Gene Regulation of Rat Dentin Sialoprotein

描述(申请人提供)：在牙齿发育期间，成牙本质细胞通过产生牙本质前基质来调节牙本质的形成，随后额外的NCP被分泌到该基质中，以启动健康牙齿形成所必需的矿化过程。由于遗传性疾病，如牙本质发育不全II(DGI-II；影响每7,000名新生儿中就有1名)导致牙本质矿化异常，这些儿童除了在牙齿上放置牙冠或全口义齿外几乎没有其他选择。位于牙本质唾液蛋白(DSP)编码序列中的无义突变可能是阻止这些个体中DSP和PP表达的原因，因为这两个NCP位于单个DSP-PP转录本上。重要的是，一些DGI患者也会出现耳鸣和平衡问题，因此有必要将DSP-PP转录本和蛋白表达的问题作为一个重要的公共卫生问题来考虑。这一应用提出了一系列研究，以更好地确定DSP-PP转录本的表达和DSP/PP蛋白在牙本质矿化中的功能。该建议的具体目的是1)测试成牙本质细胞特异性因子作用于DSP-PP基因启动子的假设，调控DSP-PP基因的表达；2)测试多个DSP-PP转录本产生功能不同的PP亚型的假设，这些都是牙本质有序矿化所必需的；3)研究DSP-PP和仅DSP的转录本表达模式与牙本质矿化的关系；4)通过检测在细胞培养中DSP和PP异构体的表达对矿物质形成的影响来验证目标2和3。这些正在进行的研究结合了基因调控和蛋白质功能的方法，将揭示牙本质矿化的潜在机制，并将在以后适用于修复牙科。

DESCRIPTION (provided by applicant): During tooth development, odontoblasts modulate dentin formation by producing a predentin matrix into which additional NCPs are subsequently secreted to initiate the mineralization process so necessary for healthy tooth formation. Abnormalities in dentin mineralization due to genetic diseases such as dentinogenesis imperfecta II (DGI-II; affecting 1 in 7,000 newborns) leave these children few choices other than placement of crowns on the teeth or a complete denture. A nonsense mutation, located in the coding sequence for dentin sialoprotein (DSP) is likely responsible for blocking both DSP and phosphophoryn (PP) expression in these individuals because these two NCPs are located on a single DSP-PP transcript. Importantly, some DGI patients also experience tinnitus as well as balancing problems making it necessary to consider problems in DSP-PP transcript and protein expression as an important public health concern. This application proposes a series of studies to better define DSP-PP transcript expression and DSP/PP protein function in dentin mineralization. The specific aims of this proposal are 1) to test the hypothesis that odontoblast-specific factors acting on the DSP-PP gene promoter, regulate DSP-PP expression, 2) to test the hypothesis that multiple DSP-PP transcripts generate functionally distinct PP isoforms with distinct calcium binding capacity and hydroxyapatite forming ability which are required for orderly dentin mineralization, 3) to correlate DSP-PP transcript and DSP-only transcript expression patterns with dentin mineralization, and 4) to validate Aims 2 and 3 by examining mineral formation as a function of DSP and PP isoform expression in cell culture. These ongoing studies, which combine gene regulation and protein function approaches, will reveal underlying mechanisms of dentin mineralization and will later be applicable to reparative dentistry.