Analysis of FGF20-regulated genes in organ of Corti progenitors by translating ribosome affinity purification

Abstract

ABSTRACTBackgroundUnderstanding the mechanisms that regulate hair cell (HC) differentiation in the organ of Corti (OC) is essential to designing genetic therapies for hearing loss due to HC loss or damage. We have previously identified Fibroblast Growth Factor 20 (FGF20) as having a key role in HC and supporting cell differentiation in the mouse OC. To investigate the genetic landscape regulated by FGF20 signaling in OC progenitors, we employ Translating Ribosome Affinity Purification combined with Next Generation mRNA Sequencing (TRAPseq) in the Fgf20 lineage.ResultsWe show that TRAPseq targeting OC progenitors effectively enriched for mRNA within this rare cell population. TRAPseq identified differentially expressed genes downstream of FGF20, including Etv4, Etv5, Etv1, Dusp6, Hey1, Hey2, Heyl, Tectb, Fat3, Cpxm2, Sall1, Sall3, and cell cycle regulators such as Cdc20. Analysis of Cdc20 conditional-null mice identified decreased cochlea length, while analysis of Sall1-ΔZn2-10 mice, which harbor a mutation that causes Townes-Brocks syndrome, identified a decrease in outer hair cell number.ConclusionsWe present two datasets: genes with enriched expression in OC progenitors, and genes regulated by FGF20 in the embryonic day 14.5 cochlea. We validate select differentially expressed genes via in situ hybridization and in vivo functional studies in mice.Key findingsTranslating Ribosome Affinity Purification (TRAP) with Fgf20-Cre enriches for prosensory cell mRNATRAP combined with RNAseq identifies genes downstream of FGF20 during prosensory cell differentiationFGF20 regulates Sall1, gene implicated in human sensorineural hearing lossGrant Sponsor and NumberNational Institute on Deafness and Other Communication Disorders – DC017042 (DMO) Washington University Institute of Clinical and Translational Sciences and National Center for Advancing Translational Sciences – CTSA grant UL1TR002345 (JIT471 to DMO) March of Dimes – 6-FY13-127 (MR)