Tubules, Collecting / Q000187:drug effects* / Q000201:enzymology; D008565:Membrane Proteins; D051379:Mice; D009578:Nitrobenzenes / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D013449:Sulfonamides / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D012333:RNA, Messenger; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D015232:Dinoprostone