Characterization of DMP1 a Dentin Phosphoprotein

描述(申请人提供)：该项目的长期目标是了解控制生物矿化的分子机制。我们最初发现牙本质基质蛋白1(DMP1)是成牙本质细胞中的一种非胶原性蛋白，后来又在成骨细胞中发现。我们和其他人的大量研究表明，DMP1可能在生物矿化过程中发挥关键作用。最近我们发现DMP1可以刺激成骨前细胞和成牙本质前细胞内钙离子的释放。为了补充内质网，质膜上的钙通道需要被激活，以允许钙从细胞外空间进入。DMP1刺激导致钙离子通道(即钙离子通道)耗尽和随后开放的分子机制尚不清楚。因此，了解DMP1如何介导细胞内钙释放和内流是一个新的概念。存储操作钙内流(SOCE)是细胞调节基础钙离子、补充细胞内钙离子和执行广泛的专门化活动的主要细胞过程。我们还鉴定了两个DMP1相互作用蛋白，即GRP-78(葡萄糖调节蛋白-78)和TRIP-1(转化生长因子-β受体II相互作用蛋白1)。GRP-78和TRIP-1都是内质网驻留蛋白。因此，DMP1刺激的中心是内质网。这一建议的统一假设是，DMP1刺激细胞内钙离子的释放调节了广泛的细胞功能，包括成骨细胞和成牙本质细胞的存活和分化。这一结果将产生与理解控制骨和牙本质矿化的分子机制相关的新信息。目前，还没有通道分子被用于矿化相关疾病的治疗或诊断。因此，这项研究的结果将有助于确定骨和牙本质修复和再生的潜在治疗靶点。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the molecular mechanisms that control biomineralization. We originally identified Dentin matrix protein 1 (DMP1) a noncollagenous protein in odontoblasts and later in osteoblasts. Numerous studies by us and others suggest that DMP1 might play critical roles in the biomineralization process. Recently we discovered that DMP1 can stimulate the release of intracellular calcium in preosteoblasts and preodontoblasts. To refill the ER, plasma membrane Ca 2+ channels need to be activated to permit Ca 2+ entry from the extracellular space. The molecular mechanism by which DMP1 stimulation leads to store depletion and subsequent opening of Ca2+ permeable ion channels namely store-operated calcium channels are not known. Therefore, understanding how DMP1 mediates intracellular calcium release and influx is a new concept. Store operated calcium entry (SOCE) is a principal cellular process by which cells regulate basal Ca2+, refill intracellular Ca2+ and execute a wide range of specialized activities. We also identified two DMP1 interacting proteins, namely, GRP-78 (Glucose-regulated protein- 78) and TRIP-1 (TGF-beta receptor II interacting protein 1). Both GRP-78 and TRIP-1 are ER resident proteins. Thus, the epicenter for DMP1 stimulation is the endoplasmic reticulum. The unifying hypothesis of this proposal is that the release of intracellular Ca2+ by DMP1 stimulation regulates a wide range of cellular functions including osteoblast and odontoblast survival and differentiation. The result wil generate new information that is relevant to understanding molecular mechanisms that control mineralization in bone and dentin. Currently, no channel molecule has been exploited for either therapy or diagnosis of mineralization related disorders. Therefore, the outcomes from this study will help define potential therapeutic targets for bone and dentin repair and regeneration.