Biochemical and molecular studies of Gaucher's disease

Gaucher's disease accumulated a large amount of glucosylsphingosine as well as glucosylceramide. The accumulation of glucosylsphingosine in tissues of Gaucher's disease was demonstrated as an NBD-F autofluorescent compound, using an HPLC equipped with a Showdex column. An amount of glucosylsphingosine in spleen, kidney and brain tissues of patients with Gaucher's disease was at least 100- to 1,000-fold that of control, since in control psychosine content was practically absent. This novel procedure is useful for the pathochemical evaluation in Gaucher's disease. We further studied the effects of glucosylsphingosine on C6 glioma cells. The addition of glucosylsphingosine had a most potent cytotoxic effect on C6 cells, compared with those of galactosylsphingosine, lysosulfatide and lysophosphatidyl ethanolamine (TD50; 10-20 μg/ml medium). Below a concentration of 10 μg/ml medium, the addition of glucosylsphingosine stimulated cell proliferation. The accumulation of glucosylsphingosine in brain may contribute neuronal cell death in Gaucher's disease. Next, we identified two common mutations in the glucocerebrosidase (GC) gene from 8 Japanese patients with Gaucher's disease. The mutation of 444 Leu to Pro was found in each type of Japanese Gaucher's disease. The mutation of 370 Asn to Ser was not found in Japanese Gaucher's disease. We found the new T to A single substitution (213 Phe to Ile) in exon 6 of the GC gene. By ASO hybridization analysis, this mutation was also detected in 3 out of 6 neuronopathic Japanese cases with Gaucher's disease (type II and III). Thus, this new mutation is considered to be rather common in neuronopathic Japanese Gaucher's disease.