Cloning and characterization of cDNA encoding canine alpha-L-iduronidase. mRNA deficiency in mucopolysaccharidosis I dog.
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alpha-L-Iduronidase is a lysosomal enzyme, the deficiency of which causes mucopolysaccharidosis I (MPS I); a canine MPS I colony has been bred to test therapeutic intervention. The enzyme was purified to apparent homogeneity from canine testis and found to consist of two electrophoretically separable proteins that had common internal peptides but differed at their amino termini. A 57-base oligonucleotide, corresponding to the most probable codons of the longest peptide, was used to screen a canine testis cDNA library. Three cDNAs were isolated, two of which lacked the 5'-end whereas the third was full-length except for a small internal deletion. The composite sequence encodes an open reading frame of 655 amino acids that includes all sequenced peptides. The amino terminus of the larger protein, glutamic acid 26, is at the predicted signal peptide cleavage site, whereas the amino terminus of the smaller protein is leucine 106. There are six potential N-glycosylation sites and a non-canonical polyadenylation signal, CTTAAA. A search of GenBank showed that the amino acid sequence of alpha-L-iduronidase has similarity to that of a bacterial beta-xylosidase. A full-length cDNA corresponding to the composite sequence was constructed (pcIdu) and inserted into the pSVL expression vector (pSVcIdu). Two days after Cos-1 cells were transfected with pSVcIdu, their intracellular and secreted level of alpha-L-iduronidase activity has increased 8- and 22-fold, respectively, over the endogenous activity. Fibroblasts of MPS I dogs, which have no alpha-L-iduronidase activity, lacked the normal alpha-L-iduronidase mRNA of 2.2 kilobases and contained instead a trace amount of a 2.8-kilobase species. Isolation and characterization of an expressible alpha-L-iduronidase cDNA represents the first step toward mutation analysis and replacement therapy. (+info)
Articular manifestations of Scheie's syndrome.
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A patient with the clinical and biochemical features of Scheie's syndrome is reported. Radiological investigation has shown severe progressive juxta-articular cystic lesions, which have not, to our knowledge, previously been described in Scheie's syndrome. (+info)
Atypical microbial infections of digestive tract may contribute to diarrhea in mucopolysaccharidosis patients: a MPS I case study.
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BACKGROUND: Mucopolysaccharidoses are heritable, metabolic diseases caused by deficiency in an activity of one of specific lysosomal enzymes involved in degradation of mucoplysaccharides (glycosaminoglycans). Among many medical problems of patients with mucopolysaccharidoses, there are frequent episodes of diarrhea of unknown etiology. CASE PRESENTATION: A girl, diagnosed enzymatically for mucopolysaccharidosis type I (deficiency of alpha-L-iduronidase) at the age of 3 years and 9 months, was investigated until the age of 5 years and 4 months. Frequent loose stools and episodes of diarrhea, often accompanied by vomiting, were encountered. Detailed microbiological analyses were performed and atypical microbial infections (most often enetropathogenic Escherichia coli, but also other species, like Pseudomonas aeruginosa or Staphylococcus aureus, as well as adenoviruses) of the digestive tract were found in most severe diarrhea episodes. Often, isolations of pathogenic bacterial strains from stools of the investigated patient suffering from diarrhea were not obvious during the first screening, and only detailed microbiological studies, including re-isolation of colonies, gave the results of isolation of particular pathogenic strains (especially in the case of enetropathogenic E. coli). CONCLUSION: We conclude that atypical microbial infections of digestive tract may contribute significantly to diarrhea in mucopolysaccaridosis patients. Since isolated strains were not typical and their isolation was often possible only after detailed investigation (not during a standard screening), such atypical microbial infections of digestive tract of mucopolysaccharidosis patients could be usually overlooked to date. Importantly, these atypical infections could be effectively treated with antimicrobial agents. (+info)
Functional abnormalities of heparan sulfate in mucopolysaccharidosis-I are associated with defective biologic activity of FGF-2 on human multipotent progenitor cells.
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In mucopolysaccharidosis-I (MPS-I), alpha-L-iduronidase deficiency leads to progressive heparan sulfate (HS) and dermatan sulfate (DS) glycosaminoglycan (GAG) accumulation. The functional consequences of these accumulated molecules are unknown. HS critically influences tissue morphogenesis by binding to and modulating the activity of several cytokines (eg, fibroblast growth factors [FGFs]) involved in developmental patterning. We recently isolated a multipotent progenitor cell from postnatal human bone marrow, which differentiates into cells of all 3 embryonic lineages. The availability of multipotent progenitor cells from healthy volunteers and patients with MPS-I (Hurler syndrome) provides a unique opportunity to directly examine the functional effects of abnormal HS on cytokine-mediated stem-cell proliferation and survival. We demonstrate here that abnormally sulfated HS in Hurler multipotent progenitor cells perturb critical FGF-2-FGFR1-HS interactions, resulting in defective FGF-2-induced proliferation and survival of Hurler multipotent progenitor cells. Both the mitogenic and survival-promoting activities of FGF-2 were restored by substitution of Hurler HS by normal HS. This perturbation of critical HS-cytokine receptor interactions may represent a mechanism by which accumulated HS contributes to the developmental pathophysiology of Hurler syndrome. Similar mechanisms may operate in the pathogenesis of other diseases where structurally abnormal GAGs accumulate. (+info)
Cardiac manifestations in the mouse model of mucopolysaccharidosis I.
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Mucopolysaccharidosis I (MPS I, alpha-l-iduronidase deficiency disease) is a heritable lysosomal storage disorder involving multiple organs, including the heart. Malfunction of the heart is also a major manifestation in the mouse model of MPS I, progressing in severity from 6 to 10 months (of a 1 year life span). In comparisons of MPS I with wild-type mice, the heart was found enlarged, with thickened septal and posterior walls, primarily because of infiltration of the muscle by storage-laden cells. Heart valves were enlarged and misshapen, and contained large numbers of highly vacuolated interstitial cells. The thickened aortic wall contained vacuolated smooth muscle cells and interrupted elastic fibers. Hemodynamic measurements and echocardiography revealed reduced left ventricular function as well as mitral and aortic regurgitation. But despite these abnormalities, free-roaming MPS I mice implanted with radio telemetry devices showed surprisingly normal heart rate and blood pressure, though their electrocardiograms were abnormal. An incidental finding of the telemetry studies was a disturbed circadian rhythm in the MPS I mice. Restoration of enzyme activity in the heart of one mouse, by transplantation of retrovirally modified bone marrow, resulted in normalization of left ventricular function as well as loss of storage vacuoles in myocytes and endothelial cells, though not in valvular interstitial cells. This study demonstrates the usefulness of the mouse model for in-depth studies of the cardiovascular component of MPS I. (+info)
Hepatic storage of glycosaminoglycans in feline and canine models of mucopolysaccharidoses I, VI, and VII.
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Livers from normal cats and dogs, cats with mucopolysaccharidoses (MPS) I and VI, and dogs with MPS VII were analyzed biochemically and morphometrically to determine the lysosomal storage of glycosaminoglycans (GAG) in these animal models of human genetic disease. Analyses were performed on liver samples from seven normal cats ranging in age from 13 weeks to 15 months; six MPS I-affected cats ranging in age from 10 weeks to 26 months; four MPS VI-affected cats ranging in age from 9 months to 32 months; four normal dogs ranging in age from 1 month to 47 months; and three MPS VII-affected dogs, 5 days, 11 days, and 14 months of age. All of the animals were from the breeding colony at the University of Pennsylvania School of Veterinary Medicine and were maintained in accordance with national standards for the care and use of laboratory animals. Each GAG subclass was quantitated, and total GAG concentration was determined. Liver from cats with MPS I had the highest total GAG concentration (5.7 times that of the control), followed by liver from dogs with MPS VII (1.8 times) and cats with MPS VI (1.5 times). These data were very closely correlated (R2 = 0.982) with the results of the morphometric analyses of hepatocyte and Kupffer cell vacuolation associated with lysosomal storage and support the validity of both methods. This is particularly important for the quantification of total and individual GAG concentrations in tissue preparations. The values obtained should prove useful in future assessments of therapeutic regimes, such as enzyme replacement, bone marrow transplantation, and gene therapy, for these genetic diseases. (+info)
Common antigenicity for two glycosidases.
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Enzyme replacement therapy (ERT) has proven to be an effective therapy for some lysosomal storage disorder (LSD) patients. A potential complication during ERT is the generation of an immune response against the replacement protein. We have investigated the antigenicity of two distantly related glycosidases, alpha-glucosidase (Pompe disease or glycogen storage disease type II, GSD II), and alpha-L-iduronidase (Hurler syndrome, mucopolysaccharidosis type I, MPS I). The linear sequence epitope reactivity of affinity purified polyclonal antibodies to recombinant human alpha-glucosidase and alpha-L-iduronidase was defined, to both glycosidases. The polyclonal antibodies exhibited some cross-reactive epitopes on the two proteins. Moreover, a monoclonal antibody to the active site of alpha-glucosidase showed cross-reactivity with a catalytic structural element of alpha-L-iduronidase. In a previous study, in MPS I patients who developed an immune response to ERT, this same site on alpha-L-iduronidase was highly antigenic and the last to tolerise following repeated enzyme infusions. We conclude that glycosidases can exhibit cross-reactive epitopes, and infer that this may relate to common structural elements associated with their active sites. (+info)
Hurler syndrome with a tuft of hair.
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A 2-year-old girl presented with coarse, thick hairy skin all over the body, a tuft of hair in the parietal region, coarse facial features and a prominent forehead with a large tongue, hepatosplenomegaly and skeletal deformities. Mucopolysaccharides excretion spot test of the urine was positive; and an assay for glycosaminoglycans in the urine was also high, which confirmed the clinical diagnosis of Hurler syndrome. We present this rare case to discuss the possibility of the association of mental retardation with a tuft of hair in this syndrome. (+info)