title: Effects of phenyl saligenin phosphate on cell viability and transglutaminase activity in N2a neuroblastoma and HepG2 hepatoma cell lines.
abstract: The main aim of this study was to determine whether sub-lethal concentrations of the organophosphate compound phenyl saligenin phosphate (PSP) could disrupt the activity of the Ca(2+)-activated enzyme tissue transglutaminase (TGase 2) from cultured cell lines of neuronal (N2a) and hepatic (HepG2) origin. The results indicated that PSP added directly to cytosol extracts from healthy cells was able to inhibit TGase 2 activity by 40-60% of control levels at sub-lethal concentrations (0.1 microM) that were approximately 100-fold lower than their IC(50) values in cytotoxicity assays. Following 24h exposure of N2a cells to 0.3 and 3 microM PSP in situ, a similar reduction in activity was observed in subsequent assays of TGase 2 activity. However, significantly increased activity was observed following in situ exposure of HepG2 cells to PSP (ca. 4-fold at 3 microM). Western blotting analysis indicated slightly reduced levels of TGase 2 in N2a cells compared to the control, whereas an increase was observed in the level of TGase 2 in HepG2 cells. We suggest that TGase 2 represents a potential target of organophosphate toxicity and that its response may vary in different cellular environments, possibly affected by its expression pattern.
authors.affiliation: Natural Sciences Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, United Kingdom.
authors.forename: W
authors.initials: W
authors.lastname: Harris
authors.forename: D
authors.initials: D
authors.lastname: Muñoz
authors.forename: P L R
authors.initials: PL
authors.lastname: Bonner
authors.forename: A J
authors.initials: AJ
authors.lastname: Hargreaves
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors*; D056945:Hep G2 Cells; D006801:Humans; D008099:Liver / Q000187:drug effects*; D051379:Mice; D009447:Neuroblastoma / Q000473:pathology; D009474:Neurons / Q000187:drug effects*; D009943:Organophosphorus Compounds / Q000633:toxicity*; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases / Q000037:antagonists & inhibitors*
chemical_list: D009943:Organophosphorus Compounds; C046357:phenylsaligenin cyclic phosphate; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins