Tooth Root Formation: An Emerging Signaling Pathway

牙根形成：新兴信号通路

• 批准号: 8729715
• 负责人: JIAN Q. FENG
• 金额: $ 29.1万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-18 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8729715
• 关键词: Acceleration; Amelogenesis Imperfecta; Area; Belief; Biological; Bone Morphogenetic Proteins; Cartilage; Cell Differentiation process; Cell Proliferation; Cells; Clinical; Complex; Data; Defect; Dental; Dental Enamel; Dental Pulp; Dental crowns; Dentin; Dentin Formation; Dentinogenesis; Dentistry; Development; Educational process of instructing; Epithelial; Epithelium; Event; Exhibits; Extracellular Matrix; Figs - dietary; Future; Genetic Engineering; Goals; Hereditary Disease; Incisor; Inhibition of Cell Proliferation; Injection of therapeutic agent; Injury; Knock-out; Knockout Mice; Knowledge; Link; Mediating; Medical Students; Mesenchymal; Modeling; Molecular; Morphogenesis; Mus; Natural regeneration; Odontoblasts; Osteoblasts; Osteogenesis; Patients; Phenotype; Plant Roots; Play; Positioning Attribute; Publishing; Pulp Canals; Regulation; Repair Complex; Research Proposals; Role; Series; Signal Pathway; Signal Transduction; Signaling Molecule; Stem Cell Research; Structure; Tamoxifen; Testing; Tooth Crowns; Tooth Fractures; Tooth Germ; Tooth root structure; Tooth structure; Translations; Trauma; Up-Regulation; Work; bone; bone morphogenetic protein receptors; human NFIC protein; insight; keratin 5; mineralization; mouse model; novel; postnatal; public health relevance; research study; transcription factor

DESCRIPTION (provided by applicant): Despite the advances made in identifying the signaling pathways in tooth germ and crown morphogenesis, the precise molecular events leading to root formation are largely unknown. Since dentin forms the bulk of the root, such knowledge is critical for exploring how pulpal cells respond to injury by forming a reparative dentin matrix and for developing predictable therapies for dentin-pulp complex repair. The current belief is that root development is initiated from HERS (Hertwig's Epithelial Root Sheath), but amelogenesis imperfecta patients exhibit no apparent root defects. Our recent data showed that the target deletion of Bmpr1a in epithelium by keratin 5 Cre induced at E14.5 leads to severe enamel defects but showed no apparent root dentin phenotype, suggesting that molecules originating from mesenchymal cells may play critical roles during root formation. The root dentinogenesis model offers a practical means of studying how odontoblast differentiation is regulated at the molecular level. In this study, we will perform a series of experiments to test the hypothesis that BMPR1A signaling originating from pulp/odontoblast cells controls root formation via a novel NFIC-OSX-¿-catenin-DSPP signaling pathway. We have proposed three Aims. In specific Aim 1 we will test the hypothesis that OSX is a key downstream molecule of BMPR1A. To test this hypothesis, we will use the 3.2 Col 1ERTM-Cre (induced by injection of Tamoxifen) to determine the degree to which re-expression of Osx1 can rescue the abnormal root phenotype in Bmpr1a cKO. In Specific Aim 2 we will test the hypothesis that OSX controls root dentinogenesis through (i) the inhibition of cell proliferation and (ii) the acceleration of cll differentiation via the inhibition of ?-catenin and upregulation of DSPP. In Specific Aim 3 we will test the hypothesis that NFIC, an essential transcriptional factor for root dentinogenesis, is a ke downstream molecule of BMP, which controls root dentinogenesis via OSX. To test this hypothesis, we will re-express Nfic in the Bmpr1a cKO osteoblasts to determine the degree to which Nfic can rescue the abnormal root phenotype. We will also re-express Osx in the Nfic KO odontoblasts to determine the degree to which re-expression of Osx can rescue the abnormal root phenotype. Upon completion of this project in an understudied area, we will provide new mechanistic insights into the role of these signaling molecules from mesenchymal cells during root formation. This valuable information will not only challenge the current dogma (induction of root signal is from HERS) but will also be applied to the development of new bioactive restorative therapies aimed at restoring the integrity of the dentin-pulp complex after injury.

描述（由申请人提供）：尽管在识别牙胚和牙冠形态发生中的信号通路方面取得了进展，但导致牙根形成的精确分子事件在很大程度上是未知的。由于牙本质形成了牙根的大部分，因此这些知识对于探索牙髓细胞如何通过形成修复性牙本质基质对损伤做出反应以及开发牙本质牙髓复合体修复的可预测疗法至关重要。目前的观点认为，牙根的发育是从HERS（Hertwig上皮根鞘）开始的，但牙釉质发育不全的患者没有表现出明显的牙根缺陷。我们最近的数据表明，角蛋白5 Cre在E14.5诱导的上皮中Bmpr 1a的靶向缺失导致严重的釉质缺陷，但没有表现出明显的根牙本质表型，这表明源自间充质细胞的分子可能在根形成过程中起关键作用。牙根牙本质发生模型为研究成牙本质细胞分化在分子水平上的调控提供了一种实用的方法。在这项研究中，我们将进行一系列的实验，以测试 起源于牙髓/成牙本质细胞的BMPR 1A信号通过一种新的NFIC-OSX-<$-catenin-DSPP信号通路控制牙根形成的假说。我们提出了三个目标。在具体目标1中，我们将测试OSX是BMPR 1A的关键下游分子的假设。为了检验这一假设，我们将使用3.2 Col 1 ERTM-Cre（通过注射他莫昔芬诱导）来确定Osx 1的再表达可以挽救Bmpr 1a cKO中异常根表型的程度。在具体目标2中，我们将检验OSX通过（i）抑制细胞增殖和（ii）通过抑制？catenin和DSPP的上调。在第三阶段，我们将 验证了以下假设，即根牙本质形成的必需转录因子NFIC是BMP的下游分子，BMP通过OSX控制根牙本质形成。为了验证这一假设，我们将在Bmpr 1a cKO成骨细胞中重新表达Nfic，以确定Nfic可以挽救异常根表型的程度。我们还将在Nfic KO成牙本质细胞中重新表达Osx，以确定Osx的重新表达可以在多大程度上挽救异常的根部表型。在一个未充分研究的领域完成这个项目后，我们将提供新的机制见解，这些信号分子在根形成过程中从间充质细胞的作用。这些有价值的信息不仅将挑战目前的教条（根信号的诱导来自HERS），而且还将应用于开发新的生物活性修复疗法，旨在恢复损伤后牙本质牙髓复合体的完整性。