beta-catenin signaling can initiate feather bud development

Intercellular signaling by a subset of Wnts is mediated by stabilization of cytoplasmic beta-catenin and its translocation to the nucleus: Immunolocal ization of beta-catenin in developing chick skin reveals that this signalin g pathway is active in a dynamic pattern from the earliest stages of feathe r bud development. Forced activation of this pathway by expression of a sta bilized beta-catenin in the ectoderm results in the ectopic formation of fe ather buds. This construct is sufficient to induce bud formation since it d oes so both within presumptive feather tracts and in normally featherless r egions where tract-specific signals are absent. It is also insensitive to t he lateral inhibition that mediates the normal spacing of buds and can indu ce ectopic buds in interfollicular skin. However, additional patterning sig nals cooperate with this pathway to regulate gene expression within domains of stabilized beta-catenin expression. Localized activation of this pathwa y within the bud as it develops is required for normal morphogenesis and ec topic activation of the pathway leads to abnormally oriented buds and growt hs on the feather filaments. These results suggest that activation of the b eta-catenin pathway initiates follicle development in embryonic skin and pl ays important roles in the subsequent morphogenesis of the bud.