title: Strong immunoreactivity of cathepsin L at the site of rimmed vacuoles in diseased muscles.
abstract: Skeletal muscle samples from four patients with myopathies showing autophagic vacuole formation were examined by immunohistochemical, biochemical and immunoblot analyses. Immunochemical studies demonstrated strongly positive reactions of cathepsins B and L in and around the rimmed vacuoles and weak reactions in intramyofibral portions of degenerating muscle fibres. Faint staining of cathepsin H was also seen at the sites of rimmed vacuoles. Biochemical analyses showed increased activity of cathepsin B and L in muscle specimens from the patients with rimmed vacuole formation. However, there was no remarkable cathepsin H activity in the muscle specimens from these patients. Cathepsin L immunoblot analysis of muscle extracts showed three bands with molecular masses of 30 kDa, 36 kDa and 39 kDa. The immunostaining of cathepsin L from patients with rimmed vacuole formation was stronger than that of normal controls. Cathepsin B immunoblot analysis showed only faint bands in samples from patients with rimmed vacuole formation and normal controls. This study demonstrated, for the first time, strong immunoreactivity of cathepsin L at the sites of rimmed vacuoles. Possible mechanisms of rimmed vacuole formation are discussed.
authors.affiliation: Department of Medicine, Showa University Fujigaoka Hospital, Yokahama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Jimi
authors.forename: Y
authors.initials: Y
authors.lastname: Satoh
authors.forename: A
authors.initials: A
authors.lastname: Takeda
authors.forename: S
authors.initials: S
authors.lastname: Shibuya
authors.forename: Y
authors.initials: Y
authors.lastname: Wakayama
authors.forename: K
authors.initials: K
authors.lastname: Sugita
mesh_terms: D000328:Adult; D000368:Aged; D056668:Cathepsin L; D002403:Cathepsins / Q000032:analysis*; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000378:metabolism*; D014617:Vacuoles
chemical_list: D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L