Axotomy induces axonogenesis in hippocampal neurons by a mechanism dependent on importin β

We characterize the previously unrecognized phenomenon of axotomy-induced axonogenesis in rat embryonic hippocampal neurons in vitro and elucidate the underlying mechanism. New neurites arose from cell bodies after axotomy and grew. These neurites were Tau-1-positive, and the injured axons showed negative immunoreactivity for Tau-1. Axonogenesis was delayed in these neurons by inhibiting the dynein-dynactin complex through the overexpression of p50. Importin beta, which was locally translated after axotomy, was associated with the dynein-importin a complex and was required for axonogenesis. Taken together, these results suggest that retrograde transport of injury-induced signals in injured axons play key roles in the axotomy-induced axonogenesis of hippocampal neurons. (C) 2011 Elsevier Inc. All rights reserved.