E-Cadherin Can Replace N-Cadherin during Secretory-Stage Enamel Development - Figure 1

<p>(<b>a</b>) qPCR analysis of N-cadherin gene expression in wild-type (WT) and N-cadherin conditional knockout (cKO) mouse enamel organs. mRNA was extracted from postnatal day-5 enamel organs from 3 mice per genotype for qPCR analysis. Results are presented as expression ratios relative to the WT levels. The ablated N-cadherin cKO enamel organs (K14-<i>Cre</i>-N-cadherin-<i>LoxP</i>+/+) had 0.19 fold of the WT N-cadherin expression level (***, p<0.001) and the heterozygous ablated mice (K14-<i>Cre</i>-N-cadherin-<i>LoxP</i>+/−) had 0.75 fold of the WT expression level (*, p<0.05). (<b>b</b>) N-cadherin protein expression was ablated in the ameloblast layer of K14-<i>Cre</i>-N-cadherin-<i>LoxP</i>+/+ mice. Immunohistochemical staining of N-cadherin was performed on paraffin-imbedded incisor sections from both WT and N-cadherin cKO mice. In WT mice N-cadherin was not expressed highly in pre-secretory stage ameloblasts, but was strongly up-regulated during the secretory stage and was later down-regulated when the ameloblasts progressed into the maturation stage. In contrast, regardless of developmental stage, N-cadherin expression was not observed in the N-cadherin cKO ameloblasts demonstrating that N-cadherin expression was successfully deleted in these mice. A, ameloblast layer; O, odontoblast layer.