To elucidate the molecular mechanisms whereby expanded polyglutamine stretches elicit a gain of toxic function, we expressed full-length and truncated DRPLA (dentatorubral-pallidoluysian atrophy) cDNAs with or without expanded CAG repeats in COS-7 cells. We found that truncated DRPLA proteins containing an expanded polyglutamine stretch form filamentous peri- and intranuclear aggregates and undergo apoptosis. The apoptotic cell death was partially suppressed by the transglutaminase inhibitors cystamine and monodansyl cadaverine (but not putrescine), suggesting involvement of a transglutaminase reaction and providing a potential basis for the development of therapeutic measures for CAG-repeat expansion diseases.

Studies on the clinical course of familial ALS suggest that the duration of illness is relatively consistent for each mutation but variable among the different mutations. The authors analyzed the relative amount of mutant compared with normal SOD1 protein in the erythrocytes from 29 patients with ALS with 22 different mutations. Turnover of mutant SOD1 correlated with a shorter disease survival time.

These findings suggest that the I113T mutation induces accumulation of neurofilaments and SOD1 in the central nervous system neurons.

We describe a new family with adult onset amyotrophic lateral sclerosis (FALS), in which the disease was characterized clinically by relatively rapid progression of bulbar symptoms. Gene analysis of Cu/Zn superoxide dismutase (SOD1) performed in one patient showed no mutations. Autopsy of another patient demonstrated degenerative changes restricted to the upper and lower motor neuron systems; no evident changes were observed in the posterior column, Clarke's column or spinocerebellar tracts. The presence of Bunina bodies and ubiquitin-positive skein-like inclusions in the lower motor neuron was of considerable interest. Cases of FALS with such pathological features are quite rare in the literature. Identification of the gene responsible for the disease is desirable in order to shed further light on the molecular pathology of not only familial, but also sporadic, ALS.

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