Lu Yongbo, Zhang Shubin, Xie Yixia, Pi Yuli, Feng Jian Q
Department of Oral Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
Cells Tissues Organs. 2005;181(3-4):241-7. doi: 10.1159/000091385.
Dentin matrix protein 1 (DMP1) is highly expressed in mineralized tooth and bone. Both in vitro and in vivo data show that DMP1 is critical for mineralization and tooth morphogenesis (growth and development). In this study, we studied Dmp1 gene regulation. The in vitro transient transfection assay identified two important DNA fragments, the 2.4- and 9.6-kb promoter regions. We next generated and analyzed transgenic mice bearing the beta-galactosidase (lacZ) reporter gene driven by the 2.4- or 9.6-kb promoter with the complete 4-kb intron 1. The 9.6-kb Dmp1-lacZ mice conferred a DMP1 expression pattern in odontoblasts identical to that in the endogenous Dmp1 gene. This is reflected by lacZ expression in Dmp1-lacZ knock-in mice during all stages of odontogenesis. In contrast, the 2.4-kb Dmp1-lacZ mice display activity in odontoblast cells only at the early stage of odontogenesis. Thus, we propose that different transcription factors regulate early or later cis-regulatory domains of the Dmp1 promoter, which gives rise to the unique spatial and temporal expression pattern of Dmp1 gene at different stages of tooth development.
牙本质基质蛋白1（DMP1）在矿化的牙齿和骨骼中高度表达。体外和体内数据均表明，DMP1对矿化和牙齿形态发生（生长和发育）至关重要。在本研究中，我们研究了Dmp1基因调控。体外瞬时转染试验鉴定出两个重要的DNA片段，即2.4 kb和9.6 kb的启动子区域。接下来，我们构建并分析了携带由2.4 kb或9.6 kb启动子驱动的β-半乳糖苷酶（lacZ）报告基因且带有完整4 kb内含子1的转基因小鼠。9.6 kb Dmp1-lacZ小鼠在成牙本质细胞中赋予了与内源性Dmp1基因相同的DMP1表达模式。这在Dmp1-lacZ基因敲入小鼠牙齿发育的所有阶段的lacZ表达中得到体现。相比之下，2.4 kb Dmp1-lacZ小鼠仅在牙齿发育早期在成牙本质细胞中显示活性。因此，我们提出不同的转录因子调节Dmp1启动子的早期或晚期顺式调控结构域，这导致Dmp1基因在牙齿发育的不同阶段呈现独特的时空表达模式。
