Toxicity from different SOD1 mutants dysregulates the complement system and the neuronal regenerative response in ALS motor neurons

Global, age-dependent changes in gene expression from rodent models of inherited ALS caused by dominant mutations in superoxicle-dismutase 1 (SOD1) were identified by using gene arrays and RNAs isolated from purified embryonic and adult motor neurons. Comparison of embryonic motor neurons expressing a dismutase active ALS-linked mutant SOD1 with those expressing comparable levels of wild-type SOD1 revealed the absence of mutant-induced mRNA changes. An age-dependent mRNA change that developed presymptomatically in adult motor neurons collected by laser microdissection from mice expressing dismutase active ALS-linked mutants was dysregulation of the D/L-serine biosynthetic pathway, previously linked to both excitotoxic and neurotrophic effects. An unexpected dysregulation common to motor neurons expressing either dismutase active or inactive mutants was induction of neuronally derived components of the classic complement system and the regenerative/injury response. Alteration of these mutant SCD1-induced pathways identified a set of targets for therapies for inherited ALS.