title: Effect of 12-O-tetradecanoylphorbol-13-acetate on inhibition of expression of keratin 1 mRNA in mouse keratinocytes mimicked by 12(S)-hydroxyeicosatetraenoic acid.
abstract: Differentiation of cultured keratinocytes is controlled by the calcium concentration of the medium and is marked by the expression of differentiation-specific keratins. Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) alters the normal differentiation program and suppresses keratin (K) 1 expression. Based on reported similarities in the effects of TPA and the arachidonic acid metabolite 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), we hypothesized that 12(S)-HETE might suppress K1 expression in mouse keratinocytes. We also investigated the effect of pretreatment with 13(S)-hydroxyoctadecadienoic acid (13(S)-HODE) because others have reported that 13(S)-HODE prevents 12(S)-HETE-induced events. In our study, 100 nM 12(S)-HETE mimicked the effect of 500 nM TPA in suppressing K1 mRNA expression within 24 h of calcium-induced differentiation. Pretreatment with 100 nM 13(S)-HODE blocked the 12(S)-HETE effect but not the TPA effect. A role for protein kinase C (PKC) was suggested for both TPA and 12(S)-HETE based on the loss of response with the PKC inhibitors bryostatin-1 or RO-31-8220. Both TPA and 12(S)-HETE stimulated keratinocyte PKC activity. Pretreatment with 13(S)-HODE blocked the 12(S)-HETE-induced increase in PKC activity. Immunoblotting showed that whereas TPA caused a rapid, partial translocation of the PKC alpha isozyme, it had no effect on the distribution of PKC delta. Conversely, 12(S)-HETE had no effect on the distribution of PKC alpha but caused a complete translocation of PKC delta. Pretreatment with 13(S)-HODE prevented 12(S)-HETE-elicited translocation of PKC delta. We conclude that 12(S)-HETE mimics the effect of TPA on K1 mRNA and that the effect is mediated through different isoforms of PKC.
authors.affiliation: Division of Nutritional Sciences, University of Texas at Austin 78712-1097, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Hagerman
authors.forename: S M
authors.initials: SM
authors.lastname: Fischer
authors.forename: M F
authors.initials: MF
authors.lastname: Locniskar
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D054713:Bryostatins; D002273:Carcinogens / Q000494:pharmacology*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D015603:Keratinocytes / Q000378:metabolism* / Q000502:physiology*; D007633:Keratins / Q000096:biosynthesis*; D007783:Lactones / Q000494:pharmacology; D018942:Macrolides; D051379:Mice; D018632:Mice, Inbred SENCAR; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D012333:RNA, Messenger / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D054713:Bryostatins; D002273:Carcinogens; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D007783:Lactones; D018942:Macrolides; D012333:RNA, Messenger; C046785:bryostatin 1; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D007633:Keratins; C497259:Prkcd protein, mouse; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220