Roles of ß-catenin in inner ear development in rat embryos

Abstract 

We studied the roles of ß-catenin in inner ear development in rat embryos using immunostaining and antisense experiments. High levels of ß-catenin appeared transiently in the otic cup during inner ear development. While ß-catenin accumulation was not yet observed in the thickened surface ectoderm at the otic placode, it became to be detected at the apical surface of the otic cup. Then it disappeared from the otocyst. When embryos were treated with the ß-catenin antisense oligodeoxynucleotide (ODN), accumulation of ß-catenin in the otic cup was suppressed and the ß-catenin protein level was significantly less in treated embryos than in controls. The number of cells in the otic cup in treated embryos was smaller than in control embryos. Cells that incorporated bromodeoxyuridine (BrdU) in the otic placode were fewer in number in treated embryos than in controls. In control embryos, acoustic neurons were detected by 2H3 (anti-neurofilament 165 kDa antibody) staining within the acoustic neural crest complex, while only a little staining of 2H3 was observed in the complex of the treated embryos. These results suggested that ß-catenin plays a role in cell proliferation in the otic placodes and in differentiation of acoustic neurons within the acoustic neural crest complex.