RESUMO
Embryonic motoneurons from mutant SOD1 (mSOD1) mouse models of amyotrophic lateral sclerosis (ALS), but not wild-type motoneurons, can be triggered to die by exposure to nitric oxide (NO), leading to activation of a motoneuron-specific signaling pathway downstream of the death receptor Fas/CD95. To identify effectors of mSOD1-dependent cell death, we performed a proteomic analysis. Treatment of cultured mSOD1 motoneurons with NO led to a 2.5-fold increase in levels of collapsin response mediator protein 4a (CRMP4a). In vivo, the percentage of mSOD1 lumbar motoneurons expressing CRMP4 in mSOD1 mice increased progressively from presymptomatic to early-onset stages, reaching a maximum of 25%. Forced adeno-associated virus (AAV)-mediated expression of CRMP4a in wild-type motoneurons in vitro triggered a process of axonal degeneration and cell death affecting 60% of motoneurons, whereas silencing of CRMP4a in mSOD1 motoneurons protected them from NO-induced death. In vivo, AAV-mediated overexpression of CRMP4a but not CRMP2 led to the death of 30% of the lumbar motoneurons and an 18% increase in denervation of neuromuscular junctions in the gastrocnemius muscle. Our data identify CRMP4a as a potential early effector in the neurodegenerative process in ALS.
Assuntos
Esclerose Lateral Amiotrófica , Neurônios Motores/metabolismo , Degeneração Neural/genética , Proteínas do Tecido Nervoso/metabolismo , Superóxido Dismutase/genética , Regulação para Cima/genética , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Axônios/fisiologia , Morte Celular/genética , Células Cultivadas , Modelos Animais de Doenças , Eletroporação/métodos , Embrião de Mamíferos , Proteínas de Fluorescência Verde/genética , Humanos , Camundongos , Camundongos Mutantes , Neurônios Motores/patologia , Degeneração Neural/etiologia , Proteínas do Tecido Nervoso/genética , Óxido Nítrico/farmacologia , Proteômica/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Medula Espinal/citologia , Regulação para Cima/efeitos dos fármacos , Proteínas Vesiculares de Transporte de Acetilcolina/metabolismoRESUMO
We report on two sisters with a childhood-onset form of predominantly axial dystonia with marked diurnal fluctuations. Onset of clinical features was at approximately 6 years of age. Associated features included marked fatigue, slight facial dysmorphism, short stature, obesity, and learning disability*. Dystonia and fatigue responded to 3,4-dihydroxyphenylalanine (DOPA) therapy, with recurrence of symptoms upon withdrawal; the efficacy has been maintained over 7 years. Other symptoms were not influenced. There was no other case in the family (which included an older, healthy brother), except for non-specific fatigue without dystonia in the mother, and there was no significant family history except for obesity on the father's side. These observations are discussed in relation to the classical descriptions of Segawa syndrome, and to more recent reports of childhood onset, age-related, and transient benign paroxysmal tonic upgaze and ataxia. The combination of symptoms, their sensitivity to DOPA, and their persistence throughout childhood constitute, to our knowledge, a new clinical entity, which we propose to categorize as a DOPA-sensitive dystonia-plus syndrome.
