Genetically decreased spinal cord copper concentration prolongs life in a transgenic mouse model of amyotrophic lateral sclerosis

Mutations in the Cu/Zn superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (FALS) by gain of an aberrant function that is not yet well understood. The role of Cu²⁺ in mediating the toxicity of mutant SOD1 has been earnestly contested. We tested the in vivo effects of genetically induced copper deprivation on the ALS phenotype of transgenic mice expressing G86R mutant mouse SOD1, a protein that fails to incorporate Cu ²⁺ in its active site. Genetically copper-deficient SOD1 ^G86R transgenic mice were produced by mating SOD1^G86R males to female carriers of the X-linked mottled/brindled (Mobr) mutation. We found that the Mobr allele causes a severe (∼60%) depletion of spinal cord copper levels; however, despite the burden of double genetic lesions, it lengthens the lives of SOD1^G86R transgenic mice by 9%. These findings provide evidence supporting a role for copper in the pathogenesis of FALS linked to SOD1 mutations.