Development of enzyme replacement therapy for lysosomal diseases using yeast expression system.

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Efforts have been made to develop therapies for lysosomal diseases including Fabry disease (α-galactosidase deficiency). We have produced a recombinant α-galactosidase with engineered N-linked sugar chains facilitating uptake and transport to lysosomes in a Saccharomyces cerevisiae mutant. We improved the production and purification procedures, allowing us to obtain a large amount of highly purified enzyme protein with mannose-6-phosphate residues at the non-reducing ends of sugar chains. The products were incorporated into cultured fibroblasts derived from a patient with Fabry disease via mannose-6-phosphate receptors. The ceramide trihexoside (CTH) accumulated in lysosomes was cleaved dose-dependently, and the disappearance of deposited CTH was maintained for at least 7 days after administration. We next examined the effect of the recombinant α-galactosidase on Fabry mice. Repeated intravascular administration of the enzyme led to successful degradation of CTH accumulated in the liver, kidneys, heart, and spleen. As the culture of yeast cells is easy and economical, and does not require fetal calf serum, the recombinant α-galactosidase produced in yeast cells is highly promising as an enzyme source for enzyme replacement therapy in Fabry disease.