title: Metabolism of 3-nitrotyrosine induces apoptotic death in dopaminergic cells.
abstract: Intrastriatal injection of 3-nitrotyrosine, which is a biomarker for nitrating oxidants, provokes dopaminergic neuronal death in rats by unknown mechanisms. Herein, we show that extracellular 3-nitrotyrosine is transported via the l-aromatic amino acid transporter in nondopaminergic NT2 cells, whereas in dopaminergic PC12 cells, it is transported by both the l-aromatic amino acid and the dopamine transporters. In both cell lines, 3-nitrotyrosine is a substrate for tyrosine tubulin ligase, resulting in its incorporation into the C terminus of alpha-tubulin. In NT2 cells, incorporation of 3-nitrotyrosine into alpha-tubulin induces a progressive, reversible reorganization of the microtubule architecture. In PC12 cells, 3-nitrotyrosine decreases intracellular dopamine levels and is metabolized by the concerted action of the aromatic amino acid decarboxylase and monoamine oxidase. Intracellular levels of 133 micromol of 3-nitrotyrosine per mole of tyrosine did not alter NT2 viability but induced PC12 apoptosis. The cell death was reversed by caspases and aromatic amino acid decarboxylase and monoamine oxidase inhibitors. 3-Nitrotyrosine induced loss of tyrosine hydroxylase-positive primary rat neurons, which was also prevented by an aromatic amino acid decarboxylase inhibitor. These findings provide a novel mechanism by which products generated by reactive nitrogen species induce dopaminergic neuron death and thus may contribute to the selective neurodegeneration in Parkinson's disease.
authors.affiliation: Stokes Research Institute, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Blanchard-Fillion
authors.forename: Delphine
authors.initials: D
authors.lastname: Prou
authors.forename: Manuela
authors.initials: M
authors.lastname: Polydoro
authors.forename: David
authors.initials: D
authors.lastname: Spielberg
authors.forename: Elpida
authors.initials: E
authors.lastname: Tsika
authors.forename: Zeneng
authors.initials: Z
authors.lastname: Wang
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Hazen
authors.forename: Michael
authors.initials: M
authors.lastname: Koval
authors.forename: Serge
authors.initials: S
authors.lastname: Przedborski
authors.forename: Harry
authors.initials: H
authors.lastname: Ischiropoulos
mesh_terms: D026905:Amino Acid Transport Systems / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism; D016923:Cell Death; D045744:Cell Line, Tumor; D002468:Cell Physiological Phenomena; D002470:Cell Survival; D002477:Cells / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D006801:Humans; D008636:Mesencephalon / Q000166:cytology; D008870:Microtubules / Q000648:ultrastructure; D008995:Monoamine Oxidase / Q000378:metabolism; D009474:Neurons / Q000502:physiology; D009596:Nitrophenols / Q000378:metabolism; D016716:PC12 Cells; D010648:Phenylacetates; D051381:Rats; D014404:Tubulin / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D026905:Amino Acid Transport Systems; D050483:Dopamine Plasma Membrane Transport Proteins; D009596:Nitrophenols; D010648:Phenylacetates; D014404:Tubulin; C026242:4-hydroxy-5-nitrophenyl acetic acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D008995:Monoamine Oxidase; D001142:Aromatic-L-Amino-Acid Decarboxylases; D004298:Dopamine