Bone Morphogenetic Protein Controls Links Between Dentinogenesis and Angiogenesis

描述(申请人提供)：口腔和周围的头面部结构的健康对一个人的整体健康和福祉是必不可少的。牙齿发育受多种信号分子和生长因子的调控，其中骨形态发生蛋白2(BMP2)起关键作用。因此，BMP2的作用不仅对了解牙齿的正常发育和异常至关重要，而且在新的牙齿结构的生物工程中也有应用。拟议的研究将确定BMP2在血管生成和牙本质形成之间的密切联系中的作用，血管相关的SMA+细胞/周细胞是连接这些过程的共同因素。牙本质涎磷蛋白(DSPP)基因在成牙本质细胞的终末分化过程中表达，并受BMP2调控，因此BMP2可能在牙本质发育不全(DGI)和牛牙症等表现为牙本质和发育缺陷的发育异常中发挥作用。我们利用两个新的BMP2条件敲除模型(BMP2-cKOSp7Cre和BMP2-CKO？SMA-CreERt2)在小鼠成牙本质细胞和部分牙髓细胞中去除了BMP2基因，评估了BMP2在牙齿发育中的作用。这些小鼠表现出严重的牙本质缺陷，血管和相关的周细胞以及干细胞减少。磨牙的牙根较短，牙髓腔扩大，与牛牙症的表型相似，成牙本质细胞中核因子I-C(NFIC)的mRNA表达减少。这种NFIC的减少是很重要的，因为NFIC基因的突变会导致人类牙根发育的主要缺陷。综上所述，这些结果表明BMP2在牙齿发育中起着关键作用，与牙本质形成和血管生成有关。这些研究的综合结果将提供关于BMP2在正常发育中的作用以及当该基因改变时发现的缺陷的基础知识。这一知识也可以应用于生物工程和牙髓再生策略，用于再生新的牙齿结构。我们的工作假设是成牙本质细胞来源于一群血管相关的周细胞，BMP2是新血管/周细胞的招募和诱导周细胞分化为成牙本质细胞所必需的。这将通过以下具体目标来解决：1)在活体内证明周细胞向成牙本质细胞分化。1b)确定BMP2在体内对周细胞的影响。2)研究BMP2在牙齿血管生成不同信号分子中的作用。这些研究将提供分子生物学、小鼠模型、组织形态计量学、免疫组织化学、免疫荧光和共聚焦分析方面的培训。所提出的研究具有创新性，因为BMP2对牙髓和牙根发育中血管生成的调节尚未被探索。这项拟议的研究具有重要意义，因为它将扩大我们对牙齿形成所涉及的复杂生物学的理解。这些发现将对后续开发治疗牙齿发育异常的新治疗方法和再生新牙齿结构的生物工程策略产生显著影响。通过这些学习，我将获得最先进的知识和技能，朝着我成为一名知名牙科科学家的目标迈进。

DESCRIPTION (provided by applicant): The health of the mouth and the surrounding craniofacial structures is essential to a person's overall health and well-being. Tooth development is regulated by many signaling molecules and growth factors, including the critical role played by bone morphogenetic protein 2 (Bmp2). Therefore, the role played by Bmp2 in not only critical to the understanding of normal tooth development and abnormalities, but also has applications in the bioengineering of new dental structures. The proposed studies will define the role of Bmp2 in the intimate association of angiogenesis and dentinogenesis, with vascular-associated ¿SMA+ cells/pericytes being the common factor linking these processes. Dentin sialophosphoprotein (DSPP) gene is expressed during terminal differentiation of odontoblasts and is regulated by Bmp2, and so a role for Bmp2 is likely in developmental abnormalities such as dentinogenesis Imperfecta (DGI) and taurodontism that show dentin and developmental defects. We have evaluated the role of Bmp2 in tooth development with the use of two novel Bmp2 conditional knockout models (Bmp2-cKOSp7Cre and Bmp2-cKO¿SMA-CreERt2) that removed the Bmp2 gene in mouse odontoblasts and a subset of dental pulp cells. These mice displayed severe dentin defects with a reduction of blood vessels and associated pericytes, as well as stem cells. The molars have short roots with an enlarged pulp chamber similar to the phenotype seen in taurodontism, and show reductions in nuclear factor I- C (Nfic) mRNA expression in odontoblasts. This Nfic reduction is important since mutations in Nfic gene results in major defects in human tooth root development. Together, these results suggest a critical role for Bmp2 in tooth development related to both dentinogenesis and angiogenesis. The combined results of these investigations will provide foundational knowledge regarding the role of Bmp2 in normal development and the defects identified when this gene is altered. This knowledge may also be applied to bioengineering and pulp regeneration strategies used to regenerate new dental structures. Our working hypothesis is that odontoblasts are derived from a population of vascular-associated pericytes, and Bmp2 is required for both the recruitment of new vessels/pericytes and the induction of pericyte differentiation into odontoblasts.. This will be addressed by the following specific aims: 1a) demonstrate the differentiation of pericytes into odontoblasts in vivo. 1b) define the effect of Bmp2 on pericytes in vivo. 2) establish the effect o Bmp2 on different signaling molecules involved in angiogenesis of the tooth. These studies will provide training in molecular biology, mouse models, histomorphometry, immunohistochemistry, immunofluorescence and confocal analysis. The proposed studies are innovative because the regulation of angiogenesis in the pulp and tooth-root development by Bmp2 has not been explored. The proposed research is significant in that it will expand our understanding of the complex biology involved in tooth formation. These findings will have a notable impact on the subsequent development of novel therapeutic approaches for the treatment of tooth developmental anomalies and on bioengineering strategies to regenerate new dental structures. Through these studies, I will acquire state-of-the-art knowledge and skills toward my goal in becoming an established dental scientist.