N-octyl-β-valienamine up-regulates activity of F213I mutant β-glucosidase in cultured cells:: a potential chemical chaperone therapy for Gaucher disease

Gaucher disease (GD) is the most common form of sphingolipidosis and is caused by a defect of beta-glucosidase (beta-Glu). A carbohydrate mimic N-octyl-beta-valienamine (NOV) is an inhibitor of beta-Glu. When applied to cultured GD fibroblasts with F213I beta-Glu mutation, NOV increased the protein level of the mutant enzyme and up-regulated cellular enzyme activity. The maximum effect of NOV was observed in F213I homozygous cells in which NOV treatment at 30 muM for 4 days caused a similar to 6-fold increase in the enzyme activity, up to similar to 80% of the activity in control cells. NOV was not effective in cells with other beta-Glu mutations, N370S, L444P, 84CG and RecNcil. Immunofluorescence and cell fractionation showed localization of the F213I mutant enzyme in the lysosomes of NOV-treated cells. Consistent with this, NOV restored clearance of C-14-labeled glucosylceramide in F213I homozygous cells. F213I mutant beta-Glu rapidly lost its activity at neutral pH in vitro and this pH-dependent loss of activity was attenuated by NOV These results suggest that NOV works as a chemical chaperone to accelerate transport and maturation of F213I mutant beta-Glu and may suggest a therapeutic value of this compound for GD. (C) 2004 Elsevier B.V. All rights reserved.