Expression survey of genes critical for tooth development in the human embryonic tooth germ

Abstract

In the developing murine tooth, the expression patterns of numerous regulatory genes have been examined and their roles have begun to be revealed. To unveil the molecular mechanisms that regulate human tooth morphogenesis, we examined the expression patterns of several regulatory genes, including BMP4, FGF8, MSX1, PAX9, PITX2, and SHOX2, and compared them with that found in mice. All of these genes are known to play critical roles in murine tooth development. Our results show that these genes exhibit basically similar expression patterns in the human tooth germ compared with that in the mouse. However, slightly different expression patterns were also observed for some of the genes at certain stages. For example, MSX1 expression was detected in the inner enamel epithelium in addition to the dental mesenchyme at the bell stage of the human tooth. Moreover, FGF8 expression remained in the dental epithelium at the cap stage, while PAX9 and SHOX2 expression was detected in both dental epithelium and mesenchyme of the human tooth germ. Our results indicate that, although slight differences exist in the gene expression patterns, the human and mouse teeth not only share considerable homology in odontogenesis but also use similar underlying molecular networks. Developmental Dynamics 236:1307-1312, 2007.

Msx1 Mutations

“…Also, a study with human embryonic tissue revealed a few differences in gene expression patterns-for example, PAX9 is not exclusively expressed in tooth bud mesenchyme but is also found in the dental epithelium (Lin et al, 2007). Ultimately, we will have to find valid in vitro assays that may help to interpret mouse data on a human background.…”

Epithelial – Mesenchymal Interactions in Tooth Development and the Significant Role of Growth Factors and Genes with Emphasis on Mesenchyme – A Review

“…The pathway includes genes encoding the actual signals, their receptors and mediators of signaling pathways and transcription factors. These genes primarily were associated with major interactions and process involved in development and maturation of teeth namely Msx gene, Pax gene, Shh gene, Wnt/ beta -Catenin signaling, Cbfa-1 gene [36][37][38][39] [Table/ Fig-6]. …”

“…The significance of the gene was recognized in the fact that Msx1 creates modulation to cap stage through various stages of ectomesenchyme proliferation and condensation [37]. Mice defects for Msx 1 and 2 results in failure of epithelial mesenchymal interactions and defects like anodontia or hypodontia and cleft palate occur.…”

Mutations in the Human Homeobox MSX1 Gene in the Congenital Lack of Permanent Teeth

“…, are among them, but MSX1 seems to be of a special significance as it appears to play the most important role during early tooth development (Lin et al 2007). In fact, there are the PAX9, AXIN2 and MSX1 genes, which are evidenced to be implicated in non-syndromic agenesis (Vieira et al 2004;Letra et al 2008) The MSX1 gene is located on the chromosome 4 and belongs to the homeobox Msx gene family related to the Drosophila msh-like gene family.…”