OKADAIC ACID MODULATES THE CYTOSKELETON CHANGES INDUCED BY AMYLOID PEPTIDE-(25-35) IN CULTURED ASTROCYTES

AMYLOID beta-protein (25-35) (beta A) induced a marked morphological c hange in astrocytes, changing their flat polygonal shape into a stella te process-bearing morphology. The changes induced by beta A were conc entration and time-dependent, whereas the addition of a scrambled pept ide did not alter astrocyte morphology. We discard the possibility of beta A-astrocytes being type II-like astrocytes. We also analysed the influence of the presence of kinase and phosphate inhibitors on this m orphological change. Our data indicate that the beta A-induced phenoty pe was not affected by the inhibition of protein tyrosine kinase or ty rosine phosphatases. Only the addition of okadaic acid to astrocytes p revented the morphological transformation from flat to stellate shape, induced by beta A (25-35). Inhibition of the stellate phenotype by ok adaic acid was initiated at a concentration of 10 nM which suggested t hat either phosphatase 2A or 1 plays an important role in the beta A a strocytic transformation.