Unveiling the cell biology of hippocampal neurons with dendritic axon origin

In mammalian axon-carrying-dendrite (AcD) neurons, the axon emanates from a basal dendrite, instead of the soma, to create a privileged route for action potential generation at the axon initial segment (AIS). However, it is unclear how such unusual morphology is established and whether the structure and function of the AIS in AcD neurons is preserved. By using primary hippocampal neurons as a model, we show that the development of AcD cells can occur independently of the in vivo environment and that a single precursor neurite first gives rise to the axon and then to the AcD. The AIS possesses a similar cytoskeletal architecture as the canonical AIS, and similarly functions as a trafficking barrier to retain axon-specific molecular composition. However, unlike the soma-derived AIS, it does not undergo homeostatic plasticity, contains less cisternal organelles and receives fewer inhibitory inputs. These points of difference may offer insights which cast light on the increased intrinsic excitability of AcD neurons.

Marina Mikhaylova est invitée par Leticia Peris et Yves Goldberg.