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The Biochemical Journal Aug 1991The specificity of human liver lysosomal alpha-mannosidase (EC 3.2.1.24) towards a series of oligosaccharide substrates derived from high-mannose, complex and hybrid...
The specificity of human liver lysosomal alpha-mannosidase (EC 3.2.1.24) towards a series of oligosaccharide substrates derived from high-mannose, complex and hybrid asparagine-linked glycans and from the storage products in alpha-mannosidosis was investigated. The enzyme hydrolyses all alpha(1-2)-, alpha(1-3)- and alpha(1-6)-mannosidic linkages in these glycans without a requirement for added Zn2+, albeit at different rates. A major finding of this study is that all the substrates are hydrolysed by non-random pathways. These pathways were established by determining the structures of intermediates in the digestion mixtures by a combination of h.p.t.l.c. and h.p.l.c. before and after acetolysis. The catabolic pathway for a particular substrate appears to be determined by its structure, raising the possibility that degradation occurs by an uninterrupted sequence of steps within one active site. The structures of the digestion intermediates are compared with the published structures of the storage products in mannosidosis and of intact asparagine-linked glycans. Most but not all of the digestion intermediates derived from high-mannose glycans have structures found in intact asparagine-linked glycans of human glycoproteins or among the storage products in the urine of patients with mannosidosis. However, the relative abundances of these structures suggests that the catabolic pathway is not the same as the processing pathway. In contrast, the intermediates formed from the digestion of oligosaccharides derived from hybrid and complex N-glycans are completely different from any processing intermediates and also from the oligosaccharides of composition Man2-4GlcNAc that account for 80-90% of the storage products in alpha-mannosidosis. It is postulated that the structures of these major storage products arise from the action of an exo/endo-alpha(1-6)-mannosidase on the partially catabolized oligomannosides that accumulate in the absence of the main lysosomal alpha-mannosidase.
Topics: Chromatography, High Pressure Liquid; Humans; Lysosomes; Mannosidases; Oligosaccharides; Polysaccharides; Structure-Activity Relationship; Substrate Specificity; alpha-Mannosidosis
PubMed: 1872811
DOI: 10.1042/bj2770743 -
The Journal of Biological Chemistry Nov 1990Human beta-mannosidosis urine was fractionated by gel permeation chromatography on Bio-Gel P-2 and by high performance liquid chromatography on Partisil 10 SAX. Besides...
Human beta-mannosidosis urine was fractionated by gel permeation chromatography on Bio-Gel P-2 and by high performance liquid chromatography on Partisil 10 SAX. Besides the disaccharide Man beta 1-4GlcNAc as the major component, a sialic acid-containing compound was detected in an amount of 10% compared to that of Man beta 1-4GlcNAc. Structural characterization of the oligosaccharide and of its reduced analogue by sugar composition analysis, methylation analysis, gas-liquid chromatography-mass spectrometry, and 500-MHz 1H NMR spectroscopy gave conclusive evidence for a novel urinary constituent: NeuAc alpha 2-6Man beta 1-4GlcNAc. This linear trisaccharide can be considered as the result of an alpha 2-6-sialylation of the major accumulating compound, Man beta 1-4GlcNAc. The hitherto unknown linkage between sialic acid and mannose was shown to be susceptible to sialidase digestion.
Topics: Carbohydrate Sequence; Carbohydrates; Chromatography, Gel; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Gas Chromatography-Mass Spectrometry; Humans; Magnetic Resonance Spectroscopy; Male; Mannose; Mannosidases; Methylation; Molecular Sequence Data; N-Acetylneuraminic Acid; Sialic Acids; Trisaccharides; beta-Mannosidase
PubMed: 2246252
DOI: No ID Found -
European Journal of Biochemistry Apr 1990In vitro incubation of the oligomannosyl oligosaccharides Man9GlcNAc and Man5GlcNAc with isolated disrupted lysosomes yields different oligosaccharide isomers resulting...
In vitro incubation of the oligomannosyl oligosaccharides Man9GlcNAc and Man5GlcNAc with isolated disrupted lysosomes yields different oligosaccharide isomers resulting from mannosidase hydrolysis. These isomers were isolated by HPLC and characterized by 1H-NMR spectroscopy. The first steps of the degradation involve an (alpha 1-2)mannosidase activity and lead to the formation of one Man8GlcNAc, one Man7GlcNAc, two Man6GlcNAc and two Man5GlcNAc isomers. These reactions do not require Zn2+ as activator. On the other hand, the following steps, which lead to the formation of Man3GlcNAc and Man2GlcNAc, are Zn2(+)-dependent. This process is characterized by the preferential action of an (alpha 1-3)mannosidase activity, and the formation of Man(alpha 1-6)Man(alpha 1-6)Man(beta 1-4)GlcNAc and Man(alpha 1-6)Man(beta 1-4)GlcNAc. Therefore, the digestion of Man9GlcNAc inside the lysosome appears to follow a very specific pathway, since only nine intermediate compounds can be identified instead of the 38 possible isomers. Our results are consistent both with the existence of several specific enzymes for alpha 1-2, alpha 1-3 and alpha 1-6 linkages, and with the presence of a unique enzyme whose specificity would be dependent either on Zn2+ or on the spatial conformation of the glycan. Nevertheless, previous work on the structural analysis of oligosaccharides excreted in the urine of patients suffering from mannosidosis, demonstrates the absence of the core alpha 1-6-linked mannosyl residue in the major storage product derived from oligomannosyl oligosaccharides. This observation indicates the presence of a specific (alpha 1-6)mannosidase form, unaffected in mannosidosis.
Topics: Animals; Carbohydrate Conformation; Carbohydrate Sequence; Cell Fractionation; Chromatography, High Pressure Liquid; Female; Kinetics; Liver; Lysosomes; Mannosidases; Molecular Sequence Data; Oligosaccharides; Rats; Rats, Inbred Strains; Substrate Specificity
PubMed: 2338081
DOI: 10.1111/j.1432-1033.1990.tb15498.x -
Canadian Journal of Veterinary Research... Jan 1990Interest in using caprine beta-D-mannosidosis as a model to evaluate bone marrow transplantation in the treatment of human lysosomal storage disorders provided the...
Interest in using caprine beta-D-mannosidosis as a model to evaluate bone marrow transplantation in the treatment of human lysosomal storage disorders provided the stimulus for characterization of beta-D-mannosidase in selected goat tissues and induction of hemopoietic chimerism in the goat. Total beta-D-mannosidase activity was measured with the use of 4-methylumbelliferyl beta-D-mannopyranoside as substrate. Residual activity in mutant liver was 52% of control but no activity was detectable in mutant kidney or brain tissue. Normal adult goat liver contained two forms of beta-D-mannosidase, a nonlysosomal form (52%) with a broad pH range for optimum activity (4.5-8.0) and a lysosomal form (48%) with a pH optimum of 5.5. Residual enzyme in mutant liver consisted entirely of the nonlysosomal form. Normal adult thyroid, kidney and brain contained two major lysosomal isoenzymes with pIs 5.5 and 5.9 and traces of a minor isoenzyme with pI 5.0. Normal liver contained three isoenzymes with similar pIs; however, an isoenzyme with pI 5.0 predominated. In 60-day fetal liver lysosomal isoenzymes predominated and only trace amounts of nonlysosomal isoenzyme were detectable. Total hepatic beta-D-mannosidase activity increased towards adult levels during the last 90 days of gestation as a result of increasing nonlysosomal isoenzyme activity. Intraperitoneal injection of fetal liver cells into 60-day goat fetuses resulted in sustained hemopoietic chimerism in surviving kids without evidence of graft-versus-host-disease. These results suggest that transplantation of normal fetal liver cells into preimmunocompetent goat fetuses affected with beta-D-mannosidosis is feasible and may provide an alternative strategy for evaluation of postnatal bone marrow transplantation in the treatment of human lysosomal storage disorders.
Topics: Animals; Animals, Newborn; Brain; Disease Models, Animal; Fetus; Goat Diseases; Goats; Kidney; Liver; Mannosidases; Thyroid Gland; alpha-Mannosidosis; beta-Mannosidase
PubMed: 2306674
DOI: No ID Found -
Journal of Veterinary Internal Medicine 1988Three Domestic Long-haired cats from a litter of five afflicted with alpha-mannosidosis (alpha-mannosidosis) were studied clinically and pathologically. Many of these...
Three Domestic Long-haired cats from a litter of five afflicted with alpha-mannosidosis (alpha-mannosidosis) were studied clinically and pathologically. Many of these findings contrasted with those made previously in kittens with deficiency of alpha-mannosidase. In these cats, the clinical signs were generally milder, more slowly progressive, and did not include the prominent skeletal deformities, ocular abnormalities, or hepatomegaly that were reported in prior studies of Persian and Domestic Short-haired kittens. While the Domestic Long-haired cats were spared the central nervous system (CNS) myelin deficiency, which was severe in the Persian but mild in the Domestic Short-haired cats, the extensive loss of Purkinje cells in their cerebellar cortices was without precedent. Additionally, ultrastructural study of the neuronal cytosomes showed a diversity not recorded in the earlier cases. The observed phenotypic heterogeneity was sufficient enough to consider separating feline alpha-mannosidosis into severe, acute and milder, chronic forms in a manner analogous to the Type I and Type II distinctions made in infants and juveniles.
Topics: Animals; Brain; Brain Diseases; Cat Diseases; Cats; Female; Male; Mannosidases; Microscopy, Electron; Neurons; alpha-Mannosidase; alpha-Mannosidosis
PubMed: 3230555
DOI: 10.1111/j.1939-1676.1988.tb00311.x -
American Journal of Human Genetics Feb 1988Four examples of Israeli communities or large families in which high consanguinity is common are presented, with two different lysosomal storage disorders within each...
Four examples of Israeli communities or large families in which high consanguinity is common are presented, with two different lysosomal storage disorders within each community. In each of the four cases the stored substances share common chemical structure, despite the different lysosomal hydrolases involved in each disease. A similar phenomenon is known among the Ashkenazi Jews, in whom four of the most frequent hereditary disorders are lysosomal storage disorders, which are characterized by storage of sphingolipid derivatives. Similar findings are reported in the literature in other communities. We suggest that this phenomenon indicates a selection in favor of lysosomal storage disorders of similar nature in certain populations. The selection forces leading to this phenomenon have not been identified yet, and it has not yet been determined whether these forces are the same in the different communities presented here.
Topics: Consanguinity; Female; Gangliosidoses; Humans; Infant; Israel; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Male; Metabolism, Inborn Errors; Mucopolysaccharidoses; Pedigree; Selection, Genetic; alpha-Mannosidosis
PubMed: 3124612
DOI: No ID Found -
The Journal of Neuroscience : the... Feb 1988Ectopic dendrite growth and new synapse formation are known to occur on select kinds of neurons in a wide variety of neuronal storage diseases. As these changes in...
Ectopic dendrite growth and new synapse formation are known to occur on select kinds of neurons in a wide variety of neuronal storage diseases. As these changes in connectivity occur just proximal to the axonal initial segment, it has been hypothesized that they underlie the generation of abnormal neuronal function in these diseases. We have studied certain aspects of this phenomenon through the use of a plant-derived indolizadine alkaloid, swainsonine, which specifically inhibits the lysosomal hydrolase, alpha-mannosidase. These studies fully document the close morphological similarity between swainsonine-induced and inherited feline alpha-mannosidosis. This includes the presence of clear and floccule-filled storage vacuoles, as seen with routine EM, and axon hillock neurite growth on select cell types, as seen with Golgi staining. The latter was found only on cortical pyramidal neurons and multipolar cells of amygdala, and these same cell types are known to be involved in ectopic neuritogenesis in other storage diseases. Combined Golgi-electron-microscopic studies demonstrated the presence of normal-appearing synapses on these aberrant neuritic processes and also unusual, membranous inclusions specifically within the neurite-bearing pyramidal cells. The latter may be indicative of unique metabolic changes in these neurons and is consistent with the hypothesis that storage of gangliosides or other glycolipids underlies the recapitulation of dendritic growth features in these diseases. Experimental manipulation of the disease process using the swainsonine model indicated that induction of cortical pyramidal neuron neurite growth could be influenced by both age of onset and intensity of intraneuronal storage. Although Golgi studies clearly demonstrated neuritic sprouting in animals with disease onset as late as at 1 year, cortical pyramidal cells of older, adult animals appeared to undergo significant storage without a similar induction of neurite growth. These studies support the view that induced neuritogenesis in neuronal storage disease is associated with changes in metabolism, specifically within the neurite-bearing cells, that this change possibly involves gangliosides, and that the neuritogenic response may be limited to pre-adult stages of brain maturation.
Topics: Alkaloids; Animals; Cats; Dendrites; Golgi Apparatus; Microscopy, Electron; Swainsonine; Synapses; alpha-Mannosidosis
PubMed: 3123615
DOI: 10.1523/JNEUROSCI.08-02-00445.1988 -
The Biochemical Journal Nov 1987The kidneys of man, sheep, cattle and pig were all found to contain 1-aspartamido-beta-acetylglucosamine amidohydrolase activity. However, among these, only human kidney...
The kidneys of man, sheep, cattle and pig were all found to contain 1-aspartamido-beta-acetylglucosamine amidohydrolase activity. However, among these, only human kidney was found to contain endo-beta-N-acetylglucosaminidase activity. The absence of this enzyme in the kidneys of sheep and cattle explains why the oligosaccharides accumulated in, and excreted by, sheep and cattle afflicted with disorders of glycoprotein catabolism (i.e. alpha-mannosidosis and beta-mannosidosis) contain two N-acetylglucosamine residues at the reducing terminus instead of one, as is the case for human patients afflicted with similar disorders.
Topics: Acetylglucosaminidase; Animals; Asialoglycoproteins; Cattle; Chromatography, Gel; Chromatography, Thin Layer; Fibrinogen; Hexosaminidases; Hydrolysis; Kidney; Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; Ovalbumin; Sheep; Species Specificity; Swine
PubMed: 3124807
DOI: 10.1042/bj2480145 -
Archives of Disease in Childhood Oct 1987Bone marrow transplantation was performed in a patient with alpha-mannosidosis. To our knowledge this is the first time such treatment has been attempted. The patient...
Bone marrow transplantation was performed in a patient with alpha-mannosidosis. To our knowledge this is the first time such treatment has been attempted. The patient died 18 weeks after successful grafting and specimens of tissues were obtained at necropsy. Alpha-mannosidase activity in spleen and liver was just below normal (spleen 102 mumol/g/hour, control 113-330; liver 29 mumol/g/hour, control 30-131). Splenic alpha-mannosidase activity was indistinguishable from the control enzyme with respect to the Michaelis constant, heat stability, and inhibition by cobalt ions, as was 86% of the liver enzyme. In brain tissue alpha-mannosidase activity was 7% of controls, and less than one third had the properties of the normal enzyme. Oligosaccharides were present only in small amounts in liver and spleen, whereas they were greatly increased in brain tissue. Electron microscopic pictures of liver and spleen tissue showed normal morphology, but brain tissue showed definite vacuolation. These findings suggest that transplantation reversed the somatic changes of alpha-mannosidosis but did not affect lysosomal storage within brain tissue. It is concluded that marrow transplantation may not be a suitable treatment for alpha-mannosidosis.
Topics: Bone Marrow Transplantation; Brain; Child; Chromatography, Thin Layer; Humans; Liver; Male; Mannosidases; Oligosaccharides; Spleen; alpha-Mannosidase; alpha-Mannosidosis
PubMed: 3314721
DOI: 10.1136/adc.62.10.1044 -
The Journal of Biological Chemistry May 1987Swainsonine is a potent inhibitor of lysosomal alpha-D-mannosidase, causes the production of hybrid glycoproteins, and is reported to produce a phenocopy of hereditary...
Substrate specificities of rat kidney lysosomal and cytosolic alpha-D-mannosidases and effects of swainsonine suggest a role of the cytosolic enzyme in glycoprotein catabolism.
Swainsonine is a potent inhibitor of lysosomal alpha-D-mannosidase, causes the production of hybrid glycoproteins, and is reported to produce a phenocopy of hereditary alpha-mannosidosis. We now report that the effects of swainsonine administration in the rat are different in two respects from those found in other animals thus far studied. Swainsonine caused the accumulation of oligosaccharide in kidney and urine but not in liver or brain. The accumulated oligosaccharides were mainly Man(alpha 1-3)[Man(alpha 1-6)]Man(beta 1-4)GlcNAc, Man(alpha 1-3)[Man(alpha 1-6)[Man(alpha 1-3)]Man(beta 1-4) GlcNAc, and Man(alpha 1-3)[Man(alpha 1-6)]Man(alpha 1-6)[Man(alpha 1-3)]Man(beta 1-4)GlcNAc. Analogous branched Man4 and Man5 structures are found in pig and sheep tissues, but they are N, N'-diacetylchitobiose derivatives. The substrate specificities of rat kidney lysosomal and cytosolic alpha-D-mannosidases were investigated because in one type of hereditary alpha-mannosidosis, that occurring in man, the major storage products are linear rather than branched oligosaccharides. The lysosomal enzyme showed much greater activity toward linear oligosaccharides than toward the branched oligosaccharides induced in the kidney by swainsonine. On the other hand, cytosolic alpha-D-mannosidase preferred the branched oligosaccharides, a result suggesting that this mannosidase might be inhibitable by swainsonine and that the enzyme might play a normal role in glycoprotein catabolism. Swainsonine was indeed found to inhibit this enzyme at relatively high concentrations (I50 at 100 microM swainsonine), and concentrations of this magnitude were in fact found in the cytosol of kidney of swainsonine-fed rats. The kidney cytosolic alpha-D-mannosidase levels were reduced in these rats and, more important, the accumulated oligosaccharides were present mainly in the cytosol rather than in lysosomes. These results point to possible involvement of cytosolic alpha-D-mannosidase in glycoprotein degradation in the rat.
Topics: Alkaloids; Animals; Cytosol; Glycoproteins; Isoenzymes; Kidney; Kinetics; Lysosomes; Male; Mannosidases; Oligosaccharides; Rats; Rats, Inbred Strains; Substrate Specificity; Swainsonine; alpha-Mannosidase
PubMed: 3106356
DOI: No ID Found