Molecular insights into the lineage-specific determination of odontoblasts: the role of Cbfa1

Department of Orthodontics, Dental Branch, Room 370, University of Texas Health Science Center at Houston, 6516 John Freeman Avenue, Houston, TX 77030, USA.

The role of stable transcription complexes in initiating and consolidating programs of gene expression during lineage specification has been extensively studied. Despite the progress made in the identification of key molecules of tooth initiation and patterning, the mechanisms leading to cell differentiation during odontogenesis are unknown. Odontoblasts are exclusive dentin-producing cells that are phenotypically and functionally distinct from osteoblasts. However, not much is known about the precise determinants of odontoblast terminal differentiation--in particular, how the fate of these cells becomes delineated from that of osteogenic mesenchyme. Cbfa1(-/-) mice completely lack osteoblasts and bone, while tooth development arrests at the time of odontoblast differentiation. The purpose of this paper is to overview our studies on the role of Cbfa1 in odontoblast determination and differentiation using the Cbfa1(-/-) mouse model and various experimental approaches. Our expression analyses confirm the down-regulation of Cbfa1 expression in newly differentiated and functional odontoblasts. Second, we demonstrate that Cbfa1(-/-) incisor organs arrest at a later stage than molars, and that alpha 1 (I) collagen, a marker of odontoblast differentiation shared in common with osteoblasts, is not significantly affected by the absence of the transcription factor. Interestingly, Dspp expression in Cbfa1(-/-) appeared markedly down-regulated in putative odontoblasts. The overexpression of Cbfa1 in an odontoblast cell line (MDPC-23) results in the selective down-regulation of Dspp and not type I collagen. It is likely that, in addition to its influence on tooth epithelial morphogenesis, Cbfa1 plays a non-redundant and stage-specific role in the lineage determination and terminal differentiation of odontoblasts from dental papilla mesenchyme.

This article has been cited by other articles:

				C. Zhang, J. Chang, W. Sonoyama, S. Shi, and C.-Y. Wang Inhibition of Human Dental Pulp Stem Cell Differentiation by Notch Signaling J. Dent. Res., March 1, 2008; 87(3): 250 - 255. [Abstract] [Full Text] [PDF]

				S. Chen, S. Rani, Y. Wu, A. Unterbrink, T. T. Gu, J. Gluhak-Heinrich, H.-H. Chuang, and M. MacDougall Differential Regulation of Dentin Sialophosphoprotein Expression by Runx2 during Odontoblast Cytodifferentiation J. Biol. Chem., August 19, 2005; 280(33): 29717 - 29727. [Abstract] [Full Text] [PDF]