Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the presence of enzymes on the surface of Drosophila melanogaster spermatozoa that might bind the carbohydrate residues of the egg shell. Spectrophotometric and fluorimetric studies were used on whole spermatozoa to assay galactosyltransferase and glycosidase activities. No galactosyltransferase is present on the sperm surface, whereas two glycosidases, beta-N-acetylglucosaminidase (GlcNAc'ase) and alpha-mannosidase (Man'ase), have been evidenced. They have an optimal pH of 6-6.5 and 4, respectively. The same glycosidases were detected as soluble forms probably secreted by the seminal vesicle epithelium. We suggest that these enzymes might be involved in the recognition of alpha-mannose and beta-N-acetylglucosamine residues present on the egg shell at the site of sperm entry.
Mol Reprod Dev 1997 Oct
PMID:Glycosidases are present on the surface of Drosophila melanogaster spermatozoa. 929 78

Tay-Sachs and Sandhoff diseases are autosomal recessive neurodegenerative diseases resulting from the inability to catabolize GM2 ganglioside by beta-hexosaminidase A (Hex A) due to mutations of the alpha subunit (Tay-Sachs disease) or beta subunit (Sandhoff disease) of Hex A. Hex B (beta beta homodimer) is also defective in Sandhoff disease. We previously developed mouse models of both diseases and showed that Hexa-/- (Tay-Sachs) mice remain asymptomatic to at least 1 year of age while Hexb-/- (Sandhoff) mice succumb to a profound neurodegenerative disease by 4-6 months of age. Here we find that neuron death in Hexb-/- mice is associated with apoptosis occurring throughout the CNS, while Hexa-/- mice were minimally involved at the same age. Studies of autopsy samples of brain and spinal cord from human Tay-Sachs and Sandhoff diseases revealed apoptosis in both instances, in keeping with the severe expression of both diseases. We suggest that neuron death is caused by unscheduled apoptosis, implicating accumulated GM2 ganglioside or a derivative in triggering of the apoptotic cascade.
Hum Mol Genet 1997 Oct
PMID:Apoptotic cell death in mouse models of GM2 gangliosidosis and observations on human Tay-Sachs and Sandhoff diseases. 930 66

Tay-Sachs disease is a severe neurodegenerative disorder due to mutations in the HEXA gene coding for the alpha-chain of the alpha-beta heterodimeric lysosomal enzyme beta-hexosaminidase A (HexA). Because no treatment is available for this disease, we have investigated the possibility of enzymatic correction of HexA-deficient cells by HEXA gene transfer. Human HEXA cDNA was subcloned into a retroviral plasmid generating to G.HEXA vector. The best Psi-CRIP producer clone of G.HEXA retroviral particles was isolated, and murine HexA-deficient fibroblasts derived from hexa -/- mice were transduced with the G.HEXA vector. Transduced cells overexpressed the alpha-chain, resulting in the synthesis of interspecific HexA (human alpha-chain/murine beta-chain) and in a total correction of HexA deficiency. The alpha-chain was secreted in the culture medium and taken up by HexA-deficient cells via mannose-6-phosphate receptor binding, allowing for the restoration of intracellular HexA activity in non-transduced cells.
Hum Mol Genet 1998 May
PMID:Retrovirus-mediated enzymatic correction of Tay-Sachs defect in transduced and non-transduced cells. 953 87

The GM2 gangliosidoses are a group of heritable neurodegenerative disorders caused by excessive accumulation of the ganglioside GM2 owing to deficiency in beta-hexosaminidase activity. Tay-Sachs and Sandhoff diseases have similar clinical phenotypes resulting from a deficiency in human hexosaminidase alpha and beta subunits, respectively. The lack of treatment for GM2 gangliosidoses stimulated interest in developing animal models to understand the molecular mechanisms underlying the various forms of this disease and to test new potential therapies. In this review, we discuss the molecular biology of GM2 gangliosidoses and the different strategies that have been tested in animal models for the treatment of this genetic disorder, including gene transfer and cell engraftment of neural stem cells engineered to express the hexosaminidase isoenzymes.
Mol Med Today 1998 Apr
PMID:Biology and potential strategies for the treatment of GM2 gangliosidoses. 957 57

The mast cell lines rat basophilic leukemia (RBL) and mouse C57 cells respond to IgE/antigen complexes by degranulation. Treatment of these cells with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), (10-100 nM) for 24-48 h enhanced IgE/antigen-induced exocytosis as monitored by release of hexosaminidase. A short term incubation with the hormone did not affect exocytosis, ruling out a rapid non genomic mechanism. The presence of vitamin D receptors, demonstrated by immunoblotting and the lack of effect of 24,25(OH)2D3 suggest a role for these receptors in the enhancing effect. 1,25(OH)2D3 also enhanced exocytosis induced by the calcium ionophore A23187 in the presence or absence of phorbol ester indicating modulation of events distal to signal transduction. 1,25(OH)2D3 enhanced exocytosis in the presence of cytochalasin D, indicating that the action of the hormone is not due to effects on microfilament structure. The results of this study suggest that 1,25(OH)2D3 may affect the allergic or pro-inflammatory potential of mast cells.
Mol Cell Endocrinol 1998 Jul 25
PMID:1,25-Dihydroxyvitamin D3 enhances degranulation of mast cells. 978 2

Two forms of the chitinolytic enzyme N-acetyl-beta-D-glucosaminidase (NAGase, EC 3.2.1.52) have been isolated from the Antarctic krill, Euphausia superba, in order to study their potential role in temperature adaptation processes. A chromatographic protocol was developed that allowed complete separation of the two enzyme forms, named NAGase B and NAGase C. The latter was purified to homogeneity with 600-fold enrichment and a yield of 17%. The molecular mass was 150 kDa. NAGase B showed characteristics of a glycoprotein due to affinity towards concanavalin A sepharose, while NAGase C did not. Highly specific polyclonal antibodies to NAGase C [anti-(E. superba-NAGase C)-IgG] showed only negligible cross-reactivity with NAGase B isoforms. A comparison with the Northern krill, Meganyctiphanes norvegica, revealed a corresponding chromatographic pattern with two main activity peaks, for differentiation named NAGase II and NAGase III. Application of the antibody on M. norvegica revealed a high specificity toward NAGase III and a low cross-reactivity with NAGase II. First indication is given that the two forms are no isoenzymes in a strict sense but instead may have different functions in the metabolism of krill.
Comp Biochem Physiol B Biochem Mol Biol 1998 Aug
PMID:Isoforms of an N-acetyl-beta-D-glucosaminidase from the Antarctic krill, Euphausia superba: purification and antibody production. 985 20

Previous studies have identified beta-N-acetylglucosaminidase (GlcNAc'ase) and (alpha-mannosidase activities on the Drosophila melanogaster sperm surface which may have a role in fertilization. The aim of this study was to investigate their linkage to the sperm plasma membrane. We verified that glycosidases are not peripherally adsorbed to the cell surface by evaluating their resistance to release by KI, by buffered salt solutions of high ionic strength or alkaline buffers. Glycosidases were released from the sperm surface by detergents and, only to a minor extent, by mild proteolysis. Differential detergent solubilization pointed out that Triton X-114 was the most effective releasing agent for GlcNAc'ase and CHAPS for mannosidase. No activity was released from the membrane by a phosphatidylinositol-specific phospholipase C (PI-PLC). The released forms were quite hydrophilic in phase separation experiments with Triton X-114. This finding indicates the presence of a hydrophobic domain limited to a single transmembrane helix or/and the presence of an extensive glycosylation. The use of a Con-A binding assay demonstrated that both the enzymes are glycosylated. The molecular weight of the released glycosidases estimated by gel filtration was 158 kDa for GlcNAc'ase and 317 kDa for mannosidase. These results suggest that Drosophila melanogaster GlcNAc'ase and mannosidase are mannosylated integral membrane proteins that would function as exoenzymes with their active sites accessible in the extracellular space.
Mol Reprod Dev 1999 Feb
PMID:Plasma membrane association and preliminary characterization of Drosophila sperm surface glycosidases. 989 Jul 47

The severe neurodegenerative disorder, Tays-Sachs disease, is caused by a beta-hexosaminidase alpha-subunit deficiency which prevents the formation of lysosomal heterodimeric alpha-beta enzyme, hexosaminidase A (HexA). No treatment is available for this fatal disease; however, gene therapy could represent a therapeutic approach. We previously have constructed and characterized, in vitro, adenoviral and retroviral vectors coding for alpha- and beta-subunits of the human beta-hexosaminidases. Here, we have determined the in vivo strategy which leads to the highest HexA activity in the maximum number of tissues in hexA -deficient knock-out mice. We demonstrated that intravenous co-administration of adenoviral vectors coding for both alpha- and beta-subunits, resulting in preferential liver transduction, was essential to obtain the most successful results. Only the supply of both subunits allowed for HexA overexpression leading to massive secretion of the enzyme in serum, and full or partial enzymatic activity restoration in all peripheral tissues tested. The enzymatic correction was likely to be due to direct cellular transduction by adenoviral vectors and/or uptake of secreted HexA by different organs. These results confirmed that the liver was the preferential target organ to deliver a large amount of secreted proteins. In addition, the need to overexpress both subunits of heterodimeric proteins in order to obtain a high level of secretion in animals defective in only one subunit is emphasized. The endogenous non-defective subunit is otherwise limiting.
Hum Mol Genet 1999 May
PMID:Adenoviral gene therapy of the Tay-Sachs disease in hexosaminidase A-deficient knock-out mice. 1019 72

Late-phase and sustained activation of p44/42(MAPK) has been reported to be a critical factor in cell mitogenesis. We therefore hypothesized that p44/42(MAPK) is involved in mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth-muscle cells (ASMC). Treatment of adherent ASMC with beta-hexosaminidase A (Hex A, 50 nM), an endogenous mannosyl-rich glycoprotein, resulted in a late-onset (30-min) activation of p44/42(MAPK) that lasted for 4 h. Activation of p44/42(MAPK) induced by Hex A was inhibited by an 18-mer phosphorothioate-derivatized antisense oligonucleotide (1-5 microM) directed to human p44(MAPK); the mitogen-activated protein kinase kinase (MEK1) inhibitor PD98059 (5 microM); the p42(MAPK) inhibitor Tyrphostin AG-126 (0.2 microM); the farnesyl transferase inhibitors SCH-56582 (10 microM) and FPT III (10 miroM), which inhibit p21Ras activation; and Calphostin C (0.2 microM), an inhibitor of protein kinase C. These agents also inhibited Hex A-induced cell proliferation in bovine ASMC. These data suggest that Hex A activates p44/42(MAPK) in a p21Ras- and PKC-dependent manner and that this activation mediates Hex A- induced mitogenesis in bovine ASMC.
Am J Respir Cell Mol Biol 1999 Jul
PMID:beta-hexosaminidase-induced activation of p44/42 mitogen-activated protein kinase is dependent on p21Ras and protein kinase C and mediates bovine airway smooth-muscle proliferation. 1038 99

beta-N-Acetylhexosaminidase (HEX, E.C. 3.2.1.52) from larvae of the ixodid tick Boophilus microplus was purified to capillary zone electrophoresis homogeneity, and characterized. Enzyme purification was carried out by sequential liquid chromatography on Sephadex G-200, p-aminobenzyl-N-acetyl-beta-D-thioglucosamine affinity, and Mono-Q FPLC columns. Purification was about 1600-fold, with a yield of 10%, as determined with p-nitrophenyl-N-acetylglucosaminide as substrate. The enzyme presented optimum pH 4.7, and optimum temperature 65 degrees C. The molecular weight of non-denatured enzyme was estimated as 127,000 by gel filtration chromatography, and 60,000 in SDS-PAGE. The tick hexosaminidase presented glycosyl residues, as evidenced by binding to Concanavalin-A. Among several p-nitrophenyl glycosides tested as substrate, HEX was active only on p-nitrophenyl-N-acetylglucosaminide and p-nitrophenyl-N-acetylgalactosaminide. The purified enzyme presented immunogenicity in rabbit, and the correspondent antibodies inhibited about 90% of its original, in vitro activity.
Comp Biochem Physiol B Biochem Mol Biol 1999 Jun
PMID:Purification and characterization of beta-N-acetylhexosaminidase from bovine tick Boophilus microplus (Ixodide) larvae. 1042 23


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>