New insights into the pharmacological chaperone activity of c2-substituted glucoimidazoles for the treatment of Gaucher disease.

Mutations in acid β-glucocerebrosidase (GCase) lead to the accumulation of the sphingolipid glucosylceramide, thereby resulting in Gaucher disease (GD). Active-site-specific competitive GCase inhibitors are effective pharmacological chaperones (PCs) that act as folding agents for mutant GCase folding in the endoplasmic reticulum. In this study, we prepared a series of glucoimidazole C2-substituent derivatives, and evaluated their inhibition and PC properties with GCase. A cell-based assay with patient-derived lymphoblasts (N370S or L444P mutations) demonstrated that administration of these compounds can significantly increase GCase activity. Interestingly, the 3,3-dimethyl-N-phenyl-4-amide-1-butyl-substituted moderate inhibitor 11 had the greatest effect on activity: 2.1-fold increase in N370S lymphoblasts at 2.5 μM and 1.2-fold increase in L444P at 0.5 μM following a three-day incubation. Computer docking studies and a protease protection assay were used to elucidate the ligand-enzyme interactions responsible for the chaperone activity of 11. Western blot and immuno-fluorescence assays verified restoration of GCase trafficking to the lysosome. Together, these results indicate that 11 is a promising PC for GD treatment and provide direct evidence of the mechanism of GCase chaperoning.