Regulation of Twist, Snail, and Id1 is conserved between the developing murine palate and tooth.

The development of both the tooth and palate requires coordinated bone morphogenetic protein (BMP) and fibroblast growth factor (FGF) signalling between epithelial and mesenchymal tissues. Here, we demonstrate that transcription factors Twist and Snail are downstream targets of FGF signalling, that Id1 and Msx2 are downstream targets of BMP signalling, and that Msx1 is regulated by both signalling pathways during tooth and palate development. We show that Twist and Snail expression in the mesenchyme is regulated by the overlying epithelium and that exogenous FGF4 in tooth and FGF2 in palate can mimic this regulation in isolated mesenchymal explants. Ids act in a dominant-negative manner to inhibit the function of other transcription factors such as Twist and Snail. FGF and BMP signalling can regulate development antagonistically, and we suggest that FGF-regulated Twist and Snail and BMP-regulated Id1 may mediate these antagonistic effects during both tooth and palate development. Copyright 2005 Wiley-Liss, Inc.