1
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Jahncke JN, Wright KM. The many roles of dystroglycan in nervous system development and function: Dystroglycan and neural circuit development: Dystroglycan and neural circuit development. Dev Dyn 2023; 252:61-80. [PMID: 35770940 DOI: 10.1002/dvdy.516] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 01/04/2023] Open
Abstract
The glycoprotein dystroglycan was first identified in muscle, where it functions as part of the dystrophin glycoprotein complex to connect the extracellular matrix to the actin cytoskeleton. Mutations in genes involved in the glycosylation of dystroglycan cause a form of congenital muscular dystrophy termed dystroglycanopathy. In addition to its well-defined role in regulating muscle integrity, dystroglycan is essential for proper central and peripheral nervous system development. Patients with dystroglycanopathy can present with a wide range of neurological perturbations, but unraveling the complex role of Dag1 in the nervous system has proven to be a challenge. Over the past two decades, animal models of dystroglycanopathy have been an invaluable resource that has allowed researchers to elucidate dystroglycan's many roles in neural circuit development. In this review, we summarize the pathways involved in dystroglycan's glycosylation and its known interacting proteins, and discuss how it regulates neuronal migration, axon guidance, synapse formation, and its role in non-neuronal cells.
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Affiliation(s)
- Jennifer N Jahncke
- Neuroscience Graduate Program, Oregan Health & Science University, Portland, Oregon, USA
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science University, Portland, Oregon, USA
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2
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The Synthesis of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine Kinase (GNE), α-dystroglycan, and β-galactoside α-2,3-sialyltransferase 6 (ST3Gal6) By Skeletal Muscle Cell As a Response To Infection with Trichinella Spiralis. Helminthologia 2022; 59:217-225. [PMID: 36694833 PMCID: PMC9831521 DOI: 10.2478/helm-2022-0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 08/17/2022] [Indexed: 12/23/2022] Open
Abstract
The Nurse cell of the parasitic nematode Trichinella spiralis is a unique structure established after genetic, morphological and functional modification of a small portion of invaded skeletal muscle fiber. Even if the newly developed cytoplasm of the Nurse cell is no longer contractile, this structure remains well integrated within the surrounding healthy tissue. Our previous reports suggested that this process is accompanied by an increased local biosynthesis of sialylated glycoproteins. In this work we examined the expressions of three proteins, functionally associated with the process of sialylation. The enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) is a key initiator of the sialic acid biosynthetic pathway. The α-dystroglycan was the only identified sialylated glycoprotein in skeletal muscles by now, bearing sialyl-α-2,3-Gal-β-1,4-Gl-cNAc-β-1,2-Man-α-1-O-Ser/Thr glycan. The third protein of interest for this study was the enzyme β-galactoside α-2,3-sialyltransferase 6 (ST3Gal6), which transfers sialic acid preferably onto Gal-β-1,4-GlcNAc as an acceptor, and thus it was considered as a suitable candidate for the sialylation of the α-dystroglycan. The expressions of the three proteins were analyzed by real time-PCR and immunohistochemistry on modified methacarn fixed paraffin tissue sections of mouse skeletal muscle samples collected at days 0, 14 and 35 post infection. According to our findings, the up-regulation of GNE was a characteristic of the early and the late stage of the Nurse cell development. Additional features of this process were the elevated expressions of α-dystroglycan and the enzyme ST3Gal6. We provided strong evidence that an increased local synthesis of sialic acids is a trait of the Nurse cell of T. spiralis, and at least in part due to an overexpression of α-dystroglycan. In addition, circumstantially we suggest that the enzyme ST3Gal6 is engaged in the process of sialylation of the major oligosaccharide component of α-dystroglycan.
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3
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Milcheva RS, Janega P, Petkova SL, Todorova KS, Ivanov DG, Babál P. Absence of ST3Gal2 and ST3Gal4 sialyltransferase expressions in the nurse cell of Trichinella spiralis. BULGARIAN JOURNAL OF VETERINARY MEDICINE 2022. [DOI: 10.15547/bjvm.2020-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study was aimed to describe some glycosylation changes in the Nurse cell of Trichinella spiralis in mouse skeletal muscle. Tissue specimens were subjected to lectin histochemistry with Maackia amurensis lectin (MAL), Peanut agglutinin (PNA) and neuraminidase desialylation in order to verify and analyse the structure of α-2,3-sialylated glycoproteins, discovered within the affected sarcoplasm. The expressions of two sialyltransferases were examined by immunohistochemistry. It was found out that the occupied portion of skeletal muscle cell responded with synthesis of presumable sialyl-T-antigen and α-2,3-sialyllactosamine structure, that remained accumulated during the time course of Nurse cell development. The enzymes β-galactoside-α-2,3-sialyltransferases 2 and 4, which could be responsible for the sialylation of each of these structures, were however not present in the invaded muscle portions, although their expressions in the healthy surrounding tissue remained persistent. Our results contribute to the progressive understanding about the amazing abilities of Trichinella spiralis to manipulate the genetic programme of its host.
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Affiliation(s)
- R. S. Milcheva
- Institute of Experimental Morphology, Pathology and Anthropology with Museum – Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - P. Janega
- Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Bratislava, Slovakia
| | - S. L. Petkova
- Institute of Experimental Morphology, Pathology and Anthropology with Museum – Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - K. S. Todorova
- Institute of Experimental Morphology, Pathology and Anthropology with Museum – Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - D. G. Ivanov
- Institute of Experimental Morphology, Pathology and Anthropology with Museum – Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - P. Babál
- Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Bratislava, Slovakia
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4
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Marini M, Tani A, Manetti M, Sgambati E. Overview of sialylation status in human nervous and skeletal muscle tissues during aging. Acta Histochem 2021; 123:151813. [PMID: 34753032 DOI: 10.1016/j.acthis.2021.151813] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/29/2021] [Accepted: 10/29/2021] [Indexed: 12/14/2022]
Abstract
Sialic acids (Sias) are a large and heterogeneous family of electronegatively charged nine-carbon monosaccharides containing a carboxylic acid and are mostly found as terminal residues in glycans of glycoproteins and glycolipids such as gangliosides. They are linked to galactose or N-acetylgalactosamine via α2,3 or α2,6 linkage, or to other Sias via α2,8 or more rarely α2,9 linkage, resulting in mono, oligo and polymeric forms. Given their characteristics, Sias play a crucial role in a multitude of human tissue biological processes in physiological and pathological conditions, ranging from development and growth to adult life until aging. Here, we review the sialylation status in human adult life focusing on the nervous and skeletal muscle tissues, which both display significant structural and functional changes during aging, strongly impacting on the whole human body and, therefore, on the quality of life. In particular, this review highlights the fundamental roles played by different types of glycoconjugates Sias in several cellular biological processes in the nervous and skeletal muscle tissues during adult life, also discussing how changes in Sia content during aging may contribute to the physiological decline of physical and nervous functions and to the development of age-related degenerative pathologies. Based on our current knowledge, further in-depth investigations could help to develop novel prophylactic strategies and therapeutic approaches that, by maintaining and/or restoring the correct sialylation status in the nervous and skeletal muscle tissues, could contribute to aging slowing and the prevention of age-related pathologies.
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5
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Zhang KY, Johnson TV. The internal limiting membrane: Roles in retinal development and implications for emerging ocular therapies. Exp Eye Res 2021; 206:108545. [PMID: 33753089 DOI: 10.1016/j.exer.2021.108545] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/02/2021] [Accepted: 03/16/2021] [Indexed: 12/17/2022]
Abstract
Basement membranes help to establish, maintain, and separate their associated tissues. They also provide growth and signaling substrates for nearby resident cells. The internal limiting membrane (ILM) is the basement membrane at the ocular vitreoretinal interface. While the ILM is essential for normal retinal development, it is dispensable in adulthood. Moreover, the ILM may constitute a significant barrier to emerging ocular therapeutics, such as viral gene therapy or stem cell transplantation. Here we take a neurodevelopmental perspective in examining how retinal neurons, glia, and vasculature interact with individual extracellular matrix constituents at the ILM. In addition, we review evidence that the ILM may impede novel ocular therapies and discuss approaches for achieving retinal parenchymal targeting of gene vectors and cell transplants delivered into the vitreous cavity by manipulating interactions with the ILM.
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Affiliation(s)
- Kevin Y Zhang
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA
| | - Thomas V Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Maumenee B-110, Baltimore, MD, 21287, USA.
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6
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Yatsenko AS, Kucherenko MM, Xie Y, Urlaub H, Shcherbata HR. Exocyst-mediated membrane trafficking of the lissencephaly-associated ECM receptor dystroglycan is required for proper brain compartmentalization. eLife 2021; 10:63868. [PMID: 33620318 PMCID: PMC7929561 DOI: 10.7554/elife.63868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 02/23/2021] [Indexed: 12/14/2022] Open
Abstract
To assemble a brain, differentiating neurons must make proper connections and establish specialized brain compartments. Abnormal levels of cell adhesion molecules disrupt these processes. Dystroglycan (Dg) is a major non-integrin cell adhesion receptor, deregulation of which is associated with dramatic neuroanatomical defects such as lissencephaly type II or cobblestone brain. The previously established Drosophila model for cobblestone lissencephaly was used to understand how Dg is regulated in the brain. During development, Dg has a spatiotemporally dynamic expression pattern, fine-tuning of which is crucial for accurate brain assembly. In addition, mass spectrometry analyses identified numerous components associated with Dg in neurons, including several proteins of the exocyst complex. Data show that exocyst-based membrane trafficking of Dg allows its distinct expression pattern, essential for proper brain morphogenesis. Further studies of the Dg neuronal interactome will allow identification of new factors involved in the development of dystroglycanopathies and advance disease diagnostics in humans.
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Affiliation(s)
- Andriy S Yatsenko
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariya M Kucherenko
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Yuanbin Xie
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Research Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,University Medical Center Göttingen, Bioanalytics, Institute for Clinical Chemistry, Göttingen, Germany
| | - Halyna R Shcherbata
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany.,Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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7
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Sheikh MO, Venzke D, Anderson ME, Yoshida-Moriguchi T, Glushka JN, Nairn AV, Galizzi M, Moremen KW, Campbell KP, Wells L. HNK-1 sulfotransferase modulates α-dystroglycan glycosylation by 3-O-sulfation of glucuronic acid on matriglycan. Glycobiology 2020; 30:817-829. [PMID: 32149355 DOI: 10.1093/glycob/cwaa024] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 02/26/2020] [Accepted: 02/26/2020] [Indexed: 12/18/2022] Open
Abstract
Mutations in multiple genes required for proper O-mannosylation of α-dystroglycan are causal for congenital/limb-girdle muscular dystrophies and abnormal brain development in mammals. Previously, we and others further elucidated the functional O-mannose glycan structure that is terminated by matriglycan, [(-GlcA-β3-Xyl-α3-)n]. This repeating disaccharide serves as a receptor for proteins in the extracellular matrix. Here, we demonstrate in vitro that HNK-1 sulfotransferase (HNK-1ST/carbohydrate sulfotransferase) sulfates terminal glucuronyl residues of matriglycan at the 3-hydroxyl and prevents further matriglycan polymerization by the LARGE1 glycosyltransferase. While α-dystroglycan isolated from mouse heart and kidney is susceptible to exoglycosidase digestion of matriglycan, the functional, lower molecular weight α-dystroglycan detected in brain, where HNK-1ST expression is elevated, is resistant. Removal of the sulfate cap by a sulfatase facilitated dual-glycosidase digestion. Our data strongly support a tissue specific mechanism in which HNK-1ST regulates polymer length by competing with LARGE for the 3-position on the nonreducing GlcA of matriglycan.
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Affiliation(s)
- M Osman Sheikh
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - David Venzke
- Department of Molecular Physiology and Biophysics, Department of Neurology, Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Mary E Anderson
- Department of Molecular Physiology and Biophysics, Department of Neurology, Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Takako Yoshida-Moriguchi
- Department of Molecular Physiology and Biophysics, Department of Neurology, Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - John N Glushka
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Alison V Nairn
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Melina Galizzi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Kevin P Campbell
- Department of Molecular Physiology and Biophysics, Department of Neurology, Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Lance Wells
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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8
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Milcheva R, Janega P, Celec P, Petkova S, Hurniková Z, Izrael-Vlková B, Todorova K, Babál P. Accumulation of α-2,6-sialyoglycoproteins in the Muscle Sarcoplasm Due to Trichinella Sp. Invasion. Open Life Sci 2019; 14:470-481. [PMID: 33817183 PMCID: PMC7874827 DOI: 10.1515/biol-2019-0053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/30/2019] [Indexed: 01/02/2023] Open
Abstract
The sialylation of the glycoproteins in skeletal muscle tissue is not well investigated, even though the essential role of the sialic acids for the proper muscular function has been proven by many researchers. The invasion of the parasitic nematode Trichinella spiralis in the muscles with subsequent formation of Nurse cell-parasite complex initiates increased accumulation of sialylated glycoproteins within the affected area of the muscle fiber. The aim of this study is to describe some details of the α-2,6-sialylation in invaded muscle cells. Asynchronous invasion with infectious T. spiralis larvae was experimentally induced in mice. The areas of the occupied sarcoplasm were reactive towards α-2,6-sialic acid specific Sambucus nigra agglutinin during the whole process of transformation to a Nurse cell.The cytoplasm of the developing Nurse cell reacted with Helix pomatia agglutinin, Arachis hypogea agglutinin and Vicia villosa lectin-B4 after neuraminidase pretreatment.Up-regulation of the enzyme ST6GalNAc1 and down-regulation of the enzyme ST6GalNAc3 were detected throughout the course of this study. The results from our study assumed accumulation of sialyl-Tn-Ag, 6`-sialyl lactosamine, SiA-α-2,6-Gal-β-1,3-GalNAc-α-Ser/Thr and Gal-β-1,3-GalNAc(SiA-α-2,6-)-α-1-Ser/Thr oligosaccharide structures into the occupied sarcoplasm. Further investigations in this domain will develop the understanding about the amazing adaptive capabilities of skeletal muscle tissue.
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Affiliation(s)
- Rositsa Milcheva
- Department of Pathology, IEMPAM, Bulgarian Academy of Sciences, ‘’Acad. G. Bonchev’’ Str. 25, 1113, Sofia, Bulgaria
- Institute of Experimental Morphology, Pathology and Anthropology with Museum (IEMPAM), Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str. 25, 1113Sofia, Bulgaria
| | - Pavol Janega
- Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Sasinkova 4, 81372Bratislava, Slovakia
| | - Peter Celec
- Department of Molecular Biomedicine, Faculty of Medicine, Comenius University in Bratislava, Sasinkova 4, 81372Bratislava, Slovakia
| | - Svetlozara Petkova
- Institute of Experimental Morphology, Pathology and Anthropology with Museum (IEMPAM), Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str. 25, 1113Sofia, Bulgaria
| | - Zuzana Hurniková
- Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, 040 01Košice, Slovak Republic
| | - Barbora Izrael-Vlková
- Department of Molecular Biomedicine, Faculty of Medicine, Comenius University in Bratislava, Sasinkova 4, 81372Bratislava, Slovakia
| | - Katerina Todorova
- Institute of Experimental Morphology, Pathology and Anthropology with Museum (IEMPAM), Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str. 25, 1113Sofia, Bulgaria
| | - Pavel Babál
- Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Sasinkova 4, 81372Bratislava, Slovakia
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9
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Structural basis of laminin binding to the LARGE glycans on dystroglycan. Nat Chem Biol 2016; 12:810-4. [PMID: 27526028 PMCID: PMC5030134 DOI: 10.1038/nchembio.2146] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/17/2016] [Indexed: 12/12/2022]
Abstract
Dystroglycan is a highly glycosylated extracellular matrix receptor with essential functions in skeletal muscle and the nervous system. Reduced matrix binding by α-dystroglycan (α-DG) due to perturbed glycosylation is a pathological feature of several forms of muscular dystrophy. Like-acetylglucosaminyltransferase (LARGE) synthesizes the matrix-binding heteropolysaccharide [-glucuronic acid-β1,3-xylose-α1,3-]n. Using a dual exoglycosidase digestion, we confirm that this polysaccharide is present on native α-DG from skeletal muscle. The atomic details of matrix binding were revealed by a high-resolution crystal structure of laminin G-like (LG) domains 4-5 of laminin α2 bound to a LARGE-synthesized oligosaccharide. A single glucuronic acid-β1,3-xylose disaccharide repeat straddles a Ca2+ ion in the LG4 domain, with oxygen atoms from both sugars replacing Ca2+-bound water molecules. The chelating binding mode accounts for the high affinity of this protein-carbohydrate interaction. These results reveal a novel mechanism of carbohydrate recognition and provide a structural framework for elucidating the mechanisms underlying muscular dystrophy.
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10
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Li S, Qi Y, McKee K, Liu J, Hsu J, Yurchenco PD. Integrin and dystroglycan compensate each other to mediate laminin-dependent basement membrane assembly and epiblast polarization. Matrix Biol 2016; 57-58:272-284. [PMID: 27449702 DOI: 10.1016/j.matbio.2016.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/15/2016] [Accepted: 07/15/2016] [Indexed: 01/17/2023]
Abstract
During early embryogenesis, endodermal γ1-laminin expression is required for basement membrane (BM) assembly, promoting conversion of non-polar pluripotent cells into polarized epiblast. The influence of laminin-111 (Lm111) and its integrin and dystroglycan (DG) receptors on epiblast in embryoid bodies (EBs), a model for differentiation of the embryonic plate, was further investigated. Lm111 added to the medium of EBs initiated conversion of inner nonpolar cell to the polarized epiblast epithelium with an exterior-to-central basal-to-apical orientation. Microinjection of Lm111 into EB interiors resulted in an interior BM with complete inversion of cell polarity. Lm111 assembled a BM on integrin-β1 null EBs with induction of polarization at reduced efficiency. β-Integrin compensation was not detected in these nulls with integrin adaptor proteins failing to assemble. A dimer of laminin LG domains 4-5 (LZE3) engineered to strongly bind to α-dystroglycan almost completely inhibited laminin accumulation on integrin β1-null EBs, reducing BM and ablating cell polarization. When Lm111 was incubated with integrin-β1/dystroglycan double-knockout EBs, laminin failed to accumulate on the EBs, the EBs did not differentiate, and the EBs underwent apoptosis. Collectively the findings support the hypotheses that the locus of laminin cell surface assembly can determine the axis of epithelial polarity. This requires integrin- and/or dystroglycan-dependent binding to laminin LG domains with the highest efficiency achieved when both receptors are present. Finally, EBs that cannot assemble a matrix undergo apoptosis.
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Affiliation(s)
- Shaohua Li
- Department of Surgery, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA; Department of Pathology & Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
| | - Yanmei Qi
- Department of Surgery, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Karen McKee
- Department of Pathology & Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Jie Liu
- Department of Surgery, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - June Hsu
- Department of Surgery, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Peter D Yurchenco
- Department of Pathology & Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
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11
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Gerin I, Ury B, Breloy I, Bouchet-Seraphin C, Bolsée J, Halbout M, Graff J, Vertommen D, Muccioli GG, Seta N, Cuisset JM, Dabaj I, Quijano-Roy S, Grahn A, Van Schaftingen E, Bommer GT. ISPD produces CDP-ribitol used by FKTN and FKRP to transfer ribitol phosphate onto α-dystroglycan. Nat Commun 2016; 7:11534. [PMID: 27194101 PMCID: PMC4873967 DOI: 10.1038/ncomms11534] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/06/2016] [Indexed: 01/27/2023] Open
Abstract
Mutations in genes required for the glycosylation of α-dystroglycan lead to muscle and brain diseases known as dystroglycanopathies. However, the precise structure and biogenesis of the assembled glycan are not completely understood. Here we report that three enzymes mutated in dystroglycanopathies can collaborate to attach ribitol phosphate onto α-dystroglycan. Specifically, we demonstrate that isoprenoid synthase domain-containing protein (ISPD) synthesizes CDP-ribitol, present in muscle, and that both recombinant fukutin (FKTN) and fukutin-related protein (FKRP) can transfer a ribitol phosphate group from CDP-ribitol to α-dystroglycan. We also show that ISPD and FKTN are essential for the incorporation of ribitol into α-dystroglycan in HEK293 cells. Glycosylation of α-dystroglycan in fibroblasts from patients with hypomorphic ISPD mutations is reduced. We observe that in some cases glycosylation can be partially restored by addition of ribitol to the culture medium, suggesting that dietary supplementation with ribitol should be evaluated as a therapy for patients with ISPD mutations.
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Affiliation(s)
- Isabelle Gerin
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Benoît Ury
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Isabelle Breloy
- Institute for Biochemistry II, Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Céline Bouchet-Seraphin
- AP-HP, Hôpital Bichat-Claude Bernard, Laboratoire de Biochimie Métabolique et Cellulaire, F-75018 Paris, France
| | - Jennifer Bolsée
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Mathias Halbout
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Julie Graff
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Didier Vertommen
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Giulio G Muccioli
- Louvain Drug Research Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Nathalie Seta
- AP-HP, Hôpital Bichat-Claude Bernard, Laboratoire de Biochimie Métabolique et Cellulaire, F-75018 Paris, France
| | - Jean-Marie Cuisset
- Hôpital Roger-Salengro, Service de neuropédiatrie, Centre de Référence des Maladies Neuromusculaires, CHRU, F-59000 Lille, France
| | - Ivana Dabaj
- AP-HP, Hôpital R Poincaré, Service de pédiatrie, F-92380 Garches, France
| | - Susana Quijano-Roy
- AP-HP, Hôpital R Poincaré, Service de pédiatrie, F-92380 Garches, France.,Centre de Référence des Maladies Neuromusculaires, F-92380 Garches, France.,Université de Versailles-St Quentin, U1179 UVSQ - INSERM, F-78180 Montigny, France
| | - Ammi Grahn
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Emile Van Schaftingen
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
| | - Guido T Bommer
- WELBIO and de Duve Institute, Biological Chemistry, Université Catholique de Louvain, B-1200 Brussels, Belgium
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12
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Dystroglycan Depletion Impairs Actin-Dependent Functions of Differentiated Kasumi-1 Cells. PLoS One 2015; 10:e0144078. [PMID: 26630171 PMCID: PMC4668107 DOI: 10.1371/journal.pone.0144078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 11/12/2015] [Indexed: 01/20/2023] Open
Abstract
Background Dystroglycan has recently been characterised in blood tissue cells, as part of the dystrophin glycoprotein complex involved in the differentiation process of neutrophils. Purpose In the present study we have investigated the role of dystroglycan in the human promyelocytic leukemic cell line Kasumi-1 differentiated to macrophage-like cells. Methods We characterised the pattern expression and subcellular distribution of dystroglycans in non-differentiated and differentiated Kasumi-1 cells. Results Our results demonstrated by WB and flow cytometer assays that during the differentiation process to macrophages, dystroglycans were down-regulated; these results were confirmed with qRT-PCR assays. Additionally, depletion of dystroglycan by RNAi resulted in altered morphology and reduced properties of differentiated Kasumi-1 cells, including morphology, migration and phagocytic activities although secretion of IL-1β and expression of markers of differentiation are not altered. Conclusion Our findings strongly implicate dystroglycan as a key membrane adhesion protein involved in actin-based structures during the differentiation process in Kasumi-1 cells.
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Human ISPD Is a Cytidyltransferase Required for Dystroglycan O-Mannosylation. ACTA ACUST UNITED AC 2015; 22:1643-52. [DOI: 10.1016/j.chembiol.2015.10.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/24/2015] [Accepted: 10/13/2015] [Indexed: 01/03/2023]
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14
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Milcheva R, Ivanov D, Iliev I, Russev R, Petkova S, Babal P. Increased sialylation as a phenomenon in accommodation of the parasitic nematode Trichinella spiralis (Owen, 1835) in skeletal muscle fibres. Folia Parasitol (Praha) 2015; 62. [PMID: 26373236 DOI: 10.14411/fp.2015.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 07/01/2015] [Indexed: 01/09/2023]
Abstract
The biology of sialic acids has been an object of interest in many models of acquired and inherited skeletal muscle pathology. The present study focuses on the sialylation changes in mouse skeletal muscle after invasion by the parasitic nematode Trichinella spiralis (Owen, 1835). Asynchronous infection with T. spiralis was induced in mice that were sacrificed at different time points of the muscle phase of the disease. The amounts of free sialic acid, sialylated glycoproteins and total sialyltransferase activity were quantified. Histochemistry with lectins specific for sialic acid was performed in order to localise distribution of sialylated glycoconjugates and to clarify the type of linkage of the sialic acid residues on the carbohydrate chains. Elevated intracellular accumulation of α-2,3- and α-2,6-sialylated glycoconjugates was found only within the affected sarcoplasm of muscle fibres invaded by the parasite. The levels of free and protein-bound sialic acid were increased and the total sialyltransferase activity was also elevated in the skeletal muscle tissue of animals with trichinellosis. We suggest that the biological significance of this phenomenon might be associated with securing integrity of the newly formed nurse cell within the surrounding healthy skeletal muscle tissue. The increased sialylation might inhibit the affected muscle cell contractility through decreased membrane ion gating, helping the parasite accommodation process.
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Affiliation(s)
- Rositsa Milcheva
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria.,Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Bratislava, Slovakia
| | - Dimitar Ivanov
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Ivan Iliev
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Russy Russev
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Svetlozara Petkova
- Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Pavel Babal
- Department of Pathology, Faculty of Medicine, Comenius University in Bratislava, Bratislava, Slovakia
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15
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Yoshida-Moriguchi T, Campbell KP. Matriglycan: a novel polysaccharide that links dystroglycan to the basement membrane. Glycobiology 2015; 25:702-13. [PMID: 25882296 PMCID: PMC4453867 DOI: 10.1093/glycob/cwv021] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 04/08/2015] [Indexed: 01/01/2023] Open
Abstract
Associations between cells and the basement membrane are critical for a variety of biological events including cell proliferation, cell migration, cell differentiation and the maintenance of tissue integrity. Dystroglycan is a highly glycosylated basement membrane receptor, and is involved in physiological processes that maintain integrity of the skeletal muscle, as well as development and function of the central nervous system. Aberrant O-glycosylation of the α subunit of this protein, and a concomitant loss of dystroglycan's ability to function as a receptor for extracellular matrix (ECM) ligands that bear laminin globular (LG) domains, occurs in several congenital/limb-girdle muscular dystrophies (also referred to as dystroglycanopathies). Recent genetic studies revealed that mutations in DAG1 (which encodes dystroglycan) and at least 17 other genes disrupt the ECM receptor function of dystroglycan and cause disease. Here, we summarize recent advances in our understanding of the enzymatic functions of two of these disease genes: the like-glycosyltransferase (LARGE) and protein O-mannose kinase (POMK, previously referred to as SGK196). In addition, we discuss the structure of the glycan that directly binds the ECM ligands and the mechanisms by which this functional motif is linked to dystroglycan. In light of the fact that dystroglycan functions as a matrix receptor and the polysaccharide synthesized by LARGE is the binding motif for matrix proteins, we propose to name this novel polysaccharide structure matriglycan.
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Affiliation(s)
- Takako Yoshida-Moriguchi
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242-1101, USA
| | - Kevin P Campbell
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242-1101, USA
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16
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17
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Riemersma M, Sandrock J, Boltje TJ, Büll C, Heise T, Ashikov A, Adema GJ, van Bokhoven H, Lefeber DJ. Disease mutations in CMP-sialic acid transporter SLC35A1 result in abnormal α-dystroglycan O-mannosylation, independent from sialic acid. Hum Mol Genet 2014; 24:2241-6. [PMID: 25552652 DOI: 10.1093/hmg/ddu742] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Binding of cellular α-dystroglycan (α-DG) to its extracellular matrix ligands is fully dependent on a unique O-mannose-linked glycan. Disrupted O-mannosylation is the hallmark of the muscular dystrophy-dystroglycanopathy (MDDG) syndromes. SLC35A1, encoding the transporter of cytidine 5'-monophosphate-sialic acid, was recently identified as MDDG candidate gene. This is surprising, since sialic acid itself is dispensable for α-DG-ligand binding. In a novel SLC35A1-deficient cell model, we demonstrated a lack of α-DG O-mannosylation, ligand binding and incorporation of sialic acids. Removal of sialic acids from HAP1 wild-type cells after incorporation or preventing sialylation during synthesis did not affect α-DG O-mannosylation or ligand binding but did affect sialylation. Lentiviral-mediated complementation with the only known disease mutation p.Q101H failed to restore deficient O-mannosylation in SLC35A1 knockout cells and partly restored sialylation. These data indicate a role for SLC35A1 in α-DG O-mannosylation that is distinct from sialic acid metabolism. In addition, human SLC35A1 deficiency can be considered as a combined disorder of α-DG O-mannosylation and sialylation, a novel variant of the MDDG syndromes.
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Affiliation(s)
- Moniek Riemersma
- Department of Neurology, Translational Metabolic Laboratory, Department of Laboratory Medicine, Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Julia Sandrock
- Department of Neurology, Translational Metabolic Laboratory, Department of Laboratory Medicine
| | - Thomas J Boltje
- Cluster for Molecular Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Christian Büll
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands and
| | - Torben Heise
- Cluster for Molecular Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Angel Ashikov
- Department of Neurology, Translational Metabolic Laboratory, Department of Laboratory Medicine
| | - Gosse J Adema
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands and
| | - Hans van Bokhoven
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands, Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Dirk J Lefeber
- Department of Neurology, Translational Metabolic Laboratory, Department of Laboratory Medicine,
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18
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miRNA-based buffering of the cobblestone-lissencephaly-associated extracellular matrix receptor dystroglycan via its alternative 3'-UTR. Nat Commun 2014; 5:4906. [PMID: 25232965 PMCID: PMC4199286 DOI: 10.1038/ncomms5906] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 08/02/2014] [Indexed: 11/08/2022] Open
Abstract
Many proteins are expressed dynamically during different stages of cellular life and the accuracy of protein amounts is critical for cell endurance. Therefore, cells should have a perceptive system that notifies about fluctuations in the amounts of certain components and an executive system that efficiently restores their precise levels. At least one mechanism that evolution has employed for this task is regulation of 3'-UTR length for microRNA targeting. Here we show that in Drosophila the microRNA complex miR-310s acts as an executive mechanism to buffer levels of the muscular dystrophy-associated extracellular matrix receptor dystroglycan via its alternative 3'-UTR. miR-310s gene expression fluctuates depending on dystroglycan amounts and nitric oxide signalling, which perceives dystroglycan levels and regulates microRNA gene expression. Aberrant levels of dystroglycan or deficiencies in miR-310s and nitric oxide signalling result in cobblestone brain appearance, resembling human lissencephaly type II phenotype.
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19
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Townsend D. Finding the sweet spot: assembly and glycosylation of the dystrophin-associated glycoprotein complex. Anat Rec (Hoboken) 2014; 297:1694-705. [PMID: 25125182 PMCID: PMC4135523 DOI: 10.1002/ar.22974] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/27/2014] [Indexed: 01/12/2023]
Abstract
The dystrophin-associated glycoprotein complex (DGC) is a collection of glycoproteins that are essential for the normal function of striated muscle and many other tissues. Recent genetic studies have implicated the components of this complex in over a dozen forms of muscular dystrophy. Furthermore, disruption of the DGC has been implicated in many forms of acquired disease. This review aims to summarize the current state of knowledge regarding the processing and assembly of dystrophin-associated proteins with a focus primarily on the dystroglycan heterodimer and the sarcoglycan complex. These proteins form the transmembrane portion of the DGC and undergo a complex multi-step processing with proteolytic cleavage, differential assembly, and both N- and O-glycosylation. The enzymes responsible for this processing and a model describing the sequence and subcellular localization of these events are discussed.
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Affiliation(s)
- Dewayne Townsend
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
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20
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Swiderski K, Shaffer SA, Gallis B, Odom GL, Arnett AL, Scott Edgar J, Baum DM, Chee A, Naim T, Gregorevic P, Murphy KT, Moody J, Goodlett DR, Lynch GS, Chamberlain JS. Phosphorylation within the cysteine-rich region of dystrophin enhances its association with β-dystroglycan and identifies a potential novel therapeutic target for skeletal muscle wasting. Hum Mol Genet 2014; 23:6697-711. [PMID: 25082828 DOI: 10.1093/hmg/ddu388] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in dystrophin lead to Duchenne muscular dystrophy, which is among the most common human genetic disorders. Dystrophin nucleates assembly of the dystrophin-glycoprotein complex (DGC), and a defective DGC disrupts an essential link between the intracellular cytoskeleton and the basal lamina, leading to progressive muscle wasting. In vitro studies have suggested that dystrophin phosphorylation may affect interactions with actin or syntrophin, yet whether this occurs in vivo or affects protein function remains unknown. Utilizing nanoflow liquid chromatography mass spectrometry, we identified 18 phosphorylated residues within endogenous dystrophin. Mutagenesis revealed that phosphorylation at S3059 enhances the dystrophin-dystroglycan interaction and 3D modeling utilizing the Rosetta software program provided a structural model for how phosphorylation enhances this interaction. These findings demonstrate that phosphorylation is a key mechanism regulating the interaction between dystrophin and the DGC and reveal that posttranslational modification of a single amino acid directly modulates the function of dystrophin.
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Affiliation(s)
- Kristy Swiderski
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195-7720, USA
| | - Scott A Shaffer
- Department of Medicinal Chemistry, University of Washington School of Medicine, Seattle, WA 98195-7610, USA
| | - Byron Gallis
- Department of Medicinal Chemistry, University of Washington School of Medicine, Seattle, WA 98195-7610, USA
| | - Guy L Odom
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195-7720, USA
| | - Andrea L Arnett
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195-7720, USA
| | - J Scott Edgar
- Department of Medicinal Chemistry, University of Washington School of Medicine, Seattle, WA 98195-7610, USA
| | - Dale M Baum
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia
| | - Annabel Chee
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia
| | - Timur Naim
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia
| | - Paul Gregorevic
- Muscle Biology and Therapeutics Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Kate T Murphy
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia
| | - James Moody
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195-7350, USA and Program in Molecular and Cellular Biology, University of Washington School of Medicine, Seattle, WA 98195-7275, USA
| | - David R Goodlett
- Department of Medicinal Chemistry, University of Washington School of Medicine, Seattle, WA 98195-7610, USA
| | - Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, VIC 3010, Australia
| | - Jeffrey S Chamberlain
- Department of Neurology, University of Washington School of Medicine, Seattle, WA 98195-7720, USA Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195-7350, USA and Program in Molecular and Cellular Biology, University of Washington School of Medicine, Seattle, WA 98195-7275, USA
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21
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Expression of sialic acids in human adult skeletal muscle tissue. Acta Histochem 2014; 116:926-35. [PMID: 24703356 DOI: 10.1016/j.acthis.2014.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 03/06/2014] [Accepted: 03/11/2014] [Indexed: 12/20/2022]
Abstract
Investigations mostly in animal models have shown a role of sialic acid in the morphology and functionality of skeletal muscle during development and adult life. Several studies in humans have been performed regarding changes in sialic acid expression in a particular pathology, hereditary inclusion body myopathy, leading to muscular weakness and atrophy, with a similar phenomenon appearing also in sarcopenia of aging. In this study the expression of monomeric and polymeric sialic acids was evaluated in human skeletal muscle during adult life. Surgical biopsies of the Quadriceps femoris muscle from men aged 18-25 years (young group; n=8) and men aged 72-78 (elderly group; n=10) were collected for analysis. Expression of sialic acids was evaluated using lectin histochemistry, associated with enzymatic and chemical treatments to characterize monomeric and polymeric sialic acids. The polysialic acid expression was also evaluated by immunohistochemistry. Various types of sialic acid in the muscle tissue, in different amounts in the study groups, were detected. Monomeric sialic acids decreased in the elderly group compared with the young group, whereas polysialic acid increased. Sialic acid acetylation was present only in the young group. These findings demonstrated that changes in the expression of sialic acids in skeletal muscle tissue may be related to morphofunctional modifications occurring during aging.
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22
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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: 51] [Impact Index Per Article: 5.1] [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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Vannoy CH, Xu L, Keramaris E, Lu P, Xiao X, Lu QL. Adeno-associated virus-mediated overexpression of LARGE rescues α-dystroglycan function in dystrophic mice with mutations in the fukutin-related protein. Hum Gene Ther Methods 2014; 25:187-96. [PMID: 24635668 DOI: 10.1089/hgtb.2013.151] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Multiple genes (e.g., POMT1, POMT2, POMGnT1, ISPD, GTDC2, B3GALNT2, FKTN, FKRP, and LARGE) are known to be involved in the glycosylation pathway of α-dystroglycan (α-DG). Mutations of these genes result in muscular dystrophies with wide phenotypic variability. Abnormal glycosylation of α-DG with decreased extracellular ligand binding activity is a common biochemical feature of these genetic diseases. While it is known that LARGE overexpression can compensate for defects in a few aforementioned genes, it is unclear whether it can also rescue defects in FKRP function. We examined adeno-associated virus (AAV)-mediated LARGE or FKRP overexpression in two dystrophic mouse models with loss-of-function mutations: (1) Large(myd) (LARGE gene) and (2) FKRP(P448L) (FKRP gene). The results agree with previous findings that overexpression of LARGE can ameliorate the dystrophic phenotypes of Large(myd) mice. In addition, LARGE overexpression in the FKRP(P448L) mice effectively generated functional glycosylation (hyperglycosylation) of α-DG and improved dystrophic pathologies in treated muscles. Conversely, FKRP transgene overexpression failed to rescue the defect in glycosylation and improve the phenotypes of the Large(myd) mice. Our findings suggest that AAV-mediated LARGE gene therapy may still be a viable therapeutic strategy for dystroglycanopathies with FKRP deficiency.
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Affiliation(s)
- Charles H Vannoy
- 1 McColl-Lockwood Laboratory for Muscular Dystrophy Research, Cannon Research Center, Carolinas Medical Center , Carolinas Healthcare System, Charlotte, NC 28231
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Clinical, radiological, and genetic survey of patients with muscle-eye-brain disease caused by mutations in POMGNT1. Pediatr Neurol 2014; 50:491-7. [PMID: 24731844 DOI: 10.1016/j.pediatrneurol.2014.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/16/2013] [Accepted: 01/01/2014] [Indexed: 01/15/2023]
Abstract
BACKGROUND To evaluate clinical, genetic, and radiologic features of our patients with muscle-eye-brain disease. METHODS The data of patients who were diagnosed with muscle-eye-brain disease from a cohort of patients with congenital muscular dystrophy in the Division of Pediatric Neurology of Dokuz Eylül University School of Medicine and Gaziantep Children's Hospital between 2005 and 2013 were analyzed retrospectively. RESULTS From a cohort of 34 patients with congenital muscular dystrophy, 12 patients from 10 families were diagnosed with muscle-eye-brain disease. The mean age of the patients was 9 ± 5.5 years (2-19 years). Mean serum creatine kinase value was 2485.80 ± 1308.54 IU/L (700-4267 IU/L). All patients presented with muscular hypotonia at birth followed by varying degrees of spasticity and exaggerated deep tendon reflexes in later stages of life. Three patients were able to walk. The most common ophthalmologic and radiologic abnormalities were cataracts, retinal detachment, periventricular white matter abnormalities, ventriculomegaly, pontocerebellar hypoplasia, and multiple cerebellar cysts. All of the patients had mutations in the POMGNT1 gene. The most common mutation detected in 66% of patients was c.1814 G > A (p.R605H). Two novel mutations were identified. CONCLUSIONS We suggest that muscle-eye-brain disease is a relatively common muscular dystrophy in Turkey. It should be suspected in patients with muscular hypotonia, increased creatine kinase, and structural eye and brain abnormalities. The c.1814 G > A mutation in exon 21 of the POMGNT1 gene is apparently a common mutation in the Turkish population. Individuals with this mutation show classical features of muscle-eye-brain disease, but others may exhibit a milder phenotype and retain the ability to walk independently. Congenital muscular dystrophy patients from Turkey carrying the clinical and radiologic features of muscle-eye-brain disease should be evaluated for mutations in POMGNT1 gene.
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Winterhalter PR, Lommel M, Ruppert T, Strahl S. O-glycosylation of the non-canonical T-cadherin from rabbit skeletal muscle by single mannose residues. FEBS Lett 2013; 587:3715-21. [DOI: 10.1016/j.febslet.2013.09.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 09/16/2013] [Accepted: 09/23/2013] [Indexed: 11/28/2022]
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Sharpe KM, Premsukh MD, Townsend D. Alterations of dystrophin-associated glycoproteins in the heart lacking dystrophin or dystrophin and utrophin. J Muscle Res Cell Motil 2013; 34:395-405. [PMID: 24096570 DOI: 10.1007/s10974-013-9362-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/26/2013] [Indexed: 11/26/2022]
Abstract
Heart disease is a leading cause of death in patients with Duchenne muscular dystrophy (DMD). Patients with DMD lack the protein dystrophin, which is widely expressed in striated muscle. In skeletal muscle, the loss of dystrophin results in dramatically decreased expression of the dystrophin associated glycoprotein complex (DGC). Interestingly, in the heart the DGC is normally expressed without dystrophin; this has been attributed to presence of the dystrophin homologue utrophin. We demonstrate here that neither utrophin nor dystrophin are required for the expression of the cardiac DGC. However, alpha-dystroglycan (α-DG), a major component of the DGC, is differentially glycosylated in dystrophin-(mdx) and dystrophin-/utrophin-(dko) deficient mouse hearts. In both models the altered α-DG retains laminin binding activity, but has an altered localization at the sarcolemma. In hearts lacking both dystrophin and utrophin, the alterations in α-DG glycosylation are even more dramatic with changes in gel migration equivalent to 24 ± 3 kDa. These data show that the absence of dystrophin and utrophin alters the processing of α-DG; however it is not clear if these alterations are a consequence of the loss of a direct interaction with dystrophin/utrophin or results from an indirect response to the presence of severe pathology. Recently there have been great advances in our understanding of the glycosylation of α-DG regarding its role as a laminin receptor. Here we present data that alterations in glycosylation occur in the hearts of animal models of DMD, but these changes do not affect laminin binding. The physiological consequences of these alterations remain unknown, but may have significant implications for the development of therapies for DMD.
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Affiliation(s)
- Katharine M Sharpe
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
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27
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Johnson EK, Li B, Yoon JH, Flanigan KM, Martin PT, Ervasti J, Montanaro F. Identification of new dystroglycan complexes in skeletal muscle. PLoS One 2013; 8:e73224. [PMID: 23951345 PMCID: PMC3738564 DOI: 10.1371/journal.pone.0073224] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/18/2013] [Indexed: 01/16/2023] Open
Abstract
The dystroglycan complex contains the transmembrane protein β-dystroglycan and its interacting extracellular mucin-like protein α-dystroglycan. In skeletal muscle fibers, the dystroglycan complex plays an important structural role by linking the cytoskeletal protein dystrophin to laminin in the extracellular matrix. Mutations that affect any of the proteins involved in this structural axis lead to myofiber degeneration and are associated with muscular dystrophies and congenital myopathies. Because loss of dystrophin in Duchenne muscular dystrophy (DMD) leads to an almost complete loss of dystroglycan complexes at the myofiber membrane, it is generally assumed that the vast majority of dystroglycan complexes within skeletal muscle fibers interact with dystrophin. The residual dystroglycan present in dystrophin-deficient muscle is thought to be preserved by utrophin, a structural homolog of dystrophin that is up-regulated in dystrophic muscles. However, we found that dystroglycan complexes are still present at the myofiber membrane in the absence of both dystrophin and utrophin. Our data show that only a minority of dystroglycan complexes associate with dystrophin in wild type muscle. Furthermore, we provide evidence for at least three separate pools of dystroglycan complexes within myofibers that differ in composition and are differentially affected by loss of dystrophin. Our findings indicate a more complex role of dystroglycan in muscle than currently recognized and may help explain differences in disease pathology and severity among myopathies linked to mutations in DAPC members.
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Affiliation(s)
- Eric K. Johnson
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Ohio State Biochemistry Program, the Ohio State University, Columbus, Ohio, United States of America
| | - Bin Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jung Hae Yoon
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
| | - Kevin M. Flanigan
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Paul T. Martin
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - James Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Federica Montanaro
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Ohio State Biochemistry Program, the Ohio State University, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
- * E-mail:
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28
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Jae LT, Raaben M, Riemersma M, van Beusekom E, Blomen VA, Velds A, Kerkhoven RM, Carette JE, Topaloglu H, Meinecke P, Wessels MW, Lefeber DJ, Whelan SP, van Bokhoven H, Brummelkamp TR. Deciphering the glycosylome of dystroglycanopathies using haploid screens for lassa virus entry. Science 2013; 340:479-83. [PMID: 23519211 DOI: 10.1126/science.1233675] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glycosylated α-dystroglycan (α-DG) serves as cellular entry receptor for multiple pathogens, and defects in its glycosylation cause hereditary Walker-Warburg syndrome (WWS). At least eight proteins are critical to glycosylate α-DG, but many genes mutated in WWS remain unknown. To identify modifiers of α-DG, we performed a haploid screen for Lassa virus entry, a hemorrhagic fever virus causing thousands of deaths annually that hijacks glycosylated α-DG to enter cells. In complementary screens, we profiled cells for absence of α-DG carbohydrate chains or biochemically related glycans. This revealed virus host factors and a suite of glycosylation units, including all known Walker-Warburg genes and five additional factors critical for the modification of α-DG. Our findings accentuate the complexity of this posttranslational feature and point out genes defective in dystroglycanopathies.
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Affiliation(s)
- Lucas T Jae
- Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, Netherlands
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29
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Wells L. The o-mannosylation pathway: glycosyltransferases and proteins implicated in congenital muscular dystrophy. J Biol Chem 2013; 288:6930-5. [PMID: 23329833 DOI: 10.1074/jbc.r112.438978] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Several forms of congenital muscular dystrophy, referred to as dystroglycanopathies, result from defects in the protein O-mannosylation biosynthetic pathway. In this minireview, I discuss 12 proteins involved in the pathway and how they play a role in the building of glycan structures (most notably on the protein α-dystroglycan) that allow for binding to multiple proteins of the extracellular matrix.
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Affiliation(s)
- Lance Wells
- Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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30
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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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31
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Gomez Toledo A, Raducu M, Cruces J, Nilsson J, Halim A, Larson G, Rüetschi U, Grahn A. O-Mannose and O-N-acetyl galactosamine glycosylation of mammalian α-dystroglycan is conserved in a region-specific manner. Glycobiology 2012; 22:1413-23. [PMID: 22781125 DOI: 10.1093/glycob/cws109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Defects in the O-linked glycosylation of the peripheral membrane protein α-dystroglycan (α-DG) are the main cause of several forms of congenital muscular dystrophies and thus the characterization of the glycosylation of α-DG is of great medical importance. A detailed investigation of the glycosylation pattern of the native α-DG protein is essential for the understanding of the biological processes related to human disease in which the protein is involved. To date, several studies have reported novel O-glycans and attachment sites on the mucin-like domain of mammalian α-DG with both similar and contradicting glycosylation patterns, indicating the species-specific O-glycosylation of mammalian α-DG. By applying a standardized purification scheme and subsequent glycoproteomic analysis of native α-DG from rabbit and human skeletal muscle biopsies and from cultured mouse C2C12 myotubes, we show that the O-glycosylation patterns of the mucin-like domain of native α-DG are conserved among mammalians in a region-specific manner.
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Affiliation(s)
- Alejandro Gomez Toledo
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden
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32
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Abstract
Protein glycosylation is a ubiquitous post-translational modification found in all domains of life. Despite their significant complexity in animal systems, glycan structures have crucial biological and physiological roles, from contributions in protein folding and quality control to involvement in a large number of biological recognition events. As a result, they impart an additional level of 'information content' to underlying polypeptide structures. Improvements in analytical methodologies for dissecting glycan structural diversity, along with recent developments in biochemical and genetic approaches for studying glycan biosynthesis and catabolism, have provided a greater understanding of the biological contributions of these complex structures in vertebrates.
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33
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Harrison R, Hitchen PG, Panico M, Morris HR, Mekhaiel D, Pleass RJ, Dell A, Hewitt JE, Haslam SM. Glycoproteomic characterization of recombinant mouse α-dystroglycan. Glycobiology 2012; 22:662-75. [PMID: 22241827 PMCID: PMC3311285 DOI: 10.1093/glycob/cws002] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 01/04/2012] [Accepted: 01/04/2012] [Indexed: 12/15/2022] Open
Abstract
α-Dystroglycan (DG) is a key component of the dystrophin-glycoprotein complex. Aberrant glycosylation of the protein has been linked to various forms of congenital muscular dystrophy. Unusually α-DG has previously been demonstrated to be modified with both O-N-acetylgalactosamine and O-mannose initiated glycans. In the present study, Fc-tagged recombinant mouse α-DG was expressed and purified from human embryonic kidney 293T cells. α-DG glycopeptides were characterized by glycoproteomic strategies using both nano-liquid chromatography matrix-assisted laser desorption ionization and electrospray tandem mass spectrometry. A total of 14 different peptide sequences and 38 glycopeptides were identified which displayed heterogeneous O-glycosylation. These data provide new insights into the complex domain-specific O-glycosylation of α-DG.
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Affiliation(s)
- Rebecca Harrison
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
| | - Paul G Hitchen
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
| | - Maria Panico
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
| | - Howard R Morris
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
| | - David Mekhaiel
- Centre for Genetics and Genomics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Richard J Pleass
- Centre for Genetics and Genomics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Anne Dell
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
| | - Jane E Hewitt
- Centre for Genetics and Genomics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Stuart M Haslam
- Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, UK
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34
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Abstract
A significant proportion of severe, inherited congenital muscular dystrophies are due to aberrant glycosylation of the extracellular matrix receptor α-dystroglycan and a consequent lack of ligand-binding activity. A key member of this glycosylation pathway is the LARGE protein, which was originally identified through genome sequencing and genetic studies. Until recently, the biochemical activity of this enzyme proved frustratingly elusive, but a recent study shows that LARGE encodes a bifunctional glycosyltransferase that synthesizes a novel polysaccharide structure, which is required for functional dystroglycan. Identification of this structure should lead to development of new diagnostic tools and therapeutic strategies for these dystrophies.
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Affiliation(s)
- Jane E Hewitt
- School of Biology, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK
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35
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Kuga A, Kanagawa M, Sudo A, Chan YM, Tajiri M, Manya H, Kikkawa Y, Nomizu M, Kobayashi K, Endo T, Lu QL, Wada Y, Toda T. Absence of post-phosphoryl modification in dystroglycanopathy mouse models and wild-type tissues expressing non-laminin binding form of α-dystroglycan. J Biol Chem 2012; 287:9560-7. [PMID: 22270369 DOI: 10.1074/jbc.m111.271767] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
α-Dystroglycan (α-DG) is a membrane-associated glycoprotein that interacts with several extracellular matrix proteins, including laminin and agrin. Aberrant glycosylation of α-DG disrupts its interaction with ligands and causes a certain type of muscular dystrophy commonly referred to as dystroglycanopathy. It has been reported that a unique O-mannosyl tetrasaccharide (Neu5Ac-α2,3-Gal-β1,4-GlcNAc-β1,2-Man) and a phosphodiester-linked modification on O-mannose play important roles in the laminin binding activity of α-DG. In this study, we use several dystroglycanopathy mouse models to demonstrate that, in addition to fukutin and LARGE, FKRP (fukutin-related protein) is also involved in the post-phosphoryl modification of O-mannose on α-DG. Furthermore, we have found that the glycosylation status of α-DG in lung and testis is minimally affected by defects in fukutin, LARGE, or FKRP. α-DG prepared from wild-type lung- or testis-derived cells lacks the post-phosphoryl moiety and shows little laminin-binding activity. These results show that FKRP is involved in post-phosphoryl modification rather than in O-mannosyl tetrasaccharide synthesis. Our data also demonstrate that post-phosphoryl modification not only plays critical roles in the pathogenesis of dystroglycanopathy but also is a key determinant of α-DG functional expression as a laminin receptor in normal tissues and cells.
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Affiliation(s)
- Atsushi Kuga
- Division of Neurology/Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Japan
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36
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Muscular dystrophies due to glycosylation defects: diagnosis and therapeutic strategies. Curr Opin Neurol 2012; 24:437-42. [PMID: 21825985 DOI: 10.1097/wco.0b013e32834a95e3] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE OF REVIEW Dystroglycanopathies are a common group of diseases characterized by a reduction in α-dystroglycan glycosylation. This review discusses the recent novel discovery of additional dystroglycanopathy variants and progress in dystroglycanopathy animal models. RECENT FINDINGS Several novel glycosyltransferase genes have been found to be responsible for a dystroglycanopathy phenotype, and in addition recessive mutations in DAG1 have been identified for the first time in a primary dystroglycanopathy. Studies in dystroglycanopathy mouse models have clarified some aspects of the structural defects observed in the central nervous system and in the eye, whereas a study in zebrafish implicates unfolded protein response in the pathogenesis of two of the secondary dystroglycanopathies. SUMMARY Improved understanding of the molecular bases of dystroglycanopathies will lead to more precise diagnosis and genetic counseling; therapeutic strategies are being developed and tested in the preclinical models and it is hoped that these observations will pave the way to therapeutic interventions in humans.
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37
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Inamori KI, Yoshida-Moriguchi T, Hara Y, Anderson ME, Yu L, Campbell KP. Dystroglycan function requires xylosyl- and glucuronyltransferase activities of LARGE. Science 2012; 335:93-6. [PMID: 22223806 PMCID: PMC3702376 DOI: 10.1126/science.1214115] [Citation(s) in RCA: 219] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Posttranslational modification of alpha-dystroglycan (α-DG) by the like-acetylglucosaminyltransferase (LARGE) is required for it to function as an extracellular matrix (ECM) receptor. Mutations in the LARGE gene have been identified in congenital muscular dystrophy patients with brain abnormalities. However, the precise function of LARGE remains unclear. Here we found that LARGE could act as a bifunctional glycosyltransferase, with both xylosyltransferase and glucuronyltransferase activities, which produced repeating units of [-3-xylose-α1,3-glucuronic acid-β1-]. This modification allowed α-DG to bind laminin-G domain-containing ECM ligands.
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Affiliation(s)
- Kei-ichiro Inamori
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
| | - Takako Yoshida-Moriguchi
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
| | - Yuji Hara
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
| | - Mary E. Anderson
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
| | - Liping Yu
- Medical Nuclear Magnetic Resonance Facility, University of Iowa Roy J. and Lucille A. Carver College of Medicine, B291 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
| | - Kevin P. Campbell
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, Department of Internal Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242–1101, USA
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38
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Like-acetylglucosaminyltransferase (LARGE)-dependent modification of dystroglycan at Thr-317/319 is required for laminin binding and arenavirus infection. Proc Natl Acad Sci U S A 2011; 108:17426-31. [PMID: 21987822 DOI: 10.1073/pnas.1114836108] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
α-dystroglycan is a highly O-glycosylated extracellular matrix receptor that is required for anchoring of the basement membrane to the cell surface and for the entry of Old World arenaviruses into cells. Like-acetylglucosaminyltransferase (LARGE) is a key molecule that binds to the N-terminal domain of α-dystroglycan and attaches ligand-binding moieties to phosphorylated O-mannose on α-dystroglycan. Here we show that the LARGE modification required for laminin- and virus-binding occurs on specific Thr residues located at the extreme N terminus of the mucin-like domain of α-dystroglycan. Deletion and mutation analyses demonstrate that the ligand-binding activity of α-dystroglycan is conferred primarily by LARGE modification at Thr-317 and -319, within the highly conserved first 18 amino acids of the mucin-like domain. The importance of these paired residues in laminin-binding and clustering activity on myoblasts and in arenavirus cell entry is confirmed by mutational analysis with full-length dystroglycan. We further demonstrate that a sequence of five amino acids, Thr(317)ProThr(319)ProVal, contains phosphorylated O-glycosylation and, when modified by LARGE is sufficient for laminin-binding. Because the N-terminal region adjacent to the paired Thr residues is removed during posttranslational maturation of dystroglycan, our results demonstrate that the ligand-binding activity resides at the extreme N terminus of mature α-dystroglycan and is crucial for α-dystroglycan to coordinate the assembly of extracellular matrix proteins and to bind arenaviruses on the cell surface.
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39
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Stalnaker SH, Aoki K, Lim JM, Porterfield M, Liu M, Satz JS, Buskirk S, Xiong Y, Zhang P, Campbell KP, Hu H, Live D, Tiemeyer M, Wells L. Glycomic analyses of mouse models of congenital muscular dystrophy. J Biol Chem 2011; 286:21180-90. [PMID: 21460210 DOI: 10.1074/jbc.m110.203281] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dystroglycanopathies are a subset of congenital muscular dystrophies wherein α-dystroglycan (α-DG) is hypoglycosylated. α-DG is an extensively O-glycosylated extracellular matrix-binding protein and a key component of the dystrophin-glycoprotein complex. Previous studies have shown α-DG to be post-translationally modified by both O-GalNAc- and O-mannose-initiated glycan structures. Mutations in defined or putative glycosyltransferase genes involved in O-mannosylation are associated with a loss of ligand-binding activity of α-DG and are causal for various forms of congenital muscular dystrophy. In this study, we sought to perform glycomic analysis on brain O-linked glycan structures released from proteins of three different knock-out mouse models associated with O-mannosylation (POMGnT1, LARGE (Myd), and DAG1(-/-)). Using mass spectrometry approaches, we were able to identify nine O-mannose-initiated and 25 O-GalNAc-initiated glycan structures in wild-type littermate control mouse brains. Through our analysis, we were able to confirm that POMGnT1 is essential for the extension of all observed O-mannose glycan structures with β1,2-linked GlcNAc. Loss of LARGE expression in the Myd mouse had no observable effect on the O-mannose-initiated glycan structures characterized here. Interestingly, we also determined that similar amounts of O-mannose-initiated glycan structures are present on brain proteins from α-DG-lacking mice (DAG1) compared with wild-type mice, indicating that there must be additional proteins that are O-mannosylated in the mammalian brain. Our findings illustrate that classical β1,2-elongation and β1,6-GlcNAc branching of O-mannose glycan structures are dependent upon the POMGnT1 enzyme and that O-mannosylation is not limited solely to α-DG in the brain.
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Affiliation(s)
- Stephanie H Stalnaker
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602-4712, USA
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40
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Abstract
During the last 10 years it has become apparent that a significant subset of inherited muscular dystrophy is caused by errors in the glycosylation of α-dystroglycan. Many of these dystrophies are also associated with abnormalities of the central nervous system. Dystroglycan has to be fully glycosylated in order bind to its ligands. To date, six genes have been shown to be essential for functional dystroglycan glycosylation and most, if not all, of these genes act in the formation of O-mannosyl glycans. Genetic heterogeneity indicates that other genes are involved in this pathway. Identification of these additional genes would increase our understanding of this specific and essential glycosylation pathway.
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41
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Stalnaker SH, Hashmi S, Lim JM, Aoki K, Porterfield M, Gutierrez-Sanchez G, Wheeler J, Ervasti JM, Bergmann C, Tiemeyer M, Wells L. Site mapping and characterization of O-glycan structures on alpha-dystroglycan isolated from rabbit skeletal muscle. J Biol Chem 2010; 285:24882-91. [PMID: 20507986 PMCID: PMC2915724 DOI: 10.1074/jbc.m110.126474] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 05/19/2010] [Indexed: 01/11/2023] Open
Abstract
The main extracellular matrix binding component of the dystrophin-glycoprotein complex, alpha-dystroglycan (alpha-DG), which was originally isolated from rabbit skeletal muscle, is an extensively O-glycosylated protein. Previous studies have shown alpha-DG to be modified by both O-GalNAc- and O-mannose-initiated glycan structures. O-Mannosylation, which accounts for up to 30% of the reported O-linked structures in certain tissues, has been rarely observed on mammalian proteins. Mutations in multiple genes encoding defined or putative glycosyltransferases involved in O-mannosylation are causal for various forms of congenital muscular dystrophy. Here, we explore the glycosylation of purified rabbit skeletal muscle alpha-DG in detail. Using tandem mass spectrometry approaches, we identify 4 O-mannose-initiated and 17 O-GalNAc-initiated structures on alpha-DG isolated from rabbit skeletal muscle. Additionally, we demonstrate the use of tandem mass spectrometry-based workflows to directly analyze glycopeptides generated from the purified protein. By combining glycomics and tandem mass spectrometry analysis of 91 glycopeptides from alpha-DG, we were able to assign 21 different residues as being modified by O-glycosylation with differing degrees of microheterogeneity; 9 sites of O-mannosylation and 14 sites of O-GalNAcylation were observed with only two sites definitively exhibiting occupancy by either type of glycan. The distribution of identified sites of O-mannosylation suggests a limited role for local primary sequence in dictating sites of attachment.
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Affiliation(s)
| | - Sana Hashmi
- From the Complex Carbohydrate Research Center and
| | - Jae-Min Lim
- From the Complex Carbohydrate Research Center and
| | | | - Mindy Porterfield
- From the Complex Carbohydrate Research Center and
- Departments of Chemistry and
| | | | | | - James M. Ervasti
- the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Carl Bergmann
- From the Complex Carbohydrate Research Center and
- Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-4712 and
| | - Michael Tiemeyer
- From the Complex Carbohydrate Research Center and
- Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-4712 and
| | - Lance Wells
- From the Complex Carbohydrate Research Center and
- Departments of Chemistry and
- Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-4712 and
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42
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Biological role of dystroglycan in Schwann cell function and its implications in peripheral nervous system diseases. J Biomed Biotechnol 2010; 2010:740403. [PMID: 20625412 PMCID: PMC2896880 DOI: 10.1155/2010/740403] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 04/20/2010] [Indexed: 11/17/2022] Open
Abstract
Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC) that links extracellular matrix with cytoskeleton, expressed in a variety of fetal and adult tissues. Dystroglycan plays diverse roles in development and homeostasis including basement membrane formation, epithelial morphogenesis, membrane stability, cell polarization, and cell migration. In this paper, we will focus on biological role of dystroglycan in Schwann cell function, especially myelination. First, we review the molecular architecture of DGC in Schwann cell abaxonal membrane. Then, we will review the loss-of-function studies using targeted mutagenesis, which have revealed biological functions of each component of DGC in Schwann cells. Based on these findings, roles of dystroglycan in Schwann cell function, in myelination in particular, and its implications in diseases will be discussed in detail. Finally, in view of the fact that understanding the role of dystroglycan in Schwann cells is just beginning, future perspectives will be discussed.
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43
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Nilsson J, Nilsson J, Larson G, Grahn A. Characterization of site-specific O-glycan structures within the mucin-like domain of alpha-dystroglycan from human skeletal muscle. Glycobiology 2010; 20:1160-9. [PMID: 20507882 DOI: 10.1093/glycob/cwq082] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The glycosylation of the extracellular protein alpha-dystroglycan is important for its ligand-binding activity, and altered or blocked glycosylation is associated with several forms of congenital muscular dystrophies. By immunoprecipitation and sialic acid capture-and-release enrichment strategies, we isolated tryptic glycopeptides of alpha-dystroglycan from human skeletal muscle. Nano-liquid chromatography tandem mass spectrometry was used to identify both glycopeptides and peptides corresponding to the mucin-like and C-terminal domain of alpha-dystroglycan. The O-glycans found had either Hex-O-Thr or HexNAc-O-Ser/Thr anchored structures, which were often elongated and frequently, but not always, terminated with sialic acid. The HexNAc-O-Ser/Thr, but not Hex-O-Thr glycopeptides, displayed heterogeneity regarding glycan core structures and level of glycosylation site occupancy. We demonstrate for the first time glycan attachment sites of the NeuAcHexHexNAcHex-O structure corresponding to the anticipated Neu5Acalpha3Galbeta4GlcNAcbeta2Man-O-glycan (sLacNAc-Man), within the mucin-like domain of human alpha-dystroglycan from human skeletal muscle. Twenty-five glycopeptides were characterized from human alpha-dystroglycan, which provide insight to the complex in vivo O-glycosylation of alpha-dystroglycan.
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Affiliation(s)
- Johanna Nilsson
- Institute of Biomedicine, Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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44
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Nakamura N, Lyalin D, Panin VM. Protein O-mannosylation in animal development and physiology: from human disorders to Drosophila phenotypes. Semin Cell Dev Biol 2010; 21:622-30. [PMID: 20362685 DOI: 10.1016/j.semcdb.2010.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/10/2010] [Accepted: 03/25/2010] [Indexed: 12/13/2022]
Abstract
Protein O-mannosylation has a profound effect on the development and physiology of mammalian organisms. Mutations in genes affecting O-mannosyl glycan biosynthesis result in congenital muscular dystrophies. The main pathological mechanism triggered by O-mannosylation defects is a compromised interaction of cells with the extracellular matrix due to abnormal glycosylation of alpha-dystroglycan. Hypoglycosylation of alpha-dystroglycan impairs its ligand-binding activity and results in muscle degeneration and failure of neuronal migration. Recent experiments revealed the existence of compensatory mechanisms that could ameliorate defects of O-mannosylation. However, these mechanisms remain poorly understood. O-mannosylation and dystroglycan pathway genes show remarkable evolutionary conservation in a wide range of metazoans. Mutations and downregulation of these genes in zebrafish and Drosophila result in muscle defects and degeneration, also causing neurological phenotypes, which suggests that O-mannosylation has similar functions in mammals and lower animals. Thus, future studies in genetically tractable model organisms, such as zebrafish and Drosophila, should help to reveal molecular and genetic mechanisms of mammalian O-mannosylation and its role in the regulation of dystroglycan function.
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Affiliation(s)
- Naosuke Nakamura
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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Yoshida-Moriguchi T, Yu L, Stalnaker SH, Davis S, Kunz S, Madson M, Oldstone MBA, Schachter H, Wells L, Campbell KP. O-mannosyl phosphorylation of alpha-dystroglycan is required for laminin binding. Science 2010; 327:88-92. [PMID: 20044576 DOI: 10.1126/science.1180512] [Citation(s) in RCA: 259] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Alpha-dystroglycan (alpha-DG) is a cell-surface glycoprotein that acts as a receptor for both extracellular matrix proteins containing laminin-G domains and certain arenaviruses. Receptor binding is thought to be mediated by a posttranslational modification, and defective binding with laminin underlies a subclass of congenital muscular dystrophy. Using mass spectrometry- and nuclear magnetic resonance (NMR)-based structural analyses, we identified a phosphorylated O-mannosyl glycan on the mucin-like domain of recombinant alpha-DG, which was required for laminin binding. We demonstrated that patients with muscle-eye-brain disease and Fukuyama congenital muscular dystrophy, as well as mice with myodystrophy, commonly have defects in a postphosphoryl modification of this phosphorylated O-linked mannose, and that this modification is mediated by the like-acetylglucosaminyltransferase (LARGE) protein. These findings expand our understanding of the mechanisms that underlie congenital muscular dystrophy.
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Affiliation(s)
- Takako Yoshida-Moriguchi
- Howard Hughes Medical Institute, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, IA 52242-1101, USA
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Suzuki N, Hozumi K, Urushibata S, Yoshimura T, Kikkawa Y, Gumerson JD, Michele DE, Hoffman MP, Yamada Y, Nomizu M. Identification of alpha-dystroglycan binding sequences in the laminin alpha2 chain LG4-5 module. Matrix Biol 2009; 29:143-51. [PMID: 19800000 DOI: 10.1016/j.matbio.2009.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 09/19/2009] [Accepted: 09/21/2009] [Indexed: 12/16/2022]
Abstract
The biological activities of the laminin alpha2 chain LG4-5 module result from interactions with cell surface receptors, such as heparan sulfate proteoglycans and alpha-dystroglycan. In this study, heparin and alpha-dystroglycan binding sequences were identified using 42 overlapping synthetic peptides from the LG4-5 module and using recombinant LG4-5 protein (rec-alpha2LG4-5). Physiological activities of the active peptides were also examined in explants of submandibular glands. Heparin binding screens showed that the A2G78 peptide (GLLFYMARINHA) bound to heparin and prevented its binding to rec-alpha2LG4-5. Furthermore, alanine substitution of the arginine residue in the A2G78 site on rec-alpha2LG4-5 decreased heparin binding activity. When alpha-dystroglycan binding of the peptides was screened, two peptides, A2G78 and A2G80 (VQLRNGFPYFSY), bound alpha-dystroglycan. A2G78 and A2G80 also inhibited alpha-dystroglycan binding of rec-alpha2LG4-5. A2G78 and A2G80 specifically inhibited end bud formation of submandibular glands in culture. These results suggest that the A2G78 and A2G80 sites play functional roles as heparan sulfate- and alpha-dystroglycan-binding sites in the module. These peptides are useful for elucidating molecular mechanisms of heparan sulfate- and/or alpha-dystroglycan-mediated biological functions of the laminin alpha2 chain.
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Affiliation(s)
- Nobuharu Suzuki
- Laboratory of Clinical Biochemistry, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
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Hewitt JE. Abnormal glycosylation of dystroglycan in human genetic disease. Biochim Biophys Acta Mol Basis Dis 2009; 1792:853-61. [DOI: 10.1016/j.bbadis.2009.06.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/05/2009] [Accepted: 06/10/2009] [Indexed: 10/20/2022]
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Aguilan JT, Sundaram S, Nieves E, Stanley P. Mutational and functional analysis of Large in a novel CHO glycosylation mutant. Glycobiology 2009; 19:971-86. [PMID: 19470663 DOI: 10.1093/glycob/cwp074] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Inactivating mutations of Large reduce the functional glycosylation of alpha-dystroglycan (alpha-DG) and lead to muscular dystrophy in mouse and humans. The N-terminal domain of Large is most similar to UDP-glucose glucosyltransferases (UGGT), and the C-terminal domain is related to the human i blood group transferase beta1,3GlcNAcT-1. The amino acids at conserved motifs DQD+1 and DQD+3 in the UGGT domain are necessary for mammalian UGGT activity. When the corresponding residues were mutated to Ala in mouse Large, alpha-DG was not functionally glycosylated. A similar result was obtained when a DXD motif in the beta1,3GlcNAcT-1 domain was mutated to AIA. Therefore, the first putative glycosyltransferase domain of Large has properties of a UGGT and the second of a typical glycosyltransferase. Co-transfection of Large mutants affected in the different glycosyltransferase domains did not lead to complementation. While Large mutants were more localized to the endoplasmic reticulum than wild-type Large or revertants, all mutants were in the Golgi, and only very low levels of Golgi-localized Large were necessary to generate functional alpha-DG. When Large was overexpressed in ldlD.Lec1 mutant Chinese hamster ovary (CHO) cells which synthesize few, if any, mucin O-GalNAc glycans and no complex N-glycans, functional alpha-DG was produced, presumably by modifying O-mannose glycans. To investigate mucin O-GalNAc glycans as substrates of Large, a new CHO mutant Lec15.Lec1 that lacked O-mannose and complex N-glycans was isolated and characterized. Following transfection with Large, Lec15.Lec1 cells also generated functionally glycosylated alpha-DG. Thus, Large may act on the O-mannose, complex N-glycans and mucin O-GalNAc glycans of alpha-DG.
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Affiliation(s)
- Jennifer T Aguilan
- Department of Cell Biology, Albert Einstein College Medicine, New York, NY 10461, USA
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Abstract
In the last few years, muscular dystrophies due to reduced glycosylation of alpha-dystroglycan (ADG) have emerged as a common group of conditions, now referred to as dystroglycanopathies. Mutations in six genes (POMT1, POMT2, POMGnT1, Fukutin, FKRP and LARGE) have so far been identified in patients with a dystroglycanopathy. Allelic mutations in each of these genes can result in a wide spectrum of clinical conditions, ranging from severe congenital onset with associated structural brain malformations (Walker Warburg syndrome; muscle-eye-brain disease; Fukuyama muscular dystrophy; congenital muscular dystrophy type 1D) to a relatively milder congenital variant with no brain involvement (congenital muscular dystrophy type 1C), and to limb-girdle muscular dystrophy (LGMD) type 2 variants with onset in childhood or adult life (LGMD2I, LGMD2L, and LGMD2N). ADG is a peripheral membrane protein that undergoes multiple and complex glycosylation steps to regulate its ability to effectively interact with extracellular matrix proteins, such as laminin, agrin, and perlecan. Although the precise composition of the glycans present on ADG are not known, it has been demonstrated that the forced overexpression of LARGE, or its paralog LARGE2, is capable of increasing the glycosylation of ADG in normal cells. In addition, its overexpression is capable of restoring dystroglycan glycosylation and laminin binding properties in primary cell cultures of patients affected by different genetically defined dystroglycanopathy variants. These observations suggest that there could be a role for therapeutic strategies to overcome the glycosylation defect in these conditions via the overexpression of LARGE.
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Affiliation(s)
- Francesco Muntoni
- Department of Neuroscience, Dubowitz Neuromuscular Centre, UCL Institute of Child Health & Great Ormond Street Hospital, London, United Kingdom.
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Moore CJ, Hewitt JE. Dystroglycan glycosylation and muscular dystrophy. Glycoconj J 2008; 26:349-57. [PMID: 18773291 DOI: 10.1007/s10719-008-9182-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 08/14/2008] [Accepted: 08/18/2008] [Indexed: 11/25/2022]
Abstract
Dystroglycan is an integral member of the skeletal muscle dystrophin glycoprotein complex, which links dystrophin to proteins in the extracellular matrix. Recently, a group of human muscular dystrophy disorders have been demonstrated to result from defective glycosylation of the alpha-dystroglycan subunit. Genetic studies of these diseases have identified six genes that encode proteins required for the synthesis of essential carbohydrate structures on dystroglycan. Here we highlight their known or postulated functions. This glycosylation pathway appears to be highly specific (dystroglycan is the only substrate identified thus far) and to be highly conserved during evolution.
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Affiliation(s)
- Christopher J Moore
- Institute of Genetics, School of Biology, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
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