Individual Predoctoral Dental Scientist Fellowship

描述（由申请人提供）：目前，对牙齿发育后期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 （TGF21）是初级牙本质细胞外基质（DECM）形成的潜在调节剂。TGF21已被证明可以从未成熟的牙乳头间充质细胞中启动成牙细胞分化。TGF21最初由牙釉质器官上皮分泌，在牙本质发生过程中，TGF21在产生牙本质的成牙细胞中表达上调，并被纳入DECM。然而，在成熟的成牙细胞中，TGF21已被证明下调DECM蛋白，如牙本质基质蛋白-1 （DMP-1）和牙本质唾液磷酸蛋白（DSPP），这两种小整合素结合配体n-连接糖蛋白（SIBLING）家族的骨/牙本质基质蛋白。基质细胞外磷酸糖蛋白（MEPE）是牙齿中最不具特征的同胞成员，在矿化中的作用似乎存在争议。初步研究表明，TGF21在Camurati-Engelmann病（CED）转基因小鼠的牙本质层和牙髓细胞中调控SIBLING蛋白和基因表达异常。CED虽然罕见，但最常见的原因是TGFB1基因的点突变导致成熟的、活性的TGF21分子过度表达。CED患者表现为严重的骨增厚和随后的软组织压迫。人类CED通过常染色体显性遗传传播，以前没有报道与牙齿异常有关。我们的假设是转基因CED小鼠模型显示牙本质形成异常，这是由成熟TGF21过表达引起的兄弟姐妹表达改变介导的，特别是MEPE。本研究旨在明确TGF21过表达对牙本质基质形成和成熟的信号作用，阐明MEPE在牙本质矿化中的作用，并确定TGF21调控MEPE表达的途径。新的小鼠模型和体外系统将被使用，并通过放射照相和矿物质密度微计算机断层扫描检查以及生化和功能分析来表征。从这些研究中获得的信息将为理解正常和病理牙本质发育的分子机制提供基础。最终，提出的研究将有助于开发新的诊断工具和治疗龋齿，各种牙齿/骨矿化疾病或牙本质形成改变综合征患者的治疗方法。本研究将阐明牙齿/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.