Figure 6.

ΔNΔCβcat transgenic mice display gain-of-function β-catenin signaling phenotype in interfollicular epidermis. Tail skin sections from day 28 ΔNΔCβcatenin transgenic line and control littermates (WT) were fixed in 4% PFA fixative, embedded in OCT compound and sectioned (10 μm), and stained with hematoxylin and eosin. Shown are representative sections of A and B, tail skin follicles of WT and transgenic littermates, respectively. Hematoxylin and eosin staining revealed a phenotype in the interfollicular epidermis, reminiscent of that obtained in the ΔNβ-catenin transgenic mice. (C) X-gal staining in transgenic mice harboring both ΔNΔCβcatenin and TOPGAL. TOPGAL is activated in the de novo hair-like invaginations. (D) Multiple epithelial invaginations sprouting from the upper ORS of older follicles and the interfollicular epidermis of transgenic skin. (E) Confocal immunofluorescence image of WT 28-d tail skin, with Lef1 in green and β-catenin in red. The epidermis displays very low levels, if any, of Lef1 staining (compare staining intensity with the nuclear Lef1 in precortex). (F and G) 28-d ΔNΔCβcatenin transgenic tail skin stained for Lef1 in red and K5 in green. Arrowheads denote activation of Lef1 in hair placodes and hair germs. (F and G) Arrows denote ectopic expression of LEF1 in the basal layer of epidermis of 28-d transgenic animals.