Establishment and characterization of rat dental epithelial derived ameloblast-lineage clones
Establishment and characterization of rat dental epithelial derived ameloblast-lineage clones
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DOI：
10.1263/jbb.103.479
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发表时间：
2007-05-01
影响因子：
2.8
通讯作者：
Noma, Takafumi
中科院分区：
文献类型：
--
作者：
Abe, Kaori;Miyoshi, Keiko;Noma, Takafumi
牙齿是最坚硬的组织，上面覆盖着成釉细胞产生的釉质。成釉细胞的分化受牙齿形态发生过程中上皮-间充质相互作用的控制。然而，成釉细胞分化的分子机制尚不清楚。为了解决这个问题，我们开发了一种体外检测系统来评估成釉发生的分子机制。首先，我们从6日龄的大鼠切牙建立了牙上皮来源的克隆，并确定克隆SRE-GS的细胞是最大的釉原蛋白mRNA的产生细胞。接下来，我们分析了几种化学物质对SRE-GS细胞中釉原蛋白表达的影响。只有丝裂原活化蛋白激酶(MAPK)激动剂能促进釉原蛋白的表达。这一发现与免疫组织化学数据显示在成釉细胞分化过程中存在磷酸化形式的p38、c-jun氨基末端激酶(JNK)和细胞外信号调节激酶(ERK)相一致。为了研究MAPK信号的作用，我们比较了山奈霉素和水杨酸钠对牙齿相关分化标志物表达的影响。茴香霉素和水杨酸钠均可诱导釉原蛋白、ABCG2和Bmp4基因的表达，下调p75NGFR基因的表达。而碱性磷酸酶、胞外素、骨形态发生蛋白2和Fgf8基因的表达仅被苯甲霉素上调。这些结果表明，MAPK信号至少部分地作为成釉细胞分化的诱导剂发挥作用。
Teeth are the hardest tissues covered with enamel produced by ameloblasts. The ameloblast differentiation is controlled by sequential epithelial-mesenchymal interactions during tooth morphogenesis. However, the molecular mechanism of ameloblast differentiation remains unclear. To address this question, we developed an in vitro assay system to evaluate the molecular mechanism of amelogenesis. First, we established dental epithelium-derived clones from 6-day-old rat incisors and established that cells of the clone SRE-GS were the largest producers of amelogenin mRNA. Next, we analyzed the effects of several chemicals on the amelogenin expression in SRE-GS cells. Only mitogen-activated protein kinase (MAPK) activators enhanced amelogenin mRNA expression. This finding corresponded to the immunohistochemical data showing the presence of phosphorylated forms of p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) during ameloblast differentiation. To examine the roles of MAPK signals, we compared the effects of anisomycin and sodium salicylate on the expression of tooth-related differentiation markers. Both anisomycin and sodium salicylate induced amelogenin, Abcg2, and Bmp4 mRNA and down-regulated p75NGFR mRNA. On the other hand, ALP, ectodin, Bmp2 and Fgf8 mRNA were up-regulated only by anisomycin. These results indicate that MAPK signaling functions, at least in part, as the inducer of ameloblast differentiation.