Mutant SOD1 from spinal cord of G93A rats is destabilized and binds to inner mitochondrial membrane.
Mutations in Cu/Zn superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS). Mechanisms of mutant SOD1 toxicity are unknown, but increased SOD1 activity can boost production of reactive oxygen species (ROS) in the mitochondrial intermembrane space (IMS). Using non-reducing SDS-PAGE we found that in G93A-SOD1 rats the mutant SOD1 was prominently destabilized only in the diseased spinal cord, where this mutant enzyme was also up regulated in the IMS with increased ability to bind the inner membrane of isolated non-transgenic mitoplasts. These mitoplasts increased ROS production when exposed to mutant SOD1 from the spinal cord at the presymptomatic stage. The levels of disulfide-reduced SOD1 peaked at the end stage of the disease, whereas protein disulfide isomerase (PDI), a chaperone capable of rearranging disulfide bonds between cysteine residues of SOD1, was increased prior to the end stage. IMS binding and increased ROS production by destabilized SOD1 may contribute to mitochondrial damage in G93A-SOD1 rats.
Ahtoniemi
Toni
T
Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland.
Jaronen
Merja
M
Keksa-Goldsteine
Velta
V
Goldsteins
Gundars
G
Koistinaho
Jari
J
D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology* / Q000503:physiopathology; D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology; D051336:Mitochondrial Membranes / Q000201:enzymology*; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D019704:Protein Disulfide-Isomerases / Q000378:metabolism; D051381:Rats; D055647:Rats, Transgenic; D017382:Reactive Oxygen Species / Q000378:metabolism; D013116:Spinal Cord / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation
D050505:Mutant Proteins; D017382:Reactive Oxygen Species; C000606292:Sod1 protein, rat; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019704:Protein Disulfide-Isomerases