Copper and Zinc Metallation Status of Copper-Zinc Superoxide Dismutase from Amyotrophic Lateral Sclerosis Transgenic Mice

• Published in: The Journal of biological chemistry Vol. 286; no. 4; pp. 2795 - 2806
• Main Authors: Lelie, Herman L., Liba, Amir, Bourassa, Megan W., Chattopadhyay, Madhuri, Chan, Pik K., Gralla, Edith B., Miller, Lisa M., Borchelt, David R., Valentine, Joan Selverstone, Whitelegge, Julian P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.01.2011; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Substitution; Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease); Amyotrophic Lateral Sclerosis - genetics; Amyotrophic Lateral Sclerosis - metabolism; Amyotrophic Lateral Sclerosis - pathology; Animals; Brain - metabolism; Brain - pathology; Copper; Copper - metabolism; Disease Models, Animal; Homeostasis; Humans; Metallation; Metals; Mice; Mice, Mutant Strains; Mice, Transgenic; Microbiology; Mutation, Missense; Neurodegeneration; SOD1; Spinal Cord - metabolism; Spinal Cord - pathology; Superoxide Dismutase (SOD); Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Superoxide Dismutase-1; Zinc; Zinc - metabolism; Metallation; Superoxide Dismutase (SOD); Neurodegeneration; Metals; Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease); Homeostasis; Copper; Zinc; SOD1
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.186999

Mutations in the metalloenzyme copper-zinc superoxide dismutase (SOD1) cause one form of familial amyotrophic lateral sclerosis (ALS), and metals are suspected to play a pivotal role in ALS pathology. To learn more about metals in ALS, we determined the metallation states of human wild-type or mutant (G37R, G93A, and H46R/H48Q) SOD1 proteins from SOD1-ALS transgenic mice spinal cords. SOD1 was gently extracted from spinal cord and separated into insoluble (aggregated) and soluble (supernatant) fractions, and then metallation states were determined by HPLC inductively coupled plasma MS. Insoluble SOD1-rich fractions were not enriched in copper and zinc. However, the soluble mutant and WT SOD1s were highly metallated except for the metal-binding-region mutant H46R/H48Q, which did not bind any copper. Due to the stability conferred by high metallation of G37R and G93A, it is unlikely that these soluble SOD1s are prone to aggregation in vivo, supporting the hypothesis that immature nascent SOD1 is the substrate for aggregation. We also investigated the effect of SOD1 overexpression and disease on metal homeostasis in spinal cord cross-sections of SOD1-ALS mice using synchrotron-based x-ray fluorescence microscopy. In each mouse genotype, except for the H46R/H48Q mouse, we found a redistribution of copper between gray and white matters correlated to areas of high SOD1. Interestingly, a disease-specific increase of zinc was observed in the white matter for all mutant SOD1 mice. Together these data provide a picture of copper and zinc in the cell as well as highlight the importance of these metals in understanding SOD1-ALS pathology.