Nature of "Tau" immunoreactivity in normal myonuclei and inclusion body myositis.
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.
Salajegheh
Mohammad
M
Department of Neurology, Division of Neuromuscular Disease, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Pinkus
Jack L
JL
Nazareno
Remedios
R
Amato
Anthony A
AA
Parker
Kenneth C
KC
Greenberg
Steven A
SA
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*
D000906:Antibodies; D016875:tau Proteins