Verstraeten Barbara, Sanders Ellen, van Hengel Jolanda, Huysseune Ann
Evolutionary Developmental Biology, Ghent University, Ghent, Belgium.
BMC Dev Biol. 2010 Jun 1;10:58. doi: 10.1186/1471-213X-10-58.
The development of teeth is the result of interactions between competent mesenchyme and epithelium, both of which undergo extensive morphogenesis. The importance of cell adhesion molecules in morphogenesis has long been acknowledged but remarkably few studies have focused on the distribution and function of these molecules in tooth development.
We analyzed the expression pattern of an important epithelial cadherin, E-cadherin, during the formation of first-generation teeth as well as replacement teeth in the zebrafish, using in situ hybridization and whole mount immunostaining to reveal mRNA expression and protein distribution. E-cadherin was detected in every layer of the enamel organ during the different stages of tooth development, but there were slight differences between first-generation and replacement teeth in the strength and distribution of the signal. The dental papilla, which is derived from the mesenchyme, did not show any expression. Remarkably, the crypts surrounding the functional teeth showed an uneven distribution of E-cadherin throughout the pharyngeal region.
The slight differences between E-cadherin expression in zebrafish teeth and developing mouse and human teeth are discussed in the light of fundamental differences in structural and developmental features of the dentition between zebrafish and mammals. Importantly, the uninterrupted expression of E-cadherin indicates that down-regulation of E-cadherin is not required for formation of an epithelial tooth bud. Further research is needed to understand the role of other cell adhesion systems during the development of teeth and the formation of replacement teeth.
牙齿的发育是有能力的间充质与上皮之间相互作用的结果，二者均经历广泛的形态发生过程。细胞黏附分子在形态发生中的重要性早已得到认可，但令人惊讶的是，很少有研究关注这些分子在牙齿发育中的分布和功能。
我们利用原位杂交和整体免疫染色来揭示mRNA表达和蛋白质分布，分析了一种重要的上皮钙黏蛋白E-钙黏蛋白在斑马鱼第一代牙齿以及替换牙形成过程中的表达模式。在牙齿发育的不同阶段，釉质器官的每一层均检测到E-钙黏蛋白，但第一代牙齿和替换牙在信号强度和分布上存在细微差异。源自间充质的牙乳头未显示任何表达。值得注意的是，围绕功能性牙齿的隐窝在整个咽区显示出E-钙黏蛋白的分布不均。
鉴于斑马鱼和哺乳动物牙列在结构和发育特征上的根本差异，讨论了斑马鱼牙齿与发育中的小鼠和人类牙齿中E-钙黏蛋白表达的细微差异。重要的是，E-钙黏蛋白的持续表达表明上皮牙胚的形成不需要E-钙黏蛋白的下调。需要进一步研究以了解其他细胞黏附系统在牙齿发育和替换牙形成过程中的作用。
