Characterization of DMP1 a dentin phosphoprotein

描述（由申请人提供）：牙本质形成是一个涉及细胞级联和细胞外事件的动态过程。细胞-细胞、细胞-基质和基质-基质等特定的相互作用事件负责成牙本质分化和矿化牙本质基质的组装。矿化过程中的问题在许多牙齿病理中都很明显。牙本质再生和修复的成功依赖于将成牙本质细胞前体招募到原位的能力，随后是这些细胞的成熟过程、基质沉积和有机基质的最终矿化。非胶原酸性蛋白被认为在矿物成核过程中起调节作用，调节羟基磷灰石晶体大小及其形态。牙本质基质蛋白1 （DMP1）是我们首次从成牙细胞cDNA文库中克隆到的细胞外基质蛋白。DMP1是典型的阴离子，具有多个钙结合位点，被认为通过成核羟基磷灰石促进矿化。我们报道的一个有趣的发现是DMP1可以执行多种功能。非磷酸化的DMP1在成牙细胞早期分化过程中被发现转移到细胞核，并在调节生物矿化特异性基因的表达中起作用。这些研究的中心假设是DMP1在成牙细胞成熟过程中起着重要而独特的作用，导致矿化牙本质的形成。因此，我们提出了3个具体目标来探索DMP1介导的成牙细胞分化和矿化基质形成的机制：(1)研究DMP1在成牙细胞分化过程中的细胞靶点；(2)阐明DMP1基因在成牙细胞分化过程中的调控分子机制；(3)确定DMP1能否在干细胞中诱导成牙细胞谱系。了解矿化过程对生物医学和牙科领域很重要，因为正常生物矿化的破坏可能导致病理性钙化或脱矿过程。长期目标是了解DMP1在牙本质矿化中发挥独特作用的调节机制。

DESCRIPTION (provided by applicant): Dentinogenesis is a dynamic process that involves a cascade of cellular and extracellular events. Specific interactive events like cell-cell, cell-matrix and matrix-matrix are responsible for odontoblast differentiation and the assembly of the mineralized dentin matrix. Problems in the mineralization process are evident in a number of dental pathologies. Successful dentin regeneration and repair in dentistry relies on the ability to recruit odontoblast precursors to the site followed by maturation process of these cells, matrix deposition and ultimately mineralization of the organic matrix. Noncollagenous acidic proteins have been postulated to play a regulatory role in de novo mineral nucleation, regulating hydroxyapatite crystal size as well as its morphology. Dentin matrix protein 1 (DMP1) is an extracellular matrix protein that was first cloned by us from an odontoblast cDNA library. DMP1 is typically anionic and has multiple calcium binding sites and is thought to promote mineralization by nucleating hydroxyapatite. An intriguing finding that we have reported is that DMP1 can perform multiple functions. Non-phosphorylated DMP1 was found to translocate to the nucleus during early differentiation of odontoblasts and function in regulating the expression of biomineralization-specific genes. The central hypothesis of the proposed studies is that DMP1 plays an important and unique role during maturation of odontoblasts, leading to the formation of mineralized dentin. Therefore 3 specific aims are proposed to pursue the mechanisms responsible for DMP1 mediated odontoblast differentiation and mineralized matrix formation: (1) To study the cellular targets of DMP1 during odontoblast differentiation; (2) To elucidate the molecular mechanisms of DMP1 gene regulation during odontoblast differentiation; (3) To determine if DMP1 can induce odontoblast lineage in stem cells. Understanding the mineralization process is important to the biomedical and dentistry fields as disruption of normal biomineralization can lead to pathological calcification or demineralization process. The long-term goal is to understand the regulatory mechanism by which DMP1 plays a unique role in dentin mineralization. PUBLIC HEALTH RELEVANCE: Odontoblasts, the principal cells responsible for dentin formation synthesize proteins that are responsible for dentin mineralization. One such protein that we have identified is Dentin matrix protein 1. In this proposal we intend to identify the mechanism by which this molecule functions in the odontoblast differentiation process. Once we have characterized the function of DMP1 in dentin formation, then we could use this molecule for regenerating dentin and thus replace synthetic materials that are currently being used in endodontic practices.