TRANSGENIC MODELS WITH SKELETAL REPAIR PHENOTYPES

正确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。调节发生在上皮/间充质相互作用中，涉及信号蛋白。许多蛋白质是参与牙齿发育的生长因子，并在骨形成中发挥关键作用。一种在牙齿和骨骼中重要的生长因子是转化生长因子β（TGF-β）。已经建立了含有由骨钙蛋白启动子驱动的转基因的转基因动物模型，该启动子指导成牙本质细胞、成牙骨质细胞和成骨细胞中的特异性表达，以研究TGF-β在骨中的作用。这些小鼠模型将用于研究TGF-β在牙本质和牙骨质中的作用。转基因（和所得小鼠模型）如下：1）骨中II型TGF-β的显性阴性形式。这些小鼠模型将用于研究TGF-β在牙本质和牙骨质中的作用。转基因（和所得小鼠模型）如下：1）II型TGF-β受体的显性阴性形式（IIRDN小鼠），2）组成型活性TGF-β 2配体（TGF-β 2小鼠），或3）交叉牙本质、牙骨质和骨，表明表型变化将发生在这些转基因小鼠的牙齿（如骨中所示）中。我们的初步研究支持了这一假设，并表明IIRDN小鼠的牙本质比野生型小鼠的牙本质更硬。该提案的具体目的如下：（1）通过研究IIRDN、TGF-β 2和IIRDNxTGF-β 2转基因小鼠模型的牙齿来确定TGF-β在矿化组织形成中的作用;（2）通过检查IIRDN、TGF-β 2和IIRDNxTGF-β 2转基因小鼠模型中的修复性牙本质形成来阐明TGF-β在矿化组织修复中的作用;（3）建立其他转基因小鼠模型中矿化组织缺陷的筛选方法。组织形态学、显微成像和硬度测量将用于了解TGF-β控制矿化牙基质形成的机制。进一步的研究与三种类型的小鼠作为一个近似的表型系列将使我们能够更好地了解TGF-β和个体细胞类型在体内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，通过UCSF科学界筛选其他具有骨修复缺陷的转基因小鼠的牙齿。

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.