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Qiao W, Richards CM, Jabs S. LYSET/TMEM251- a novel key component of the mannose 6-phosphate pathway. Autophagy 2023; 19:2143-2145. [PMID: 36633450 PMCID: PMC10283412 DOI: 10.1080/15548627.2023.2167376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/06/2023] [Accepted: 01/06/2023] [Indexed: 01/13/2023] Open
Abstract
Degradation of macromolecules delivered to lysosomes by processes such as autophagy or endocytosis is crucial for cellular function. Lysosomes require more than 60 soluble hydrolases in order to catabolize such macromolecules. These soluble hydrolases are tagged with mannose6-phosphate (M6P) moieties in sequential reactions by the Golgi-resident GlcNAc-1-phosphotransferase complex and NAGPA/UCE/uncovering enzyme (N-acetylglucosamine-1-phosphodiester alpha-N-acetylglucosaminidase), which allows their delivery to endosomal/lysosomal compartments through trafficking mediated by cation-dependent and -independent mannose 6-phosphate receptors (MPRs). We and others recently identified TMEM251 as a novel regulator of the M6P pathway via independent genome-wide genetic screening strategies. We renamed TMEM251 to LYSET (lysosomal enzyme trafficking factor) to establish nomenclature reflective to this gene's function. LYSET is a Golgi-localized transmembrane protein important for the retention of the GlcNAc-1-phosphotransferase complex in the Golgi-apparatus. The current understanding of LYSET's importance regarding human biology is 3-fold: 1) highly pathogenic viruses that depend on lysosomal hydrolase activity require LYSET for infection. 2) The presence of LYSET is critical for cancer cell proliferation in nutrient-deprived environments in which extracellular proteins must be catabolized. 3) Inherited pathogenic alleles of LYSET can cause a severe inherited disease which resembles GlcNAc-1-phosphotransferase deficiency (i.e., mucolipidosis type II).Abbreviations: GlcNAc-1-PT: GlcNAc-1-phosphotransferase; KO: knockout; LSD: lysosomal storage disorder; LYSET: lysosomal enzyme trafficking factor; M6P: mannose 6-phosphate; MPRs: mannose-6-phosphate receptors, cation-dependent or -independent; MBTPS1/site-1 protease: membrane bound transcription factor peptidase, site 1; MLII: mucolipidosis type II; WT: wild-type.
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Affiliation(s)
- Wenjie Qiao
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Christopher M. Richards
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Sabrina Jabs
- Institute of Clinical Molecular Biology, Christian-Albrechts-University and University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Schleswig-Holstein, Germany
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2
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Gorelik A, Illes K, Bui KH, Nagar B. Structures of the mannose-6-phosphate pathway enzyme, GlcNAc-1-phosphotransferase. Proc Natl Acad Sci U S A 2022; 119:e2203518119. [PMID: 35939698 PMCID: PMC9388126 DOI: 10.1073/pnas.2203518119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
The mannose-6-phosphate (M6P) pathway is responsible for the transport of hydrolytic enzymes to lysosomes. N-acetylglucosamine-1-phosphotransferase (GNPT) catalyzes the first step of tagging these hydrolases with M6P, which when recognized by receptors in the Golgi diverts them to lysosomes. Genetic defects in the GNPT subunits, GNPTAB and GNPTG, cause the lysosomal storage diseases mucolipidosis types II and III. To better understand its function, we determined partial three-dimensional structures of the GNPT complex. The catalytic domain contains a deep cavity for binding of uridine diphosphate-N-acetylglucosamine, and the surrounding residues point to a one-step transfer mechanism. An isolated structure of the gamma subunit of GNPT reveals that it can bind to mannose-containing glycans in different configurations, suggesting that it may play a role in directing glycans into the active site. These findings may facilitate the development of therapies for lysosomal storage diseases.
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Affiliation(s)
- Alexei Gorelik
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Katalin Illes
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Bhushan Nagar
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
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3
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Liu L, Doray B. Elevated mRNA expression and defective processing of cathepsin D in HeLa cells lacking the mannose 6-phosphate pathway. FEBS Open Bio 2021; 11:1695-1703. [PMID: 33932147 PMCID: PMC8167872 DOI: 10.1002/2211-5463.13169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/18/2021] [Accepted: 04/16/2021] [Indexed: 11/30/2022] Open
Abstract
Disruption of the mannose 6‐phosphate (M‐6‐P) pathway in HeLa cells by inactivation of the GNPTAB gene, which encodes the α/β subunits of GlcNAc‐1‐phosphotransferase, results in missorting of newly synthesized lysosomal acid hydrolases to the cell culture media instead of transport to the endolysosomal system. We previously demonstrated that the majority of the lysosomal aspartyl protease, cathepsin D, is secreted in these GNPTAB−/− HeLa cells. However, the intracellular content of cathepsin D in these cells was still greater than that of WT HeLa cells which retained most of the protease, indicating a marked elevation of cathepsin D expression in response to abrogation of the M‐6‐P pathway. Here, we demonstrate that HeLa cells lacking GlcNAc‐1‐phosphotransferase show a fivefold increase in cathepsin D mRNA expression over control cells, accounting for the increase in cathepsin D at the protein level. Further, we show that this increase at the mRNA level occurs independent of the transcription factors TFEB and TFE3. The intracellular cathepsin D can still be trafficked to lysosomes in the absence of the M‐6‐P pathway, but fails to undergo proteolytic processing into the fully mature heavy and light chains. Uptake experiments performed by feeding GNPTAB−/− HeLa cells with various phosphorylated cathepsins reveal that only cathepsin B is capable of partially restoring cleavage, providing evidence for a role for cathepsin B in the proteolytic processing of cathepsin D.
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Affiliation(s)
- Lin Liu
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
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Doğan M, Eröz R, Terali K, Gezdirici A, Bolu S. Clinical, radiological and computational studies on two novel GNPTG variants causing mucolipidosis III gamma phenotypes with varying severity. Mol Biol Rep 2021; 48:1465-1474. [PMID: 33507475 DOI: 10.1007/s11033-021-06158-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
Mucolipidosis III gamma (ML III γ) is a slowly progressive disorder that affects multiple parts of the body such as the skeleton, joints, and connective tissue structures. It is caused by pathogenic variants in the GNPTG gene that provides instructions for producing the γ subunit of GlcNAc-1-phosphotransferase. In this study we aim to characterize clinical findings and biological insights on two novel GNPTG variants causing ML III γ phenotypes with varying severity. We report on two siblings with ML III γ bearing the previously undescribed c.477C > G (p.Y159*) nonsense variant in a homozygous state as well as a patient with ML III γ bearing the novel c.110 + 19_111-17del variant in a homozygous state. These variants were revealed by whole-exome sequencing and Sanger sequencing, respectively. Their parents, who are heterozygotes for the same mutation, are healthy. The clinical and radiographic presentation of ML III γ in our patients who had c.477C > G (p.Y159*) variant is consistent with a relatively severe form of the disease, which is further supported by a working three-dimensional model of the GlcNAc-1-phosphotransferase γ subunit. On the other hand, it is seen that our patient who carries the c.110 + 19_111-17del variant has a milder phenotype. Our findings help broaden the spectrum of GNPTG variants causing ML III γ and offer structural and mechanistic insights into loss of GlcNAc-1-phosphotransferase γ subunit function.
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Affiliation(s)
- Mustafa Doğan
- Department of Medical Genetics, Malatya Turgut Ozal University Training and Research Hospital, Malatya, Turkey.
| | - Recep Eröz
- Department of Medical Genetics, Faculty of Medicine, Düzce University, Düzce, Turkey
| | - Kerem Terali
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Nicosia, Cyprus
- Bioinformatics and Computational Biology Research Group, DESAM Institute, Near East University, Nicosia, Cyprus
| | - Alper Gezdirici
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, 34480, Istanbul, Turkey
| | - Semih Bolu
- Department of Pediatric Endocrinology, Adıyaman Training and Research Hospital, Adıyaman, Turkey
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5
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Lee WS, Jennings BC, Doray B, Kornfeld S. Disease-causing missense mutations within the N-terminal transmembrane domain of GlcNAc-1-phosphotransferase impair endoplasmic reticulum translocation or Golgi retention. Hum Mutat 2020; 41:1321-1328. [PMID: 32220096 DOI: 10.1002/humu.24019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/25/2020] [Accepted: 03/22/2020] [Indexed: 11/10/2022]
Abstract
Transport of newly synthesized lysosomal enzymes to the lysosome requires tagging of these enzymes with the mannose 6-phosphate moiety by UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase), encoded by two genes, GNPTAB and GNPTG. GNPTAB encodes the α and β subunits, which are initially synthesized as a single precursor that is cleaved by Site-1 protease in the Golgi. Mutations in this gene cause the lysosomal storage disorders mucolipidosis II (MLII) and mucolipidosis III αβ (MLIII αβ). Two recent studies have reported the first patient mutations within the N-terminal transmembrane domain (TMD) of the α subunit of GlcNAc-1-phosphotransferase that cause either MLII or MLIII αβ. Here, we demonstrate that two of the MLII missense mutations, c.80T>A (p.Val27Asp) and c.83T>A (p.Val28Asp), prevent the cotranslational insertion of the nascent GlcNAc-1-phosphotransferase polypeptide chain into the endoplasmic reticulum. The remaining four mutations, one of which is associated with MLII, c.100G>C (p.Ala34Pro), and the other three with MLIII αβ, c.70T>G (p.Phe24Val), c.77G>A (p.Gly26Asp), and c.107A>C (p.Glu36Pro), impair retention of the catalytically active enzyme in the Golgi with concomitant mistargeting to endosomes/lysosomes. Our results uncover the basis for the disease phenotypes of these patient mutations and establish the N-terminal TMD of GlcNAc-1-phosphotransferase as an important determinant of Golgi localization.
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Affiliation(s)
- Wang-Sik Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Benjamin C Jennings
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
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6
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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7
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Ho CC, Tsung LLY, Liu KT, Poon WT. GNPTAB c.2404C > T nonsense mutation in a patient with mucolipidosis III alpha/beta: a case report. BMC Med Genet 2018; 19:162. [PMID: 30208878 PMCID: PMC6134758 DOI: 10.1186/s12881-018-0679-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/03/2018] [Indexed: 12/11/2022]
Abstract
Background Mucolipidosis alpha/beta is an inborn error of metabolism characterized by deficiency of GlcNAc-1-phosphotransferase, in which essential alpha/beta subunits are encoded by the GNPTAB gene. The autosomal recessive condition is due to disruptions of hydrolase mannose 6-phosphate marker generation, defective lysosomal targeting and subsequent intracellular accumulation of non-degraded material. Clinical severity depends on residual GlcNAc-1-phosphotransferase activity, which distinguishes between the milder type III disease and the severe, neonatal onset type II disease. Case presentation We report the clinical, biochemical and genetic diagnosis of mucolipidosis III alpha/beta in a two-year-old Chinese boy who initially presented with poor weight gain, microcephaly and increased tone. He was confirmed to harbor the common splice site mutation c.2715 + 1G > A and the nonsense variant c.2404C > T (p.Q802*). Clinically, the patient had multiple phenotypic features typical of mucopolysaccharidosis including joint contractures, coarse facial features, kypho-lordosis, pectus carinatum and umbilical hernia. However, the relatively mild developmental delay compared to severe type I and type II mucopolysaccharidosis and the absence of macrocephaly raised the possibility of the less commonly diagnosed mucolipidosis alpha/beta. Critical roles of lysosomal enzyme activity assay, which showed elevated α-iduronidase, iduronate sulfatase, galactose-6-sulphate sulphatase, arylsulfatase B and α-hexosaminidase activities; and genetic study, which confirmed the parental origin of both mutations, were highlighted. Conclusions The recently reported nonsense variant c.2404C > T in the GNPTAB gene is further recognized and this contributes to the genotype-phenotype spectrum of mucolipidosis alpha/beta. Electronic supplementary material The online version of this article (10.1186/s12881-018-0679-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chi-Chun Ho
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong Special Administrative Region, China
| | - Lilian Li-Yan Tsung
- Department of Paediatrics & Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong Special Administrative Region, China
| | - Kam-Tim Liu
- Department of Paediatrics & Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong Special Administrative Region, China
| | - Wing-Tat Poon
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong Special Administrative Region, China.
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Velho RV, De Pace R, Klünder S, Di Lorenzo G, Schweizer M, Braulke T, Pohl S. Site-1 protease and lysosomal homeostasis. Biochim Biophys Acta Mol Cell Res 2017; 1864:2162-8. [PMID: 28693924 DOI: 10.1016/j.bbamcr.2017.06.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 11/22/2022]
Abstract
The Golgi-resident site-1 protease (S1P) is a key regulator of cholesterol homeostasis and ER stress responses by converting latent transcription factors sterol regulatory element binding proteins (SREPBs) and activating transcription factor 6 (ATF6), as well as viral glycoproteins to their active forms. S1P is also essential for lysosome biogenesis via proteolytic activation of the hexameric GlcNAc-1-phosphotransferase complex required for modification of newly synthesized lysosomal enzymes with the lysosomal targeting signal, mannose 6-phosphate. In the absence of S1P, the catalytically inactive α/β-subunit precursor of GlcNAc-1-phosphotransferase fails to be activated and results in missorting of newly synthesized lysosomal enzymes, and lysosomal accumulation of non-degraded material, which are biochemical features of defective GlcNAc-1-phosphotransferase subunits and the associated pediatric lysosomal diseases mucolipidosis type II and III. The early embryonic death of S1P-deficient mice and the importance of various S1P-regulated biological processes, including lysosomal homeostasis, cautioned for clinical inhibition of S1P. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.
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Liu L, Lee WS, Doray B, Kornfeld S. Engineering of GlcNAc-1-Phosphotransferase for Production of Highly Phosphorylated Lysosomal Enzymes for Enzyme Replacement Therapy. Mol Ther Methods Clin Dev 2017; 5:59-65. [PMID: 28480305 PMCID: PMC5415318 DOI: 10.1016/j.omtm.2017.03.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/22/2017] [Indexed: 12/27/2022]
Abstract
Several lysosomal enzymes currently used for enzyme replacement therapy in patients with lysosomal storage diseases contain very low levels of mannose 6-phosphate, limiting their uptake via mannose 6-phosphate receptors on the surface of the deficient cells. These enzymes are produced at high levels by mammalian cells and depend on endogenous GlcNAc-1-phosphotransferase α/β precursor to phosphorylate the mannose residues on their glycan chains. We show that co-expression of an engineered truncated GlcNAc-1-phosphotransferase α/β precursor and the lysosomal enzyme of interest in the producing cells resulted in markedly increased phosphorylation and cellular uptake of the secreted lysosomal enzyme. This method also results in the production of highly phosphorylated acid β-glucocerebrosidase, a lysosomal enzyme that normally has just trace amounts of this modification.
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Affiliation(s)
- Lin Liu
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Wang-Sik Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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Liu L, Lee WS, Doray B, Kornfeld S. Role of spacer-1 in the maturation and function of GlcNAc-1-phosphotransferase. FEBS Lett 2017; 591:47-55. [PMID: 27981560 DOI: 10.1002/1873-3468.12525] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 11/10/2022]
Abstract
The UDP-GlcNAc:lysosomal enzyme, N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-PT), is an α2 β2 γ2 hexamer that mediates the initial step in the formation of the mannose 6-phosphate targeting signal on newly synthesized lysosomal acid hydrolases. The GNPTAB gene encodes the 1256 amino acid long α/β precursor which is normally cleaved at K928 in the early Golgi by Site-1 protease (S1P). Here, we show that removal of the so-called 'spacer-1' domain (residues 86-322) results in cleavage almost exclusively at a second S1P consensus sequence located upstream of K928. In addition, GlcNAc-1-PT lacking spacer-1 exhibits enhanced phosphorylation of several non-lysosomal glycoproteins, while the phosphorylation of lysosomal acid hydrolases is not altered. In view of these effects on the maturation and function of GlcNAc-1-PT, we suggest renaming `spacer-1' the `regulatory-1' domain.
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Affiliation(s)
- Lin Liu
- 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
| | - 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
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11
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van Meel E, Kornfeld S. Mucolipidosis III GNPTG Missense Mutations Cause Misfolding of the γ Subunit of GlcNAc-1-Phosphotransferase. Hum Mutat 2016; 37:623-6. [PMID: 27038293 DOI: 10.1002/humu.22993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/08/2016] [Indexed: 11/08/2022]
Abstract
The lysosomal storage disorder ML III γ is caused by defects in the γ subunit of UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase, the enzyme that tags lysosomal enzymes with the mannose 6-phosphate lysosomal targeting signal. In patients with this disorder, most of the newly synthesized lysosomal enzymes are secreted rather than being sorted to lysosomes, resulting in increased levels of these enzymes in the plasma. Several missense mutations in GNPTG, the gene encoding the γ subunit, have been reported in mucolipidosis III γ patients. However, in most cases, the impact of these mutations on γ subunit function has remained unclear. Here, we report that the variants c.316G>A (p.G106S), c.376G>A (p.G126S), and c.425G>A (p.C142Y) cause misfolding of the γ subunit, whereas another variant, c.857C>T (p.T286M), does not appear to alter γ subunit function. The misfolded γ subunits were retained in the ER and failed to rescue the lysosomal targeting of lysosomal acid glycosidases.
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Affiliation(s)
- Eline van Meel
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
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12
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Alegra T, Koppe T, Acosta A, Sarno M, Burin M, Kessler RG, Sperb-Ludwig F, Cury G, Baldo G, Matte U, Giugliani R, Schwartz IVD. Pitfalls in the prenatal diagnosis of mucolipidosis II alpha/beta: A case report. Meta Gene 2014; 2:403-6. [PMID: 25606425 PMCID: PMC4287872 DOI: 10.1016/j.mgene.2014.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/28/2014] [Accepted: 03/05/2014] [Indexed: 10/28/2022] Open
Abstract
Mucolipidosis II alpha/beta is an autosomal recessive disorder caused by deficient activity of GlcNAc-1-phosphotransferase. We report the prenatal diagnosis of a fetus who was found to exhibit normal levels of lysosomal enzymes in the amniotic fluid but low levels in amniocytes, and who was found to be heterozygous for the most common GNPTAB mutation. As in some carriers of Mucolipidosis II biochemical abnormalities may hinder prenatal diagnosis, we suggest DNA analysis should be performed whenever possible.
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Affiliation(s)
- Taciane Alegra
- Postgraduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | - Tiago Koppe
- Postgraduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil ; School of Medicine, UFRGS, Brazil
| | - Angelina Acosta
- Medical Genetics Service, Complexo Hospitalar Universitário Professor Edgard Santos, Brazil ; Department of Pediatrics, School of Medicine, Universidade Federal da Bahia (UFBA), Salvador, Brazil
| | - Manoel Sarno
- Department of Gynecology and Obstetrics, School of Medicine, UFBA, Salvador, Brazil
| | - Maira Burin
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil
| | - Rejane Gus Kessler
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil
| | - Fernanda Sperb-Ludwig
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil ; Gene Therapy Center, HCPA, Porto Alegre, Brazil ; BRAIN (Basic Research and Advanced Investigations in Neurosciences) Laboratory, HCPA, Porto Alegre, Brazil
| | - Gabriela Cury
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil ; Gene Therapy Center, HCPA, Porto Alegre, Brazil
| | | | | | - Roberto Giugliani
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil ; Department of Genetics, UFRGS, Porto Alegre, Brazil
| | - Ida Vanessa D Schwartz
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil ; BRAIN (Basic Research and Advanced Investigations in Neurosciences) Laboratory, HCPA, Porto Alegre, Brazil ; Department of Genetics, UFRGS, Porto Alegre, Brazil
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Liu S, Zhang W, Shi H, Meng Y, Qiu Z. Three novel homozygous mutations in the GNPTG gene that cause mucolipidosis type III gamma. Gene 2013; 535:294-8. [PMID: 24316125 DOI: 10.1016/j.gene.2013.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/30/2013] [Accepted: 11/04/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mucolipidosis type III gamma (MLIII gamma) is an autosomal recessive disease caused by a mutation in the GNPTG gene, which encodes the γ subunit of the N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase). This protein plays a key role in the transport of lysosomal hydrolases to the lysosome. METHODS Three Chinese children with typical skeletal abnormalities of MLIII were identified, who were from unrelated consanguineous families. After obtaining informed consent, genomic DNA was isolated from the patients and their parents. Direct sequencing of the GNPTG and GNPTAB genes was performed using standard PCR reactions. RESULTS The three probands showed clinical features typical of MLIII gamma, such as joint stiffness and vertebral scoliosis without coarsened facial features. Mutation analysis of the GNPTG gene showed that three novel mutations were identified, two in exon seven [c.425G>A (p.Cys142Val)] and [c.515dupC (p.His172Profs27X)], and one in exon eight [c.609+1G>C]. Their parents were determined to be heterozygous carriers when compared to the reference sequence in GenBank on NCBI. CONCLUSIONS Mutation of the GNPTG gene is the cause of MLIII gamma in our patients. Our findings expand the mutation spectrum of the GNPTG gene and extend the knowledge of the phenotype-genotype correlation of the disease.
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Affiliation(s)
- Shuang Liu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China
| | - Weimin Zhang
- Clinical Research Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, PR China
| | - Huiping Shi
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Yan Meng
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, PR China
| | - Zhengqing Qiu
- Department of Pediatrics, PUMC Hospital, CAMS&PUMC, Beijing 100730, PR China.
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