title: Dopamine down-regulation of protein L-isoaspartyl methyltransferase is dependent on reactive oxygen species in SH-SY5Y cells.
abstract: Parkinson's disease (PD) is a chronic and progressive neurological disorder that is characterized by the loss of dopaminergic neurons in the substantia nigra. Dopamine, via the oxidative stress that it generates in the cytosol, could contribute to the selective loss of neurons observed in PD. Protein L-isoaspartyl methyltransferase (PIMT) is an enzyme that repairs L-isoaspartyl-containing proteins and possesses anti-apoptotic properties. PIMT expression has been shown to decrease with age. Together, these observations prompted us to investigate whether dopamine can regulate PIMT expression in SH-SY5Y neuroblastoma cells. Here, we report that dopamine down-regulated PIMT at both gene and protein levels. The same inhibition of PIMT protein level was caused by the electron transport chain inhibitor, rotenone, which was accompanied, in both cases, by an increase in cell death and reactive oxygen species (ROS) production. In fact, pre-treatment with the antioxidant N-acetyl cysteine blocked PIMT dopamine-associated down-regulation. PCMT1 promoter mapping experiments allowed the identification of two regions that showed different sensitivity to DA action. A first region localized between 61 and 94bp upstream of transcription start site was very sensitive to dopamine inhibition while a second region between 41 and 61bp appeared more resistant to dopamine inhibitory effect. The inhibition of PCMT1 promoter activity was mediated by dopamine-induced ROS since it was prevented by the hydroxyl radical scavenger N,N'-dimethylthiourea. Conversely, H2O2 inhibited in a dose-dependent manner the transcriptional activity of PCMT1 promoter. Therefore, our findings identified new molecular mechanisms, cytosolic dopamine and its resulting ROS, as inhibitors of PIMT expression. This suggests that ROS generated from cytosolic dopamine could reduce both the PCMT1 gene promoter activity and the PIMT protein level thus decreasing its capacity to repair proteins involved in apoptosis and could contribute to neuronal cell death observed in PD.
authors.affiliation: Université du Québec à Montréal, Département de chimie, C.P. 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Ouazia
authors.affiliation: Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada.
authors.forename: L-C
authors.initials: LC
authors.lastname: Levros
authors.affiliation: Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Rassart
authors.affiliation: Université du Québec à Montréal, Département de chimie, C.P. 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada. Electronic address: desrosiers.r@uqam.ca.
authors.forename: R R
authors.initials: RR
authors.lastname: Desrosiers
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007306:Insecticides / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D009447:Neuroblastoma / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D014162:Transfection
chemical_list: D000975:Antioxidants; D007306:Insecticides; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D018336:Receptors, Aryl Hydrocarbon; D012402:Rotenone; D006861:Hydrogen Peroxide; D002374:Catalase; D026601:Protein D-Aspartate-L-Isoaspartate Methyltransferase; D004298:Dopamine
keywords: PCMT1; PIMT; Parkinson’s disease; dopamine; oxidative stress; protein L-isoaspartyl methyltransferase