title: Nature of "Tau" immunoreactivity in normal myonuclei and inclusion body myositis.
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.
authors.affiliation: Department of Neurology, Division of Neuromuscular Disease, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Salajegheh
authors.forename: Jack L
authors.initials: JL
authors.lastname: Pinkus
authors.forename: Remedios
authors.initials: R
authors.lastname: Nazareno
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Amato
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Parker
authors.forename: Steven A
authors.initials: SA
authors.lastname: Greenberg
mesh_terms: D000906:Antibodies / Q000737:chemistry; D000918:Antibody Specificity; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D003429:Cross Reactions; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D042282:Microdissection; D032342:Muscle Cells / Q000378:metabolism* / Q000473:pathology; D018979:Myositis, Inclusion Body / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000473:pathology; D016875:tau Proteins / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D016875:tau Proteins