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Younger DS. Childhood muscular dystrophies. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:461-496. [PMID: 37562882 DOI: 10.1016/b978-0-323-98818-6.00024-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Infancy- and childhood-onset muscular dystrophies are associated with a characteristic distribution and progression of motor dysfunction. The underlying causes of progressive childhood muscular dystrophies are heterogeneous involving diverse genetic pathways and genes that encode proteins of the plasma membrane, extracellular matrix, sarcomere, and nuclear membrane components. The prototypical clinicopathological features in an affected child may be adequate to fully distinguish it from other likely diagnoses based on four common features: (1) weakness and wasting of pelvic-femoral and scapular muscles with involvement of heart muscle; (2) elevation of serum muscle enzymes in particular serum creatine kinase; (3) necrosis and regeneration of myofibers; and (4) molecular neurogenetic assessment particularly utilizing next-generation sequencing of the genome of the likeliest candidates genes in an index case or family proband. A number of different animal models of therapeutic strategies have been developed for gene transfer therapy, but so far these techniques have not yet entered clinical practice. Treatment remains for the most part symptomatic with the goal of ameliorating locomotor and cardiorespiratory manifestations of the disease.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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2
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Uribe ML, Martín-Nieto J, Quereda C, Rubio-Fernández M, Cruces J, Janssen GMC, de Ru AH, van Veelen PA, Hensbergen PJ. Retinal Proteomics of a Mouse Model of Dystroglycanopathies Reveals Molecular Alterations in Photoreceptors. J Proteome Res 2021; 20:3268-3277. [PMID: 34027671 PMCID: PMC8280732 DOI: 10.1021/acs.jproteome.1c00126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Mutations in the POMT1 gene, encoding a protein O-mannosyltransferase
essential for α-dystroglycan
(α-DG) glycosylation, are frequently observed in a group of
rare congenital muscular dystrophies, collectively known as dystroglycanopathies.
However, it is hitherto unclear whether the effects seen in affected
patients can be fully ascribed to α-DG hypoglycosylation. To
study this, here we used comparative mass spectrometry-based proteomics
and immunofluorescence microscopy and investigated the changes in
the retina of mice in which Pomt1 is specifically
knocked out in photoreceptor cells. Our results demonstrate significant
proteomic changes and associated structural alteration in photoreceptor
cells of Pomt1 cKO mice. In addition to the effects
related to impaired α-DG O-mannosylation, we
observed morphological alterations in the outer segment that are associated
with dysregulation of a relatively understudied POMT1 substrate (KIAA1549),
BBSome proteins, and retinal stress markers. In conclusion, our study
provides new hypotheses to explain the phenotypic changes that are
observed in the retina of patients with dystroglycanopathies.
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Affiliation(s)
- Mary Luz Uribe
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - José Martín-Nieto
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain.,Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Cristina Quereda
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - Marcos Rubio-Fernández
- Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Universidad Autónoma de Madrid, 28029 Madrid, Spain
| | - George M C Janssen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Arnoud H de Ru
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Peter A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
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3
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El-Dessouky SH, Hosny H, Elarab AE, Issa MY. Prenatal presentation of Walker–Warburg syndrome with a POMT2 mutation: an extended fetal phenotype. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2020. [DOI: 10.1186/s43042-020-00093-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Walker–Warburg syndrome (WWS) is a rare, lethal, genetically, and clinically heterogeneous congenital muscular dystrophy resulting from defective glycosylation of α-dystroglycan (α-DG) and is associated with both cranial and ocular malformations. Prenatal detection of posterior fossa anomalies in association with hydrocephalus are nonspecific, however, an additional finding of eye anomalies are typical for WWS. The purpose of this report is to elucidate the pattern of associated malformations in a fetus with WWS born to 3rd degree consanguineously married couple. Additionally, the fetal ultrasonography revealed congenital heart disease, clenched hands, and talipes equinovarus; these findings have not been previously reported and represent an expansion of prenatal spectrum associated with WWS.
Case presentation
We report on a specific sonographic pattern of congenital anomalies including hydrocephalus, agenesis of corpus callosum, and Dandy–Walker malformation. Ocular abnormalities include microphthalmia, cataract, and an echoic structure suggestive of persistent primary vitreous. Other features include congenital heart disease, unilateral multicystic kidney, and previously unreported findings of bilateral clenched hands and talipes equinovarus. The molecular analysis detected a homozygous splicing mutation, c.924-2A>C, in the POMT2 gene; this variant segregated with the phenotype.
Conclusion
WWS syndrome has characteristic prenatal ultrasound findings which can improve the prenatal identification of this condition and help in guiding the molecular diagnosis and counseling. The detection of bilateral clenched hands and talipes equinovarus is a novel finding that further expands the phenotypic spectrum of WWS.
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4
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Alhamidi M, Brox V, Stensland E, Liset M, Lindal S, Nilssen Ø. Limb girdle muscular dystrophy type 2I: No correlation between clinical severity, histopathology and glycosylated α-dystroglycan levels in patients homozygous for common FKRP mutation. Neuromuscul Disord 2017; 27:619-626. [PMID: 28479227 DOI: 10.1016/j.nmd.2017.02.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 02/05/2017] [Accepted: 02/24/2017] [Indexed: 11/19/2022]
Abstract
Limb girdle muscular dystrophy type 2I (LGMD2I) is a progressive disorder caused by mutations in the FuKutin-Related Protein gene (FKRP). LGMD2I displays clinical heterogeneity with onset of severe symptoms in early childhood to mild calf and thigh hypertrophy in the second or third decade. Patients homozygous for the common FKRP mutation c.826C>A (p.Leu276Ile) show phenotypes within the milder end of the clinical spectrum. However, this group also manifests substantial clinical variability. FKRP deficiency causes hypoglycosylation of α-dystroglycan; a component of the dystrophin associated glycoprotein complex. α-Dystroglycan hypoglycosylation is associated with loss of interaction with laminin α2, which in turn results in laminin α2 depletion. Here, we have attempted to clarify if the clinical variability seen in patients homozygous for c.826C>A is related to alterations in muscle fibre pathology, α-DG glycosylation levels, levels of laminin α2 as well as the capacity of α-DG to bind to laminin. We have assessed vastus lateralis muscle biopsies from 25 LGMD2I patients harbouring the c.826C>A/c.826C>A genotype by histological examination, immunohistochemistry and immunoblotting. No clear correlation was found between clinical severity, as determined by self-reported walking function, and the above features, suggesting that more complex molecular processes are contributing to the progression of disease.
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Affiliation(s)
- Maisoon Alhamidi
- Department of Clinical Medicine, University of Tromsø, NO-9037 Tromsø, Norway; Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North-Norway, NO-9038 Tromsø, Norway
| | - Vigdis Brox
- Department of Clinical Medicine, University of Tromsø, NO-9037 Tromsø, Norway; Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North-Norway, NO-9038 Tromsø, Norway
| | - Eva Stensland
- Department of Clinical Medicine, University of Tromsø, NO-9037 Tromsø, Norway; Department of Habilitation, University Hospital North Norway, NO-9038 Tromsø, Norway
| | - Merete Liset
- Department of Pathology, University Hospital of North-Norway, NO-9038 Tromsø, Norway
| | - Sigurd Lindal
- Department of Pathology, University Hospital of North-Norway, NO-9038 Tromsø, Norway; Institute of Medical Biology, University of Tromsø, NO-9037 Tromsø, Norway
| | - Øivind Nilssen
- Department of Clinical Medicine, University of Tromsø, NO-9037 Tromsø, Norway; Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North-Norway, NO-9038 Tromsø, Norway.
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5
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Abstract
Skeletal muscle performs an essential function in human physiology with defects in genes encoding a variety of cellular components resulting in various types of inherited muscle disorders. Muscular dystrophies (MDs) are a severe and heterogeneous type of human muscle disease, manifested by progressive muscle wasting and degeneration. The disease pathogenesis and therapeutic options for MDs have been investigated for decades using rodent models, and considerable knowledge has been accumulated on the cause and pathogenetic mechanisms of this group of human disorders. However, due to some differences between disease severity and progression, what is learned in mammalian models does not always transfer to humans, prompting the desire for additional and alternative models. More recently, zebrafish have emerged as a novel and robust animal model for the study of human muscle disease. Zebrafish MD models possess a number of distinct advantages for modeling human muscle disorders, including the availability and ease of generating mutations in homologous disease-causing genes, the ability to image living muscle tissue in an intact animal, and the suitability of zebrafish larvae for large-scale chemical screens. In this chapter, we review the current understanding of molecular and cellular mechanisms involved in MDs, the process of myogenesis in zebrafish, and the structural and functional characteristics of zebrafish larval muscles. We further discuss the insights gained from the key zebrafish MD models that have been so far generated, and we summarize the attempts that have been made to screen for small molecules inhibitors of the dystrophic phenotypes using these models. Overall, these studies demonstrate that zebrafish is a useful in vivo system for modeling aspects of human skeletal muscle disorders. Studies using these models have contributed both to the understanding of the pathogenesis of muscle wasting disorders and demonstrated their utility as highly relevant models to implement therapeutic screening regimens.
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Affiliation(s)
- M Li
- Monash University, Clayton, VIC, Australia
| | - K J Hromowyk
- The Ohio State University, Columbus, OH, United States
| | - S L Amacher
- The Ohio State University, Columbus, OH, United States
| | - P D Currie
- Monash University, Clayton, VIC, Australia
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6
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Boldrin L, Zammit PS, Morgan JE. Satellite cells from dystrophic muscle retain regenerative capacity. Stem Cell Res 2014; 14:20-9. [PMID: 25460248 PMCID: PMC4305370 DOI: 10.1016/j.scr.2014.10.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 10/10/2014] [Accepted: 10/23/2014] [Indexed: 12/17/2022] Open
Abstract
Duchenne muscular dystrophy is an inherited disorder that is characterized by progressive skeletal muscle weakness and wasting, with a failure of muscle maintenance/repair mediated by satellite cells (muscle stem cells). The function of skeletal muscle stem cells resident in dystrophic muscle may be perturbed by being in an increasing pathogenic environment, coupled with constant demands for repairing muscle. To investigate the contribution of satellite cell exhaustion to this process, we tested the functionality of satellite cells isolated from the mdx mouse model of Duchenne muscular dystrophy. We found that satellite cells derived from young mdx mice contributed efficiently to muscle regeneration within our in vivo mouse model. To then test the effects of long-term residence in a dystrophic environment, satellite cells were isolated from aged mdx muscle. Surprisingly, they were as functional as those derived from young or aged wild type donors. Removing satellite cells from a dystrophic milieu reveals that their regenerative capacity remains both intact and similar to satellite cells derived from healthy muscle, indicating that the host environment is critical for controlling satellite cell function. Grafted mdx satellite cells regenerate muscle as well as wild-type satellite cells. Aged mdx myofibers bear more satellite cells than aged wild type fibers. mdx satellite cells retain their ability to activate. Aged mdx satellite cells are robustly regenerative in vivo.
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MESH Headings
- Aging
- Animals
- Cells, Cultured
- Disease Models, Animal
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Mice, Nude
- Muscles/pathology
- Muscles/physiology
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Muscular Dystrophy, Duchenne/therapy
- Regeneration
- Satellite Cells, Skeletal Muscle/cytology
- Satellite Cells, Skeletal Muscle/metabolism
- Satellite Cells, Skeletal Muscle/transplantation
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Affiliation(s)
- Luisa Boldrin
- University College London, Institute of Child Health, The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, 30 Guilford Street, London WC1N 1EH, United Kingdom.
| | - Peter S Zammit
- King's College London, The Randall Division of Cell and Molecular Biophysics, New Hunt's House, London SE1 1UL, United Kingdom
| | - Jennifer E Morgan
- University College London, Institute of Child Health, The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, 30 Guilford Street, London WC1N 1EH, United Kingdom.
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7
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Chong YK, Ma LCK, Lo KL, Lee CKL, Mak CM, Kan ANC, Lam CW. Dystroglycanopathy with two novel POMT1 mutations in a Chinese boy with developmental delay and muscular dystrophy. Eur J Paediatr Neurol 2014; 18:532-5. [PMID: 24657014 DOI: 10.1016/j.ejpn.2014.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/28/2014] [Accepted: 03/01/2014] [Indexed: 11/19/2022]
Abstract
Alpha-dystroglycanopathies are a group of diseases due to reduced glycosylation of alpha-dystroglycan, which commonly result from mutations in POMT1, POMT2, and POMGnT1. Patients with alpha-dystroglycanopathies present with muscular, cerebral, and ocular involvements with differing severities. We reported a boy who presented with muscular dystrophy, developmental delay, and non-specific white matter lesions. Mutation analysis of POMT1 was performed and revealed two novel mutations, a substitution mutation (c.176T>G) and a duplication mutation (c.2059dupC) which results in premature termination of translation. In-silico prediction in five different platforms concurred that the substitution is damaging, and functional studies by immunofluorescence revealed lack of staining in the carbohydrate moiety of alpha-dystroglycan, confirming the molecular findings in a functional manner. In conclusion, we reported the first case of genetically confirmed alpha-dystroglycanopathy due to mutations in POMT1 in Chinese.
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Affiliation(s)
- Yeow Kuan Chong
- Genetic Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Louis Che Kwan Ma
- Department of Paediatrics, United Christian Hospital, Hong Kong Special Administrative Region
| | - Kit Lin Lo
- Department of Diagnostic Radiology and Organ Imaging, United Christian Hospital, Hong Kong Special Administrative Region
| | - Clary Ka Lai Lee
- Department of Pathology, United Christian Hospital, Hong Kong Special Administrative Region
| | - Chloe Miu Mak
- Genetic Pathology Laboratory, Department of Pathology, Princess Margaret Hospital, Hong Kong Special Administrative Region
| | - Amanda Nim Chi Kan
- Department of Pathology, Queen Mary Hospital, Hong Kong Special Administrative Region
| | - Ching Wan Lam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region.
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8
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Clinical, pathologic, and mutational spectrum of dystroglycanopathy caused by LARGE mutations. J Neuropathol Exp Neurol 2014; 73:425-41. [PMID: 24709677 DOI: 10.1097/nen.0000000000000065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Dystroglycanopathies are a subtype of congenital muscular dystrophy of varying severity that can affect the brain and eyes, ranging from Walker-Warburg syndrome with severe brain malformation to milder congenital muscular dystrophy presentations with affected or normal cognition and later onset. Mutations in dystroglycanopathy genes affect a specific glycoepitope on α-dystroglycan; of the 14 genes implicated to date, LARGE encodes the glycosyltransferase that adds the final xylose and glucuronic acid, allowing α-dystroglycan to bind ligands, including laminin 211 and neurexin. Only 11 patients with LARGE mutations have been reported. We report the clinical, neuroimaging, and genetic features of 4 additional patients. We confirm that gross deletions and rearrangements are important mutational mechanisms for LARGE. The brain abnormalities overshadowed the initially mild muscle phenotype in all 4 patients. We present the first comprehensive postnatal neuropathology of the brain, spinal cord, and eyes of a patient with a homozygous LARGE mutation at Cys443. In this patient, polymicrogyria was the predominant cortical malformation; densely festooned polymicrogyria were overlaid by a continuous agyric surface. In view of the severity of these abnormalities, Cys443 may be a functionally important residue in the LARGE protein, whereas the mutation p.Glu509Lys of Patient 1 in this study may confer a milder phenotype. Overall, these results expand the clinical and genetic spectrum of dystroglycanopathy.
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9
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Pereira NA, Pu HX, Goh H, Song Z. Golgi phosphoprotein 3 mediates the Golgi localization and function of protein O-linked mannose β-1,2-N-acetlyglucosaminyltransferase 1. J Biol Chem 2014; 289:14762-70. [PMID: 24733390 DOI: 10.1074/jbc.m114.548305] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
GOLPH3 is a highly conserved protein found across the eukaryotic lineage. The yeast homolog, Vps74p, interacts with and maintains the Golgi localization of several mannosyltransferases, which is subsequently critical for N- and O-glycosylation in yeast. Through the use of a T7 phage display, we discovered a novel interaction between GOLPH3 and a mammalian glycosyltransferase, POMGnT1, which is involved in the O-mannosylation of α-dystroglycan. The cytoplasmic tail of POMGnT1 was found to be critical for mediating its interaction with GOLPH3. Loss of this interaction resulted in the inability of POMGnT1 to localize to the Golgi and reduced the functional glycosylation of α-dystroglycan. In addition, we showed that three clinically relevant mutations present in the stem domain of POMGnT1 mislocalized to the endoplasmic reticulum, highlighting the importance of identifying the molecular mechanisms responsible for Golgi localization of glycosyltransferases. Our findings reveal a novel role for GOLPH3 in mediating the Golgi localization of POMGnT1.
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Affiliation(s)
- Natasha A Pereira
- From the Bioprocessing Technology Institute, Agency for Science, Technology, and Research (A*STAR), 20 Biopolis Way, 06-01 Centros, 138668, Singapore
| | - Helen X Pu
- From the Bioprocessing Technology Institute, Agency for Science, Technology, and Research (A*STAR), 20 Biopolis Way, 06-01 Centros, 138668, Singapore
| | - Hazel Goh
- From the Bioprocessing Technology Institute, Agency for Science, Technology, and Research (A*STAR), 20 Biopolis Way, 06-01 Centros, 138668, Singapore
| | - Zhiwei Song
- From the Bioprocessing Technology Institute, Agency for Science, Technology, and Research (A*STAR), 20 Biopolis Way, 06-01 Centros, 138668, Singapore
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10
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Gumerson JD, Davis CS, Kabaeva ZT, Hayes JM, Brooks SV, Michele DE. Muscle-specific expression of LARGE restores neuromuscular transmission deficits in dystrophic LARGE(myd) mice. Hum Mol Genet 2012; 22:757-68. [PMID: 23222475 DOI: 10.1093/hmg/dds483] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in several glycosyltransferases underlie a group of muscular dystrophies known as glycosylation-deficient muscular dystrophy. A common feature of these diseases is loss of glycosylation and consequent dystroglycan function that is correlated with severe pathology in muscle, brain and other tissues. Although glycosylation of dystroglycan is essential for function in skeletal muscle, whether glycosylation-dependent function of dystroglycan is sufficient to explain all complex pathological features associated with these diseases is less clear. Dystroglycan glycosylation is defective in LARGE(myd) (myd) mice as a result of a mutation in like-acetylglucosaminyltransferase (LARGE), a glycosyltransferase known to cause muscle disease in humans. We generated animals with restored dystroglycan function exclusively in skeletal muscle by crossing myd animals to a recently created transgenic line that expresses LARGE selectively in differentiated muscle. Transgenic myd mice were indistinguishable from wild-type littermates and demonstrated an amelioration of muscle disease as evidenced by an absence of muscle pathology, restored contractile function and a reduction in serum creatine kinase activity. Moreover, although deficits in nerve conduction and neuromuscular transmission were observed in myd animals, these deficits were fully rescued by muscle-specific expression of LARGE, which resulted in restored structure of the neuromuscular junction (NMJ). These data demonstrate that, in addition to muscle degeneration and dystrophy, impaired neuromuscular transmission contributes to muscle weakness in dystrophic myd mice and that the noted defects are primarily due to the effects of LARGE and glycosylated dystroglycan in stabilizing the endplate of the NMJ.
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Affiliation(s)
- Jessica D Gumerson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
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11
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Diseases of glycosylation beyond classical congenital disorders of glycosylation. Biochim Biophys Acta Gen Subj 2012; 1820:1306-17. [DOI: 10.1016/j.bbagen.2012.02.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 12/30/2022]
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12
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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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13
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Dystroglycan and dystroglycanopathies: report of the 187th ENMC Workshop 11-13 November 2011, Naarden, The Netherlands. Neuromuscul Disord 2012; 22:659-68. [PMID: 22437172 PMCID: PMC3387367 DOI: 10.1016/j.nmd.2012.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 02/15/2012] [Accepted: 02/16/2012] [Indexed: 11/24/2022]
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14
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Onofre-Oliveira PCG, Santos ALF, Martins PM, Ayub-Guerrieri D, Vainzof M. Differential expression of genes involved in the degeneration and regeneration pathways in mouse models for muscular dystrophies. Neuromolecular Med 2012; 14:74-83. [PMID: 22362587 DOI: 10.1007/s12017-012-8172-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 02/04/2012] [Indexed: 10/28/2022]
Abstract
The genetically determined muscular dystrophies are caused by mutations in genes coding for muscle proteins. Differences in the phenotypes are mainly the age of onset and velocity of progression. Muscle weakness is the consequence of myofiber degeneration due to an imbalance between successive cycles of degeneration/regeneration. While muscle fibers are lost, a replacement of the degraded muscle fibers by adipose and connective tissues occurs. Major investigation points are to elicit the involved pathophysiological mechanisms to elucidate how each mutation can lead to a specific degenerative process and how the regeneration is stimulated in each case. To answer these questions, we used four mouse models with different mutations causing muscular dystrophies, Dmd (mdx), SJL/J, Large (myd) and Lama2 (dy2J) /J, and compared the histological changes of regeneration and fibrosis to the expression of genes involved in those processes. For regeneration, the MyoD, Myf5 and myogenin genes related to the proliferation and differentiation of satellite cells were studied, while for degeneration, the TGF-β1 and Pro-collagen 1α2 genes, involved in the fibrotic cascade, were analyzed. The result suggests that TGF-β1 gene is activated in the dystrophic process in all the stages of degeneration, while the activation of the expression of the pro-collagen gene possibly occurs in mildest stages of this process. We also observed that each pathophysiological mechanism acted differently in the activation of regeneration, with distinctions in the induction of proliferation of satellite cells, but with no alterations in stimulation to differentiation. Dysfunction of satellite cells can, therefore, be an important additional mechanism of pathogenesis in the dystrophic muscle.
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Affiliation(s)
- P C G Onofre-Oliveira
- Human Research Genome Center, Bioscience Institute, University of São Paulo, R. do Matão, travessa 13, no. 106, São Paulo, SP CEP 05508-090, Brazil
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15
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Abstract
Glycosylation is an essential process by which sugars are attached to proteins and lipids. Complete lack of glycosylation is not compatible with life. Because of the widespread function of glycosylation, inherited disorders of glycosylation are multisystemic. Since the identification of the first defect on N-linked glycosylation in the 1980s, there are over 40 different congenital protein hypoglycosylation diseases. This review will include defects of N-linked glycosylation, O-linked glycosylation and disorders of combined N- and O-linked glycosylation.
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Affiliation(s)
- Susan E Sparks
- Department of Pediatrics, Levine Children's Hospital at Carolinas Medical Center, Charlotte, NC, USA; Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
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Identification of cell surface molecules involved in dystroglycan-independent Lassa virus cell entry. J Virol 2011; 86:2067-78. [PMID: 22156524 DOI: 10.1128/jvi.06451-11] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although O-mannosylated dystroglycan is a receptor for Lassa virus, a causative agent of Lassa fever, recent findings suggest the existence of an alternative receptor(s). Here we identified four molecules as receptors for Lassa virus: Axl and Tyro3, from the TAM family, and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and liver and lymph node sinusoidal endothelial calcium-dependent lectin (LSECtin), from the C-type lectin family. These molecules enhanced the binding of Lassa virus to cells and mediated infection independently of dystroglycan. Axl- or Tyro3-mediated infection required intracellular signaling via the tyrosine kinase activity of Axl or Tyro3, whereas DC-SIGN- or LSECtin-mediated infection and binding were dependent on a specific carbohydrate and on ions. The identification of these four molecules as Lassa virus receptors advances our understanding of Lassa virus cell entry.
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Berti C, Bartesaghi L, Ghidinelli M, Zambroni D, Figlia G, Chen ZL, Quattrini A, Wrabetz L, Feltri ML. Non-redundant function of dystroglycan and β1 integrins in radial sorting of axons. Development 2011; 138:4025-37. [PMID: 21862561 DOI: 10.1242/dev.065490] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Radial sorting allows the segregation of axons by a single Schwann cell (SC) and is a prerequisite for myelination during peripheral nerve development. Radial sorting is impaired in models of human diseases, congenital muscular dystrophy (MDC) 1A, MDC1D and Fukuyama, owing to loss-of-function mutations in the genes coding for laminin α2, Large or fukutin glycosyltransferases, respectively. It is not clear which receptor(s) are activated by laminin 211, or glycosylated by Large and fukutin during sorting. Candidates are αβ1 integrins, because their absence phenocopies laminin and glycosyltransferase deficiency, but the topography of the phenotypes is different and β1 integrins are not substrates for Large and fukutin. By contrast, deletion of the Large and fukutin substrate dystroglycan does not result in radial sorting defects. Here, we show that absence of dystroglycan in a specific genetic background causes sorting defects with topography identical to that of laminin 211 mutants, and recapitulating the MDC1A, MDC1D and Fukuyama phenotypes. By epistasis studies in mice lacking one or both receptors in SCs, we show that only absence of β1 integrins impairs proliferation and survival, and arrests radial sorting at early stages, that β1 integrins and dystroglycan activate different pathways, and that the absence of both molecules is synergistic. Thus, the function of dystroglycan and β1 integrins is not redundant, but is sequential. These data identify dystroglycan as a functional laminin 211 receptor during axonal sorting and the key substrate relevant to the pathogenesis of glycosyltransferase congenital muscular dystrophies.
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Affiliation(s)
- Caterina Berti
- Divisions of Genetics and Cell Biology, San Raffaele Scientific Institute, 20132 Milano, Italy
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Chan YM, Brown SC, Lu Q. Second International Workshop for Glycosylation Defects in Muscular Dystrophies, 11-12 November, 2010, Charlotte, USA. Brain Pathol 2011; 21:699-704. [DOI: 10.1111/j.1750-3639.2011.00494.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Abstract
Mutations in fukutin-related protein (FKRP) are responsible for a common group of muscular dystrophies ranging from adult onset limb girdle muscular dystrophies to severe congenital forms with associated structural brain involvement. The defining feature of this group of disorders is the hypoglycosylation of α-dystroglycan and its inability to effectively bind extracellular matrix ligands such as laminin α2. However, α-dystroglycan has the potential to interact with a number of laminin isoforms many of which are basement membrane/tissue specific and developmentally regulated. To further investigate this we evaluated laminin α-chain expression in the cerebral cortex and eye of our FKRP knock-down mouse (FKRP(KD)). These mice showed a marked disturbance in the deposition of laminin α-chains including α1, α2, α4, and α5, although only laminin α1- and γ1-chain mRNA expression was significantly upregulated relative to controls. Moreover, there was a diffuse pattern of laminin deposition below the pial surface which correlated with an abrupt termination of many of the radial glial cells. This along with the pial basement membrane defects, contributed to the abnormal positioning of both early- and late-born neurons. Defects in the inner limiting membrane of the eye were associated with a reduction of laminin α1 demonstrating the involvement of the α-dystroglycan:laminin α1 axis in the disease process. These observations demonstrate for the first time that a reduction in Fkrp influences the ability of tissue-specific forms of α-dystroglycan to direct the deposition of several laminin isoforms in the formation of different basement membranes.
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Stalnaker SH, Stuart R, Wells L. Mammalian O-mannosylation: unsolved questions of structure/function. Curr Opin Struct Biol 2011; 21:603-9. [PMID: 21945038 DOI: 10.1016/j.sbi.2011.09.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/29/2022]
Abstract
Post-translational modification of polypeptides with glycans increases the diversity of the structures of proteins and imparts increased functional diversity. Here, we review the current literature on a relatively new O-glycosylation pathway, the mammalian O-mannosylation pathway. The importance of O-mannosylation is illustrated by the fact that O-mannose glycan structures play roles in a variety of processes including viral entry into cells, metastasis, cell adhesion, and neuronal development. Furthermore, mutations in the enzymes of this pathway are causal for a variety of congenital muscular dystrophies. Here we highlight the protein substrates, glycan structures, and enzymes involved in O-mannosylation as well as our gaps in understanding structure/function relationships in this biosynthetic pathway.
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Affiliation(s)
- Stephanie H Stalnaker
- University of Georgia, Complex Carbohydrate Research Center, Athens, GA, United States
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21
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Aguggia M, Cavallini M, Divito N, Ferrero M, Lentini A, Montano V, Tinebra MC, Saracco MG, Valfrè W. Sleep and primary headaches. Neurol Sci 2011; 32 Suppl 1:S51-4. [DOI: 10.1007/s10072-011-0524-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Abstract
This review presents an overview of human cortical malformation based on the insights gained from examination of human fetal brains. Examination at early stages of fetal brain development allows the identification of the specific pathways which are disrupted in human cortical malformation. Detailed examination of human fetal brains in parallel with studies of genetics and animal models is leading to new concepts of cortical malformations. Here we review a range of human cortical malformations based on a simple classification according to the developmental process thought to be disrupted: neuroblast proliferation, undermigration, overmigration, cortical maturation and destructive lesions. A single case example of a dated intrauterine injury illustrates the spectrum of malformations which may result at a single period in development. The recommended methods of examination of human fetal brain are described together with some of their pitfalls. Detailed neuropathological observations indicate the need for caution in the classification of malformations; radiological findings and pathology of the mature brain do not reflect the specific disruptive pathways of cortical malformations. While many insults may lead to the same pattern of malformation, a single insult can lead to multiple patterns of malformation. Our detailed studies of the human fetal brain suggest that the interface between the meninges and the radial glial end feet may be an intriguing new focus of interest in understanding cortical development.
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Affiliation(s)
- Waney Squier
- Department Neuropathology, John Radcliffe Hospital, Oxford, UK.
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23
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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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Brockington M, Torelli S, Sharp PS, Liu K, Cirak S, Brown SC, Wells DJ, Muntoni F. Transgenic overexpression of LARGE induces α-dystroglycan hyperglycosylation in skeletal and cardiac muscle. PLoS One 2010; 5:e14434. [PMID: 21203384 PMCID: PMC3010994 DOI: 10.1371/journal.pone.0014434] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 12/01/2010] [Indexed: 01/11/2023] Open
Abstract
Background LARGE is one of seven putative or demonstrated glycosyltransferase enzymes defective in a common group of muscular dystrophies with reduced glycosylation of α-dystroglycan. Overexpression of LARGE induces hyperglycosylation of α-dystroglycan in both wild type and in cells from dystroglycanopathy patients, irrespective of their primary gene defect, restoring functional glycosylation. Viral delivery of LARGE to skeletal muscle in animal models of dystroglycanopathy has identical effects in vivo, suggesting that the restoration of functional glycosylation could have therapeutic applications in these disorders. Pharmacological strategies to upregulate Large expression are also being explored. Methodology/Principal Findings In order to asses the safety and efficacy of long term LARGE over-expression in vivo, we have generated four mouse lines expressing a human LARGE transgene. On observation, LARGE transgenic mice were indistinguishable from the wild type littermates. Tissue analysis from young mice of all four lines showed a variable pattern of transgene expression: highest in skeletal and cardiac muscles, and lower in brain, kidney and liver. Transgene expression in striated muscles correlated with α-dystroglycan hyperglycosylation, as determined by immunoreactivity to antibody IIH6 and increased laminin binding on an overlay assay. Other components of the dystroglycan complex and extracellular matrix ligands were normally expressed, and general muscle histology was indistinguishable from wild type controls. Further detailed muscle physiological analysis demonstrated a loss of force in response to eccentric exercise in the older, but not in the younger mice, suggesting this deficit developed over time. However this remained a subclinical feature as no pathology was observed in older mice in any muscles including the diaphragm, which is sensitive to mechanical load-induced damage. Conclusions/Significance This work shows that potential therapies in the dystroglycanopathies based on LARGE upregulation and α-dystroglycan hyperglycosylation in muscle should be safe.
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Affiliation(s)
- Martin Brockington
- Dubowitz Neuromuscular Centre, University College London (UCL) Institute of Child Health and Great Ormond Street Hospital, London, United Kingdom
| | - Silvia Torelli
- Dubowitz Neuromuscular Centre, University College London (UCL) Institute of Child Health and Great Ormond Street Hospital, London, United Kingdom
| | - Paul S. Sharp
- Department of Cellular and Molecular Neuroscience, Imperial College, London, United Kingdom
| | - Ke Liu
- Department of Cellular and Molecular Neuroscience, Imperial College, London, United Kingdom
| | - Sebahattin Cirak
- Dubowitz Neuromuscular Centre, University College London (UCL) Institute of Child Health and Great Ormond Street Hospital, London, United Kingdom
| | - Susan C. Brown
- Department of Veterinary Basic Science, Royal Veterinary College, London, United Kingdom
| | - Dominic J. Wells
- Department of Cellular and Molecular Neuroscience, Imperial College, London, United Kingdom
- Department of Veterinary Basic Science, Royal Veterinary College, London, United Kingdom
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, University College London (UCL) Institute of Child Health and Great Ormond Street Hospital, London, United Kingdom
- * E-mail:
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25
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Gumerson JD, Kabaeva ZT, Davis CS, Faulkner JA, Michele DE. Soleus muscle in glycosylation-deficient muscular dystrophy is protected from contraction-induced injury. Am J Physiol Cell Physiol 2010; 299:C1430-40. [PMID: 20844247 DOI: 10.1152/ajpcell.00192.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The glycosylation of dystroglycan is required for its function as a high-affinity laminin receptor, and loss of dystroglycan glycosylation results in congenital muscular dystrophy. The purpose of this study was to investigate the functional defects in slow- and fast-twitch muscles of glycosylation-deficient Large(myd) mice. While a partial alteration in glycosylation of dystroglycan in heterozygous Large(myd/+) mice was not sufficient to alter muscle function, homozygous Large(myd/myd) mice demonstrated a marked reduction in specific force in both soleus and extensor digitorum longus (EDL) muscles. Although EDL muscles from Large(myd/myd) mice were highly susceptible to lengthening contraction-induced injury, Large(myd/myd) soleus muscles surprisingly showed no greater force deficit compared with wild-type soleus muscles even after five lengthening contractions. Despite no increased susceptibility to injury, Large(myd/myd) soleus muscles showed loss of dystroglycan glycosylation and laminin binding activity and dystrophic pathology. Interestingly, we show that soleus muscles have a markedly higher sarcolemma expression of β(1)-containing integrins compared with EDL and gastrocnemius muscles. Therefore, we conclude that β(1)-containing integrins play an important role as matrix receptors in protecting muscles containing slow-twitch fibers from contraction-induced injury in the absence of dystroglycan function, and that contraction-induced injury appears to be a separable phenotype from the dystrophic pathology of muscular dystrophy.
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Affiliation(s)
- Jessica D Gumerson
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109-0622, USA
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26
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Muscular dystrophies: an update on pathology and diagnosis. Acta Neuropathol 2010; 120:343-58. [PMID: 20652576 DOI: 10.1007/s00401-010-0727-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 12/31/2022]
Abstract
Muscular dystrophies are clinically, genetically, and molecularly a heterogeneous group of neuromuscular disorders. Considerable advances have been made in recent years in the identification of causative genes, the differentiation of the different forms and in broadening the understanding of pathogenesis. Muscle pathology has an important role in these aspects, but correlation of the pathology with clinical phenotype is essential. Immunohistochemistry has a major role in differential diagnosis, particularly in recessive forms where an absence or reduction in protein expression can be detected. Several muscular dystrophies are caused by defects in genes encoding sarcolemmal proteins, several of which are known to interact. Others are caused by defects in nuclear membrane proteins or enzymes. Assessment of both primary and secondary abnormalities in protein expression is useful, in particular the hypoglycosylation of alpha-dystroglycan. In dominantly inherited muscular dystrophies it is rarely possible to detect a change in the expression of the primary defective protein; an exception to this is caveolin-3.
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27
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Canepari M, Pellegrino MA, D'Antona G, Bottinelli R. Skeletal muscle fibre diversity and the underlying mechanisms. Acta Physiol (Oxf) 2010; 199:465-76. [PMID: 20345415 DOI: 10.1111/j.1748-1716.2010.02118.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The review first briefly summarizes how myosin isoforms have been identified as the major determinant of the functional variability among skeletal muscle fibres. The latter feature is a major characteristic of muscle fibres and a major basis of skeletal muscle heterogeneity and plasticity in vivo. Then, evidence is reported, which indicates that the properties of muscle fibres can vary with no change in the myosin isoform they express. Moreover, the physiological and pathological conditions (ageing, disuse, exercise training, muscular dystrophy) in which such myosin isoform independent change in functional properties occurs and the possible underlying mechanisms are considered. Finally, the known molecular bases of the functional differences among slow and fast isoforms are briefly dealt with.
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Affiliation(s)
- M Canepari
- Department of Physiology and Interuniversity Institute of Myology, University of Pavia, Pavia, Italy
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28
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Dystrophins, utrophins, and associated scaffolding complexes: role in mammalian brain and implications for therapeutic strategies. J Biomed Biotechnol 2010; 2010:849426. [PMID: 20625423 PMCID: PMC2896903 DOI: 10.1155/2010/849426] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 03/14/2010] [Indexed: 12/23/2022] Open
Abstract
Two decades of molecular, cellular, and functional studies considerably increased our understanding of dystrophins function and unveiled the complex etiology of the cognitive deficits in Duchenne muscular dystrophy (DMD), which involves altered expression of several dystrophin-gene products in brain. Dystrophins are normally part of critical cytoskeleton-associated membrane-bound molecular scaffolds involved in the clustering of receptors, ion channels, and signaling proteins that contribute to synapse physiology and blood-brain barrier function. The utrophin gene also drives brain expression of several paralogs proteins, which cellular expression and biological roles remain to be elucidated. Here we review the structural and functional properties of dystrophins and utrophins in brain, the consequences of dystrophins loss-of-function as revealed by numerous studies in mouse models of DMD, and we discuss future challenges and putative therapeutic strategies that may compensate for the cognitive impairment in DMD based on experimental manipulation of dystrophins and/or utrophins brain expression.
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29
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Zhan Y, Melian NY, Pantoja M, Haines N, Ruohola-Baker H, Bourque CW, Rao Y, Carbonetto S. Dystroglycan and mitochondrial ribosomal protein L34 regulate differentiation in the Drosophila eye. PLoS One 2010; 5:e10488. [PMID: 20463973 PMCID: PMC2864756 DOI: 10.1371/journal.pone.0010488] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 04/09/2010] [Indexed: 11/21/2022] Open
Abstract
Mutations that diminish the function of the extracellular matrix receptor Dystroglycan (DG) result in muscular dystrophies, with associated neuronal migration defects in the brain and mental retardation e.g. Muscle Eye Brain Disease. To gain insight into the function of DG in the nervous system we initiated a study to examine its contribution to development of the eye of Drosophila melanogaster. Immuno-histochemistry showed that DG is concentrated on the apical surface of photoreceptors (R) cells during specification of cell-fate in the third instar larva and is maintained at this location through early pupal stages. In point mutations that are null for DG we see abortive R cell elongation during differentiation that first appears in the pupa and results in stunted R cells in the adult. Overexpression of DG in R cells results in a small but significant increase in their size. R cell differentiation defects appear at the same stage in a deficiency line Df(2R)Dg248 that affects Dg and the neighboring mitochondrial ribosomal gene, mRpL34. In the adult, these flies have severely disrupted R cells as well as defects in the lens and ommatidia. Expression of an mRpL34 transgene rescues much of this phenotype. We conclude that DG does not affect neuronal commitment but functions R cell autonomously to regulate neuronal elongation during differentiation in the pupa. We discuss these findings in view of recent work implicating DG as a regulator of cell metabolism and its genetic interaction with mRpL34, a member of a class of mitochondrial genes essential for normal metabolic function.
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Affiliation(s)
- Yougen Zhan
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
| | - Nadia Y. Melian
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
| | - Mario Pantoja
- Department of Biochemistry and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Nicola Haines
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
| | - Hannele Ruohola-Baker
- Department of Biochemistry and Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Charles W. Bourque
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
| | - Yong Rao
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
| | - Salvatore Carbonetto
- Centre for Research in Neuroscience, McGill University Health Centre, Montreal, Quebec, Canada
- * E-mail:
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Reed UC. Congenital muscular dystrophy. Part II: a review of pathogenesis and therapeutic perspectives. ARQUIVOS DE NEURO-PSIQUIATRIA 2010; 67:343-62. [PMID: 19547838 DOI: 10.1590/s0004-282x2009000200035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/14/2009] [Indexed: 11/22/2022]
Abstract
The congenital muscular dystrophies (CMDs) are a group of genetically and clinically heterogeneous hereditary myopathies with preferentially autosomal recessive inheritance, that are characterized by congenital hypotonia, delayed motor development and early onset of progressive muscle weakness associated with dystrophic pattern on muscle biopsy. The clinical course is broadly variable and can comprise the involvement of the brain and eyes. From 1994, a great development in the knowledge of the molecular basis has occurred and the classification of CMDs has to be continuously up dated. In the last number of this journal, we presented the main clinical and diagnostic data concerning the different subtypes of CMD. In this second part of the review, we analyse the main reports from the literature concerning the pathogenesis and the therapeutic perspectives of the most common subtypes of CMD: MDC1A with merosin deficiency, collagen VI related CMDs (Ullrich and Bethlem), CMDs with abnormal glycosylation of alpha-dystroglycan (Fukuyama CMD, Muscle-eye-brain disease, Walker Warburg syndrome, MDC1C, MDC1D), and rigid spine syndrome, another much rare subtype of CMDs not related with the dystrophin/glycoproteins/extracellular matrix complex.
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Mullen PJ, Lüscher B, Scharnagl H, Krähenbühl S, Brecht K. Effect of simvastatin on cholesterol metabolism in C2C12 myotubes and HepG2 cells, and consequences for statin-induced myopathy. Biochem Pharmacol 2009; 79:1200-9. [PMID: 20018177 DOI: 10.1016/j.bcp.2009.12.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 12/04/2009] [Accepted: 12/07/2009] [Indexed: 01/12/2023]
Abstract
The mechanism of statin-induced skeletal muscle myopathy is poorly understood. We investigated how simvastatin affects cholesterol metabolism, ubiquinone levels, and the prenylation and N-linked glycosylation of proteins in C2C12 myotubes. We used liver HepG2 cells for comparison, as their responses to statins are well-characterized in terms of their cholesterol metabolism (in contrast to muscle cells), and statins are well-tolerated in the liver. Differences between the two cell lines could indicate the mechanism behind statin-induced myopathy. Simvastatin reduced de novo cholesterol production in C2C12 myotubes by 95% after 18h treatment. The reduction was 82% in the HepG2 cells. Total cholesterol pools, however, remained constant in both cell lines. Simvastatin treatment similarly did not affect total ubiquinone levels in the myotubes, unlike in HepG2 cells (22% reduction in CoQ10). Statin treatment reduced levels of Ras and Rap1 prenylation in both cell lines, whereas N-linked glycosylation was only affected in C2C12 myotubes (21% reduction in rate). From these observations, we conclude that total cholesterol and ubiquinone levels are unlikely to be involved in statin-mediated myopathy, but reductions in protein prenylation and especially N-linked glycosylation may play a role. This first comparison of the responses to simvastatin between liver and skeletal muscle cell lines may be important for future research directions concerning statin-induced myopathy.
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Chang W, Winder TL, LeDuc CA, Simpson LL, Millar WS, Dungan J, Ginsberg N, Plaga S, Moore SA, Chung WK. Founder Fukutin mutation causes Walker-Warburg syndrome in four Ashkenazi Jewish families. Prenat Diagn 2009; 29:560-9. [PMID: 19266496 PMCID: PMC2735827 DOI: 10.1002/pd.2238] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Walker-Warburg syndrome (WWS) is a genetically heterogeneous congenital muscular dystrophy caused by abnormal glycosylation of alpha-dystroglycan (alpha-DG) that is associated with brain malformations and eye anomalies. The Fukutin (FKTN) gene, which causes autosomal recessively inherited WWS is most often associated with Fukuyama congenital muscular dystrophy in Japan. We describe the clinical features of four nonconsanguinous Ashkenazi Jewish families with WWS and identify the underlying genetic basis for WWS. METHOD We screened for mutations in POMGnT1, POMT1, POMT2, and FKTN, genes causing WWS, by dideoxy sequence analysis. RESULTS We identified an identical homozygous c.1167insA mutation in the FKTN gene on a common haplotype in all four families and identified 2/299 (0.7%) carriers for the c.1167insA mutation among normal American Ashkenazi Jewish adults. CONCLUSION These data suggest that the c.1167insA FKTN mutation described by us is a founder mutation that can be used to target diagnostic testing and carrier screening in the Ashkenazi Jewish population.
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Affiliation(s)
- Wendy Chang
- Division of Molecular Genetics, Department of Pediatrics, Columbia University Medical Center, New York, NY, USA.
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Abstract
Protein O-mannosylation is an essential modification in fungi and animals. Different from most other types of O-glycosylation, protein O-mannosylation is initiated in the endoplasmic reticulum by the transfer of mannose from dolichol monophosphate-activated mannose to serine and threonine residues of secretory proteins. In recent years, it has emerged that even bacteria are capable of O-mannosylation and that the biosynthetic pathway of O-mannosyl glycans is conserved between pro- and eukaryotes. In this review, we summarize the observations that have opened up the field and highlight characteristics of O-mannosylation in the different domains/kingdoms of life.
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Affiliation(s)
- Mark Lommel
- Department V Cell Chemistry, Heidelberg Institute for Plant Sciences, University of Heidelberg, Heidelberg, Germany
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35
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Heinonen TYK, Maki M. Peters'-plus syndrome is a congenital disorder of glycosylation caused by a defect in the beta1,3-glucosyltransferase that modifies thrombospondin type 1 repeats. Ann Med 2009; 41:2-10. [PMID: 18720094 DOI: 10.1080/07853890802301975] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Genetic defects in glycosyltransferases are responsible for a number of developmental defects and diseases known as congenital disorders of glycosylation (CDGs). Peters'-plus syndrome, a rare autosomal recessive disorder, is now known to be a CDG. This syndrome is characterized by a specific malformation of the eye that includes corneal opaqueness and iridocorneal adhesions (Peters' anomaly). Affected individuals are short in stature and have short limbs, and may have cleft lip/palate, defects in the central nervous system, heart, and various other organs. The phenotype varies in severity, ranging from death in early childhood to a general delay in growth and development, and is often associated with mental retardation. The mutations responsible for Peters'-plus syndrome inactivate a beta1,3-glucosyltransferase whose function is to add a glucose moiety to O-linked fucose, forming a rare glucose-beta1,3-fucose disaccharide. This disaccharide modification is specific to thrombospondin type 1 repeats (TSRs), domains found in extracellular proteins that function in cell-cell and cell-matrix interactions and signalling. Some ninety human proteins contain TSRs, but thus far the disaccharide has been demonstrated on only thrombospondin 1, properdin, F-spondin, ADAMTS-13, and ADAMTSL-1. These proteins perform essential functions in embryonic development, tissue remodelling, angiogenesis, neurogenesis, and complement activation. Identification of the beta1,3-glucosyltransferase and its substrate proteins is a key step towards understanding their roles in human development, and to uncovering the molecular and cellular mechanisms underlying the clinical manifestations of Peters'-plus syndrome.
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Affiliation(s)
- Taisto Y K Heinonen
- Paediatric Research Centre, University of Tampere and Tampere University Hospital, Tampere, Finland
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Kanagawa M, Nishimoto A, Chiyonobu T, Takeda S, Miyagoe-Suzuki Y, Wang F, Fujikake N, Taniguchi M, Lu Z, Tachikawa M, Nagai Y, Tashiro F, Miyazaki JI, Tajima Y, Takeda S, Endo T, Kobayashi K, Campbell KP, Toda T. Residual laminin-binding activity and enhanced dystroglycan glycosylation by LARGE in novel model mice to dystroglycanopathy. Hum Mol Genet 2008; 18:621-31. [PMID: 19017726 PMCID: PMC2638827 DOI: 10.1093/hmg/ddn387] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Hypoglycosylation and reduced laminin-binding activity of α-dystroglycan are common characteristics of dystroglycanopathy, which is a group of congenital and limb-girdle muscular dystrophies. Fukuyama-type congenital muscular dystrophy (FCMD), caused by a mutation in the fukutin gene, is a severe form of dystroglycanopathy. A retrotransposal insertion in fukutin is seen in almost all cases of FCMD. To better understand the molecular pathogenesis of dystroglycanopathies and to explore therapeutic strategies, we generated knock-in mice carrying the retrotransposal insertion in the mouse fukutin ortholog. Knock-in mice exhibited hypoglycosylated α-dystroglycan; however, no signs of muscular dystrophy were observed. More sensitive methods detected minor levels of intact α-dystroglycan, and solid-phase assays determined laminin binding levels to be ∼50% of normal. In contrast, intact α-dystroglycan is undetectable in the dystrophic Largemyd mouse, and laminin-binding activity is markedly reduced. These data indicate that a small amount of intact α-dystroglycan is sufficient to maintain muscle cell integrity in knock-in mice, suggesting that the treatment of dystroglycanopathies might not require the full recovery of glycosylation. To examine whether glycosylation defects can be restored in vivo, we performed mouse gene transfer experiments. Transfer of fukutin into knock-in mice restored glycosylation of α-dystroglycan. In addition, transfer of LARGE produced laminin-binding forms of α-dystroglycan in both knock-in mice and the POMGnT1 mutant mouse, which is another model of dystroglycanopathy. Overall, these data suggest that even partial restoration of α-dystroglycan glycosylation and laminin-binding activity by replacing or augmenting glycosylation-related genes might effectively deter dystroglycanopathy progression and thus provide therapeutic benefits.
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Affiliation(s)
- Motoi Kanagawa
- Division of Clinical Genetics, Department of Medical Genetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Ferland RJ, Batiz LF, Neal J, Lian G, Bundock E, Lu J, Hsiao YC, Diamond R, Mei D, Banham AH, Brown PJ, Vanderburg CR, Joseph J, Hecht JL, Folkerth R, Guerrini R, Walsh CA, Rodriguez EM, Sheen VL. Disruption of neural progenitors along the ventricular and subventricular zones in periventricular heterotopia. Hum Mol Genet 2008; 18:497-516. [PMID: 18996916 DOI: 10.1093/hmg/ddn377] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Periventricular heterotopia (PH) is a disorder characterized by neuronal nodules, ectopically positioned along the lateral ventricles of the cerebral cortex. Mutations in either of two human genes, Filamin A (FLNA) or ADP-ribosylation factor guanine exchange factor 2 (ARFGEF2), cause PH (Fox et al. in 'Mutations in filamin 1 prevent migration of cerebral cortical neurons in human periventricular heterotopia'. Neuron, 21, 1315-1325, 1998; Sheen et al. in 'Mutations in ARFGEF2 implicate vesicle trafficking in neural progenitor proliferation and migration in the human cerebral cortex'. Nat. Genet., 36, 69-76, 2004). Recent studies have shown that mutations in mitogen-activated protein kinase kinase kinase-4 (Mekk4), an indirect interactor with FlnA, also lead to periventricular nodule formation in mice (Sarkisian et al. in 'MEKK4 signaling regulates filamin expression and neuronal migration'. Neuron, 52, 789-801, 2006). Here we show that neurons in post-mortem human PH brains migrated appropriately into the cortex, that periventricular nodules were primarily composed of later-born neurons, and that the neuroependyma was disrupted in all PH cases. As studied in the mouse, loss of FlnA or Big2 function in neural precursors impaired neuronal migration from the germinal zone, disrupted cell adhesion and compromised neuroepithelial integrity. Finally, the hydrocephalus with hop gait (hyh) mouse, which harbors a mutation in Napa [encoding N-ethylmaleimide-sensitive factor attachment protein alpha (alpha-SNAP)], also develops a progressive denudation of the neuroepithelium, leading to periventricular nodule formation. Previous studies have shown that Arfgef2 and Napa direct vesicle trafficking and fusion, whereas FlnA associates dynamically with the Golgi membranes during budding and trafficking of transport vesicles. Our current findings suggest that PH formation arises from a final common pathway involving disruption of vesicle trafficking, leading to impaired cell adhesion and loss of neuroependymal integrity.
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Affiliation(s)
- Russell J Ferland
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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38
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Clement E, Mercuri E, Godfrey C, Smith J, Robb S, Kinali M, Straub V, Bushby K, Manzur A, Talim B, Cowan F, Quinlivan R, Klein A, Longman C, McWilliam R, Topaloglu H, Mein R, Abbs S, North K, Barkovich AJ, Rutherford M, Muntoni F. Brain involvement in muscular dystrophies with defective dystroglycan glycosylation. Ann Neurol 2008; 64:573-82. [DOI: 10.1002/ana.21482] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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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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40
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ten Hagen KG, Zhang L, Tian E, Zhang Y. Glycobiology on the fly: developmental and mechanistic insights from Drosophila. Glycobiology 2008; 19:102-11. [PMID: 18824561 DOI: 10.1093/glycob/cwn096] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Drosophila melanogaster offers many unique advantages for deciphering the complexities of glycan biosynthesis and function. The completion of the Drosophila genome sequencing project as well as the comprehensive catalogue of existing mutations and phenotypes have lead to a prolific database where many of the genes involved in glycan synthesis, assembly, modification, and recognition have been identified and characterized. Recent biochemical and molecular studies have elucidated the structure of the glycans present in Drosophila. Powerful genetic approaches have uncovered a number of critical biological roles for glycans during development that impact on our understanding of their function during mammalian development. Here, we summarize key recent findings and provide evidence for the usefulness of this model organism in unraveling the complexities of glycobiology across many species.
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Affiliation(s)
- Kelly G ten Hagen
- Developmental Glycobiology Unit, NIDCR, National Institutes of Health, Building 30, 30 Convent Drive, MSC 4370, Bethesda, MD 20892-4370, USA.
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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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Moore CJ, Goh HT, Hewitt JE. Genes required for functional glycosylation of dystroglycan are conserved in zebrafish. Genomics 2008; 92:159-67. [PMID: 18632251 DOI: 10.1016/j.ygeno.2008.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 05/12/2008] [Accepted: 05/14/2008] [Indexed: 10/21/2022]
Abstract
Mutations in human genes encoding proteins involved in alpha-dystroglycan glycosylation result in dystroglycanopathies: severe congenital muscular dystrophy phenotypes often accompanied by CNS abnormalities and ocular defects. We have identified the zebrafish orthologues of the seven known genes in this pathway and examined their expression during embryonic development. Zebrafish Large, POMT1, POMT2, POMGnT1, Fukutin, and FKRP show in situ hybridization patterns similar to those of dystroglycan, with broad expression throughout early development. By 30 h postfertilization (hpf), transcripts of all these genes are most prominent in the CNS, eye, and muscle, tissues that are predominantly affected in the dystroglycanopathies. In contrast, Large2 expression is more restricted and by 30 hpf is confined to the lens, cerebellum, and pronephric duct. We show that the monoclonal antibody IIH6, which recognizes a glycoform of dystroglycan, also detects the zebrafish protein. Injection of morpholino oligonucleotides against zebrafish Large2 resulted in loss of IIH6 immunostaining. These data indicate that the dystroglycan glycosylation pathway is conserved in zebrafish and suggest this organism is likely to be a useful model system for functional studies.
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Affiliation(s)
- Christopher J Moore
- Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
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43
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Phelan JA, Lowe LH, Glasier CM. Pediatric neurodegenerative white matter processes: leukodystrophies and beyond. Pediatr Radiol 2008; 38:729-49. [PMID: 18446335 DOI: 10.1007/s00247-008-0817-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 02/07/2008] [Accepted: 02/22/2008] [Indexed: 11/26/2022]
Abstract
Pediatric neurodegenerative white matter processes are complex, numerous and result from a vast array of causes ranging from white matter injury or inflammation to congenital metabolic disorders. When faced with a neurodegenerative white matter process on neuroimaging, the first step for the radiologist is to determine whether the findings represent a congenital metabolic leukodystrophy or one of various other white matter processes. In this review we first describe a general approach to neurodegenerative white matter disorders. We will briefly describe a few white matter diseases that mimic metabolic leukodystrophies. In the second half of the review we discuss an approach to distinguishing and classifying white matter leukodystrophies.
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Affiliation(s)
- Jonathan A Phelan
- Department of Radiology, Kansas City University of Medicine and Biosciences, University of Missouri-Kansas City, and The Children's Mercy Hospital and Clinics, 1750 Independence Ave., Kansas City, MO 64106, USA.
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Ackroyd MR, Skordis L, Kaluarachchi M, Godwin J, Prior S, Fidanboylu M, Piercy RJ, Muntoni F, Brown SC. Reduced expression of fukutin related protein in mice results in a model for fukutin related protein associated muscular dystrophies. Brain 2008; 132:439-51. [DOI: 10.1093/brain/awn335] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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45
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Lommel M, Willer T, Strahl S. POMT2, a key enzyme in Walker–Warburg syndrome: somatic sPOMT2, but not testis-specific tPOMT2, is crucial for mannosyltransferase activity in vivo. Glycobiology 2008; 18:615-25. [DOI: 10.1093/glycob/cwn042] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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46
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Teber S, Sezer T, Kafali M, Manzini MC, Konuk Yüksel B, Tekin M, Fitöz S, Walsh CA, Deda G. Severe muscle-eye-brain disease is associated with a homozygous mutation in the POMGnT1 gene. Eur J Paediatr Neurol 2008; 12:133-6. [PMID: 17881266 DOI: 10.1016/j.ejpn.2007.06.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 06/18/2007] [Accepted: 06/25/2007] [Indexed: 11/29/2022]
Abstract
Muscle-eye-brain (MEB) disease is an autosomal recessive disorder characterized by a broad clinical spectrum including congenital muscular dystrophy, ocular abnormalities, and brain malformation (type-II lissencephaly). Herein, we report on two Turkish siblings with a homozygous mutation in the POMGnT1 gene. A 6-year-old sibling has a severe form of MEB disease, which in some aspects is more suitable with the diagnosis of Walker-Warburg syndrome. However, the same mutation resulted in a less severe form of MEB in the older sibling, who is 14 years old. These two cases suggest that POMGnT1 mutations may cause MEB disease with different phenotypes even in the same family.
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Affiliation(s)
- Serap Teber
- Department of Pediatric Neurology, Ankara University School of Medicine of Pediatrics, 06510 Ankara, Turkey.
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47
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Genes, plasticity and mental retardation. Behav Brain Res 2008; 192:88-105. [PMID: 18329113 DOI: 10.1016/j.bbr.2008.01.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 01/16/2008] [Accepted: 01/16/2008] [Indexed: 11/23/2022]
Abstract
Functional and structural plasticity is a fundamental property of the brain involved in diverse processes ranging from brain construction and repair to storage of experiences during lifetime. Our current understanding of different forms of brain plasticity mechanisms has advanced tremendously in the last decades, benefiting from studies of development and memory storage in adulthood and from investigations of diverse diseased conditions. In this review, we focus on the role of mental retardation (MR) genes and show how this developing area of research can enrich our knowledge of the cellular and molecular mechanisms of brain plasticity and cognitive functions, and of the dysfunctional mechanisms underlying MR. We describe two main groups of MR genes; those leading to dysfunctional neurodevelopmental programs and brain malformations, and those which rely on alterations in molecular mechanisms underlying synaptic organization and plasticity. We first explore the role of MR genes in key mechanisms of neurogenesis and neuronal migration during development and in the adult, such as actin and microtubule-cytoskeletal dynamics and signal transduction. We then define the contribution of MR genes to forms of activity-dependent synaptic modifications, such as those involved in molecular organization of the synapse, intracellular signaling regulating gene programs and neuronal cytoskeleton to control network remodeling. We trace the characteristics of MR genes playing key roles in many forms of brain plasticity mechanisms, and highlight specific MR genes that endorse distinct roles in different cell types or brain regions, and at various times of a brain lifetime.
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Vainzof M, Ayub-Guerrieri D, Onofre PCG, Martins PCM, Lopes VF, Zilberztajn D, Maia LS, Sell K, Yamamoto LU. Animal models for genetic neuromuscular diseases. J Mol Neurosci 2008; 34:241-8. [PMID: 18202836 DOI: 10.1007/s12031-007-9023-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/05/2007] [Indexed: 10/22/2022]
Abstract
The neuromuscular disorders are a heterogeneous group of genetic diseases, caused by mutations in genes coding sarcolemmal, sarcomeric, and citosolic muscle proteins. Deficiencies or loss of function of these proteins leads to variable degree of progressive loss of motor ability. Several animal models, manifesting phenotypes observed in neuromuscular diseases, have been identified in nature or generated in laboratory. These models generally present physiological alterations observed in human patients and can be used as important tools for genetic, clinic, and histopathological studies. The mdx mouse is the most widely used animal model for Duchenne muscular dystrophy (DMD). Although it is a good genetic and biochemical model, presenting total deficiency of the protein dystrophin in the muscle, this mouse is not useful for clinical trials because of its very mild phenotype. The canine golden retriever MD model represents a more clinically similar model of DMD due to its larger size and significant muscle weakness. Autosomal recessive limb-girdle MD forms models include the SJL/J mice, which develop a spontaneous myopathy resulting from a mutation in the Dysferlin gene, being a model for LGMD2B. For the human sarcoglycanopahties (SG), the BIO14.6 hamster is the spontaneous animal model for delta-SG deficiency, whereas some canine models with deficiency of SG proteins have also been identified. More recently, using the homologous recombination technique in embryonic stem cell, several mouse models have been developed with null mutations in each one of the four SG genes. All sarcoglycan-null animals display a progressive muscular dystrophy of variable severity and share the property of a significant secondary reduction in the expression of the other members of the sarcoglycan subcomplex and other components of the Dystrophin-glycoprotein complex. Mouse models for congenital MD include the dy/dy (dystrophia-muscularis) mouse and the allelic mutant dy(2J)/dy(2J) mouse, both presenting significant reduction of alpha2-laminin in the muscle and a severe phenotype. The myodystrophy mouse (Large(myd)) harbors a mutation in the glycosyltransferase Large, which leads to altered glycosylation of alpha-DG, and also a severe phenotype. Other informative models for muscle proteins include the knockout mouse for myostatin, which demonstrated that this protein is a negative regulator of muscle growth. Additionally, the stress syndrome in pigs, caused by mutations in the porcine RYR1 gene, helped to localize the gene causing malignant hypertermia and Central Core myopathy in humans. The study of animal models for genetic diseases, in spite of the existence of differences in some phenotypes, can provide important clues to the understanding of the pathogenesis of these disorders and are also very valuable for testing strategies for therapeutic approaches.
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Affiliation(s)
- Mariz Vainzof
- Dept of Genetics and Evolutionary Biology, University of Sao Paulo, Sao Paulo, Brasil.
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49
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Haines N, Seabrooke S, Stewart BA. Dystroglycan and protein O-mannosyltransferases 1 and 2 are required to maintain integrity of Drosophila larval muscles. Mol Biol Cell 2007; 18:4721-30. [PMID: 17881734 PMCID: PMC2096576 DOI: 10.1091/mbc.e07-01-0047] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Accepted: 09/11/2007] [Indexed: 11/11/2022] Open
Abstract
In vertebrates, mutations in Protein O-mannosyltransferase1 (POMT1) or POMT2 are associated with muscular dystrophy due to a requirement for O-linked mannose glycans on the Dystroglycan (Dg) protein. In this study we examine larval body wall muscles of Drosophila mutant for Dg, or RNA interference knockdown for Dg and find defects in muscle attachment, altered muscle contraction, and a change in muscle membrane resistance. To determine if POMTs are required for Dg function in Drosophila, we examine larvae mutant for genes encoding POMT1 or POMT2. Larvae mutant for either POMT, or doubly mutant for both, show muscle attachment and muscle contraction phenotypes identical to those associated with reduced Dg function, consistent with a requirement for O-linked mannose on Drosophila Dg. Together these data establish a central role for Dg in maintaining integrity in Drosophila larval muscles and demonstrate the importance of glycosylation to Dg function in Drosophila. This study opens the possibility of using Drosophila to investigate muscular dystrophy.
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Affiliation(s)
- Nicola Haines
- Department of Biology, University of Toronto, Mississauga, ON, Canada L5L 1C6.
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50
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Boor I, Nagtegaal M, Kamphorst W, van der Valk P, Pronk JC, van Horssen J, Dinopoulos A, Bove KE, Pascual-Castroviejo I, Muntoni F, Estévez R, Scheper GC, van der Knaap MS. MLC1 is associated with the dystrophin-glycoprotein complex at astrocytic endfeet. Acta Neuropathol 2007; 114:403-10. [PMID: 17628813 PMCID: PMC2039857 DOI: 10.1007/s00401-007-0247-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 05/16/2007] [Accepted: 06/01/2007] [Indexed: 11/15/2022]
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a progressive cerebral white matter disease with onset in childhood, caused by mutations in the MLC1 gene. MLC1 is a protein with unknown function that is mainly expressed in the brain in astrocytic endfeet at the blood–brain and cerebrospinal fluid–brain barriers. It shares its localization at astrocytic endfeet with the dystrophin-associated glycoprotein complex (DGC). The objective of the present study was to investigate the possible association of MLC1 with the DGC. To test this hypothesis, (co)-localization of DGC-proteins and MLC1 was analyzed by immunohistochemical stainings in gliotic brain tissue from a patient with multiple sclerosis, in glioblastoma tissue and in brain tissue from an MLC patient. In control tissue, a direct protein interaction was tested by immunoprecipitation. Results revealed that MLC1 is co-localized with DGC-proteins in gliotic brain tissue. We demonstrated that both MLC1 and aquaporin-4, a member of the DGC, were redistributed in glioblastoma cells. In MLC brain tissue, we showed absence of MLC1 and altered expression of several DGC-proteins. We demonstrated a direct protein interaction between MLC1 and Kir4.1. From these results we conclude that MLC1 is associated with the DGC at astrocytic endfeet.
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Affiliation(s)
- Ilja Boor
- Department of Pediatrics/Child Neurology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
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