SRS46 - The initiation of vertebrate peripheral neuron regeneration is controlled by microtubule nucleation from the somatic Golgi apparatus

Abstract Axon regeneration following peripheral nerve injury involves extensive reorganisation of the microtubule network, which is essential for restoring neuronal structure and function. However, the mechanisms underlying de novo microtubule nucleation during this regenerative process remain poorly understood, particularly given that adult neurons lack an active centrosome to function as the microtubule-organising centre (MTOC). Studies in embryonic Drosophila neurons have implicated the Golgi apparatus as an MTOC but evidence is lacking in an adult mammalian neurons. We therefore hypothesised that the Golgi serves as the primary MTOC during peripheral axon regeneration. To investigate this, we employed a combination of high-resolution live-cell and fixed imaging techniques across in vitro and in vivo adult rat models and in vitro human neuronal cultures. Our findings reveal significant morphological changes in Golgi structure in response to injury, involving initial fragmentation followed by re-compaction. Importantly, this re-compaction coincides with the emergence of de novo microtubules from the Golgi and the onset of axon regeneration. These structural changes are accompanied by the dynamic localisation of the key microtubule nucleation factors AKAP9 and γ-tubulin to the Golgi. Crucially, disruption of Golgi structure or AKAP9 function impairs the localisation of γ-tubulin to the Golgi, halts Golgi-mediated microtubule nucleation, and ultimately inhibits axonal regeneration. Together, these results identify the Golgi as a central hub for microtubule nucleation and significantly advance our understanding of the intracellular processes governing peripheral neuronal regeneration. This work highlights the Golgi as a promising target for therapeutic strategies aimed at enhancing recovery following peripheral nerve injury.