title: Aquaporin-4 expression in distal myopathy with rimmed vacuoles.
abstract: BACKGROUND
  Distal myopathy with rimmed vacuoles/hereditary inclusion body myopathy is clinically characterized by the early involvement of distal leg muscles. The striking pathological features of the myopathy are muscle fibers with rimmed vacuoles. To date, the role of aquaporin-4 water channel in distal myopathy with rimmed vacuoles/hereditary inclusion body myopathy has not been studied.
  
  
  METHODS
  Here, we studied the expression of aquaporin-4 in muscle fibers of a patient with distal myopathy with rimmed vacuoles/hereditary inclusion body myopathy. Immunohistochemical and immunofluorescence analyses showed that sarcolemmal aquaporin-4 immunoreactivity was reduced in many muscle fibers of the patient. However, the intensity of aquaporin-4 staining was markedly increased at rimmed vacuoles or its surrounding areas and in some muscle fibers. The fast-twitch type 2 fibers were predominantly involved with the strong aquaporin-4-positive rimmed vacuoles and TAR-DNA-binding protein-43 aggregations. Rimmed vacuoles with strong aquaporin-4 expression seen in the distal myopathy with rimmed vacuoles/hereditary inclusion body myopathy patient were not found in control muscles without evidence of neuromuscular disorders and the other disease-controls.
  
  
  CONCLUSIONS
  Aquaporin-4 might be crucial in determining the survival or degeneration of fast-twitch type 2 fibers in distal myopathy with rimmed vacuoles/hereditary inclusion body myopathy.
authors.affiliation: Department of Neurology, Fukushima Medical University, 1, Hikarigaoka, Fukushima 960-1295, Japan. hoshia@fmu.ac.jp
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hoshi
authors.forename: Teiji
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Saeko
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Soeda
authors.forename: Keiko
authors.initials: K
authors.lastname: Shimizu
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ugawa
mesh_terms: D000328:Adult; D051401:Aquaporin 4 / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D049310:Distal Myopathies / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D014018:Tissue Distribution; D014617:Vacuoles / Q000378:metabolism* / Q000473:pathology*
chemical_list: C496030:AQP4 protein, human; D051401:Aquaporin 4; D015415:Biomarkers