title: Peroxynitrite transforms nerve growth factor into an apoptotic factor for motor neurons.
abstract: Nerve growth factor (NGF) overexpression and increased production of peroxynitrite occur in several neurodegenerative diseases. We investigated whether NGF could undergo posttranslational oxidative or nitrative modifications that would modulate its biological activity. Compared to native NGF, peroxynitrite-treated NGF showed an exceptional ability to induce p75(NTR)-dependent motor neuron apoptosis at physiologically relevant concentrations. Whereas native NGF requires an external source of nitric oxide (NO) to induce motor neuron death, peroxynitrite-treated NGF induced motor neuron apoptosis in the absence of exogenous NO. Nevertheless, NO potentiated the apoptotic activity of peroxynitrite-modified NGF. Blocking antibodies to p75(NTR) or downregulation of p75(NTR) expression by antisense treatment prevented motor neuron apoptosis induced by peroxynitrite-treated NGF. We investigated what oxidative modifications were responsible for inducing a toxic gain of function and found that peroxynitrite induced tyrosine nitration in a dose-dependent manner. Moreover, peroxynitrite triggered the formation of stable high-molecular-weight oligomers of NGF. Preventing tyrosine nitration by urate abolished the effect of peroxynitrite on NGF apoptotic activity. These results indicate that the oxidation of NGF by peroxynitrite enhances NGF apoptotic activity through p75(NTR) 10,000-fold. To our knowledge, this is the first known posttranslational modification that transforms a neurotrophin into an apoptotic agent.
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable, 11600 Montevideo, Uruguay.
authors.forename: Mariana
authors.initials: M
authors.lastname: Pehar
authors.forename: Marcelo R
authors.initials: MR
authors.lastname: Vargas
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Robinson
authors.forename: Patricia
authors.initials: P
authors.lastname: Cassina
authors.forename: Patrick
authors.initials: P
authors.lastname: England
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Beckman
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
authors.forename: Luis
authors.initials: L
authors.lastname: Barbeito
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D013058:Mass Spectrometry; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020932:Nerve Growth Factor / Q000737:chemistry* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D051381:Rats; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020800:Receptor, Nerve Growth Factor / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D016376:Oligonucleotides, Antisense; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D020800:Receptor, Nerve Growth Factor; D030421:Peroxynitrous Acid; D014443:Tyrosine; D020932:Nerve Growth Factor