TRANSGENIC MODELS WITH SKELETAL REPAIR PHENOTYPES

适当的牙齿形状和细胞组成的形成涉及一个高度有序和受调控的过程。调节发生在涉及信号蛋白的上皮/间充质相互作用中。许多蛋白质是生长因子，参与牙齿发育并在骨形成中发挥关键作用。其中一种对牙齿和骨骼都很重要的生长因子是转化生长因子β(转化生长因子-β)。已经建立了转基因动物模型，该转基因动物模型包含由骨钙素启动子驱动的转基因基因，该基因在成牙本质细胞、成牙骨质细胞和成骨细胞中特异性表达，以研究转化生长因子β在骨中的作用。这些小鼠模型将被用来研究转化生长因子-β在牙本质和牙骨质中的作用。转基因(以及由此产生的小鼠模型)如下：1)骨中II型转化生长因子-β的显性阴性形式。这些小鼠模型将被用来研究转化生长因子-β在牙本质和牙骨质中的作用。转基因(以及由此产生的小鼠模型)如下：1)II型转化生长因子-β受体(IIRDN小鼠)的显性阴性形式，2)固有活性的转化生长因子-β2配体(转化生长因子-β2小鼠)，或3)牙本质、牙骨质和骨的交叉，表明这些转基因小鼠的牙齿(如骨骼)将发生表型变化。我们的初步研究支持了这一假说，并表明IIRDN小鼠的牙本质比野生型小鼠的牙本质更硬。该建议的具体目的如下：(1)通过研究IIRDN、转化生长因子-β2和转化生长因子-β2转基因小鼠模型的牙齿，确定转化生长因子-β在矿化组织形成中的作用；(2)通过检测转基因小鼠模型中修复性牙本质的形成，阐明转化生长因子-β在矿化组织修复中的作用；(3)建立筛选其他现有转基因小鼠模型中矿化组织缺陷的方法。将利用组织形态计量学、显微成像和硬度测量来了解转化生长因子-β控制矿化牙齿基质形成的机制。进一步将这三种类型的小鼠作为一个近似的表型系列进行研究，将使我们能够更好地了解转化生长因子-β和单个细胞类型在活体牙齿结构和功能中的作用。此外，这些研究将使我们能够开发工具，从加州大学旧金山分校科学界提供的其他具有骨修复缺陷的转基因小鼠中筛选牙齿。

Formation of the proper tooth shape and cellular composition involves a highly ordered and regulated process. Regulation occurs within epithelial/mesenchymal interactions involving signaling proteins. Many of the proteins are growth factors which are involved in tooth development and play key roles in bone formation. One such growth factor important in teeth as well as bones, is transforming growth factor beta (TGF-beta). Transgenic animal models that contain a transgene driven by the osteocalcin promoter, which directs specific expression in odontoblasts, cementoblasts, and osteoblasts have been =created to study the effects of TGF-beta in bone. These mice models will be used to study the role of TGF-beta in dentin and cementum. The transgenes (and resultant mouse models) are as follows: 1) a dominant negative form of the type II TGF- beta in bone. These mice models will be used to study the role of TGF- beta in dentin and cementum. The transgenes(and resultant mouse models) are as follows: 1) a dominant negative form of the type II TGF-beta receptor (IIRDN mice), 2) a constitutively active TGF-beta2 ligand (TGF- beta2 mice), or 3) a cross dentin, cementum, and bone, suggests that phenotypic changes would occur in the teeth (as shown in bone) of these transgenic mice. Our preliminary studies have supported this hypothesis, and have shown that the dentin of the IIRDN mice is harder than dentin from the wild type mice. The specific aims of the proposal are as follows: (1) to determine the role of TGF-beta in the formation of mineralized tissues by studying the teeth of the IIRDN, TGF-beta2, and IIRDNxTGF-beta2 transgenic mouse models; (2) to elucidate the role of TGF-beta in repair of mineralized tissues by examining reparative dentin formation in IIRDN, TGF-beta2, and IIRDNxTGF-beta2 transgenic mouse models; (3) to develop a screening protocol for defects in mineralized tissues in other available transgenic mice models. Histomorphometry, microimaging, and hardness measurements will be utilized to understand the mechanism by which TGF- beta controls the formation of mineralizing tooth matrices. Further studies with the three types of mice as an approximately phenotypic series will allow us to better understand the role of TGF- beta and individual cell types in tooth structure and function in vivo. In addition, these studies will allow us to develop tools for screening teeth from other transgenic mice with bone repair defects available through the UCSF scientific community.