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Li H, Doray B, Jennings BC, Lee WS, Liu L, Kornfeld S, Li H. Structure of a truncated human GlcNAc-1-phosphotransferase variant reveals the basis for its hyperactivity. J Biol Chem 2024:107706. [PMID: 39178950 DOI: 10.1016/j.jbc.2024.107706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 07/30/2024] [Accepted: 08/08/2024] [Indexed: 08/26/2024] Open
Abstract
Mutations that cause loss of function of GlcNAc-1-phosphotransferase (PTase) lead to the lysosomal storage disorder mucolipidosis II. PTase is the key enzyme of the mannose 6-phosphate (M6P) targeting system that is responsible for tagging lysosomal hydrolases with the M6P moiety for their delivery to the lysosome. We had previously generated a truncated hyperactive form of PTase termed S1S3 which was shown to notably increase the phosphorylation level of secreted lysosomal enzymes and enhance their uptake by cells. Here, we report the 3.4 Å cryo-EM structure of soluble S1S3 lacking both transmembrane domains and cytosolic tails. The structure reveals a high degree of conservation of the catalytic core to full-length PTase. In this dimeric structure, the EF hand of one protomer is observed interacting with the conserved region 4 of the other. In addition, we present a high-quality EM 3D map of the UDP-GlcNAc bound form of the full-length soluble protein showing the key molecular interactions between the nucleotide sugar donor and side chain amino acids of the protein. Finally, although the domain organization of S1S3 is very similar to that of the Drosophila melanogaster (fruit fly) PTase homolog, we establish that the latter does not act on lysosomal hydrolases.
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Affiliation(s)
- Hua Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Benjamin C Jennings
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Wang-Sik Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Lin Liu
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA.
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2
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Lee JJ, Wang T, Wiggins K, Lu PN, Underwood C, Ochenkowska K, Samarut E, Pollard LM, Flanagan-Steet H, Steet R. Dysregulated lysosomal exocytosis drives protease-mediated cartilage pathogenesis in multiple lysosomal disorders. iScience 2024; 27:109293. [PMID: 38495824 PMCID: PMC10940929 DOI: 10.1016/j.isci.2024.109293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 12/20/2023] [Accepted: 02/16/2024] [Indexed: 03/19/2024] Open
Abstract
The classic view of the lysosome as a static recycling center has been replaced with one of a dynamic and mobile hub of metabolic regulation. This revised view raises new questions about how dysfunction of this organelle causes pathology in inherited lysosomal disorders. Here we provide evidence for increased lysosomal exocytosis in the developing cartilage of three lysosomal disease zebrafish models with distinct etiologies. Dysregulated exocytosis was linked to altered cartilage development, increased activity of multiple cathepsin proteases, and cathepsin- and TGFβ-mediated pathogenesis in these models. Moreover, inhibition of cathepsin activity or direct blockade of exocytosis with small molecule modulators improved the cartilage phenotypes, reinforcing a connection between excessive extracellular protease activity and cartilage pathogenesis. This study highlights the pathogenic consequences in early cartilage development arising from uncontrolled release of lysosomal enzymes via exocytosis, and suggests that pharmacological enhancement of this process could be detrimental during tissue development.
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Affiliation(s)
- Jen-Jie Lee
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Tong Wang
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Kali Wiggins
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Po Nien Lu
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Christina Underwood
- Biochemical Genetics Laboratory, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Katarzyna Ochenkowska
- Research Center, Centre hospitalier de l’Université de Montréal (CHUM), Montreal, Canada
- Department of Neuroscience, Université de Montréal, Montréal, Canada
| | - Eric Samarut
- Research Center, Centre hospitalier de l’Université de Montréal (CHUM), Montreal, Canada
- Department of Neuroscience, Université de Montréal, Montréal, Canada
| | - Laura M. Pollard
- Biochemical Genetics Laboratory, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | | | - Richard Steet
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
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Gul R, Firasat S, Schubert M, Ullah A, Peña E, Thuesen ACB, Gjesing AP, Hussain M, Tufail M, Saqib M, Afshan K, Hansen T. Identification of genetic variants associated with a wide spectrum of phenotypes clinically diagnosed as Sanfilippo and Morquio syndromes using whole genome sequencing. Front Genet 2023; 14:1254909. [PMID: 37772257 PMCID: PMC10524275 DOI: 10.3389/fgene.2023.1254909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 08/17/2023] [Indexed: 09/30/2023] Open
Abstract
Mucopolysaccharidoses (MPSs) are inherited lysosomal storage disorders (LSDs). MPSs are caused by excessive accumulation of mucopolysaccharides due to missing or deficiency of enzymes required for the degradation of specific macromolecules. MPS I-IV, MPS VI, MPS VII, and MPS IX are sub-types of mucopolysaccharidoses. Among these, MPS III (also known as Sanfilippo) and MPS IV (Morquio) syndromes are lethal and prevalent sub-types. This study aimed to identify causal genetic variants in cases of MPS III and MPS IV and characterize genotype-phenotype relations in Pakistan. We performed clinical, biochemical and genetic analysis using Whole Genome Sequencing (WGS) in 14 Pakistani families affected with MPS III or MPS IV. Patients were classified into MPS III by history of aggressive behaviors, dementia, clear cornea and into MPS IV by short trunk, short stature, reversed ratio of upper segment to lower segment with a short upper segment. Data analysis and variant selections were made based on segregation analysis, examination of known MPS III and MPS IV genes, gene function, gene expression, the pathogenicity of variants based on ACMG guidelines and in silico analysis. In total, 58 individuals from 14 families were included in the present study. Six families were clinically diagnosed with MPS III and eight families with MPS IV. WGS revealed variants in MPS-associated genes including NAGLU, SGSH, GALNS, GNPTG as well as the genes VWA3B, BTD, and GNPTG which have not previously associated with MPS. One family had causal variants in both GALNS and BTD. Accurate and early diagnosis of MPS in children represents a helpful step for designing therapeutic strategies to protect different organs from permanent damage. In addition, pre-natal screening and identification of genetic etiology will facilitate genetic counselling of the affected families. Identification of novel causal MPS genes might help identifying new targeted therapies to treat LSDs.
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Affiliation(s)
- Rutaba Gul
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sabika Firasat
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Mikkel Schubert
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Asmat Ullah
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elionora Peña
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne C. B. Thuesen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Annete P. Gjesing
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mulazim Hussain
- The Children Hospital, Pakistan Institute of Medical Sciences (PIMS), Islamabad, Pakistan
| | - Muhammad Tufail
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Muhammad Saqib
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
- Department of Zoology, University of Lakki Marwat, Lakki Marwat, Khyber Pakhtunkhwa, Pakistan
| | - Kiran Afshan
- Department of Zoology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Torben Hansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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4
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Li H, Lee WS, Feng X, Bai L, Jennings BC, Liu L, Doray B, Canfield WM, Kornfeld S, Li H. Structure of the human GlcNAc-1-phosphotransferase αβ subunits reveals regulatory mechanism for lysosomal enzyme glycan phosphorylation. Nat Struct Mol Biol 2022; 29:348-356. [PMID: 35332324 PMCID: PMC9018626 DOI: 10.1038/s41594-022-00748-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/16/2022] [Indexed: 02/07/2023]
Abstract
Vertebrates use the mannose 6-phosphate (M6P)-recognition system to deliver lysosomal hydrolases to lysosomes. Key to this pathway is N-acetylglucosamine (GlcNAc)-1-phosphotransferase (PTase) that selectively adds GlcNAc-phosphate (P) to mannose residues of hydrolases. Human PTase is an α2β2γ2 heterohexamer with a catalytic core and several peripheral domains that recognize and bind substrates. Here we report a cryo-EM structure of the catalytic core of human PTase and the identification of a hockey stick-like motif that controls activation of the enzyme. Movement of this motif out of the catalytic pocket is associated with a rearrangement of part of the peripheral domains that unblocks hydrolase glycan access to the catalytic site, thereby activating PTase. We propose that PTase fluctuates between inactive and active states in solution, and selective substrate binding of a lysosomal hydrolase through its protein-binding determinant to PTase locks the enzyme in the active state to permit glycan phosphorylation. This mechanism would help ensure that only N-linked glycans of lysosomal enzymes are phosphorylated.
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Affiliation(s)
- Hua Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Wang-Sik Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiang Feng
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Lin Bai
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Benjamin C Jennings
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Lin Liu
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
- M6P Therapeutics, St. Louis, MO, USA
| | - Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA.
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Oussoren E, Wagenmakers MAEM, Link B, van der Meijden JC, Pijnappel WWMP, Ruijter GJG, Langeveld M, van der Ploeg AT. Hip disease in Mucopolysaccharidoses and Mucolipidoses: A review of mechanisms, interventions and future perspectives. Bone 2021; 143:115729. [PMID: 33130340 DOI: 10.1016/j.bone.2020.115729] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 11/20/2022]
Abstract
The hips are frequently involved in inheritable diseases which affect the bones. The clinical and radiological presentation of these diseases may be very similar to common hip disorders as developmental dysplasia of the hip, osteoarthritis and avascular necrosis, so the diagnosis may be easily overlooked and treatment may be suboptimal. Mucopolysaccharidosis (MPS) and Mucolipidosis (ML II and III) are lysosomal storage disorders with multisystemic involvement. Characteristic skeletal abnormalities, known as dysostosis multiplex, are common in MPS and ML and originate from intra-lysosomal storage of glycosaminoglycans in cells of the cartilage, bones and ligaments. The hip joint is severely affected in MPS and ML. Hip pathology results in limitations in mobility and pain from young age, and negatively affects quality of life. In order to better understand the underlying process that causes hip disease in MPS and ML, this review first describes the normal physiological (embryonic) hip joint development, including the interplay between the acetabulum and the femoral head. In the second part the factors contributing to altered hip morphology and function in MPS and ML are discussed, such as abnormal development of the pelvic- and femoral bones (which results in altered biomechanical forces) and inflammation. In the last part of this review therapeutic options and future perspectives are addressed.
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Affiliation(s)
- Esmee Oussoren
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Margreet A E M Wagenmakers
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Bianca Link
- Division of Metabolism, Connective Tissue Unit, University Children's Hospital Zurich, Zurich, Switzerland.
| | - Jan C van der Meijden
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - W W M Pim Pijnappel
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - George J G Ruijter
- Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Mirjam Langeveld
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.
| | - Ans T van der Ploeg
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
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6
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Mucolipidoses Overview: Past, Present, and Future. Int J Mol Sci 2020; 21:ijms21186812. [PMID: 32957425 PMCID: PMC7555117 DOI: 10.3390/ijms21186812] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
Mucolipidosis II and III (ML II/III) are caused by a deficiency of uridine-diphosphate N-acetylglucosamine: lysosomal-enzyme-N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase, EC2.7.8.17), which tags lysosomal enzymes with a mannose 6-phosphate (M6P) marker for transport to the lysosome. The process is performed by a sequential two-step process: first, GlcNAc-1-phosphotransferase catalyzes the transfer of GlcNAc-1-phosphate to the selected mannose residues on lysosomal enzymes in the cis-Golgi network. The second step removes GlcNAc from lysosomal enzymes by N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase (uncovering enzyme) and exposes the mannose 6-phosphate (M6P) residues in the trans-Golgi network, in which the enzymes are targeted to the lysosomes by M6Preceptors. A deficiency of GlcNAc-1-phosphotransferase causes the hypersecretion of lysosomal enzymes out of cells, resulting in a shortage of multiple lysosomal enzymes within lysosomes. Due to a lack of GlcNAc-1-phosphotransferase, the accumulation of cholesterol, phospholipids, glycosaminoglycans (GAGs), and other undegraded substrates occurs in the lysosomes. Clinically, ML II and ML III exhibit quite similar manifestations to mucopolysaccharidoses (MPSs), including specific skeletal deformities known as dysostosis multiplex and gingival hyperplasia. The life expectancy is less than 10 years in the severe type, and there is no definitive treatment for this disease. In this review, we have described the updated diagnosis and therapy on ML II/III.
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Yang C, Pan J, Linpeng S, Li Z, Tan H, Wu L. Identification of Five Novel Mutations Causing Rare Lysosomal Storage Diseases. Med Sci Monit 2019; 25:7634-7644. [PMID: 31603145 PMCID: PMC6800466 DOI: 10.12659/msm.915876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 06/06/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Lysosomal storage diseases (LSDs), a group of rare inherited metabolic disorders, result from specific lysosomal proteins deficiencies in the degradation of biomacromolecule, including over 70 different diseases, most of which are autosomal recessive. LSDs are multisystem disorders, and the clinical manifestations are usually broad and severe, involving the skeletal system, central nervous system (CNS), cardiovascular system, etc. Besides, patients with some subtypes of LSD have distinctive facial features. MATERIAL AND METHODS We performed next generation sequencing on 4 suspected mucopolysaccharidosis (MPS) cases to determine the genetic causes of the disease. By in vitro molecular cell assay, such as real-time polymerase chain reaction (RT-PCR) and western blot, we tested the pathogenicity of candidate variants. RESULTS We detected 5 novel mutations in 4 patients. The mutations were: c.211_214del and c.1270C>T in GUSB; c.1284+1C>A and c.2404C>T in GNPTAB; and c.717C>A in FUCA1). We identified a rare mucopolysaccharidosis VII patient, a rare fucosidosis patient, and 2 rare mucolipidosis II patients, one of which was an atypical patient. We also present a new pathogenic conjecture about a small deletion in GUSB. CONCLUSIONS Our study described rare diseases in Chinese patients and our results enrich the phenotype spectrum of related diseases, as well as mutation spectrum of related genes, which might be significant for clinical disease diagnosis and prenatal diagnosis.
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Dhakal S, Lee Y. Transient Receptor Potential Channels and Metabolism. Mol Cells 2019; 42:569-578. [PMID: 31446746 PMCID: PMC6715338 DOI: 10.14348/molcells.2019.0007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 07/27/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022] Open
Abstract
Transient receptor potential (TRP) channels are nonselective cationic channels, conserved among flies to humans. Most TRP channels have well known functions in chemosensation, thermosensation, and mechanosensation. In addition to being sensing environmental changes, many TRP channels are also internal sensors that help maintain homeostasis. Recent improvements to analytical methods for genomics and metabolomics allow us to investigate these channels in both mutant animals and humans. In this review, we discuss three aspects of TRP channels, which are their role in metabolism, their functional characteristics, and their role in metabolic syndrome. First, we introduce each TRP channel superfamily and their particular roles in metabolism. Second, we provide evidence for which metabolites TRP channels affect, such as lipids or glucose. Third, we discuss correlations between TRP channels and obesity, diabetes, and mucolipidosis. The cellular metabolism of TRP channels gives us possible therapeutic approaches for an effective prophylaxis of metabolic syndromes.
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Affiliation(s)
- Subash Dhakal
- Department of Bio and Fermentation Convergence Technology, Kookmin University, BK21 PLUS Project, Seoul 02707,
Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, BK21 PLUS Project, Seoul 02707,
Korea
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9
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Velho RV, Harms FL, Danyukova T, Ludwig NF, Friez MJ, Cathey SS, Filocamo M, Tappino B, Güneş N, Tüysüz B, Tylee KL, Brammeier KL, Heptinstall L, Oussoren E, van der Ploeg AT, Petersen C, Alves S, Saavedra GD, Schwartz IV, Muschol N, Kutsche K, Pohl S. The lysosomal storage disorders mucolipidosis type II, type III alpha/beta, and type III gamma: Update on GNPTAB and GNPTG mutations. Hum Mutat 2019; 40:842-864. [PMID: 30882951 DOI: 10.1002/humu.23748] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/19/2019] [Accepted: 03/14/2019] [Indexed: 01/04/2023]
Abstract
Mutations in the GNPTAB and GNPTG genes cause mucolipidosis (ML) type II, type III alpha/beta, and type III gamma, which are autosomal recessively inherited lysosomal storage disorders. GNPTAB and GNPTG encode the α/β-precursor and the γ-subunit of N-acetylglucosamine (GlcNAc)-1-phosphotransferase, respectively, the key enzyme for the generation of mannose 6-phosphate targeting signals on lysosomal enzymes. Defective GlcNAc-1-phosphotransferase results in missorting of lysosomal enzymes and accumulation of non-degradable macromolecules in lysosomes, strongly impairing cellular function. MLII-affected patients have coarse facial features, cessation of statural growth and neuromotor development, severe skeletal abnormalities, organomegaly, and cardiorespiratory insufficiency leading to death in early childhood. MLIII alpha/beta and MLIII gamma are attenuated forms of the disease. Since the identification of the GNPTAB and GNPTG genes, 564 individuals affected by MLII or MLIII have been described in the literature. In this report, we provide an overview on 258 and 50 mutations in GNPTAB and GNPTG, respectively, including 58 novel GNPTAB and seven novel GNPTG variants. Comprehensive functional studies of GNPTAB missense mutations did not only gain insights into the composition and function of the GlcNAc-1-phosphotransferase, but also helped to define genotype-phenotype correlations to predict the clinical outcome in patients.
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Affiliation(s)
- Renata Voltolini Velho
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tatyana Danyukova
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nataniel F Ludwig
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Post-Graduation Program in Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | | | - Mirella Filocamo
- Laboratorio di Genetica Molecolare e Biobanche, Istituto Giannina Gaslini, Genova, Italy
| | - Barbara Tappino
- Laboratorio di Genetica Molecolare e Biobanche, Istituto Giannina Gaslini, Genova, Italy
| | - Nilay Güneş
- Department of Pediatric Genetics, Istanbul University Cerrahpasa, Medicine School, Istanbul, Turkey
| | - Beyhan Tüysüz
- Department of Pediatric Genetics, Istanbul University Cerrahpasa, Medicine School, Istanbul, Turkey
| | - Karen L Tylee
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Kathryn L Brammeier
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Lesley Heptinstall
- Genomic Diagnostics Laboratory, Manchester Centre for Genomic Medicine, Manchester University NHS Foundation Trust, Saint Mary's Hospital, Manchester, UK
| | - Esmee Oussoren
- Department of Pediatrics, Center for LyMannose phosphorylation in health and diseasesosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Ans T van der Ploeg
- Department of Pediatrics, Center for LyMannose phosphorylation in health and diseasesosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Christine Petersen
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Alves
- Department of Human Genetics, INSA, National Health Institute Doutor Ricardo Jorge, Porto, Portugal
| | - Gloria Durán Saavedra
- División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ida V Schwartz
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Post-Graduation Program in Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Nicole Muschol
- International Center for Lysosomal Disorders, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Pohl
- Section Cell Biology of Rare Diseases, Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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10
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Wang Y, Ye J, Qiu WJ, Han LS, Gao XL, Liang LL, Gu XF, Zhang HW. Identification of predominant GNPTAB gene mutations in Eastern Chinese patients with mucolipidosis II/III and a prenatal diagnosis of mucolipidosis II. Acta Pharmacol Sin 2019; 40:279-287. [PMID: 29872134 DOI: 10.1038/s41401-018-0023-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/28/2018] [Indexed: 11/09/2022] Open
Abstract
Mucolipidosis II α/β, mucolipidosis III α/β, and mucolipidosis III γ are autosomal recessive disorders belonging to the family of lysosomal storage disorders caused by deficiency of the UDP-N-acetylglucosamine, a lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase) localized in the Golgi apparatus, which is essential for normal processing and packaging of soluble lysosomal enzymes with initiating the first step of tagging lysosomal enzymes with mannose-6-phosphate (M6P). Mucolipidosis II and III are caused by mutations in the GNPTAB and GNPTG genes, and patients with these diseases are characterized by short stature, skeletal abnormalities, and developmental delay. In this study we report 38 patients with mucolipidosis II and III enrolled in Eastern China during the past 8 years. The diagnosis was made based on clinical characteristics and measurement of plasma lysosomal enzyme activity. Sanger sequencing of GNPTAB and/or GNPTG for all patients and real-time quantitative PCR were performed to confirm the diagnosis. In addition, 11 cases of prenatal mucolipidosis II were diagnosed based on measurement of the enzyme activity in amniotic fluid supernatant and genetic testing of cultured amniotic cells. Based on molecular genetic tests, 30 patients were diagnosed with mucolipidosis II α/β, 6 were diagnosed with III α/β and 2 were diagnosed with III γ. Thirty-seven different GNPTAB gene mutations were identified in 29 patients with mucolipidosis II α/β and six patients with III α/β. These mutations included 22 new mutations (p.W44X, p.E279X, p.W416X, p.W463X, p.Q802X, p.Q882X, p.A34P, p.R334P, p.D408N, p.D534N, p.Y997C, p.D1018V, p.L1025S, p.L1033P, c.88_89delAC, c.890_891insT, c.1150_1151insTTA, c.1523delG, c.2473_2474insA, c.2980_2983delGCCT, c.3094delA, and deletion of exon 9). Four new GNPTG gene mutations were identified (c.13delC, p.Y81X, p.G126R and c.609+1delG) in two mucolipidosis III γ patients. Among the 11 cases of prenatal diagnosis, four were mucolipidosis II fetuses, three were heterozygous, and the remaining four were normal fetuses. This study expands the mutation spectrum of the GNPTAB and GNPTG genes and contributes to specific knowledge of mucolipidosis II/III in a population from Eastern China.
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11
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Oussoren E, van Eerd D, Murphy E, Lachmann R, van der Meijden JC, Hoefsloot LH, Verdijk R, Ruijter GJG, Maas M, Hollak CEM, Langendonk JG, van der Ploeg AT, Langeveld M. Mucolipidosis type III, a series of adult patients. J Inherit Metab Dis 2018; 41:839-848. [PMID: 29704188 PMCID: PMC6133174 DOI: 10.1007/s10545-018-0186-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/04/2018] [Accepted: 04/10/2018] [Indexed: 01/29/2023]
Abstract
BACKGROUND Mucolipidosis type III α/β or γ (MLIII) are rare autosomal recessive diseases, in which reduced activity of the enzyme UDP-N-acetyl glucosamine-1-phosphotransferase (GlcNAc-PTase) leads to intra-lysosomal accumulation of different substrates. Publications on the natural history of MLIII, especially the milder forms, are scarce. This study provides a detailed description of the disease characteristics and its natural course in adult patients with MLIII. METHODS In this retrospective chart study, the clinical, biochemical and molecular findings in adult patients with a confirmed diagnosis of MLIII from three treatment centres were collected. RESULTS Thirteen patients with MLIII were included in this study. Four patients (31%) were initially misdiagnosed with a type of mucopolysaccharidosis (MPS). Four patients (31%) had mild cognitive impairment. Six patients (46%) needed help with activities of daily living (ADL) or were wheelchair-dependent. All patients had dysostosis multiplex and progressive secondary osteoarthritis, characterised by cartilage destruction and bone lesions in multiple joints. All patients underwent multiple orthopaedic surgical interventions as early as the second or third decades of life, of which total hip replacement (THR) was the most common procedure (61% of patients). Carpal tunnel syndrome (CTS) was found in 12 patients (92%) and in eight patients (61%), CTS release was performed. CONCLUSIONS Severe skeletal abnormalities, resulting from abnormal bone development and severe progressive osteoarthritis, are the hallmark of MLIII, necessitating surgical orthopaedic interventions early in life. Future therapies for this disease should focus on improving cartilage and bone quality, preventing skeletal complications and improving mobility.
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Affiliation(s)
- Esmee Oussoren
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - David van Eerd
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Elaine Murphy
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Robin Lachmann
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Jan C. van der Meijden
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - Lies H. Hoefsloot
- Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Rob Verdijk
- Department of Pathology, Erasmus MC, Rotterdam, The Netherlands
| | - George J. G. Ruijter
- Department of Clinical Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Mario Maas
- Department of Radiology and Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Carla E. M. Hollak
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Janneke G. Langendonk
- Department of Internal Medicine, Center for Lysosomal and Metabolic Diseases, Erasmus MC, Rotterdam, The Netherlands
| | - Ans T. van der Ploeg
- Department of Pediatrics, Center for Lysosomal and Metabolic Diseases, Erasmus MC—Sophia Children’s Hospital, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands
| | - Mirjam Langeveld
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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12
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Kondo Y, Fu J, Wang H, Hoover C, McDaniel JM, Steet R, Patra D, Song J, Pollard L, Cathey S, Yago T, Wiley G, Macwana S, Guthridge J, McGee S, Li S, Griffin C, Furukawa K, James JA, Ruan C, McEver RP, Wierenga KJ, Gaffney PM, Xia L. Site-1 protease deficiency causes human skeletal dysplasia due to defective inter-organelle protein trafficking. JCI Insight 2018; 3:121596. [PMID: 30046013 PMCID: PMC6124414 DOI: 10.1172/jci.insight.121596] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/08/2018] [Indexed: 01/18/2023] Open
Abstract
Site-1 protease (S1P), encoded by MBTPS1, is a serine protease in the Golgi. S1P regulates lipogenesis, endoplasmic reticulum (ER) function, and lysosome biogenesis in mice and in cultured cells. However, how S1P differentially regulates these diverse functions in humans has been unclear. In addition, no human disease with S1P deficiency has been identified. Here, we report a pediatric patient with an amorphic and a severely hypomorphic mutation in MBTPS1. The unique combination of these mutations results in a frequency of functional MBTPS1 transcripts of approximately 1%, a finding that is associated with skeletal dysplasia and elevated blood lysosomal enzymes. We found that the residually expressed S1P is sufficient for lipid homeostasis but not for ER and lysosomal functions, especially in chondrocytes. The defective S1P function specifically impairs activation of the ER stress transducer BBF2H7, leading to ER retention of collagen in chondrocytes. S1P deficiency also causes abnormal secretion of lysosomal enzymes due to partial impairment of mannose-6-phosphate-dependent delivery to lysosomes. Collectively, these abnormalities lead to apoptosis of chondrocytes and lysosomal enzyme-mediated degradation of the bone matrix. Correction of an MBTPS1 variant or reduction of ER stress mitigated collagen-trafficking defects. These results define a new congenital human skeletal disorder and, more importantly, reveal that S1P is particularly required for skeletal development in humans. Our findings may also lead to new therapies for other genetic skeletal diseases, as ER dysfunction is common in these disorders.
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Affiliation(s)
- Yuji Kondo
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Jianxin Fu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.,Jiangsu Institute of Hematology, MOH Key Laboratory of Thrombosis and Hemostasis, Collaborative Innovation Center of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | | | - Christopher Hoover
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.,Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - J Michael McDaniel
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Richard Steet
- Complex Carbohydrate Research Center, University of Georgia, Georgia, Athens, USA
| | - Debabrata Patra
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jianhua Song
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Laura Pollard
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Sara Cathey
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Tadayuki Yago
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Graham Wiley
- Division of Genomics and Data Sciences, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Susan Macwana
- Division of Genomics and Data Sciences, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Joel Guthridge
- Division of Genomics and Data Sciences, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Samuel McGee
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | | | - Courtney Griffin
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Koichi Furukawa
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Judith A James
- Division of Genomics and Data Sciences, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Changgeng Ruan
- Jiangsu Institute of Hematology, MOH Key Laboratory of Thrombosis and Hemostasis, Collaborative Innovation Center of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Rodger P McEver
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.,Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | | | - Patrick M Gaffney
- Division of Genomics and Data Sciences, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Lijun Xia
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.,Jiangsu Institute of Hematology, MOH Key Laboratory of Thrombosis and Hemostasis, Collaborative Innovation Center of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, China.,Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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13
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Kazemi N, Estiar MA, Fazilaty H, Sakhinia E. Variants in GNPTAB, GNPTG and NAGPA genes are associated with stutterers. Gene 2017; 647:93-100. [PMID: 29289611 DOI: 10.1016/j.gene.2017.12.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/19/2017] [Accepted: 12/27/2017] [Indexed: 12/20/2022]
Abstract
Non-syndromic stuttering is a neurodevelopmental disorder characterized by disruptions in normal flow of speech in the form of repetition, prolongation and involuntary halts. Previously, mutations with more severe effects on GNPTAB and GNPTG have been reported to cause Mucolipidosisll (ML-ll) and Mucolipidosislll (ML-lll), two lysosomal storage disorders with multiple pathologies. We used homozygosity mapping and Sanger sequencing to investigate variants of the three genes in 25 Iranian families with at least two first degree related non-syndromic stutterers. Bioinformatic evaluation and Segregation analysis of the found variants helped us define probable consequences. We also compared our findings with those related to Mucolipidosis. 14 variations were found in the three genes 3 of which, including a novel variant within intronic region of GNPTG and a heterozygous 2-bp deletion in coding region of GNPTAB, co-segregated with stuttering in the families they were found. Bioinformatics analysis predicted all three variants causing deleterious effects on gene functioning. Our findings support the role of these three variants in non-syndromic stuttering. This finding may challenge the current belief that variations causing stuttering are at different sites and have less severe consequences than genetic changes that cause ML-ll and ML-lll.
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Affiliation(s)
- Nima Kazemi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Division of Medical Genetics, Department of Clinical Biochemistry, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mehrdad Asghari Estiar
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Fazilaty
- Developmental Neurobiology, Instituto de Neurociencias UMH-SIC, Alicante, Spain
| | - Ebrahim Sakhinia
- Connective Tissue Research Center, Department of Medical Genetics, Faculty of Medicine and Tabriz Genetic Analysis Centre (TGAC), Tabriz University of Medical Sciences, Tabriz, Iran.
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14
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Tüysüz B, Kasapçopur Ö, Alkaya DU, Şahin S, Sözeri B, Yeşil G. Mucolipidosis type III gamma: Three novel mutation and genotype-phenotype study in eleven patients. Gene 2017; 642:398-407. [PMID: 29170090 DOI: 10.1016/j.gene.2017.11.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/07/2017] [Accepted: 11/17/2017] [Indexed: 11/18/2022]
Abstract
Mucolipidosis type III gamma (MLIII gamma) is a lysosomal storage disease characterized by joint stiffness, mild coarse face and corneal clouding, which becomes recognizable usually in childhood. Biallelic mutations in the GNPTG gene, which encode the γ subunit of the N-acetylglucosamine-1-phosphotransferase enzyme, are the underlying cause of MLIII gamma. The aim of this study is to evaluate the longitudinal findings and genotype of eleven patients from eight families with MLIII gamma and to establish a genotype-phenotype correlation. The most frequently observed initial finding was stiffness of finger joints, which detected in patients between 18month-olds and five year-olds. However, in four patients presented here, initial finding was knee pain or waddling gait, which started between six-16years of age. All patients also had variable degrees of stiffness on large joints. The longest follow up period was 16years while the shortest was three years and six months. We observed that the patients who had an early onset disease and severe joint stiffness had also rapidly progressive joint involvement mostly localized in hands, shoulders, and hip. However; the patients with late onset and/or mild joint stiffness experienced slowly progressive symptoms. Most patients dropped in their growth curve in time and the ones who were severely affected reached the final height below the third centile. Seven disease-causing mutations, three of them novel, were detected in GNPTG gene. According to our clinical observations c.493_494insC and c.283_284insC mutations lead to a severe phenotype and c.196C>T, c.347_349del, c.652_655delTACT and c.445delG/c.367A>G mutations seemed to generate a milder phenotype.
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Affiliation(s)
- Beyhan Tüysüz
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey.
| | - Özgür Kasapçopur
- Department of Pediatric Rheumatology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Dilek Uludağ Alkaya
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Sezgin Şahin
- Department of Pediatric Rheumatology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Betül Sözeri
- Department of Pediatric Rheumatology, Ege University Medical School, Izmir, Turkey
| | - Gözde Yeşil
- Department of Medical Genetics, BezmialemVakif University, Istanbul, Turkey
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15
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Enigmatic in vivo GlcNAc-1-phosphotransferase (GNPTG) transcript correction to wild type in two mucolipidosis III gamma siblings homozygous for nonsense mutations. J Hum Genet 2016; 61:555-60. [PMID: 26935170 DOI: 10.1038/jhg.2016.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 12/25/2022]
Abstract
Mucolipidosis (ML) III gamma is a rare autosomal-recessive disorder caused by pathogenic mutations in the GNPTG gene. GNPTG encodes the γ-subunit of GlcNAc-1-phosphotransferase that catalyzes mannose 6-phosphate targeting signal synthesis on soluble lysosomal enzymes. ML III gamma patients are characterized by missorting of lysosomal enzymes. In this report, we describe the probable occurrence of mRNA editing in two ML III gamma patients. Patients A and B (siblings) presented at the adult age with a typical clinical picture of ML III gamma, mainly compromising bone and joints, and high levels of lysosomal enzymes in plasma and low levels in fibroblasts. Both were found to be homozygous for c.-112C>G and c.328G>T (p.Glu110Ter) mutations in genomic DNA (gDNA) analysis of GNPTG. Analysis of complementary DNA (cDNA), however, showed normal genotypes for both patients. Low GNPTG mRNA expression was observed in both patients. The mRNA editing can explain the differences found in patients A and B regarding gDNA and cDNA analysis, and the mild clinical phenotype associated with homozygosity for a nonsense mutation. Our results suggest that mRNA editing can be more frequent than expected in monogenic disorders and that GNPTG analysis should be performed on gDNA.
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16
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Tüysüz B, Ercan-Sencicek AG, Canpolat N, Koparır A, Yılmaz S, Kılıçaslan I, Gülez B, Bilguvar K, Günel M. Renal involvement in patients with mucolipidosis IIIalpha/beta: Causal relation or co-occurrence? Am J Med Genet A 2016; 170A:1187-95. [PMID: 26749367 DOI: 10.1002/ajmg.a.37543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 12/21/2015] [Indexed: 11/07/2022]
Abstract
Mucolipidosis IIIalpha/beta (MLIIIalpha/beta) is a rare lysosomal storage disorder characterized by childhood onset of flexion contractures of fingers, joint stiffness in the shoulders, hips, and knees, and mild short stature. Recessive mutations in the GNPTAB gene have been associated with MLIIIalpha/beta. We present five children aged 9-16 years from a large kindred family whose serum activities of several lysosomal enzymes were significantly elevated. Whole exome sequencing followed by confirmation by Sanger sequencing identified a novel homozygous missense mutation (c.22 A > G; p.R8G) in the GNPTAB gene in all affected subjects. The five patients initially presented with flexion contractures of fingers followed by stiffnes of large joints. Only two affected boys also had a nephrotic-range proteinuria. Renal biopsy showed focal segmental glomerulosclerosis and foamy appearance of glomerular visceral epithelial cells which were compatible with storage disease. No other known causes of proteinuria could be detected by both laboratory and biopsy findings. There was no known family history of hereditary kidney disease, and healthy siblings and parents had normal renal function and urinalysis. These findings suggest that the renal involvement probably due to MLIIIalpha/beta, although it can still be present by coincidence in the two affected patients.
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Affiliation(s)
- Beyhan Tüysüz
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | | | - Nur Canpolat
- Department of Pediatric Nephrology, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Asuman Koparır
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University, Istanbul, Turkey
| | - Saliha Yılmaz
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Işın Kılıçaslan
- Department of Pathology, Istanbul Medical School, Istanbul University, Istanbul, Turkey
| | - Burcu Gülez
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Kaya Bilguvar
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
| | - Murat Günel
- Department of Neurosurgery, Program on Neurogenetics, Yale School of Medicine, New Haven, Connecticut
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17
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Qian Y, van Meel E, Flanagan-Steet H, Yox A, Steet R, Kornfeld S. Analysis of mucolipidosis II/III GNPTAB missense mutations identifies domains of UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase involved in catalytic function and lysosomal enzyme recognition. J Biol Chem 2014; 290:3045-56. [PMID: 25505245 DOI: 10.1074/jbc.m114.612507] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase tags newly synthesized lysosomal enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endolysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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Affiliation(s)
- Yi Qian
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Eline van Meel
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | | | - Alex Yox
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Richard Steet
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Stuart Kornfeld
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
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18
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Paton L, Bitoun E, Kenyon J, Priestman DA, Oliver PL, Edwards B, Platt FM, Davies KE. A novel mouse model of a patient mucolipidosis II mutation recapitulates disease pathology. J Biol Chem 2014; 289:26709-26721. [PMID: 25107912 PMCID: PMC4175314 DOI: 10.1074/jbc.m114.586156] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mucolipidosis II (MLII) is a lysosomal storage disorder caused by loss of N-acetylglucosamine-1-phosphotransferase, which tags lysosomal enzymes with a mannose 6-phosphate marker for transport to the lysosome. In MLII, the loss of this marker leads to deficiency of multiple enzymes and non-enzymatic proteins in the lysosome, leading to the storage of multiple substrates. Here we present a novel mouse model of MLII homozygous for a patient mutation in the GNPTAB gene. Whereas the current gene knock-out mouse model of MLII lacks some of the characteristic features of the human disease, our novel mouse model more fully recapitulates the human pathology, showing growth retardation, skeletal and facial abnormalities, increased circulating lysosomal enzymatic activities, intracellular lysosomal storage, and reduced life span. Importantly, MLII behavioral deficits are characterized for the first time, including impaired motor function and psychomotor retardation. Histological analysis of the brain revealed progressive neurodegeneration in the cerebellum with severe Purkinje cell loss as the underlying cause of the ataxic gait. In addition, based on the loss of Npc2 (Niemann-Pick type C 2) protein expression in the brain, the mice were treated with 2-hydroxypropyl-β-cyclodextrin, a drug previously reported to rescue Purkinje cell death in a mouse model of Niemann-Pick type C disease. No improvement in brain pathology was observed. This indicates that cerebellar degeneration is not primarily triggered by loss of Npc2 function. This study emphasizes the value of modeling MLII patient mutations to generate clinically relevant mouse mutants to elucidate the pathogenic molecular pathways of MLII and address their amenability to therapy.
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Affiliation(s)
- Leigh Paton
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Emmanuelle Bitoun
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Janet Kenyon
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and
| | - David A Priestman
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Peter L Oliver
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Benjamin Edwards
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Kay E Davies
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, South Parks Road, Oxford OX1 3PT, United Kingdom and.
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19
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Wen CC, Weng CY, Lin MJ, Chu SY. Biopsychosocial issues of a patient with mucolipidosis type II. Tzu Chi Med J 2014. [DOI: 10.1016/j.tcmj.2013.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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20
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De Pace R, Coutinho MF, Koch-Nolte F, Haag F, Prata MJ, Alves S, Braulke T, Pohl S. Mucolipidosis II-related mutations inhibit the exit from the endoplasmic reticulum and proteolytic cleavage of GlcNAc-1-phosphotransferase precursor protein (GNPTAB). Hum Mutat 2014; 35:368-76. [PMID: 24375680 DOI: 10.1002/humu.22502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/13/2013] [Indexed: 01/12/2023]
Abstract
Mucolipidosis (ML) II and MLIII alpha/beta are two pediatric lysosomal storage disorders caused by mutations in the GNPTAB gene, which encodes an α/β-subunit precursor protein of GlcNAc-1-phosphotransferase. Considerable variations in the onset and severity of the clinical phenotype in these diseases are observed. We report here on expression studies of two missense mutations c.242G>T (p.Trp81Leu) and c.2956C>T (p.Arg986Cys) and two frameshift mutations c.3503_3504delTC (p.Leu1168GlnfsX5) and c.3145insC (p.Gly1049ArgfsX16) present in severely affected MLII patients, as well as two missense mutations c.1196C>T (p.Ser399Phe) and c.3707A>T (p.Lys1236Met) reported in more mild affected individuals. We generated a novel α-subunit-specific monoclonal antibody, allowing the analysis of the expression, subcellular localization, and proteolytic activation of wild-type and mutant α/β-subunit precursor proteins by Western blotting and immunofluorescence microscopy. In general, we found that both missense and frameshift mutations that are associated with a severe clinical phenotype cause retention of the encoded protein in the endoplasmic reticulum and failure to cleave the α/β-subunit precursor protein are associated with a severe clinical phenotype with the exception of p.Ser399Phe found in MLIII alpha/beta. Our data provide new insights into structural requirements for localization and activity of GlcNAc-1-phosphotransferase that may help to explain the clinical phenotype of MLII patients.
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Affiliation(s)
- Raffaella De Pace
- Section Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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21
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Kollmann K, Damme M, Markmann S, Morelle W, Schweizer M, Hermans-Borgmeyer I, Röchert AK, Pohl S, Lübke T, Michalski JC, Käkelä R, Walkley SU, Braulke T. Lysosomal dysfunction causes neurodegeneration in mucolipidosis II 'knock-in' mice. ACTA ACUST UNITED AC 2012; 135:2661-75. [PMID: 22961545 DOI: 10.1093/brain/aws209] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Mucolipidosis II is a neurometabolic lysosomal trafficking disorder of infancy caused by loss of mannose 6-phosphate targeting signals on lysosomal proteins, leading to lysosomal dysfunction and accumulation of non-degraded material. However, the identity of storage material and mechanisms of neurodegeneration in mucolipidosis II are unknown. We have generated 'knock-in' mice with a common mucolipidosis II patient mutation that show growth retardation, progressive brain atrophy, skeletal abnormalities, elevated lysosomal enzyme activities in serum, lysosomal storage in fibroblasts and brain and premature death, closely mimicking the mucolipidosis II disease in humans. The examination of affected mouse brains at different ages by immunohistochemistry, ultrastructural analysis, immunoblotting and mass spectrometric analyses of glycans and anionic lipids revealed that the expression and proteolytic processing of distinct lysosomal proteins such as α-l-fucosidase, β-hexosaminidase, α-mannosidase or Niemann-Pick C2 protein are more significantly impacted by the loss of mannose 6-phosphate residues than enzymes reaching lysosomes independently of this targeting mechanism. As a consequence, fucosylated N-glycans, GM2 and GM3 gangliosides, cholesterol and bis(monoacylglycero)phosphate accumulate progressively in the brain of mucolipidosis II mice. Prominent astrogliosis and the accumulation of organelles and storage material in focally swollen axons were observed in the cerebellum and were accompanied by a loss of Purkinje cells. Moreover, an increased neuronal level of the microtubule-associated protein 1 light chain 3 and the formation of p62-positive neuronal aggregates indicate an impairment of constitutive autophagy in the mucolipidosis II brain. Our findings demonstrate the essential role of mannose 6-phosphate for selected lysosomal proteins to maintain the capability for degradation of sequestered components in lysosomes and autophagolysosomes and prevent neurodegeneration. These lysosomal proteins might be a potential target for a valid therapeutic approach for mucolipidosis II disease.
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Affiliation(s)
- K Kollmann
- Department of Biochemistry, Children’s Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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Marschner K, Kollmann K, Schweizer M, Braulke T, Pohl S. A key enzyme in the biogenesis of lysosomes is a protease that regulates cholesterol metabolism. Science 2011; 333:87-90. [PMID: 21719679 DOI: 10.1126/science.1205677] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mucolipidosis II is a severe lysosomal storage disorder caused by defects in the α and β subunits of the hexameric N-acetylglucosamine-1-phosphotransferase complex essential for the formation of the mannose 6-phosphate targeting signal on lysosomal enzymes. Cleavage of the membrane-bound α/β-subunit precursor by an unknown protease is required for catalytic activity. Here we found that the α/β-subunit precursor is cleaved by the site-1 protease (S1P) that activates sterol regulatory element-binding proteins in response to cholesterol deprivation. S1P-deficient cells failed to activate the α/β-subunit precursor and exhibited a mucolipidosis II-like phenotype. Thus, S1P functions in the biogenesis of lysosomes, and lipid-independent phenotypes of S1P deficiency may be caused by lysosomal dysfunction.
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Affiliation(s)
- Katrin Marschner
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Pohl S, Tiede S, Marschner K, Encarnação M, Castrichini M, Kollmann K, Muschol N, Ullrich K, Müller-Loennies S, Braulke T. Proteolytic processing of the gamma-subunit is associated with the failure to form GlcNAc-1-phosphotransferase complexes and mannose 6-phosphate residues on lysosomal enzymes in human macrophages. J Biol Chem 2010; 285:23936-44. [PMID: 20489197 DOI: 10.1074/jbc.m110.129684] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GlcNAc-1-phosphotransferase is a Golgi-resident 540-kDa complex of three subunits, alpha(2)beta(2)gamma(2), that catalyze the first step in the formation of the mannose 6-phosphate (M6P) recognition marker on lysosomal enzymes. Anti-M6P antibody analysis shows that human primary macrophages fail to generate M6P residues. Here we have explored the sorting and intracellular targeting of cathepsin D as a model, and the expression of the GlcNAc-1-phosphotransferase complex in macrophages. Newly synthesized cathepsin D is transported to lysosomes in an M6P-independent manner in association with membranes whereas the majority is secreted. Realtime PCR analysis revealed a 3-10-fold higher GlcNAc-1-phosphotransferase subunit mRNA levels in macrophages than in fibroblasts or HeLa cells. At the protein level, the gamma-subunit but not the beta-subunit was found to be proteolytically cleaved into three fragments which form irregular 97-kDa disulfide-linked oligomers in macrophages. Size exclusion chromatography showed that the gamma-subunit fragments lost the capability to assemble with other GlcNAc-1-phosphotransferase subunits to higher molecular complexes. These findings demonstrate that proteolytic processing of the gamma-subunit represents a novel mechanism to regulate GlcNAc-1-phosphotransferase activity and the subsequent sorting of lysosomal enzymes.
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Affiliation(s)
- Sandra Pohl
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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24
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Kang C, Riazuddin S, Mundorff J, Krasnewich D, Friedman P, Mullikin JC, Drayna D. Mutations in the lysosomal enzyme-targeting pathway and persistent stuttering. N Engl J Med 2010; 362:677-85. [PMID: 20147709 PMCID: PMC2936507 DOI: 10.1056/nejmoa0902630] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Stuttering is a disorder of unknown cause characterized by repetitions, prolongations, and interruptions in the flow of speech. Genetic factors have been implicated in this disorder, and previous studies of stuttering have identified linkage to markers on chromosome 12. METHODS We analyzed the chromosome 12q23.3 genomic region in consanguineous Pakistani families, some members of which had nonsyndromic stuttering and in unrelated case and control subjects from Pakistan and North America. RESULTS We identified a missense mutation in the N-acetylglucosamine-1-phosphate transferase gene (GNPTAB), which encodes the alpha and beta catalytic subunits of GlcNAc-phosphotransferase (GNPT [EC 2.7.8.15]), that was associated with stuttering in a large, consanguineous Pakistani family. This mutation occurred in the affected members of approximately 10% of Pakistani families studied, but it occurred only once in 192 chromosomes from unaffected, unrelated Pakistani control subjects and was not observed in 552 chromosomes from unaffected, unrelated North American control subjects. This and three other mutations in GNPTAB occurred in unrelated subjects with stuttering but not in control subjects. We also identified three mutations in the GNPTG gene, which encodes the gamma subunit of GNPT, in affected subjects of Asian and European descent but not in control subjects. Furthermore, we identified three mutations in the NAGPA gene, which encodes the so-called uncovering enzyme, in other affected subjects but not in control subjects. These genes encode enzymes that generate the mannose-6-phosphate signal, which directs a diverse group of hydrolases to the lysosome. Deficits in this system are associated with the mucolipidoses, rare lysosomal storage disorders that are most commonly associated with bone, connective tissue, and neurologic symptoms. CONCLUSIONS Susceptibility to nonsyndromic stuttering is associated with variations in genes governing lysosomal metabolism.
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Affiliation(s)
- Changsoo Kang
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
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Pohl S, Encarnacão M, Castrichini M, Müller-Loennies S, Muschol N, Braulke T. Loss of N-acetylglucosamine-1-phosphotransferase gamma subunit due to intronic mutation in GNPTG causes mucolipidosis type III gamma: Implications for molecular and cellular diagnostics. Am J Med Genet A 2009; 152A:124-32. [DOI: 10.1002/ajmg.a.33170] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Otomo T, Higaki K, Nanba E, Ozono K, Sakai N. Inhibition of autophagosome formation restores mitochondrial function in mucolipidosis II and III skin fibroblasts. Mol Genet Metab 2009; 98:393-9. [PMID: 19656701 DOI: 10.1016/j.ymgme.2009.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 07/01/2009] [Indexed: 01/07/2023]
Abstract
Mucolipidosis II and III are progressive lysosomal storage disorders caused by a deficiency of N-acetylglucosamine-1-phosphotransferase, leading to massive accumulation of undigested substrates in lysosomes (inclusion bodies) in skin fibroblast. In this study, we demonstrated accumulation of autolysosomes and increased levels of p62 and ubiquitin proteins in cultured fibroblasts. These autophagic elevations were milder in mucolipidosis III compared with mucolipidosis II. Mitochondrial structure was fragmented and activity was impaired in the affected cells, and 3-methyladenine, an inhibitor of autophagosome formation, restored these. These results show for the first time autophagic and mitochondrial dysfunctions in this disorder.
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Affiliation(s)
- Takanobu Otomo
- Department of Pediatrics (D-5), Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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Kollmann K, Pohl S, Marschner K, Encarnação M, Sakwa I, Tiede S, Poorthuis BJ, Lübke T, Müller-Loennies S, Storch S, Braulke T. Mannose phosphorylation in health and disease. Eur J Cell Biol 2009; 89:117-23. [PMID: 19945768 DOI: 10.1016/j.ejcb.2009.10.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Lysosomal hydrolases catalyze the degradation of a variety of macromolecules including proteins, carbohydrates, nucleic acids and lipids. The biogenesis of lysosomes or lysosome-related organelles requires a continuous substitution of soluble acid hydrolases and lysosomal membrane proteins. The targeting of lysosomal hydrolases depends on mannose 6-phosphate residues (M6P) that are recognized by specific receptors mediating their transport to an endosomal/prelysosomal compartment. The key role in the formation of M6P residues plays the GlcNAc-1-phosphotransferase localized in the Golgi apparatus. Two genes have been identified recently encoding the type III alpha/beta-subunit precursor membrane protein and the soluble gamma-subunit of GlcNAc-1-phosphotransferase. Mutations in these genes result in two severe diseases, mucolipidosis type II (MLII) and III (MLIII), biochemically characterized by the missorting of multiple lysosomal hydrolases due to impaired formation of the M6P recognition marker, and general lysosomal dysfunction. This review gives an update on structural properties, localization and functions of the GlcNAc-1-phosphotransferase subunits and improvements of pre- and postnatal diagnosis of ML patients. Further, the generation of recombinant single-chain antibody fragments against M6P residues and of new mouse models of MLII and MLIII will have considerable impact to provide deeper insight into the cell biology of lysosomal dysfunctions and the pathomechanisms underlying these lysosomal disorders.
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Affiliation(s)
- Katrin Kollmann
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Research Campus, Martinistrasse 52, 20246 Hamburg, Germany
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Cathey SS, Leroy JG, Wood T, Eaves K, Simensen RJ, Kudo M, Stevenson RE, Friez MJ. Phenotype and genotype in mucolipidoses II and III alpha/beta: a study of 61 probands. J Med Genet 2009; 47:38-48. [PMID: 19617216 DOI: 10.1136/jmg.2009.067736] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Mucolipidoses II and III alpha/beta (ML II and ML III) are lysosomal disorders in which the essential mannose 6-phosphate recognition marker is not synthesised on to lysosomal hydrolases and other glycoproteins. The disorders are caused by mutations in GNPTAB, which encodes two of three subunits of the heterohexameric enzyme, N-acetylglucosamine-1-phosphotransferase. OBJECTIVES Clinical, biochemical and molecular findings in 61 probands (63 patients) are presented to provide a broad perspective of these mucolipidoses. METHODS GNPTAB was sequenced in all probands and/or parents. The activity of several lysosomal enzymes was measured in plasma, and GlcNAc-1-phosphotransferase was assayed in leucocytes. Thirty-six patients were studied in detail, allowing extensive clinical data to be abstracted. RESULTS ML II correlates with near-total absence of phosphotransferase activity resulting from homozygosity or compound heterozygosity for frameshift or nonsense mutations. Craniofacial and orthopaedic manifestations are evident at birth, skeletal findings become more obvious within the first year, and growth is severely impaired. Speech, ambulation and cognitive function are impaired. ML III retains a low level of phosphotransferase activity because of at least one missense or splice site mutation. The phenotype is milder, with minimal delays in milestones, the appearance of facial coarsening by early school age, and slowing of growth after the age of 4 years. CONCLUSIONS Fifty-one pathogenic changes in GNPTAB are presented, including 42 novel mutations. Ample clinical information improves criteria for delineation of ML II and ML III. Phenotype-genotype correlations suggested in more general terms in earlier reports on smaller groups of patients are specified and extended.
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Affiliation(s)
- S S Cathey
- Greenwood Genetic Center, Charleston Office, Montague Oaks Office Park, N Charleston, SC 29418, USA.
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Encarnação M, Lacerda L, Costa R, Prata MJ, Coutinho MF, Ribeiro H, Lopes L, Pineda M, Ignatius J, Galvez H, Mustonen A, Vieira P, Lima MR, Alves S. Molecular analysis of theGNPTABandGNPTGgenes in 13 patients with mucolipidosis type II or type III - identification of eight novel mutations. Clin Genet 2009; 76:76-84. [PMID: 19659762 DOI: 10.1111/j.1399-0004.2009.01185.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M Encarnação
- National Health Institute Dr Ricardo Jorge, Center of Medical Genetics Dr Jacinto Magalhães, 4099-028 Porto, Portugal
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30
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Dierks T, Schlotawa L, Frese MA, Radhakrishnan K, von Figura K, Schmidt B. Molecular basis of multiple sulfatase deficiency, mucolipidosis II/III and Niemann–Pick C1 disease — Lysosomal storage disorders caused by defects of non-lysosomal proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:710-25. [DOI: 10.1016/j.bbamcr.2008.11.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 11/11/2008] [Accepted: 11/24/2008] [Indexed: 12/11/2022]
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Braulke T, Pohl S, Storch S. Molecular analysis of the GlcNac-1-phosphotransferase. J Inherit Metab Dis 2008; 31:253-7. [PMID: 18425436 DOI: 10.1007/s10545-008-0862-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 01/14/2008] [Accepted: 01/16/2008] [Indexed: 11/28/2022]
Abstract
Modification of the carbohydrate chains of soluble lysosomal enzymes with mannose 6-phosphate residues is a prerequisite for their mannose 6-phosphate receptor-dependent transport to lysosomes. GlcNac-1-phosphotransferase localized in the Golgi apparatus represents a hexameric alpha(2)beta(2)gamma(2) subunit complex and plays a key role in the formation of the mannose 6-phosphate recognition marker. Defects in the GlcNac-1-phosphotransferase complex cause two diseases, mucolipidosis type II and III, which are characterized by missorting and cellular loss of lysosomal enzymes, and lysosomal accumulation of storage material. The recent identification of two genes, GNPTAB and GNPTG, encoding the three subunits of GlcNac-1-phosphotransferase leads to an improvement of both pre- and postnatal diagnosis of affected individuals, and permits the analysis of structural requirements for efficient formation of mannose 6-phosphate residues on lysosomal enzymes. The alpha/beta subunits precursor matures by proteolytic cleavage and contains the catalytic activity as well as the capability to recognize lysosomal enzymes. The role of the gamma-subunits for activity, stability and oligomerization of the GlcNac-1-phosphotransferase subunits is still unclear.
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Affiliation(s)
- T Braulke
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Tappino B, Regis S, Corsolini F, Filocamo M. An Alu insertion in compound heterozygosity with a microduplication in GNPTAB gene underlies Mucolipidosis II. Mol Genet Metab 2008; 93:129-33. [PMID: 17964840 DOI: 10.1016/j.ymgme.2007.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Revised: 09/17/2007] [Accepted: 09/17/2007] [Indexed: 11/22/2022]
Abstract
Mucolipidosis type II (ML II) is a fatal, autosomal recessive, lysosomal storage disorder characterized by severe clinical and radiologic features. ML II results from mutations in alpha and beta subunits, encoded by the GlcNAc-1-phosphotransferase gene (GNPTAB). Most of the 40 different GNPTAB mutations reported so far are insertions and deletions predicting diverse types of aberrant proteins. Alu mobile elements have however never been involved in these events up to now. The Italian ML II patient of our study showed an Alu retrotrasposition in GNPTAB exon 5. The Alu insertion mutation (NM_024312.3:c.555_556insHSU14569) generated a transcript with a skipping of the target exon 5 and a frameshift p.S122fs, causing a premature translation termination codon at position 123. This insertion mutation was found in compound heterozygosity with the frameshift p.S887KfsX33, resulting from a new mono-nucleotide duplication (c.2659dupA) that occurred in GNPTAB exon 13. A possible involvement of cis-splicing elements having an exonic location, such as exon enhancers (ESEs), is discussed as mechanism that led to the production of the aberrant mRNA splicing.
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Affiliation(s)
- B Tappino
- Laboratorio Diagnosi Pre-Postnatale Malattie Metaboliche, IRCCS G. Gaslini, L.go G. Gaslini, 16147 Genoa, Italy
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Plante M, Claveau S, Lepage P, Lavoie ÈM, Brunet S, Roquis D, Morin C, Vézina H, Laprise C. Mucolipidosis II: a single causal mutation in the N-acetylglucosamine-1-phosphotransferase gene (GNPTAB) in a French Canadian founder population. Clin Genet 2008; 73:236-44. [DOI: 10.1111/j.1399-0004.2007.00954.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lee WS, Payne BJ, Gelfman CM, Vogel P, Kornfeld S. Murine UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase lacking the gamma-subunit retains substantial activity toward acid hydrolases. J Biol Chem 2007; 282:27198-27203. [PMID: 17652091 DOI: 10.1074/jbc.m704067200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase) mediates the first step in the synthesis of the mannose 6-phosphate recognition marker on acid hydrolases. The transferase exists as an alpha(2)beta(2)gamma(2) hexameric complex with the alpha- and beta-subunits derived from a single precursor molecule. The catalytic function of the transferase is attributed to the alpha- and beta-subunits, whereas the gamma-subunit is believed to be involved in the recognition of a conformation-dependent protein determinant common to acid hydrolases. Using knock-out mice with mutations in either the alpha/beta gene or the gamma gene, we show that disruption of the alpha/beta gene completely abolishes phosphorylation of high mannose oligosaccharides on acid hydrolases whereas knock-out of the gamma gene results in only a partial loss of phosphorylation. These findings demonstrate that the alpha/beta-subunits, in addition to their catalytic function, have some ability to recognize acid hydrolases as specific substrates. This process is enhanced by the gamma-subunit.
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Affiliation(s)
- Wang-Sik Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | | | | | - Peter Vogel
- Lexicon Pharmaceuticals, Inc., The Woodlands, Texas 77381
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and.
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Ho CYS, Tang NLS, Yeung AKY, Lau AKC, Hui J, Lo AWI. Abnormal expressions of the subunits of the UDP-N-acetylglucosamine: lysosomal enzyme, N-acetylglucosamine-1-phosphotransferase, result in the formation of cytoplasmic vacuoles resembling those of the I-cells. J Mol Med (Berl) 2006; 85:351-60. [PMID: 17160405 DOI: 10.1007/s00109-006-0128-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 09/06/2006] [Accepted: 10/04/2006] [Indexed: 10/23/2022]
Abstract
Defects in the multimeric enzyme, UDP-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GNPT), result in the diseases of mucolipidosis (ML). This enzyme generates the mannose 6-phosphate residues on newly synthesized lysosomal enzymes for the efficient receptor-mediated transport to lysosomes. The enzyme contains alpha/beta and gamma subunits. Mutations in the alpha/beta subunit result in the classical ML II and IIIA, while defects in the gamma subunit results in the clinically milder ML IIIC. I-cells, a distinct histological feature characterized by the presence of abnormal cytoplasmic vacuoles, are detected in many cell types, most noticeably, in ML II patients. In this study, we investigated the interactions of the alpha/beta and gamma subunits in the pathogenesis of I-cells. We noted low and deranged alpha/beta subunit expressions in human mucolipidosis cell lines. Unexpectedly, high gamma subunit expressions were also observed. In normal mouse fibroblasts, when alpha/beta subunit was suppressed, abnormal cytoplasmic vacuoles were induced, and up-regulation of the gamma subunit was also observed. On the other hand, suppressing the gamma subunit resulted in biphasic responses of the alpha/beta subunit, while abnormal cytoplasmic vacuoles were not formed, regardless of the expression levels of the alpha/beta subunit. Our data suggest reciprocal feedback mechanisms between alpha/beta and the gamma subunits. A fine balance of the expressions of these subunits may play an important role in the formation of I-cells in this group of lysosomal storage disorders.
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Affiliation(s)
- Cecilia Y S Ho
- Anatomical and Cellular Pathology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR
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Bargal R, Zeigler M, Abu-Libdeh B, Zuri V, Mandel H, Ben Neriah Z, Stewart F, Elcioglu N, Hindi T, Le Merrer M, Bach G, Raas-Rothschild A. When Mucolipidosis III meets Mucolipidosis II: GNPTA gene mutations in 24 patients. Mol Genet Metab 2006; 88:359-63. [PMID: 16630736 DOI: 10.1016/j.ymgme.2006.03.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 03/06/2006] [Accepted: 03/08/2006] [Indexed: 11/20/2022]
Abstract
Mucolipidosis II (ML II) and Mucolipidosis type III (ML III) are autosomal recessive disorders of lysosomal hydrolases trafficking due to the deficiency of the multimeric enzyme, UDP-N-acetylglucosamine-1-phosphotransferase. The alpha/beta subunits encoded by the GNPTA gene is the catalytic subunit of the enzyme while the gamma recognition subunit is encoded by the GNPTAG gene. We report the molecular analysis of GNPTA in 21 families with ML II and 3 families with ML III. The ML II mutant genotypes included three splice-site mutations [IVS1-2A>G; IVS17+1G>A; IVS18+1G>A] in seven Palestinian, Israeli Arab-Muslims, and Turkish patients; a two base pair deletion [c.3503_4delTC] [corrected] in 11 patients from Israel, Turkey, and Ireland; two nonsense mutations [c.2533C>T (Q845X); c.3613C>T (R1205X)], in a Turkish and an Arab-Muslim patient from the Nablus area, respectively, and an insertion mutation [c.2916insT] in a patient from Nablus. The ML III mutant genotypes included a splice-site mutation [IVS17+6T>G] in two patients from Irish/Scottish origin who were compound heterozygous for a nonsense mutation [c.3565C>T (R1189X)] and the deletion mutation [c.3503_4delTC] [corrected] respectively. The third ML III patient from France was compound heterozygous for a missense mutation [c.1196C>T] and the same deletion [c.3503_4delTC] [corrected] found homozygous in 11 ML II patients. The 21 ML II patients were homozygous while the three ML III patients were compound heterozygous for mutations in GNPTA. The results of this study confirm that ML II or ML III phenotype is not due to the localization of the mutations, but rather to the severity of the mutations, ML II and ML III might be allelic, and ML III is genetically heterogeneous. We suggest that the diseases due to mutations in GNPTA represent a clinical continuum between ML III and ML II, and the classification of these diseases should be based on the age of onset, clinical symptoms, and severity.
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Affiliation(s)
- Ruth Bargal
- Department of Human Genetics, Hadassah Hebrew University Medical Center, Jerusalem, Israel
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