Calcium-permeable AMPA receptors promote misfolding of mutant SOD1 protein and development of amyotrophic lateral sclerosis in a transgenic mouse model.
Mutant Cu/Zn-superoxide dismutase (SOD1) protein aggregation has been suggested as responsible for amyotrophic lateral sclerosis (ALS), although the operative mediating factors are as yet unestablished. To evaluate the contribution of motoneuronal Ca2+-permeable (GluR2 subunit-lacking) alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors to SOD1-related motoneuronal death, we generated chat-GluR2 transgenic mice with significantly reduced Ca2+-permeability of these receptors in spinal motoneurons. Crossbreeding of the hSOD1G93A transgenic mouse model of ALS with chat-GluR2 mice led to marked delay of disease onset (19.5%), mortality (14.3%) and the pathological hallmarks such as release of cytochrome c from mitochondria, induction of cox2 and astrogliosis. Subcellular fractionation analysis revealed that unusual SOD1 species first accumulated in two fractions dense with neurofilaments/glial fibrillary acidic protein/nuclei and mitochondria long time before disease onset, and then concentrated into the former fraction by disease onset. All these processes for unusual SOD1 accumulation were considerably delayed by GluR2 overexpression. Ca2+-influx through atypical motoneuronal AMPA receptors thus promotes a misfolding of mutant SOD1 protein and eventual death of these neurons.
Laboratory for Motor System Neurodegeneration, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan.
Minako
M
Tateno
Hisako
H
Sadakata
Mika
M
Tanaka
Shigeyoshi
S
Itohara
Ryong-Moon
RM
Shin
Masami
M
Miura
Masao
M
Masuda
Toshihiko
T
Aosaki
Makoto
M
Urushitani
Hidemi
H
Misawa
Ryosuke
R
Takahashi
D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D003433:Crosses, Genetic; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000201:enzymology / Q000473:pathology; D009046:Motor Neurons / Q000201:enzymology / Q000473:pathology; D009154:Mutation / Q000235:genetics*; D017510:Protein Folding; D018091:Receptors, AMPA / Q000235:genetics / Q000502:physiology*; D013116:Spinal Cord / Q000201:enzymology / Q000473:pathology; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D000072105:Superoxide Dismutase-1
D018091:Receptors, AMPA; C000606290:SOD1 protein, human; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C104722:glutamate receptor ionotropic, AMPA 2; D002118:Calcium