Microarray analysis of pre- and postnatal murine dental papilla

Objectives: Epithelial-mesenchymal interaction is significantly important during tooth development, and a lot of genes are associated with odontogenesis. It has been reported that disappearance of important factors on odontogenesis is evident at 0-3 postnatal days in recombination of murine enamel organ and papilla. Based on this result, we hypothesized that genes on odontogenesis were down-regulated in dental papilla after birth, and microarray analysis was employed in pre- and postnatal dental papilla to identify those down-regulated genes. Methods: Embryos of ICR mice at 16-day (E-16) and 18-day (E-18, equal 0 postnatal day), and postnatal 3- and 10-day old (P-3, P-10) mice were used. Dental papillae and pulps were dissected from the first mandibular molar germs to extract total RNA with enzyme treatment. Biotin-labeled cRNA was synthesized from and hybridized with GeneChip mouse genome 2.0 array, and subsequently data were normalized and analyzed by GeneSpring software. Microarray data were confirmed by quantitative RT-PCR (QRT-PCR). Results: We selected the genes which had over 2.0-fold differences. The number of up-regulated gene was decreased following the tooth morphogenesis. On the other hand, there was the most number of down-regulated genes (2924) at E-18 and P-3. Down-regulate of Adamts4, Lef1, Aldha1a2 and Rag1 were recognized at both E-16 and E-18, and expression of Plxnc1, Pitx2 and Uhrf1 was reduced at P-18 and P-3. The expression of Aldh1a2, Adamts4 and Plxnc1 were examined by QRT-PCR analysis showed reduction of their expression after birth (Aldh1a2 1/17, Adamts4 1/3, Plxnc1 1/3, p<0.05). Conclusion: These results suggest that three genes; Aldh1a2, Adamts4, and Plxnc1 selected by microarray analysis have a possibility to odontogenesis-related genes in dental papilla. This study was supported by grants-in-Aid for Scientific Research, #17591926, from the Japanese Ministry of Education, Science, Sports and Culture.