Department of Maxillofacial Orthognathics, Division of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
Department of Maxillofacial Orthognathics, Division of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
Gene Expr Patterns. 2021 Jun;40:119182. doi: 10.1016/j.gep.2021.119182. Epub 2021 May 10.
The Hippo pathway is essential for determining organ size by regulating cell proliferation. Previous reports have shown that impairing this pathway causes abnormal tooth development. However, the precise expression profile of the members of the transcriptional enhanced associate domain family (Tead), which are key transcription factors mediating Yap function, during tooth development is unclear. In this study, among the four isoforms of Tead (Tead1 - 4), only the expression of Tead1 mRNA was observed using semiquantitative RT- PCR in murine developing tooth germ at E16.5. The expression level of Tead1 mRNA in the excised murine mandibular molar tooth germ was significantly higher at E16.5 than at other developmental stages, as determined using quantitative PCR. We found that the mRNA expression of connective tissue growth factor (Ctgf), which is one of the Yap target genes directly controlling cell growth, changed consistently with that of Tead1 in developing molars. Fluorescent immunostaining revealed that Tead1 protein was expressed in both epithelial cells and mesenchymal cells of the dental lamina and dental epithelium, including the primary enamel knot during the cap stage. During the early bell stage (E16.5), Tead1 was expressed intensely in the inner and outer enamel epithelium, including the secondary enamel knot and the neighboring mesenchymal cells. Tead1 then specifically localized to the inner and outer enamel epithelium, which is responsible for enamel formation during the bell stage. These expression patterns were consistent with those of Yap, Taz, and Ctgf protein in developing molars. These results suggest that Tead1 acts as a mediator of the biological functions of Yap, such as the morphogenesis of cusp formation, during tooth development.
Hippo 通路对于通过调节细胞增殖来确定器官大小至关重要。先前的报道表明，破坏该途径会导致牙齿发育异常。然而，在牙齿发育过程中，转录增强相关域家族（Tead）成员的精确表达谱，这些成员是介导 Yap 功能的关键转录因子，尚不清楚。在本研究中，在 Tead 的四个同工型（Tead1-4）中，仅在用半定量 RT-PCR 检测 E16.5 时观察到 Tead1 mRNA 在小鼠发育牙胚中的表达。用定量 PCR 测定，在 E16.5 时，从切除的小鼠下颌磨牙胚中 Tead1 mRNA 的表达水平明显高于其他发育阶段。我们发现，连接组织生长因子（Ctgf）的 mRNA 表达，其是直接控制细胞生长的 yap 靶基因之一，与发育中的磨牙中的 Tead1 mRNA 表达一致。荧光免疫染色显示，Tead1 蛋白在牙板和牙上皮的上皮细胞和间充质细胞中表达，包括帽状期的初级釉结。在早期钟状期（E16.5），Tead1 在包括次级釉结和邻近间充质细胞在内的内釉上皮和外釉上皮中强烈表达。然后，Tead1 特异性定位到负责钟状期釉质形成的内釉上皮和外釉上皮。这些表达模式与 Yap、Taz 和 Ctgf 蛋白在发育中的磨牙中的表达模式一致。这些结果表明，Tead1 作为 Yap 的生物学功能的介导物发挥作用，例如牙尖形成的形态发生，在牙齿发育过程中。
