title: Reactive oxygen species generated by thiol-modifying phenylarsine oxide stimulate the expression of protein L-isoaspartyl methyltransferase.
abstract: Expression of the repair enzyme protein L-isoaspartyl methyltransferase (PIMT) has been reported to play important roles in brain. However, little is known about the regulation of PIMT expression following protein damage by oxidation in brain. Phenylarsine oxide (PAO) is an arsenical compound that alters proteins by forming disulfide bond with vicinal cysteinyl residues. Here we report that PIMT was rapidly up-regulated by PAO in U-87 human astroglioma cells. We also confirmed that PIMT up-regulation by PAO was mediated by the reaction with vicinal cysteines. Furthermore, we showed that PIMT induction by PAO was dependent on formation of reactive oxygen species (ROS). Crucially, both ROS formation and PIMT induction by PAO were inhibited by antioxidant N-acetyl-L-cysteine and NADPH oxidase inhibitor diphenyleneiodonium chloride. Importantly, down-regulation of PIMT by siRNA strikingly enhanced PAO-induced ROS. Together, these results highlight that PIMT expression is regulated by ROS and could primarily act as an antioxidant enzyme.
authors.affiliation: Université du Québec à Montréal, Département de chimie, C.P. 8888, Succursale Centre-Ville, Montréal, Que., Canada H3C 3P8.
authors.forename: Irvens
authors.initials: I
authors.lastname: Fanélus
authors.forename: Richard R
authors.initials: RR
authors.lastname: Desrosiers
mesh_terms: D001152:Arsenicals / Q000494:pharmacology; D045744:Cell Line, Tumor; D003545:Cysteine / Q000187:drug effects; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D001152:Arsenicals; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C029341:oxophenylarsine; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase; D003545:Cysteine