Enamel is the highly mineralized outer layer of teeth; the cells responsible for enamel formation are ameloblasts. Local hypoxia and hypoxia inducible factor (HIF) in embryonic tissues are important to promote normal organogenesis. However, hypoxic state in tooth germs and the roles of HIF in ameloblast differentiation have not been understood. The aim of this study is to clarify the role of HIF in ameloblast differentiation during tooth germ development. We found that tooth germs were under hypoxia and HIF-1α and HIF-2α were expressed in tooth germs in embryonic mice. Then, we used HIF inhibitors to evaluate the function of HIF during tooth germ development. The HIF-2α inhibitor significantly decreased the size of tooth germs in organ culture, while the HIF-1α inhibitor did not apparently affect the size of tooth germs. The HIF-2α inhibitor enhanced the expression of amelogenin, a marker of ameloblast differentiation, in the tooth germs in organ culture and rat dental epithelial SF2 cells. Moreover, we found that the HIF-2α inhibitor-stimulating amelogenin expression was regulated by hes-related family basic helix-loop-helix transcription factor with YRPW motif 2(Hey2) in SF2 cells. These findings suggest that the HIF-2α–Hey2 axis plays an important role in ameloblast differentiation during tooth germ development.

牙釉质是高度矿化的牙齿外层；负责牙釉质形成的细胞是成釉细胞。胚胎组织中的局部缺氧和缺氧诱导因子 (HIF) 对促进正常器官发生很重要。然而，牙胚缺氧状态和 HIF 在成釉细胞分化中的作用尚不清楚。本研究的目的是阐明 HIF 在牙胚发育过程中在成釉细胞分化中的作用。我们发现牙胚处于缺氧状态，HIF-1α 和 HIF-2α 在胚胎小鼠的牙胚中表达。然后，我们使用 HIF 抑制剂来评估 HIF 在牙胚发育过程中的功能。HIF-2α 抑制剂显着降低了器官培养物中牙胚的大小，而 HIF-1α 抑制剂对牙胚的大小没有明显影响。HIF-2α 抑制剂增强了牙釉质蛋白（成釉细胞分化的标志物）在器官培养的牙胚和大鼠牙科上皮 SF2 细胞中的表达。此外，我们发现 HIF-2α 抑制剂刺激牙釉蛋白的表达受 SF2 细胞中具有 YRPW 基序 2(Hey2) 的 hes 相关家族碱性螺旋-环-螺旋转录因子的调节。这些发现表明，HIF-2α–Hey2 轴在牙胚发育过程中的成釉细胞分化中起着重要作用。