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Xu S, Li L, Shen L, Wang X, Feng W, Liu S. Unexpected partial RNA deletion by two different novel COL6A2 mutations leads to Ullrich congenital muscular dystrophy. QJM 2024; 117:61-62. [PMID: 37738610 DOI: 10.1093/qjmed/hcad209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Indexed: 09/24/2023] Open
Affiliation(s)
- S Xu
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - L Li
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, China
- Prenatal Diagnosis Center, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - L Shen
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, China
- Prenatal Diagnosis Center, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - X Wang
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, China
- Prenatal Diagnosis Center, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - W Feng
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - S Liu
- Medical Genetic Department, The Affiliated Hospital of Qingdao University, Qingdao, China
- Prenatal Diagnosis Center, The Affiliated Hospital of Qingdao University, Qingdao, China
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2
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Hollis JA, Chan MC, Malik HS, Campbell MG. Evolutionary origin and structural ligand mimicry by the inserted domain of alpha-integrin proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.05.565221. [PMID: 37986796 PMCID: PMC10659397 DOI: 10.1101/2023.11.05.565221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Heterodimeric integrin proteins transmit signals through conformational changes upon ligand binding between their alpha (α) and beta (β) subunits. Early in chordate evolution, some α subunits acquired an "inserted" (I) domain, which expanded their ligand binding capacity but simultaneously obstructed the ancestral ligand-binding pocket. While this would seemingly impede conventional ligand-mediated integrin activation, it was proposed that the I domain itself could serve both as a ligand replacement and an activation trigger. Here, we provide compelling evidence in support of this longstanding hypothesis using high-resolution cryo-electron microscopy structures of two distinct integrin complexes: the ligand-free and E-cadherin-bound states of the αEβ7 integrin with the I domain, as well as the α4β7 integrin lacking the I domain in both a ligand-free state and bound to MadCAM-1. We trace the evolutionary origin of the I domain to an ancestral collagen-collagen interaction domain. Our analyses illuminate how the I domain intrinsically mimics an extrinsic ligand, enabling integrins to undergo the canonical allosteric cascade of conformational activation and dramatically expanding the range of cellular communication mechanisms in vertebrates.
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Affiliation(s)
- Jeremy A. Hollis
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
- Graduate Program in Molecular and Cellular Biology, University of Washington; Seattle, WA 98195, USA
| | - Matthew C. Chan
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
| | - Harmit S. Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
- Howard Hughes Medical Institute; Seattle, WA 98109, USA
| | - Melody G. Campbell
- Division of Basic Sciences, Fred Hutchinson Cancer Center; Seattle, WA 98109, USA
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3
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Zanotti S, Magri F, Salani S, Napoli L, Ripolone M, Ronchi D, Fortunato F, Ciscato P, Velardo D, D’Angelo MG, Gualandi F, Nigro V, Sciacco M, Corti S, Comi GP, Piga D. Extracellular Matrix Disorganization and Sarcolemmal Alterations in COL6-Related Myopathy Patients with New Variants of COL6 Genes. Int J Mol Sci 2023; 24:5551. [PMID: 36982625 PMCID: PMC10059973 DOI: 10.3390/ijms24065551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
Collagen VI is a heterotrimeric protein expressed in several tissues and involved in the maintenance of cell integrity. It localizes at the cell surface, creating a microfilamentous network that links the cytoskeleton to the extracellular matrix. The heterotrimer consists of three chains encoded by COL6A1, COL6A2 and COL6A3 genes. Recessive and dominant molecular defects cause two main disorders, the severe Ullrich congenital muscular dystrophy and the relatively mild and slowly progressive Bethlem myopathy. We analyzed the clinical aspects, pathological features and mutational spectrum of 15 COL6-mutated patients belonging to our cohort of muscular dystrophy probands. Patients presented a heterogeneous phenotype ranging from severe forms to mild adult-onset presentations. Molecular analysis by NGS detected 14 different pathogenic variants, three of them so far unreported. Two changes, localized in the triple-helical domain of COL6A1, were associated with a more severe phenotype. Histological, immunological and ultrastructural techniques were employed for the validation of the genetic variants; they documented the high variability in COL6 distribution and the extracellular matrix disorganization, highlighting the clinical heterogeneity of our cohort. The combined use of these different technologies is pivotal in the diagnosis of COL6 patients.
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Affiliation(s)
- Simona Zanotti
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Francesca Magri
- Neurology Unit, Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Sabrina Salani
- Neurology Unit, Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Laura Napoli
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Michela Ripolone
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Dario Ronchi
- Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Francesco Fortunato
- Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Patrizia Ciscato
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Daniele Velardo
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | | | - Francesca Gualandi
- Medical Genetics Unit, Department of Medical Science, University of Ferrara, 44121 Ferrara, Italy
| | - Vincenzo Nigro
- Dipartimento di Medicina di Precisione, “Luigi Vanvitelli” University of Campania and Telethon Institute of Genetics and Medicine (TIGEM), 81100 Naples, Italy
| | - Monica Sciacco
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Neurology Unit, Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Stefania Corti
- Neurology Unit, Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Giacomo Pietro Comi
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
- Dino Ferrari Centre, Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122 Milan, Italy
| | - Daniela Piga
- Neurology Unit, Department of Neuroscience Foundation IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
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4
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Inoue M, Saito Y, Yonekawa T, Ogawa M, Iida A, Nishino I, Noguchi S. Causative variant profile of collagen VI-related dystrophy in Japan. Orphanet J Rare Dis 2021; 16:284. [PMID: 34167565 PMCID: PMC8223365 DOI: 10.1186/s13023-021-01921-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 06/13/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Collagen VI-related dystrophy spans a clinical continuum from severe Ullrich congenital muscular dystrophy to milder Bethlem myopathy. This disease is caused by causative variants in COL6A1, COL6A2, or COL6A3. Most reported causative variants are de novo; therefore, to identify possible associated causative variants, comprehensive large cohort studies are required for different ethnicities. METHODS We retrospectively reviewed clinical information, muscle histology, and genetic analyses from 147 Japanese patients representing 130 families, whose samples were sent for diagnosis to the National Center of Neurology and Psychiatry between July 1979 and January 2020. Genetic analyses were conducted by gene-based resequencing, targeted panel resequencing, and whole exome sequencing, in combination with cDNA analysis. RESULTS Of a total of 130 families with 1-5 members with collagen VI-related dystrophy, 120 had mono-allelic and 10 had bi-allelic variants in COL6A1, COL6A2, or COL6A3. Among them, 60 variants were in COL6A1, 57 in COL6A2, and 23 in COL6A3, including 37 novel variants. Mono-allelic variants were classified into four groups: missense (69, 58%), splicing (40, 33%), small in-frame deletion (7, 6%), and large genomic deletion (4, 3%). Variants in the triple helical domains accounted for 88% (105/120) of all mono-allelic variants. CONCLUSIONS We report the causative variant profile of a large set of Japanese cases of collagen VI-related dystrophy. This dataset can be used as a reference to support genetic diagnosis and variant-specific treatment.
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Affiliation(s)
- Michio Inoue
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Tokyo, Japan
| | - Yoshihiko Saito
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Tokyo, Japan
| | - Takahiro Yonekawa
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan
| | - Megumu Ogawa
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan
| | - Aritoshi Iida
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.,Department of Clinical Genome Analysis, Medical Genome Center, NCNP, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Tokyo, Japan.,Department of Clinical Genome Analysis, Medical Genome Center, NCNP, Tokyo, Japan
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8502, Japan.
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5
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Simsek-Kiper PO, Oguz S, Ergen FB, Utine GE, Alikasifoglu M, Haliloglu G. A Revisited Diagnosis of Collagen VI Related Muscular Dystrophy in a Patient with a Novel COL6A2 Variant and 21q22.3 Deletion. Neuropediatrics 2020; 51:445-449. [PMID: 32663882 DOI: 10.1055/s-0040-1714125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The genetic etiology of collagen VI related muscular dystrophies is heterogenous. Genomic deletions in one allele involving COL6A2 or both COL6A1 and COL6A2 unmasking a pathogenic variant in the second nondeleted allele have been described in the etiology. We aimed to report the clinical and molecular findings of a 13-year-old boy with ring chromosome 21 who presented to our clinic with easy fatigability, muscle weakness, and waddling gait. Phenotypic delineation along with chromosomal microarray analysis and DNA sequencing were performed. Affymetrix CytoScan Optima array platform and DNA sequencing revealed a 2,202 kb de novo deletion at 21q22.3, including COL6A1 and COL6A2, and a novel heterozygous variant at position c.2875G > A;p.(Glu959Lys) in COL6A2, respectively. Before his admission to our center, the patient was evaluated for hypotonia elsewhere when he was 15 months old. He was diagnosed with ring chromosome 21 on peripheral blood karyotype analysis; however, no further assessment was performed at that time. He had normal growth with mild dysmorphic facial features, distal laxity, gastrocnemius hypertrophy, proximal muscle weakness, increased lordotic posture with mild flexion contractures at the knees, and gait disturbance. Although the phenotype does not fit into classical Ullrich congenital muscular dystrophies, muscle magnetic resonance imaging (MRI) revealed a complementary pattern consistent with collagen VI related myopathies. Genetic testing confirmed the clinical diagnosis as well. This patient yet represents another example of the effect of large genomic deletions leading to recessive disorders through unmasking a pathogenic variant in the second nondeleted allele.
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Affiliation(s)
| | - Sumeyra Oguz
- Department of Medical Genetics, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Fatma Bilge Ergen
- Department of Radiology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Gulen Eda Utine
- Department of Pediatric Genetics, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Mehmet Alikasifoglu
- Department of Medical Genetics, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Goknur Haliloglu
- Department of Pediatric Neurology, Hacettepe University Faculty of Medicine, Ankara, Turkey
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6
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Bielajew BJ, Hu JC, Athanasiou KA. Collagen: quantification, biomechanics, and role of minor subtypes in cartilage. NATURE REVIEWS. MATERIALS 2020; 5:730-747. [PMID: 33996147 PMCID: PMC8114887 DOI: 10.1038/s41578-020-0213-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/28/2020] [Indexed: 05/02/2023]
Abstract
Collagen is a ubiquitous biomaterial in vertebrate animals. Although each of its 28 subtypes contributes to the functions of many different tissues in the body, most studies on collagen or collagenous tissues have focussed on only one or two subtypes. With recent developments in analytical chemistry, especially mass spectrometry, significant advances have been made toward quantifying the different collagen subtypes in various tissues; however, high-throughput and low-cost methods for collagen subtype quantification do not yet exist. In this Review, we introduce the roles of collagen subtypes and crosslinks, and describe modern assays that enable a deep understanding of tissue physiology and disease states. Using cartilage as a model tissue, we describe the roles of major and minor collagen subtypes in detail; discuss known and unknown structure-function relationships; and show how tissue engineers may harness the functional characteristics of collagen to engineer robust neotissues.
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Affiliation(s)
- Benjamin J. Bielajew
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA
| | - Jerry C. Hu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA
| | - Kyriacos A. Athanasiou
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA
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7
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Solomon-Degefa H, Gebauer JM, Jeffries CM, Freiburg CD, Meckelburg P, Bird LE, Baumann U, Svergun DI, Owens RJ, Werner JM, Behrmann E, Paulsson M, Wagener R. Structure of a collagen VI α3 chain VWA domain array: adaptability and functional implications of myopathy causing mutations. J Biol Chem 2020; 295:12755-12771. [PMID: 32719005 DOI: 10.1074/jbc.ra120.014865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/16/2020] [Indexed: 12/23/2022] Open
Abstract
Collagen VI is a ubiquitous heterotrimeric protein of the extracellular matrix (ECM) that plays an essential role in the proper maintenance of skeletal muscle. Mutations in collagen VI lead to a spectrum of congenital myopathies, from the mild Bethlem myopathy to the severe Ullrich congenital muscular dystrophy. Collagen VI contains only a short triple helix and consists primarily of von Willebrand factor type A (VWA) domains, protein-protein interaction modules found in a range of ECM proteins. Disease-causing mutations occur commonly in the VWA domains, and the second VWA domain of the α3 chain, the N2 domain, harbors several such mutations. Here, we investigate structure-function relationships of the N2 mutations to shed light on their possible myopathy mechanisms. We determined the X-ray crystal structure of N2, combined with monitoring secretion efficiency in cell culture of selected N2 single-domain mutants, finding that mutations located within the central core of the domain severely affect secretion efficiency. In longer α3 chain constructs, spanning N6-N3, small-angle X-ray scattering demonstrates that the tandem VWA array has a modular architecture and samples multiple conformations in solution. Single-particle EM confirmed the presence of multiple conformations. Structural adaptability appears intrinsic to the VWA domain region of collagen VI α3 and has implications for binding interactions and modulating stiffness within the ECM.
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Affiliation(s)
| | - Jan M Gebauer
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Cy M Jeffries
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Carolin D Freiburg
- Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | | | - Louise E Bird
- The Research Complex at Harwell, Rutherford Appleton Laboratory Harwell, Oxford, United Kingdom.,Structural Biology Division, Wellcome Human Genetics Centre, University of Oxford, Oxford, United Kingdom
| | - Ulrich Baumann
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Dmitri I Svergun
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Raymond J Owens
- The Research Complex at Harwell, Rutherford Appleton Laboratory Harwell, Oxford, United Kingdom.,Structural Biology Division, Wellcome Human Genetics Centre, University of Oxford, Oxford, United Kingdom
| | - Jörn M Werner
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Elmar Behrmann
- Institute of Biochemistry, University of Cologne, Cologne, Germany.,Max Planck Research Group Structural Dynamics of Proteins, Center of Advanced European Studies and Research (caesar), Bonn, Germany
| | - Mats Paulsson
- Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.,Center for Molecular Medicine (CMMC), Cologne, Germany.,Cologne Center for Musculoskeletal Biomechanics (CCMB), Cologne, Germany
| | - Raimund Wagener
- Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany .,Center for Molecular Medicine (CMMC), Cologne, Germany.,Cologne Center for Musculoskeletal Biomechanics (CCMB), Cologne, Germany
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8
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Caria F, Cescon M, Gualandi F, Pichiecchio A, Rossi R, Rimessi P, Piccinelli SC, Cassarino SG, Gregorio I, Galvagni A, Ferlini A, Padovani A, Bonaldo P, Filosto M. WITHDRAWN: Autosomal recessive Bethlem myopathy: A clinical, genetic and functional study. Neuromuscul Disord 2019. [DOI: 10.1016/j.nmd.2019.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Caria F, Cescon M, Gualandi F, Pichiecchio A, Rossi R, Rimessi P, Cotti Piccinelli S, Gallo Cassarino S, Gregorio I, Galvagni A, Ferlini A, Padovani A, Bonaldo P, Filosto M. Autosomal recessive Bethlem myopathy: A clinical, genetic and functional study. Neuromuscul Disord 2019; 29:657-663. [PMID: 31471117 DOI: 10.1016/j.nmd.2019.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 06/03/2019] [Accepted: 07/16/2019] [Indexed: 01/04/2023]
Abstract
Bethlem myopathy represents the milder form of the spectrum of Collagen VI-related dystrophies, which are characterized by a clinical continuum between the two extremities, the Bethlem myopathy and the Ullrich congenital muscular dystrophy, and include less defined intermediate phenotypes. Bethlem myopathy is mainly an autosomal dominant disorder and the causing mutations occur in the COL6A genes encoding for the α1 (COL6A1), α2 (COL6A2) and α3 (COL6A3) chains. However, few cases of recessive inheritance have been also reported. We here describe clinical, genetic and functional findings in a recessive Bethlem myopathy family harbouring two novel pathogenic mutations in the COL6A2 gene. Two adult siblings presented with muscle weakness and wasting, elbows and Achilles tendon retractions, lumbar hyperlordosis, waddling gait and positive Gowers' sign. Muscle biopsy showed a dystrophic pattern. Molecular analysis of the COL6A2 gene revealed the novel paternally-inherited nonsense p.Gln889* mutation and the maternally-inherited p.Pro260_Lys261insProPro small insertion. Fibroblast studies in both affected patients showed the concomitant reduction in the amount of normal Collagen VI (p.Gln889*) and impairment of Collagen VI secretion and assembly (p.Pro260_Lys261insProPro). Each of the two variants behave as a recessive mutation as shown by the asymptomatic heterozygous parents, while their concomitant effects determined a relatively mild Bethlem myopathy phenotype. This study confirms the occurrence of recessive inherited Bethlem myopathy and expands the genetic heterogeneity of this group of muscle diseases.
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Affiliation(s)
- Filomena Caria
- Center for Neuromuscular Diseases, Unit of Neurology, ASST "Spedali Civili", Brescia, Italy
| | - Matilde Cescon
- Department of Molecular Medicine, University of Padova, Italy
| | | | - Anna Pichiecchio
- IRCCS Mondino Foundation, Pavia, Italy; University of Pavia, Italy
| | - Rachele Rossi
- UOL of Medical Genetics, University-Hospital S'Anna- Ferrara, Italy
| | - Paola Rimessi
- UOL of Medical Genetics, University-Hospital S'Anna- Ferrara, Italy
| | | | - Serena Gallo Cassarino
- Center for Neuromuscular Diseases, Unit of Neurology, ASST "Spedali Civili", Brescia, Italy
| | - Ilaria Gregorio
- Department of Molecular Medicine, University of Padova, Italy
| | - Anna Galvagni
- Center for Neuromuscular Diseases, Unit of Neurology, ASST "Spedali Civili", Brescia, Italy
| | | | - Alessandro Padovani
- Center for Neuromuscular Diseases, Unit of Neurology, ASST "Spedali Civili", Brescia, Italy
| | - Paolo Bonaldo
- Department of Molecular Medicine, University of Padova, Italy
| | - Massimiliano Filosto
- Center for Neuromuscular Diseases, Unit of Neurology, ASST "Spedali Civili", Brescia, Italy.
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10
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Lamandé SR, Bateman JF. Genetic Disorders of the Extracellular Matrix. Anat Rec (Hoboken) 2019; 303:1527-1542. [PMID: 30768852 PMCID: PMC7318566 DOI: 10.1002/ar.24086] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022]
Abstract
Mutations in the genes for extracellular matrix (ECM) components cause a wide range of genetic connective tissues disorders throughout the body. The elucidation of mutations and their correlation with pathology has been instrumental in understanding the roles of many ECM components. The pathological consequences of ECM protein mutations depend on its tissue distribution, tissue function, and on the nature of the mutation. The prevalent paradigm for the molecular pathology has been that there are two global mechanisms. First, mutations that reduce the production of ECM proteins impair matrix integrity largely due to quantitative ECM defects. Second, mutations altering protein structure may reduce protein secretion but also introduce dominant negative effects in ECM formation, structure and/or stability. Recent studies show that endoplasmic reticulum (ER) stress, caused by mutant misfolded ECM proteins, makes a significant contribution to the pathophysiology. This suggests that targeting ER‐stress may offer a new therapeutic strategy in a range of ECM disorders caused by protein misfolding mutations. Anat Rec, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Shireen R Lamandé
- Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville Victoria, Australia.,Department of Paediatrics, University of Melbourne, Parkville Victoria, Australia
| | - John F Bateman
- Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville Victoria, Australia.,Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville Victoria, Australia
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11
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Asteggiano CG, Papazoglu M, Bistué Millón MB, Peralta MF, Azar NB, Spécola NS, Guelbert N, Suldrup NS, Pereyra M, Dodelson de Kremer R. Ten years of screening for congenital disorders of glycosylation in Argentina: case studies and pitfalls. Pediatr Res 2018; 84:837-841. [PMID: 30397276 DOI: 10.1038/s41390-018-0206-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/19/2018] [Accepted: 09/25/2018] [Indexed: 11/09/2022]
Abstract
BACKGROUND Congenital Disorders of Glycosylation (CDG) are genetic diseases caused by hypoglycosylation of glycoproteins and glycolipids. Most CDG are multisystem disorders with mild to severe involvement. METHODS We studied 554 patients (2007-2017) with a clinical phenotype compatible with a CDG. Screening was performed by serum transferrin isoelectric focusing. The diagnosis was confirmed by genetic testing (Sanger or exome sequencing). RESULTS A confirmed abnormal pattern was found in nine patients. Seven patients showed a type 1 pattern: four with PMM2-CDG, two with ALG2-CDG, and one with classical galactosemia. A type 2 pattern was found in two patients: one with a CDG-IIx and one with a transferrin protein variant. Abnormal transferrin pattern were observed in a patient with a myopathy due to a COL6A2 gene variant. CONCLUSIONS CDG screening in Argentina from 2007 to 2017 revealed 4 PMM2-CDG patients, 2 ALG2-CDG patients with a novel homozygous gene variant and 1 CDG-IIx.
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Affiliation(s)
- Carla Gabriela Asteggiano
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina.
| | - Magali Papazoglu
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - María Beatriz Bistué Millón
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - María Fernanda Peralta
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | - Nydia Beatriz Azar
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
| | | | - Norberto Guelbert
- Servicio de Enfermedades Metabólicas, Hospital de Niños de la Sma. Trinidad, Ferroviarios 1250, Córdoba, Argentina
| | | | - Marcela Pereyra
- Servicio de Crecimiento y Desarrollo, Hospital Pediátrico Humberto Notti, Mendoza, Argentina
| | - Raquel Dodelson de Kremer
- CONICET - UCC - Centro de Estudio de las Metabolopatías Congénitas (CEMECO), Hospital de Niños de la Sma. Trinidad, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Ferroviarios 1250, Córdoba, Argentina
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Lamandé SR, Bateman JF. Collagen VI disorders: Insights on form and function in the extracellular matrix and beyond. Matrix Biol 2017; 71-72:348-367. [PMID: 29277723 DOI: 10.1016/j.matbio.2017.12.008] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/13/2017] [Accepted: 12/16/2017] [Indexed: 12/18/2022]
Abstract
Mutations in the three canonical collagen VI genes, COL6A1, COL6A2 and COL6A3, cause a spectrum of muscle disease from Bethlem myopathy at the mild end to the severe Ullrich congenital muscular dystrophy. Mutations can be either dominant or recessive and the resulting clinical severity is influenced by the way mutations impact the complex collagen VI assembly process. Most mutations are found towards the N-terminus of the triple helical collagenous domain and compromise extracellular microfibril assembly. Outside the triple helix collagen VI is highly polymorphic and discriminating mutations from rare benign changes remains a major diagnostic challenge. Collagen VI deficiency alters extracellular matrix structure and biomechanical properties and leads to increased apoptosis and oxidative stress, decreased autophagy, and impaired muscle regeneration. Therapies that target these downstream consequences have been tested in a collagen VI null mouse and also in small human trials where they show modest clinical efficacy. An important role for collagen VI in obesity, cancer and diabetes is emerging. A major barrier to developing effective therapies is the paucity of information about how collagen VI deficiency in the extracellular matrix signals the final downstream consequences - the receptors involved and the intracellular messengers await further characterization.
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Affiliation(s)
- Shireen R Lamandé
- Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Vic, Australia; Department of Paediatrics, University of Melbourne, Parkville, Vic, Australia.
| | - John F Bateman
- Musculoskeletal Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Vic, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Vic, Australia
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Sabatelli P, Gualandi F, Bonaldo P, Merlini L. Detecting collagen VI in Bethlem myopathy. J Biol Chem 2015; 290:8011. [PMID: 25795730 DOI: 10.1074/jbc.l115.639088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Patrizia Sabatelli
- Institute of molecular Genetics-CNR, SC Laboratory of Musculoskeletal Cell Biology, IOR, 40136 Bologna, Italy,
| | | | - Paolo Bonaldo
- Department of Molecular Medicine, University of Padova, Padova, Italy, and
| | - Luciano Merlini
- SC Laboratory of Musculoskeletal Cell Biology, IOR, Bologna, Italy
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14
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Zamurs LK, Idoate MA, Hanssen E, Gomez-Ibañez A, Pastor P, Lamandé SR. Aberrant mitochondria in a Bethlem myopathy patient with a homozygous amino acid substitution that destabilizes the collagen VI α2(VI) chain. J Biol Chem 2014; 290:4272-81. [PMID: 25533456 DOI: 10.1074/jbc.m114.632208] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bethlem myopathy and Ullrich congenital muscular dystrophy (UCMD) sit at opposite ends of a clinical spectrum caused by mutations in the extracellular matrix protein collagen VI. Bethlem myopathy is relatively mild, and patients remain ambulant in adulthood while many UCMD patients lose ambulation by their teenage years and require respiratory interventions. Dominant and recessive mutations are found across the entire clinical spectrum; however, recessive Bethlem myopathy is rare, and our understanding of the molecular pathology is limited. We studied a patient with Bethlem myopathy. Electron microscopy of his muscle biopsy revealed abnormal mitochondria. We identified a homozygous COL6A2 p.D871N amino acid substitution in the C-terminal C2 A-domain. Mutant α2(VI) chains are unable to associate with α1(VI) and α3(VI) and are degraded by the proteasomal pathway. Some collagen VI is assembled, albeit more slowly than normal, and is secreted. These molecules contain the minor α2(VI) C2a splice form that has an alternative C terminus that does include the mutation. Collagen VI tetramers containing the α2(VI) C2a chain do not assemble efficiently into microfibrils and there is a severe collagen VI deficiency in the extracellular matrix. We expressed wild-type and mutant α2(VI) C2 domains in mammalian cells and showed that while wild-type C2 domains are efficiently secreted, the mutant p.D871N domain is retained in the cell. These studies shed new light on the protein domains important for intracellular and extracellular collagen VI assembly and emphasize the importance of molecular investigations for families with collagen VI disorders to ensure accurate diagnosis and genetic counseling.
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Affiliation(s)
- Laura K Zamurs
- From the Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia
| | | | - Eric Hanssen
- Electron Microscopy Unit, Bio21 Molecular Science and Biotechnology Institute and
| | - Asier Gomez-Ibañez
- Neurology, Clínica Universidad de Navarra, University of Navarra School of Medicine, 31008 Pamplona, Spain
| | - Pau Pastor
- Neurology, Clínica Universidad de Navarra, University of Navarra School of Medicine, 31008 Pamplona, Spain, Neurogenetics Laboratory, Division of Neurosciences, Center for Applied Medical Research, Universidad de Navarra, 31008 Pamplona, Spain, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28220 Madrid, Spain
| | - Shireen R Lamandé
- From the Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville 3052, Australia, Department of Paediatrics, University of Melbourne, Parkville 3010, Australia,
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15
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Bönnemann CG, Wang CH, Quijano-Roy S, Deconinck N, Bertini E, Ferreiro A, Muntoni F, Sewry C, Béroud C, Mathews KD, Moore SA, Bellini J, Rutkowski A, North KN. Diagnostic approach to the congenital muscular dystrophies. Neuromuscul Disord 2014; 24:289-311. [PMID: 24581957 PMCID: PMC5258110 DOI: 10.1016/j.nmd.2013.12.011] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/23/2013] [Accepted: 12/31/2013] [Indexed: 12/14/2022]
Abstract
Congenital muscular dystrophies (CMDs) are early onset disorders of muscle with histological features suggesting a dystrophic process. The congenital muscular dystrophies as a group encompass great clinical and genetic heterogeneity so that achieving an accurate genetic diagnosis has become increasingly challenging, even in the age of next generation sequencing. In this document we review the diagnostic features, differential diagnostic considerations and available diagnostic tools for the various CMD subtypes and provide a systematic guide to the use of these resources for achieving an accurate molecular diagnosis. An International Committee on the Standard of Care for Congenital Muscular Dystrophies composed of experts on various aspects relevant to the CMDs performed a review of the available literature as well as of the unpublished expertise represented by the members of the committee and their contacts. This process was refined by two rounds of online surveys and followed by a three-day meeting at which the conclusions were presented and further refined. The combined consensus summarized in this document allows the physician to recognize the presence of a CMD in a child with weakness based on history, clinical examination, muscle biopsy results, and imaging. It will be helpful in suspecting a specific CMD subtype in order to prioritize testing to arrive at a final genetic diagnosis.
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Affiliation(s)
- Carsten G Bönnemann
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.
| | - Ching H Wang
- Driscoll Children's Hospital, Corpus Christi, TX, United States
| | - Susana Quijano-Roy
- Hôpital Raymond Poincaré, Garches, and UFR des sciences de la santé Simone Veil (UVSQ), France
| | - Nicolas Deconinck
- Hôpital Universitaire des Enfants Reine Fabiola, Brussels and Ghent University Hospital, Ghent, Belgium
| | | | - Ana Ferreiro
- UMR787 INSERM/UPMC and Reference Center for Neuromuscular Disorders, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, United Kingdom
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, United Kingdom
| | - Christophe Béroud
- INSERM U827, Laboratoire de Génétique Moleculaire, Montpellier, France
| | | | | | - Jonathan Bellini
- Stanford University School of Medicine, Stanford, CA, United States
| | | | - Kathryn N North
- Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
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Alexeev V, Arita M, Donahue A, Bonaldo P, Chu ML, Igoucheva O. Human adipose-derived stem cell transplantation as a potential therapy for collagen VI-related congenital muscular dystrophy. Stem Cell Res Ther 2014; 5:21. [PMID: 24522088 PMCID: PMC4054951 DOI: 10.1186/scrt411] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 12/20/2013] [Indexed: 12/16/2022] Open
Abstract
Introduction Congenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of neuromuscular disorders characterized by muscle weakness within the first two years of life. Collagen VI-related muscle disorders have recently emerged as one of the most common types of CMD. COL6 CMD is caused by deficiency and/or dysfunction of extracellular matrix (ECM) protein collagen VI. Currently, there is no specific treatment for this disabling and life-threatening disease. The primary cellular targets for collagen VI CMD therapy are fibroblasts in muscle, tendon and skin, as opposed to muscle cells for other types of muscular dystrophies. However, recent advances in stem cell research have raised the possibility that use of adult stem cells may provide dramatic new therapies for treatment of COL6 CMD. Methods Here, we developed a procedure for isolation of human stem cells from the adipose layer of neonatal skin. The adipose-derived stem cells (ADSC) were examined for expression of ECM and related genes using gene expression array analysis. The therapeutic potential of ADSC was assessed after a single intramuscular transplantation in collagen VI-deficient mice. Results Analysis of primary cultures confirmed that established ADSC represent a morphologically homogenous population with phenotypic and functional features of adult mesenchymal stem cells. A comprehensive gene expression analysis showed that ADSC express a vast array of ECM genes. Importantly, it was observed that ADSC synthesize and secrete all three collagen VI chains, suggesting suitability of ADSC for COL6 CMD treatment. Furthermore, we have found that a single intramuscular transplantation of ADSC into Col6a1−/−Rag1−/− mice under physiological and cardiotoxin-induced injury/regeneration conditions results in efficient engraftment and migration of stem cells within the skeletal muscle. Importantly, we showed that ADSC can survive long-term and continuously secrete the therapeutic collagen VI protein missing in the mutant mice. Conclusions Overall, our findings suggest that stem cell therapy can potentially provide a new avenue for the treatment of COL6 CMD and other muscular disorders and injuries.
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Comparison of gene expression profiles in primary and immortalized human pterygium fibroblast cells. Exp Cell Res 2013; 319:2781-9. [PMID: 24012806 DOI: 10.1016/j.yexcr.2013.08.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 08/19/2013] [Accepted: 08/23/2013] [Indexed: 01/18/2023]
Abstract
PURPOSE Pterygium is a fibrovascular growth on the ocular surface with corneal tissue destruction, matrix degradation and varying extents of chronic inflammation. To facilitate investigation of pterygium etiology, we immortalized pterygium fibroblast cells and profiled their global transcript levels compared to primary cultured cells. METHODS Fibroblast cells were cultured from surgically excised pterygium tissue using the explant method and propagated to passage number 2-4. We hypothesized that intervention with 3 critical molecular intermediates may be necessary to propage these cells. Primary fibroblast cells were immortalized sequentially by a retroviral construct containing the human telomerase reverse transcriptase gene and another retroviral expression vector expressing p53/p16 shRNAs. Primary and immortalized fibroblast cells were evaluated for differences in global gene transcript levels using an Agilent Genechip microarray. RESULTS Light microscopic morphology of immortalized cells was similar to primary pterygium fibroblast at passage 2-4. Telomerase reverse transcriptase was expressed, and p53 and p16 levels were reduced in immortalized pterygium fibroblast cells. There were 3308 significantly dysregulated genes showing at least 2 fold changes in transcript levels between immortalized and primary cultured cells (2005 genes were up-regulated and 1303 genes were down-regulated). Overall, 13.58% (95% CI: 13.08-14.10) of transcripts in immortalized cells were differentially expressed by at least 2 folds compared to primary cells. CONCLUSION Pterygium primary fibroblast cells were successfully immortalized to at least passage 11. Although a variety of genes are differentially expressed between immortalized and primary cells, only genes related to cell cycle are significantly changed, suggesting that the immortalized cells may be used as an in vitro model for pterygium pathology.
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Eymard B, Ferreiro A, Ben Yaou R, Stojkovic T. Muscle diseases with prominent joint contractures: Main entities and diagnostic strategy. Rev Neurol (Paris) 2013; 169:546-63. [DOI: 10.1016/j.neurol.2013.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 01/13/2023]
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ColVI myopathies: where do we stand, where do we go? Skelet Muscle 2011; 1:30. [PMID: 21943391 PMCID: PMC3189202 DOI: 10.1186/2044-5040-1-30] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 09/23/2011] [Indexed: 02/08/2023] Open
Abstract
Collagen VI myopathies, caused by mutations in the genes encoding collagen type VI (ColVI), represent a clinical continuum with Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) at each end of the spectrum, and less well-defined intermediate phenotypes in between. ColVI myopathies also share common features with other disorders associated with prominent muscle contractures, making differential diagnosis difficult. This group of disorders, under-recognized for a long time, has aroused much interest over the past decade, with important advances made in understanding its molecular pathogenesis. Indeed, numerous mutations have now been reported in the COL6A1, COL6A2 and COL6A3 genes, a large proportion of which are de novo and exert dominant-negative effects. Genotype-phenotype correlations have also started to emerge, which reflect the various pathogenic mechanisms at play in these disorders: dominant de novo exon splicing that enables the synthesis and secretion of mutant tetramers and homozygous nonsense mutations that lead to premature termination of translation and complete loss of function are associated with early-onset, severe phenotypes. In this review, we present the current state of diagnosis and research in the field of ColVI myopathies. The past decade has provided significant advances, with the identification of altered cellular functions in animal models of ColVI myopathies and in patient samples. In particular, mitochondrial dysfunction and a defect in the autophagic clearance system of skeletal muscle have recently been reported, thereby opening potential therapeutic avenues.
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Abstract
The collagen VI-related myopathy known as Ullrich congenital muscular dystrophy is an early-onset disease that combines substantial muscle weakness with striking joint laxity and progressive contractures. Patients might learn to walk in early childhood; however, this ability is subsequently lost, concomitant with the development of frequent nocturnal respiratory failure. Patients with intermediate phenotypes of collagen VI-related myopathy display a lesser degree of weakness and a longer period of ambulation than do individuals with Ullrich congenital muscular dystrophy, and the spectrum of disease finally encompasses mild Bethlem myopathy, in which ambulation persists into adulthood. Dominant and recessive autosomal mutations in the three major collagen VI genes-COL6A1, COL6A2, and COL6A3-can underlie this entire clinical spectrum, and result in deficient or dysfunctional microfibrillar collagen VI in the extracellular matrix of muscle and other connective tissues, such as skin and tendons. The potential effects on muscle include progressive dystrophic changes, fibrosis and evidence for increased apoptosis, which potentially open avenues for pharmacological intervention. Optimized respiratory management, including noninvasive nocturnal ventilation together with careful orthopedic management, are the current mainstays of treatment and have already led to a considerable improvement in life expectancy for children with Ullrich congenital muscular dystrophy.
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Tooley LD, Zamurs LK, Beecher N, Baker NL, Peat RA, Adams NE, Bateman JF, North KN, Baldock C, Lamandé SR. Collagen VI microfibril formation is abolished by an {alpha}2(VI) von Willebrand factor type A domain mutation in a patient with Ullrich congenital muscular dystrophy. J Biol Chem 2010; 285:33567-33576. [PMID: 20729548 PMCID: PMC2963345 DOI: 10.1074/jbc.m110.152520] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/22/2010] [Indexed: 11/06/2022] Open
Abstract
Collagen VI is an extracellular protein that most often contains the three genetically distinct polypeptide chains, α1(VI), α2(VI), and α3(VI), although three recently identified chains, α4(VI), α5(VI), and α6(VI), may replace α3(VI) in some situations. Each chain has a triple helix flanked by N- and C-terminal globular domains that share homology with the von Willebrand factor type A (VWA) domains. During biosynthesis, the three chains come together to form triple helical monomers, which then assemble into dimers and tetramers. Tetramers are secreted from the cell and align end-to-end to form microfibrils. The precise molecular mechanisms responsible for assembly are unclear. Mutations in the three collagen VI genes can disrupt collagen VI biosynthesis and matrix organization and are the cause of the inherited disorders Bethlem myopathy and Ullrich congenital muscular dystrophy. We have identified a Ullrich congenital muscular dystrophy patient with compound heterozygous mutations in α2(VI). The first mutation causes skipping of exon 24, and the mRNA is degraded by nonsense-mediated decay. The second mutation is a two-amino acid deletion in the C1 VWA domain. Recombinant C1 domains containing the deletion are insoluble and retained intracellularly, indicating that the mutation has detrimental effects on domain folding and structure. Despite this, mutant α2(VI) chains retain the ability to associate into monomers, dimers, and tetramers. However, we show that secreted mutant tetramers containing structurally abnormal C1 VWA domains are unable to associate further into microfibrils, directly demonstrating the critical importance of a correctly folded α2(VI) C1 domain in microfibril formation.
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Affiliation(s)
- Leona D Tooley
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia; Departments of Paediatrics, Parkville, Victoria 3052, Australia
| | - Laura K Zamurs
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia
| | - Nicola Beecher
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Naomi L Baker
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia
| | - Rachel A Peat
- Neurogenetics Research Unit, Children's Hospital at Westmead and Discipline of Paediatrics and Child Health, University of Sydney, Westmead, New South Wales 2145, Australia
| | - Naomi E Adams
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia
| | - John F Bateman
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia; Biochemistry and Molecular Biology, University of Melbourne, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Kathryn N North
- Neurogenetics Research Unit, Children's Hospital at Westmead and Discipline of Paediatrics and Child Health, University of Sydney, Westmead, New South Wales 2145, Australia
| | - Clair Baldock
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Shireen R Lamandé
- From the Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia; Departments of Paediatrics, Parkville, Victoria 3052, Australia.
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