Effect of Familial Amyotrophic Lateral Sclerosis-associated Cu, Zn-superox-ide Dismutase Mutation on Neural Differentiation in Motor Neuronal Cells

BACKGROUND: Mutations in the human Cu, Zn-superoxide dismutase(SOD1) gene have been identified in some cases of familial amyotrophic lateral sclerosis(ALS). The aim of this study is to delineate the effect of the SOD1 mutation on neural differentiation, and to investigate the mechanism of neuronal death. METHODS: We studied motorneuron-neurob-lastoma hybrid cells(VSC 4.1) expressing wild type or mutant SOD1(G93A, A4V) during differentiation by dibutyryl cAMP and aphidicolin. RESULTS: Mutant cells(G93A) revealed a decreased viability compared with the control cells, mainly in the early stage ofdifferentiation. The release of cytochrome c and increased nuclear fragmentation were observed. However, cell death was not protected by nonselective caspase inhibitor(z-VAD-fmk), but by the antioxi-dant( Trolox). CONCLUSIONS: The results suggest that oxidative stress may be the main mechanism of neuronal death, particularly in the early stage of differentiation.

Impairment of Neurite Formation in Familial ALS-associated Cu, Zn-Superoxide Dismutase Mutant Cells

BACKGROUND: Mutations in the human Cu, Zn-superoxide dismutase (SOD1) gene have been identified in some cases of familial amyotrophic lateral sclerosis (ALS). Neuronal cells with mutant SOD1 gene promoted cell death during differentiation by dibutyryl cAMP and aphidicolin. The aim of this study is to delineate if there is an impairment of the neural differentiation process in mutant SOD1 cells. METHODS: We studied the motoneuron-neuroblastoma hybrid cells (VSC 4.1) expressing wild-type or mutant SOD1 (G93A) during the differentiation by dibutyryl cAMP and aphidicolin. RESULTS: Mutant SOD1 cell (G93A) showed an impairment in the neurite formation. Western blot analysis revealed that the amount of neurofilament decreased before differentiation. A decrease in the amount of MAP-2 is observed during differentiation. CONCLUSIONS: Our results suggest that the impairment in the neurite formation of mutant SOD1 cell (G93A) is a differentiation failure and is associated with neuronal cell death.