Park Joo-Cheol, Park Jong-Tae, Son Ho-Hyun, Kim Heung-Joong, Jeong Moon-Jin, Lee Chang-Seop, Dey Rama, Cho Moon-Il
Department of Oral Histology, College of Dentistry, Chosun University, Gwang-Ju, Korea.
Eur J Oral Sci. 2007 Apr;115(2):153-60. doi: 10.1111/j.1600-0722.2007.00435.x.
This study investigated the expression and localization of APin (which was previously identified and cloned from a rat odontoblast cDNA library), during ameloblast differentiation in rat incisors, by using in situ hybridization and immunohistochemistry. The subcellular localization of APin varied during ameloblast differentiation, but was stage-specific. APin mRNA was not expressed in pre-ameloblasts, was weakly expressed in secretory ameloblasts, and was strongly expressed in maturation-stage ameloblasts as well as in the junctional epithelium attached to the enamel of erupted molars. In the maturation-stage ameloblasts, APin protein was conspicuous in the supranuclear area (Golgi complex) of smooth-ended ameloblasts as well as in both the supranuclear area and the ruffle end of ruffle-ended ameloblasts. During ameloblast-lineage cell culture, APin was expressed at a low level in the early stages of culture, but at a high level in the late stage of culture, which was equivalent to the maturation stage. APin protein was efficiently secreted from transfected cells in culture. Furthermore, its overexpression and inactivation caused an increase and decrease in matrix metalloproteinase-20 (MMP-20) and tuftelin expression, respectively. These findings indicate a functional role for APin in the mineralization and maturation of enamel that is mediated by the expression of MMP-20 and tuftelin.
本研究采用原位杂交和免疫组织化学方法，调查了APin（先前从大鼠成牙本质细胞cDNA文库中鉴定并克隆）在大鼠切牙成釉细胞分化过程中的表达和定位情况。在成釉细胞分化过程中，APin的亚细胞定位有所变化，但具有阶段特异性。APin mRNA在前成釉细胞中不表达，在分泌期成釉细胞中弱表达，而在成熟期成釉细胞以及与萌出磨牙釉质相连的结合上皮中强表达。在成熟期成釉细胞中，APin蛋白在平滑端成釉细胞的核上区（高尔基体复合体）以及皱褶端成釉细胞的核上区和皱褶端均很明显。在成釉细胞系细胞培养过程中，APin在培养早期低水平表达，但在培养后期高水平表达，后者相当于成熟阶段。APin蛋白在培养的转染细胞中能有效分泌。此外，其过表达和失活分别导致基质金属蛋白酶-20（MMP-20）和牙本质磷蛋白表达增加和减少。这些发现表明APin在釉质矿化和成熟过程中发挥功能性作用，该作用由MMP-20和牙本质磷蛋白的表达介导。
