Runx2 and dental development

Abstract

The Runx2 gene is a master transcription factor of bone and plays a role in all stages of bone formation. It is essential for the initial commitment of mesenchymal cells to the osteoblastic lineage and also controls the proliferation, differentiation, and maintenance of these cells. Control is complex, with involvement of a multitude of factors, thereby regulating the expression and activity of this gene both temporally and spatially. The use of multiple promoters and alternative splicing of exons further extends its diversity of actions. RUNX2 is also essential for the later stages of tooth formation, is intimately involved in the development of calcified tooth tissue, and exerts an influence on proliferation of the dental lamina. Furthermore, RUNX2 regulates the alveolar remodelling process essential for tooth eruption and may play a role in the maintenance of the periodontal ligament. In this article, the structure of Runx2 is described. The control and function of the gene and its product are discussed, with special reference to developing tooth tissues, in an attempt to elucidate the role of this gene in the development of the teeth and supporting structures.

In vitro evaluation of the odontogenic potential of mouse undifferentiated pulp cells

“…This can be explained by the fact that RUNX2 is essential for tooth development up to the bell stage, being necessary for the formation of the enamel knot, which controls growth and folding of the enamel organ epithelium (24). Other authors corroborate our findings showing that RUNX2 (type II) is strongly expressed in dental papilla mesenchyme, with up-regulation in pre-odontoblasts and no expression in differentiated odontoblasts (25). The results obtained in this investigation suggest that OD-21 undifferentiated pulp cells have potentiality to differentiate into odontoblast-like cells via chemical stimuli, emphasizing the importance of these cells in the process of odontogenesis as well as tissue regeneration.…”

Inhibition of the terminal differentiation of odontoblasts and their transdifferentiation into osteoblasts in Runx2 transgenic mice

“…Runx2 protein was transiently detected in ameloblasts in the coronal regions of wildtype mice at one week of age as previously reported (Fig. 1c, d) (D'Souza et al, 1999;Jiang et al, 1999;Camilleri and McDonald 2006). The expression pattern of the transgene in the mandible was examined bygalactosidase activity using lacZ transgenic mice under the control of the 2.3 kb Col1a1 promoter (Tg(Col1a1-lacZ) mice) at 3 days of age (Fig.…”

Hertwig's epithelial root sheath cells do not transform into cementoblasts in rat molar cementogenesis

“…To date, Runx2 has been detected in both epithelial and mesenchymal cells in various kinds of mineralized and non-mineralized tissues (Bronckers et al, 2001). In mineralized tissues, it has been established that Runx2 regulates the differentiation of mineralization-inducing cells, viz., osteoblasts (bone), ameloblasts (enamel), odontoblasts (dentin), and cementoblasts (cementum) (D'Souza et al, 1999;Ducy et al, 1999;Ducy, 2000;Bronckers et al, 2001;Zhao et al, 2002;Camilleri and McDonald, 2006). From these, we considered that Runx2 could be used as a marker for mineralization-inducing cells in cementogenesis.…”