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 change in astrocytes, changing their flat polygonal shape into a stellate process-bearing morphology. The changes induced by beta A were concentration and time-dependent, whereas the addition of a scrambled peptide 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 morphological change. Our data indicate that the beta A-induced phenotype was not affected by the inhibition of protein tyrosine kinase or tyrosine phosphatases. Only the addition of okadaic acid to astrocytes prevented the morphological transformation from flat to stellate shape, induced by beta A (25-35). Inhibition of the stellate phenotype by okadaic acid was initiated at a concentration of 10 nM which suggested that either phosphatase 2A or 1 plays an important role in the beta A astrocytic transformation.