Studies on the turnover of glucocerebrosidase in cultured rat peritoneal macrophages and normal human fibroblasts

The kinetics of glucocerebrosidase synthesis and degradation in rat peritoneal macrophages and in human fibroblasts have been studied using conduritol B epoxide (CBE), an irreversible and specific inhibitor of mammalian glucocerebrosidase. In cultured fibroblasts, higher concentrations of CBE and/or longer times were required for inhibition of glucocerebrosidase than were necessary for inhibition of the macrophage enzyme. However, inhibition of activity in cell extracts from both cell types showed identical time and concentration dependence. After the removal of CBE from cultures, enzyme activity returned to normal with a half-time of 48 h for macrophages and 40 h for fibroblasts. The reappearance of enzyme activity was prevented by an inhibitor of protein synthesis. Both the rate of synthesis and degradation of glucocerebrosidase enzyme protein were independent of the presence of CBE. The calculated rate of degradation of glucocerebrosidase was confirmed using metabolically labelled enzyme in cell cultures. The rate of synthesis for macrophages is 1.8 ng enzyme h-1 mg cell protein-1 and the rate of degradation is 1.4% h-1 (0.014 h-1). These values were 2.0 ng h-1 mg-1 and 0.018 h-1 for fibroblasts

Lysosomal storage disorders

This book describes the nature of the lysosomal dysfunction and diseases as well as potential future treatments and therapies. This is an invaluable resource for researchers in biochemical and molecular genetics, enzyme therapy, and gene transfer

Radiological evidence of early cerebral microvascular disease in young children with Fabry disease

We report on 2 children with Fabry disease who had radiologic evidence of microvascular central nervous system involvement despite the clinical absence of renal, cardiac, or cerebral manifestations. This suggests that treatment with enzyme replacement therapy may be necessary early in the disease to avoid irreversible complications

Lectin-specific targeting of β-glucocerebrosidase to different liver cells via glycosylated liposomes

Galactosylated and mannosylated liposomes were more efficient in transporting liposome-entrapped β-glucocerebrosidase to liver compared to nonglycosylated liposomes. The enzyme entrapped to glycoside-bearing liposomes was found to be cleared at a much faster rate than that entrapped in liposomes having no sugar on their surface. Asialoorosomucoid and hydrolyzed mannan were found to inhibit both the clearance and the uptake of galactosylated and mannosylated liposomes, respectively, supporting involvement of lectin-sugar interaction. Further studies on the uptake of glucocerebrosidase by isolated liver cells revealed that the enzyme entrapped in mannosylated liposomes has much higher affinity for nonparenchymal cells whereas the assimilation of the entrapped enzyme into hepatocytes is clearly favored for liposomes having galactose on their surface