Trafficking of polarized membrane proteins in developing and mature hippocampal neurons

This dissertation investigates two mechanisms of neuronal protein trafficking using live‑cell imaging of GFP‑tagged cargos in cultured hippocampal neurons. First, it demonstrates that dendritic proteins are restricted from the axon by a dual gate: selective entry, which lowers the probability that dendritic vesicles enter the axon, and a transport filter in the proximal axon that halts those that do. The filter aligns with the axon initial segment in mature neurons but is detectable before initial segment formation, and selective dendritic transport is dynamically regulated in earlier neurites. Second, synaptic vesicle, dense‑core granule, and axonal plasma‑membrane proteins initially co‑traffic in a common post‑Golgi transport tubule; subsequently, specialized vesicles emerge, with KIF1A associating later with dense‑core granule–containing organelles. These findings reveal developmental and compartment‑specific controls that coordinate dendritic restriction and long‑range axonal delivery.