p27Kip1 Modulates Axonal Transport by Regulating α-Tubulin Acetyltransferase 1 Stability

The protein p27 Kip1 plays roles that extend beyond cell-cycle regulation during cerebral cortex development, such as the regulation of neuronal migration and neurite branching via signaling pathways that converge on the actin and microtubule cytoskeletons. Microtubule-dependent transport is essential for the maturation of neurons and the establishment of neuronal connectivity though synapse formation and maintenance. Here, we show that p27 Kip1 controls the transport of vesicles and organelles along the axon of mice cortical projection neurons in vitro . Moreover, suppression of the p27 Kip1 ortholog, dacapo , in Drosophila melanogaster disrupts axonal transport in vivo , leading to the reduction of locomotor activity in third instar larvae and adult flies. At the molecular level, p27 Kip1 stabilizes the α-tubulin acetyltransferase 1, thereby promoting the acetylation of microtubules, a post-translational modification required for proper axonal transport.