Are odontogenesis-related genes detected with microarray really involved in odontogenesis?

小鼠牙乳头发育过程中的重要因素在出生前和出生后的发育阶段之间消失。因此，我们假设牙齿乳头中涉及牙齿形成的某些基因在出生前/出生后受到下调。我们的目标是通过微阵列分析确定哪些基因下调。从胚胎16天、18天(E16、E18)和出生后3天(P3)的小鼠下颌第一磨牙胚胎中分离出牙乳头，并进行基因芯片分析。E16~E18间下调基因数为2269个，E18~P3间为3130个。在E16和E18观察到Adamts4、Aldha1a2和Lef1的急剧下调(折叠变化和10.0)，定量RT-PCR显示它们的表达在出生后减少(Adamts4，1/3；Aldh1a2，1/13；Lef1，1/37)。这些结果表明，这三个基因的下调是牙齿乳头正常发育的一个重要因素。为了确定这些基因是否参与牙齿发育，我们构建了这些基因的表达载体。将基因导入成人牙髓细胞，与牙体上皮结合，移植于肾被膜下。然而，在组织学上看不到牙齿发育。需要进一步的研究来确认这些基因与牙齿发育有关。

Important factors involved in odontogenesis in mouse dental papillae disappear between the pre- and post-natal stages of development. Therefore, we hypothesized that certain genes involved in odontogenesis in dental papillae were subject to pre-/post-natal down-regulation. Our goal was to identify, by microarray analysis, which genes were down-regulated. Dental papillae were isolated from embryonic 16-day-, 18-day- (E16, E18), and post-natal 3-day-old (P3) murine first mandibular molar germs and analyzed by microarray. The number of down-regulated genes was 2269 between E16 and E18, and 3130 between E18 and P3. Drastic down-regulation (fold change > 10.0) of Adamts4, Aldha1a2, and Lef1 was observed at both E16 and E18, and quantitative RT-PCR revealed a post-natal reduction in their expression (Adamts4, 1/3; Aldh1a2, 1/13; and Lef1, 1/37). These results suggest that down-regulation of these three genes is an important factor in normal odontogenesis in dental papillae. To confirm whether these genes are involved in odontogenesis or not, we constructed expression vectors of these genes. We transfected the genes into adult pulp cells and combined with dental epithelium, and transplanted under kidney capsule. However, odontogenesis could not be seen histologically. Further investigation is necessary to confirm that these genes are involved in odontogenesis.