Journal Article
American Journal of Physiology-Renal Physiology, vol. 273, iss. 4, pp. F507-F515, 1997
Authors
Thomas J. Weber, Terrence J. Monks, Serrine S. Lau
Abstract
Although the exact mechanism of prostaglandin E2(PGE2)-mediated cytoprotection has not been elucidated, its ability to induce cytoprotection in cell culture suggests this action occurs at the cellular level. The present studies were conducted to determine whether PGE2induces protection against 2,3,5-(trisglutathion- S-yl)-hydroquinone [2,3,5-(trisglutathion- S-yl)-HQ]-mediated cytotoxicity in a renal proximal tubule epithelial cell line (LLC-PK1) and to delineate the cellular and molecular mechanisms associated with this response. Pretreatment of LLC-PK1cells with 0.01–40 μM PGE2for 24 h fully protects against a moderately toxic concentration of 2,3,5-(trisglutathion- S-yl)-HQ. PGE2-mediated cytoprotection is observed in cells pretreated at pH 7.4 but not at pH 7.8. However, cytoprotection is observed in LLC-PK1cells pretreated with the PGE2analog, 11-deoxy-16,16-dimethyl PGE2(DDM-PGE2) but not with the PGE2receptor [E-prostanoid (EP)] agonists 17-phenyltrinor PGE2(EP1), 11-deoxy PGE1(EP2/EP4), sulprostone (EP1/EP3), PGE1, or PGA2. 12- O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C (PKC), also induces cytoprotection, supporting a role for this pathway in the cytoprotective response. PGE2, DDM-PGE2, and TPA all induce the binding of nuclear proteins to a TPA responsive element (TRE), whereas analogs that did not induce cytoprotection (PGE1, 17-phenyltrinor PGE2, sulprostone) were without effect. DDM-PGE2- and TPA-mediated cytoprotection and TRE binding activity are inhibited by N-(2{[3-(4-bromophenyl)-2-propenyl]-amino}-ethyl)-5-isoquinolinesulfonamide (H-89), a PKC inhibitor. These data suggest that cytoprotection by PGE2and DDM-PGE2in LLC-PK1cells is mediated by a PKC-coupled receptor, which is pharmacologically distinct from the presently classified EP receptor subtypes.
