CRMP-5 interacts with tubulin to promote growth cone development in neurons.

Collapsin response mediator proteins (CRMPs) have been reported to control axonal guidance during neuronal development and degeneration. Among these proteins, CRMP-5 has been indicated to play an important role in growth cone development. However, the mechanisms underlying the linkage between growth cone development and the cytoskeleton remain to be elucidated. Here, we report that CRMP-5 interacts with tubulin to mediate growth cone development in cultured hippocampal neurons. We found that CRMP-5 physically interacted with tubulin in the growth cones of developing neurons. CRMP-5 colocalized with tubulin in lamellipodia in HEK293 cells and in the growth cones of cultured hippocampal neurons. Genetic silencing of CRMP-5 using RNA interference led to abnormal growth cone morphology in neurons. Overexpression of CRMP-5 led to significantly increased filopodial formation and enlarged growth cones. These results suggest that CRMP-5 interacts with tubulin to regulate growth cone dynamics, thus complying with the restrictive intracellular guidance cues.