Fig. 4: Tbx2 maintains IHC and ISC fate by preventing transdifferentiation into OHCs and OSCs, respectively.
From: TBX2 specifies and maintains inner hair and supporting cell fate in the Organ of Corti
a–d Hair and supporting cell differentiation in mice in which Tbx2 was ablated (Sox2-Tbx2LOF) in SOX2+ cells in the organ of Corti by tamoxifen administration at E16.5. a, b (Co-)immunofluorescence analysis of IHC and OHC differentiation in E18.5 whole cochleae by antibodies against MYO6 (all hair cells), BCL11B (OHCs), SLC17A8 (IHCs). Red arrow points to a MYO6+/SLC17A8+ IHC, green arrow to a MYO6+/BCL11B+ OHC-like and blue arrow to a double-negative hair cell (SLC17A8-/BCL11B-) in the innermost hair cell row (a). b Quantification of hair cell types in the inner compartment. Mean±standard deviation, two-sided unpaired t-test with Welch’s correction or Mann-Whitney-U test. **p < 0.01; ***p < 0.001; ****p < 0.0001. n = 11 for each genotype. c (Co-)immunofluorescence analysis of supporting cell differentiation in E18.5 cochleae by antibodies against MYO7A/MYO6 (all hair cells), NGFR (pillar cells (PCs)), S100A1 (Deiters’ cells (DCs) and IHCs), PROX1 (DCs and PCs), SOX2 (all supporting cells) and of compartmentalization by antibodies against CDH1 in the outer compartment (OC) and CDH2 in the inner compartment (IC). Nuclei were counterstained with DAPI. Arrows points to gaps in the shifted and irregular row of NGFR+ pillar cells. n = 6 for each genotype. d List of genes with increased expression in E18.5 Sox2-Tbx2LOF organs of Corti as detected by microarray analysis (n = 4). FC, fold change. e Validation of selected microarray candidates by RNA in situ hybridization analysis. Insm2 expression is shown at the basal and medial (mid) turn of the cochlear duct. Dotted circles mark the nuclei of hair cells. Arrow points to the innermost hair cell. n = 3 for each genotype. f Histological analysis (first row) and immunofluorescence (second and third row) of hair cell markers at P21: MYO7A (all hair cells), KCNQ4 and IKZF2 (OHCs), CALB2 and TBX2 (IHCs). n = 5 for each genotype. g Analysis of hair cell innervation by CALB2 immunofluorescence at the apical level of the organ of Corti of P21 control and Sox2-Tbx2LOF mice. CALB2 marks type I afferent fibers, IHCs (strong) and OHCs (weak). n = 5 for each genotype. Scale bars: 30 µm. LER lesser epithelial ridge, GER greater epithelial ridge. The exact p-values and related source data are provided as a Source Data file.
