title: Expression of myoferlin in skeletal muscles of patients with dysferlinopathy.
abstract: Myoferlin is a novel protein of unknown function with high homology to dysferlin, the gene mutations of which cause limb girdle muscular dystrophy type 2B and Miyoshi myopathy. The myoferlin gene seems to be a candidate for the modifier, and because of the high homology to dysferlin myoferlin may work as a compensator for the absence of dysferlin in dysferlinopathy. This hypothesis is based on the observation that utrophin, which has 80% homology with dystrophin, is overexpressing in the dystrophin deficient myofibers. To test this hypothesis, we investigated the myoferlin expression by immunoblot and immunohistochemical analysis in muscles of five patients with dysferlinopathy. For this aim, we generated a myoferlin specific antibody that does not cross react with dysferlin, and performed the immunoblot, immunohistochemical and immunoelectron microscopic studies. Immunohistochemical analysis showed that the antibodies against myoferlin and dysferlin clearly stained the normal human myofiber surface membranes. The electron microscopy of single immunogold labeled samples for myoferlin showed the presence of the molecular signal along the normal muscle cell membrane. Immunoblot analysis showed that the intensity of 230-kDa myoferlin band of dysferlinopathy muscle extracts was similar to that of normal muscle extracts. The immunostaining of dysferlinopathy muscles with anti-myoferlin antibody revealed a weak immunoreactivity along the muscle cell surface. Thus, the compensatory overexpression of myoferlin was not detected in muscles with dysferlinopathy.
authors.affiliation: Department of Neurology, Showa University Fujigaoka Hospital, 1-30 Fujigaoka, Yokohama 227-8501, Japan. yukacrystal@yahoo.co.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Inoue
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Wakayama
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kojima
authors.forename: Seiji
authors.initials: S
authors.lastname: Shibuya
authors.forename: Takahiro
authors.initials: T
authors.lastname: Jimi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Oniki
authors.forename: Ichizo
authors.initials: I
authors.lastname: Nishino
authors.forename: Ikuya
authors.initials: I
authors.lastname: Nonaka
mesh_terms: D001706:Biopsy; D002135:Calcium-Binding Proteins; D000073939:Dysferlin; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D009124:Muscle Proteins / Q000378:metabolism*; D009136:Muscular Dystrophies / Q000378:metabolism* / Q000473:pathology; D052097:Quadriceps Muscle / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure
chemical_list: D002135:Calcium-Binding Proteins; C114839:DYSF protein, human; D000073939:Dysferlin; C415584:MYOF protein, human; D008565:Membrane Proteins; D009124:Muscle Proteins