Figure 3. Tnks promotes Axin regulation during the early phase, but is dispensable for Axin proteolysis during the delayed phase after Wg exposure.

(a-f) Wild-type Axin is initially stabilized and subsequently degraded following Wg exposure. Stage 9 and mid-stage 10 embryos expressing Axin-V5 driven by the mat-Gal4 driver, co-stained with V5 and Wg antibodies. Genotypes left, antibodies top. (a–c) By 40 min after the onset of Wg exposure (stage 9), Axin-V5 is distributed in wide segmental stripes (brackets) that overlap narrow Wg stripes (asterisks). (d–f) By 120 min after the onset of Wg exposure (mid-stage 10), Axin-V5 staining is decreased in cells expressing Wg (asterisks). (g–l) The Tnks-binding domain in Axin is required for the initial stabilization of Axin induced by Wg exposure, but dispensable for the subsequent Wg-dependent Axin proteolysis. (g–i) In stage 9 embryos, AxinΔTBD-V5 staining is uniformly high throughout the embryonic ectoderm; no segmental stripes are present. (j–l) In mid-stage 10 embryos, the AxinΔTBD-V5 levels are decreased in cells expressing Wg (asterisks). Axin stripes are spatially juxtaposed with Wg stripes. (m–r) Tnks is required for the initial stabilization of Axin induced by Wg exposure, but dispensable for the subsequent Wg-dependent Axin proteolysis. (m–o) In stage 9 Tnks null mutant embryos, Axin-V5 staining is uniformly high in all ectodermal cells. (p–r) In mid-stage 10 Tnks null mutant embryos, Axin-V5 is decreased in cells expressing Wg (asterisks). Axin stripes are spatially juxtaposed with Wg stripes. Scale bar, 25 μm. Schematic illustration of spatial relationship of Axin-V5 and Wg with respect to the onset of Wg expression in c*–r*.