MICROTUBULE-ASSOCIATED PROTEIN-TAU EPITOPES ARE PRESENT IN FIBER LESIONS IN DIVERSE MUSCLE DISORDERS

The microtubule-associated protein tau is a major cytoskeletal protein involved in the neurofibrillary tangles of Alzheimer's disease. Altho ugh tau is predominantly a neuronal protein, it has been demonstrated in glia and other nonneuronal cells. We describe the presence of micro tubule-associated protein tau epitopes in various muscle fiber lesions in oculopharyngeal and Becker muscular dystrophy, dermatomyositis, ce ntral core disease, neurogenic atrophy, and in the recovery phase of a n attack of malignant hyperthermia. Western blot demonstrated a 100- t o 110-kd tau-immunoreactive protein probably corresponding to 'big tau ' as described in peripheral nerves. Tau immunoreactivity in muscle fi ber lesions usually co-localized with tubulin, although electron micro scopy failed to show an increase in microtubules. Tau and tubulin reac tivity also correlated with the presence of desmin and vimentin epitop es. Possible explanations for the presence of tau are briefly discusse d.