FIGURE 1:

A β-catenin knock-in reporter provides a faithful readout for Wnt activity in mESCs. (A) Endogenous β-catenin was tagged at the C-terminus with Venus and the histone protein H2B was tagged at the C-terminus with mTurquoise. Snapshots of a mESC harboring the β-catenin knock-in reporter show a gradual increase in the amount of β-catenin (yellow) in the nucleus (cyan). Images were taken over 5 h following stimulation with 5 nM Wnt3a. Scale bar, 10 μm. (B) Effective siRNA-mediated knockdown of Lrp6 was confirmed via Western blot. (C) Change in nuclear β-catenin upon stimulation with 5 nM Wnt3a was quantified. Lrp6 knockdown ablated nuclear translocation of β-catenin. Single β-catenin reporter mESCs were live imaged over 10 h (control siRNA, n = 23; Lrp6 siRNA, n = 22; no Wnt3a, n = 16).