In vitro inhibition and intracellular enhancement of lysosomal alpha-galactosidase A activity in Fabry lymphoblasts by 1-deoxygalactonojirimycin and its derivatives.
Fabry disease is a lysosomal storage disorder caused by deficient lysosomal alpha-galactosidase A (alpha-Gal A) activity. Deficiency of the enzyme activity results in progressive deposition of neutral glycosphingolipids with terminal alpha-galactosyl residue in vascular endothelial cells. We recently proposed a chemical chaperone therapy for this disease by administration of 1-deoxygalactonojirimycin, a potent inhibitor of the enzyme, at subinhibitory intracellular concentrations [Fan, J.-Q., Ishii, S., Asano, N. and Suzuki, Y. (1999) Nat. Med. 5, 112-115]. 1-Deoxygalactonojirimycin served as a specific chaperone for those mutant enzymes that failed to maintain their proper conformation to avoid excessive degradation. In order to establish a correlation between in vitro inhibitory activity and intracellular enhancement activity of the specific chemical chaperone, a series of 1-deoxygalactonojirimycin derivatives were tested for activity with both alpha-Gal A and Fabry lymphoblasts. 1-Deoxygalactonojirimycin was the most potent inhibitor of alpha-Gal A with an IC50 value of 0.04 microM. alpha-Galacto-homonojirimycin, alpha-allo-homonojirimycin and beta-1-C-butyl-deoxygalactonojirimycin were effective inhibitors with IC50 values of 0.21, 4.3 and 16 microM, respectively. N-Alkylation, deoxygenation at C-2 and epimerization at C-3 of 1-deoxygalactonojirimycin markedly lowered or abolished its inhibition toward alpha-Gal A. Inclusion of 1-deoxygalactonojirimycin, alpha-galacto-homonojirimycin, alpha-allo-homonojirimycin and beta-1-C-butyl-deoxygalactonojirimycin at 100 microM in culture medium of Fabry lymphoblasts increased the intracellular alpha-Gal A activity by 14-fold, 5.2-fold, 2.4-fold and 2.3-fold, respectively. Weaker inhibitors showed only a minimum enhancement effect. These results suggest that more potent inhibitors act as more effective specific chemical chaperones for the mutant enzyme, and the potent competitive inhibitors of alpha-Gal A are effective specific chemical chaperones for Fabry disease.
Asano
N
N
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Ishii
S
S
Kizu
H
H
Ikeda
K
K
Yasuda
K
K
Kato
A
A
Martin
O R
OR
Fan
J Q
JQ
D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000795:Fabry Disease / Q000201:enzymology*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D000519:alpha-Galactosidase / Q000037:antagonists & inhibitors*
D004791:Enzyme Inhibitors; D017485:1-Deoxynojirimycin; C090092:migalastat; D006026:Glycoside Hydrolases; D000519:alpha-Galactosidase