Abstract
Microtubules form polarised arrays throughout axons and dendrites necessary for neuronal growth and maintenance. γ-tubulin-ring-complexes (γ-TuRCs) nucleate microtubules at microtubule organising centres (MTOCs), but how microtubules are generated and organised within neurons remains unclear. We show that γ-TuRCs are predominantly recruited to the somatic Golgi, rather than to dendritic Golgi outposts, within Drosophila neurons. Microtubules nucleated from the somatic Golgi grow preferentially towards and into the axon, while growing microtubules that approach dendrites are excluded. Both directed growth and dendritic exclusion depend upon Kinesin-2, which associates with plus ends and directs their growth towards the plus ends of adjacent microtubules. We propose that plus-end-associated Kinesin-2 guides growing microtubules nucleated from the somatic Golgi towards the axon and prevents plus end entry into dendrites when engaging with oppositely polarised microtubules. In summary, microtubules are nucleated from the somatic Golgi within neurons and their guidance is necessary to maintain neuronal microtubule polarity.