Reuptake of Extracellular Amelogenin by Dental Epithelial Cells Results in Increased Levels of Amelogenin mRNA through Enhanced mRNA Stabilization*
Reuptake of Extracellular Amelogenin by Dental Epithelial Cells Results in Increased Levels of Amelogenin mRNA through Enhanced mRNA Stabilization*
复制标题
DOI：
10.1074/jbc.m507695200
复制
发表时间：
2006-01
影响因子：
4.8
通讯作者：
Liming Xu;H. Harada;T. Yokohama‐Tamaki;Shuichiro Matsumoto;J. Tanaka;A. Taniguchi
中科院分区：
文献类型：
--
作者：
Liming Xu;H. Harada;T. Yokohama‐Tamaki;Shuichiro Matsumoto;J. Tanaka;A. Taniguchi
成釉原蛋白是由成釉细胞分泌的细胞外基质蛋白，是釉质基质的主要成分。近年来，釉质蛋白除了在牙釉质形成中的作用外，在细胞分化过程中的生物活性也得到了广泛的认识。本研究考察了成釉原蛋白对成釉细胞分化的生物学活性。重组小鼠淀粉原蛋白（rm-amelogenin）在培养的牙上皮细胞系（HAT-7）中增强了内源性淀粉原蛋白mRNA的表达，尽管淀粉原蛋白启动子活性缺乏增加。为了解决这一差异，我们分析了rm-amelogenin对amelogenin mRNA稳定性的影响。amelogenin mRNA的半衰期极短，但在rm-amelogenin的存在下，其半衰期比对照延长了3倍。此外，我们还发现外源性异硫氰酸荧光素偶联的rm-淀粉原蛋白进入HAT-7细胞的细胞质。从我们的结果可以看出，外源性淀粉原蛋白通过稳定HAT-7细胞细胞质中的mRNA来增加淀粉原蛋白mRNA水平。我们推测，在分化过程中，牙上皮细胞利用一种独特的机制来增加淀粉原蛋白的产生，即对分泌的淀粉原蛋白的再摄取。
Amelogenin is an extracellular matrix protein secreted by ameloblasts and is a major component of enamel matrix. Recently, in addition to their role in enamel formation, the biological activity of enamel proteins in the process of cell differentiation has recently become widely appreciated. In this study, we examined the biological activity of amelogenin on ameloblast differentiation. Recombinant mouse amelogenin (rm-amelogenin) enhanced the expression of endogenous amelogenin mRNA in a cultured dental epithelial cell line (HAT-7), despite a lack of increased amelogenin promoter activity. To solve this discrepancy, we analyzed the effects of rm-amelogenin on the stability of amelogenin mRNA. The half-life of amelogenin mRNA is extremely short, but in the presence of rm-amelogenin its half-life was extended three times longer than the control. Furthermore, we showed the entry of exogenous fluorescein isothiocyanate-conjugated rm-amelogenin into the cytoplasm of HAT-7 cells. It follows from our results that exogenous amelogenin increases amelogenin mRNA levels through stabilization of mRNA in the cytoplasm of HAT-7 cells. Here we speculated that during differentiation, dental epithelial cells utilize a unique mechanism for increasing the production of amelogenin, the reuptake of secreted amelogenin.