DSPP signaling in dentinogenesis

描述（由申请人提供）：这些研究的长期目标是阐明牙本质唾液磷蛋白（DSPP）在牙本质形成中的机制，从而为诱导牙齿修复和再生提供新的途径。牙本质中最丰富和最重要的蛋白质是I型胶原和DSPP。DSPP突变与牙本质发育不全（DGI）有关，DGI是最常见的牙本质遗传疾病。DSPP蛋白被蛋白酶加工成几个功能片段；DSP， DPP等。这些结构域在牙本质形成过程中发挥着独特的生物学功能。初步数据显示1)。BMP2诱导DSPP表达。BMP2缺失小鼠的牙齿与DSPP突变的DGI相似，BMP2敲除小鼠的DSPP、Dlx3和Osx转录因子的表达也降低；2）. MMP-9特别催化DSP生成nh2端和cooh端片段。DSP的NH2-端和cooh端片段在齿状分布上有明显的差异。MMP-9缺失小鼠出现牙齿缺损和DSPP加工干扰。3）. nh2末端和cooh末端结构域在细胞膜上与其受体整合素26和CD105结合。基于这些发现，我们提出了以下假设：DSPP的转录调控、翻译后修饰和信号转导对牙本质生物矿化的发生、速率和程度具有重要的控制作用。为了验证这一假设，我们提出以下具体目标：确定牙本质形成过程中DSPP转录中的BMP2信号通路。2. 利用MMP-9测定DSP的加工模式和切割位点。3. 在牙齿发育过程中通过整合素26和CD105确定DSP信号通路。这是一个创新的假设，认为DSP/DSPP的转录、翻译后加工和信号转导的每一步都是健康牙本质形成所必需的。这些知识将促进我们对威胁牙本质结构完整性的遗传性疾病的发病机制的理解，并为治疗牙本质疾病提供潜在的线索。

DESCRIPTION (provided by applicant): The long-ranged goal of these studies is to elucidate the mechanism (s) of dentin sialophosphoportein (DSPP) in dentinogenesis and thereby provide new avenues for inducing the repair and regeneration of teeth. The most abundant and important proteins in dentin are collagen type I and DSPP. Mutations of DSPP are associated with dentinogenesis imperfectas (DGI), the most common dentin genetic disorders. DSPP protein is processed by proteases into several functional fragments; DSP, DPP and others. These domains play unique biological functions during dentinogenesis. Preliminary data showed that 1). BMP2 induced DSPP expression. Teeth in BMP2 null mice are similar to DGI with DSPP mutations and expression of DSPP and Dlx3 and Osx transcriptional factors were also decreased in BMP2 knock-out mice; 2). MMP-9 specially catalyzes DSP into the NH2-terminal and COOH-terminal fragments. The NH2- and COOH-terminal fragments of DSP show a clear difference in tooth distributions. Defect in teeth and interference of DSPP processing were seen in MMP-9 null mice. 3). The NH2-terminal and COOH-terminal domains bind to their receptors, integrin 26 and CD105, on cellular membrane. Based on these findings, we propose the following hypothesis that the transcriptional regulation, posttranslational modification and signal transduction of DSPP are important for controlling the initiation, rate and extent of dentin biomineralization. To test this hypothesis, we propose the following Specific Aims: 1. to determine BMP2 signaling pathways in DSPP transcription during dentinogenesis. 2. To determine processing patterns of DSP and cleaved sites of DSP by MMP-9. 3. To determine DSP signaling pathways via integrin 26 and CD105 during tooth development. This is an innovative hypothesis that each step of transcription, posttranslational processing and signaling transduction of DSP/DSPP is necessary for the formation of healthy dentin. Such knowledge will advance our understanding of the pathogenesis of inherited disorders that threaten the structural integrity of dentin and provide a potential clue for treating dental diseases. PUBLIC HEALTH RELEVANCE: Dentin sialophosphoprotein (DSPP) protein is important for dentin formation as DSPP mutations cause dentinogenesis imperfectas, the most common dentin genetic diseases. Here, we propose a novel pathway for DSPP transcriptional regulation, proteolytic processing and signaling transduction pathway for dentinogenesis. Thereafter, better understanding of the mechanisms of DSPP biological functions will provide new avenues for repair and regeneration of teeth.