Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju 561-756, South Korea.
J Dent Res. 2013 Mar;92(3):215-21. doi: 10.1177/0022034512470137. Epub 2013 Jan 23.
The tooth root is an important part of the tooth that works together with the surrounding periodontium to maintain the tooth in the alveolar socket. The root develops after crown morphogenesis. While the molecular and cellular mechanisms of early tooth development and crown morphogenesis have been extensively studied, little is known about the molecular mechanisms controlling tooth root formation. Here, we show that β-catenin is strongly expressed in odontoblast-lineage cells and is required for root formation. Tissue-specific inactivation of β-catenin in developing odontoblasts produced molars lacking roots and aberrantly thin incisors. At the beginning of root formation in the mutant molars, the cervical loop epithelium extended apically to form Hertwig's epithelial root sheath (HERS), but root odontoblast differentiation was disrupted and followed by the loss of some HERS inner layer cells. However, the outer layer of the HERS extended without the root, and the mutant molars finally erupted. The periodontal tissues extensively invaded the dental pulp. These results indicate that there is a cell-autonomous requirement for Wnt/β-catenin signaling in the dental mesenchyme for root formation.
牙根是牙齿的重要组成部分，与周围的牙周组织共同作用，将牙齿固定在牙槽窝中。牙根在牙冠形态发生后发育。虽然早期牙齿发育和牙冠形态发生的分子和细胞机制已经得到广泛研究，但对于控制牙根形成的分子机制知之甚少。在这里，我们表明β-连环蛋白在成牙本质细胞系中强烈表达，并且是根形成所必需的。在发育中的成牙本质细胞中特异性地失活β-连环蛋白会导致磨牙缺乏根且切牙异常变薄。在突变磨牙的根形成开始时，颈环上皮向上延伸形成 Hertwig 上皮根鞘（HERS），但根成牙本质细胞分化受到干扰，随后一些 HERS 内层细胞丢失。然而，HERS 的外层没有根延伸，突变磨牙最终萌出。牙周组织广泛侵入牙髓。这些结果表明，Wnt/β-连环蛋白信号在牙齿间质中对于根形成具有细胞自主的要求。
