ABSTRACT: The inner ear utilizes sensory hair cells as mechano-electric transducers for sensing sound and balance. In mammals, these sensory hair cells lack the capacity for regeneration and if damaged lead to hearing or balance disorders. However, non-mammalian vertebrates such as birds maintain their regenerative abilities throughout their life. In a previous study we conducted a gene expression profiling time course of regenerating sensory epithelia (SE) in avian cochlea and utricle on a custom transcription factor microarray following damage by both laser and chemical ablation. We identified several known signaling cascades such as The Pax-Eya-Six-Dach pathway, Ap-1 pathway, the Tgf-β pathway and sonic hedgehog signaling that are differentially expressed during SE regeneration. In this study we selected 27 of these genes for knockdown by siRNA or small molecule inhibition to determine their requirement for SE regeneration and identify downstream targets. We assessed phenotypes using a 96 well proliferation assay and expression profiled each knockdown on a custom transcription factor microarray. Using these techniques we have determined several genes that are required for SE proliferation and identified novel epistatic relationships between many of these genes. Pure sensory epithelia was isolated from avian utricles. Sensory epithelia was physically dissociated and grown in 96 well cultures for 3 days. Prior to confluency, dissociated sensory epithelia were transfected with siRNAs (12 pmol/well) or small molecule inhibitor in 0.1% DMSO. RNA was isolated 24 hrs post transfection and assayed on a custom oligonucleotide transcription factor microarray compared to controls (GFP siRNA or 0.1% DMSO only). siRNA: CEBPG, JunD, BTAF1, LRP5, PAX2, PAX5, PAX7, Wnt4, BCL11A, CBX3, CBX4, CTNNB1, CUTL1, MYT1L, RARA, TIMELESS, TRIP15, PAX3, EZH2, HES1, ID1, CDKN1B, and PPARGC1 small molecule inhibition: IGF, MAPK, SHH, and JNK
