hymecromone and Fabry-Disease

A modified alpha-N-acetylgalactosaminidase (NAGA) with alpha-galactosidase A (GLA)-like substrate specificity was designed on the basis of structural studies and was produced in Chinese hamster ovary cells. The enzyme acquired the ability to catalyze the degradation of 4-methylumbelliferyl-alpha-D-galactopyranoside. It retained the original NAGA's stability in plasma and N-glycans containing many mannose 6-phosphate (M6P) residues, which are advantageous for uptake by cells via M6P receptors. There was no immunological cross-reactivity between the modified NAGA and GLA, and the modified NAGA did not react to serum from a patient with Fabry disease recurrently treated with a recombinant GLA. The enzyme cleaved globotriaosylceramide (Gb3) accumulated in cultured fibroblasts from a patient with Fabry disease. Furthermore, like recombinant GLA proteins presently used for enzyme replacement therapy (ERT) for Fabry disease, the enzyme intravenously injected into Fabry model mice prevented Gb3 storage in the liver, kidneys, and heart and improved the pathological changes in these organs. Because this modified NAGA is hardly expected to cause an allergic reaction in Fabry disease patients, it is highly promising as a new and safe enzyme for ERT for Fabry disease.

Topics: alpha-N-Acetylgalactosaminidase; Amino Acid Substitution; Animals; Binding Sites; Catalysis; Cells, Cultured; CHO Cells; Cricetinae; Cricetulus; Culture Media, Conditioned; Disease Models, Animal; DNA, Complementary; Drug Stability; Enzyme Replacement Therapy; Fabry Disease; Fibroblasts; Fluorescent Dyes; Galactosides; Genetic Vectors; Humans; Hydrogen-Ion Concentration; Hymecromone; Immunohistochemistry; Kidney; Liver; Mice; Mice, Knockout; Models, Molecular; Molecular Weight; Myocardium; Recombinant Proteins; Retroviridae; Transfection; Trihexosylceramides

Activities and multiple forms of alpha-D-galactosidase of human kidney and liver in the normal and in Fabry's disease were comparatively studied using alpha-D-galactoside and alpha-D-fucoside as substrates. By isoelectric focusing alpha-D-galactosidase was shown to exist in multiple forms, one of which possesses both alpha-D-galactosidase and alpha-D-fucosidase activity. In Fabry's disease, caused by a deficiency of alpha-D-galactosidase A, we found only one form of alpha-D-galactosidase, which corresponded to form B (alpha-N-acetylgalactosaminidase) and was also able to split alpha-D-fucoside. Thus, in Fabry's disease the alpha-D-fucosidase profile was virtually unchanged, as compared with the normal. The results obtained indicate that the alpha-D-fucosidase activity is due to the action of alpha-D-galactosidase B, encoded for by an autosomal gene of chromosome 22. We suppose these data could be confirmed by revealing the significant reduction of the alpha-D-fucosidase activity in patients with alpha-N-acetylgalactosaminidase deficiency.

Topics: alpha-Galactosidase; alpha-L-Fucosidase; Chemical Phenomena; Chemistry; Fabry Disease; Galactosidases; Glycosides; Humans; Hymecromone; Isoelectric Focusing; Kidney; Liver; Spleen

It was shown that human alpha-D-galactosidase is represented by multiple forms, only one of which can also split alpha-D-fucoside. Fabry's disease was found to be associated not only with the deficiency of the alpha-D-galactosidase total activity but also with the deficiency of the alpha-D-fucosidase activity. The decrease in the alpha-D-galactosidase activity is due to the lack of two enzyme forms, while the profile of alpha-D-fucosidase multiple forms during isoelectric focusing of human enzyme preparations is modified very little in comparison with the normal one. The deficiency of both enzymes was expressed in most degree in leukocytes as compared to other tissues. The residual activities of alpha-D-galactosidase and alpha-D-fucosidase in leukocytes were equal to 3.5 and 21%, respectively. Since the decrease in the alpha-D-fucosidase activity was not so noticeable as in the alpha-D-galactosidase activity, it may be expected that the determination of the alpha-D-fucosidase activity can no longer be regarded as a reliable test for the diagnosis of Fabry's disease. The data obtained suggest that alpha-D-galactoside and alpha-D-fucoside are split by the same enzyme, the multiple forms of which are characterized by selective specificity towards these substrates.

Topics: alpha-Galactosidase; alpha-L-Fucosidase; Fabry Disease; Galactosidases; Glycosides; Humans; Hymecromone; Isoelectric Focusing; Isoenzymes; Kidney; Leukocytes; Liver; Spleen; Substrate Specificity

A simple and sensitive fluorometric method has been described for the differential determination of the activity of lysosomal alpha-galactosidase A and alpha-galactosidase B. The procedure employs 4-methylumbelliferyl-alpha-D-galactopyranoside as substrate and N-acetylgalactosamine as an inhibitor of alpha-galactosidase B, but not of alpha-galactosidase A to differentiate the two activities. This method was shown to be applicable in the differentiation of the two enzyme activities in human tissues and in the diagnosis of the heterozygous and hemizygous genotypes for Fabry's disease in cultured skin fibroblasts.

Topics: Acetylgalactosamine; Adult; alpha-Galactosidase; alpha-N-Acetylgalactosaminidase; Cells, Cultured; Fabry Disease; Female; Fibroblasts; Galactosidases; Galactosides; Genetic Carrier Screening; Hexosaminidases; Humans; Hymecromone; Lysosomes; Male

We report a new assay for the detection of individuals heterozygous and homozygous for Gaucher's disease which requires relatively small samples of whole blood (0.3 ml), and which determines 4-methylumbelliferyl-beta-D-glucopyranoside:beta-glucosidase activity under conditions optimal for the determination of leukocyte glucocerebroside:beta-glucocereborsidase activity. The procedure involves the preparation of a leukocyte pellet from 50 mul of whole blood by hypotonic lysis of erythrocytes, followed by assay of beta-glucosidase activity at pH 5.5 in the presence of sodium taurocholate (0.6 g/100 ml). The methods described may also prove to be useful for the diagnosis of other diseases of enzyme deficiency which use fluorogenic substrates and leukocytes as a source of enzyme, such as Fabry's disease, Tay-Sachs disease, and generalized gangliosidosis.

Topics: Diagnosis, Differential; Fabry Disease; Gangliosides; Gaucher Disease; Glucosidases; Humans; Hymecromone; Leukocytes; Lipid Metabolism, Inborn Errors; Lipidoses; Methods; Microchemistry; Taurocholic Acid