MODULATION OF PHOSPHORYLATION OF NEURONAL CYTOSKELETAL PROTEINS BY NEURONAL DEPOLARIZATION

1, The neuronal cytoskeletal protein tau and the carboxy tails of cyto skeletal proteins neurofilament-M (NF-M) and neurofilament-H (NF-H) ar e phosphorylated on serine residues by the cyclin-dependent kinase cdk -5. 2, In aggregating neuronal-glial cultures we show that veratridine -mediated cation influx causes dephosphorylation of tau, NF-M and NF-H . Dephosphorylation blocked specifically by cyclosporine A but not by okadiac acid at concentrations up to 200 nM. 3. These results suggest that veratridine-triggered cation influx causes activation of PP-2B (c alcineurin) leading to dephosphorylation of these cytoskeletal protein s.