title: Proteolysis of beta-dystroglycan in muscular diseases.
abstract: Alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix (ECM), while beta-dystroglycan is a type I integral membrane protein which anchors alpha-dystroglycan to the cell membrane via the N-terminal extracellular domain. The complex composed of alpha-and beta-dystroglycan is called the dystroglycan complex. We reported previously a matrix metalloproteinase (MMP) activity that disrupts the dystroglycan complex by cleaving the extracellular domain of beta-dystroglycan. This MMP creates a characteristic 30 kDa fragment of beta-dystroglycan that is detected by the monoclonal antibody 43DAG/8D5 directed against the C-terminus of beta-dystroglycan. We also reported that the 30 kDa fragment of beta-dystroglycan was increased in the skeletal and cardiac muscles of cardiomyopathic hamsters, the model animals of sarcoglycanopathy, and that this resulted in the disruption of the link between the ECM and cell membrane via the dystroglycan complex. In this study, we investigated the proteolysis of beta-dystroglycan in the biopsied skeletal muscles of various human muscular diseases, including sarcoglycanopathy, Duchenne muscular dystrophy (DMD), Becker muscular dystrophy, Fukuyama congenital muscular dystrophy, Miyoshi myopathy, LGMD2A, facioscapulohumeral muscular dystrophy, myotonic dystrophy and dermatomyositis/polymyositis. We show that the 30 kDa fragment of beta-dystroglycan is increased significantly in sarcoglycanopathy and DMD, but not in the other diseases. We propose that the proteolysis of beta-dystroglycan may contribute to skeletal muscle degeneration by disrupting the link between the ECM and cell membrane in sarcoglycanopathy and DMD.
authors.affiliation: Department of Neurology and Neuroscience, Teikyo University School of Medicine,2-11-1 Kaga Itabashi-ku, Tokyo 173-8605, Japan. k-matsu@med.teikyo-u.ac.jp
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Matsumura
authors.forename: Di
authors.initials: D
authors.lastname: Zhong
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Saito
authors.forename: Ken
authors.initials: K
authors.lastname: Arai
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Adachi
authors.forename: Hisaomi
authors.initials: H
authors.lastname: Kawai
authors.forename: Itsuro
authors.initials: I
authors.lastname: Higuchi
authors.forename: Ichizo
authors.initials: I
authors.lastname: Nishino
authors.forename: Teruo
authors.initials: T
authors.lastname: Shimizu
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D002648:Child; D002675:Child, Preschool; D049030:Dystroglycans / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009135:Muscular Diseases / Q000145:classification / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: C483081:DAG1 protein, human; D049030:Dystroglycans