Loading of cell cultures with cholesterol-dextran particles as a new functional test for Niemann-Pick type C disease.

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.

Neuroinflammation, mitochondrial defects and neurodegeneration in mucopolysaccharidosis III type C mouse model.

Severe progressive neurological paediatric disease mucopolysaccharidosis III type C is caused by mutations in the HGSNAT gene leading to deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase involved in the lysosomal catabolism of heparan sulphate. To understand the pathophysiology of the disease we generated a mouse model of mucopolysaccharidosis III type C by germline inactivation of the Hgsnat gene. At 6-8 months mice showed hyperactivity, and reduced anxiety. Cognitive memory decline was detected at 10 months and at 12-13 months mice showed signs of unbalanced hesitant walk and urinary retention. Lysosomal accumulation of heparan sulphate was observed in hepatocytes, splenic sinus endothelium, cerebral microglia, liver Kupffer cells, fibroblasts and pericytes. Starting from 5 months, brain neurons showed enlarged, structurally abnormal mitochondria, impaired mitochondrial energy metabolism, and storage of densely packed autofluorescent material, gangliosides, lysozyme, phosphorylated tau, and amyloid-ß. Taken together, our data demonstrate for the first time that deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase causes lysosomal accumulation of heparan sulphate in microglial cells followed by their activation and cytokine release. They also show mitochondrial dysfunction in the neurons and neuronal loss explaining why mucopolysaccharidosis III type C manifests primarily as a neurodegenerative disease.

Identification of novel informative loci for DNA-based X-inactivation analysis.

The HUMARA assay, the most common method for evaluation of X-inactivation skewing in blood cells, has been reported to be usable in only about 80% of females, emphasizing the need for alternative methods for testing of HUMARA-uninformative individuals. We conducted an in silico search for potentially polymorphic tri-to-hexanucleotide repeats in the proximity of CpG islands located in 5' regions of X-chromosome genes to design five candidate assays (numbered I, II, III, IV, and V) combining methylation-specific restriction digest with PCR amplification in a manner similar to the HUMARA assay. The results obtained by these assays in 100 healthy females were compared to X-inactivation skewing measured by the AR-MSP method which is based on methylation-specific PCR amplification of the first exon of the AR gene. On the basis of statistical evidence, three of the novel assays (II, IV, and V), which were informative in 18%, 61%, and 55% of females in the cohort, respectively, may be used as alternatives or conjointly with the HUMARA assay to improve its reliability. The three new assays were combined with the HUMARA assay into a novel X-inactivation test leading to the increase of informative females in the cohort from 67% to 96%.

Glucocerebrosidase gene has an alternative upstream promoter, which has features and expression characteristic of housekeeping genes.

Database searches have shown that a part of glucocerebrosidase (GBA) transcripts may originate at an alternative upstream promoter (P2) located 2.6 kb upstream of the known (P1) GBA promoter. The putative alternative transcripts contained one or two extra exons (exon -2 or exons -2, -1, respectively), but the first ATG codon and predicted amino-acid sequence are the same as in the transcript from P1. Luciferase assays confirmed promoter activity of both sites in HepG2 cells: the P1 construct exhibited the highest activity of luciferase (17.82±1.10 relative luciferase units), while the P2 construct reached 3.01±0.43 relative luciferase units. Serial 5' deletions of P2 led to changes in reporter activity, the most prominent decreases were observed in deletion constructs carrying bases -353 to -658, and -353 to -920 (numbered as in NM_001005750.1), respectively. This suggests that the P2 core promoter is contained within the region of -920bp to -1311bp. Three P2 transcription initiation sites were found by 5' RACE at positions 347, 380, and 413bp upstream of the +1 ATG. The expression stability of transcripts from P2, P1 was studied in 20 human tissues and was higher than that of GAPDH and ACTB, which are commonly used as reference housekeeping genes. The P2 contains an unmethylated CpG island, multiple Sp-1 consensus binding sites and, unlike P1, does not contain a TATA box, features all common to the majority of housekeeping gene promoters. We have examined DNA samples from a phenotypically diverse group of twenty Ashkenazi Jewish Gaucher patients homozygous for the common mild mutation N370S. Both P1 and P2, as well as exons -2 and -1, did not contain any sequence variations, with the exception of the known polymorphism rs10908459 found on one allele. The phenotypical differences in the patients were thus not explained by nucleotide variations in both promoters.

Disruption of OTC promoter-enhancer interaction in a patient with symptoms of ornithine carbamoyltransferase deficiency.

In a female patient with signs of ornithine carbamoyltransferase deficiency (OTCD), the only variation found was a heterozygous single nucleotide substitution c.-366A>G. Determination of transcription start sites of human OTC 95, 119 and 169 bp upstream of the initiation codon located the variation upstream of the 5'-untranslated region. We predicted the human promoter and enhancer elements from homology with rat and mouse, performed function analysis of both regulatory regions and assessed the impact of the promoter variation in functional studies using dual luciferase reporter assay. Our data indicate that: (i) Full transcriptional activity of human OTC promoter depends on an upstream enhancer, as do the rodent promoters. (ii) The promoter variation c.-366A>G does not affect the function of the promoter alone but it disrupts the interaction of the promoter with the enhancer. (iii) The promoter-enhancer interaction contributes to tissue specific expression of OTC in the liver. We conclude that mutations in the regulatory regions of OTC can lead to OTCD and should be included in genetic testing.

Force majeure: therapeutic measures in response to restricted supply of imiglucerase (Cerezyme) for patients with Gaucher disease.

Gaucher disease is the first lysosomal disorder for which clinically effective enzyme replacement therapy has been introduced. Lifelong treatment with imiglucerase, the recombinant glucocerebrosidase manufactured by the Genzyme Corporation (MA, USA), is administered intravenously - usually at biweekly intervals. An acute shortage of imiglucerase (to 20% of prior global supply) has occurred as a result of viral contamination of the production facility; production was halted, and a full supply of imiglucerase is not anticipated until January 2010. An urgent meeting of physicians, researchers, and patients was convened through the agency of the European Working Group for Gaucher Disease; this was instigated by patients internationally represented by the European Gaucher Alliance. Here we present a position statement based on the findings of the group, with key recommendations about identification and monitoring of at-risk patients threatened by the abrupt withdrawal of treatment, the equitable distribution of residual imiglucerase - and access to alternative treatments including those that have completed phase III clinical trials but have not yet been licensed.

Bioinformatic and biochemical studies point to AAGR-1 as the ortholog of human acid alpha-glucosidase in Caenorhabditis elegans.

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.

Transcript, protein, metabolite and cellular studies in skin fibroblasts demonstrate variable pathogenic impacts of NPC1 mutations.

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.

Sanfilippo syndrome type C: mutation spectrum in the heparan sulfate acetyl-CoA: alpha-glucosaminide N-acetyltransferase (HGSNAT) gene.

Mucopolysaccharidosis (MPS) type IIIC or Sanfilippo syndrome type C is a rare autosomal recessive disorder caused by the deficiency of the lysosomal membrane enzyme, heparan sulfate acetyl-CoA (AcCoA): alpha-glucosaminide N-acetyltransferase (HGSNAT; EC 2.3.1.78), which catalyzes transmembrane acetylation of the terminal glucosamine residues of heparan sulfate prior to their hydrolysis by alpha-N-acetylglucosaminidase. Lysosomal storage of undegraded heparan sulfate in the cells of affected patients leads to neuronal death, causing neurodegeneration and severely impaired development accompanied by mild visceral and skeletal abnormalities, including mild dwarfism, coarse facies, and joint stiffness. To date, 50 HGSNAT mutations have been identified in MPS IIIC patients: 40 were previously published and 10 novel mutations are reported here. The mutations span the entire structure of the gene and include 13 splice-site mutations, 11 insertions and deletions, 8 nonsense mutations, and 18 missense mutations (http://chromium.liacs.nl/LOVD2/home.php?select_db=HGSNAT). In addition, four polymorphisms result in amino acid changes that do not affect activity of the enzyme. In this work we discuss the spectrum of MPS IIIC mutations, their clinical presentation and distribution within the patient population, and speculate how the mutations may affect the structure and function of HGSNAT.

Prosaposin deficiency and saposin B deficiency (activator-deficient metachromatic leukodystrophy): report on two patients detected by analysis of urinary sphingolipids and carrying novel PSAP gene mutations.

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.

Mucopolysaccharidosis type I in 21 Czech and Slovak patients: mutation analysis suggests a functional importance of C-terminus of the IDUA protein.

Mucopolysaccharidosis type I (MPS I) is an autosomal recessive lysosomal storage disorder that is caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). Of the 21 Czech and Slovak patients who have been diagnosed with MPS I in the last 30 years, 16 have a severe clinical presentation (Hurler syndrome), 2 less severe manifestations (Scheie syndrome), and 3 an intermediate severity (Hurler/Scheie phenotype). Mutation analysis was performed in 20 MPS I patients and 39 mutant alleles were identified. There was a high prevalence of the null mutations p.W402X (12 alleles) and p.Q70X (7 alleles) in this cohort. Four of the 13 different mutations were novel: p.V620F (3 alleles), p.W626X (1 allele), c.1727 + 2T > G (1 allele) and c.1918_1927del (2 alleles). The pathogenicity of the novel mutations was verified by transient expression studies in Chinese hamster ovary cells. Seven haplotypes were observed in the patient alleles using 13 intragenic polymorphisms. One of the two haplotypes associated with the mutation p.Q70X was not found in any of the controls. Haplotype analysis showed, that mutations p.Q70X, p.V620F, and p.D315Y probably have more than one ancestor. Missense mutations localized predominantly in the hydrophobic core of the enzyme are associated with the severe phenotype, whereas missense mutations localized to the surface of the enzyme are usually associated with the attenuated phenotypes. Mutations in the 130 C-terminal amino acids lead to clinical manifestations, which indicates a functional importance of the C-terminus of the IDUA protein.

Variable X-chromosome inactivation and enlargement of pericentral glutamine synthetase zones in the liver of heterozygous females with OTC deficiency.

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder that causes recurrent and life-threatening episodes of hyperammonemia. The clinical picture in heterozygous females is highly diverse and derives from the genotype and the degree of inactivation of the mutated X chromosome in hepatocytes. Here, we describe molecular genetic, biochemical, and histopathological findings in the livers explanted from two female patients with late-onset OTC deficiency. Analysis of X-inactivation ratios by DNA methylation-based assays showed remarkable intra-organ variation ranging from 46:54 to 82:18 (average 70:30, n = 37), in favor of the active X chromosome carrying the mutation c.583G>C (p.G195R), in the first patient and from 75:25 to 90:10 (average 82:18, n = 20) in favor of the active X chromosome carrying the splicing mutation c.663+1G>A in the second patient. The X-inactivation ratios in liver samples correlated highly with the proportions of OTC-positive hepatocytes calculated from high-resolution image analyses of the immunohistochemically detected OTC in frozen sections that was performed on total area > 5 cm2. X-inactivation ratios in blood in both female patients corresponded to the lower limit of the liver values. Our data indicate that the proportion of about 20-30% of hepatocytes expressing the functional OTC protein is not sufficient to maintain metabolic stability. X-inactivation ratios assessed in liver biopsies taken from heterozygous females with X-linked disorders should not be considered representative of the whole liver.

Consensus clinical management guidelines for Niemann-Pick disease type C.

Niemann-Pick Type C (NPC) is a progressive and life limiting autosomal recessive disorder caused by mutations in either the NPC1 or NPC2 gene. Mutations in these genes are associated with abnormal endosomal-lysosomal trafficking, resulting in the accumulation of multiple tissue specific lipids in the lysosomes. The clinical spectrum of NPC disease ranges from a neonatal rapidly progressive fatal disorder to an adult-onset chronic neurodegenerative disease. The age of onset of the first (beyond 3 months of life) neurological symptom may predict the severity of the disease and determines life expectancy.NPC has an estimated incidence of ~ 1: 100,000 and the rarity of the disease translate into misdiagnosis, delayed diagnosis and barriers to good care. For these reasons, we have developed clinical guidelines that define standard of care for NPC patients, foster shared care arrangements between expert centres and family physicians, and empower patients. The information contained in these guidelines was obtained through a systematic review of the literature and the experiences of the authors in their care of patients with NPC. We adopted the Appraisal of Guidelines for Research & Evaluation (AGREE II) system as method of choice for the guideline development process. We made a series of conclusive statements and scored them according to level of evidence, strengths of recommendations and expert opinions. These guidelines can inform care providers, care funders, patients and their carers of best practice of care for patients with NPC. In addition, these guidelines have identified gaps in the knowledge that must be filled by future research. It is anticipated that the implementation of these guidelines will lead to a step change in the quality of care for patients with NPC irrespective of their geographical location.

Effect of miglustat on bone disease in adults with type 1 Gaucher disease: a pooled analysis of three multinational, open-label studies.

BACKGROUND: Bone manifestations are a source of disability among patients with Gaucher disease (GD) and a focus of disease management. The effect of enzyme replacement therapy (ERT) on GD bone disease can be limited and may take up to 8 years to become manifest. Miglustat, a glucosylceramide synthase inhibitor, may have a positive influence on GD bone disease. OBJECTIVES: The aim of this analysis was to evaluate the effects of miglustat on bone manifestations and bone mineral density (BMD) in patients with type 1 GD. METHODS: This was a pooled analysis of data collected prospectively over an observation period of 2 years from patients who participated in 3 multinational, open-label clinical trials evaluating the efficacy and tolerability of miglustat 100 mg TID (the currently approved therapeutic dose). Bone manifestations were assessed qualitatively and in relation to treatment and spleen status. The effects of miglustat on BMD were assessed by dual-energy x-ray absorptiometry at the lumbar spine and/or femoral neck. Bone response was defined as a positive change in BMD, based on the change in BMD Z-score from baseline to months 6, 12, and 24. Changes in BMD were also analyzed according to spleen status and baseline severity of osteopenia. RESULTS: The analysis involved 72 patients, including 41 (57%) who had received previous ERT and 20 (28%) who had undergone splenectomy. Patients' mean (SD) age was 41.2 (13.1) years. The most frequent bone-related manifestations at study entry were osteoporosis (43/63 [68%] patients) and bone pain (41/65 [63%] patients). At 2 years, 54/65 (83%) patients reported no bone pain. The reductions in bone pain were comparable among all subgroups, including high-risk patients (ie, splenectomized). No new cases of bone crisis, avascular necrosis, or pathologic fractures were reported. BMD Z-scores were improved from baseline at both the lumbar spine and femoral neck at each time point (months 6, 12, and 24) (P < 0.001). As early as 6 months after the initiation of miglustat monotherapy, significant increases from baseline in the BMD Z-score were observed at both the lumbar spine (mean, 0.15; P = 0.022) and femoral neck (0.23; P < 0.001); the increases remained significant at 12 months (0.19 [P = 0.012] and 0.21 [P = 0.017], respectively) and 24 months (0.21 [P = 0.015] and 0.18 [P = 0.039]). Significant increases in BMD Z-scores were observed at the femoral neck in splenectomized patients (P < 0.001) and at both sites in osteoporotic patients (lumbar spine: P < 0.001; femoral neck: P = 0.006). CONCLUSION: This pooled analysis of 3 open-label studies of miglustat 100 mg TID suggests that miglustat monotherapy may reduce the incidence of bone pain and improve BMD in patients with type 1 GD, including those with a history of splenectomy and/or osteoporosis.

Relationship between X-inactivation and clinical involvement in Fabry heterozygotes. Eleven novel mutations in the alpha-galactosidase A gene in the Czech and Slovak population.

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.

HGSNAT has a TATA-less promoter with multiple starts of transcription.

Acetyl-CoA:α-glucosaminide N-acetyltransferase (N-acetyltransferase) is a lysosomal membrane enzyme that catalyzes a key step in the lysosomal degradation of heparan sulfate. Its deficiency causes Sanfilippo syndrome type IIIC (Mucopolysaccharidosis type IIIC, MPS IIIC). Here we characterize the promoter region of HGSNAT, the gene encoding N-acetyltransferase, which is located in the pericentromeric region of chromosome 8. We show that HGSNAT transcription is driven by a TATA-less promoter whose key elements are contained within the 1054bp region upstream of exon 1. About 400 bases of the region's 3'-prime end overlap with an unmethylated CpG island. Reduced reporter activities from promoter serial deletion constructs suggested strong regulatory elements at positions -101 to -20bp and -1073 to -716bp of the downstream initiation codon (DS-ATG). Targeted mutagenesis of the first Specificity protein 1-A (Sp1-A) of the six in silico-predicted Sp1 sites in the region flanking the major transcription start sites (TSSs, +50/-101) led to a 55% decrease of reporter activity, while inactivation of each of Sp1-B and Sp1-C resulted in its almost two-fold increase. The binding of Sp1 to the region was confirmed by chromatin immunoprecipitation (ChIP). Overall, this confirms that Sp1 is important for regulation of the HGSNAT promoter. Promoter fragments in antisense orientation (constructs pGL4 -20/-1305 and pGL4 +50/-1305) led to reporter activities of about 50% of the pGL4 -1305/-20 activity, implying divergent initiation of transcription at the promoter. We identified two main TSSs at positions +1 and -15 from DS-ATG using Rapid amplification of cDNA ends (5'RACE). Transcripts initiating at the TSSs thus contain only DS-ATG. Five patients from our MPS IIIC cohort (n=23) carried the rs4523300 promoter variant and one the rs149596192 promoter variant. Both variants lowered the expression of the reporter down to 68% and 59%, respectively. However, white blood cell (WBC) N-acetyltransferase activities in individuals carrying the variants did not significantly differ from homozygotes for the wild-type alleles, suggesting only a partial impact of transcriptional regulation on N-acetyltransferase activities in vivo.

Characterization of gana-1, a Caenorhabditis elegans gene encoding a single ortholog of vertebrate alpha-galactosidase and alpha-N-acetylgalactosaminidase.

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.

Transient expression of wild-type and mutant glucocerebrosidases in hybrid vaccinia expression system.

Gaucher disease, the most prevalent lysosomal storage disease, is characterised by a significant phenotypic variation caused by more than 150 mutations. In order to verify pathogenicity of mutations found in the Czech Gaucher population, the vaccinia expression system was used. The wild-type human beta-glucocerebrosidase cDNA and cDNAs carrying the mutations 72delC, 1326insT, 1263del55, S196P, N370S, L444P, G202E, D409H, T369M, L444P+V460V, and D409H+T369M were expressed in Gaucher fibroblast cell line (L444P/S107L), BSC40, and HeLa G cells. The enzymatic activity and immunological reactivity were analysed. Only beta-glucocerebrosidase-deficient fibroblasts were suitable for expression using plasmid transfection. The expressed beta-glucosidase activity of mutant glucocerebrosidases was in good correlation with the presumed severity of the mutations.

Indel in the FIC1/ATP8B1 gene-a novel rare type of mutation associated with benign recurrent intrahepatic cholestasis.

Benign recurrent intrahepatic cholestasis (BRIC) is a rare inherited liver disease characterized by recurrent attacks of severe cholestasis with no progression to end stage liver disease. Patients have jaundice, however, serum gamma-glutamyltransferase and cholesterol levels remain within the normal range during the attacks. Three mutations in the familial intrahepatic cholestasis 1 (ATP8B1) gene encoding a P-type ATPase have been reported so far in patients with the autosomal recessive form of BRIC. A novel rare type insertion-deletion mutation, also called indel, was found in exon 24 of ATP8B1 in our patient together with a known missense mutation 1982T>C in exon 17. The mechanism of the indel formation is proposed and impact of the indel mutation on the function of ATP8B1 protein is discussed.

Observational, retrospective study of a large cohort of patients with Niemann-Pick disease type C in the Czech Republic: a surprisingly stable diagnostic rate spanning almost 40 years.

BACKGROUND: Niemann-Pick disease type C (NPC) is a rare, fatal neurovisceral disorder with autosomal recessive inheritance, and featuring striking clinical variability dependent on the age at onset of neurological symptoms. We report data from a large cohort of 56 Czech patients with NPC diagnosed over a period of 37 years. METHODS: An observational, retrospective analysis of historic and current clinical and laboratory information was performed among all NPC patients originating from the area of the contemporary Czech Republic and diagnosed between 1975 and 2012. All patients with ≥1 positive diagnostic test and relevant clinical information were included. Data on diagnostic methods (histopathological and/or ultrastructural; biochemical; genetic), clinical status and general information on treatment were collated. Data were examined in accordance with international guidelines for the management of NPC. RESULTS: Between 1975 and 1985 diagnoses were based exclusively on specific histopathological findings, often at autopsy. Bone marrow smear (BMS) analyses have proved to be a very specific indicator for NPC and have become an important part of our diagnostic algorithm. Filipin staining and cholesterol esterification assays became the definitive diagnostic tests after 1985 and were applied in 24 of our patients. Since 2005, more and more patients have been assessed using NPC1/NPC2 gene sequencing. Twelve patients were diagnosed with neonatal/early-infantile onset NPC, 13 with the late-infantile onset form, 20 with the juvenile onset form, and nine with the adolescent/adult onset form. Two diagnosed patients remained neurologically asymptomatic at study completion. Nineteen patients were siblings. Causal NPC1 mutations were determined in 38 patients; two identical NPC2 mutations were identified in one patient. In total, 30 different mutations were identified, 14 of which have been confirmed as novel. The frequency of individual mutated NPC1 alleles in our cohort differs compared with previous published data: the most frequent mutant NPC1 allele was p.R1186H (n = 13), followed by p.P1007A (n = 8), p.S954L (n = 8) and p.I1061T (n = 4). CONCLUSIONS: These data demonstrate the evolution of the diagnostic process in NPC over the last four decades. We estimate the contemporary birth prevalence of NPC in the Czech Republic at 0.93 per 100,000.