J Bone Miner Res. 2014 Jun;29(6):1446-55. doi: 10.1002/jbmr.2153.
Microarray analysis of odontoblastic cells treated with sodium fluoride has identified the asporin gene as a fluoride target. Asporin is a member of the small leucine-rich repeat proteoglycan/protein (SLRP) family that is believed to be important in the mineralization process. In this study, asporin expression and distribution were investigated by systematic analysis of dentin and enamel, with and without fluoride treatment. Specific attention was focused on a major difference between the two mineralized tissues: the presence of a collagenous scaffold in dentin, and its absence in enamel. Normal and fluorotic, continually growing incisors from Wistar rats treated with 2.5 to 7.5 mM sodium fluoride (NaF) were studied by immunochemistry, in situ hybridization, Western blotting, and RT-qPCR. Asporin was continuously expressed in odontoblasts throughout dentin formation as expected. Asporin was also found, for the first time, in dental epithelial cells, particularly in maturation-stage ameloblasts. NaF decreased asporin expression in odontoblasts and enhanced it in ameloblasts, both in vivo and in vitro. The inverse response in the two cell types suggests that the effector, fluoride, is a trigger that elicits a cell-type-specific reaction. Confocal and ultrastructural immunohistochemistry evidenced an association between asporin and type 1 collagen in the pericellular nonmineralized compartments of both bone and dentin. In addition, transmission electron microscopy revealed asporin in the microenvironment of all cells observed. Thus, asporin is produced by collagen-matrix-forming and non-collagen-matrix-forming cells but may have different effects on the mineralization process. A model is proposed that predicts impaired mineral formation associated with the deficiency and excess of asporin.
应用于氟化物处理牙胚细胞的微阵列分析，鉴定出富脯氨酸蛋白聚糖/蛋白（SLRP）家族中的 asporin 基因为氟化物的靶基因。Asporin 被认为在矿化过程中发挥着重要作用，是一种小富含亮氨酸重复的糖蛋白/蛋白。在这项研究中，通过对有/无氟化物处理的牙本质和釉质进行系统分析，研究了 asporin 的表达和分布。特别关注了这两种矿化组织之间的一个主要区别：牙本质中存在胶原支架，而釉质中不存在。通过免疫化学、原位杂交、Western blot 和 RT-qPCR 研究了用 2.5 至 7.5mmol/L 氟化钠（NaF）处理的 Wistar 大鼠的正常和氟斑牙不断生长的切牙。结果显示，正如预期的那样，Asporin 在牙本质形成过程中持续在成牙本质细胞中表达。Asporin 还首次在牙胚上皮细胞中被发现，特别是在成熟阶段的成釉细胞中。体内和体外实验均表明，NaF 降低了成牙本质细胞中 asporin 的表达，增强了成釉细胞中 asporin 的表达。两种细胞类型的反应呈相反趋势，表明效应物氟化物是一种引发细胞类型特异性反应的触发因素。共聚焦和超微结构免疫组织化学证实了 asporin 与骨和牙本质中细胞周非矿化区的 I 型胶原之间的关联。此外，透射电子显微镜显示 asporin 存在于观察到的所有细胞的微环境中。因此，Asporin 由形成胶原基质的细胞和不形成胶原基质的细胞产生，但可能对矿化过程有不同的影响。提出了一个模型，预测与 asporin 缺乏和过量相关的矿化形成受损。
