Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The concanavalin A staining of cellular glycoproteins and the direct analysis of their sugar chains released by hydrazinolysis revealed that the processing of N-linked sugar chains of some glycoproteins is suppressed by exposure of mouse monocytoid cells P388D1 to dimethyl sulphoxide, which can induce Fc receptor-mediated phagocytosis. To elucidate the significance of altered glycosylation in inducing phagocytosis, the effects of exposure of the cells to processing inhibitors (swainsonine and castanospermine) were examined and it was found that the cells are induced to acquire an ability to ingest IgG-coated sheep red blood cells, depending on the dose of the inhibitors and incubation time. Analysis of the N-linked sugar chains liberated from cellular glycoproteins by hydrazinolysis confirmed that the processing of the sugar chains is suppressed by the two inhibitors as expected. Since no significant alteration was induced in protein synthesis and DNA synthesis after exposure to the inhibitors, it is suggested that the altered glycosylation of cellular glycoproteins may have some direct role in the induction of Fc receptor-mediated phagocytosis. The inhibitors did not affect the binding of the IgG-coated red blood cells to Fc receptors on the cells, non-specific phagocytosis of latex beads, and the contents of lysosomal enzymes, beta-glucuronidase and acid phosphatase. These results suggest that the glycosylation status of cellular glycoproteins influences some specific processes involved in the ingestion of the ligands bound to Fc receptors.
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PMID:Processing inhibition of N-linked sugar chains associated with induction of Fc receptor-mediated phagocytosis in the mouse monocytoid cells. 844 80

Glycosaminoglycan storage begins in prenatal life in patients with mucopolysaccharidosis (MPS). In fact, prenatal hydrops is a common manifestation of MPS VII because of beta-glucuronidase (GUS) deficiency. One way to address prenatal storage might be to deliver the missing enzyme across the placenta into the fetal circulation. Maternal IgG is transported across the placenta by the neonatal Fc receptor (FcRn), which recognizes the Fc domain of IgG and mediates transcytosis from maternal to fetal circulation. We hypothesized that we could exploit this process to deliver corrective enzyme to the fetus. To test this hypothesis, the C-terminal fusion protein, GUS-Fc, was compared with native, untagged, recombinant GUS for clearance from the maternal circulation, delivery to the fetus, and reduction of lysosomal storage in offspring of MPS VII mice. We observed that GUS-Fc, infused into pregnant mothers on embryonic days 17 and 18, was transported across the placenta. Similarly infused untagged GUS was not delivered to the fetus. GUS-Fc plasma enzyme activity in newborn MPS VII mice was 1,000 times that seen after administration of untagged GUS and approximately 100 times that of untreated WT newborns. Reduced lysosomal storage in heart valves, liver, and spleen provided evidence that in utero enzyme replacement therapy with GUS-Fc targeted sites of storage in the MPS VII fetus. We hypothesize that this noninvasive approach could deliver the missing lysosomal enzyme to a fetus with any lysosomal storage disease. It might also provide a method for inducing immune tolerance to the missing enzyme or another foreign protein.
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PMID:Infused Fc-tagged beta-glucuronidase crosses the placenta and produces clearance of storage in utero in mucopolysaccharidosis VII mice. 1854 47

Enzyme replacement therapy is an established means of treating lysosomal storage diseases. Infused enzymes are normally targeted to the lysosomes of affected cells by interactions with cell-surface receptors that recognize carbohydrate moieties such as mannose and mannose 6-phosphate on the enzymes. Therefore, we have investigated alternative strategies to deliver the lysosomal enzyme beta-glucuronidase in the enzyme-deficient mucopolysaccharidosis type VII mouse model. Here we summarize our recent efforts to use nontraditional ways to deliver beta-glucuronidase. First, we used a chimeric protein of the insulin-like growth factor II (IGF-II) fused to beta-glucuronidase to deliver enzyme via the IGF-II binding site on the bifunctional IGF-II/mannose 6-phosphate receptor. Second, we used the 11-amino-acid human immunodeficiency virus (HIV) Tat domain fused to beta-glucuronidase to mediate uptake by absorptive endocytosis. Interaction with heparan sulfate on the cell surface internalizes and delivers the Tat-tagged enzyme to the lysosome via plasma membrane recycling. Third, we created a chimeric beta-glucuronidase fused to the Fc portion of human immunoglobulin G (IgG) Fc, which was transported by the neonatal Fc receptor from the maternal circulation across the placenta to sites of storage in fetal tissues. Finally, periodate treatment was used to eliminate interaction with carbohydrate receptors, creating an enzyme with increased plasma half-life, resulting in transport across the blood-brain barrier and clearance of storage in neurons. These strategies for delivering lysosomal enzymes could also be used to target nonlysosomal proteins or enzymes identified for bioremediation of other conditions.
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PMID:New strategies for enzyme replacement therapy for lysosomal storage diseases. 2034 79


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