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. 2004 Jun;24(11):4757–4768. doi: 10.1128/MCB.24.11.4757-4768.2004

FIG. 8.

FIG. 8.

Activated LRP6/Arrow can stabilize β-catenin/Armadillo without an apparent change in Dvl/Dsh phosphorylation. (A) A truncated form of Drosophila Arrow (ΔN-Arr) activates signaling to Armadillo (Arm) in S2 cells with no evidence of Dishevelled (Dsh) phosphorylation. Drosophila S2 cells were transiently transfected with control vector (lane 1), ΔN-Arr (lane 2), Dfrizzled2 (Dfz2; lane 3), or Dfz2 plus Wingless (Wg; lane 4). Cellular levels of Arm and phosphorylation of Dsh were analyzed by Western blotting, and β-tubulin provided a loading control. Dishevelled is constitutively phosphorylated in S2 cells stably transfected with Dfz2 (lane 5), allowing identification of two bands corresponding to phosphorylated Dsh. These lie below a nonspecific background band (labeled NS) in each lane. While Wg induces Arm stabilization and Dsh phosphorylation (lane 4), ΔN-Arr induces Arm stabilization only (lane 2). (B) ΔN-LRP6 causes stabilization of β-catenin but does not induce Dvl phosphorylation. 293T cells were transiently transfected with ΔN-LRP6, Wnt1, or control vector, in the presence or absence of Fzd8 Ex. Whole-cell and cytosolic extracts were analyzed for Dvl phosphorylation and β-catenin levels, respectively. Tubulin levels provided a loading control. Fzd8 Ex abolishes basal Dvl phosphorylation in all cases but does not prevent β-catenin stabilization in ΔN-LRP6-transfected cells.