The sensory and supporting cells of the organ of Corti are derived from a limited number of progenitors. The mechanisms that regulate the number of sensory progenitors are not known. Here, we show that Fibroblast Growth Factors (FGF) 9 and 20, which are expressed in the non-sensory (Fgf9) and sensory (Fgf20) epithelium during otic development, regulate the number of cochlear progenitors. We further demonstrate that Fgf receptor (Fgfr) 1 signaling within the developing sensory epithelium is required for the differentiation of outer hair cells and supporting cells, while mesenchymal FGFRs regulate the size of the sensory progenitor population and the overall cochlear length. In addition, ectopic FGFR activation in mesenchyme was sufficient to increase sensory progenitor proliferation and cochlear length. These data define a feedback mechanism, originating from epithelial FGF ligands and mediated through periotic mesenchyme that controls the number of sensory progenitors and the length of the cochlea.
Animal experimentation: This study was carried out in strict accordance with the recommendations in the Guide for the Careand Use of Laboratory Animals of the National Institutes of Health. The protocol was approved by theWashington University Division of Comparative Medicine Animal Studies Committee (Protocol Number20130201). All efforts were made to minimize animal suffering.
- Tanya T Whitfield, University of Sheffield, United Kingdom
© 2015, Huh et al.
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