title: DDM-PGE(2)-mediated cytoprotection in renal epithelial cells by a thromboxane A(2) receptor coupled to NF-kappaB.
abstract: The present studies were conducted to determine the pharmacological nature of a cytoprotective 11-deoxy-16,16-dimethyl-PGE(2) (DDM-PGE(2)) receptor in LLC-PK(1) cells. DDM-PGE(2)-mediated cytoprotection against 2,3,5-(trisglutathion-S-yl)hydroquinone (TGHQ)-mediated cytotoxicity can be reproduced using thromboxane A(2) (TXA(2)) receptor (TP) agonists (U46619 and IBOP), and the cytoprotective response to DDM-PGE(2) and TP agonists is inhibited by TP antagonists (SQ-29,548 and ISAP). Western blot analysis using an antipeptide antibody against the human platelet TP receptor (55 kDa) identified a particulate associated 54-kDa protein. DDM-PGE(2)-mediated 12-O-tetradecanoyl phorbol-13-acetate (TPA) responsive element (TRE) binding activity is not inhibited by cyclooxygenase inhibitors (aspirin and indomethacin) or a TXA(2) synthase inhibitor (sulfasalazine), suggesting that the biological response to DDM-PGE(2) is not dependent on de novo TXA(2) biosynthesis. Peak DDM-PGE(2)- and U46619-mediated TRE binding activity and nuclear factor-kappaB (NF-kappaB) binding activity are inhibited by SQ-29,548. The full cytoprotective response to DDM-PGE(2) requires an 8-h pulse with agonist. DDM-PGE(2)-mediated TRE and NF-kappaB binding activity remain elevated in the presence of agonist and rapidly decay following agonist washout, suggesting a direct correlation between DDM-PGE(2)-mediated cytoprotection and persistent DNA binding activities. TPA, a protein kinase C activator, induces cytoprotection and a persistent increase of NF-kappaB binding activity. DDM-PGE(2)-mediated cytoprotection and NF-kappaB binding activity but not TRE binding activity are inhibited by sulfasalazine. We conclude that the DDM-PGE(2) receptor is a TP receptor and that the cytoprotective response may be mediated in part by NF-kappaB.
authors.affiliation: Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712-1074, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Weber
authors.forename: T J
authors.initials: TJ
authors.lastname: Monks
authors.forename: S S
authors.initials: SS
authors.lastname: Lau
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D018374:LLC-PK1 Cells / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000378:metabolism*; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012460:Sulfasalazine / Q000494:pharmacology; D013552:Swine
chemical_list: D000890:Anti-Infective Agents; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D018078:Receptors, Prostaglandin E; D017482:Receptors, Thromboxane; D012460:Sulfasalazine