RESUMO
Deuterium-labeled cholesterol-dextran particles (d4-CholDex), prepared by co-precipitation, were internalized by cultured human skin fibroblasts and HEK293 cells. Subcellular particles from d4-CholDex-treated HEK293 cells were fractionated on iodixanol gradients. More than 60% of d4-cholesterol (d4-UC) in the gradient co-fractionated with lysosomal markers and NPC1. This and formation of d4-cholesteryl esters (d4-CE) in the cells suggests that d4-CholDex is lysosomally processed. In accordance with these findings, we observed an increase in lysosomal cholesterol content by fluorescence microscopy in CholDex-loaded cells. Fibroblast cultures including 13 NPC1-deficient, four heterozygous and six control lines were treated with d4-CholDex at final d4-UC concentration of 0.05 mg/ml (127.98 µmol/L) for 3 h and chased for 48 h in medium without d4-CholDex. Concentrations of d4-UC and d4-CE in harvested cells were measured by tandem mass spectrometry (MS/MS). d4-UC/d4-CE ratios were elevated in NP-C lines compared to controls (n = 6, mean = 4.36, range = 1.89-8.91), with the highest ratios in severe NP-C1 phenotypes and the lowest in adolescent/adult type patients. There were overlaps between NP-C1 forms: early infantile (n = 1, mean = 48.6), late infantile (n = 4, mean = 36.3, range = 20.6-54.0), juvenile (n = 5, mean = 24.7, range = 13.4-38.3), adolescent/adult (n = 3, mean = 14.5, range = 11.7-19.8). The ratios in NP-C1 heterozygotes were mildly elevated (n = 4, mean = 16.4, range = 14.9-17.4) and comparable to patients with adolescent/adult NP-C1. The test can be useful in evaluation of suspected NP-C patients with inconclusive results of biomarker or molecular tests. Its advantages include standardized preparation of particles with longer shelf life at 4 °C, quantitative results, and no requirement for radioactive chemicals.
Assuntos
Doença de Niemann-Pick Tipo C , Adolescente , Técnicas de Cultura de Células , Colesterol/metabolismo , Dextranos/metabolismo , Células HEK293 , Humanos , Proteína C1 de Niemann-Pick/genética , Doença de Niemann-Pick Tipo C/diagnóstico , Doença de Niemann-Pick Tipo C/genética , Doença de Niemann-Pick Tipo C/metabolismo , Espectrometria de Massas em TandemRESUMO
Blood group B glycosphingolipids (B-GSLs) are substrates of the lysosomal alpha-galactosidase A (AGAL). Similar to its major substrate-globotriaosylceramide (Gb3Cer)-B-GSLs are not degraded and accumulate in the cells of patients affected by an inherited defect of AGAL activity (Fabry disease-FD).The pancreas is a secretory organ known to have high biosynthesis of blood group GSLs. Herein, we provide a comprehensive overview of the biochemical and structural abnormalities in pancreatic tissue from two male FD patients with blood group B. In both patients, we found major accumulation of a variety of complex B-GSLs carrying predominantly hexa- and hepta-saccharide structures. The subcellular pathology was dominated by deposits containing B-glycoconjugates and autofluorescent ceroid. The contribution of Gb3Cer to the storage was minor. This abnormal storage pattern was specific for the pancreatic acinar epithelial cells. Other pancreatic cell types including those of islets of Langerhans were affected much less or not at all.Altogether, we provide evidence for a key role of B-antigens in the biochemical and morphological pathology of the exocrine pancreas in FD patients with blood group B. We believe that our findings will trigger further studies aimed at assessing the potential pancreatic dysfunction in this disease.
Assuntos
Doença de Fabry/metabolismo , Glicoesfingolipídeos/metabolismo , Pâncreas/metabolismo , Sistema ABO de Grupos Sanguíneos/metabolismo , Células Acinares/metabolismo , Células Acinares/ultraestrutura , Estudos de Casos e Controles , Doença de Fabry/sangue , Doença de Fabry/patologia , Galactose/análise , Galactose/metabolismo , Glicoesfingolipídeos/química , Humanos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/ultraestrutura , Masculino , Pessoa de Meia-Idade , Pâncreas/ultraestruturaRESUMO
Mucopolysaccharidosis type II (MPSII) is a rare X-linked lysosomal storage disorder caused by mutations in the iduronate-2-sulfatase (IDS) gene (IDS, Xq28). MPSII is characterized by skeletal deformities, hearing loss, airway obstruction, hepatosplenomegaly, cardiac valvular disease, and progressive neurological impairment. At the cellular level, IDS deficiency leads to lysosomal storage of glycosaminoglycans (GAGs), dominated by accumulation of dermatan and heparan sulfates. Human induced pluripotent stem cells (iPSC) represent an alternative system that complements the available MPSII murine model. Herein we report on the reprogramming of peripheral white blood cells from male and female MPSII patients into iPSC using a non-integrating protocol based on the Sendai virus vector system. We differentiated the iPSC lines into IDS deficient and GAG accumulating ß-Tubulin III+ neurons, GFAP+ astrocytes, and CNPase+ oligodendrocytes. The lysosomal system in these cells displayed structural abnormalities reminiscent of those previously found in patient tissues and murine IDS deficient neuronal stem cells. Furthermore, quantitative determination of GAGs revealed a moderate increase in GAG levels in IDS deficient neurons and glia. We also tested the effects of recombinant IDS and found that the exogenous enzyme was internalized from the culture media and partially decreased the intracellular GAG levels in iPSC-derived neural cells; however, it failed to completely prevent accumulation of GAGs. In summary, we demonstrate that this human iPSC based model expresses the cellular and biochemical features of MPSII, and thus represents a useful experimental tool for further pathogenesis studies as well as therapy development and testing.
Assuntos
Glicosaminoglicanos/metabolismo , Iduronato Sulfatase/metabolismo , Células-Tronco Pluripotentes Induzidas/enzimologia , Lisossomos/enzimologia , Mucopolissacaridose II/enzimologia , Células-Tronco Neurais/enzimologia , Neurogênese , Neuroglia/enzimologia , Neurônios/enzimologia , Astrócitos/enzimologia , Astrócitos/patologia , Linhagem da Célula , Células Cultivadas , Feminino , Humanos , Iduronato Sulfatase/genética , Células-Tronco Pluripotentes Induzidas/patologia , Lisossomos/patologia , Masculino , Mucopolissacaridose II/genética , Mucopolissacaridose II/patologia , Células-Tronco Neurais/patologia , Neuroglia/patologia , Neurônios/patologia , Células Precursoras de Oligodendrócitos/enzimologia , Células Precursoras de Oligodendrócitos/patologia , Oligodendroglia/enzimologia , Oligodendroglia/patologia , FenótipoRESUMO
Mucolipidosis type IV (MLIV) is a lysosomal storage disease exhibiting progressive intellectual disability, motor impairment, and premature death. There is currently no cure or corrective treatment. The disease results from mutations in the gene encoding mucolipin-1, a transient receptor potential channel believed to play a key role in lysosomal calcium egress. Loss of mucolipin-1 and subsequent defects lead to a host of cellular aberrations, including accumulation of glycosphingolipids (GSLs) in neurons and other cell types, microgliosis and, as reported here, cerebellar Purkinje cell loss. Several studies have demonstrated that N-butyldeoxynojirimycin (NB-DNJ, also known as miglustat), an inhibitor of the enzyme glucosylceramide synthase (GCS), successfully delays the onset of motor deficits, improves longevity, and rescues some of the cerebellar abnormalities (e.g., Purkinje cell death) seen in another lysosomal disease known as Niemann-Pick type C (NPC). Given the similarities in pathology between MLIV and NPC, we examined whether miglustat would be efficacious in ameliorating disease progression in MLIV. Using a full mucolipin-1 knockout mouse (Mcoln1-/-), we found that early miglustat treatment delays the onset and progression of motor deficits, delays cerebellar Purkinje cell loss, and reduces cerebellar microgliosis characteristic of MLIV disease. Quantitative mass spectrometry analyses provided new data on the GSL profiles of murine MLIV brain tissue and showed that miglustat partially restored the wild type profile of white matter enriched lipids. Collectively, our findings indicate that early miglustat treatment delays the progression of clinically relevant pathology in an MLIV mouse model, and therefore supports consideration of miglustat as a therapeutic agent for MLIV disease in humans.
Assuntos
1-Desoxinojirimicina/análogos & derivados , Cerebelo/patologia , Inibidores Enzimáticos/uso terapêutico , Gliose/tratamento farmacológico , Transtornos dos Movimentos/tratamento farmacológico , Mucolipidoses , Células de Purkinje/efeitos dos fármacos , 1-Desoxinojirimicina/uso terapêutico , Animais , Antígenos CD/metabolismo , Contagem de Células , Modelos Animais de Doenças , Comportamento Exploratório/efeitos dos fármacos , Gliose/etiologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transtornos dos Movimentos/etiologia , Mucolipidoses/complicações , Mucolipidoses/genética , Mucolipidoses/patologia , Proteínas do Tecido Nervoso/metabolismo , Desempenho Psicomotor/efeitos dos fármacos , Células de Purkinje/patologia , Retina/patologia , Canais de Potencial de Receptor Transitório/genética , Canais de Potencial de Receptor Transitório/metabolismoRESUMO
Fabry disease is an X-linked lysosomal storage disease due to deficient α-galactosidase A (α-Gal A) activity and the resultant lysosomal accumulation of globotriaosylceramide (Gb3) and related lipids primarily in blood vessels, kidney, heart, and other organs. The renal distribution of stored glycolipid species in the α-Gal A knockout mouse model was compared to that in mice to assess relative distribution and absolute amounts of accumulated sphingolipid isoforms. Twenty isoforms of five sphingolipid groups were visualized by mass spectrometry imaging (MSI), and their distribution was compared with immunohistochemical (IHC) staining of Gb3, the major stored glycosphingolipid in consecutive tissue sections. Quantitative bulk lipid analysis of tissue sections was assessed by electrospray ionization with tandem mass spectrometry (ESI-MS/MS). In contrast to the findings in wild-type mice, all three analytical techniques (MSI, IHC, and ESI-MS/MS) revealed increases in Gb3 isoforms and ceramide dihexosides (composed mostly of galabiosylceramides), respectively. To our knowledge, this is the first report of the distribution of individual molecular species of Gb3 and galabiosylceramides in kidney sections in Fabry disease mouse. In addition, the spatial distribution of ceramides, ceramide monohexosides, and sphingomyelin forms in renal tissue is presented and discussed in the context of their biosynthesis.
Assuntos
Doença de Fabry/metabolismo , Rim/química , Esfingolipídeos/metabolismo , Animais , Modelos Animais de Doenças , Doença de Fabry/enzimologia , Doença de Fabry/genética , Humanos , Imunoquímica , Rim/metabolismo , Espectrometria de Massas , Camundongos , Camundongos Knockout , Esfingolipídeos/química , alfa-Galactosidase/genética , alfa-Galactosidase/metabolismoRESUMO
BACKGROUND: Fabry disease (FD) is an X-linked lysosomal storage disease resulting from pathogenic variants in the GLA gene coding α-galactosidase A (AGAL) and cleaving terminal alpha-linked galactose. Globotriaosylceramide (Gb3) is the predominantly accumulated sphingolipid. Gb3, deacylated-Gb3 (lysoGb3), and methylated-Gb3 (metGb3) have been suggested as FD biomarkers. MATERIALS AND METHODS: We developed a novel LC-MS/MS method for assessing lysoGb3 levels in plasma and Gb3 and metGb3 in urine and tested 62 FD patients, 34 patients with GLA variants of unknown significance (VUS) and 59 healthy controls. AGAL activity in white blood cells (WBCs) and plasma was evaluated in parallel. RESULTS: In males, lysoGb3 concentrations in plasma separated classic and late-onset FD patients from each other and from individuals carrying GLA VUS and healthy controls. Calculating AGAL activity/plasmatic lysoGb3 ratio allowed to correctly categorize all females with classic and majority of patients with late-onset FD phenotypes. Correlation of AGAL activity in WBCS with lipid biomarkers identified threshold activity values under which the biomarkers' concentrations increase. CONCLUSION: We developed a novel simplified LC-MS/MS method for quantitation of plasma lysoGb3. AGAL activity/plasma lysoGb3 ratio was identified as the best predictor for FD. AGAL activity correlated with plasma lysoGb3 and corresponded to individual FD phenotypes.
Assuntos
Doença de Fabry , Esfingolipídeos , Espectrometria de Massas em Tandem , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , alfa-Galactosidase/genética , alfa-Galactosidase/metabolismo , Biomarcadores/sangue , Cromatografia Líquida , Doença de Fabry/sangue , Doença de Fabry/diagnóstico , Doença de Fabry/urina , Glicolipídeos/sangue , Glicolipídeos/urina , Fenótipo , Esfingolipídeos/sangue , Triexosilceramidas/metabolismo , Triexosilceramidas/sangueRESUMO
A series of six full-term placentas and umbilical cords were examined using the in situ detection of globotriaosylceramide (Gb3Cer), GM1 ganglioside (GM1), GM3 ganglioside (GM3), cholesterol and caveolin 1. Immunohistochemical study showed uniform distinct staining of the apical membrane of villous capillary endothelial cells for Gb3Cer, GM1, GM3 and cholesterol. There was also a strong signal for caveolin 1. The immunophenotype suggests the presence of caveola-associated raft microdomains. The immunophenotype was almost completely shared with the extravillous intravascular trophoblast in the basal plate. It was absent in the endothelial cells of umbilical vessels and in the capillaries of somatic structures (heart, lung, skeletal muscle and skin) in neonates as well as in adults, including capillaries of the proliferative endometrium. Results of in situ analyses were confirmed by lipid chromatographic analysis of tissue homogenates and by tandem mass spectrometry. Lysosomal Gb3Cer turnover was followed in three placentas including umbilical cords from Fabry disease (α-galactosidase A deficiency). Lysosomal storage was restricted to vascular smooth muscle cells and to endothelial cells of umbilical vessels. Placental villous capillary endothelial cells displaying a strong non-lysosomal staining for Gb3Cer were free of lysosomal storage.
Assuntos
Capilares/metabolismo , Doença de Fabry/metabolismo , Glicoesfingolipídeos/metabolismo , Placenta/metabolismo , Feminino , Humanos , Gravidez , Espectrometria de Massas em TandemRESUMO
Human acid alpha-glucosidase (GAA, EC 3.2.1.20) is a lysosomal enzyme that belongs to the glycoside hydrolase family 31 (GH31) and catalyses the hydrolysis of alpha-1,4- and alpha-1,6-glucosidic linkages at acid pH. Hereditary deficiency of GAA results in lysosomal glycogen storage disease type II (GSDII, Pompe disease). The aim of this study was to assess GH31 proteins in Caenorhabditis elegans (C. elegans) to identify the ortholog of human GAA. Bioinformatic searches for GAA ortholog in C. elegans genome revealed four acid alpha-glucosidase-related (aagr-1-4) genes. Multiple sequence alignment of AAGRs with other GH31 proteins demonstrated their evolutionary conservation. Phylogenetic analyses suggested clustering of AAGR-1 and -2 with acid-active and AAGR-3 and -4 with neutral-active GH31 enzymes. In order to prove the AAGRs' predicted alpha-glucosidase activity, we performed RNA interference of all four aagr genes. The impact on the alpha-glucosidase activity was evaluated at pH 4.0 (acid) and pH 6.5 (neutral), with or without the inhibitor acarbose. AAGR-1 and -2 expressed acidic alpha-glucosidase activity; on the contrary, AAGR-3 not -4 represented the predominant neutral alpha-glucosidase activity in C. elegans. Similar results were obtained in each of aagr-1 and -4 deletion mutants. Moreover, based on our structural models of AAGRs and these biochemical experiments, we hypothesize that the enzymatic sensitivity of AAGR-2 and human maltase-glucoamylase to the inhibitor acarbose is associated with a tyrosine residue in the GH31 active site, whereas acarbose resistance of AAGR-1 and human GAA is associated with the corresponding tryptophane in the active site. Acid-active AAGR-1 may thus represent the ortholog of human GAA in C. elegans.
Assuntos
Proteínas de Caenorhabditis elegans/genética , alfa-Glucosidases/genética , Acarbose/farmacologia , Animais , Proteínas de Caenorhabditis elegans/antagonistas & inibidores , Proteínas de Caenorhabditis elegans/química , Domínio Catalítico , Biologia Computacional/métodos , Inibidores de Glicosídeo Hidrolases , Humanos , Filogenia , Alinhamento de Sequência , alfa-Glucosidases/químicaRESUMO
The aim of this retrospective study was to determine the prevalence of lysosomal storage disorders (LSDs) in the Czech Republic. The data on cases diagnosed between 1975 and 2008 were collected and analyzed. The overall prevalence of LSDs in the Czech population (12.25 per 100,000) is comparable to that reported for the countries with well-established and advanced diagnostics of LSDs such as the Netherlands (14 per 100,000), Australia (12.9 per 100,000) and Italy (12.1 per 100,000). Relatively higher prevalence of LSDs was reported in the north of Portugal (25 per 100,000). Thirty-four different LSDs were diagnosed in a total of 478 individuals. Gaucher disease was the most frequent LSD with a birth prevalence of 1.13 per 100,000 births. The most frequent LSD groups were lipidoses, mucopolysaccharidoses, and neuronal ceroid lipofuscinoses, with combined prevalences of 5.0, 3.72, and 2.29 per 100,000 live births, respectively. Glycoproteinoses (0.57 per 100,000 live births), glycogenosis type II (0.37), and mucolipidoses (0.31) rarely occur in the Czech population, and a range of other LSDs have not been detected at all over the past three decades. Knowledge of the birth prevalence and carrier frequency of particular disorders is important in genetic counselling for calculation of the risk for the disorder in the other members of affected families. Earlier diagnosis of these disorders will permit timely intervention and may also result in lowering of the number of newborns with LSDs.
Assuntos
Doenças por Armazenamento dos Lisossomos/epidemiologia , Doenças por Armazenamento dos Lisossomos/genética , Austrália/epidemiologia , República Tcheca/epidemiologia , Feminino , Aconselhamento Genético , Predisposição Genética para Doença/epidemiologia , Heterozigoto , Humanos , Recém-Nascido , Itália/epidemiologia , Masculino , Países Baixos/epidemiologia , Portugal/epidemiologia , Prevalência , Estudos RetrospectivosRESUMO
BACKGROUND: Niemann-Pick type C (NP-C) is a rare neurovisceral genetic disorder caused by mutations in the NPC1 or the NPC2 gene. NPC1 is a multipass-transmembrane protein essential for egress of cholesterol from late endosomes/lysosomes. To evaluate impacts of NPC1 mutations, we examined fibroblast cultures from 26 NP-C1 patients with clinical phenotypes ranging from infantile to adult neurologic onset forms. The cells were tested with multiple assays including NPC1 mRNA expression levels and allele expression ratios, assessment of NPC1 promoter haplotypes, NPC1 protein levels, cellular cholesterol staining, localization of the mutant NPC1 proteins to lysosomes, and cholesterol/cholesteryl ester ratios. These results were correlated with phenotypes of the individual patients. RESULTS: Overall we identified 5 variant promoter haplotypes. Three of them showed reporter activity decreased down to 70% of the control sequence. None of the haplotypes were consistently associated with more severe clinical presentation of NP-C. Levels of transcripts carrying null NPC1 alleles were profoundly lower than levels of the missense variants. Low levels of the mutant NPC1 protein were identified in most samples. The protein localised to lysosomes in cultures expressing medium to normal NPC1 levels. Fibroblasts from patients with severe infantile phenotypes had higher cholesterol levels and higher cholesterol/cholesteryl ester ratios. On the contrary, cell lines from patients with juvenile and adolescent/adult phenotypes showed values comparable to controls. CONCLUSION: No single assay fully correlated with the disease severity. However, low residual levels of NPC1 protein and high cholesterol/cholesteryl ester ratios associated with severe disease. The results suggest not only low NPC1 expression due to non-sense mediated decay or low mutant protein stability, but also dysfunction of the stable mutant NPC1 as contributors to the intracellular lipid transport defect.
Assuntos
Proteínas de Transporte , Glicoproteínas de Membrana , Adolescente , Proteínas de Transporte/genética , Fibroblastos/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Mutação/genética , Proteína C1 de Niemann-PickRESUMO
Alterations in GLB1, the gene coding for acid beta-D-galactosidase (beta-Gal), can result in GM1 gangliosidosis (GM1), a neurodegenerative disorder, or in Morquio B disease (MBD), a phenotype with dysostosis multiplex and normal central nervous system (CNS) function. While most MBD patients carry a common allele, c.817TG>CT (p.W273L), only few of the >100 mutations known in GM1 can be related to a certain phenotype. In 25 multiethnic patients with GM1 or MBD, 11 missense mutations were found as well as one novel insertion and a transversion causing aberrant gene products. Except c.602G>A (p.R201H) and two novel alleles, c.592G>T (p.D198Y) and c.1189C>G (p.P397A), all mutants resulted in significantly reduced beta-Gal activities (<10% of normal) upon expression in COS-1 cells. Although c.997T>C (p.Y333H) expressed 3% of normal activity, the mutant protein was localized in the lysosomal-endosomal compartment. A homozygous case presented with late infantile GM1, while a heterozygous, juvenile case carried p.Y333H together with p.R201H. This allele, recently found in homozygous MBD, gives rise to rough endoplasmic reticulum (RER)-located beta-Gal precursors. Thus, unlike classical MBD, the phenotype of heterozygotes carrying p.R201H may rather be determined by poorly active, properly transported products of the counter allele than by the mislocalized p.R201H precursors.
Assuntos
Gangliosidose GM1/genética , Perfilação da Expressão Gênica , Mucopolissacaridose IV/genética , Mutação de Sentido Incorreto , beta-Galactosidase/genética , Animais , Western Blotting , Células COS , Domínio Catalítico , Criança , Pré-Escolar , Chlorocebus aethiops , Eletroforese em Gel de Poliacrilamida , Genótipo , Humanos , Lactente , Fenótipo , beta-Galactosidase/química , beta-Galactosidase/metabolismoRESUMO
Prosaposin deficiency (pSap-d) and saposin B deficiency (SapB-d) are both lipid storage disorders caused by mutations in the PSAP gene that codes for the 65-70 kDa prosaposin protein, which is the precursor for four sphingolipid activator proteins, saposins A-D. We report on two new patients with PSAP gene defects; one, with pSap-d, who had a severe neurovisceral dystrophy and died as a neonate, and the other with SapB-d, who presented with a metachromatic leukodystrophy-like disorder but had normal arylsulfatase activity. Screening for urinary sphingolipids was crucial to the diagnosis of both patients, with electrospray ionization tandem mass spectrometry also providing quantification. The pSap-d patient is the first case with this condition where urinary sphingolipids have been investigated. Multiple sphingolipids were elevated, with globotriaosylceramide showing the greatest increase. Both patients had novel mutations in the PSAP gene. The pSap-d patient was homozygous for a splice-acceptor site mutation two bases upstream of exon 10. This mutation led to a premature stop codon and yielded low levels of transcript. The SapB-d patient was a compound heterozygote with a splice-acceptor site variant exclusively affecting the SapB domain on one allele, and a 2 bp deletion leading to a null, that is, pSap-d mutation, on the other allele. Phenotypically, pSap-d is a relatively uniform disease of the neonate, whereas SapB-d is heterogeneous with a spectrum similar to that in metachromatic leukodystrophy. The possible existence of genotypes and phenotypes intermediate between those of pSap-d and the single saposin deficiencies is speculated.
Assuntos
Leucodistrofia Metacromática/genética , Leucodistrofia Metacromática/metabolismo , Mutação , Saposinas/deficiência , Saposinas/genética , Esfingolipídeos/urina , Encéfalo/anormalidades , Encéfalo/patologia , Criança , Pré-Escolar , Códon sem Sentido , Análise Mutacional de DNA , Heterozigoto , Homozigoto , Humanos , Lactente , Recém-Nascido , Leucodistrofia Metacromática/patologia , Imageamento por Ressonância Magnética , Masculino , Sítios de Splice de RNA/genética , Deleção de Sequência , Pele/patologiaRESUMO
The function and intracellular delivery of enzyme therapeutics for Fabry disease were studied in cultured fibroblasts and in the biopsied tissues of two male patients to show diversity of affected cells in response to treatment. In the mutant fibroblasts cultures, the final cellular level of endocytosed recombinant alpha-galactosidases A (agalsidases, Fabrazyme, and Replagal) exceeded, by several fold, the amount in control fibroblasts and led to efficient direct intra-lysosomal hydrolysis of ((3)H)Gb3Cer. In contrast, in the samples from the heart and some other tissues biopsied after several months of enzyme replacement therapy (ERT) with Fabrazyme, only the endothelial cells were free of storage. Persistent Gb3Cer storage was found in cardiocytes (accompanied by increase of lipopigment), smooth muscle cells, fibroblasts, sweat glands, and skeletal muscle. Immunohistochemistry of cardiocytes demonstrated, for the first time, the presence of a considerable amount of the active enzyme in intimate contact with the storage compartment. Factors responsible for the limited ERT effectiveness are discussed, namely post-mitotic status of storage cells preventing their replacement by enzyme supplied precursors, modification of the lysosomal system by longstanding storage, and possible relative lack of Sap B. These observations support the strategy of early treatment for prevention of lysosomal storage.
Assuntos
Doença de Fabry/terapia , Fibroblastos/enzimologia , Terapia Genética/métodos , alfa-Galactosidase/uso terapêutico , Biópsia , Células Cultivadas , Humanos , Masculino , Microscopia Confocal , Pessoa de Meia-Idade , Miocárdio/enzimologia , alfa-Galactosidase/metabolismoRESUMO
PURPOSE: To confirm and define a molecular basis for a case of mucolipidosis type IV (ML IV) with an extremely atypical phenotype pattern. DESIGN: Observational case report of a patient with ML IV with disease progression restricted to ocular symptoms. METHODS: Complete ophthalmologic and neurologic examination. Ultrastructural examination of white blood cells, skin, conjunctiva, and corneal epithelium. The MCOLN1 gene was sequenced from cDNA and the proportion of splicing variants were assessed by quantitative allele-specific polymerase chain reaction. RESULTS: Absence of any neurological abnormalities. Retinal pathologic features were the main cause of visual disability: low visual acuity and cloudy corneas since 2 years of age, progressive decrease in visual acuity since the age of 9 years. Ultrastructural examination showed storage lysosomes filled with either concentric membranes or lucent precipitate in corneal and conjunctive epithelia and in vascular endothelium. Cultured fibroblasts were free of any autofluorescence. Sequencing of the MCOLN1 gene identified compound heterozygosity for D362Y and A-->T transition leading to the creation of a novel donor splicing site and a 4-bp deletion from exon 13 at the mRNA level. Both normal and pathologic splice forms were detected in skin fibroblasts and leukocytes, with the normal form being more abundant. CONCLUSIONS: The case of this patient with ML IV is unique and is characterized by a curious lack of generalized symptoms. In this patient, the disorder was limited to the eyes and appeared without the usual psychomotor deterioration. The resulting phenotype is the mildest seen to date.
Assuntos
Processamento Alternativo/genética , Doenças da Córnea/genética , Mucolipidoses/genética , Mutação , Degeneração Retiniana/genética , Canais de Cátion TRPM/genética , Criança , Doenças da Túnica Conjuntiva/genética , Doenças da Túnica Conjuntiva/patologia , Doenças da Córnea/patologia , Análise Mutacional de DNA , Eletrorretinografia , Células Epiteliais/ultraestrutura , Epitélio Corneano/ultraestrutura , Feminino , Fibroblastos/ultraestrutura , Humanos , Leucócitos/ultraestrutura , Lisossomos/genética , Lisossomos/ultraestrutura , Mucolipidoses/patologia , Fenótipo , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , Degeneração Retiniana/patologia , Pele/ultraestrutura , Canais de Potencial de Receptor TransitórioRESUMO
We have identified 21 different alpha-galactosidase A gene (GLA) mutations in 22 unrelated Czech and Slovak families with Fabry disease. Eleven of these mutations were novel (point mutations D93N, A135V, D155H, G171R, Q280K, G360S, Q330X, splicing errors c.194ins14, c.801ins36 and deletions c.674_732del59, g.3405_6021del2617). Genotyping of family members for family-specific mutations revealed 55 heterozygotes that manifested clinical symptoms of different severity. To examine the contribution of X-inactivation skewing to disease manifestation in Fabry heterozygotes, we have adopted the Mainz severity scoring scheme and compared the score values with the X-inactivation status in 39 carriers in an age-dependent manner. The age-score trendline of Fabry females who had a predominantly inactivated X-chromosome bearing a wild-type GLA allele (10 of 38 females) was markedly steeper than in the rest of the cohort. One female carrier with an inactivated mutated allele had a low score value when compared to the other heterozygotes of the same age. These data suggest that X-inactivation is indeed a major factor determining the severity of clinical involvement in Fabry heterozygotes. There was a statistically significant difference between the severity score values of heterozygotes with random and non-random X-chromosome inactivation at the 5% level of significance. Further studies will show if the degree of the wildtype allele inactivation will be useful as a predictive marker of severity of phenotype in Fabry heterozygotes. Although the correlation between X-inactivation skewing and presentation of the disease in Fabry heterozygotes has previously been suggested in the literature, this report is among the first attempts to examine this relationship systematically.
Assuntos
Doença de Fabry/genética , Inativação Gênica , Doenças Genéticas Ligadas ao Cromossomo X , alfa-Galactosidase/genética , Adolescente , Adulto , Fatores Etários , Criança , República Tcheca/epidemiologia , Doença de Fabry/epidemiologia , Feminino , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Mutação Puntual , Índice de Gravidade de Doença , Eslováquia/epidemiologiaRESUMO
BACKGROUND: Human alpha-galactosidase A (alpha-GAL) and alpha-N-acetylgalactosaminidase (alpha-NAGA) are presumed to share a common ancestor. Deficiencies of these enzymes cause two well-characterized human lysosomal storage disorders (LSD)--Fabry (alpha-GAL deficiency) and Schindler (alpha-NAGA deficiency) diseases. Caenorhabditis elegans was previously shown to be a relevant model organism for several late endosomal/lysosomal membrane proteins associated with LSDs. The aim of this study was to identify and characterize C. elegans orthologs to both human lysosomal luminal proteins alpha-GAL and alpha-NAGA. RESULTS: BlastP searches for orthologs of human alpha-GAL and alpha-NAGA revealed a single C. elegans gene (R07B7.11) with homology to both human genes (alpha-galactosidase and alpha-N-acetylgalactosaminidase)--gana-1. We cloned and sequenced the complete gana-1 cDNA and elucidated the gene organization.Phylogenetic analyses and homology modeling of GANA-1 based on the 3D structure of chicken alpha-NAGA, rice alpha-GAL and human alpha-GAL suggest a close evolutionary relationship of GANA-1 to both human alpha-GAL and alpha-NAGA. Both alpha-GAL and alpha-NAGA enzymatic activities were detected in C. elegans mixed culture homogenates. However, alpha-GAL activity on an artificial substrate was completely inhibited by the alpha-NAGA inhibitor, N-acetyl-D-galactosamine.A GANA-1::GFP fusion protein expressed from a transgene, containing the complete gana-1 coding region and 3 kb of its hypothetical promoter, was not detectable under the standard laboratory conditions. The GFP signal was observed solely in a vesicular compartment of coelomocytes of the animals treated with Concanamycin A (CON A) or NH4Cl, agents that increase the pH of the cellular acidic compartment. Immunofluorescence detection of the fusion protein using polyclonal anti-GFP antibody showed a broader and coarsely granular cytoplasmic expression pattern in body wall muscle cells, intestinal cells, and a vesicular compartment of coelomocytes.Inhibition of gana-1 by RNA interference resulted in a decrease of both alpha-GAL and alpha-NAGA activities measured in mixed stage culture homogenates but did not cause any obvious phenotype. CONCLUSIONS: GANA-1 is a single C. elegans ortholog of both human alpha-GAL and alpha-NAGA proteins. Phylogenetic, homology modeling, biochemical and GFP expression analyses support the hypothesis that GANA-1 has dual enzymatic activity and is localized in an acidic cellular compartment.
Assuntos
Proteínas de Caenorhabditis elegans/genética , alfa-Galactosidase/genética , alfa-N-Acetilgalactosaminidase/genética , Animais , Sequência de Bases , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/metabolismo , Clonagem Molecular , Evolução Molecular , Humanos , Lisossomos , Dados de Sequência Molecular , Filogenia , Proteínas , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Homologia Estrutural de Proteína , alfa-Galactosidase/metabolismo , alfa-N-Acetilgalactosaminidase/química , alfa-N-Acetilgalactosaminidase/metabolismoRESUMO
BACKGROUND: Prediagnostic steps in suspected metachromatic leukodystrophy (MLD) rely on clinical chemical methods other than enzyme assays. We report a new diagnostic method which evaluates changes in the spectrum of molecular types of sulfatides (3-O-sulfogalactosyl ceramides) in MLD urine. METHODS: The procedure allows isolation of urinary sulfatides by solid-phase extraction on DEAE-cellulose membranes, transportation of a dry membrane followed by elution and tandem mass spectrometry (MS/MS) analysis in the clinical laboratory. Major sulfatide isoforms are normalized to the least variable component of the spectrum, which is the indigenous C18:0 isoform. This procedure does not require the use of specific internal standards and minimizes errors caused by sample preparation and measurement. RESULTS: Urinary sulfatides were analyzed in a set of 21 samples from patients affected by sulfatidosis. The combined abundance of the five most elevated isoforms, C22:0, C22:0-OH, C24:0, C24:1-OH, and C24:0-OH sulfatides, was found to give the greatest distinction between MLD-affected patients and a control group. CONCLUSIONS: The method avoids transportation of liquid urine samples and generates stable membrane-bound sulfatide samples that can be stored at ambient temperature. MS/MS sulfatide profiling targeted on the most MLD-representative isoforms is simple with robust results and is suitable for screening.
Assuntos
Leucodistrofia Metacromática/urina , Manejo de Espécimes/normas , Sulfoglicoesfingolipídeos/urina , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , DEAE-Celulose , Dessecação , Feminino , Humanos , Lactente , Leucodistrofia Metacromática/diagnóstico , Masculino , Membranas Artificiais , Pessoa de Meia-Idade , Padrões de Referência , Extração em Fase Sólida , Espectrometria de Massas em TandemRESUMO
BACKGROUND: Fabry disease (FD) is a genetic disorder characterized by accumulation of trihexosylceramide in lysosomes of various tissues leading to multiorgan manifestations, including progressive renal disease. Previous screening studies have shown that a non-neglectable proportion of haemodialysis(HD) patients have unsuspected FD. An extensive FD screening study, the largest to date, has been conducted in HD patients in Czech Republic. We aimed to uncover previously undiagnosed FD patients, to enable them to benefit from cause-specific therapeutic intervention with enzyme replacement therapy (ERT). METHODS: Large-scale screening was executed using a convenient automated enzymatic (alpha-galactosidose A, alpha-Gal A) dried blood spot on filter paper fluorescence method. RESULTS: In total, 3370 (45.1% males, 54.9% females) out of 4058 HD patients (83%) in Czech Republic participated in this blood spot screening (BSS) study. Abnormal low fluorescence readings were obtained in 117 patients (3.5%). Subsequent determination of plasma alpha-Gal A activity identified four males and three females with deficient plasma enzyme activity. Determination of alpha-Gal A activity in peripheral blood leucocytes and confirmatory molecular analysis resulted in four newly diagnosed Fabry males and one female. Subsequent family screening identified 10 family members with genotypically proven FD. Based on these screening results, ERT could be offered to five male FD patients. CONCLUSIONS: BSS represents a promising screening tool that has proven to be convenient and effective in uncovering unrecognized FD patients among the chronic HD population in Czech Republic.
Assuntos
Doença de Fabry/sangue , Doença de Fabry/diagnóstico , Diálise Renal/métodos , Adulto , Idoso , República Tcheca , Terapia Enzimática , Doença de Fabry/terapia , Feminino , Humanos , Lisossomos/metabolismo , Masculino , Pessoa de Meia-Idade , Linhagem , Conformação Proteica , Espectrometria de Fluorescência , alfa-Galactosidase/químicaRESUMO
We present two sisters with a severe form of Fabry disease, who both carry the same mutation in the alpha-galactosidase A (alpha-gal A) gene (Q330X). Each of the sisters developed renal failure in the third decade of life; the older sibling underwent renal transplantation at 40 years of age. The severe phenotype of the siblings correlates with results of the X-inactivation study: examination of methylation status in human androgene receptor (HUMARA) gene suggests preferential inactivation of the wild-type allele in both patients. Patients' parents had no symptoms of Fabry disease and were tested negative for the mutation Q330X in DNA isolated from peripheral leukocytes, mouth wash cells, and urinary sediment cells. Genotype analysis using DXS7424 marker showed paternal origin of the mutation. The father's sperm was then tested for presence of the mutation to examine the possibility of the germline mosaicism. Both mutant and wild-type alleles were found in DNA isolated from father's sperm. The apparent explanation of these findings is germline mosaicism due to mutation event during the embryonic development of sperm producing cells (spermatogonia). This is the first case of germline mosaicism in Fabry disease reported in the literature.
Assuntos
Doença de Fabry/genética , Mutação em Linhagem Germinativa/genética , Mosaicismo , alfa-Galactosidase/genética , Adulto , Mecanismo Genético de Compensação de Dose , Doença de Fabry/enzimologia , Saúde da Família , Feminino , Humanos , Masculino , Linhagem , Receptores Androgênicos/genética , alfa-Galactosidase/metabolismoRESUMO
Metachromatic leukodystrophy (MLD) is an inherited demyelinating disorder caused by the deficiency of arylsulphatase A (ASA). This defect leads to an accumulation of galactosylceramide I(3)-sulphates (sulphatides) in lysosomes of different tissues. We report on mutations found in a group of nine patients from the Czech and Slovak Republics (former Czechoslovakia). Their diagnosis was confirmed by determination of the activity of arylsulphatase A in leukocytes and by abnormal urinary excretion of sulphatides. All alleles of the patients were identified and eight different mutations were found. They include four novel missense mutations in one infantile (D29N), one juvenile (C294Y), and three adult (C156R, G293S) patients. Four mutations were previously described sequence alterations (459 + 1G > A, G309S, I179S, and P426L). Polymorphisms characteristic for the ASA pseudodeficiency allele were not found in the patients. Substitutions of D29N, C294Y, and G293S in arylsulphatase A caused a severe reduction of enzyme activity in transient expression studies. In contrast, the C156R substitution reduces arylsulphatase A only to 50% of wild type ASA activity. Since no other mutations were found in this patient, the contribution of this mutation to the development of disease remains unclear.