Fig. 3.
Precocious and sustained activation of Lef1/β-catenin and P-PTEN/PI3K/AKT signaling in hair follicles lacking BMPR1A. (A–E) cKOTM and CONTM mice were targeted for Bmpr1a ablation at P44 and analyzed at P59. Frozen skin sections (10 μm) were subjected to indirect immunofluorescence or immunohistochemistry by using the antibodies indicated in the lower right of each frame. Color coding is according to the fluorescent tags of the secondary antibodies. Arrowheads denote aberrant expression. (F) Immunoblot analyses of protein extracts isolated from P59 skin preparations as described (26). Antibodies used are indicated at the right. (G and H) TOPFlash assays. MKs were transfected with vector encoding the reporter gene TOPFlash or the control FOPFlash containing mutations in the multimerized Lef1 DNA binding sites. MKs were then treated with the recombinant factors or with the PI3K inhibitor Ly as indicated, and luciferase assays were conducted as described (13). Experiments were conducted in triplicate. Lam5, laminin5; β-cat, β-catenin; β4, β4-integrin; hg, hair germs; DP, dermal papilla; Nogg, Noggin; Wnt3, Wnt3a.