These authors contributed equally to this work.
Focal dysfunction of the proteasome: a pathogenic factor in a mouse model of amyotrophic lateral sclerosis
Version of Record online: 27 APR 2004
Journal of Neurochemistry
Volume 89, Issue 6, pages 1325–1335, June 2004
How to Cite
Kabashi, E., Agar, J. N., Taylor, D. M., Minotti, S. and Durham, H. D. (2004), Focal dysfunction of the proteasome: a pathogenic factor in a mouse model of amyotrophic lateral sclerosis. Journal of Neurochemistry, 89: 1325–1335. doi: 10.1111/j.1471-4159.2004.02453.x
- Issue online: 27 APR 2004
- Version of Record online: 27 APR 2004
- Received December 3, 2003; revised manuscript received January 18, 2004; accepted January 30, 2004.
- amyotrophic lateral sclerosis;
- motor neuron;
- neurodegenerative disorder;
- SOD-1 [Cu/Zn-superoxide dismutase];
Mutations in the Cu/Zn-superoxide dismutase (SOD-1) gene are responsible for a familial form of amyotrophic lateral sclerosis (fALS). The present study demonstrated impaired proteasomal function in the lumbar spinal cord of transgenic mice expressing human SOD-1 with the ALS-causing mutation G93A (SOD-1G93A) compared to non-transgenic littermates (LM) and SOD-1WT transgenic mice. Chymotrypsin-like activity was decreased as early as 45 days of age. By 75 days, chymotrypsin-, trypsin-, and caspase-like activities of the proteasome were impaired, at about 50% of control activity in lumbar spinal cord, but unchanged in thoracic spinal cord and liver. Both total and specific activities of the proteasome were reduced to a similar extent, indicating that a change in proteasome function, rather than a decrease in proteasome levels, had occurred. Similar decreases of total and specific activities of the proteasome were observed in NIH 3T3 cell lines expressing fALS mutants SOD-1G93A and SOD-1G41S, but not in SOD-1WT controls. Although overall levels of proteasome were maintained in spinal cord of SOD-1G93A transgenic mice, the level of 20S proteasome was substantially reduced in lumbar spinal motor neurons relative to the surrounding neuropil. It is concluded that impairment of the proteasome is an early event and contributes to ALS pathogenesis.