A subset of patients of amyotrophic lateral sclerosis (ALS) present with mutation of Cu/Zn superoxide dismutase 1 (SOD1), and such mutants caused an ALS-like disorder when expressed in rodents. These findings implicated SOD1 in ALS pathogenesis and made the transgenic animals a widely used ALS model. However, previous studies of these animals have focused largely on motor neuron damage. We report herein that the spinal cords of mice expressing a human SOD1 mutant (hSOD1-G93A), besides showing typical destruction of motor neurons and axons, exhibit significant damage in the sensory system, including Wallerian-like degeneration in axons of dorsal root and dorsal funiculus, and mitochondrial damage in dorsal root ganglia neurons. Thus, hSOD1-G93A mutation causes both motor and sensory neuropathies, and as such the disease developed in the transgenic mice very closely resembles human ALS.
Amyotrophic Lateral Sclerosis/enzymology/*pathology ; Animals ; Axons/*pathology ; Disease Models, Animal ; Ganglia, Spinal/pathology ; Humans ; Mice ; Mice, Transgenic ; Mitochondria/pathology ; Motor Neurons/metabolism/pathology ; Mutation ; Nerve Degeneration/*pathology ; Sensory Receptor Cells/*pathology ; Spinal Cord/*pathology ; Superoxide Dismutase/genetics/*physiology

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the degeneration of motor neurons. Mutations in Cu/Zn superoxide dismutase (SOD1), including G93A, were reportedly linked to familial ALS. SOD1 is a key antioxidant enzyme, and is also one of the major targets for oxidative damage in the brains of patients suffering from Alzheimer's disease (AD). Several lines of evidence suggest that intracellular amyloid beta (Abeta) is associated with the pathogenesis of AD. In this report we demonstrate that intracellular Abeta directly interacts with SOD1, and that this interaction decreases the enzymatic activity of the enzyme. We observed Abeta-SOD1 aggregates in the perinuclear region of H4 cells, and mapped the SOD1 binding region to Abeta amino acids 26-42. Interestingly, intracellular Abeta binds to the SOD1 G93A mutant with greater affinity than to wild-type SOD1. This resulted in considerably less mutant enzymatic activity. Our study implicates a potential role for Abeta in the development of ALS by interacting with the SOD1 G93A mutant.
Amino Acid Sequence ; Amyloid beta-Protein/chemistry/*metabolism ; Amyotrophic Lateral Sclerosis/*enzymology ; Apoptosis ; Cell Line ; Cell Line, Tumor ; Humans ; Molecular Sequence Data ; Point Mutation ; Protein Binding ; Protein Interaction Domains and Motifs ; Superoxide Dismutase/genetics/*metabolism

OBJECTIVETo establish transgenic mouse models of familial amyotrophic lateral sclerosis (FALS) and identify the genotype of the first filial generation.

METHODSSix male B6SJL SOD1G93A/+ hemizygote mice were mated with 6 female B6SJLF1/J+/+ mice to produce the filial generation. The genomic DNA was extracted from the tail vein blood of the first filial generation mice and PCR was performed to amplify the hmSOD1 gene fragment. The genotype of the mice was determined by electrophoresis, and the PCR product was purified for further gene sequence analysis and detection of mutation loci.

RESULTSFifty-three progeny mice were born and the survival rate before ALS onset was 98% (52/53), and among the survived mice, the positivity rate for hmSOD1 gene was 44.2% (23/52). Electrophoresis result showed that the PCR product of 236 bp was consistent with the hmSOD1 gene fragment, and the sequence of the PCR product was identical with hmSOD1 gene sequence of G93A mutant.

CONCLUSIONTransgenic mouse models of ALS can be established in the first filial generation of male B6SJL SOD1G93A/+ mice mated with female B6SJLF1/J+/+. PCR technique can precisely identify the genotype of the filial generation.

Amyotrophic Lateral Sclerosis ; enzymology ; genetics ; pathology ; Animals ; Animals, Newborn ; Base Sequence ; Breeding ; Disease Models, Animal ; Electrophoresis, Agar Gel ; Female ; Genotype ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Inbred Strains ; Mice, Transgenic ; Point Mutation ; Sequence Analysis, DNA ; Superoxide Dismutase ; genetics ; Superoxide Dismutase-1