Intracellular accumulation and reduced sarcolemmal expression of dysferlin in limb–girdle muscular dystrophies

Authors

  • Federica Piccolo PhD,

    1. Howard Hughes Medical Institute, Department of Physiology and Biophysics and Department of Neurology, University of Iowa College of Medicine, Iowa City, IA
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  • Steven A. Moore MD, PhD,

    1. Department of Pathology, University of Iowa College of Medicine, Iowa City, IA
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  • Gwendolyn C. Ford MD,

    1. Howard Hughes Medical Institute, Department of Physiology and Biophysics and Department of Neurology, University of Iowa College of Medicine, Iowa City, IA
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  • Kevin P. Campbell PhD

    Corresponding author
    1. Howard Hughes Medical Institute, Department of Physiology and Biophysics and Department of Neurology, University of Iowa College of Medicine, Iowa City, IA
    • Howard Hughes Medical Institute, University of Iowa College of Medicine, 400 EMRB, Iowa City, IA 52242
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Abstract

Dysferlin has recently been identified as a novel gene involved in limb–girdle muscular dystrophy type 2B (LGMD2B) and its allelic disease, Miyoshi myopathy. The predicted structure of dysferlin suggests that it is a transmembrane protein possibly involved in membrane fusion. Thus, unlike previously identified structural proteins in muscular dystrophy, dysferlin is likely involved in a novel pathogenic mechanism for this disease. In this study, we have analyzed the expression of dysferlin in skeletal muscle of patients with disruptions in the dystrophin–glycoprotein complex and patients with a clinical diagnosis of LGMD2B or Miyoshi myopathy. We show expression of dysferlin at the sarcolemma in normal muscle and reduced sarcolemmal expression along with accumulation of intracellular staining in dystrophic muscle. Electron microscopy in Miyoshi myopathy biopsies suggests that the cytoplasmic staining could be a result of the abundance of intracellular vesicles. Our results indicate that dysferlin expression is perturbed in LGMD and that both mutations in the dysferlin gene and disruption of the dystrophin–glycoprotein complex can lead to the accumulation of dysferlin within the cytoplasm. Ann Neurol 2000;48:902–912

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