Fig. 2. Mitogenic Wnt signaling is transduced through the ß-catenin/TCF pathway in neural precursors across the DV axis. (a) Dominant-active ß-catenin causes a large expansion in the ventricular zone and a reduction in post-mitotic neurons. (b-d) Dominant-active ß-catenin reduces D1, D2, D3, V1 and V2 interneurons and ventral motor neurons. (e) Triple staining for GFP, TUNEL and Isl1 shows that dominant-active ß-catenin reduces differentiation of motorneurons prior to and independent of inducing apoptosis. (f-h) Dominant-active ß-catenin causes precursor expansion at dorsal (f), intermediate (g), and ventral (h) levels without primarily changing positional information. (i,j) Dominant negative TCF4 cell-autonomously blocks precursors from entering S-phase of the cell cycle across the DV axis. Arrows mark cells on the transfected side that were not transfected (i) and are BrdU positive (j). All images are representative of at least 5 transfected embryos.
