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Budhraja R, Radenkovic S, Jain A, Muffels IJJ, Ismaili MHA, Kozicz T, Pandey A, Morava E. Liposome-encapsulated mannose-1-phosphate therapy improves global N-glycosylation in different congenital disorders of glycosylation. Mol Genet Metab 2024; 142:108487. [PMID: 38733638 DOI: 10.1016/j.ymgme.2024.108487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/22/2024] [Accepted: 05/02/2024] [Indexed: 05/13/2024]
Abstract
Phosphomannomutase 2 (PMM2) converts mannose-6-phospahate to mannose-1-phosphate; the substrate for GDP-mannose, a building block of the glycosylation biosynthetic pathway. Pathogenic variants in the PMM2 gene have been shown to be associated with protein hypoglycosylation causing PMM2-congenital disorder of glycosylation (PMM2-CDG). While mannose supplementation improves glycosylation in vitro, but not in vivo, we hypothesized that liposomal delivery of mannose-1-phosphate could increase the stability and delivery of the activated sugar to enter the targeted compartments of cells. Thus, we studied the effect of liposome-encapsulated mannose-1-P (GLM101) on global protein glycosylation and on the cellular proteome in skin fibroblasts from individuals with PMM2-CDG, as well as in individuals with two N-glycosylation defects early in the pathway, namely ALG2-CDG and ALG11-CDG. We leveraged multiplexed proteomics and N-glycoproteomics in fibroblasts derived from different individuals with various pathogenic variants in PMM2, ALG2 and ALG11 genes. Proteomics data revealed a moderate but significant change in the abundance of some of the proteins in all CDG fibroblasts upon GLM101 treatment. On the other hand, N-glycoproteomics revealed the GLM101 treatment enhanced the expression levels of several high-mannose and complex/hybrid glycopeptides from numerous cellular proteins in individuals with defects in PMM2 and ALG2 genes. Both PMM2-CDG and ALG2-CDG exhibited several-fold increase in glycopeptides bearing Man6 and higher glycans and a decrease in Man5 and smaller glycan moieties, suggesting that GLM101 helps in the formation of mature glycoforms. These changes in protein glycosylation were observed in all individuals irrespective of their genetic variants. ALG11-CDG fibroblasts also showed increase in high mannose glycopeptides upon treatment; however, the improvement was not as dramatic as the other two CDG. Overall, our findings suggest that treatment with GLM101 overcomes the genetic block in the glycosylation pathway and can be used as a potential therapy for CDG with enzymatic defects in early steps in protein N-glycosylation.
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Affiliation(s)
- Rohit Budhraja
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - Silvia Radenkovic
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Anu Jain
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - Irena J J Muffels
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA; Department of Genetics and Genomics Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Tamas Kozicz
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA; Department of Genetics and Genomics Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Anatomy, University of Pécs Medical School, 7624 Pécs, Hungary
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA; Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India.
| | - Eva Morava
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA; Department of Genetics and Genomics Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Biophysics, University of Pécs Medical School, 7624 Pécs, Hungary.
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Martínez Duncker I, Mata-Salgado D, Shammas I, Ranatunga W, Daniel EJP, Cruz Muñoz ME, Abreu M, Mora-Montes H, He M, Morava E, Zafra de la Rosa G. Case report: Novel genotype of ALG2-CDG and confirmation of the heptasaccharide glycan (NeuAc-Gal-GlcNAc-Man2-GlcNAc2) as a specific diagnostic biomarker. Front Genet 2024; 15:1363558. [PMID: 38770420 PMCID: PMC11102957 DOI: 10.3389/fgene.2024.1363558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 04/08/2024] [Indexed: 05/22/2024] Open
Abstract
This report outlines the case of a child affected by a type of congenital disorder of glycosylation (CDG) known as ALG2-CDG (OMIM 607906), presenting as a congenital myasthenic syndrome (CMS) caused by variants identified in ALG2, which encodes an α1,3-mannosyltransferase (EC 2.4.1.132) involved in the early steps of N-glycosylation. To date, fourteen cases of ALG2-CDG have been documented worldwide. From birth, the child experienced perinatal asphyxia, muscular weakness, feeding difficulties linked to an absence of the sucking reflex, congenital hip dislocation, and hypotonia. Over time, additional complications emerged, such as inspiratory stridor, gastroesophageal reflux, low intake, recurrent seizures, respiratory infections, an inability to maintain the head upright, and a global developmental delay. Whole genome sequencing (WGS) revealed the presence of two ALG2 variants in compound heterozygosity: a novel variant c.1055_1056delinsTGA p.(Ser352Leufs*3) and a variant of uncertain significance (VUS) c.964C>A p.(Pro322Thr). Additional studies, including determination of carbohydrate-deficient transferrin (CDT) revealed a mild type I CDG pattern and the presence of an abnormal transferrin glycoform containing a linear heptasaccharide consisting of one sialic acid, one galactose, one N-acetyl-glucosamine, two mannoses and two N-acetylglucosamines (NeuAc-Gal-GlcNAc-Man2-GlcNAc2), ALG2-CDG diagnostic biomarker, confirming the pathogenicity of these variants.
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Affiliation(s)
- Ivan Martínez Duncker
- Laboratorio de Glicobiología Humana y Diagnóstico Molecular, Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | - Denisse Mata-Salgado
- Laboratorio de Glicobiología Humana y Diagnóstico Molecular, Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | - Ibrahim Shammas
- Department of Clinical Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Wasantha Ranatunga
- Department of Clinical Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
| | - Earnest James Paul Daniel
- Palmieri Metabolic Disease Laboratory, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Mario E. Cruz Muñoz
- Laboratorio de Inmunología Molecular, Facultad de Medicina, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | | | - Héctor Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato, Mexico
| | - Miao He
- Palmieri Metabolic Disease Laboratory, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Eva Morava
- Department of Clinical Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States
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Sakson R, Beedgen L, Bernhard P, Alp KM, Lübbehusen N, Röth R, Niesler B, Luzarowski M, Shevchuk O, Mayer MP, Thiel C, Ruppert T. Targeted Proteomics Reveals Quantitative Differences in Low-Abundance Glycosyltransferases of Patients with Congenital Disorders of Glycosylation. Int J Mol Sci 2024; 25:1191. [PMID: 38256263 PMCID: PMC10816918 DOI: 10.3390/ijms25021191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Protein glycosylation is an essential post-translational modification in all domains of life. Its impairment in humans can result in severe diseases named congenital disorders of glycosylation (CDGs). Most of the glycosyltransferases (GTs) responsible for proper glycosylation are polytopic membrane proteins that represent challenging targets in proteomics. We established a multiple reaction monitoring (MRM) assay to comprehensively quantify GTs involved in the processes of N-glycosylation and O- and C-mannosylation in the endoplasmic reticulum. High robustness was achieved by using an enriched membrane protein fraction of isotopically labeled HEK 293T cells as an internal protein standard. The analysis of primary skin fibroblasts from eight CDG type I patients with impaired ALG1, ALG2, and ALG11 genes, respectively, revealed a substantial reduction in the corresponding protein levels. The abundance of the other GTs, however, remained unchanged at the transcript and protein levels, indicating that there is no fail-safe mechanism for the early steps of glycosylation in the endoplasmic reticulum. The established MRM assay was shared with the scientific community via the commonly used open source Skyline software environment, including Skyline Batch for automated data analysis. We demonstrate that another research group could easily reproduce all analysis steps, even while using different LC-MS hardware.
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Affiliation(s)
- Roman Sakson
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
- Heidelberg Biosciences International Graduate School (HBIGS), Heidelberg University, 69120 Heidelberg, Germany
| | - Lars Beedgen
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Patrick Bernhard
- Institute for Surgical Pathology, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - K. Merve Alp
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Nicole Lübbehusen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Ralph Röth
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Beate Niesler
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, 69120 Heidelberg, Germany
| | - Marcin Luzarowski
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Olga Shevchuk
- Department of Immunodynamics, Institute of Experimental Immunology and Imaging, University Hospital Essen, 45147 Essen, Germany
| | - Matthias P. Mayer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Christian Thiel
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Thomas Ruppert
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
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Lee HF, Chi CS. Congenital disorders of glycosylation and infantile epilepsy. Epilepsy Behav 2023; 142:109214. [PMID: 37086590 DOI: 10.1016/j.yebeh.2023.109214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 04/01/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a group of rare inherited metabolic disorders caused by defects in various defects of protein or lipid glycosylation pathways. The symptoms and signs of CDG usually develop in infancy. Epilepsy is commonly observed in CDG individuals and is often a presenting symptom. These epilepsies can present across the lifespan, share features of refractoriness to antiseizure medications, and are often associated with comorbid developmental delay, psychomotor regression, intellectual disability, and behavioral problems. In this review, we discuss CDG and infantile epilepsy, focusing on an overview of clinical manifestations and electroencephalographic features. Finally, we propose a tiered approach that will permit a clinician to systematically investigate and identify CDG earlier, and furthermore, to provide genetic counseling for the family.
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Affiliation(s)
- Hsiu-Fen Lee
- Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, 145, Xingda Rd., Taichung 402, Taiwan; Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, 1650, Taiwan Boulevard Sec. 4, Taichung 407, Taiwan.
| | - Ching-Shiang Chi
- Division of Pediatric Neurology, Children's Medical Center, Taichung Veterans General Hospital, 1650, Taiwan Boulevard Sec. 4, Taichung 407, Taiwan.
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Ohno K, Ohkawara B, Shen XM, Selcen D, Engel AG. Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review. Int J Mol Sci 2023; 24:ijms24043730. [PMID: 36835142 PMCID: PMC9961056 DOI: 10.3390/ijms24043730] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/09/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.
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Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
- Correspondence: (K.O.); (A.G.E.)
| | - Bisei Ohkawara
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Xin-Ming Shen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Duygu Selcen
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
| | - Andrew G. Engel
- Department of Neurology and Neuromuscular Research Laboratory, Mayo Clinic, Rochester, MN 55905, USA
- Correspondence: (K.O.); (A.G.E.)
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Elsharkawi I, Wongkittichote P, James Paul Daniel E, Starosta RT, Ueda K, Ng BG, Freeze HH, He M, Shinawi M. DDOST-CDG: Clinical and molecular characterization of a third patient with a milder and a predominantly movement disorder phenotype. J Inherit Metab Dis 2023; 46:92-100. [PMID: 36214423 PMCID: PMC9852036 DOI: 10.1002/jimd.12565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 09/02/2022] [Accepted: 09/30/2022] [Indexed: 01/22/2023]
Abstract
Congenital disorders of glycosylation (CDG) are a group of heterogeneous inherited metabolic disorders affecting posttranslational protein modification. DDOST-CDG, caused by biallelic pathogenic variants in DDOST which encodes dolichyl-diphospho-oligosaccharide-protein glycosyltransferase, a subunit of N-glycosylation oligosaccharyltransferase (OST) complex, is an ultra-rare condition that has been described in two patients only. The main clinical features in the two reported patients include profound developmental delay, failure to thrive, and hypotonia. In addition, both patients had abnormal transferrin glycosylation. Here, we report an 18-year-old male who presented with moderate developmental delay, progressive opsoclonus, myoclonus, ataxia, tremor, and dystonia. Biochemical studies by carbohydrate deficient transferrin analysis showed a type I CDG pattern. Exome sequencing identified compound heterozygous variants in DDOST: a maternally inherited variant, c.1142dupT (p.Leu381Phefs*11), and a paternally inherited variant, c.661 T > C (p.Ser221Pro). Plasma N-glycan profiling showed mildly increased small high mannose glycans including Man0-5 GlcNAc2, a pattern consistent with what was previously reported in DDOST-CDG or defects in other subunits of OST complex. Western blot analysis on patient's fibroblasts revealed decreased expression of DDOST and reduced intracellular N-glycosylation, as evident by the biomarkers ICAM-1 and LAMP2. Our study highlights the clinical variability, expands the clinical and biochemical phenotypes, and describes new genotype, which all are essential for diagnosing and managing patients with DDOST-CDG.
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Affiliation(s)
- Ibrahim Elsharkawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Parith Wongkittichote
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Rodrigo Tzovenos Starosta
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Keisuke Ueda
- Division of Pediatric Neurology, Department of Neurology, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
| | - Bobby G. Ng
- Human Genetics Program, Sanford Children’s Health Research Center, La Jolla, CA, USA
| | - Hudson H. Freeze
- Human Genetics Program, Sanford Children’s Health Research Center, La Jolla, CA, USA
| | - Miao He
- Palmieri Metabolic Disease Laboratory, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, St. Louis Children’s Hospital, Washington University School of Medicine, St. Louis, MO, USA
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Topological and enzymatic analysis of human Alg2 mannosyltransferase reveals its role in lipid-linked oligosaccharide biosynthetic pathway. Commun Biol 2022; 5:117. [PMID: 35136180 PMCID: PMC8827073 DOI: 10.1038/s42003-022-03066-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/20/2022] [Indexed: 11/14/2022] Open
Abstract
N-glycosylation starts with the biosynthesis of lipid-linked oligosaccharide (LLO) on the endoplasmic reticulum (ER). Alg2 mannosyltransferase adds both the α1,3- and α1,6-mannose (Man) onto ManGlcNAc2-pyrophosphate-dolichol (M1Gn2-PDol) in either order to generate the branched M3Gn2-PDol product. The well-studied yeast Alg2 interacts with ER membrane through four hydrophobic domains. Unexpectedly, we show that Alg2 structure has diverged between yeast and humans. Human Alg2 (hAlg2) associates with the ER via a single membrane-binding domain and is markedly more stable in vitro. These properties were exploited to develop a liquid chromatography-mass spectrometry quantitative kinetics assay for studying purified hAlg2. Under physiological conditions, hAlg2 prefers to transfer α1,3-Man onto M1Gn2 before adding the α1,6-Man. However, this bias is altered by an excess of GDP-Man donor or an increased level of M1Gn2 substrate, both of which trigger production of the M2Gn2(α-1,6)-PDol. These results suggest that Alg2 may regulate the LLO biosynthetic pathway by controlling accumulation of M2Gn2 (α-1,6) intermediate. Despite the conservation of N-glycosylation, human and yeast Alg2 structures have diverged with distinct ER-binding topologies. The human enzyme is more stable than the yeast orthologue, and its activity is modulated by the concentration of donor or acceptor substrate.
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Kanduc D. Thromboses and Hemostasis Disorders Associated with COVID-19: The Possible Causal Role of Cross-Reactivity and Immunological Imprinting. Glob Med Genet 2021; 8:162-170. [PMID: 34877574 PMCID: PMC8635820 DOI: 10.1055/s-0041-1731068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 04/26/2021] [Indexed: 12/13/2022] Open
Abstract
By examining the issue of the thromboses and hemostasis disorders associated with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) through the lens of cross-reactivity, it was found that 60 pentapeptides are shared by SARS-CoV-2 spike glycoprotein (gp) and human proteins that— when altered, mutated, deficient or, however, improperly functioning— cause vascular diseases, thromboembolic complications, venous thrombosis, thrombocytopenia, coagulopathies, and bleeding, inter alia. The peptide commonality has a relevant immunological potential as almost all of the shared sequences are present in experimentally validated SARS-CoV-2 spike gp-derived epitopes, thus supporting the possibility of cross-reactions between the viral gp and the thromboses-related human proteins. Moreover, many of the shared peptide sequences are also present in pathogens to which individuals have previously been exposed following natural infection or vaccinal routes, and of which the immune system has stored imprint. Such an immunological memory might rapidly trigger anamnestic secondary cross-reactive responses of extreme affinity and avidity, in this way explaining the thromboembolic adverse events that can associate with SARS-CoV-2 infection or active immunization.
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Affiliation(s)
- Darja Kanduc
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
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Padilla-Mejia NE, Makarov AA, Barlow LD, Butterfield ER, Field MC. Evolution and diversification of the nuclear envelope. Nucleus 2021; 12:21-41. [PMID: 33435791 PMCID: PMC7889174 DOI: 10.1080/19491034.2021.1874135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic cells arose ~1.5 billion years ago, with the endomembrane system a central feature, facilitating evolution of intracellular compartments. Endomembranes include the nuclear envelope (NE) dividing the cytoplasm and nucleoplasm. The NE possesses universal features: a double lipid bilayer membrane, nuclear pore complexes (NPCs), and continuity with the endoplasmic reticulum, indicating common evolutionary origin. However, levels of specialization between lineages remains unclear, despite distinct mechanisms underpinning various nuclear activities. Several distinct modes of molecular evolution facilitate organellar diversification and to understand which apply to the NE, we exploited proteomic datasets of purified nuclear envelopes from model systems for comparative analysis. We find enrichment of core nuclear functions amongst the widely conserved proteins to be less numerous than lineage-specific cohorts, but enriched in core nuclear functions. This, together with consideration of additional evidence, suggests that, despite a common origin, the NE has evolved as a highly diverse organelle with significant lineage-specific functionality.
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Affiliation(s)
- Norma E. Padilla-Mejia
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Alexandr A. Makarov
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Lael D. Barlow
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Erin R. Butterfield
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Mark C. Field
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České, Czech Republic
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10
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Novel pathogenic ALG2 mutation causing congenital myasthenic syndrome: A case report. Neuromuscul Disord 2021; 32:80-83. [PMID: 34980536 DOI: 10.1016/j.nmd.2021.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 11/23/2022]
Abstract
ALG2 mutations are extremely rare causes of congenital myasthenic syndromes (CMS). The clinical phenotype and treatment response is therefore not well described. We present the case of a baby who immediately after birth presented with pronounced truncal hypotonia, proximal muscle weakness and feeding difficulties. Single fibre electromyography showed neuromuscular transmission failure and salbutamol and ephedrine treatment improved both muscle weakness and neuromuscular transmission. Genetic analysis revealed a likely pathogenic variant c.1040del, p.(Gly347Valfs*27) in exon 2 and a variant of uncertain significance, c.239G>A, p.(Gly80Asp) in exon 1 of the ALG2 gene. Western blot in whole cell lysates of HEK293 cells transfected with p.Gly80Asp, or p.Gly347Valfs*27 expression constructs indicated that p.Gly347Valfs*27 is likely a null allele and p.Gly80Asp is pathogenic through marked reduction of ALG2 expression. This case highlights the utility of functional studies in clarifying variants of unknown significance, in suspected cases of CMS.
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Liver Involvement in Congenital Disorders of Glycosylation: A Systematic Review. J Pediatr Gastroenterol Nutr 2021; 73:444-454. [PMID: 34173795 PMCID: PMC9255677 DOI: 10.1097/mpg.0000000000003209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
An ever-increasing number of disturbances in glycosylation have been described to underlie certain unexplained liver diseases presenting either almost isolated or in a multi-organ context. We aimed to update previous literature screenings which had identified up to 23 forms of congenital disorders of glycosylation (CDG) with associated liver disease. We conducted a comprehensive literature search of three scientific electronic databases looking at articles published during the last 20 years (January 2000-October 2020). Eligible studies were case reports/series reporting liver involvement in CDG patients. Our systematic review led us to point out 41 forms of CDG where the liver is primarily affected (n = 7) or variably involved in a multisystem disease with mandatory neurological abnormalities (n = 34). Herein we summarize individual clinical and laboratory presentation characteristics of these 41 CDG and outline their main presentation and diagnostic cornerstones with the aid of two synoptic tables. Dietary supplementation strategies have hitherto been investigated only in seven of these CDG types with liver disease, with a wide range of results. In conclusion, the systematic review recognized a liver involvement in a somewhat larger number of CDG variants corresponding to about 30% of the total of CDG so far reported, and it is likely that the number may increase further. This information could assist in an earlier correct diagnosis and a possibly proper management of these disorders.
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Gücüm S, Sakson R, Hoffmann M, Grote V, Becker C, Pakari K, Beedgen L, Thiel C, Rapp E, Ruppert T, Thumberger T, Wittbrodt J. A patient-based medaka alg2 mutant as a model for hypo-N-glycosylation. Development 2021; 148:269015. [PMID: 34106226 PMCID: PMC8217707 DOI: 10.1242/dev.199385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/04/2021] [Indexed: 11/20/2022]
Abstract
Defects in the evolutionarily conserved protein-glycosylation machinery during embryonic development are often fatal. Consequently, congenital disorders of glycosylation (CDG) in human are rare. We modelled a putative hypomorphic mutation described in an alpha-1,3/1,6-mannosyltransferase (ALG2) index patient (ALG2-CDG) to address the developmental consequences in the teleost medaka (Oryzias latipes). We observed specific, multisystemic, late-onset phenotypes, closely resembling the patient's syndrome, prominently in the facial skeleton and in neuronal tissue. Molecularly, we detected reduced levels of N-glycans in medaka and in the patient's fibroblasts. This hypo-N-glycosylation prominently affected protein abundance. Proteins of the basic glycosylation and glycoprotein-processing machinery were over-represented in a compensatory response, highlighting the regulatory topology of the network. Proteins of the retinal phototransduction machinery, conversely, were massively under-represented in the alg2 model. These deficiencies relate to a specific failure to maintain rod photoreceptors, resulting in retinitis pigmentosa characterized by the progressive loss of these photoreceptors. Our work has explored only the tip of the iceberg of N-glycosylation-sensitive proteins, the function of which specifically impacts on cells, tissues and organs. Taking advantage of the well-described human mutation has allowed the complex interplay of N-glycosylated proteins and their contribution to development and disease to be addressed.
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Affiliation(s)
- Sevinç Gücüm
- COS, Centre for Organismal Studies Heidelberg, Heidelberg University, 69120 Heidelberg, Germany.,HBIGS, Heidelberg Biosciences International Graduate School, Heidelberg University, 69120 Heidelberg, Germany
| | - Roman Sakson
- HBIGS, Heidelberg Biosciences International Graduate School, Heidelberg University, 69120 Heidelberg, Germany.,Core facility for Mass Spectrometry and Proteomics, Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Marcus Hoffmann
- Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Valerian Grote
- Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Clara Becker
- COS, Centre for Organismal Studies Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
| | - Kaisa Pakari
- COS, Centre for Organismal Studies Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
| | - Lars Beedgen
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Christian Thiel
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Erdmann Rapp
- Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany.,glyXera GmbH, 39120 Magdeburg, Germany
| | - Thomas Ruppert
- Core facility for Mass Spectrometry and Proteomics, Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Thomas Thumberger
- COS, Centre for Organismal Studies Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
| | - Joachim Wittbrodt
- COS, Centre for Organismal Studies Heidelberg, Heidelberg University, 69120 Heidelberg, Germany
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13
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Lhussiez V, Dubus E, Cesar Q, Acar N, Nandrot EF, Simonutti M, Audo I, Lizé E, Nguyen S, Geissler A, Bouchot A, Ansar M, Picaud S, Thauvin-Robinet C, Olivier-Faivre L, Duplomb L, Da Costa R. Cohen Syndrome-Associated Cataract Is Explained by VPS13B Functions in Lens Homeostasis and Is Modified by Additional Genetic Factors. Invest Ophthalmol Vis Sci 2021; 61:18. [PMID: 32915983 PMCID: PMC7488618 DOI: 10.1167/iovs.61.11.18] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Purpose Cohen syndrome (CS) is a rare genetic disorder caused by variants of the VPS13B gene. CS patients are affected with a severe form of retinal dystrophy, and in several cases cataracts also develop. The purpose of this study was to investigate the mechanisms and risk factors for cataract in CS, as well as to report on cataract surgeries in CS patients. Methods To understand how VPS13B is associated with visual impairments in CS, we generated the Vps13b∆Ex3/∆Ex3 mouse model. Mice from 1 to 3 months of age were followed by ophthalmoscopy and slit-lamp examinations. Phenotypes were investigated by histology, immunohistochemistry, and western blot. Literature analysis was performed to determine specific characteristic features of cataract in CS and to identify potential genotype–phenotype correlations. Results Cataracts rapidly developed in 2-month-old knockout mice and were present in almost all lenses at 3 months. Eye fundi appeared normal until cataract development. Lens immunostaining revealed that cataract formation was associated with the appearance of large vacuoles in the cortical area, epithelial–mesenchymal transition, and fibrosis. In later stages, cataracts became hypermature, leading to profound retinal remodeling due to inflammatory events. Literature analysis showed that CS-related cataracts display specific features compared to other forms of retinitis pigmentosa-related cataracts, and their onset is modified by additional genetic factors. Corroboratively, we were able to isolate a subline of the Vps13b∆Ex3/∆Ex3 model with delayed cataract onset. Conclusions VPS13B participates in lens homeostasis, and the CS-related cataract development dynamic is linked to additional genetic factors.
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Affiliation(s)
- Vincent Lhussiez
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France
| | - Elisabeth Dubus
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAE, Université Bourgogne Franche-Comté, Dijon, France
| | - Quénol Cesar
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Niyazi Acar
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAE, Université Bourgogne Franche-Comté, Dijon, France
| | - Emeline F Nandrot
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Manuel Simonutti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Eléonore Lizé
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France
| | - Sylvie Nguyen
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France
| | - Audrey Geissler
- Plateforme d'Imagerie Cellulaire DImaCell (site CellImaP), INSERM LNC UMR1231, Dijon, France
| | - André Bouchot
- Plateforme d'Imagerie Cellulaire DImaCell (site CellImaP), INSERM LNC UMR1231, Dijon, France
| | - Muhammad Ansar
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland.,Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Christel Thauvin-Robinet
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France.,FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, CHU Dijon Bourgogne, Dijon, France
| | - Laurence Olivier-Faivre
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France.,FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France.,Centre de Référence Anomalies du Développement et Syndromes Malformatifs, CHU Dijon Bourgogne, Dijon, France
| | - Laurence Duplomb
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France.,FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France
| | - Romain Da Costa
- INSERM UMR1231, Equipe GAD, Université de Bourgogne Franche Comté, Dijon, France.,FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France
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14
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Papazoglu GM, Cubilla M, Pereyra M, de Kremer RD, Pérez B, Sturiale L, Asteggiano CG. Mass spectrometry glycophenotype characterization of ALG2-CDG in Argentinean patients with a new genetic variant in homozygosis. Glycoconj J 2021; 38:191-200. [PMID: 33644825 DOI: 10.1007/s10719-021-09976-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 12/16/2022]
Abstract
Human ALG2 encodes an α 1,3mannosyltransferase that catalyzes the first steps in the synthesis of N-glycans in the endoplasmic reticulum. Variants in ALG2cause a congenital disorder of glycosylation (CDG) known as ALG2-CDG. Up to date, nine ALG2-CDG patients have been reported worldwide. ALG2-CDG is a rare autosomal recessive inherited disorder characterized by neurological involvement, convulsive syndrome of unknown origin, axial hypotonia, and mental and motor regression. In this study, we used MALDI-TOF MS to define both total serum protein and transferrin (Tf) N-glycan phenotypes in three ALG2-CDG patients carrying a c.752G > T, p.Arg251Leu ALG2 missense variant in homozygous state, as determined by exome sequencing. Comparing it to control samples, we have observed Tf under-occupancy of glycosylation site(s) typical of a defective N-glycan assembly and the occurrence of oligomannose and hybrid type N-glycans. Moreover, we have observed a slight oligomannose accumulation in total serum glyco-profiles. The increased heterogeneity of serum N-glycome in the studied patients suggests a marginal disarrangement of the glycan processing in ALG2-CDG. Previous studies reported on slightly increased concentrations of abnormal serum N-glycans in CDG-I due to defects in the mannosylation steps of dolichol-linked oligosaccharide biosynthesis. This preliminary work aims at considering serum N-glycan accumulation of high mannosylated glycoforms, such as oligomannose and hybrid type N-glycans, as potential diagnostic signals for ALG2-CDG patients.
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Affiliation(s)
- Gabriela Magali Papazoglu
- Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Santísima Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, X5014AKN, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
| | - Marisa Cubilla
- Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Santísima Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, X5014AKN, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
| | - Marcela Pereyra
- Servicio de Crecimiento y Desarrollo, Hospital Pediátrico HumbertoNotti, Mendoza, Argentina
| | - Raquel Dodelson de Kremer
- Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Santísima Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, X5014AKN, Córdoba, Argentina
| | - Belén Pérez
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), Centro de Biología Molecular Severo Ochoa CSIC-UAM, CIBERER, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain
| | - Luisa Sturiale
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Carla Gabriela Asteggiano
- Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Santísima Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, X5014AKN, Córdoba, Argentina.
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina.
- Facultad de Ciencias de la Salud, Carrera Medicina, Universidad Católica de Córdoba (UCC), Jacinto Ríos 571 (X5004ASK), B° General Paz, Córdoba, Argentina.
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15
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Bogenschutz EL, Fox ZD, Farrell A, Wynn J, Moore B, Yu L, Aspelund G, Marth G, Yandell M, Shen Y, Chung WK, Kardon G. Deep whole-genome sequencing of multiple proband tissues and parental blood reveals the complex genetic etiology of congenital diaphragmatic hernias. HGG ADVANCES 2020; 1:100008. [PMID: 33263113 PMCID: PMC7703690 DOI: 10.1016/j.xhgg.2020.100008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/07/2020] [Indexed: 12/17/2022] Open
Abstract
The diaphragm is critical for respiration and separation of the thoracic and abdominal cavities, and defects in diaphragm development are the cause of congenital diaphragmatic hernias (CDH), a common and often lethal birth defect. The genetic etiology of CDH is complex. Single-nucleotide variants (SNVs), insertions/deletions (indels), and structural variants (SVs) in more than 150 genes have been associated with CDH, although few genes are recurrently mutated in multiple individuals and mutated genes are incompletely penetrant. This suggests that multiple genetic variants in combination, other not-yet-investigated classes of variants, and/or nongenetic factors contribute to CDH etiology. However, no studies have comprehensively investigated in affected individuals the contribution of all possible classes of variants throughout the genome to CDH etiology. In our study, we used a unique cohort of four individuals with isolated CDH with samples from blood, skin, and diaphragm connective tissue and parental blood and deep whole-genome sequencing to assess germline and somatic de novo and inherited SNVs, indels, and SVs. In each individual we found a different mutational landscape that included germline de novo and inherited SNVs and indels in multiple genes. We also found in two individuals a 343 bp deletion interrupting an annotated enhancer of the CDH-associated gene GATA4, and we hypothesize that this common SV (found in 1%-2% of the population) acts as a sensitizing allele for CDH. Overall, our comprehensive reconstruction of the genetic architecture of four CDH individuals demonstrates that the etiology of CDH is heterogeneous and multifactorial.
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Affiliation(s)
- Eric L. Bogenschutz
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Zac D. Fox
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Andrew Farrell
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- USTAR Center for Genetic Discovery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Julia Wynn
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Barry Moore
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- USTAR Center for Genetic Discovery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Lan Yu
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Gudrun Aspelund
- Department of Surgery, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Gabor Marth
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- USTAR Center for Genetic Discovery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Mark Yandell
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
- USTAR Center for Genetic Discovery, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Yufeng Shen
- Department of Systems Biology, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Biomedical Informatics, Columbia University Irving Medical Center, New York, NY 10032, USA
- JP Sulzberger Columbia Genome Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Wendy K. Chung
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Gabrielle Kardon
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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16
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Ondruskova N, Cechova A, Hansikova H, Honzik T, Jaeken J. Congenital disorders of glycosylation: Still "hot" in 2020. Biochim Biophys Acta Gen Subj 2020; 1865:129751. [PMID: 32991969 DOI: 10.1016/j.bbagen.2020.129751] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/12/2020] [Accepted: 08/27/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Congenital disorders of glycosylation (CDG) are inherited metabolic diseases caused by defects in the genes important for the process of protein and lipid glycosylation. With the ever growing number of the known subtypes and discoveries regarding the disease mechanisms and therapy development, it remains a very active field of study. SCOPE OF REVIEW This review brings an update on the CDG-related research since 2017, describing the novel gene defects, pathobiomechanisms, biomarkers and the patients' phenotypes. We also summarize the clinical guidelines for the most prevalent disorders and the current therapeutical options for the treatable CDG. MAJOR CONCLUSIONS In the majority of the 23 new CDG, neurological involvement is associated with other organ disease. Increasingly, different aspects of cellular metabolism (e.g., autophagy) are found to be perturbed in multiple CDG. GENERAL SIGNIFICANCE This work highlights the recent trends in the CDG field and comprehensively overviews the up-to-date clinical recommendations.
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Affiliation(s)
- Nina Ondruskova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Anna Cechova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Hana Hansikova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Tomas Honzik
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.
| | - Jaak Jaeken
- Department of Paediatrics and Centre for Metabolic Diseases, KU Leuven and University Hospital Leuven, Leuven, Belgium.
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17
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Yeast Models of Phosphomannomutase 2 Deficiency, a Congenital Disorder of Glycosylation. G3-GENES GENOMES GENETICS 2019; 9:413-423. [PMID: 30530630 PMCID: PMC6385982 DOI: 10.1534/g3.118.200934] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Phosphomannomutase 2 Deficiency (PMM2-CDG) is the most common monogenic congenital disorder of glycosylation (CDG) affecting at least 800 patients globally. PMM2 orthologs are present in model organisms, including the budding yeast Saccharomyces cerevisiae gene SEC53. Here we describe conserved genotype-phenotype relationships across yeast and human patients between five PMM2 loss-of-function missense mutations and their orthologous SEC53 mutations. These alleles range in severity from folding defective (hypomorph) to dimerization defective (severe hypomorph) to catalytic dead (null). We included the first and second most common missense mutations – R141H, F119L respectively– and the most common compound heterozygote genotype – PMM2R141H/F119L – observed in PMM2-CDG patients. Each mutation described is expressed in haploid as well as homozygous and heterozygous diploid yeast cells at varying protein expression levels as either SEC53 protein variants or PMM2 protein variants. We developed a 384-well-plate, growth-based assay for use in a screen of the 2,560-compound Microsource Spectrum library of approved drugs, experimental drugs, tool compounds and natural products. We identified three compounds that suppress growth defects of SEC53 variants, F126L and V238M, based on the biochemical defect of the allele, protein abundance or ploidy. The rare PMM2 E139K protein variant is fully functional in yeast cells, suggesting that its pathogenicity in humans is due to the underlying DNA mutation that results in skipping of exon 5 and a nonfunctional truncated protein. Together, these results demonstrate that yeast models can be used to characterize known and novel PMM2 patient alleles in quantitative growth and enzymatic activity assays, and used as patient avatars for PMM2-CDG drug screens yielding compounds that could be rapidly cross-validated in zebrafish, rodent and human organoid models.
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18
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Abstract
Congenital disorders of glycosylation (CDG) is a genetically heterogeneous and clinically polymorphic group of diseases caused by defects in various enzymes, the synthesis and processing of N-linked glycans or oligosaccharides into glycoproteins. Approximately half of all proteins expressed in cells are glycosylated to achieve their full functionality. Basically there are 2 variants of glycosylation: N-glycosylation and O-glycosylation. N-glycans are bound to the amide group of aspartine, whereas O-glycans are bonded to the hydroxyl group of serine or threonine. Synthesis of N-glycans occurs in 3 stages: the formation of nucleotide-linked sugars, assembly (in the cytosol and endoplasmic reticulum) and treatment (in the Golgi apparatus). Synthesis of O-glycans occurs mainly in the Golgi apparatus. The most frequently identified types of CDG are associated with a defect in the N-glycosylation pathway. CDGs are typically multisystem disorders with varying clinical manifestations such as hepatomegaly, cholestasis, liver failure, developmental delay, hypotonia, convulsions, facial dysmorphism and gastrointestinal disorders. Also histological findings showed liver fibrosis, malformation of the ducts, cirrhosis, and steatosis. CDGs typically present in the first months of life, and about 20% of patients do not survive to 5 years. The first line of CDG screening is based on the analysis of N-glycosylation of transf ferin. Exome sequencing or targeted gene panel is used for diagnosis. Several CDG subtypes are amenable to teraphy with mannose and galactose.
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19
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Asteggiano CG, Papazoglu M, Bistué Millón MB, Peralta MF, Azar NB, Spécola NS, Guelbert N, Suldrup NS, Pereyra M, Dodelson de Kremer R. Ten years of screening for congenital disorders of glycosylation in Argentina: case studies and pitfalls. Pediatr Res 2018; 84:837-841. [PMID: 30397276 DOI: 10.1038/s41390-018-0206-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/19/2018] [Accepted: 09/25/2018] [Indexed: 11/09/2022]
Abstract
BACKGROUND Congenital Disorders of Glycosylation (CDG) are genetic diseases caused by hypoglycosylation of glycoproteins and glycolipids. Most CDG are multisystem disorders with mild to severe involvement. METHODS We studied 554 patients (2007-2017) with a clinical phenotype compatible with a CDG. Screening was performed by serum transferrin isoelectric focusing. The diagnosis was confirmed by genetic testing (Sanger or exome sequencing). RESULTS A confirmed abnormal pattern was found in nine patients. Seven patients showed a type 1 pattern: four with PMM2-CDG, two with ALG2-CDG, and one with classical galactosemia. A type 2 pattern was found in two patients: one with a CDG-IIx and one with a transferrin protein variant. Abnormal transferrin pattern were observed in a patient with a myopathy due to a COL6A2 gene variant. CONCLUSIONS CDG screening in Argentina from 2007 to 2017 revealed 4 PMM2-CDG patients, 2 ALG2-CDG patients with a novel homozygous gene variant and 1 CDG-IIx.
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Affiliation(s)
- Carla Gabriela Asteggiano
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina.
| | - Magali Papazoglu
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - María Beatriz Bistué Millón
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - María Fernanda Peralta
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - Nydia Beatriz Azar
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | | | - Norberto Guelbert
- Servicio de Enfermedades Metabólicas, Hospital de Niños de la Sma. Trinidad, Ferroviarios 1250, Córdoba, Argentina
| | | | - Marcela Pereyra
- Servicio de Crecimiento y Desarrollo, Hospital Pediátrico Humberto Notti, Mendoza, Argentina
| | - Raquel Dodelson de Kremer
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
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20
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Rodríguez Cruz PM, Palace J, Beeson D. The Neuromuscular Junction and Wide Heterogeneity of Congenital Myasthenic Syndromes. Int J Mol Sci 2018; 19:ijms19061677. [PMID: 29874875 PMCID: PMC6032286 DOI: 10.3390/ijms19061677] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/16/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are genetic disorders characterised by impaired neuromuscular transmission. This review provides an overview on CMS and highlights recent advances in the field, including novel CMS causative genes and improved therapeutic strategies. CMS due to mutations in SLC5A7 and SLC18A3, impairing the synthesis and recycling of acetylcholine, have recently been described. In addition, a novel group of CMS due to mutations in SNAP25B, SYT2, VAMP1, and UNC13A1 encoding molecules implicated in synaptic vesicles exocytosis has been characterised. The increasing number of presynaptic CMS exhibiting CNS manifestations along with neuromuscular weakness demonstrate that the myasthenia can be only a small part of a much more extensive disease phenotype. Moreover, the spectrum of glycosylation abnormalities has been increased with the report that GMPPB mutations can cause CMS, thus bridging myasthenic disorders with dystroglycanopathies. Finally, the discovery of COL13A1 mutations and laminin α5 deficiency has helped to draw attention to the role of extracellular matrix proteins for the formation and maintenance of muscle endplates. The benefit of β2-adrenergic agonists alone or combined with pyridostigmine or 3,4-Dyaminopiridine is increasingly being reported for different subtypes of CMS including AChR-deficiency and glycosylation abnormalities, thus expanding the therapeutic repertoire available.
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Affiliation(s)
- Pedro M Rodríguez Cruz
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
| | - Jacqueline Palace
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DS, UK.
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Abstract
West syndrome (WS) is an early life epileptic encephalopathy associated with infantile spasms, interictal electroencephalography (EEG) abnormalities including high amplitude, disorganized background with multifocal epileptic spikes (hypsarrhythmia), and often neurodevelopmental impairments. Approximately 64% of the patients have structural, metabolic, genetic, or infectious etiologies and, in the rest, the etiology is unknown. Here we review the contribution of etiologies due to various metabolic disorders in the pathology of WS. These may include metabolic errors in organic molecules involved in amino acid and glucose metabolism, fatty acid oxidation, metal metabolism, pyridoxine deficiency or dependency, or acidurias in organelles such as mitochondria and lysosomes. We discuss the biochemical, clinical, and EEG features of these disorders as well as the evidence of how they may be implicated in the pathogenesis and treatment of WS. The early recognition of these etiologies in some cases may permit early interventions that may improve the course of the disease.
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Affiliation(s)
- Seda Salar
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
| | - Solomon L. Moshé
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Dominick P. Purpura Department of NeuroscienceMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Department of PediatricsMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
| | - Aristea S. Galanopoulou
- Laboratory of Developmental EpilepsySaul R. Korey Department of NeurologyMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
- Dominick P. Purpura Department of NeuroscienceMontefiore/Einstein Epilepsy CenterAlbert Einstein College of MedicineBronxNew YorkU.S.A.
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22
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Ng BG, Freeze HH. Perspectives on Glycosylation and Its Congenital Disorders. Trends Genet 2018; 34:466-476. [PMID: 29606283 DOI: 10.1016/j.tig.2018.03.002] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/04/2018] [Accepted: 03/05/2018] [Indexed: 12/12/2022]
Abstract
Congenital disorders of glycosylation (CDG) are a rapidly expanding group of metabolic disorders that result from abnormal protein or lipid glycosylation. They are often difficult to clinically diagnose because they broadly affect many organs and functions and lack clinical uniformity. However, recent technological advances in next-generation sequencing have revealed a treasure trove of new genetic disorders, expanded the knowledge of known disorders, and showed a critical role in infectious diseases. More comprehensive genetic tools specifically tailored for mammalian cell-based models have revealed a critical role for glycosylation in pathogen-host interactions, while also identifying new CDG susceptibility genes. We highlight recent advancements that have resulted in a better understanding of human glycosylation disorders, perspectives for potential future therapies, and mysteries for which we continue to seek new insights and solutions.
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Affiliation(s)
- Bobby G Ng
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Hudson H Freeze
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.
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23
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Abstract
PURPOSE OF REVIEW Congenital myasthenic syndromes (CMS) are a group of heterogeneous inherited disorders caused by mutations in genes encoding proteins essential for the integrity of neuromuscular transmission. This review updates the reader on recent findings that have expanded the phenotypic spectrum and suggested improved treatment strategies. RECENT FINDINGS The use of next-generation sequencing is continuing to unearth new genes in which mutations can give rise to defective neuromuscular transmission. The defective transmission may be part of an overall more complex phenotype in which there may be muscle, central nervous system or other involvement. Notably, mutations in series of genes encoding presynaptic proteins are being identified. Further work on mutations found in the AGRN-MUSK acetylcholine receptor clustering pathway has helped characterize the role of LRP4 and broadened the phenotypic spectrum for AGRN mutations. Mutations in another extracellular matrix protein, collagen 13A1 and in GMPPB have also been found to cause a CMS. Finally, there are an increasing number of reports for the beneficial effects of treatment with β2-adrenergic receptor agonists. SUMMARY Recent studies of the CMS illustrate the increasing complexity of the genetics, pathophysiological mechanisms and the need to tailor therapy for the genetic disorders of the neuromuscular junction.
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Li ST, Wang N, Xu XX, Fujita M, Nakanishi H, Kitajima T, Dean N, Gao XD. Alternative routes for synthesis of N-linked glycans by Alg2 mannosyltransferase. FASEB J 2018; 32:2492-2506. [PMID: 29273674 DOI: 10.1096/fj.201701267r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Asparagine ( N)-linked glycosylation requires the ordered, stepwise synthesis of lipid-linked oligosaccharide (LLO) precursor Glc3Man9GlcNAc2-pyrophosphate-dolichol (Glc3Man9Gn2-PDol) on the endoplasmic reticulum. The fourth and fifth steps of LLO synthesis are catalyzed by Alg2, an unusual mannosyltransferase (MTase) with two different MTase activities; Alg2 adds both an α1,3- and α1,6-mannose onto ManGlcNAc2-PDol to form the trimannosyl core Man3GlcNAc2-PDol. The biochemical properties of Alg2 are controversial and remain undefined. In this study, a liquid chromatography/mass spectrometry-based quantitative assay was established and used to analyze the MTase activities of purified yeast Alg2. Alg2-dependent Man3GlcNAc2-PDol production relied on net-neutral lipids with a propensity to form bilayers. We further showed addition of the α1,3- and α1,6-mannose can occur independently in either order but at differing rates. The conserved C-terminal EX7E motif, N-terminal cytosolic tail, and 3 G-rich loop motifs in Alg2 play crucial roles for these activities, both in vitro and in vivo. These findings provide insight into the unique bifunctionality of Alg2 during LLO synthesis and lead to a new model in which alternative, independent routes exist for Alg2 catalysis of the trimannosyl core oligosaccharide.-Li, S.-T., Wang, N., Xu, X.-X., Fujita, M., Nakanishi, H., Kitajima, T., Dean, N., Gao, X.-D. Alternative routes for synthesis of N-linked glycans by Alg2 mannosyltransferase.
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Affiliation(s)
- Sheng-Tao Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Ning Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Xin-Xin Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Morihisa Fujita
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Hideki Nakanishi
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Toshihiko Kitajima
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Neta Dean
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
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25
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O'Connor E, Töpf A, Zahedi RP, Spendiff S, Cox D, Roos A, Lochmüller H. Clinical and research strategies for limb-girdle congenital myasthenic syndromes. Ann N Y Acad Sci 2018; 1412:102-112. [PMID: 29315608 DOI: 10.1111/nyas.13520] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/05/2017] [Accepted: 09/12/2017] [Indexed: 12/21/2022]
Abstract
Congenital myasthenic syndromes (CMS) are a group of rare disorders that cause fatigable muscle weakness due to defective signal transmission at the neuromuscular junction, a specialized synapse between peripheral motor neurons and their target muscle fibers. There are now over 30 causative genes that have been reported for CMS. Of these, there are 10 that are associated with a limb-girdle pattern of muscle weakness and are thus classed as LG-CMS. Next-generation sequencing and advanced methods of data sharing are likely to uncover further genes that are associated with similar clinical phenotypes, contributing to better diagnosis and effective treatment of LG-CMS patients. This review highlights clinical and pathological hallmarks of LG-CMS in relation to the underlying genetic defects and pathways. Tailored animal and cell models are essential to elucidate the exact function and pathomechanisms at the neuromuscular synapse that underlie LG-CMS. The integration of genomics and proteomics data derived from these models and patients reveals new and often unexpected insights that are relevant beyond the rare genetic disorder of LG-CMS and may extend to the functioning of mammalian synapses in health and disease more generally.
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Affiliation(s)
- Emily O'Connor
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Ana Töpf
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - René P Zahedi
- Leibniz-Institut für Analytische Wissenschaften, ISAS e.V., Dortmund, Germany
| | - Sally Spendiff
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Daniel Cox
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Andreas Roos
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Leibniz-Institut für Analytische Wissenschaften, ISAS e.V., Dortmund, Germany
| | - Hanns Lochmüller
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
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26
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Schorling DC, Rost S, Lefeber DJ, Brady L, Müller CR, Korinthenberg R, Tarnopolsky M, Bönnemann CG, Rodenburg RJ, Bugiani M, Beytia M, Krüger M, van der Knaap M, Kirschner J. Early and lethal neurodegeneration with myasthenic and myopathic features: A new ALG14-CDG. Neurology 2017; 89:657-664. [PMID: 28733338 DOI: 10.1212/wnl.0000000000004234] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 04/28/2017] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVE To describe the presentation and identify the cause of a new clinical phenotype, characterized by early severe neurodegeneration with myopathic and myasthenic features. METHODS This case study of 5 patients from 3 families includes clinical phenotype, serial MRI, electrophysiologic testing, muscle biopsy, and full autopsy. Genetic workup included whole exome sequencing and segregation analysis of the likely causal mutation. RESULTS All 5 patients showed severe muscular hypotonia, progressive cerebral atrophy, and therapy-refractory epilepsy. Three patients had congenital contractures. All patients died during their first year of life. In 2 of our patients, electrophysiologic testing showed abnormal decrement, but treatment with pyridostigmine led only to temporary improvement. Causative mutations in ALG14 were identified in all patients. The mutation c.220 G>A (p.Asp74Asn) was homozygous in 2 patients and heterozygous in the other 3 patients. Additional heterozygous mutations were c.422T>G (p.Val141Gly) and c.326G>A (p.Arg109Gln). In all cases, parents were found to be heterozygous carriers. None of the identified variants has been described previously. CONCLUSIONS We report a genetic syndrome combining myasthenic features and severe neurodegeneration with therapy-refractory epilepsy. The underlying cause is a glycosylation defect due to mutations in ALG14. These cases broaden the phenotypic spectrum associated with ALG14 congenital disorders of glycosylation as previously only isolated myasthenia has been described.
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Affiliation(s)
- David C Schorling
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Simone Rost
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Dirk J Lefeber
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Lauren Brady
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Clemens R Müller
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Rudolf Korinthenberg
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Mark Tarnopolsky
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Carsten G Bönnemann
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Richard J Rodenburg
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Marianna Bugiani
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Maria Beytia
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Marcus Krüger
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Marjo van der Knaap
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Jan Kirschner
- From the Division of Neuropaediatrics and Muscle Disorders (D.C.S., R.K., M. Beytia, J.K.) and Center of Pediatric and Adolescent Medicine (M.K.), Faculty of Medicine, Medical Center, University of Freiburg; Department of Human Genetics (S.R., C.R.M., M. Beytia), Biozentrum, University of Würzburg, Germany; Department of Neurology, Translational Metabolic Laboratory, Donders Institute for Brain, Cognition and Behavior (D.J.L.), and Radboud Center for Mitochondrial Medicine, Department of Pediatrics (R.J.R.), Radboud University Medical Center, Nijmegen, the Netherlands; Department of Pediatrics (Neuromuscular and Neurometabolic Disorders) (L.B., M.T.), McMaster Children's Hospital, Hamilton, Canada; Neuromuscular and Neurogenetic Disorders of Childhood Section (C.G.B.), National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD; Departments of Child Neurology (M. Bugiani, M.v.d.K.) and Pathology (M. Bugiani), VU University Medical Center; and Department of Functional Genomics (M.v.d.K.), VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands.
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27
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Abstract
PurposePhosphoglucomutase-1 deficiency is a subtype of congenital disorders of glycosylation (PGM1-CDG). Previous casereports in PGM1-CDG patients receiving oral D-galactose (D-gal) showed clinical improvement. So far no systematic in vitro and clinical studies have assessed safety and benefits of D-gal supplementation. In a prospective pilot study, we evaluated the effects of oral D-gal in nine patients.MethodsD-gal supplementation was increased to 1.5 g/kg/day (maximum 50 g/day) in three increments over 18 weeks. Laboratory studies were performed before and during treatment to monitor safety and effect on serum transferrin-glycosylation, coagulation, and liver and endocrine function. Additionally, the effect of D-gal on cellular glycosylation was characterized in vitro.ResultsEight patients were compliant with D-gal supplementation. No adverse effects were reported. Abnormal baseline results (alanine transaminase, aspartate transaminase, activated partial thromboplastin time) improved or normalized already using 1 g/kg/day D-gal. Antithrombin-III levels and transferrin-glycosylation showed significant improvement, and increase in galactosylation and whole glycan content. In vitro studies before treatment showed N-glycan hyposialylation, altered O-linked glycans, abnormal lipid-linked oligosaccharide profile, and abnormal nucleotide sugars in patient fibroblasts. Most cellular abnormalities improved or normalized following D-gal treatment. D-gal increased both UDP-Glc and UDP-Gal levels and improved lipid-linked oligosaccharide fractions in concert with improved glycosylation in PGM1-CDG.ConclusionOral D-gal supplementation is a safe and effective treatment for PGM1-CDG in this pilot study. Transferrin glycosylation and ATIII levels were useful trial end points. Larger, longer-duration trials are ongoing.
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Maratha A, Colhoun HO, Knerr I, Coss KP, Doran P, Treacy EP. Classical Galactosaemia and CDG, the N-Glycosylation Interface. A Review. JIMD Rep 2016; 34:33-42. [PMID: 27502837 PMCID: PMC5509556 DOI: 10.1007/8904_2016_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 06/21/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022] Open
Abstract
Classical galactosaemia is a rare disorder of carbohydrate metabolism caused by galactose-1-phosphate uridyltransferase (GALT) deficiency (EC 2.7.7.12). The disease is life threatening if left untreated in neonates and the only available treatment option is a long-term galactose restricted diet. While this is lifesaving in the neonate, complications persist in treated individuals, and the cause of these, despite early initiation of treatment, and shared GALT genotypes remain poorly understood. Systemic abnormal glycosylation has been proposed to contribute substantially to the ongoing pathophysiology. The gross N-glycosylation assembly defects observed in the untreated neonate correct over time with treatment. However, N-glycosylation processing defects persist in treated children and adults.Congenital disorders of glycosylation (CDG) are a large group of over 100 inherited disorders affecting largely N- and O-glycosylation.In this review, we compare the clinical features observed in galactosaemia with a number of predominant CDG conditions.We also summarize the N-glycosylation abnormalities, which we have described in galactosaemia adult and paediatric patients, using an automated high-throughput HILIC-UPLC analysis of galactose incorporation into serum IgG with analysis of the corresponding N-glycan gene expression patterns and the affected pathways.
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Affiliation(s)
- Ashwini Maratha
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland
| | | | - Ina Knerr
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland
| | - Karen P Coss
- Faculty of Life Sciences and Medicine, Department of Infectious Diseases, King's College London, Guy's Hospital, London, UK
| | - Peter Doran
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland
| | - Eileen P Treacy
- National Centre for Inherited Metabolic Disorders, Children's University Hospital, Temple Street, Dublin, Ireland.
- University College Dublin Clinical Research Centre, Eccles Street, Dublin, Ireland.
- Trinity College, Dublin, Ireland.
- Mater Misericordiae University Hospital, Eccles Street, Dublin, Ireland.
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Bizzarri R, Cerbai E, Solaro R, Chiellini E. A Convenient Method for the Synthesis of (S)-Dolichol and (S)-Nordolichol. J BIOACT COMPAT POL 2016. [DOI: 10.1177/0883911503040435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A procedure for the preparation of (S)-dolichol and (S)-nor-dolichol starting from the polyprenyl fraction extracted from Gingko Biloba integer or extracted leaves is described. Two chiral isoprenoid compounds in good yields and high degree of enantiomeric excess were obtained. The (S)-nordolichol appears to be a good chiral precursor for the preparation of 14C-labeled (S)-dolichol which is to be used in investigations aimed at gaining further information with respect to the role of dolichol in the function of living cells.
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Affiliation(s)
| | | | | | - Emo Chiellini
- Department of Chemistry and Industrial Chemistry UdR of the Consortium INSTM University of Pisa via Risorgimento 35, 56123–Pisa, Italy
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30
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Ohno K, Ohkawara B, Ito M. Recent advances in congenital myasthenic syndromes. ACTA ACUST UNITED AC 2016. [DOI: 10.1111/cen3.12316] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Kinji Ohno
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Bisei Ohkawara
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
| | - Mikako Ito
- Division of Neurogenetics; Center for Neurological Diseases and Cancer; Nagoya University Graduate School of Medicine; Nagoya Japan
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Identification and characterization of transcriptional control region of the human beta 1,4-mannosyltransferase gene. Cytotechnology 2015; 69:417-434. [PMID: 26608959 DOI: 10.1007/s10616-015-9929-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022] Open
Abstract
All asparagine-linked glycans (N-glycans) on the eukaryotic glycoproteins are primarily derived from dolichol-linked oligosaccharides (DLO), synthesized on the rough endoplasmic reticulum membrane. We have previously reported cloning and identification of the human gene, HMT-1, which encodes chitobiosyldiphosphodolichol beta-mannosyltransferase (β1,4-MT) involved in the early assembly of DLO. Considering that N-glycosylation is one of the most ubiquitous post-translational modifications for many eukaryotic proteins, the HMT-1 could be postulated as one of the housekeeping genes, but its transcriptional regulation remains to be investigated. Here we screened a 1 kb region upstream from HMT-1 open reading frame (ORF) for transcriptionally regulatory sequences by using chloramphenicol acetyl transferase (CAT) assay, and found that the region from -33 to -1 positions might act in HMT-1 transcription at basal level and that the region from -200 to -42 should regulate its transcription either positively or negatively. In addition, results with CAT assays suggested the possibility that two GATA-1 motifs and an Sp1 motif within a 200 bp region upstream from HMT-1 ORF might significantly upregulate HMT-1 transcription. On the contrary, the observations obtained from site-directed mutational analyses revealed that an NF-1/AP-2 overlapping motif located at -148 to -134 positions should serve as a strong silencer. The control of the HMT-1 transcription by these motifs resided within the 200 bp region could partially explain the variation of expression level among various human tissues, suggesting availability and importance of this region for regulatory role in HMT-1 expression.
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Renaud J, Dumont F, Khelfaoui M, Foisset S, Letourneur F, Bienvenu T, Khwaja O, Dorseuil O, Billuart P. Identification of intellectual disability genes showing circadian clock-dependent expression in the mouse hippocampus. Neuroscience 2015; 308:11-50. [DOI: 10.1016/j.neuroscience.2015.08.066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 08/24/2015] [Accepted: 08/26/2015] [Indexed: 10/23/2022]
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Li X, Raihan MA, Reynoso FJ, He M. Glycosylation Analysis for Congenital Disorders of Glycosylation. ACTA ACUST UNITED AC 2015; 86:17.18.1-17.18.22. [PMID: 26132001 DOI: 10.1002/0471142905.hg1718s86] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Congenital disorders of glycosylation (CDG) are a group of diseases with highly variable phenotypes and inconsistent clinical features. Since the first description of a CDG in 1980, approximately 100 disorders have been identified. Most of these are defects in protein glycosylation, although an increasing number are defects of glycolipid or proteoglycan biosynthesis. A group of biochemical markers has been used to characterize protein glycosylation abnormalities in CDG. This unit describes three protocols that can be used to measure plasma or serum carbohydrate deficient transferrin (CDT) profile, N-glycan profile, and O-glycan profile by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) or liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS). The quantification of particular biomarkers, such as T antigens or sialylated T antigens, could also be achieved by liquid chromatography-tandem mass spectrometry (LC-MS/MS). These techniques can be used to identify a majority of patients with defects in protein glycosylation, although different techniques, such as flow cytometry with immunostaining, are necessary to detect defects in glycolipid or proteoglycan biosynthesis which is not included in this unit.
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Affiliation(s)
- Xueli Li
- Palmieri Metabolic Disease Laboratory, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Mohd A Raihan
- Palmieri Metabolic Disease Laboratory, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | | | - Miao He
- Palmieri Metabolic Disease Laboratory, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Harada Y, Hirayama H, Suzuki T. Generation and degradation of free asparagine-linked glycans. Cell Mol Life Sci 2015; 72:2509-33. [PMID: 25772500 PMCID: PMC11113800 DOI: 10.1007/s00018-015-1881-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/19/2015] [Accepted: 03/05/2015] [Indexed: 10/23/2022]
Abstract
Asparagine (N)-linked protein glycosylation, which takes place in the eukaryotic endoplasmic reticulum (ER), is important for protein folding, quality control and the intracellular trafficking of secretory and membrane proteins. It is known that, during N-glycosylation, considerable amounts of lipid-linked oligosaccharides (LLOs), the glycan donor substrates for N-glycosylation, are hydrolyzed to form free N-glycans (FNGs) by unidentified mechanisms. FNGs are also generated in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins during ER-associated degradation. FNGs derived from LLOs and misfolded glycoproteins are eventually merged into one pool in the cytosol and the various glycan structures are processed to a near homogenous glycoform. This article summarizes the current state of our knowledge concerning the formation and catabolism of FNGs.
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Affiliation(s)
- Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Hiroto Hirayama
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
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35
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Inherited disorders of the neuromuscular junction: an update. J Neurol 2014; 261:2234-43. [PMID: 25305004 DOI: 10.1007/s00415-014-7520-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 10/24/2022]
Abstract
Congenital myasthenic syndromes (CMSs) are a group of heterogeneous inherited disorders caused by mutations in genes affecting the function and structure of the neuromuscular junction. This review updates the reader on established and novel subtypes of congenital myasthenia, and the treatment strategies for these increasingly heterogeneous disorders. The discovery of mutations associated with the N-glycosylation pathway and in the family of serine peptidases has shown that causative genes encoding ubiquitously expressed molecules can produce defects at the human neuromuscular junction. By contrast, mutations in lipoprotein-like receptor 4 (LRP4), a long-time candidate gene for congenital myasthenia, and a novel phenotype of myasthenia with distal weakness and atrophy due to mutations in AGRN have now been described. In addition, a pathogenic splicing mutation in a nonfunctional exon of CHRNA1 has been reported emphasizing the importance of analysing nonfunctional exons in genetic analysis. The benefit of salbutamol and ephedrine alone or combined with pyridostigmine or 3,4-DAP is increasingly being reported for particular subtypes of CMS.
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36
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37
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Baycin-Hizal D, Gottschalk A, Jacobson E, Mai S, Wolozny D, Zhang H, Krag SS, Betenbaugh MJ. Physiologic and pathophysiologic consequences of altered sialylation and glycosylation on ion channel function. Biochem Biophys Res Commun 2014; 453:243-53. [PMID: 24971539 DOI: 10.1016/j.bbrc.2014.06.067] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/13/2014] [Indexed: 01/01/2023]
Abstract
Voltage-gated ion channels are transmembrane proteins that regulate electrical excitability in cells and are essential components of the electrically active tissues of nerves, muscle and the heart. Potassium channels are one of the largest subfamilies of voltage sensitive channels and are among the most-studied of the voltage-gated ion channels. Voltage-gated channels can be glycosylated and changes in the glycosylation pattern can affect ion channel function, leading to neurological and neuromuscular disorders and congenital disorders of glycosylation (CDG). Alterations in glycosylation can also be acquired and appear to play a role in development and aging. Recent studies have focused on the impact of glycosylation and sialylation on ion channels, particularly for voltage-gated potassium and sodium channels. The terminal step of sialylation often affects channel activation and inactivation kinetics. The presence of sialic acids on O or N-glycans can alter the gating mechanism and cause conformational changes in the voltage-sensing domains due to sialic acid's negative charges. This manuscript will provide an overview of sialic acids, potassium and sodium channel function, and the impact of sialylation on channel activation and deactivation.
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Affiliation(s)
- Deniz Baycin-Hizal
- Chemical and Biomolecular Engineering, Johns Hopkins University, United States.
| | - Allan Gottschalk
- Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, United States
| | - Elena Jacobson
- Chemical and Biomolecular Engineering, Johns Hopkins University, United States
| | - Sunny Mai
- Chemical and Biomolecular Engineering, Johns Hopkins University, United States
| | - Daniel Wolozny
- Chemical and Biomolecular Engineering, Johns Hopkins University, United States
| | - Hui Zhang
- Pathology, Johns Hopkins University, United States
| | - Sharon S Krag
- Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, United States
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38
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Suzuki T, Harada Y. Non-lysosomal degradation pathway for N-linked glycans and dolichol-linked oligosaccharides. Biochem Biophys Res Commun 2014; 453:213-9. [PMID: 24866240 DOI: 10.1016/j.bbrc.2014.05.075] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/16/2014] [Indexed: 01/11/2023]
Abstract
There is growing evidence that asparagine (N)-linked glycans play pivotal roles in protein folding and intra- or intercellular trafficking of N-glycosylated proteins. During the N-glycosylation of proteins, significant amounts of free oligosaccharides (fOSs) and phosphorylated oligosaccharides (POSs) are generated at the endoplasmic reticulum (ER) membrane by unclarified mechanisms. fOSs are also formed in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins destined for proteasomal degradation. This article summarizes the current knowledge of the molecular and regulatory mechanisms underlying the formation of fOSs and POSs in mammalian cells and Saccharomyces cerevisiae.
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Affiliation(s)
- Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Japan.
| | - Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Japan
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Abstract
PURPOSE OF REVIEW Congenital myasthenic syndromes (CMSs) form a heterogeneous group of genetic diseases characterized by a dysfunction of neuromuscular transmission because of mutations in numerous genes. This review will focus on the causative genes recently identified and on the therapy of CMSs. RECENT FINDINGS Advances in exome sequencing allowed the discovery of a new group of genes that did not code for the known molecular components of the neuromuscular junction, and the definition of a new group of glycosylation-defective CMS. Rather than the specific drugs used, some of them having been known for decades, it is the rigorous therapeutic strategy that is now offered to the patient in relation to the identified mutated gene that is novel and promising. SUMMARY In addition to the above main points, we also present new data on the genes that were already known with an emphasis on the clinic and on animal models that may be of use to understand the pathophysiology of the disease. We also stress not only the diagnosis difficulties between congenital myopathies and CMSs, but also the continuum that may exist between the two.
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40
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Monies DM, Al-Hindi HN, Al-Muhaizea MA, Jaroudi DJ, Al-Younes B, Naim EA, Wakil SM, Meyer BF, Bohlega S. Clinical and pathological heterogeneity of a congenital disorder of glycosylation manifesting as a myasthenic/myopathic syndrome. Neuromuscul Disord 2014; 24:353-9. [DOI: 10.1016/j.nmd.2013.12.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 12/07/2013] [Accepted: 12/24/2013] [Indexed: 01/05/2023]
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41
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Wolfe LA, Krasnewich D. Congenital disorders of glycosylation and intellectual disability. ACTA ACUST UNITED AC 2014; 17:211-25. [PMID: 23798010 DOI: 10.1002/ddrr.1115] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2012] [Indexed: 12/31/2022]
Abstract
The congenital disorders of glycosylation (CDG) are a rapidly growing group of inborn errors of metabolism that result from defects in the synthesis of glycans. Glycosylation is a major post-translational protein modification and an estimated 2% of the human genome encodes proteins for glycosylation. The molecular bases for the current 60 disorders, affecting approximately 800 individuals, have been identified, many in the last 5 years. CDG should be considered in any multi-system syndrome or single tissue disorder not explained by the identification of another disorder. The initial clinical presentation varies significantly among individuals, even between affected siblings. However, two thirds of the known CDGs are associated with intellectual disabilities and most affected individuals need support services throughout their lives. Additional disorders of glycosylation are likely to be characterized over time.
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Affiliation(s)
- Lynne A Wolfe
- Genetic Nurse Practitioner, Undiagnosed Diseases Program, National Human Genome Research Institute, Bethesda, Maryland 20892, USA.
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42
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Imamura K, Maeda S, Kawamura I, Matsuyama K, Shinohara N, Yahiro Y, Nagano S, Setoguchi T, Yokouchi M, Ishidou Y, Komiya S. Human immunodeficiency virus type 1 enhancer-binding protein 3 is essential for the expression of asparagine-linked glycosylation 2 in the regulation of osteoblast and chondrocyte differentiation. J Biol Chem 2014; 289:9865-79. [PMID: 24563464 DOI: 10.1074/jbc.m113.520585] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Human immunodeficiency virus type 1 enhancer-binding protein 3 (Hivep3) suppresses osteoblast differentiation by inducing proteasomal degradation of the osteogenesis master regulator Runx2. In this study, we tested the possibility of cooperation of Hivep1, Hivep2, and Hivep3 in osteoblast and/or chondrocyte differentiation. Microarray analyses with ST-2 bone stroma cells demonstrated that expression of any known osteochondrogenesis-related genes was not commonly affected by the three Hivep siRNAs. Only Hivep3 siRNA promoted osteoblast differentiation in ST-2 cells, whereas all three siRNAs cooperatively suppressed differentiation in ATDC5 chondrocytes. We further used microarray analysis to identify genes commonly down-regulated in both MC3T3-E1 osteoblasts and ST-2 cells upon knockdown of Hivep3 and identified asparagine-linked glycosylation 2 (Alg2), which encodes a mannosyltransferase residing on the endoplasmic reticulum. The Hivep3 siRNA-mediated promotion of osteoblast differentiation was negated by forced Alg2 expression. Alg2 suppressed osteoblast differentiation and bone formation in cultured calvarial bone. Alg2 was immunoprecipitated with Runx2, whereas the combined transfection of Runx2 and Alg2 interfered with Runx2 nuclear localization, which resulted in suppression of Runx2 activity. Chondrocyte differentiation was promoted by Hivep3 overexpression, in concert with increased expression of Creb3l2, whose gene product is the endoplasmic reticulum stress transducer crucial for chondrogenesis. Alg2 silencing suppressed Creb3l2 expression and chondrogenesis of ATDC5 cells, whereas infection of Alg2-expressing virus promoted chondrocyte maturation in cultured cartilage rudiments. Thus, Alg2, as a downstream mediator of Hivep3, suppresses osteogenesis, whereas it promotes chondrogenesis. To our knowledge, this study is the first to link a mannosyltransferase gene to osteochondrogenesis.
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Cao L, Yu L, Guo Z, Shen A, Guo Y, Liang X. N-Glycosylation Site Analysis of Proteins from Saccharomyces cerevisiae by Using Hydrophilic Interaction Liquid Chromatography-Based Enrichment, Parallel Deglycosylation, and Mass Spectrometry. J Proteome Res 2014; 13:1485-93. [DOI: 10.1021/pr401049e] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Liwei Cao
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Long Yu
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhimou Guo
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Aijin Shen
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yunü Guo
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xinmiao Liang
- Key Laboratory of Separation
Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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Metabolically programmed quality control system for dolichol-linked oligosaccharides. Proc Natl Acad Sci U S A 2013; 110:19366-71. [PMID: 24218558 DOI: 10.1073/pnas.1312187110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The glycolipid Glc3Man9GlcNAc2-pyrophosphate-dolichol serves as the precursor for asparagine (N)-linked protein glycosylation in mammals. The biosynthesis of dolichol-linked oligosaccharides (DLOs) is arrested in low-glucose environments via unknown mechanisms, resulting in abnormal N-glycosylation. Here, we show that under glucose deprivation, DLOs are prematurely degraded during the early stages of DLO biosynthesis by pyrophosphatase, leading to the release of singly phosphorylated oligosaccharides into the cytosol. We identified that the level of GDP-mannose (Man), which serves as a donor substrate for DLO biosynthesis, is substantially reduced under glucose deprivation. We provide evidence that the selective shutdown of the GDP-Man biosynthetic pathway is sufficient to induce the release of phosphorylated oligosaccharides. These results indicate that glucose-regulated metabolic changes in the GDP-Man biosynthetic pathway cause the biosynthetic arrest of DLOs and facilitate their premature degradation by pyrophosphatase. We propose that this degradation system may avoid abnormal N-glycosylation with premature oligosaccharides under conditions that impair efficient DLO biosynthesis.
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de Las Heras JI, Meinke P, Batrakou DG, Srsen V, Zuleger N, Kerr AR, Schirmer EC. Tissue specificity in the nuclear envelope supports its functional complexity. Nucleus 2013; 4:460-77. [PMID: 24213376 PMCID: PMC3925691 DOI: 10.4161/nucl.26872] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Nuclear envelope links to inherited disease gave the conundrum of how mutations in near-ubiquitous proteins can yield many distinct pathologies, each focused in different tissues. One conundrum-resolving hypothesis is that tissue-specific partner proteins mediate these pathologies. Such partner proteins may have now been identified with recent proteome studies determining nuclear envelope composition in different tissues. These studies revealed that the majority of the total nuclear envelope proteins are tissue restricted in their expression. Moreover, functions have been found for a number these tissue-restricted nuclear envelope proteins that fit with mechanisms proposed to explain how the nuclear envelope could mediate disease, including defects in mechanical stability, cell cycle regulation, signaling, genome organization, gene expression, nucleocytoplasmic transport, and differentiation. The wide range of functions to which these proteins contribute is consistent with not only their involvement in tissue-specific nuclear envelope disease pathologies, but also tissue evolution.
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Affiliation(s)
- Jose I de Las Heras
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Peter Meinke
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Dzmitry G Batrakou
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Vlastimil Srsen
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Nikolaj Zuleger
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Alastair Rw Kerr
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
| | - Eric C Schirmer
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology; University of Edinburgh; Edinburgh, UK
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Kirchmaier S, Höckendorf B, Möller EK, Bornhorst D, Spitz F, Wittbrodt J. Efficient site-specific transgenesis and enhancer activity tests in medaka using PhiC31 integrase. Development 2013; 140:4287-95. [PMID: 24048591 PMCID: PMC3809364 DOI: 10.1242/dev.096081] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Established transgenesis methods for fish model systems allow efficient genomic integration of transgenes. However, thus far a way of controlling copy number and integration sites has not been available, leading to variable transgene expression caused by position effects. The integration of transgenes at predefined genomic positions enables the direct comparison of different transgenes, thereby improving time and cost efficiency. Here, we report an efficient PhiC31-based site-specific transgenesis system for medaka. This system includes features that allow the pre-selection of successfully targeted integrations early on in the injected generation. Pre-selected embryos transmit the correctly integrated transgene through the germline with high efficiency. The landing site design enables a variety of applications, such as reporter and enhancer switch, in addition to the integration of any insert. Importantly, this allows assaying of enhancer activity in a site-specific manner without requiring germline transmission, thus speeding up large-scale analyses of regulatory elements.
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Affiliation(s)
- Stephan Kirchmaier
- Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
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Ezgu F, Krejci P, Li S, de Sousa C, Graham JM, Hansmann I, He W, Porpora K, Wand D, Wertelecki W, Schneider A, Wilcox WR. Phenotype-genotype correlations in patients with Marinesco-Sjögren syndrome. Clin Genet 2013; 86:74-84. [PMID: 23829326 DOI: 10.1111/cge.12230] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 07/02/2013] [Accepted: 07/02/2013] [Indexed: 12/17/2022]
Abstract
Marinesco-Sjögren syndrome (MSS; MIM 248800) is an autosomal recessive disorder characterized by congenital cerebellar ataxia, early cataracts, developmental delay, myopathy and short stature. Alterations in the gene SIL1 cause MSS in some patients with typical findings. In this study, molecular investigations including sequencing of the SIL1 gene, western blotting and microscopic investigations in fibroblast cultures were carried out in a cohort of 15 patients from 14 unrelated families, including the large, inbred family reported by Superneau et al., having the clinical features of MSS to provide insights into the pathophysiology of the disorder. A total of seven different mutations were found in eight of the patients from seven families. The mutations caused loss of the BIP-associated protein (BAP) protein in four patients by western blot. Novel clinical features such as dental abnormalities, iris coloboma, eczema and hormonal abnormalities were noticed in some patients, but there was no clear way to distinguish those with and without SIL1 mutations. Cultured fibroblasts contained numerous cytoplasmic inclusion bodies, similar to those identified in the brain of the whoozy mouse in five unrelated patients, three with and two without SIL1 mutations, suggesting some SIL1 negative patients share a common cellular pathogenesis with those who are SIL1 positive.
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Affiliation(s)
- F Ezgu
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Department of Pediatric Metabolic Disorders and Pediatric Genetics, Gazi University Faculty of Medicine, Ankara, Turkey
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48
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Houlden H. Defective N-linked protein glycosylation pathway in congenital myasthenic syndromes. Brain 2013; 136:692-5. [PMID: 23436500 DOI: 10.1093/brain/awt042] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Cossins J, Belaya K, Hicks D, Salih MA, Finlayson S, Carboni N, Liu WW, Maxwell S, Zoltowska K, Farsani GT, Laval S, Seidhamed MZ, Donnelly P, Bentley D, McGowan SJ, Müller J, Palace J, Lochmüller H, Beeson D. Congenital myasthenic syndromes due to mutations in ALG2 and ALG14. Brain 2013; 136:944-56. [PMID: 23404334 PMCID: PMC3580273 DOI: 10.1093/brain/awt010] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 12/13/2012] [Accepted: 12/19/2012] [Indexed: 01/22/2023] Open
Abstract
Congenital myasthenic syndromes are a heterogeneous group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. We performed linkage analysis, whole-exome and whole-genome sequencing to determine the underlying defect in patients with an inherited limb-girdle pattern of myasthenic weakness. We identify ALG14 and ALG2 as novel genes in which mutations cause a congenital myasthenic syndrome. Through analogy with yeast, ALG14 is thought to form a multiglycosyltransferase complex with ALG13 and DPAGT1 that catalyses the first two committed steps of asparagine-linked protein glycosylation. We show that ALG14 is concentrated at the muscle motor endplates and small interfering RNA silencing of ALG14 results in reduced cell-surface expression of muscle acetylcholine receptor expressed in human embryonic kidney 293 cells. ALG2 is an alpha-1,3-mannosyltransferase that also catalyses early steps in the asparagine-linked glycosylation pathway. Mutations were identified in two kinships, with mutation ALG2p.Val68Gly found to severely reduce ALG2 expression both in patient muscle, and in cell cultures. Identification of DPAGT1, ALG14 and ALG2 mutations as a cause of congenital myasthenic syndrome underscores the importance of asparagine-linked protein glycosylation for proper functioning of the neuromuscular junction. These syndromes form part of the wider spectrum of congenital disorders of glycosylation caused by impaired asparagine-linked glycosylation. It is likely that further genes encoding components of this pathway will be associated with congenital myasthenic syndromes or impaired neuromuscular transmission as part of a more severe multisystem disorder. Our findings suggest that treatment with cholinesterase inhibitors may improve muscle function in many of the congenital disorders of glycosylation.
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Affiliation(s)
- Judith Cossins
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
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50
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Matthijs G, Rymen D, Millón MBB, Souche E, Race V. Approaches to homozygosity mapping and exome sequencing for the identification of novel types of CDG. Glycoconj J 2012; 30:67-76. [PMID: 22983704 DOI: 10.1007/s10719-012-9445-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 12/18/2022]
Abstract
In the past decade, the identification of most genes involved in Congenital Disorders of Glycosylation (CDG) (type I) was achieved by a combination of biochemical, cell biological and glycobiological investigations. This has been truly successful for CDG-I, because the candidate genes could be selected on the basis of the homology of the synthetic pathway of the dolichol linked oligosaccharide in human and yeast. On the contrary, only a few CDG-II defects were elucidated, be it that some of the discoveries represent wonderful breakthroughs, like e.g, the identification of the COG defects. In general, many rare genetic defects have been identified by positional cloning. However, only a few types of CDG have effectively been elucidated by linkage analysis and so-called reverse genetics. The reason is that the families were relatively small and could-except for CDG-PMM2-not be pooled for analysis. Hence, a large number of CDG cases has long remained unsolved because the search for the culprit gene was very laborious, due to the heterogeneous phenotype and the myriad of candidate defects. This has changed when homozygosity mapping came of age, because it could be applied to small (consanguineous) families. Many novel CDG genes have been discovered in this way. But the best has yet to come: what we are currently witnessing, is an explosion of novel CDG defects, thanks to exome sequencing: seven novel types were published over a period of only two years. It is expected that exome sequencing will soon become a diagnostic tool, that will continuously uncover new facets of this fascinating group of diseases.
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Affiliation(s)
- Gert Matthijs
- Center for Human Genetics, University of Leuven, Herestraat 49, 3000, Leuven, Belgium.
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