Lef1 expression is activated by BMP-4 and regulates inductive tissue interactions in tooth and hair development.

TLDR

Targeted inactivation of the murine LEF‑1 gene abolishes formation of organs that depend on epithelial‑mesenchymal interactions. The study recombines epithelial and mesenchymal tissues from normal and LEF‑1‑deficient embryos at various developmental stages to delineate LEF‑1‑dependent steps in tooth and whisker organogenesis. The authors perform tissue recombination of epithelial and mesenchymal components from normal and LEF‑1‑deficient embryos at multiple developmental stages. The experiments reveal that mesenchymal Lef1 is required for whisker epithelial primordium initiation but not for tooth, that transient epithelial Lef1 expression is needed for mesenchymal papilla formation and organogenesis, that Lef1 activity is transmitted between tissues, and that BMP‑4 can activate Lef1, indicating a regulatory role in BMP‑mediated inductive interactions.

Abstract

Targeted inactivation of the murine gene encoding the transcription factor LEF-1 abrogates the formation of organs that depend on epithelial-mesenchymal tissue interactions. In this study we have recombined epithelial and mesenchymal tissues from normal and LEF-1-deficient embryos at different stages of development to define the LEF-1-dependent steps in tooth and whisker organogenesis. At the initiation of organ development, formation of the epithelial primordium of the whisker but not tooth is dependent on mesenchymal Lef1 gene expression. Subsequent formation of a whisker and tooth mesenchymal papilla and completion of organogenesis require transient expression of Lef1 in the epithelium. These experiments indicate that the effect of Lef1 expression is transmitted from one tissue to the other. In addition, the finding that the expression of Lef1 can be activated by bone morphogenetic protein 4 (BMP-4) suggests a regulatory role of this transcription factor in BMP-mediated inductive tissue interactions.