DE-NOVO HAIR FOLLICLE MORPHOGENESIS AND HAIR TUMORS IN MICE EXPRESSING A TRUNCATED BETA-CATENIN IN SKIN

An effector of intercellular adhesion, beta-catenin also functions in Wnt signaling, associating with Lef-1/Tcf DNA-binding proteins to form a transcription factor. We report that this pathway operates in kerat inocytes and that mice expressing a stabilized beta-catenin controlled by an epidermal promoter undergo a process resembling de novo hair mo rphogenesis. The new follicles formed sebaceous glands and dermal papi lla, normally established only in embryogenesis. As in embryologically initiated hair germs, transgenic follicles induce Lef-1, but follicle s are disoriented and defective in sonic hedgehog polarization. Additi onally, proliferation continues unchecked, resulting in two types of t umors also found in humans. Our findings suggest that transient beta-c atenin stabilization may be a key player in the long-sought epidermal signal reading to hair development and implicate aberrant beta-catenin activation in hair tumors.