Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. jonesj@ent.wustl.edu
During the development of the inner ear, auditory and vestibular ganglion neurons are generated in a highly regulated sequential process. First, neuroblasts are specified, delaminate from the epithelium of the otocyst, and migrate to form the auditory-vestibular ganglion (AVG). These neuroblasts then undergo proliferation and differentiate into afferent neurons of the auditory and vestibular ganglia. The zinc finger transcription factor Gata3 has been shown to play a role in cell proliferation and differentiation in various regions of the inner ear. Here we profile the spatiotemporal expression pattern of Gata3 in the developing auditory and vestibular ganglia of the chick embryo. Gata3 is expressed in a distinct population of sensorineural precursor cells within the otic epithelium, but is not expressed in migrating or proliferating neuroblasts. Following terminal mitosis, Gata3 expression is restricted to very few cells in the auditory ganglion and is not expressed in any cells of the vestibular ganglion. Gata3 expression levels then increase in auditory neurons as they mature. The increase of Gata3 in auditory ganglion neurons is accompanied by decreased expression of NeuroD. Our results suggest that Gata3 may be specifically involved in the differentiation of auditory ganglion neurons.