CYTOSKELETAL PLASTICITY IN CELLS EXPRESSING NEURONAL MICROTUBULE-ASSOCIATED PROTEINS

MAP2 and tau are the two most prominent neuron-specific microtubule-as sociated proteins. They have been implicated in the stabilization of m icrotubules and consequently of neurite morphology. To investigate the ir influence on microtubule dynamics, we have tagged both proteins wit h green fluorescent protein and expressed them in non-neuronal cells. Time-lapse recordings of living cells showed that MAP2 and tau did not significantly affect the rates of microtubule growth and shrinkage. L onger recordings revealed the growth and disappearance of MAP-induced microtubule bundles coinciding with changes in cell shape. This suppor ts the idea that microtubule dynamics are influenced by the cortical c ytoskeleton. The dynamics-preserving stabilization of microtubules by MAP2 and tau thus provides a molecular basis for the morphological pla sticity reported to exist in established neurites.