Investigating the roles of Hh signaling and Gli1+ cells in primary and reparative dentinogenesis in mouse molars

项目摘要/摘要 诱导成牙本质细胞分泌的间充质干细胞群体的鉴定 牙本质在生长(原牙本质形成)和修复(修复性牙本质形成)过程中是至关重要的 改进的牙髓治疗、牙本质再生以及最终的功能生物工程的发展 牙。尽管在体内鉴定小鼠切牙内的间充质干细胞方面取得了重大进展，但我们知道 更不用说小鼠磨牙中的间充质干细胞，与门牙不同的是，它不会持续生长，而且 类似于人类的牙列。本研究的目的是审查目前存在争议的 Hhedgehog(HH)信号通路和Gli1，一种转录因子，是激活的 小鼠磨牙原发和修复性牙本质形成中典型的HH信号通路。两个具体目标 已经被提出了。目标1中的实验旨在测试这一假设，即在发育中的小鼠磨牙中， 牙间充质中的HH信号和Gli1表达细胞可分化为原代成牙本质细胞。使用世系 追踪与Gli1-CreERT2；Ai9报告小鼠我们将研究Gli1-Cre-td在番茄表达中的作用 HhAntag对原代成牙本质细胞的作用及HhAntag对HH信号的抑制作用 Shh途径的抑制剂对Gli1-Cre-td番茄细胞的激活及其在原代培养中的作用 成牙本质细胞。Aim 2中的实验旨在测试这一假设，即在成年小鼠的磨牙中，HH信号 牙髓中表达Gli1的细胞参与第二代成牙本质细胞的形成 和修复性牙本质再生。我们将在成人磨牙体内进行实验性牙髓暴露和 观察牙髓暴露后Shh配体和Gli1的表达。Gli1-Cre-td对番茄的贡献 修复性牙本质形成过程中向第二代成牙本质细胞表达细胞的实验研究 HH信号对修复性牙本质形成的抑制及Gli1-Cre-td在番茄表达中的作用 第二代成牙本质细胞的细胞将通过Gli1-1中的细胞谱系追踪实验进行检测。 CreerT2；Ai9报告鼠。建议对不连续生长的小鼠磨牙进行的研究 与人类牙列更接近，将使我们能够更好地理解HH信号和Gli1的作用 在原发和修复性牙本质形成中表达细胞，这是一个以前没有研究过的领域。

PROJECT SUMMARY / ABSTRACT Identification of the mesenchymal stem cell (MSC) population capable of giving rise to odontoblasts secreting dentin during growth (primary dentinogenesis) and repair (reparative dentinogenesis) is critical for the development of improved pulp therapy, regeneration of dentin and ultimately the bioengineering of functional teeth. Despite significant progress in the identification of MSCs within the mouse incisors in vivo, we know much less about MSCs in mouse molars that, unlike incisors, are not continuously growing and are more similar to human dentition. The goal of the present study is to examine the currently controversial roles of the Hedgehog (Hh) signaling pathway and Gli1, a transcription factor that is a downstream effector of the activated canonical Hh signaling pathway in primary and reparative dentinogenesis in mouse molars. Two specific aims have been proposed. Experiments in Aim 1 are designed to test the hypothesis that in growing mice molars, Hh signaling and Gli1 expressing cells in dental mesenchyme give rise to primary odontoblasts. Using lineage tracing and Gli1-CreERT2; Ai9 reporter mice we will examine the contribution of Gli1-Cre-tdTomato expressing cells to primary odontoblasts and the effects of inhibition of Hh signaling by HhAntag, a potent small molecule inhibitor of the Shh pathway, on the activation of Gli1-Cre-tdTomato+ cells and their contribution to primary odontoblasts. Experiments in Aim 2 are designed to test the hypothesis that in adult mice molars, Hh signaling and Gli1 expressing cells in the dental pulp are involved in the formation of second-generation odontoblasts and reparative dentinogenesis. We will perform experimental pulp exposure in adult molars in vivo and examine the expression of Shh ligand and Gli1 after pulp exposure. The contribution of Gli1-Cre-tdTomato expressing cells to second generation of odontoblasts during reparative dentinogenesis and the effects of inhibition of Hh signaling on reparative dentinogenesis and the contribution of Gli1-Cre-tdTomato expressing cells to second generation of odontoblasts will be examined by cell lineage-tracing experiments in GLi1- CreERT2; Ai9 reporter mice. The proposed studies in mouse molars that are not continuously growing and more similar to human dentition will enable us to gain a better understanding of roles of Hh signaling and Gli1 expressing cells in primary and reparative dentinogenesis, an area that has not been studies before.