Identification of novel genes expressed during mouse tooth development by microarray gene expression analysis

Abstract

To identify genes heretofore undiscovered as critical players in the biogenesis of teeth, we have used microarray gene expression analysis of the developing mouse molar tooth (DMT) between postnatal day (P) 1 and P10 to identify genes differentially expressed when compared with 16 control tissues. Of the top 100 genes exhibiting increased expression in the DMT, 29 were found to have been previously associated with tooth development. Differential expression of the remaining 71 genes not previously associated with tooth development was confirmed by quantitative reverse transcription-polymerase chain reaction analysis. Further analysis of seven of the latter genes by mRNA in situ hybridization found that five were specific to the developing tooth in the craniofacial region (Rspo4, Papln, Amtn, Gja1, Maf). Of the remaining two, one was found to be more widely expressed (Sp7) and the other was found to be specific to the nasal serous gland, which is close to, but distinct from, the developing tooth (Vrm).

Fig. 1

Volcano plot showing differential expression between the dental molar teeth (DMT) and control tissues. A positive Log₂ ratio between DMT and control tissues indicates increased expression of the gene in the DMT, a negative value indicates reduced expression.

Fig. 2

A–E: In situ hybridization of Gja1 (A), and Maf (B), Papln (C), Amtn (D), Rspo4 (E) in incisor tooth germs. “a” and “c” are hematoxylin and eosin–stained sections, and “b” and “d” are stained for mRNA in situ analysis. “a” and “b” are at ×10 magnification, and “c” and “d” are at ×40 magnification. The asterisk indicates the position of the ameloblasts (A–D) or odontoblasts (E). Arrows indicate the localization of gene expression.

Fig. 3

A–E: In situ hybridization of Gja1 (A), and Maf (B), Papln (C), Amtn (D), Rspo4 (E) in molar tooth germs. “a” and “c” are hematoxylin and eosin–stained sections, and “b” and “d” are stained for mRNA in situ analysis. “a” and “b” are at ×10 magnification, and “c” and “d” are at ×40 magnification. The asterisk indicates the position of the ameloblasts (A–D) or odontoblasts (E). Arrows indicate the localization of gene expression.