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Uribe-Carretero E, Rey V, Fuentes JM, Tamargo-Gómez I. Lysosomal Dysfunction: Connecting the Dots in the Landscape of Human Diseases. BIOLOGY 2024; 13:34. [PMID: 38248465 PMCID: PMC10813815 DOI: 10.3390/biology13010034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/22/2023] [Accepted: 01/02/2024] [Indexed: 01/23/2024]
Abstract
Lysosomes are the main organelles responsible for the degradation of macromolecules in eukaryotic cells. Beyond their fundamental role in degradation, lysosomes are involved in different physiological processes such as autophagy, nutrient sensing, and intracellular signaling. In some circumstances, lysosomal abnormalities underlie several human pathologies with different etiologies known as known as lysosomal storage disorders (LSDs). These disorders can result from deficiencies in primary lysosomal enzymes, dysfunction of lysosomal enzyme activators, alterations in modifiers that impact lysosomal function, or changes in membrane-associated proteins, among other factors. The clinical phenotype observed in affected patients hinges on the type and location of the accumulating substrate, influenced by genetic mutations and residual enzyme activity. In this context, the scientific community is dedicated to exploring potential therapeutic approaches, striving not only to extend lifespan but also to enhance the overall quality of life for individuals afflicted with LSDs. This review provides insights into lysosomal dysfunction from a molecular perspective, particularly in the context of human diseases, and highlights recent advancements and breakthroughs in this field.
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Affiliation(s)
- Elisabet Uribe-Carretero
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Enfermería y Terapia Ocupacional, Universidad de Extremadura, 10003 Caceres, Spain; (E.U.-C.)
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativa, Instituto de Salud Carlos III (CIBER-CIBERNED-ISCIII), 28029 Madrid, Spain
- Instituto Universitario de Investigación Biosanitaria de Extremadura (INUBE), 10003 Caceres, Spain
| | - Verónica Rey
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain
| | - Jose Manuel Fuentes
- Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Enfermería y Terapia Ocupacional, Universidad de Extremadura, 10003 Caceres, Spain; (E.U.-C.)
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativa, Instituto de Salud Carlos III (CIBER-CIBERNED-ISCIII), 28029 Madrid, Spain
- Instituto Universitario de Investigación Biosanitaria de Extremadura (INUBE), 10003 Caceres, Spain
| | - Isaac Tamargo-Gómez
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain
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Decreased Levels of Chaperones in Mucopolysaccharidoses and Their Elevation as a Putative Auxiliary Therapeutic Approach. Pharmaceutics 2023; 15:pharmaceutics15020704. [PMID: 36840025 PMCID: PMC9967431 DOI: 10.3390/pharmaceutics15020704] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/15/2023] [Accepted: 02/18/2023] [Indexed: 02/22/2023] Open
Abstract
Mucopolysaccharidoses (MPS) are rare genetic disorders belonging to the lysosomal storage diseases. They are caused by mutations in genes encoding lysosomal enzymes responsible for degrading glycosaminoglycans (GAGs). As a result, GAGs accumulate in lysosomes, leading to impairment of cells, organs and, consequently, the entire body. Many of the therapies proposed thus far require the participation of chaperone proteins, regardless of whether they are therapies in common use (enzyme replacement therapy) or remain in the experimental phase (gene therapy, STOP-codon-readthrough therapy). Chaperones, which include heat shock proteins, are responsible for the correct folding of other proteins to the most energetically favorable conformation. Without their appropriate levels and activities, the correct folding of the lysosomal enzyme, whether supplied from outside or synthesized in the cell, would be impossible. However, the baseline level of nonspecific chaperone proteins in MPS has never been studied. Therefore, the purpose of this work was to determine the basal levels of nonspecific chaperone proteins of the Hsp family in MPS cells and to study the effect of normalizing GAG concentrations on these levels. Results of experiments with fibroblasts taken from patients with MPS types I, II, IIIA, IIIB, IIIC, IID, IVA, IVB, VI, VII, and IX, as well as from the brains of MPS I mice (Idua-/-), indicated significantly reduced levels of the two chaperones, Hsp70 and Hsp40. Interestingly, the reduction in GAG levels in the aforementioned cells did not lead to normalization of the levels of these chaperones but caused only a slight increase in the levels of Hsp40. An additional transcriptomic analysis of MPS cells indicated that the expression of other genes involved in protein folding processes and the cell response to endoplasmic reticulum stress, resulting from the appearance of abnormally folded proteins, was also modulated. To summarize, reduced levels of chaperones may be an additional cause of the low activity or inactivity of lysosomal enzymes in MPS. Moreover, this may point to causes of treatment failure where the correct structure of the enzyme supplied or synthesized in the cell is crucial to lower GAG levels.
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Okur I, Ezgu F, Giugliani R, Muschol N, Koehn A, Amartino H, Harmatz P, de Castro Lopez MJ, Couce ML, Lin SP, Batzios S, Cleary M, Solano M, Peters H, Lee J, Nestrasil I, Shaywitz AJ, Maricich SM, Kuca B, Kovalchin J, Zanelli E. Longitudinal Natural History of Pediatric Subjects Affected with Mucopolysaccharidosis IIIB. J Pediatr 2022; 249:50-58.e2. [PMID: 35709957 DOI: 10.1016/j.jpeds.2022.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 05/31/2022] [Accepted: 06/08/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To characterize the longitudinal natural history of disease progression in pediatric subjects affected with mucopolysaccharidosis (MPS) IIIB. STUDY DESIGN Sixty-five children with a confirmed diagnosis of MPS IIIB were enrolled into 1 of 2 natural history studies and followed for up to 4 years. Cognitive and adaptive behavior functions were analyzed in all subjects, and volumetric magnetic resonance imaging analysis of liver, spleen, and brain, as well as levels of heparan sulfate (HS) and heparan sulfate nonreducing ends (HS-NRE), were measured in a subset of subjects. RESULTS The majority of subjects with MPS IIIB achieved an apex on both cognition and adaptive behavior age equivalent scales between age 3 and 6 years. Development quotients for both cognition and adaptive behavior follow a linear trajectory by which subjects reach a nadir with a score <25 for an age equivalent of 24 months by age 8 years on average and by 13.5 years at the latest. All tested subjects (n = 22) had HS and HS-NRE levels above the normal range in cerebrospinal fluid and plasma, along with signs of hepatomegaly. Subjects lost an average of 26 mL of brain volume (-2.7%) over 48 weeks, owing entirely to a loss of cortical gray matter (32 mL; -6.5%). CONCLUSIONS MPS IIIB exists along a continuum based on cognitive decline and cortical gray matter atrophy. Although a few individuals with MPS IIIB have an attenuated phenotype, the majority follow predicted trajectories for both cognition and adaptive behavior. TRIAL REGISTRATION ClinicalTrials.gov identifiers NCT02493998, NCT03227042, and NCT02754076.
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Affiliation(s)
- Ilyas Okur
- Department of Pediatric Metabolism, Gazi University Faculty of Medicine, Ankara, Turkey; Department of Genetics, Gazi University Faculty of Medicine, Ankara, Turkey
| | - Fatih Ezgu
- Department of Pediatric Metabolism, Gazi University Faculty of Medicine, Ankara, Turkey; Department of Genetics, Gazi University Faculty of Medicine, Ankara, Turkey
| | - Roberto Giugliani
- Medical Genetics Service and DR Brasil, HCPA, Department of Genetics, UFRGS, DASA, and INAGEMP, Porto Alegre, Brazil
| | - Nicole Muschol
- International Center for Lysosomal Disorders, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anja Koehn
- International Center for Lysosomal Disorders, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Paul Harmatz
- UCSF Benioff Children's Hospital Oakland, Oakland, CA
| | - Maria J de Castro Lopez
- Hospital Clínico Universitario de Santiago, University of Santiago de Compostela, IDIS, CIBERER, MetabERN, A Coruña, Spain
| | - Maria Luz Couce
- Hospital Clínico Universitario de Santiago, University of Santiago de Compostela, IDIS, CIBERER, MetabERN, A Coruña, Spain
| | | | | | | | | | | | - Joy Lee
- Royal Children's Hospital, Melbourne, Australia
| | - Igor Nestrasil
- Division of Clinical Behavioral Neuroscience and Masonic Institute for the Developing Brain, Department of Pediatrics, University of Minnesota, Minneapolis, MN
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Highly diverse phenotypes of mucopolysaccharidosis type IIIB sibling patients: effects of an additional mutation in the AUTS2 gene. J Appl Genet 2022; 63:535-542. [PMID: 35525889 DOI: 10.1007/s13353-022-00702-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 10/18/2022]
Abstract
Mucopolysaccharidosis type IIIB (MPS IIIB or Sanfilippo syndrome type B) is an inherited metabolic disease caused by mutations in the NAGLU gene, encoding α-N-acetylglucosaminidase. Accumulation of undegraded heparan sulfate (one of glycosaminoglycans) arises from deficiency in this enzyme and leads to severe symptoms, especially related to dysfunctions of the central nervous system. Here, we describe a case of two siblings with highly diverse phenotypes, despite carrying the same mutations (c.1189 T > G/c.1211G > A (p.Phe397Val/p.Trp404Ter)) and similar residual activities of α-N-acetylglucosaminidase; the younger patient reveals more severe phenotype; thus, these differences cannot be explained by the age and progression of the disease. Surprisingly, the whole exome sequencing analysis indicated the presence of an additional mutation in one allele of the AUTS2 gene (c.157G > A (p.Ala53Thr)) in the younger patient but not in the older one. Since mutations in this gene are usually dominant and cause delayed development and intellectual disability, it is likely that the observed differences between the MPS IIIB siblings are due to the potentially pathogenic AUTS2 variant, present in one of them. This case confirms also that simultaneous occurrence of two ultra-rare diseases in one patient is actual, despite a low probability of such a combination. Moreover, it is worth noting that apart from the genotype-phenotype correlation and the importance of the residual activity of the deficient enzyme, efficiency of glycosaminoglycan synthesis and global secondary changes in expression of hundreds of genes may considerably modulate the course and severity of MPS, especially Sanfilippo disease.
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Montenegro YHA, Baldo G, Giugliani R, Poswar FDO, Sobrinho RPDO, Steiner CE. Schizophreniform presentation and abrupt neurologic decline in a patient with late-onset mucopolysaccharidosis type IIIB. Psychiatr Genet 2021; 31:199-204. [PMID: 34347683 DOI: 10.1097/ypg.0000000000000294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Due to their low frequency and some atypical presentations, inborn errors of metabolism are frequently misdiagnosed or underdiagnosed, which hinders the correct management of these patients. To illustrate that, here we present a patient that, at early school age, had learning disabilities compared to her classmates, especially for writing. She completed basic education in a regular school and was transferred to a secondary school for students with special needs. At 18 years of age, she presented a first psychiatric abrupt outbreak: she spent a month screaming and without sleeping. Behavioral problems then became apparent, especially hyperactivity, destructive and chaotic behavior, anxiety, and auto-aggressivity and hetero-aggressivity. A diagnosis of schizophreniform disorder was established. Clinical genetic evaluation revealed coarse face, macroglossia, coarse thick hair, and mild hepatomegaly, and the hypothesis of mucopolysaccharidosis-III was raised. Laboratory tests indicated high levels of urinary glycosaminoglycans and almost undetectable NAGLU activity, confirming the diagnosis. Sequencing of the NAGLU gene revealed the c.1318G>C (p.Gly440Arg) and c.1834A>G (p.Ser612Gly) mutations.
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Affiliation(s)
| | - Guilherme Baldo
- Instituto de Ciências, Universidade Federal do Rio Grande do Sul
| | | | | | | | - Carlos Eduardo Steiner
- Departamento de Genética Médica, Universidade de Campinas, Faculdade de Ciências Médicas, Campinas, São Paulo, Brazil
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Borda JR, Uribe-Ardila A. Determination of Reference Values for Alpha-N-Acetylglucosaminidase Activities in Patients with Sanfilippo Type B Disease and Control Population in Colombia. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2021. [DOI: 10.1590/2326-4594-jiems-2020-0023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Jones SA, Marsden D, Koutsoukos T, Sniadecki J, Tylee K, Phillippo S, Kakkis E. Retrospective chart review of urinary glycosaminoglycan excretion and long-term clinical outcomes of enzyme replacement therapy in patients with mucopolysaccharidoses. Mol Genet Metab 2020; 130:255-261. [PMID: 32563631 DOI: 10.1016/j.ymgme.2020.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 06/09/2020] [Accepted: 06/09/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Mucopolysaccharidoses (MPS) are a group of rare, inherited metabolic diseases that result from a deficiency in one of several lysosomal enzymes essential for stepwise glycosaminoglycan (GAG) degradation, leading to GAG accumulation and widespread cellular pathology and clinical disease. Although disease presentation is heterogeneous, the clinical hallmarks are largely comparable across several MPS subtypes. Extensive data have shown that the level of urinary GAG (uGAG) excretion above normal is strongly correlated with disease severity and clinical outcomes in MPS diseases. Thus, change in uGAG excretion may have significant value as a potential primary endpoint in clinical trials of MPS diseases that are too rare to study using traditional clinical endpoints. METHODS A retrospective medical chart review was undertaken of patients with MPS I, II, and VI who had been treated long term with enzyme replacement therapy (ERT). The relationship between uGAG reduction and clinical outcomes relevant to the major clinical manifestations of these MPS diseases was evaluated. A multi-domain responder index (MDRI) score was calculated, measuring the following 4 domains: 6-min walk test, pulmonary function, growth rate, and Clinician Global Impression of Change. For each domain, a minimal important difference (MID) was defined based on published information of these outcome measures in MPS and other diseases. RESULTS Of the 50 patients evaluated, 18 (36%) had MPS I, 23 (46%) had MPS II, and 9 (18%) had MPS VI. Forty-two were clinical practice patients and 8 had participated in clinical trials. Across all MPS subtypes, the mean (± SD) uGAG level at baseline was 66.0 ± 51.5 mg/mmol creatinine (n = 48) and there was a mean reduction of 54.6% following ERT. Analysis of the MDRI score based on the MID defined for each domain showed a greater magnitude of improvement in patients with increased uGAG reduction when compared with those patients with lower uGAG reduction for all assessed uGAG thresholds, and a trend toward a higher likelihood of positive mean MDRI score in patients with a uGAG reduction ≥40%. CONCLUSIONS In this retrospective study, uGAG reduction was associated with long-term clinical outcomes as assessed by a number of approaches, supporting the use of uGAG reduction as a biomarker primary endpoint.
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Affiliation(s)
- Simon A Jones
- Manchester University Hospitals NHS Foundation Trust, St Mary's Hospital, Manchester, UK.
| | | | | | | | - Karen Tylee
- Manchester University Hospitals NHS Foundation Trust, St Mary's Hospital, Manchester, UK
| | - Sarah Phillippo
- Manchester University Hospitals NHS Foundation Trust, St Mary's Hospital, Manchester, UK
| | - Emil Kakkis
- Ultragenyx Pharmaceutical Inc., Novato, CA, USA
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Saville JT, Flanigan KM, Truxal KV, McBride KL, Fuller M. Evaluation of biomarkers for Sanfilippo syndrome. Mol Genet Metab 2019; 128:68-74. [PMID: 31104888 DOI: 10.1016/j.ymgme.2019.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 05/07/2019] [Indexed: 11/16/2022]
Abstract
Sanfilippo syndrome or mucopolysaccharidosis type III (MPS III) is a childhood metabolic disorder marked by neuropathology arising due to impaired heparan sulphate (HS) catabolism. Consequently, partially degraded HS accumulates in the lysosomes of affected cells and is excreted in the urine. The measurement of HS in urine has long been considered a biomarker of Sanfilippo syndrome although it is largely non-specific. Using blood, urine and CSF collected from a cohort of Sanfilippo patients we investigated the utility of primary and secondary biomarkers to inform on disease activity. These included enzyme activity, specific oligosaccharides with non-reducing end residues reflective of the enzyme deficiency, and gangliosides. The diagnostic oligosaccharides - a HS disaccharide and tetrasaccharide - were elevated in the urine, plasma and CSF of all MPS IIIA and IIIB patients, respectively. There was no correlation between the concentrations in any of the matrices suggesting they reflect specific tissues and not overall disease burden. Enzyme activity did not inform on disease severity, with no measurable activity in CSF and activity approaching normal in MPS IIIA plasma. The concentration of gangliosides, GM2 and GM3, were significantly higher in the CSF of all MPS III subjects when compared to controls and correlated with the age of onset of first symptoms. Given that these gangliosides reflect delayed brain development they may be useful measures of disease burden, within the limitations of the clinical surrogates. Observation of these biochemical measurements in MPS III patients enrolled in clinical trials may determine whether they represent true pharmacodynamics biomarkers.
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Affiliation(s)
- Jennifer T Saville
- Genetics and Molecular Pathology, SA Pathology at Women's and Children's Hospital, 72 King William Road, North Adelaide 5006, Australia
| | - Kevin M Flanigan
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Kristen V Truxal
- The Division of Genetics and Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Kim L McBride
- The Division of Genetics and Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Maria Fuller
- Genetics and Molecular Pathology, SA Pathology at Women's and Children's Hospital, 72 King William Road, North Adelaide 5006, Australia; School of Medicine, University of Adelaide, Adelaide 5005, Australia.
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Clark WT, Yu GK, Aoyagi-Scharber M, LeBowitz JH. Utilizing ExAC to assess the hidden contribution of variants of unknown significance to Sanfilippo Type B incidence. PLoS One 2018; 13:e0200008. [PMID: 29979746 PMCID: PMC6034809 DOI: 10.1371/journal.pone.0200008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/18/2018] [Indexed: 01/30/2023] Open
Abstract
Given the large and expanding quantity of publicly available sequencing data, it should be possible to extract incidence information for monogenic diseases from allele frequencies, provided one knows which mutations are causal. We tested this idea on a rare, monogenic, lysosomal storage disorder, Sanfilippo Type B (Mucopolysaccharidosis type IIIB). Sanfilippo Type B is caused by mutations in the gene encoding α-N-acetylglucosaminidase (NAGLU). There were 189 NAGLU missense variants found in the ExAC dataset that comprises roughly 60,000 individual exomes. Only 24 of the 189 missense variants were known to be pathogenic; the remaining 165 variants were of unknown significance (VUS), and their potential contribution to disease is unknown. To address this problem, we measured enzymatic activities of 164 NAGLU missense VUS in the ExAC dataset and developed a statistical framework for estimating disease incidence with associated confidence intervals. We found that 25% of VUS decreased the activity of NAGLU to levels consistent with Sanfilippo Type B pathogenic alleles. We found that a substantial fraction of Sanfilippo Type B incidence (67%) could be accounted for by novel mutations not previously identified in patients, illustrating the utility of combining functional activity data for VUS with population-wide allele frequency data in estimating disease incidence.
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Affiliation(s)
- Wyatt T. Clark
- BioMarin Pharmaceutical, San Rafael, CA, United States of America
| | - G. Karen Yu
- BioMarin Pharmaceutical, San Rafael, CA, United States of America
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Whitley CB, Cleary M, Eugen Mengel K, Harmatz P, Shapiro E, Nestrasil I, Haslett P, Whiteman D, Alexanderian D. Observational Prospective Natural History of Patients with Sanfilippo Syndrome Type B. J Pediatr 2018; 197:198-206.e2. [PMID: 29661560 DOI: 10.1016/j.jpeds.2018.01.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/05/2017] [Accepted: 01/12/2018] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To evaluate the natural course of disease progression in patients with Sanfilippo syndrome type B (mucopolysaccharidosis type IIIB), identify potential end points for future therapy trials, and characterize biomarkers related to the disease. STUDY DESIGN A prospective, multicenter study was conducted. Baseline, 6-month, and 12-month assessments included neurodevelopmental status (Bayley Scales of Infant Development, Third edition), adaptive status (Vineland Adaptive Behavior Scales, Second Edition), volumetric brain magnetic resonance imaging, cerebrospinal fluid heparan sulfate, and urine glycosaminoglycan (GAG) measurements. RESULTS Nineteen patients aged 1.6-31.7 years were enrolled. Over 12 months, cognition, adaptive behavior, and cortical gray matter volume (GMV) declined in most patients. For patients diagnosed at <6 years, although there was no overall mean change over 12 months, there were 10%-48%, 3%-66%, and 1%-14% decreases in cognitive development quotient score, Vineland Adaptive Behavior Scales, Second Edition development quotient score, and cortical GMV in 8/12, 9/11, and 10/11 patients, respectively. Mean urine GAG and cerebrospinal fluid heparan sulfate levels were stable, but patients diagnosed at <6 years (n = 14) had higher levels than those ≥6 years at diagnosis (n = 4), which was likely associated with age as they also were generally younger. CONCLUSIONS Cognition, adaptive behavior, and cortical GMV measures sensitively tracked deterioration in patients with mucopolysaccharidosis type IIIB aged ≤8.6 years. Biomarkers may have prognostic value, but their sensitivity to disease progression requires further investigation. These findings should help evaluate enzyme replacement and gene therapy agents for this rare, devastating, neurodegenerative disease. TRIAL REGISTRATION ClinicalTrials.gov: NCT01509768.
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Affiliation(s)
| | | | - Karl Eugen Mengel
- Villa Metabolica, Center for Pediatric and Adolescent Medicine, MC University of Mainz, Mainz, Germany
| | - Paul Harmatz
- UCSF Benioff Children's Hospital Oakland, Oakland, CA
| | - Elsa Shapiro
- Shapiro Neuropsychology Consulting LLC, Portland, OR; Department of Pediatrics, University of Minnesota, Minneapolis, MN
| | - Igor Nestrasil
- Department of Pediatrics, University of Minnesota, Minneapolis, MN
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Nijmeijer SCM, Wijburg FA. Mucopolysaccharidosis type III: current clinical trials, challenges and recommendations. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2018.1411797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Stephanie CM Nijmeijer
- Department of Pediatric Metabolic Diseases, Emma Children’s Hospital and Amsterdam Lysosome Center ‘Sphinx,’ Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Frits A Wijburg
- Department of Pediatric Metabolic Diseases, Emma Children’s Hospital and Amsterdam Lysosome Center ‘Sphinx,’ Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Knottnerus SJG, Nijmeijer SCM, IJlst L, Te Brinke H, van Vlies N, Wijburg FA. Prediction of phenotypic severity in mucopolysaccharidosis type IIIA. Ann Neurol 2017; 82:686-696. [PMID: 29023963 PMCID: PMC5725696 DOI: 10.1002/ana.25069] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/11/2017] [Accepted: 10/02/2017] [Indexed: 01/03/2023]
Abstract
Objective Mucopolysaccharidosis IIIA or Sanfilippo disease type A is a progressive neurodegenerative disorder presenting in early childhood, caused by an inherited deficiency of the lysosomal hydrolase sulfamidase. New missense mutations, for which genotype–phenotype correlations are currently unknown, are frequently reported, hampering early prediction of phenotypic severity and efficacy assessment of new disease‐modifying treatments. We aimed to design a method to determine phenotypic severity early in the disease course. Methods Fifty‐three patients were included for whom skin fibroblasts and data on disease course and mutation analysis were available. Patients were phenotypically characterized on clinical data as rapidly progressing or slowly progressing. Sulfamidase activity was measured in fibroblasts cultured at 37 °C and at 30 °C. Results Sulfamidase activity in fibroblasts from patients homozygous or compound heterozygous for a combination of known severe mutations remained below the limit of quantification under both culture conditions. In contrast, sulfamidase activity in fibroblasts from patients homozygous or compound heterozygous for a known mild mutation increased above the limit of quantification when cultured at 30 °C. With division on the basis of the patients' phenotype, fibroblasts from slowly progressing patients could be separated from rapidly progressing patients by increase in sulfamidase activity when cultured at 30 °C (p < 0.001, sensitivity = 96%, specificity = 93%). Interpretation Phenotypic severity strongly correlates with the potential to increase sulfamidase activity in fibroblasts cultured at 30 °C, allowing reliable distinction between patients with rapidly progressing or slowly progressing phenotypes. This method may provide an essential tool for assessment of treatment effects and for health care and life planning decisions. Ann Neurol 2017;82:686–696
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Affiliation(s)
- Suzan J G Knottnerus
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx," Academic Medical Center, University of Amsterdam.,Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Stephanie C M Nijmeijer
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx," Academic Medical Center, University of Amsterdam
| | - Lodewijk IJlst
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Heleen Te Brinke
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Naomi van Vlies
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Frits A Wijburg
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx," Academic Medical Center, University of Amsterdam.,Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Meijer OLM, Te Brinke H, Ofman R, IJlst L, Wijburg FA, van Vlies N. Processing of mutant N-acetyl-α-glucosaminidase in mucopolysaccharidosis type IIIB fibroblasts cultured at low temperature. Mol Genet Metab 2017; 122:100-106. [PMID: 28751108 DOI: 10.1016/j.ymgme.2017.07.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND The autosomal recessive, neurodegenerative disorder mucopolysaccharidosis type IIIB (MPSIIIB) is caused by a deficiency of the lysosomal enzyme N-acetyl-α-glucosaminidase (NAGLU), resulting in accumulation of heparan sulfate. The disease spectrum comprises a severe, rapidly progressing (RP) phenotype and a more attenuated, slowly progressing (SP) phenotype. Previous studies showed significantly higher NAGLU activity in skin fibroblasts of SP patients when cultured at 30°C which may be relevant for development of novel therapeutic strategies. Here we report on the processes involved in this phenomenon. METHODS Fibroblasts from controls, one RP patient (homozygous for the p.R297* mutation) and three SP MPSIIIB patients (homozygous for the mutation p.S612G or p.R643C, or compound heterozygous for the mutations p.A72_G79dup8 and p.R565Q) were cultured at temperatures ranging from 37°C to 27°C and harvested at different time points to assess NAGLU activity, mRNA and protein levels, and NAGLU glycosylation. Intracellular localization of wild-type and mutant mCherry-tagged NAGLU was analyzed by immunofluorescence. RESULTS In control fibroblasts NAGLU was present as a 85kDa precursor and a 82kDa mature form. In SP patients' fibroblasts cultured at 37°C, only the 85kDa form was detected. Culturing at lower temperatures resulted in higher NAGLU mRNA levels, increased levels of both precursor and mature NAGLU protein and improved processing. The formation of mature NAGLU corresponded with higher NAGLU activity levels. CONCLUSION We show that the NAGLU protein consists of a precursor and a mature form and that in SP MPSIIIB patients' fibroblasts only the precursor protein is present at 37°C. Culturing at lower temperatures resulted in the formation of the mature, enzymatically active form, due to higher mRNA levels and improved processing.
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Affiliation(s)
- O L M Meijer
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx", Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - H Te Brinke
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - R Ofman
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - L IJlst
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - F A Wijburg
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx", Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - N van Vlies
- Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx", Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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14
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Meijer OLM, van den Biggelaar P, Ofman R, Wijburg FA, van Vlies N. High-Throughput Screen Fails to Identify Compounds That Enhance Residual Enzyme Activity of Mutant N-Acetyl-α-Glucosaminidase in Mucopolysaccharidosis Type IIIB. JIMD Rep 2017; 39:97-106. [PMID: 28836185 PMCID: PMC5953891 DOI: 10.1007/8904_2017_51] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/19/2017] [Accepted: 07/24/2017] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND In the severe neurodegenerative disorder mucopolysaccharidosis type IIIB (MPSIIIB or Sanfilippo disease type B), deficiency of the lysosomal enzyme N-acetyl-α-glucosaminidase (NAGLU) results in accumulation of heparan sulfate. Patients present with a severe, rapidly progressing phenotype (RP) or a more attenuated, slowly progressing phenotype (SP). In a previous study, residual NAGLU activity in fibroblasts of SP patients could be increased by culturing at 30°C, probably as a result of improved protein folding and lysosomal targeting under these conditions. Chaperones are molecules which influence protein folding and could therefore have therapeutic potential in SP MPSIIIB patients. Here we studied the effects of 1,302 different compounds on residual NAGLU activity in SP MPSIIIB patient fibroblasts including 1,280 approved compounds from the Prestwick Chemical Library. METHODS Skin fibroblasts of healthy controls, an SP MPSIIIB patient (homozygous for the temperature sensitive mutation p.S612G) and an RP MPSIIIB patient (homozygous for the p.R297* mutation and non-temperature sensitive), were used. A high-throughput assay for measurement of NAGLU activity was developed and validated, after which 1,302 different molecules were tested for their potential to increase NAGLU activity. RESULTS None of the compounds tested were able to enhance NAGLU activity. CONCLUSIONS This high-throughput screen failed to identify compounds that could enhance residual activity of mutant NAGLU in fibroblasts of SP MPSIIIB patients with temperature sensitive mutations. To therapeutically simulate the positive effect of lower temperatures on residual NAGLU activity, first more insight is needed into the mechanisms underlying this temperature dependent increase.
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Affiliation(s)
- O. L. M. Meijer
- Department of Pediatric Metabolic Diseases, Emma Children’s Hospital and Amsterdam Lysosome Center “Sphinx”, Academic Medical Center, Amsterdam, The Netherlands ,Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands
| | - P. van den Biggelaar
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands
| | - R. Ofman
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands
| | - F. A. Wijburg
- Department of Pediatric Metabolic Diseases, Emma Children’s Hospital and Amsterdam Lysosome Center “Sphinx”, Academic Medical Center, Amsterdam, The Netherlands
| | - N. van Vlies
- Department of Pediatric Metabolic Diseases, Emma Children’s Hospital and Amsterdam Lysosome Center “Sphinx”, Academic Medical Center, Amsterdam, The Netherlands ,Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry, Academic Medical Center, Amsterdam, The Netherlands ,Intravacc, Institute for Translational Vaccinology, Bilthoven, The Netherlands
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15
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Hemsley K, Lau A. Intracerebral gene therapy for mucopolysaccharidosis type IIIB syndrome. Lancet Neurol 2017; 16:681-682. [PMID: 28713036 DOI: 10.1016/s1474-4422(17)30200-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 06/08/2017] [Indexed: 10/19/2022]
Affiliation(s)
- Kim Hemsley
- Lysosomal Diseases Research Unit, Nutrition and Metabolism Theme, South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia.
| | - Adeline Lau
- Lysosomal Diseases Research Unit, Nutrition and Metabolism Theme, South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia
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16
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Martins C, Brunel-Guitton C, Lortie A, Gauvin F, Morales CR, Mitchell GA, Pshezhetsky AV. Atypical juvenile presentation of G M2 gangliosidosis AB in a patient compound-heterozygote for c.259G > T and c.164C > T mutations in the GM2A gene. Mol Genet Metab Rep 2017; 11:24-29. [PMID: 28417072 PMCID: PMC5388932 DOI: 10.1016/j.ymgmr.2017.01.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 01/18/2017] [Accepted: 01/18/2017] [Indexed: 01/22/2023] Open
Abstract
GM2-gangliosidosis, AB variant is an extremely rare autosomal recessive inherited disorder caused by mutations in the GM2A gene that encodes GM2 ganglioside activator protein (GM2AP). GM2AP is necessary for solubilisation of GM2 ganglioside in endolysosomes and its presentation to β-hexosaminidase A. Conversely GM2AP deficiency impairs lysosomal catabolism of GM2 ganglioside, leading to its storage in cells and tissues. We describe a 9-year-old child with an unusual juvenile clinical onset of GM2-gangliosidosis AB. At the age of 3 years he presented with global developmental delay, progressive epilepsy, intellectual disability, axial hypertonia, spasticity, seizures and ataxia, but without the macular cherry-red spots typical for GM2 gangliosidosis. Brain MRI detected a rapid onset of diffuse atrophy, whereas whole exome sequencing showed that the patient is a compound heterozygote for two mutations in GM2A: a novel nonsense mutation, c.259G > T (p.E87X) and a missense mutation c.164C > T (p.P55L) that was recently identified in homozygosity in patients of a Saudi family with a progressive chorea-dementia syndrome. Western blot analysis showed an absence of GM2AP in cultured fibroblasts from the patient, suggesting that both mutations interfere with the synthesis and/or folding of the protein. Finally, impaired catabolism of GM2 ganglioside in the patient's fibroblasts was demonstrated by metabolic labeling with fluorescently labeled GM1 ganglioside and by immunohistochemistry with anti-GM2 and anti-GM3 antibodies. Our observation expands the molecular and clinical spectrum of molecular defects linked to GM2-gangliosidosis and suggests novel diagnostic approach by whole exome sequencing and perhaps ganglioside analysis in cultured patient's cells.
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Affiliation(s)
- Carla Martins
- CHU Ste-Justine, University of Montreal, Montreal, QC, Canada
| | | | - Anne Lortie
- CHU Ste-Justine, University of Montreal, Montreal, QC, Canada
| | - France Gauvin
- CHU Ste-Justine, University of Montreal, Montreal, QC, Canada
| | - Carlos R Morales
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
| | | | - Alexey V Pshezhetsky
- CHU Ste-Justine, University of Montreal, Montreal, QC, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
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17
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Stütz AE, Wrodnigg TM. Carbohydrate-Processing Enzymes of the Lysosome: Diseases Caused by Misfolded Mutants and Sugar Mimetics as Correcting Pharmacological Chaperones. Adv Carbohydr Chem Biochem 2016; 73:225-302. [PMID: 27816107 DOI: 10.1016/bs.accb.2016.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lysosomal storage diseases are hereditary disorders caused by mutations on genes encoding for one of the more than fifty lysosomal enzymes involved in the highly ordered degradation cascades of glycans, glycoconjugates, and other complex biomolecules in the lysosome. Several of these metabolic disorders are associated with the absence or the lack of activity of carbohydrate-processing enzymes in this cell compartment. In a recently introduced therapy concept, for susceptible mutants, small substrate-related molecules (so-called pharmacological chaperones), such as reversible inhibitors of these enzymes, may serve as templates for the correct folding and transport of the respective protein mutant, thus improving its concentration and, consequently, its enzymatic activity in the lysosome. Carbohydrate-processing enzymes in the lysosome, related lysosomal diseases, and the scope and limitations of reported reversible inhibitors as pharmacological chaperones are discussed with a view to possibly extending and improving research efforts in this area of orphan diseases.
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Affiliation(s)
- Arnold E Stütz
- Glycogroup, Institute of Organic Chemistry, Graz University of Technology, Graz, Austria
| | - Tanja M Wrodnigg
- Glycogroup, Institute of Organic Chemistry, Graz University of Technology, Graz, Austria
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