Reciprocal interactions of Fgf10/Fgfr2b modulate the mouse tongue epithelial differentiation

The molecular mechanisms for epithelial differentiation have been studied by observing skin development in embryogenesis, but the early signaling modulations involved in tongue epithelial differentiation are not completely understood. Based on the gene expression patterns of the Fgf signaling molecules and previous results from Fgf10 and Fgfr2b knockout mice, it was hypothesized that there would be fundamental signaling interactions through the epithelial Fgfr2b and its mesenchymal ligand Fgf10 to regulate tongue epithelium differentiation. To elucidate these reciprocal interactions in tongue epithelial differentiation, this study employed an in vitro tongue organ culture system with antisense-oligodeoxynucleotides (AS-ODNs) and recombinant protein-soaked bead implantation for the loss-of-function and gain-of-function studies. Functional analysis of Fgf signaling revealed precise reciprocal interactions, which showed that mesenchymal Fgf10 rather than Fgf7 modulates tongue epithelial differentiation via Fgfr2b in a temporal- and spatial-specific manner.