Ebf1 is a mouse deafness gene and deletion causes a dramatic increase in hair cells and support cells of the organ of Corti

Following up on our previous observation that early B cell factor (EBF) sites are enriched in open chromatin of the developing sensory epithelium of the mouse cochlea, we investigated the effect of deletion of Ebf1 on inner ear development. We used a Cre driver to delete Ebf1 at the otocyst stage prior to development of the cochlea. These animals survived and were fertile. We examined the cochlea at postnatal day (P) 1 and found that the sensory epithelium had doubled in size but the length of the cochlear duct was unaffected. We also found that deletion of Ebf1 led to ectopic sensory patches in the Kölliker's organ. Innervation of the developing organ of Corti was disrupted with no obvious spiral bundles. The ectopic patches were also innervated. All the extra hair cells (HCs) within the sensory epithelium and Kölliker's organ contained mechanoelectrical transduction channels as indicated by rapid uptake of FM1-43. The excessive numbers of HCs were still present in the adult Ebf1 conditional knockout (cKO) animal. The animals had no detectable auditory brainstem response (ABR) suggesting that this gene is essential for hearing development. Overall design: Sox2-GFP cells were Facs purified from mouse cochlear ducts at E12.5, E14.5 and E16.5. The cells were then made into single cells sequencing libraries using 10X genomics protocol