title: PGE(2) EP(3) receptor downregulates COX-2 expression in the medullary thick ascending limb induced by hypertonic NaCl.
abstract: We tested the hypothesis that inhibition of EP3 receptors enhances cyclooxygenase (COX)-2 expression in the thick ascending limb (TAL) induced by hypertonic stimuli. COX-2 protein expression in the outer medulla increased approximately twofold in mice given free access to 1% NaCl in the drinking water for 3 days. The increase was associated with an approximate threefold elevation in COX-2 mRNA accumulation and an increase in PGE2 production by isolated medullary (m)TAL tubules from 77.3 ± 8.4 to 165.7 ± 10.8 pg/mg protein. Moreover, administration of NS-398 abolished the increase in PGE2 production induced by 1% NaCl. EP3 receptor mRNA levels also increased approximately twofold in the outer medulla of mice that ingested 1% NaCl. The selective EP3 receptor antagonist L-798106 increased COX-2 mRNA by twofold in mTAL tubules, and the elevation in COX-2 protein induced by 1% NaCl increased an additional 50% in mice given L-798106. COX-2 mRNA in primary mTAL cells increased twofold in response to media made hypertonic by the addition of NaCl (400 mosmol/kg H2O). L-798106 increased COX-2 mRNA twofold in isotonic media and fourfold in cells exposed to 400 mosmol/kg H2O. PGE2 production by mTAL cells increased from 79.3 ± 4.6 to 286.7 ± 6.3 pg/mg protein after challenge with 400 mosmol/kg H2O and was inhibited in cells transiently transfected with a lentivirus short hairpin RNA construct targeting exon 5 of COX-2 to silence COX-2. Collectively, the data suggest that local hypertonicity in the mTAL is associated with an increase in COX-2 expression concomitant with elevated EP3 receptor expression, which limits COX-2 activity in this segment of the nephron.
authors: Department of Pharmacology, New York Medical College, Valhalla, New York; and.
authors: Shoujin
authors: S
authors: Hao
authors: Department of Physiology, Center for Aging and Regeneration, CARE Chile UC, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Alejandra
authors: A
authors: Hernandez
authors: Department of Physiology, Center for Aging and Regeneration, CARE Chile UC, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Mariana
authors: M
authors: Quiroz-Munoz
authors: Department of Physiology, Center for Aging and Regeneration, CARE Chile UC, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Carlos
authors: C
authors: Cespedes
authors: Department of Physiology, Center for Aging and Regeneration, CARE Chile UC, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Carlos P
authors: CP
authors: Vio
authors: Department of Pharmacology, New York Medical College, Valhalla, New York; and nick_ferreri@nymc.edu.
authors: Nicholas R
authors: NR
authors: Ferreri
mesh_terms: D000818:Animals; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D008138:Loop of Henle / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D012965:Sodium Chloride; D013449:Sulfonamides / Q000378:metabolism*; D000096926:Benzenesulfonamides
chemical_list: D051546:Cyclooxygenase 2; D012333:RNA, Messenger; D058308:Receptors, Prostaglandin E, EP3 Subtype; D012965:Sodium Chloride; D013449:Sulfonamides; C000595268:5-bromo-2-methoxy-N-(3-(naphthalen-2-yl-methylphenyl)acryloyl)benzenesulfonamide; D000096926:Benzenesulfonamides
keywords: EP3 receptors, thick ascending limb; cyclooxygenase-2; hypertonic stress; prostaglandin E2