HYPERPHOSPHORYLATED TAU PROTEINS DIFFERENTIATE CORTICOBASAL DEGENERATION AND PICKS-DISEASE

In neurodegenerative disorders, hyperphosphorylated tau proteins aggre gate into abnormal filaments. In the present study, tau protein altera tions were studied in one corticobasal degeneration and seven Pick's d isease cases using specific immunological probes. The typical lesions of corticobasal degeneration and Pick's disease were revealed by immun ohistochemistry, including the presence of Pick bodies and achromatic swollen neurons, neuritic alterations, and neurofibrillary tangles. Ta u-immunoreactive glial tangles were also observed. By immunoblotting, the case of corticobasal degeneration was characterized by the tau pro file previously reported to occur in progressive supranuclear palsy wi th an intense labeling of the two tau 64 and 69 bands, while tau 55 wa s not visualized. In Pick's disease cases with Pick bodies and neurofi brillary tangles, a tau tripler similar to that encountered in Alzheim er's disease (tau 55, 64 and 69) was detected. Furthermore, a particul ar tau profile was found in four Pick's disease cases showing only Pic k bodies and no neurofibrillary tangles. In these cases, tau 55 and 64 were strongly immunoreactive, whereas tau 69 was almost unlabeled. Th ese differences are likely to be related to particular pools of tau is oforms present within the degenerating neurons. Since there is a great diversity of neurodegenerative disorders with substantial clinical an d neuropathological overlap, the electrophoretic profile of tau protei ns could represent a useful marker for the type of neurodegeneration.