Induction of motor neuron apoptosis by free 3-nitro-L-tyrosine.
Peroxynitrite-dependent tyrosine nitration has been postulated to be involved in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Evidence supporting this supposition includes the appearance of both free and protein-linked 3-nitro-l-tyrosine (nitrotyrosine) in both sporadic and familial ALS, as well as of increased free nitrotyrosine levels in the spinal cord of transgenic mice expressing ALS-linked superoxide dismutase mutants at symptom onset. Here we demonstrate that incubation with clinically relevant concentrations of nitrotyrosine induced apoptosis in motor neurons cultured with trophic factors. Nitrotyrosine was bound to proteins, but it was not incorporated into alpha-tubulin, as previously demonstrated for other cell types. Neither inhibition of nitric oxide production nor scavenging of superoxide and peroxynitrite prevented increases in cell nitrotyrosine immunoreactivity or motor neuron death, suggesting that these effects are not due to the endogenous formation of reactive nitrogen species. In contrast, some populations of astrocytes incorporated nitrotyrosine into alpha-tubulin, but free nitrotyrosine had no effect on the viability and phenotype of astrocytes in culture, as evaluated by glial fibrillary acidic protein immunoreactivity, cell growth and morphology. Co-culture of motor neurons on astrocyte monolayers delayed, but did not prevent, nitrotyrosine-induced motor neuron death. These results suggest that free nitrotyrosine may play a role in the induction of motor neuron apoptosis in ALS.
Peluffo
Hugo
H
Departmentos de Histologia y Embriologìa, Facultdad de Medicina, Universidad de la Republica, Montevideo, Uruguay.
Shacka
John J
JJ
Ricart
Karina
K
Bisig
C Gaston
CG
Martìnez-Palma
Laura
L
Pritsch
Otto
O
Kamaid
Andrès
A
Eiserich
Jason P
JP
Crow
John P
JP
Barbeito
Luis
L
Estèvez
Alvaro G
AG
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008665:Metalloporphyrins / Q000494:pharmacology; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D014404:Tubulin / Q000187:drug effects / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000494:pharmacology*
D019208:Brain-Derived Neurotrophic Factor; D016166:Free Radical Scavengers; D005904:Glial Fibrillary Acidic Protein; D008665:Metalloporphyrins; D014404:Tubulin; C473248:iron 5,10,15,20-tetrakis-4-carboxyphenylporphyrin; C002744:3-nitrotyrosine; D014443:Tyrosine