1
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Tan RL, Sciandra F, Hübner W, Bozzi M, Reimann J, Schoch S, Brancaccio A, Blaess S. The missense mutation C667F in murine β-dystroglycan causes embryonic lethality, myopathy and blood-brain barrier destabilization. Dis Model Mech 2024; 17:dmm050594. [PMID: 38616731 DOI: 10.1242/dmm.050594] [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: 11/10/2023] [Accepted: 04/08/2024] [Indexed: 04/16/2024] Open
Abstract
Dystroglycan (DG) is an extracellular matrix receptor consisting of an α- and a β-DG subunit encoded by the DAG1 gene. The homozygous mutation (c.2006G>T, p.Cys669Phe) in β-DG causes muscle-eye-brain disease with multicystic leukodystrophy in humans. In a mouse model of this primary dystroglycanopathy, approximately two-thirds of homozygous embryos fail to develop to term. Mutant mice that are born undergo a normal postnatal development but show a late-onset myopathy with partially penetrant histopathological changes and an impaired performance on an activity wheel. Their brains and eyes are structurally normal, but the localization of mutant β-DG is altered in the glial perivascular end-feet, resulting in a perturbed protein composition of the blood-brain and blood-retina barrier. In addition, α- and β-DG protein levels are significantly reduced in muscle and brain of mutant mice. Owing to the partially penetrant developmental phenotype of the C669F β-DG mice, they represent a novel and highly valuable mouse model with which to study the molecular effects of β-DG functional alterations both during embryogenesis and in mature muscle, brain and eye, and to gain insight into the pathogenesis of primary dystroglycanopathies.
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Affiliation(s)
- Rui Lois Tan
- Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Francesca Sciandra
- Institute of Chemical Sciences and Technologies 'Giulio Natta' (SCITEC)-CNR, 00168 Rome, Italy
| | - Wolfgang Hübner
- Biomolecular Photonics, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Manuela Bozzi
- Institute of Chemical Sciences and Technologies 'Giulio Natta' (SCITEC)-CNR, 00168 Rome, Italy
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie. Sezione di Biochimica. Università Cattolica del Sacro Cuore di Roma, 00168 Rome, Italy
| | - Jens Reimann
- Department of Neurology, Neuromuscular Diseases Section, University Hospital Bonn, 53127 Bonn, Germany
| | - Susanne Schoch
- Synaptic Neuroscience Team, Institute of Neuropathology, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Andrea Brancaccio
- Institute of Chemical Sciences and Technologies 'Giulio Natta' (SCITEC)-CNR, 00168 Rome, Italy
- School of Biochemistry, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Sandra Blaess
- Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Medical Faculty, University of Bonn, 53127 Bonn, Germany
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2
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Hord JM, Anderson ME, Prouty SJ, Melton S, Gastel Z, Zimmerman K, Weiss RM, Campbell KP. Matriglycan maintains t-tubule structural integrity in cardiac muscle. Proc Natl Acad Sci U S A 2024; 121:e2402890121. [PMID: 38771868 PMCID: PMC11145246 DOI: 10.1073/pnas.2402890121] [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: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 05/23/2024] Open
Abstract
Maintaining the structure of cardiac membranes and membrane organelles is essential for heart function. A critical cardiac membrane organelle is the transverse tubule system (called the t-tubule system) which is an invagination of the surface membrane. A unique structural characteristic of the cardiac muscle t-tubule system is the extension of the extracellular matrix (ECM) from the surface membrane into the t-tubule lumen. However, the importance of the ECM extending into the cardiac t-tubule lumen is not well understood. Dystroglycan (DG) is an ECM receptor in the surface membrane of many cells, and it is also expressed in t-tubules in cardiac muscle. Extensive posttranslational processing and O-glycosylation are required for DG to bind ECM proteins and the binding is mediated by a glycan structure known as matriglycan. Genetic disruption resulting in defective O-glycosylation of DG results in muscular dystrophy with cardiorespiratory pathophysiology. Here, we show that DG is essential for maintaining cardiac t-tubule structural integrity. Mice with defects in O-glycosylation of DG developed normal t-tubules but were susceptible to stress-induced t-tubule loss or severing that contributed to cardiac dysfunction and disease progression. Finally, we observed similar stress-induced cardiac t-tubule disruption in a cohort of mice that solely lacked matriglycan. Collectively, our data indicate that DG in t-tubules anchors the luminal ECM to the t-tubule membrane via the polysaccharide matriglycan, which is critical to transmitting structural strength of the ECM to the t-tubules and provides resistance to mechanical stress, ultimately preventing disruptions in cardiac t-tubule integrity.
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Affiliation(s)
- Jeffrey M. Hord
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Mary E. Anderson
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Sally J. Prouty
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Shelly Melton
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Zeita Gastel
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Kathy Zimmerman
- Division of Cardiology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA52242
| | - Robert M. Weiss
- Division of Cardiology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Abboud Cardiovascular Research Center, Carver College of Medicine, Department of Internal Medicine-Cardiovascular Medicine, University of Iowa, Iowa City, IA52242
- Iowa City Veterans Affairs Health Care System, University of Iowa, Iowa City, IA52242
| | - Kevin P. Campbell
- HHMI, University of Iowa, Iowa City, IA52242
- Senator Paul D. Wellstone Muscular Dystrophy Specialized Research Center, University of Iowa, Iowa City, IA52242
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA52242
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3
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Karas BF, Terez KR, Mowla S, Battula N, Flannery KP, Gural BM, Aboussleman G, Mubin N, Manzini MC. Removal of pomt1 in zebrafish leads to loss of α-dystroglycan glycosylation and dystroglycanopathy phenotypes. Hum Mol Genet 2024; 33:709-723. [PMID: 38272461 PMCID: PMC11000664 DOI: 10.1093/hmg/ddae006] [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: 07/11/2023] [Revised: 11/28/2023] [Accepted: 12/22/2023] [Indexed: 01/27/2024] Open
Abstract
Biallelic mutations in Protein O-mannosyltransferase 1 (POMT1) are among the most common causes of a severe group of congenital muscular dystrophies (CMDs) known as dystroglycanopathies. POMT1 is a glycosyltransferase responsible for the attachment of a functional glycan mediating interactions between the transmembrane glycoprotein dystroglycan and its binding partners in the extracellular matrix (ECM). Disruptions in these cell-ECM interactions lead to multiple developmental defects causing brain and eye malformations in addition to CMD. Removing Pomt1 in the mouse leads to early embryonic death due to the essential role of dystroglycan during placental formation in rodents. Here, we characterized and validated a model of pomt1 loss of function in the zebrafish showing that developmental defects found in individuals affected by dystroglycanopathies can be recapitulated in the fish. We also discovered that pomt1 mRNA provided by the mother in the oocyte supports dystroglycan glycosylation during the first few weeks of development. Muscle disease, retinal synapse formation deficits, and axon guidance defects can only be uncovered during the first week post fertilization by generating knock-out embryos from knock-out mothers. Conversely, maternal pomt1 from heterozygous mothers was sufficient to sustain muscle, eye, and brain development only leading to loss of photoreceptor synapses at 30 days post fertilization. Our findings show that it is important to define the contribution of maternal mRNA while developing zebrafish models of dystroglycanopathies and that offspring generated from heterozygous and knock-out mothers can be used to differentiate the role of dystroglycan glycosylation in tissue formation and maintenance.
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Affiliation(s)
- Brittany F Karas
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Kristin R Terez
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Shorbon Mowla
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Namarata Battula
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Kyle P Flannery
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Brian M Gural
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Grace Aboussleman
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Numa Mubin
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - M Chiara Manzini
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
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4
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Turi M, Anilkumar Sithara A, Hofmanová L, Žihala D, Radhakrishnan D, Vdovin A, Knápková S, Ševčíková T, Chyra Z, Jelínek T, Šimíček M, Gullà A, Anderson KC, Hájek R, Hrdinka M. Transcriptome Analysis of Diffuse Large B-Cell Lymphoma Cells Inducibly Expressing MyD88 L265P Mutation Identifies Upregulated CD44, LGALS3, NFKBIZ, and BATF as Downstream Targets of Oncogenic NF-κB Signaling. Int J Mol Sci 2023; 24:ijms24065623. [PMID: 36982699 PMCID: PMC10057398 DOI: 10.3390/ijms24065623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
During innate immune responses, myeloid differentiation primary response 88 (MyD88) functions as a critical signaling adaptor protein integrating stimuli from toll-like receptors (TLR) and the interleukin-1 receptor (IL-1R) family and translates them into specific cellular outcomes. In B cells, somatic mutations in MyD88 trigger oncogenic NF-κB signaling independent of receptor stimulation, which leads to the development of B-cell malignancies. However, the exact molecular mechanisms and downstream signaling targets remain unresolved. We established an inducible system to introduce MyD88 to lymphoma cell lines and performed transcriptomic analysis (RNA-seq) to identify genes differentially expressed by MyD88 bearing the L265P oncogenic mutation. We show that MyD88L265P activates NF-κB signaling and upregulates genes that might contribute to lymphomagenesis, including CD44, LGALS3 (coding Galectin-3), NFKBIZ (coding IkBƺ), and BATF. Moreover, we demonstrate that CD44 can serve as a marker of the activated B-cell (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) and that CD44 expression is correlated with overall survival in DLBCL patients. Our results shed new light on the downstream outcomes of MyD88L265P oncogenic signaling that might be involved in cellular transformation and provide novel therapeutical targets.
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Affiliation(s)
- Marcello Turi
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Anjana Anilkumar Sithara
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Lucie Hofmanová
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - David Žihala
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Dhwani Radhakrishnan
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Alexander Vdovin
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Sofija Knápková
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Tereza Ševčíková
- Faculty of Science, University of Ostrava, 70100 Ostrava, Czech Republic
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Zuzana Chyra
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Tomáš Jelínek
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Michal Šimíček
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Annamaria Gullà
- Candiolo Cancer Institute, FPO-IRCCS, 10060 Candiolo, Italy
- Jerome Lipper Multiple Myeloma Center, LeBow Institute for Myeloma Therapeutics, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02215, USA
| | - Kenneth Carl Anderson
- Jerome Lipper Multiple Myeloma Center, LeBow Institute for Myeloma Therapeutics, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02215, USA
| | - Roman Hájek
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
| | - Matouš Hrdinka
- Department of Haematooncology, Faculty of Medicine, University of Ostrava, 70300 Ostrava, Czech Republic
- Department of Haematooncology, University Hospital Ostrava, 70800 Ostrava, Czech Republic
- Correspondence:
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5
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Canse C, Yildirim E, Yaba A. Overview of junctional complexes during mammalian early embryonic development. Front Endocrinol (Lausanne) 2023; 14:1150017. [PMID: 37152932 PMCID: PMC10158982 DOI: 10.3389/fendo.2023.1150017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/28/2023] [Indexed: 05/09/2023] Open
Abstract
Cell-cell junctions form strong intercellular connections and mediate communication between blastomeres during preimplantation embryonic development and thus are crucial for cell integrity, polarity, cell fate specification and morphogenesis. Together with cell adhesion molecules and cytoskeletal elements, intercellular junctions orchestrate mechanotransduction, morphokinetics and signaling networks during the development of early embryos. This review focuses on the structure, organization, function and expressional pattern of the cell-cell junction complexes during early embryonic development. Understanding the importance of dynamic junction formation and maturation processes will shed light on the molecular mechanism behind developmental abnormalities of early embryos during the preimplantation period.
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Affiliation(s)
- Ceren Canse
- Faculty of Medicine, Yeditepe University, Istanbul, Türkiye
| | - Ecem Yildirim
- Department of Histology and Embryology, Yeditepe University Faculty of Medicine, Istanbul, Türkiye
| | - Aylin Yaba
- Department of Histology and Embryology, Yeditepe University Faculty of Medicine, Istanbul, Türkiye
- *Correspondence: Aylin Yaba,
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6
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Matsuo I, Kimura-Yoshida C, Ueda Y. Developmental and mechanical roles of Reichert's membrane in mouse embryos. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210257. [PMID: 36252218 PMCID: PMC9574627 DOI: 10.1098/rstb.2021.0257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/24/2022] [Indexed: 12/23/2022] Open
Abstract
Embryonic development and growth in placental mammals proceeds in utero with the support of exchanges of gases, nutrients and waste products between maternal tissues and offspring. Murine embryos are surrounded by several extraembryonic membranes, parietal and visceral yolk sacs, and amnion in the uterus. Notably, the parietal yolk sac is the most outer membrane, consists of three layers, trophoblasts and parietal endoderm (PaE) cells, and is separated by a thick basal lamina termed Reichert's membrane (RM). RM is composed of extracellular matrix (ECM) initially formed as the basement membrane of the trophectoderm of pre-implanted embryos and followed by the heavy deposition of ECM mainly produced in PaE cells of post-implanted embryos. In addition to the physiological roles of RM, such as gas and nutrient exchange, it also plays a crucial role in cushioning and dispersing intrauterine pressures exerted on embryos for normal egg-cylinder morphogenesis. Mechanistically, such intrauterine pressures generated by uterine smooth muscle contractions appear to be involved in the elongation of the egg-cylinder shape, along with primary axis formation, as an important biomechanical element in utero. This review focuses on our current views of the roles of RM in properly buffering intrauterine mechanical forces for mouse egg-cylinder morphogenesis. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
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Grants
- Takeda Science Foundation
- a grant-in-aid for challenging Research(Exploratory)from the Ministry of Education, Culture, Sports, Science, and Technology, Japan
- from the Ministry a grant-in-aid for Scientific Research (C) of Education, Culture, Sports, Science, and Technology, Japan
- a grant-in-aid for Transformative Research Areas (A)from the Ministry of Education, Culture, Sports, Science, and Technology, Japan
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Affiliation(s)
- Isao Matsuo
- Department of Molecular Embryology, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840, Murodo-cho, Izumi, Osaka 594-1101, Japan
| | - Chiharu Kimura-Yoshida
- Department of Molecular Embryology, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840, Murodo-cho, Izumi, Osaka 594-1101, Japan
| | - Yoko Ueda
- Department of Molecular Embryology, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840, Murodo-cho, Izumi, Osaka 594-1101, Japan
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7
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Kanagawa M. Dystroglycanopathy: From Elucidation of Molecular and Pathological Mechanisms to Development of Treatment Methods. Int J Mol Sci 2021; 22:ijms222313162. [PMID: 34884967 PMCID: PMC8658603 DOI: 10.3390/ijms222313162] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 01/13/2023] Open
Abstract
Dystroglycanopathy is a collective term referring to muscular dystrophies with abnormal glycosylation of dystroglycan. At least 18 causative genes of dystroglycanopathy have been identified, and its clinical symptoms are diverse, ranging from severe congenital to adult-onset limb-girdle types. Moreover, some cases are associated with symptoms involving the central nervous system. In the 2010s, the structure of sugar chains involved in the onset of dystroglycanopathy and the functions of its causative gene products began to be identified as if they were filling the missing pieces of a jigsaw puzzle. In parallel with these discoveries, various dystroglycanopathy model mice had been created, which led to the elucidation of its pathological mechanisms. Then, treatment strategies based on the molecular basis of glycosylation began to be proposed after the latter half of the 2010s. This review briefly explains the sugar chain structure of dystroglycan and the functions of the causative gene products of dystroglycanopathy, followed by introducing the pathological mechanisms involved as revealed from analyses of dystroglycanopathy model mice. Finally, potential therapeutic approaches based on the pathological mechanisms involved are discussed.
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Affiliation(s)
- Motoi Kanagawa
- Department of Cell Biology and Molecular Medicine, Graduate School of Medicine, Ehime University, 454 Shitsukawa, Toon 791-0295, Ehime, Japan
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8
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Holman NDM, Wilkinson AJ, Smith MCM. Alanine-scanning mutagenesis of protein mannosyl-transferase from Streptomyces coelicolor reveals strong activity-stability correlation. MICROBIOLOGY-SGM 2021; 167. [PMID: 34676818 PMCID: PMC8698208 DOI: 10.1099/mic.0.001103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In Actinobacteria, protein O-mannosyl transferase (Pmt)-mediated protein O-glycosylation has an important role in cell envelope physiology. In S. coelicolor, defective Pmt leads to increased susceptibility to cell wall-targeting antibiotics, including vancomycin and β-lactams, and resistance to phage ϕC31. The aim of this study was to gain a deeper understanding of the structure and function of S. coelicolor Pmt. Sequence alignments and structural bioinformatics were used to identify target sites for an alanine-scanning mutagenesis study. Mutant alleles were introduced into pmt-deficient S. coelicolor strains using an integrative plasmid and scored for their ability to complement phage resistance and antibiotic hypersusceptibility phenotypes. Twenty-three highly conserved Pmt residues were each substituted for alanine. Six mutant alleles failed to complement the pmt▬ strains in either assay. Mapping the six corresponding residues onto a homology model of the three-dimensional structure of Pmt, indicated that five are positioned close to the predicted catalytic DE motif. Further mutagenesis to produce more conservative substitutions at these six residues produced Pmts that invariably failed to complement the DT1025 pmt▬ strain, indicating that strict residue conservation was necessary to preserve function. Cell fractionation and Western blotting of strains with the non-complementing pmt alleles revealed undetectable levels of the enzyme in either the membrane fractions or whole cell lysates. Meanwhile for all of the strains that complemented the antibiotic hypersusceptibility and phage resistance phenotypes, Pmt was readily detected in the membrane fraction. These data indicate a tight correlation between the activity of Pmt and its stability or ability to localize to the membrane.
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Affiliation(s)
| | - Anthony J Wilkinson
- Structural Biology Laboratory, York Biomedical Research Institute, Department of Chemistry, University of York, York YO10 5DD, UK
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9
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Uribe ML, Martín-Nieto J, Quereda C, Rubio-Fernández M, Cruces J, Janssen GMC, de Ru AH, van Veelen PA, Hensbergen PJ. Retinal Proteomics of a Mouse Model of Dystroglycanopathies Reveals Molecular Alterations in Photoreceptors. J Proteome Res 2021; 20:3268-3277. [PMID: 34027671 PMCID: PMC8280732 DOI: 10.1021/acs.jproteome.1c00126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Mutations in the POMT1 gene, encoding a protein O-mannosyltransferase
essential for α-dystroglycan
(α-DG) glycosylation, are frequently observed in a group of
rare congenital muscular dystrophies, collectively known as dystroglycanopathies.
However, it is hitherto unclear whether the effects seen in affected
patients can be fully ascribed to α-DG hypoglycosylation. To
study this, here we used comparative mass spectrometry-based proteomics
and immunofluorescence microscopy and investigated the changes in
the retina of mice in which Pomt1 is specifically
knocked out in photoreceptor cells. Our results demonstrate significant
proteomic changes and associated structural alteration in photoreceptor
cells of Pomt1 cKO mice. In addition to the effects
related to impaired α-DG O-mannosylation, we
observed morphological alterations in the outer segment that are associated
with dysregulation of a relatively understudied POMT1 substrate (KIAA1549),
BBSome proteins, and retinal stress markers. In conclusion, our study
provides new hypotheses to explain the phenotypic changes that are
observed in the retina of patients with dystroglycanopathies.
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Affiliation(s)
- Mary Luz Uribe
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - José Martín-Nieto
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain.,Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Cristina Quereda
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - Marcos Rubio-Fernández
- Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Universidad Autónoma de Madrid, 28029 Madrid, Spain
| | - George M C Janssen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Arnoud H de Ru
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Peter A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
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10
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Pejenaute-Ochoa MD, Santana-Molina C, Devos DP, Ibeas JI, Fernández-Álvarez A. Structural, Evolutionary, and Functional Analysis of the Protein O-Mannosyltransferase Family in Pathogenic Fungi. J Fungi (Basel) 2021; 7:jof7050328. [PMID: 33922798 PMCID: PMC8147084 DOI: 10.3390/jof7050328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/27/2022] Open
Abstract
Protein O-mannosyltransferases (Pmts) comprise a group of proteins that add mannoses to substrate proteins at the endoplasmic reticulum. This post-translational modification is important for the faithful transfer of nascent glycoproteins throughout the secretory pathway. Most fungi genomes encode three O-mannosyltransferases, usually named Pmt1, Pmt2, and Pmt4. In pathogenic fungi, Pmts, especially Pmt4, are key factors for virulence. Although the importance of Pmts for fungal pathogenesis is well established in a wide range of pathogens, questions remain regarding certain features of Pmts. For example, why does the single deletion of each pmt gene have an asymmetrical impact on host colonization? Here, we analyse the origin of Pmts in fungi and review the most important phenotypes associated with Pmt mutants in pathogenic fungi. Hence, we highlight the enormous relevance of these glycotransferases for fungal pathogenic development.
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11
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Najafi K, Mehrjoo Z, Ardalani F, Ghaderi-Sohi S, Kariminejad A, Kariminejad R, Najmabadi H. Identifying the causes of recurrent pregnancy loss in consanguineous couples using whole exome sequencing on the products of miscarriage with no chromosomal abnormalities. Sci Rep 2021; 11:6952. [PMID: 33772059 PMCID: PMC7997959 DOI: 10.1038/s41598-021-86309-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 03/08/2021] [Indexed: 12/26/2022] Open
Abstract
Recurrent miscarriages occur in about 5% of couples trying to conceive. In the past decade, the products of miscarriage have been studied using array comparative genomic hybridization (a-CGH). Within the last decade, an association has been proposed between miscarriages and single or multigenic changes, introducing the possibility of detecting other underlying genetic factors by whole exome sequencing (WES). We performed a-CGH on the products of miscarriage from 1625 Iranian women in consanguineous or non-consanguineous marriages. WES was carried out on DNA extracted from the products of miscarriage from 20 Iranian women in consanguineous marriages and with earlier normal genetic testing. Using a-CGH, a statistically significant difference was detected between the frequency of imbalances in related vs. unrelated couples (P < 0.001). WES positively identified relevant alterations in 11 genes in 65% of cases. In 45% of cases, we were able to classify these variants as pathogenic or likely pathogenic, according to the American College of Medical Genetics and Genomics guidelines, while in the remainder, the variants were classified as of unknown significance. To the best of our knowledge, our study is the first to employ WES on the products of miscarriage in consanguineous families with recurrent miscarriages regardless of the presence of fetal abnormalities. We propose that WES can be helpful in making a diagnosis of lethal disorders in consanguineous couples after prior genetic testing.
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Affiliation(s)
- Kimia Najafi
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Zohreh Mehrjoo
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
| | - Fariba Ardalani
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran
| | - Siavash Ghaderi-Sohi
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Ariana Kariminejad
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Roxana Kariminejad
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran
| | - Hossein Najmabadi
- Genetic Research Center, National Reference Laboratory for Prenatal Diagnosis, University of Social Welfare and Rehabilitation Sciences, Koodakyar Avenue, Daneshjoo Blvd, Evin, Tehran, 1985713834, Iran.
- Kariminejad-Najmabadi Pathology and Genetics Center, #2, West Side of Sanat Sq.-Metro Station, Shahrak Gharb, Tehran, 1466713713, Iran.
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12
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Ferent J, Zaidi D, Francis F. Extracellular Control of Radial Glia Proliferation and Scaffolding During Cortical Development and Pathology. Front Cell Dev Biol 2020; 8:578341. [PMID: 33178693 PMCID: PMC7596222 DOI: 10.3389/fcell.2020.578341] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/08/2020] [Indexed: 01/14/2023] Open
Abstract
During the development of the cortex, newly generated neurons migrate long-distances in the expanding tissue to reach their final positions. Pyramidal neurons are produced from dorsal progenitors, e.g., radial glia (RGs) in the ventricular zone, and then migrate along RG processes basally toward the cortex. These neurons are hence dependent upon RG extensions to support their migration from apical to basal regions. Several studies have investigated how intracellular determinants are required for RG polarity and subsequent formation and maintenance of their processes. Fewer studies have identified the influence of the extracellular environment on this architecture. This review will focus on extracellular factors which influence RG morphology and pyramidal neuronal migration during normal development and their perturbations in pathology. During cortical development, RGs are present in different strategic positions: apical RGs (aRGs) have their cell bodies located in the ventricular zone with an apical process contacting the ventricle, while they also have a basal process extending radially to reach the pial surface of the cortex. This particular conformation allows aRGs to be exposed to long range and short range signaling cues, whereas basal RGs (bRGs, also known as outer RGs, oRGs) have their cell bodies located throughout the cortical wall, limiting their access to ventricular factors. Long range signals impacting aRGs include secreted molecules present in the embryonic cerebrospinal fluid (e.g., Neuregulin, EGF, FGF, Wnt, BMP). Secreted molecules also contribute to the extracellular matrix (fibronectin, laminin, reelin). Classical short range factors include cell to cell signaling, adhesion molecules and mechano-transduction mechanisms (e.g., TAG1, Notch, cadherins, mechanical tension). Changes in one or several of these components influencing the RG extracellular environment can disrupt the development or maintenance of RG architecture on which neuronal migration relies, leading to a range of cortical malformations. First, we will detail the known long range signaling cues impacting RG. Then, we will review how short range cell contacts are also important to instruct the RG framework. Understanding how RG processes are structured by their environment to maintain and support radial migration is a critical part of the investigation of neurodevelopmental disorders.
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Affiliation(s)
- Julien Ferent
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
| | - Donia Zaidi
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
| | - Fiona Francis
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
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13
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Xu Y, Zhou H, Zhao G, Yang J, Luo Y, Sun S, Wang Z, Li S, Jin C. Genetical and O-glycoproteomic analyses reveal the roles of three protein O-mannosyltransferases in phytopathogen Fusarium oxysporum f.sp. cucumerinum. Fungal Genet Biol 2020; 134:103285. [DOI: 10.1016/j.fgb.2019.103285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/08/2019] [Accepted: 10/17/2019] [Indexed: 02/05/2023]
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14
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Francisco R, Pascoal C, Marques-da-Silva D, Morava E, Gole GA, Coman D, Jaeken J, Dos Reis Ferreira V. Keeping an eye on congenital disorders of O-glycosylation: A systematic literature review. J Inherit Metab Dis 2019; 42:29-48. [PMID: 30740740 DOI: 10.1002/jimd.12025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Congenital disorders of glycosylation (CDG) are a rapidly growing family comprising >100 genetic diseases. Some 25 CDG are pure O-glycosylation defects. Even among this CDG subgroup, phenotypic diversity is broad, ranging from mild to severe poly-organ/system dysfunction. Ophthalmic manifestations are present in 60% of these CDG. The ophthalmic manifestations in N-glycosylation-deficient patients have been described elsewhere. The present review documents the spectrum and incidence of eye disorders in patients with pure O-glycosylation defects with the aim of assisting diagnosis and management and promoting research.
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Affiliation(s)
- Rita Francisco
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Lisbon, Portugal
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
| | - Carlota Pascoal
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Lisbon, Portugal
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
| | - Dorinda Marques-da-Silva
- UCIBIO, Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Lisbon, Portugal
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
| | - Eva Morava
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
- Center for Metabolic Disease, KU Leuven, Leuven, Belgium
| | - Glen A Gole
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
- Discipline of Paediatrics and Child Health, University of Queensland, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - David Coman
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
- Department of Metabolic Medicine, The Lady Cilento Children's Hospital, Brisbane, Queensland, Australia
| | - Jaak Jaeken
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
- Center for Metabolic Disease, KU Leuven, Leuven, Belgium
| | - Vanessa Dos Reis Ferreira
- Portuguese Association for CDG, Lisbon, Portugal
- CDG & Allies - Professionals and Patient Associations International Network (CDG & Allies - PPAIN), Lisbon, Portugal
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15
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ENDO T. Mammalian O-mannosyl glycans: Biochemistry and glycopathology. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:39-51. [PMID: 30643095 PMCID: PMC6395781 DOI: 10.2183/pjab.95.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 11/05/2018] [Indexed: 05/20/2023]
Abstract
Glycosylation is an important posttranslational modification in mammals. The glycans of glycoproteins are classified into two groups, namely, N-glycans and O-glycans, according to their glycan-peptide linkage regions. Recently, O-mannosyl glycan, an O-glycan, has been shown to be important in muscle and brain development. A clear relationship between O-mannosyl glycans and the pathomechanisms of some congenital muscular dystrophies has been established in humans. Ribitol-5-phosphate is a newly identified glycan component in mammals, and its biosynthetic pathway has been elucidated. The discovery of new glycan structures and the identification of highly regulated mechanisms of glycan processing will help researchers to understand glycan functions and develop therapeutic strategies.
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Affiliation(s)
- Tamao ENDO
- Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
- Correspondence should be addressed: T. Endo, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan (e-mail: )
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16
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Nickolls AR, Bönnemann CG. The roles of dystroglycan in the nervous system: insights from animal models of muscular dystrophy. Dis Model Mech 2018; 11:11/12/dmm035931. [PMID: 30578246 PMCID: PMC6307911 DOI: 10.1242/dmm.035931] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Dystroglycan is a cell membrane protein that binds to the extracellular matrix in a variety of mammalian tissues. The α-subunit of dystroglycan (αDG) is heavily glycosylated, including a special O-mannosyl glycoepitope, relying upon this unique glycosylation to bind its matrix ligands. A distinct group of muscular dystrophies results from specific hypoglycosylation of αDG, and they are frequently associated with central nervous system involvement, ranging from profound brain malformation to intellectual disability without evident morphological defects. There is an expanding literature addressing the function of αDG in the nervous system, with recent reports demonstrating important roles in brain development and in the maintenance of neuronal synapses. Much of these data are derived from an increasingly rich array of experimental animal models. This Review aims to synthesize the information from such diverse models, formulating an up-to-date understanding about the various functions of αDG in neurons and glia of the central and peripheral nervous systems. Where possible, we integrate these data with our knowledge of the human disorders to promote translation from basic mechanistic findings to clinical therapies that take the neural phenotypes into account. Summary: Dystroglycan is a ubiquitous matrix receptor linked to brain and muscle disease. Unraveling the functions of this protein will inform basic and translational research on neural development and muscular dystrophies.
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Affiliation(s)
- Alec R Nickolls
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.,Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Carsten G Bönnemann
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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17
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Hu P, Yuan L, Deng H. Molecular genetics of the POMT1-related muscular dystrophy-dystroglycanopathies. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 778:45-50. [PMID: 30454682 DOI: 10.1016/j.mrrev.2018.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/06/2018] [Accepted: 09/10/2018] [Indexed: 01/22/2023]
Abstract
Protein O-mannosyltransferase 1 (POMT1) is a critical enzyme participating in the first step of protein O-mannosylation. Mutations in the coding gene, POMT1, have been described to be related to a series of autosomal recessive disorders associated with defective alpha-dystroglycan glycosylation, later termed muscular dystrophy-dystroglycanopathies (MDDGs). MDDGs are characterized by a broad phenotypic spectrum of congenital muscular dystrophy or later-onset limb-girdle muscular dystrophy, accompanied by variable degrees of intellectual disability, brain defects, and ocular abnormalities. To date, at least 76 disease-associated mutations in the POMT1 gene, including missense, nonsense, splicing, deletion, insertion/duplication, and insertion-deletion mutations, have been reported in the literature. In this review, we highlight the present knowledge of the identified disease-associated POMT1 gene mutations and genetic animal models related to the POMT1 gene. This review may help further normative classification of phenotypes, assist in definite clinical and genetic diagnoses, and genetic counseling, and may comprehensively improve our understanding of the basis of complex phenotypes and possible pathogenic mechanisms involved.
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Affiliation(s)
- Pengzhi Hu
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, PR China; Department of Radiology, the Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Lamei Yuan
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, PR China.
| | - Hao Deng
- Center for Experimental Medicine, the Third Xiangya Hospital, Central South University, Changsha, PR China.
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18
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Rubio-Fernández M, Uribe ML, Vicente-Tejedor J, Germain F, Susín-Lara C, Quereda C, Montoliu L, de la Villa P, Martín-Nieto J, Cruces J. Impairment of photoreceptor ribbon synapses in a novel Pomt1 conditional knockout mouse model of dystroglycanopathy. Sci Rep 2018; 8:8543. [PMID: 29867208 PMCID: PMC5986861 DOI: 10.1038/s41598-018-26855-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 05/16/2018] [Indexed: 11/09/2022] Open
Abstract
Hypoglycosylation of α-dystroglycan (α-DG) resulting from deficiency of protein O-mannosyltransferase 1 (POMT1) may cause severe neuromuscular dystrophies with brain and eye anomalies, named dystroglycanopathies. The retinal involvement of these disorders motivated us to generate a conditional knockout (cKO) mouse experiencing a Pomt1 intragenic deletion (exons 3-4) during the development of photoreceptors, mediated by the Cre recombinase expressed from the cone-rod homeobox (Crx) gene promoter. In this mouse, retinal α-DG was unglycosylated and incapable of binding laminin. Retinal POMT1 deficiency caused significant impairments in both electroretinographic recordings and optokinetic reflex in Pomt1 cKO mice, and immunohistochemical analyses revealed the absence of β-DG and of the α-DG-interacting protein, pikachurin, in the outer plexiform layer (OPL). At the ultrastructural level, noticeable alterations were observed in the ribbon synapses established between photoreceptors and bipolar cells. Therefore, O-mannosylation of α-DG in the retina carried out by POMT1 is crucial for the establishment of proper synapses at the OPL and transmission of visual information from cones and rods to their postsynaptic neurons.
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Affiliation(s)
- Marcos Rubio-Fernández
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Mary Luz Uribe
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain
| | - Javier Vicente-Tejedor
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - Francisco Germain
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - Cristina Susín-Lara
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Cristina Quereda
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain
| | - Lluis Montoliu
- Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Pedro de la Villa
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - José Martín-Nieto
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain.,Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080, Alicante, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain.
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19
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Genetics and mechanisms leading to human cortical malformations. Semin Cell Dev Biol 2018; 76:33-75. [DOI: 10.1016/j.semcdb.2017.09.031] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 02/06/2023]
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20
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Howlett R, Read N, Varghese A, Kershaw C, Hancock Y, Smith MCM. Streptomyces coelicolor strains lacking polyprenol phosphate mannose synthase and protein O-mannosyl transferase are hyper-susceptible to multiple antibiotics. MICROBIOLOGY-SGM 2018; 164:369-382. [PMID: 29458553 PMCID: PMC5882110 DOI: 10.1099/mic.0.000605] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Polyprenol phosphate mannose (PPM) is a lipid-linked sugar donor used by extra-cytoplasmic glycosyl tranferases in bacteria. PPM is synthesized by polyprenol phosphate mannose synthase, Ppm1, and in most Actinobacteria is used as the sugar donor for protein O-mannosyl transferase, Pmt, in protein glycosylation. Ppm1 and Pmt have homologues in yeasts and humans, where they are required for protein O-mannosylation. Actinobacteria also use PPM for lipoglycan biosynthesis. Here we show that ppm1 mutants of Streptomyces coelicolor have increased susceptibility to a number of antibiotics that target cell wall biosynthesis. The pmt mutants also have mildly increased antibiotic susceptibilities, in particular to β-lactams and vancomycin. Despite normal induction of the vancomycin gene cluster, vanSRJKHAX, the pmt and ppm1 mutants remained highly vancomycin sensitive indicating that the mechanism of resistance is blocked post-transcriptionally. Differential RNA expression analysis indicated that catabolic pathways were downregulated and anabolic ones upregulated in the ppm1 mutant compared to the parent or complemented strains. Of note was the increase in expression of fatty acid biosynthetic genes in the ppm1- mutant. A change in lipid composition was confirmed using Raman spectroscopy, which showed that the ppm1- mutant had a greater relative proportion of unsaturated fatty acids compared to the parent or the complemented mutant. Taken together, these data suggest that an inability to synthesize PPM (ppm1) and loss of the glycoproteome (pmt- mutant) can detrimentally affect membrane or cell envelope functions leading to loss of intrinsic and, in the case of vancomycin, acquired antibiotic resistance.
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Affiliation(s)
| | | | - Anpu Varghese
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | | | - Y Hancock
- Department of Physics, University of York, York, UK.,York Centre for Complex Systems Analysis, University of York, York, UK
| | - Margaret C M Smith
- Department of Biology, University of York, York, UK.,Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
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21
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Protein O-Mannosyltransferases Affect Sensory Axon Wiring and Dynamic Chirality of Body Posture in the Drosophila Embryo. J Neurosci 2017; 38:1850-1865. [PMID: 29167399 DOI: 10.1523/jneurosci.0346-17.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 02/06/2023] Open
Abstract
Genetic defects in protein O-mannosyltransferase 1 (POMT1) and POMT2 underlie severe muscular dystrophies. POMT genes are evolutionarily conserved in metazoan organisms. In Drosophila, both male and female POMT mutants show a clockwise rotation of adult abdominal segments, suggesting a chirality of underlying pathogenic mechanisms. Here we described and analyzed a similar phenotype in POMT mutant embryos that shows left-handed body torsion. Our experiments demonstrated that coordinated muscle contraction waves are associated with asymmetric embryo rolling, unveiling a new chirality marker in Drosophila development. Using genetic and live-imaging approaches, we revealed that the torsion phenotype results from differential rolling and aberrant patterning of peristaltic waves of muscle contractions. Our results demonstrated that peripheral sensory neurons are required for normal contractions that prevent the accumulation of torsion. We found that POMT mutants show abnormal axonal connections of sensory neurons. POMT transgenic expression limited to sensory neurons significantly rescued the torsion phenotype, axonal connectivity defects, and abnormal contractions in POMT mutant embryos. Together, our data suggested that protein O-mannosylation is required for normal sensory feedback to control coordinated muscle contractions and body posture. This mechanism may shed light on analogous functions of POMT genes in mammals and help to elucidate the etiology of neurological defects in muscular dystrophies.SIGNIFICANCE STATEMENT Protein O-mannosyltransferases (POMTs) are evolutionarily conserved in metazoans. Mutations in POMTs cause severe muscular dystrophies associated with pronounced neurological defects. However, neurological functions of POMTs remain poorly understood. We demonstrated that POMT mutations in Drosophila result in abnormal muscle contractions and cause embryo torsion. Our experiments uncovered a chirality of embryo movements and a unique POMT-dependent mechanism that maintains symmetry of a developing system affected by chiral forces. Furthermore, POMTs were found to be required for proper axon connectivity of sensory neurons, suggesting that O-mannosylation regulates the sensory feedback controlling muscle contractions. This novel POMT function in the peripheral nervous system may shed light on analogous functions in mammals and help to elucidate pathomechanisms of neurological abnormalities in muscular dystrophies.
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22
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Protein O-Mannosylation in the Murine Brain: Occurrence of Mono-O-Mannosyl Glycans and Identification of New Substrates. PLoS One 2016; 11:e0166119. [PMID: 27812179 PMCID: PMC5094735 DOI: 10.1371/journal.pone.0166119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 10/24/2016] [Indexed: 12/25/2022] Open
Abstract
Protein O-mannosylation is a post-translational modification essential for correct development of mammals. In humans, deficient O-mannosylation results in severe congenital muscular dystrophies often associated with impaired brain and eye development. Although various O-mannosylated proteins have been identified in the recent years, the distribution of O-mannosyl glycans in the mammalian brain and target proteins are still not well defined. In the present study, rabbit monoclonal antibodies directed against the O-mannosylated peptide YAT(α1-Man)AV were generated. Detailed characterization of clone RKU-1-3-5 revealed that this monoclonal antibody recognizes O-linked mannose also in different peptide and protein contexts. Using this tool, we observed that mono-O-mannosyl glycans occur ubiquitously throughout the murine brain but are especially enriched at inhibitory GABAergic neurons and at the perineural nets. Using a mass spectrometry-based approach, we further identified glycoproteins from the murine brain that bear single O-mannose residues. Among the candidates identified are members of the cadherin and plexin superfamilies and the perineural net protein neurocan. In addition, we identified neurexin 3, a cell adhesion protein involved in synaptic plasticity, and inter-alpha-trypsin inhibitor 5, a protease inhibitor important in stabilizing the extracellular matrix, as new O-mannosylated glycoproteins.
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23
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Servián-Morilla E, Takeuchi H, Lee TV, Clarimon J, Mavillard F, Area-Gómez E, Rivas E, Nieto-González JL, Rivero MC, Cabrera-Serrano M, Gómez-Sánchez L, Martínez-López JA, Estrada B, Márquez C, Morgado Y, Suárez-Calvet X, Pita G, Bigot A, Gallardo E, Fernández-Chacón R, Hirano M, Haltiwanger RS, Jafar-Nejad H, Paradas C. A POGLUT1 mutation causes a muscular dystrophy with reduced Notch signaling and satellite cell loss. EMBO Mol Med 2016; 8:1289-1309. [PMID: 27807076 PMCID: PMC5090660 DOI: 10.15252/emmm.201505815] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Skeletal muscle regeneration by muscle satellite cells is a physiological mechanism activated upon muscle damage and regulated by Notch signaling. In a family with autosomal recessive limb‐girdle muscular dystrophy, we identified a missense mutation in POGLUT1 (protein O‐glucosyltransferase 1), an enzyme involved in Notch posttranslational modification and function. In vitro and in vivo experiments demonstrated that the mutation reduces O‐glucosyltransferase activity on Notch and impairs muscle development. Muscles from patients revealed decreased Notch signaling, dramatic reduction in satellite cell pool and a muscle‐specific α‐dystroglycan hypoglycosylation not present in patients' fibroblasts. Primary myoblasts from patients showed slow proliferation, facilitated differentiation, and a decreased pool of quiescent PAX7+ cells. A robust rescue of the myogenesis was demonstrated by increasing Notch signaling. None of these alterations were found in muscles from secondary dystroglycanopathy patients. These data suggest that a key pathomechanism for this novel form of muscular dystrophy is Notch‐dependent loss of satellite cells.
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Affiliation(s)
- Emilia Servián-Morilla
- Neuromuscular Disorders Unit, Department of Neurology, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Hideyuki Takeuchi
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Tom V Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Jordi Clarimon
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Memory Unit, Department of Neurology and Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Fabiola Mavillard
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Estela Area-Gómez
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Eloy Rivas
- Department of Pathology, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Jose L Nieto-González
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Maria C Rivero
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Macarena Cabrera-Serrano
- Neuromuscular Disorders Unit, Department of Neurology, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Leonardo Gómez-Sánchez
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Jose A Martínez-López
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Beatriz Estrada
- Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo Olavide, Sevilla, Spain
| | - Celedonio Márquez
- Neuromuscular Disorders Unit, Department of Neurology, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | | | - Xavier Suárez-Calvet
- Laboratori de Malalties Neuromusculars, Institut de Recerca de HSCSP, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Guillermo Pita
- Human Genotyping Unit-CeGen, Spanish National Cancer Research Centre, Madrid, Spain
| | - Anne Bigot
- UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Sorbonne Universités, Paris, France
| | - Eduard Gallardo
- Laboratori de Malalties Neuromusculars, Institut de Recerca de HSCSP, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Rafael Fernández-Chacón
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Medical Physiology and Biophysics, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Robert S Haltiwanger
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Hamed Jafar-Nejad
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Carmen Paradas
- Neuromuscular Disorders Unit, Department of Neurology, Instituto de Biomedicina de Sevilla, Hospital U. Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Neurology, Columbia University Medical Center, New York, NY, USA
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24
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Izquierdo-Lahuerta A, de Luis O, Gómez-Esquer F, Cruces J, Coloma A. Gallus gallus orthologous to human alpha-dystroglycanopathies candidate genes: Gene expression and characterization during chicken embryogenesis. Biochem Biophys Res Commun 2016; 478:1043-8. [PMID: 27553274 DOI: 10.1016/j.bbrc.2016.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/04/2016] [Indexed: 10/21/2022]
Abstract
Alpha-dystroglycanopathies are a heterogenic group of human rare diseases that have in common defects of α-dystroglycan O-glycosylation. These congenital disorders share common features as muscular dystrophy, malformations on central nervous system and more rarely altered ocular development, as well as mutations on a set of candidate genes involved on those syndromes. Severity of the syndromes is variable, appearing Walker-Warburg as the most severe where mutations at protein O-mannosyl transferases POMT1 and POMT2 genes are frequently described. When studying the lack of MmPomt1 in mouse embryonic development, as a murine model of Walker-Warburg syndrome, MmPomt1 null phenotype was lethal because Reitchert's membrane fails during embryonic development. Here, we report gene expression from Gallus gallus orthologous genes to human candidates on alpha-dystroglycanopathies POMT1, POMT2, POMGnT1, FKTN, FKRP and LARGE, making special emphasis in expression and localization of GgPomt1. Results obtained by quantitative RT-PCR, western-blot and immunochemistry revealed close gene expression patterns among human and chicken at key tissues affected during development when suffering an alpha-dystroglycanopathy, leading us to stand chicken as a useful animal model for molecular characterization of glycosyltransferases involved in the O-glycosylation of α-Dystroglycan and its role in embryonic development.
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Affiliation(s)
- Adriana Izquierdo-Lahuerta
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica, y Biología Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avda. de Atenas s/n. 28922, Alcorcón, Madrid, Spain.
| | - Oscar de Luis
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica, y Biología Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avda. de Atenas s/n. 28922, Alcorcón, Madrid, Spain
| | - Francisco Gómez-Esquer
- Departamento de Ciencias Básicas de la Salud, Area de Anatomía Humana y Embriología, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avda. de Atenas s/n, 28922, Alcorcón, Madrid, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029, Madrid, Spain
| | - Antonio Coloma
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica, y Biología Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avda. de Atenas s/n. 28922, Alcorcón, Madrid, Spain
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25
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Protein O-mannosylation in the early secretory pathway. Curr Opin Cell Biol 2016; 41:100-8. [DOI: 10.1016/j.ceb.2016.04.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/19/2016] [Accepted: 04/25/2016] [Indexed: 12/30/2022]
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26
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Bausewein D, Engel J, Jank T, Schoedl M, Strahl S. Functional Similarities between the Protein O-Mannosyltransferases Pmt4 from Bakers' Yeast and Human POMT1. J Biol Chem 2016; 291:18006-15. [PMID: 27358400 PMCID: PMC5016187 DOI: 10.1074/jbc.m116.739128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 11/21/2022] Open
Abstract
Protein O-mannosylation is an essential post-translational modification. It is initiated in the endoplasmic reticulum by a family of protein O-mannosyltransferases that are conserved from yeast (PMTs) to human (POMTs). The degree of functional conservation between yeast and human protein O-mannosyltransferases is uncharacterized. In bakers' yeast, the main in vivo activities are due to heteromeric Pmt1-Pmt2 and homomeric Pmt4 complexes. Here we describe an enzymatic assay that allowed us to monitor Pmt4 activity in vitro. We demonstrate that detergent requirements and acceptor substrates of yeast Pmt4 are different from Pmt1-Pmt2, but resemble that of human POMTs. Furthermore, we mimicked two POMT1 amino acid exchanges (G76R and V428D) that result in severe congenital muscular dystrophies in humans, in yeast Pmt4 (I112R and I435D). In vivo and in vitro analyses showed that general features such as protein stability of the Pmt4 variants were not significantly affected, however, the mutants proved largely enzymatically inactive. Our results demonstrate functional and biochemical similarities between POMT1 and its orthologue from bakers' yeast Pmt4.
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Affiliation(s)
- Daniela Bausewein
- From the Centre for Organismal Studies, Cell Chemistry, Heidelberg University, 69120 Heidelberg, Germany
| | - Jakob Engel
- From the Centre for Organismal Studies, Cell Chemistry, Heidelberg University, 69120 Heidelberg, Germany
| | - Thomas Jank
- From the Centre for Organismal Studies, Cell Chemistry, Heidelberg University, 69120 Heidelberg, Germany
| | - Maria Schoedl
- From the Centre for Organismal Studies, Cell Chemistry, Heidelberg University, 69120 Heidelberg, Germany
| | - Sabine Strahl
- From the Centre for Organismal Studies, Cell Chemistry, Heidelberg University, 69120 Heidelberg, Germany
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27
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Analysis of phenotype, enzyme activity and genotype of Chinese patients with POMT1 mutation. J Hum Genet 2016; 61:753-9. [PMID: 27193224 DOI: 10.1038/jhg.2016.42] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 03/04/2016] [Accepted: 03/30/2016] [Indexed: 01/20/2023]
Abstract
Protein O-mannosyltransferase 1 (POMT1) is a glycosyltransferase involved in α-dystroglycan glycosylation. POMT1 mutations cause a wide spectrum of clinical conditions from Walker-Warburg syndrome (WWS), which involves muscle, eye and brain abnormalities, to mild forms of limb-girdle muscular dystrophy with mental retardation. We aimed to elucidate the impact of different POMT1 mutations on the clinical phenotype. We report five Chinese patients with POMT1 mutations: one had a typical clinical manifestation of WWS, and the other four were diagnosed with congenital muscular dystrophy with mental retardation of varying severity. We analyzed the influence of the POMT1 mutations on POMT activity by assaying the patients' muscles and cultured skin fibroblasts. We demonstrated different levels of decreased POMT activity that correlated highly with decreased α-dystroglycan glycosylation. Our results suggest that POMT activity is inversely proportional to clinical severity, and demonstrate that skin fibroblasts can be used for differential diagnosis of patients with α-dystroglycanopathies. We have provided clinical, histological, enzymatic and genetic evidence of POMT1 involvement in five unrelated Chinese patients.
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28
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Stanley P. What Have We Learned from Glycosyltransferase Knockouts in Mice? J Mol Biol 2016; 428:3166-3182. [PMID: 27040397 DOI: 10.1016/j.jmb.2016.03.025] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 11/16/2022]
Abstract
There are five major classes of glycan including N- and O-glycans, glycosaminoglycans, glycosphingolipids, and glycophosphatidylinositol anchors, all expressed at the molecular frontier of each mammalian cell. Numerous biological consequences of altering the expression of mammalian glycans are understood at a mechanistic level, but many more remain to be characterized. Mouse mutants with deleted, defective, or misexpressed genes that encode activities necessary for glycosylation have led the way to identifying key functions of glycans in biology. However, with the advent of exome sequencing, humans with mutations in genes involved in glycosylation are also revealing specific requirements for glycans in mammalian development. The aim of this review is to summarize glycosylation genes that are necessary for mouse embryonic development, pathway-specific glycosylation genes whose deletion leads to postnatal morbidity, and glycosylation genes for which effects are mild, but perturbation of the organism may reveal functional consequences. General strategies for generating and interpreting the phenotype of mice with glycosylation defects are discussed in relation to human congenital disorders of glycosylation (CDG).
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Affiliation(s)
- Pamela Stanley
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA.
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29
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Xu M, Yamada T, Sun Z, Eblimit A, Lopez I, Wang F, Manya H, Xu S, Zhao L, Li Y, Kimchi A, Sharon D, Sui R, Endo T, Koenekoop RK, Chen R. Mutations in POMGNT1 cause non-syndromic retinitis pigmentosa. Hum Mol Genet 2016; 25:1479-88. [PMID: 26908613 DOI: 10.1093/hmg/ddw022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/25/2016] [Indexed: 11/12/2022] Open
Abstract
A growing number of human diseases have been linked to defects in protein glycosylation that affects a wide range of organs. Among them, O-mannosylation is an unusual type of protein glycosylation that is largely restricted to the muscular and nerve system. Consistently, mutations in genes involved in the O-mannosylation pathway result in infantile-onset, severe developmental defects involving skeleton muscle, brain and eye, such as the muscle-eye-brain disease (MIM no. 253280). However, the functional importance of O-mannosylation in these tissues at later stages remains largely unknown. In our study, we have identified recessive mutations in POMGNT1, which encodes an essential component in O-mannosylation pathway, in three unrelated families with autosomal recessive retinitis pigmentosa (RP), but without extraocular involvement. Enzymatic assay of these mutant alleles demonstrate that they greatly reduce the POMGNT1 enzymatic activity and are likely to be hypomorphic. Immunohistochemistry shows that POMGNT1 is specifically expressed in photoreceptor basal body. Taken together, our work identifies a novel disease-causing gene for RP and indicates that proper protein O-mannosylation is not only essential for early organ development, but also important for maintaining survival and function of the highly specialized retinal cells at later stages.
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Affiliation(s)
- Mingchu Xu
- Department of Molecular and Human Genetics, Human Genome Sequencing Center
| | - Takeyuki Yamada
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan
| | - Zixi Sun
- Department of Ophthalmology, Peking Union Medical College, Beijing 100730, China
| | - Aiden Eblimit
- Department of Molecular and Human Genetics, Human Genome Sequencing Center
| | - Irma Lopez
- McGill Ocular Genetics Laboratory, McGill University Health Centre, Montreal, Quebec H3H 1P3, Canada and
| | - Feng Wang
- Department of Molecular and Human Genetics, Human Genome Sequencing Center
| | - Hiroshi Manya
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan
| | - Shan Xu
- Department of Molecular and Human Genetics, Human Genome Sequencing Center
| | - Li Zhao
- Department of Molecular and Human Genetics, Human Genome Sequencing Center, Structural and Computational Biology and Molecular Biophysics Graduate Program
| | - Yumei Li
- Department of Molecular and Human Genetics, Human Genome Sequencing Center
| | - Adva Kimchi
- Departments of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Dror Sharon
- Departments of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College, Beijing 100730, China
| | - Tamao Endo
- Molecular Glycobiology, Research Team for Mechanism of Aging, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan
| | - Robert K Koenekoop
- McGill Ocular Genetics Laboratory, McGill University Health Centre, Montreal, Quebec H3H 1P3, Canada and
| | - Rui Chen
- Department of Molecular and Human Genetics, Human Genome Sequencing Center, Structural and Computational Biology and Molecular Biophysics Graduate Program, The Verna and Marrs Mclean Department of Biochemistry and Molecular Biology and Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA,
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30
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Neubert P, Halim A, Zauser M, Essig A, Joshi HJ, Zatorska E, Larsen ISB, Loibl M, Castells-Ballester J, Aebi M, Clausen H, Strahl S. Mapping the O-Mannose Glycoproteome in Saccharomyces cerevisiae. Mol Cell Proteomics 2016; 15:1323-37. [PMID: 26764011 PMCID: PMC4824858 DOI: 10.1074/mcp.m115.057505] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Indexed: 11/17/2022] Open
Abstract
O-Mannosylation is a vital protein modification conserved from fungi to humans. Yeast is a perfect model to study this post-translational modification, because in contrast to mammals O-mannosylation is the only type of O-glycosylation. In an essential step toward the full understanding of protein O-mannosylation we mapped the O-mannose glycoproteome in baker's yeast. Taking advantage of an O-glycan elongation deficient yeast strain to simplify sample complexity, we identified over 500 O-glycoproteins from all subcellular compartments for which over 2300 O-mannosylation sites were mapped by electron-transfer dissociation (ETD)-based MS/MS. In this study, we focus on the 293 O-glycoproteins (over 1900 glycosylation sites identified by ETD-MS/MS) that enter the secretory pathway and are targets of ER-localized protein O-mannosyltransferases. We find that O-mannosylation is not only a prominent modification of cell wall and plasma membrane proteins, but also of a large number of proteins from the secretory pathway with crucial functions in protein glycosylation, folding, quality control, and trafficking. The analysis of glycosylation sites revealed that O-mannosylation is favored in unstructured regions and β-strands. Furthermore, O-mannosylation is impeded in the proximity of N-glycosylation sites suggesting the interplay of these types of post-translational modifications. The detailed knowledge of the target proteins and their O-mannosylation sites opens for discovery of new roles of this essential modification in eukaryotes, and for a first glance on the evolution of different types of O-glycosylation from yeast to mammals.
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Affiliation(s)
- Patrick Neubert
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Adnan Halim
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Martin Zauser
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Andreas Essig
- ¶Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Hiren J Joshi
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Ewa Zatorska
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Ida Signe Bohse Larsen
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Martin Loibl
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Joan Castells-Ballester
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
| | - Markus Aebi
- ¶Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Henrik Clausen
- §Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Sabine Strahl
- From the ‡Centre for Organismal Studies (COS), Department of Cell Chemistry, Heidelberg University, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany;
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31
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Where do we stand in trial readiness for autosomal recessive limb girdle muscular dystrophies? Neuromuscul Disord 2015; 26:111-25. [PMID: 26810373 DOI: 10.1016/j.nmd.2015.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/27/2015] [Accepted: 11/29/2015] [Indexed: 12/20/2022]
Abstract
Autosomal recessive limb girdle muscular dystrophies (LGMD2) are a group of genetically heterogeneous diseases that are typically characterised by progressive weakness and wasting of the shoulder and pelvic girdle muscles. Many of the more than 20 different conditions show overlapping clinical features with other forms of muscular dystrophy, congenital, myofibrillar or even distal myopathies and also with acquired muscle diseases. Although individually extremely rare, all types of LGMD2 together form an important differential diagnostic group among neuromuscular diseases. Despite improved diagnostics and pathomechanistic insight, a curative therapy is currently lacking for any of these diseases. Medical care consists of the symptomatic treatment of complications, aiming to improve life expectancy and quality of life. Besides well characterised pre-clinical tools like animal models and cell culture assays, the determinants of successful drug development programmes for rare diseases include a good understanding of the phenotype and natural history of the disease, the existence of clinically relevant outcome measures, guidance on care standards, up to date patient registries, and, ideally, biomarkers that can help assess disease severity or drug response. Strong patient organisations driving research and successful partnerships between academia, advocacy, industry and regulatory authorities can also help accelerate the elaboration of clinical trials. All these determinants constitute aspects of translational research efforts and influence patient access to therapies. Here we review the current status of determinants of successful drug development programmes for LGMD2, and the challenges of translating promising therapeutic strategies into effective and accessible treatments for patients.
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32
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Ramkumar N, Harvey BM, Lee JD, Alcorn HL, Silva-Gagliardi NF, McGlade CJ, Bestor TH, Wijnholds J, Haltiwanger RS, Anderson KV. Protein O-Glucosyltransferase 1 (POGLUT1) Promotes Mouse Gastrulation through Modification of the Apical Polarity Protein CRUMBS2. PLoS Genet 2015; 11:e1005551. [PMID: 26496195 PMCID: PMC4619674 DOI: 10.1371/journal.pgen.1005551] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/02/2015] [Indexed: 01/02/2023] Open
Abstract
Crumbs family proteins are apical transmembrane proteins with ancient roles in cell polarity. Mouse Crumbs2 mutants arrest at midgestation with abnormal neural plate morphology and a deficit of mesoderm caused by defects in gastrulation. We identified an ENU-induced mutation, wsnp, that phenocopies the Crumbs2 null phenotype. We show that wsnp is a null allele of Protein O-glucosyltransferase 1 (Poglut1), which encodes an enzyme previously shown to add O-glucose to EGF repeats in the extracellular domain of Drosophila and mammalian Notch, but the role of POGLUT1 in mammalian gastrulation has not been investigated. As predicted, we find that POGLUT1 is essential for Notch signaling in the early mouse embryo. However, the loss of mouse POGLUT1 causes an earlier and more dramatic phenotype than does the loss of activity of the Notch pathway, indicating that POGLUT1 has additional biologically relevant substrates. Using mass spectrometry, we show that POGLUT1 modifies EGF repeats in the extracellular domain of full-length mouse CRUMBS2. CRUMBS2 that lacks the O-glucose modification fails to be enriched on the apical plasma membrane and instead accumulates in the endoplasmic reticulum. The data demonstrate that CRUMBS2 is the target of POGLUT1 for the gastrulation epithelial-to-mesenchymal transitions (EMT) and that all activity of CRUMBS2 depends on modification by POGLUT1. Mutations in human POGLUT1 cause Dowling-Degos Disease, POGLUT1 is overexpressed in a variety of tumor cells, and mutations in the EGF repeats of human CRUMBS proteins are associated with human congenital nephrosis, retinitis pigmentosa and retinal degeneration, suggesting that O-glucosylation of CRUMBS proteins has broad roles in human health.
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Affiliation(s)
- Nitya Ramkumar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America
| | - Beth M. Harvey
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Jeffrey D. Lee
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Heather L. Alcorn
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Nancy F. Silva-Gagliardi
- The Hospital for Sick Children, Arthur and Sonia Labatt Brain Tumor Research Center and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - C. Jane McGlade
- The Hospital for Sick Children, Arthur and Sonia Labatt Brain Tumor Research Center and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Timothy H. Bestor
- Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, New York, United States of America
| | - Jan Wijnholds
- Department of Neuromedical Genetics, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Robert S. Haltiwanger
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Kathryn V. Anderson
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
- * E-mail:
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Ryckebüsch L. [Potential of the zebrafish model to study congenital muscular dystrophies]. Med Sci (Paris) 2015; 31:912-9. [PMID: 26481031 DOI: 10.1051/medsci/20153110018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In order to better understand the complexity of congenital muscular dystrophies (CMD) and develop new strategies to cure them, it is important to establish new disease models. Due to its numerous helpful attributes, the zebrafish has recently become a very powerful animal model for the study of CMD. For some CMD, this vertebrate model is phenotypically closer to human pathology than the murine model. Over the last few years, researchers have developed innovative techniques to screen rapidly and on a large scale for muscle defects in zebrafish. Furthermore, new genome editing techniques in zebrafish make possible the identification of new disease models. In this review, the major attributes of zebrafish for CMD studies are discussed and the principal models of CMD in zebrafish are highlighted.
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Affiliation(s)
- Lucile Ryckebüsch
- Division of biological sciences, university of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, La Jolla, États-Unis
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Stouffer MA, Golden JA, Francis F. Neuronal migration disorders: Focus on the cytoskeleton and epilepsy. Neurobiol Dis 2015; 92:18-45. [PMID: 26299390 DOI: 10.1016/j.nbd.2015.08.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 08/05/2015] [Accepted: 08/12/2015] [Indexed: 01/28/2023] Open
Abstract
A wide spectrum of focal, regional, or diffuse structural brain abnormalities, collectively known as malformations of cortical development (MCDs), frequently manifest with intellectual disability (ID), epilepsy, and/or autistic spectrum disorder (ASD). As the acronym suggests, MCDs are perturbations of the normal architecture of the cerebral cortex and hippocampus. The pathogenesis of these disorders remains incompletely understood; however, one area that has provided important insights has been the study of neuronal migration. The amalgamation of human genetics and experimental studies in animal models has led to the recognition that common genetic causes of neurodevelopmental disorders, including many severe epilepsy syndromes, are due to mutations in genes regulating the migration of newly born post-mitotic neurons. Neuronal migration genes often, though not exclusively, code for proteins involved in the function of the cytoskeleton. Other cellular processes, such as cell division and axon/dendrite formation, which similarly depend on cytoskeletal functions, may also be affected. We focus here on how the susceptibility of the highly organized neocortex and hippocampus may be due to their laminar organization, which involves the tight regulation, both temporally and spatially, of gene expression, specialized progenitor cells, the migration of neurons over large distances and a birthdate-specific layering of neurons. Perturbations in neuronal migration result in abnormal lamination, neuronal differentiation defects, abnormal cellular morphology and circuit formation. Ultimately this results in disorganized excitatory and inhibitory activity leading to the symptoms observed in individuals with these disorders.
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Affiliation(s)
- Melissa A Stouffer
- INSERM UMRS 839, Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Jeffrey A Golden
- Department of Pathology, Brigham & Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
| | - Fiona Francis
- INSERM UMRS 839, Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Paris, France; Institut du Fer à Moulin, Paris, France.
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Kim H, Thak EJ, Lee DJ, Agaphonov MO, Kang HA. Hansenula polymorpha Pmt4p Plays Critical Roles in O-Mannosylation of Surface Membrane Proteins and Participates in Heteromeric Complex Formation. PLoS One 2015; 10:e0129914. [PMID: 26134523 PMCID: PMC4489896 DOI: 10.1371/journal.pone.0129914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/14/2015] [Indexed: 01/09/2023] Open
Abstract
O-mannosylation, the addition of mannose to serine and threonine residues of secretory proteins, is a highly conserved post-translational modification found in organisms ranging from bacteria to humans. Here, we report the functional and molecular characterization of the HpPMT4 gene encoding a protein O-mannosyltransferase in the thermotolerant methylotrophic yeast Hansenula polymorpha, an emerging host for the production of therapeutic recombinant proteins. Compared to the deletion of HpPMT1, deletion of another major PMT gene, HpPMT4, resulted in more increased sensitivity to the antibiotic hygromycin B, caffeine, and osmotic stresses, but did not affect the thermotolerance of H. polymorpha. Notably, the deletion of HpPMT4 generated severe defects in glycosylation of the surface sensor proteins HpWsc1p and HpMid2p, with marginal effects on secreted glycoproteins such as chitinase and HpYps1p lacking a GPI anchor. However, despite the severely impaired mannosylation of surface sensor proteins in the Hppmt4∆ mutant, the phosphorylation of HpMpk1p and HpHog1p still showed a high increase upon treatment with cell wall disturbing agents or high concentrations of salts. The conditional Hppmt1pmt4∆ double mutant strains displayed severely impaired growth, enlarged cell size, and aberrant cell separation, implying that the loss of HpPMT4 function might be lethal to cells in the absence of HpPmt1p. Moreover, the HpPmt4 protein was found to form not only a homomeric complex but also a heteromeric complex with either HpPmt1p or HpPmt2p. Altogether, our results support the function of HpPmt4p as a key player in O-mannosylation of cell surface proteins and its participation in the formation of heterodimers with other PMT members, besides homodimer formation, in H. polymorpha.
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Affiliation(s)
- Hyunah Kim
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Eun Jung Thak
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Dong-Jik Lee
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Michael O. Agaphonov
- A.N. Bach Institute of Biochemistry of the Russian Academy of Sciences, Moscow, Russia
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
- * E-mail:
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Xu C, Ng DT. O-mannosylation: The other glycan player of ER quality control. Semin Cell Dev Biol 2015; 41:129-34. [DOI: 10.1016/j.semcdb.2015.01.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 01/30/2015] [Indexed: 01/07/2023]
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Whitmore C, Morgan J. What do mouse models of muscular dystrophy tell us about the DAPC and its components? Int J Exp Pathol 2014; 95:365-77. [PMID: 25270874 PMCID: PMC4285463 DOI: 10.1111/iep.12095] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/16/2014] [Indexed: 12/17/2022] Open
Abstract
There are over 30 mouse models with mutations or inactivations in the dystrophin-associated protein complex. This complex is thought to play a crucial role in the functioning of muscle, as both a shock absorber and signalling centre, although its role in the pathogenesis of muscular dystrophy is not fully understood. The first mouse model of muscular dystrophy to be identified with a mutation in a component of the dystrophin-associated complex (dystrophin) was the mdx mouse in 1984. Here, we evaluate the key characteristics of the mdx in comparison with other mouse mutants with inactivations in DAPC components, along with key modifiers of the disease phenotype. By discussing the differences between the individual phenotypes, we show that the functioning of the DAPC and consequently its role in the pathogenesis is more complicated than perhaps currently appreciated.
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Affiliation(s)
- Charlotte Whitmore
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, Institute of Child Health, University College LondonLondon, UK
| | - Jennifer Morgan
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, Institute of Child Health, University College LondonLondon, UK
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Willer T, Inamori KI, Venzke D, Harvey C, Morgensen G, Hara Y, Beltrán Valero de Bernabé D, Yu L, Wright KM, Campbell KP. The glucuronyltransferase B4GAT1 is required for initiation of LARGE-mediated α-dystroglycan functional glycosylation. eLife 2014; 3. [PMID: 25279699 PMCID: PMC4227050 DOI: 10.7554/elife.03941] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/01/2014] [Indexed: 12/13/2022] Open
Abstract
Dystroglycan is a cell membrane receptor that organizes the basement membrane by binding ligands in the extracellular matrix. Proper glycosylation of the α-dystroglycan (α-DG) subunit is essential for these activities, and lack thereof results in neuromuscular disease. Currently, neither the glycan synthesis pathway nor the roles of many known or putative glycosyltransferases that are essential for this process are well understood. Here we show that FKRP, FKTN, TMEM5 and B4GAT1 (formerly known as B3GNT1) localize to the Golgi and contribute to the O-mannosyl post-phosphorylation modification of α-DG. Moreover, we assigned B4GAT1 a function as a xylose β1,4-glucuronyltransferase. Nuclear magnetic resonance studies confirmed that a glucuronic acid β1,4-xylose disaccharide synthesized by B4GAT1 acts as an acceptor primer that can be elongated by LARGE with the ligand-binding heteropolysaccharide. Our findings greatly broaden the understanding of α-DG glycosylation and provide mechanistic insight into why mutations in B4GAT1 disrupt dystroglycan function and cause disease. DOI:http://dx.doi.org/10.7554/eLife.03941.001 Dystroglycan is a protein that is critical for the proper function of many tissues, especially muscles and brain. Dystroglycan helps to connect the structural network inside the cell with the matrix outside of the cell. The extracellular matrix fills the space between the cells to serve as a scaffold and hold cells together within a tissue. It is well established that the interaction of cells with their extracellular environments is important for structuring tissues, as well as for helping cells to specialize and migrate. These interactions also play a role in the progression of cancer. As is the case for many proteins, dystroglycan must be modified with particular sugar molecules in order to work correctly. Enzymes called glycosyltransferases are responsible for sequentially assembling a complex array of sugar molecules on dystroglycan. This modification is essential for making dystroglycan ‘sticky’, so it can bind to the components of the extracellular matrix. If sugar molecules are added incorrectly, dystroglycan loses its ability to bind to these components. This causes congenital muscular dystrophies, a group of diseases that are characterized by a progressive loss of muscle function. Willer et al. use a wide range of experimental techniques to investigate the types of sugar molecules added to dystroglycan, the overall structure of the resulting ‘sticky’ complex and the mechanism whereby it is built. This reveals that a glycosyltransferase known as B3GNT1 is one of the enzymes responsible for adding a sugar molecule to the complex. This enzyme was first described in the literature over a decade ago, and the name B3GNT1 was assigned, according to a code, to reflect the sugar molecule it was thought to transfer to proteins. However, Willer et al. (and independently, Praissman et al.) find that this enzyme actually attaches a different sugar modification to dystroglycan, and so should therefore be called B4GAT1 instead. Willer et al. find that the sugar molecule added by the B4GAT1 enzyme acts as a platform for the assembly of a much larger sugar polymer that cells use to anchor themselves within a tissue. Some viruses–including Lassa virus, which causes severe fever and bleeding–also use the ‘sticky’ sugar modification of dystroglycan to bind to and invade cells, causing disease in humans. Understanding the structure of this complex, and how these sugar modifications are added to dystroglycan, could therefore help to develop treatments for a wide range of diseases like progressive muscle weakening and viral infections. DOI:http://dx.doi.org/10.7554/eLife.03941.002
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Affiliation(s)
- Tobias Willer
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Kei-Ichiro Inamori
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - David Venzke
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Corinne Harvey
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Greg Morgensen
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Yuji Hara
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
| | | | - Liping Yu
- Medical Nuclear Magnetic Resonance Facility, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Kevin M Wright
- Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Kevin P Campbell
- Department of Molecular Physiology and Biophysics, University of Iowa, Carver College of Medicine, Iowa City, United States
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Praissman JL, Wells L. Mammalian O-mannosylation pathway: glycan structures, enzymes, and protein substrates. Biochemistry 2014; 53:3066-78. [PMID: 24786756 PMCID: PMC4033628 DOI: 10.1021/bi500153y] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The
mammalian O-mannosylation pathway for protein post-translational
modification is intricately involved in modulating cell–matrix
interactions in the musculature and nervous system. Defects in enzymes
of this biosynthetic pathway are causative for multiple forms of congenital
muscular dystophy. The application of advanced genetic and biochemical
technologies has resulted in remarkable progress in this field over
the past few years, culminating with the publication of three landmark
papers in 2013 alone. In this review, we will highlight recent progress
focusing on the dramatic expansion of the set of genes known to be
involved in O-mannosylation and disease processes, the concurrent
acceleration of the rate of O-mannosylation pathway protein functional
assignments, the tremendous increase in the number of proteins now
known to be modified by O-mannosylation, and the recent progress in
protein O-mannose glycan quantification and site assignment. Also,
we attempt to highlight key outstanding questions raised by this abundance
of new information.
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Affiliation(s)
- Jeremy L Praissman
- Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, The University of Georgia , Athens, Georgia 30602, United States
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40
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Protein O-mannosylation is crucial for E-cadherin-mediated cell adhesion. Proc Natl Acad Sci U S A 2013; 110:21024-9. [PMID: 24297939 DOI: 10.1073/pnas.1316753110] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In recent years protein O-mannosylation has become a focus of attention as a pathomechanism underlying severe congenital muscular dystrophies associated with neuronal migration defects. A key feature of these disorders is the lack of O-mannosyl glycans on α-dystroglycan, resulting in abnormal basement membrane formation. Additional functions of O-mannosylation are still largely unknown. Here, we identify the essential cell-cell adhesion glycoprotein epithelial (E)-cadherin as an O-mannosylated protein and establish a functional link between O-mannosyl glycans and cadherin-mediated cell-cell adhesion. By genetically and pharmacologically blocking protein O-mannosyltransferases, we found that this posttranslational modification is essential for preimplantation development of the mouse embryo. O-mannosylation-deficient embryos failed to proceed from the morula to the blastocyst stage because of defects in the molecular architecture of cell-cell contact sites, including the adherens and tight junctions. Using mass spectrometry, we demonstrate that O-mannosyl glycans are present on E-cadherin, the major cell-adhesion molecule of blastomeres, and present evidence that this modification is generally conserved in cadherins. Further, the use of newly raised antibodies specific for an O-mannosyl-conjugated epitope revealed that these glycans are present on early mouse embryos. Finally, our cell-aggregation assays demonstrated that O-mannosyl glycans are crucial for cadherin-based cell adhesion. Our results redefine the significance of O-mannosylation in humans and other mammals, showing the immense impact of cadherins on normal as well as pathogenic cell behavior.
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Filges I, Nosova E, Bruder E, Tercanli S, Townsend K, Gibson WT, Röthlisberger B, Heinimann K, Hall JG, Gregory-Evans CY, Wasserman WW, Miny P, Friedman JM. Exome sequencing identifies mutations in KIF14 as a novel cause of an autosomal recessive lethal fetal ciliopathy phenotype. Clin Genet 2013; 86:220-8. [PMID: 24128419 DOI: 10.1111/cge.12301] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 09/29/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022]
Abstract
Gene discovery using massively parallel sequencing has focused on phenotypes diagnosed postnatally such as well-characterized syndromes or intellectual disability, but is rarely reported for fetal disorders. We used family-based whole-exome sequencing in order to identify causal variants for a recurrent pattern of an undescribed lethal fetal congenital anomaly syndrome. The clinical signs included intrauterine growth restriction (IUGR), severe microcephaly, renal cystic dysplasia/agenesis and complex brain and genitourinary malformations. The phenotype was compatible with a ciliopathy, but not diagnostic of any known condition. We hypothesized biallelic disruption of a gene leading to a defect related to the primary cilium. We identified novel autosomal recessive truncating mutations in KIF14 that segregated with the phenotype. Mice with autosomal recessive mutations in the same gene have recently been shown to have a strikingly similar phenotype. Genotype-phenotype correlations indicate that the function of KIF14 in cell division and cytokinesis can be linked to a role in primary cilia, supported by previous cellular and model organism studies of proteins that interact with KIF14. We describe the first human phenotype, a novel lethal ciliary disorder, associated with biallelic inactivating mutations in KIF14. KIF14 may also be considered a candidate gene for allelic viable ciliary and/or microcephaly phenotypes.
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Affiliation(s)
- I Filges
- Department of Medical Genetics, University of British Columbia, and Child and Family Research Institute, Vancouver, Canada; Division of Medical Genetics, Department of Biomedicine, University Hospital, Basel, Switzerland
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Gibbs EM, Horstick EJ, Dowling JJ. Swimming into prominence: the zebrafish as a valuable tool for studying human myopathies and muscular dystrophies. FEBS J 2013; 280:4187-97. [PMID: 23809187 DOI: 10.1111/febs.12412] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/07/2013] [Accepted: 06/20/2013] [Indexed: 11/28/2022]
Abstract
A new and exciting phase of muscle disease research has recently been entered. The application of next generation sequencing technology has spurred an unprecedented era of gene discovery for both myopathies and muscular dystrophies. Gene-based therapies for Duchenne muscular dystrophy have entered clinical trial, and several pathway-based therapies are doing so as well for a handful of muscle diseases. While many factors have aided the extraordinary developments in gene discovery and therapy development, the zebrafish model system has emerged as a vital tool in these advancements. In this review, we will highlight how the zebrafish has greatly aided in the identification of new muscle disease genes and in the recognition of novel therapeutic strategies. We will start with a general introduction to the zebrafish as a model, discuss the ways in which muscle disease can be modeled and analyzed in the fish, and conclude with observations from recent studies that highlight the power of the fish as a research tool for muscle disease.
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Affiliation(s)
- Elizabeth M Gibbs
- Departments of Neuroscience, Neurology and Pediatrics, University of Michigan Medical Center, Ann Arbor, MI, USA
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Affiliation(s)
- Bertrand Kleizen
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Sciences, Utrecht University, Netherlands
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Zhang P, Yang Y, Candiello J, Thorn TL, Gray N, Halfter WM, Hu H. Biochemical and biophysical changes underlie the mechanisms of basement membrane disruptions in a mouse model of dystroglycanopathy. Matrix Biol 2013; 32:196-207. [PMID: 23454088 DOI: 10.1016/j.matbio.2013.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 01/24/2013] [Accepted: 02/11/2013] [Indexed: 01/11/2023]
Abstract
Mutations in glycosyltransferases, such as protein O-mannose N-acetylglucosaminyltransferase 1 (POMGnT1), causes disruptions of basement membranes (BMs) that results in neuronal ectopias and muscular dystrophy. While the mutations diminish dystroglycan-mediated cell-ECM interactions, the cause and mechanism of BM disruptions remain unclear. In this study, we established an in vitro model to measure BM assembly on the surface of neural stem cells. Compared to control cells, the rate of BM assembly on POMGnT1 knockout neural stem cells was significantly reduced. Further, immunofluorescence staining and quantitative proteomic analysis of the inner limiting membrane (ILM), a BM of the retina, revealed that laminin-111 and nidogen-1 were reduced in POMGnT1 knockout mice. Finally, atomic force microscopy showed that the ILM from POMGnT1 knockout mice was thinner with an altered surface topography. The results combined demonstrate that reduced levels of key BM components cause physical changes that weaken the BM in POMGnT1 knockout mice. These changes are caused by a reduced rate of BM assembly during the developmental expansion of the neural tissue.
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Affiliation(s)
- Peng Zhang
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, USA
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Loibl M, Strahl S. Protein O-mannosylation: what we have learned from baker's yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2438-46. [PMID: 23434682 DOI: 10.1016/j.bbamcr.2013.02.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 02/05/2013] [Accepted: 02/10/2013] [Indexed: 01/06/2023]
Abstract
BACKGROUND Protein O-mannosylation is a vital type of glycosylation that is conserved among fungi, animals, and humans. It is initiated in the endoplasmic reticulum (ER) where the synthesis of the mannosyl donor substrate and the mannosyltransfer to proteins take place. O-mannosylation defects interfere with cell wall integrity and ER homeostasis in yeast, and define a pathomechanism of severe neuromuscular diseases in humans. SCOPE OF REVIEW On the molecular level, the O-mannosylation pathway and the function of O-mannosyl glycans have been characterized best in the eukaryotic model yeast Saccharomyces cerevisiae. In this review we summarize general features of protein O-mannosylation, including biosynthesis of the mannosyl donor, characteristics of acceptor substrates, and the protein O-mannosyltransferase machinery in the yeast ER. Further, we discuss the role of O-mannosyl glycans and address the question why protein O-mannosylation is essential for viability of yeast cells. GENERAL SIGNIFICANCE Understanding of the molecular mechanisms of protein O-mannosylation in yeast could lead to the development of novel antifungal drugs. In addition, transfer of the knowledge from yeast to mammals could help to develop diagnostic and therapeutic approaches in the frame of neuromuscular diseases. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Inamori KI, Hara Y, Willer T, Anderson ME, Zhu Z, Yoshida-Moriguchi T, Campbell KP. Xylosyl- and glucuronyltransferase functions of LARGE in α-dystroglycan modification are conserved in LARGE2. Glycobiology 2012; 23:295-302. [PMID: 23125099 PMCID: PMC3555503 DOI: 10.1093/glycob/cws152] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
LARGE-dependent modification enables α-dystroglycan (α-DG) to bind to its extracellular matrix ligands. Mutations in the LARGE gene and several others involved in O-mannosyl glycan synthesis have been identified in congenital and limb-girdle muscular dystrophies that are characterized by perturbed glycosylation and reduced ligand-binding affinity of α-DG. LARGE is a bifunctional glycosyltransferase that alternately transfers xylose and glucuronic acid, thereby generating the heteropolysaccharides on α-DG that confer its ligand binding. Although the LARGE paralog LARGE2 (also referred to as GYLTL1B) has likewise been shown to enhance the functional modification of α-DG in cultured cells, its enzymatic activities have not been identified. Here, we report that LARGE2 is also a bifunctional glycosyltransferase and compare its properties with those of LARGE. By means of a high-performance liquid chromatography-based enzymatic assay, we demonstrate that like LARGE, LARGE2 has xylosyltransferase (Xyl-T) and glucuronyltransferase (GlcA-T) activities, as well as polymerizing activity. Notably, however, the pH optima of the Xyl-T and GlcA-T of LARGE2 are distinct from one another and also from those of LARGE. Our results suggest that LARGE and LARGE2 catalyze the same glycosylation reactions for the functional modification of α-DG, but that they have different biochemical properties.
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Affiliation(s)
- Kei-ichiro Inamori
- Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242-1101, USA
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47
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Dobson CM, Hempel SJ, Stalnaker SH, Stuart R, Wells L. O-Mannosylation and human disease. Cell Mol Life Sci 2012; 70:2849-57. [PMID: 23115008 DOI: 10.1007/s00018-012-1193-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/02/2012] [Accepted: 10/08/2012] [Indexed: 12/21/2022]
Abstract
Glycosylation of proteins is arguably the most prevalent co- and post-translational modification. It is responsible for increased heterogeneity and functional diversity of proteins. Here we discuss the importance of one type of glycosylation, specifically O-mannosylation and its relationship to a number of human diseases. The most widely studied O-mannose modified protein is alpha-dystroglycan (α-DG). Recent studies have focused intensely on α-DG due to the severity of diseases associated with its improper glycosylation. O-mannosylation of α-DG is involved in cancer metastasis, arenavirus entry, and multiple forms of congenital muscular dystrophy [1, 2]. In this review, we discuss the structural and functional characteristics of O-mannose-initiated glycan structures on α-DG, enzymes involved in the O-mannosylation pathway, and the diseases that are a direct result of disruptions within this pathway.
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Affiliation(s)
- Christina M Dobson
- Department of Biochemistry and Molecular Biology, Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
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48
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Tanner W, Lehle L. More than 40 years of glycobiology in Regensburg. Biochem Biophys Res Commun 2012; 425:578-582. [PMID: 22925677 DOI: 10.1016/j.bbrc.2012.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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49
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Beedle AM, Turner AJ, Saito Y, Lueck JD, Foltz SJ, Fortunato MJ, Nienaber PM, Campbell KP. Mouse fukutin deletion impairs dystroglycan processing and recapitulates muscular dystrophy. J Clin Invest 2012; 122:3330-42. [PMID: 22922256 DOI: 10.1172/jci63004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 06/21/2012] [Indexed: 11/17/2022] Open
Abstract
Dystroglycan is a transmembrane glycoprotein that links the extracellular basement membrane to cytoplasmic dystrophin. Disruption of the extensive carbohydrate structure normally present on α-dystroglycan causes an array of congenital and limb girdle muscular dystrophies known as dystroglycanopathies. The essential role of dystroglycan in development has hampered elucidation of the mechanisms underlying dystroglycanopathies. Here, we developed a dystroglycanopathy mouse model using inducible or muscle-specific promoters to conditionally disrupt fukutin (Fktn), a gene required for dystroglycan processing. In conditional Fktn-KO mice, we observed a near absence of functionally glycosylated dystroglycan within 18 days of gene deletion. Twenty-week-old KO mice showed clear dystrophic histopathology and a defect in glycosylation near the dystroglycan O-mannose phosphate, whether onset of Fktn excision driven by muscle-specific promoters occurred at E8 or E17. However, the earlier gene deletion resulted in more severe phenotypes, with a faster onset of damage and weakness, reduced weight and viability, and regenerating fibers of smaller size. The dependence of phenotype severity on the developmental timing of muscle Fktn deletion supports a role for dystroglycan in muscle development or differentiation. Moreover, given that this conditional Fktn-KO mouse allows the generation of tissue- and timing-specific defects in dystroglycan glycosylation, avoids embryonic lethality, and produces a phenotype resembling patient pathology, it is a promising new model for the study of secondary dystroglycanopathy.
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Affiliation(s)
- Aaron M Beedle
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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50
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The dystrophin–glycoprotein complex in brain development and disease. Trends Neurosci 2012; 35:487-96. [DOI: 10.1016/j.tins.2012.04.004] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 04/03/2012] [Accepted: 04/15/2012] [Indexed: 11/23/2022]
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