Nature of "Tau" immunoreactivity in normal myonuclei and inclusion body myositis

Muscle Nerve. 2009 Oct;40(4):520-8. doi: 10.1002/mus.21471.

Abstract

Sarcoplasmic accumulation of phosphorylated-tau has been widely stated to occur in and contribute to the pathogenesis of muscle disease in inclusion body myositis. Twenty inflammatory myopathy and 10 normal muscle samples along with a range of other tissues were stained with anti-"tau" antibodies (tau-5, pS422, and SMI-31). Myonuclear and sarcoplasmic fractions were prepared using differential solubilization and laser-capture microdissection, and immunoblots were performed using pS422 and SMI-31 antibodies. All three antibodies demonstrated anti-tau immunoreactivity in myonuclei from normal and diseased muscle, but not in nuclei from other tissues. Western blots showed pS422 and SMI-31 immunoreactivity against nuclear proteins outside the region expected for phosphorylated-tau. Antibodies previously reported to indicate abnormal accumulation of phosphorylated-tau in IBM myofibers react to normal myonuclei and recognize proteins other than tau. Normal myonuclei contain neurofilament H or other unidentified 200 kDa proteins with similar phosphorylated motifs accounting for SMI-31 immunoreactivity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies / chemistry
  • Antibody Specificity
  • Blotting, Western
  • Cell Nucleus / metabolism*
  • Cell Nucleus / pathology
  • Cross Reactions
  • Fluorescent Antibody Technique
  • Humans
  • Immunohistochemistry
  • Microdissection
  • Muscle Cells / metabolism*
  • Muscle Cells / pathology
  • Myositis, Inclusion Body / metabolism*
  • Myositis, Inclusion Body / pathology
  • Phosphorylation
  • Sarcoplasmic Reticulum / metabolism
  • Sarcoplasmic Reticulum / pathology
  • tau Proteins / immunology
  • tau Proteins / metabolism*

Substances

  • Antibodies
  • tau Proteins