Hao Jianjun, Ramachandran Amsaveni, George Anne
Brodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, Department of Oral Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
J Histochem Cytochem. 2009 Mar;57(3):227-37. doi: 10.1369/jhc.2008.952119. Epub 2008 Nov 11.
Formation of bone and dentin are classical examples of matrix-mediated mineralization. The mineral phase is essentially the same in these two tissues and primarily consists of a carbonated hydroxyapatite, but the difference lies in the crystal size and shape. There are three components that are necessary for proper mineralization, namely the proper synthesis and secretion of the non-collagenous proteins (NCPs), self-assembly of the collagenous matrix, and delivery of calcium and phosphate ions to the extracellular matrix. Three major NCPs present in the dentin matrix are dentin matrix protein 1 (DMP1), dentin phosphophorin (DPP), and dentin sialoprotein (DSP). In this study, we show the temporal and spatial localization of these NCPs and correlate their expression with the presence of collagenous matrix and calcified deposits in developing mouse incisors and molars. DMP1, an acidic protein, is present predominantly at the mineralization front and in the nucleus of undifferentiated preodontoblast cells. DPP, the major NCP, is present in large amounts at the mineralization front and might function to regulate the size of the growing hydroxyapatite crystals. For the first time, we report the localization of DPP in the nucleus of preodontoblast cells, suggesting a signaling function during the odontoblast differentiation process. DSP is localized predominantly in the dentinal tubules at the site of peritubular dentin, which is highly mineralized in nature. Thus, the precise localization of DMP1, DPP, and DSP in the dentin tissue suggests that a concerted effort between several NCPs is necessary for dentin formation.
骨和牙本质的形成是基质介导矿化的经典例子。这两种组织中的矿化相基本相同，主要由碳酸羟基磷灰石组成，但区别在于晶体的大小和形状。正常矿化需要三个要素，即非胶原蛋白（NCPs）的正确合成与分泌、胶原基质的自组装以及钙和磷酸根离子向细胞外基质的输送。牙本质基质中存在的三种主要NCPs是牙本质基质蛋白1（DMP1）、牙本质磷蛋白（DPP）和牙本质涎蛋白（DSP）。在本研究中，我们展示了这些NCPs的时空定位，并将它们的表达与发育中小鼠切牙和磨牙中胶原基质及钙化沉积的存在情况相关联。DMP1是一种酸性蛋白，主要存在于矿化前沿和未分化的前成牙本质细胞的细胞核中。主要的NCP DPP大量存在于矿化前沿，可能起到调节生长中的羟基磷灰石晶体大小的作用。我们首次报道了DPP在前成牙本质细胞的细胞核中的定位，这表明其在成牙本质细胞分化过程中具有信号传导功能。DSP主要定位于管周牙本质高度矿化部位的牙本质小管中。因此，DMP1、DPP和DSP在牙本质组织中的精确定位表明，几种NCPs之间协同作用对于牙本质形成是必要的。
