Axon guidance during CNS regeneration is required for specific brain innervation

Abstract

Reconstruction of functional neuronal circuits in the mature brain remains a big challenge in the field of central nervous system (CNS) repair. Despite achievement of robust, long-distance regeneration through modulation of specific neuronal intrinsic growth properties, functional recovery is still limited due to major guidance defects of regenerating axons. Using co-activation of mTOR, JAK/STAT and c-myc pathways in retinal ganglion cells (RGC), we highlight that regenerating axons avoid the suprachiasmatic nucleus (SCN) due to repulsive mechanisms. We show that Slit/Robo guidance signaling is responsible for this reinnervation failure. In vivo suppression of this repulsive signaling allows regenerating axons to enter the SCN. The newly formed circuit is associated with functional behavioral recovery. Our results provide evidence that axon guidance mechanisms are required in the context of mature neuronal circuit repair.