Individual Predoctoral Dental Scientist Fellowship

描述（由申请人提供）：目前，对牙齿发育后期的组织特异性基因调控知之甚少，特别是与牙本质矿化相关的基因调控。最近的研究已经确定转化生长因子-β 1（TGF-21）作为一个潜在的调节剂的初级牙本质细胞外基质（DECM）的形成。TGF-21已被证明可以启动未成熟牙乳头间充质细胞向成牙本质细胞分化。TGF 21最初由釉质器官上皮分泌，已显示在初级牙本质发生期间在产生牙本质的成牙本质细胞中上调，并掺入DECM中。然而，在成熟的成牙本质细胞中，TGF 21已被证明下调DECM蛋白，如牙本质基质蛋白-1（dentin matrix protein-1，TGF-1）和牙本质唾液磷蛋白（dentin sialophosphoprotein，DSPP），它们是骨/牙本质基质蛋白的小整合素结合配体N-连接糖蛋白（SIBLING）家族中的两种。基质细胞外磷酸糖蛋白（MEPE）是牙齿中最不具特征的SIBLING成员，在矿化中的作用似乎存在争议。初步研究表明，TGF-21失调的SIBLING蛋白和基因表达的牙本质层和牙髓细胞的一种新的转基因小鼠模型的Camurati-Engelmann病（CED）。CED虽然罕见，但最常见的是由于TGFB 1基因中的点突变导致成熟的活性TGF 21分子过表达。CED患者表现为严重的骨增厚和随后的软组织压迫。通过常染色体显性遗传，CED在人类中尚未被报道与牙齿异常。我们的假设是，转基因CED小鼠模型显示异常的牙本质形成介导的SIBLING，特别是MEPE，由成熟TGF 21的过度表达引起的表达改变。具体的目的是寻求确定的信号转导的影响，TGF 21的过度表达对牙本质基质的形成和成熟，澄清MEPE在牙本质矿化的功能，并确定TGF 21调节Mepe表达的方式。将使用新型小鼠模型和体外系统，并通过放射照相和矿物质密度显微计算机断层扫描检查以及生化和功能测定沿着进行表征。从这些研究中获得的信息将为理解正常和病理性牙本质发育的分子机制提供基础。最终，拟议的研究将促进新的诊断工具和治疗龋齿，各种牙齿/骨矿化疾病，或改变牙本质形成的综合征的患者的治疗方法的发展。这项研究将阐明牙齿/骨基质材料特性在口腔和骨骼健康和疾病中的作用。

DESCRIPTION (provided by applicant): Currently, very little is known regarding tissue-specific gene regulation during the later stages of tooth development, especially those associated with dentin mineralization. Recent studies have identified transforming growth factor-beta 1 (TGF21) as a potential modulator of primary dentin extracellular matrix (DECM) formation. TGF21 has been shown to initiate odontoblast cytodifferentiation from immature dental papilla mesenchymal cells. Initially secreted by enamel organ epithelium, TGF21 has been shown to be upregulated in dentin-producing odontoblasts during primary dentinogenesis and become incorporated into the DECM. In mature odontoblasts, however, TGF21 has been shown to downregulate DECM proteins such as dentin matrix protein-1 (DMP-1) and dentin sialophosphoprotein (DSPP), two of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family of bone/dentin matrix proteins. Matrix extracellular phosphoglycoprotein (MEPE), the least characterized SIBLING member in teeth, seems to have controversial roles in mineralization. Preliminary studies demonstrate that TGF21 dysregulates SIBLING protein and gene expression in the dentin layer and in pulp cells of a novel transgenic mouse model for Camurati-Engelmann disease (CED). CED, though rare, is most often due to a point mutation in the TGFB1 gene leading to overexpression of the mature, active TGF21 molecule. Patients with CED present with severe bone thickening and subsequent soft tissue compression. Transmitted through autosomal dominant inheritance, CED in humans has not been previously reported to be associated with dental abnormalities. Our hypothesis is that the transgenic CED mouse model displays abnormal dentin formation as mediated by altered expression of the SIBLINGs, in particular MEPE, caused by the overexpression of mature TGF21. The specific aims seek to identify the signaling effects that overexpression of TGF21 has on dentin matrix formation and maturation, to clarify the function of MEPE in dentin mineralization, and to determine the way in which TGF21 regulates Mepe expression. Novel mouse models and in vitro systems will be used and characterized by way of radiographic and mineral density microcomputed tomography examinations, along with biochemical and functional assays. The information obtained from these studies will provide a foundation for understanding the molecular mechanisms involved in both normal and pathological dentin development. Eventually the proposed studies will facilitate the development of novel diagnostic tools and therapeutic treatments for patients with dental caries, various tooth/bone mineralization disorders, or syndromes with altered dentin formation. This research will elucidate the role of tooth/bone matrix material properties in oral and skeletal health and disease.