Microtubule-based transport along axons, dendrites and axonemes

MTs in cytoplasmic extensions including axons, dendrites and axonemes serve as polarized tracks for vectorial intracellular transport driven by MT-based motor proteins. Although axons and axonemes serve very different functions, increasing evidence suggests that the transport events, MT organization and the motors involved in their formation and function are conserved. Thus, there are obvious similarities in the mechanisms of axonal transport and IFT. The MT arrays of axons and axonemes are parallel, whereas those of dendrites are anti-parallel, but the functional significance of this difference and its consequences for mechanisms of transport along these processes are unclear. MT-based motor proteins of the dynein and kinesin superfamilies transport a variety of cargos including membrane-bound vesicles and macromolecular complexes along MTs of axons, dendrites and axonemes, and thus contribute to the formation, maintenance and function of these cytoplasmic extensions. Chemosensory neurons in the nematode C. elegans represent an appealing system for studying transport events along dendrites and axonemes that occur sequentially in a single cell.