EFFECTS OF DENTIN MATRIX PROTEINS ON MINERALIZATION

长期目标是了解细胞外基质蛋白，磷蛋白（PP）在生物矿化特别是牙本质中所起的作用。牙本质磷蛋白（DPP）对钙离子和胶原蛋白有很强的亲和力，是牙本质中矿物质的成核剂和晶体生长的控制剂。通过更好地了解DPP的作用，将有可能设计预防和/或治疗，以改善牙齿发育不全，牙齿畸形和修复缺陷，以应对龋齿和洞制备。在大鼠和小鼠中，DPP似乎是由暂时命名的牙本质唾液磷蛋白基因编码的单个转录物的切割产物（里奇和王，1996，麦克杜格尔等人，1997年）。最近，申请人与里奇博士和卢瑟福博士合作克隆了人DSPP基因（Gu等人，1998年和未发表的数据），现在可以使用体外表达系统和位点特异性诱变来产生活性和突变重组蛋白，这些蛋白可用于评估DPP在人牙本质矿化中的功能作用。因此，以下具体目的将通过以下方式检验DPP是牙本质中晶体羟基磷灰石生长的主要核和控制器的假设：（i）在体外系统中使用重组和天然来源的DPP诱导和控制羟基磷灰石晶体生长。(ii)评估成牙本质细胞在人组织培养系统中显著表达转导的野生型或突变型DPP的能力。

DESCRIPTION The long term objective is to understand the role played by the extracellular matrix protein, phosphoprotein (PP) in biomineralization especially of dentin. Dentin phosphoprotein (DPP) has a great affinity for both calcium and collagen and appears to be the nucleator of mineral and controller of crystal growth in dentin. By better understanding the role of DPP it will be possible to devise preventive and/or therapies that will ameliorate tooth aplasia, tooth malformations and faulty repair in response to caries and cavity preparation. In rat and mouse DPP appears to be a cleavage product of a single transcript that is encoded for by the provisionally named dentin sialophosphoprotein gene (Ritchie and Wang, 1996, MacDougall et al., 1997). Recently the applicant in collaborations with Drs. Ritchie and Rutherford have cloned the human DSPP gene (Gu, et al. 1998 and unpublished data) and it is now possible to use in vitro expression systems and site specific mutagenesis to produce active and mutant recombinant proteins that can be used to assess the functional role of DPP in human dentin mineralization. Thus the following specific aims will test the hypothesis that DPP is the major nuclear and controller of crystal hydroxyapatite growth in dentin by: (i) Inducing and controlling hydroxyapatite crystal growth using recombinant and naturally sourced DPP's in an in vitro system. (ii) Assessing the ability of odontoblasts to significantly express transduced wild type or mutant DPP in a human tissue culture system.