More than just supporting: new insights into the roles of supporting cells in the postnatal and adult inner ear

GOMEZ CASATI, ME

Congreso; Sociedad Argentina de Neurociencias; 2011

Despite that all inner ear hair cells and their associated sensory nerve terminals are surrounded by supporting cells (SCs), the roles of these non-neuronal cells in the postnatal period remain poorly understood. Recent evidence indicates that SCs have many glia-like characteristics, including expression of erbB receptors. We are using genetically modified mice to investigate the roles of inner ear SCs. Our studies show that SCs are critical for the formation and maintenance of vestibular and cochlear inner hair cell synapses and for the long-term survival of spiral ganglion neurons. We show that BDNF produced by SCs is critical for synapse formation/maintenance in the vestibular system, while supporting cell-derived NT3 plays similar roles in the cochlea. Expression of BDNF and NT3 is regulated by the NRG1/ErbB signaling pathway, pointing to reciprocal trophic interactions between sensory neurons and SCs in the formation and maintenance of a functional sensory epithelium. Together, these studies indicate that SCs are actively engaged in the promotion of maturation, function and maintenance of the inner ear and that this is, at least in part, mediated by reciprocal signals between sensory neurons and SCs involving NRG1-erbB and BDNF-TrkB/ NT3-TrkC signaling.