Specification of Sensory Fates in the Vertebrate Inner Ear

Abstract

The otic placode gives rise to the inner sensory organs subserving hearing and balance, along with the associated auditory and vestibular ganglion neurons that supply their afferent innervation. Our lab is using both chicken and zebrafish to study the molecular basis of cell fate specification within the otic neurosensory lineages. In chicken embryos, Wnt/β-catenin signaling can promote vestibular over auditory sensory organ fates at early stages if the pathway is manipulated by retrovirus-mediated overexpression. As the organs begin to differentiate into hair cells and supporting cells, the miR-183 family of microRNAs can control the number of HCs that form in the zebrafish, as shown by gene knockdown and overexpression. We are currently studying whether these microRNAs play a similar role in the chicken ear. Somewhat later in development, Wnt overexpression can influence the differentiation of distinct hair cell types (tall vs. short) in the auditory sensory organ of the bird. These findings may offer therapeutic strategies to induce the regeneration of supporting cells into the appropriate types of hair cells in animal models of deafness.