Fig. 1. Consequence of silencing nuclear β-catenin on mouse preimplantation embryo development.

(A, B) Immunofluorescence localization of total and dephospho (active) β-catenin in mouse preimplantation embryos. (C-F) Recombinant DKK1 protein (5 μg/ml) and PKF115-584 (0.1 μM) block nuclear import of active dephospho β-catenin and Cdx2 expression in preimplantation embryos, without interfering with the cellular level of total β-catenin and the development of 2-cell embryos to blastocysts in culture. Two-cell embryos recovered by flushing day 2 pregnant oviducts were cultured in groups of 5-10 in 25 μl of M16 medium under silicon oil in an atmosphere of 5% CO₂ and 95% air at 37□ for 72 h and the number of blastocysts developed was recorded. Experiments were repeated 3-5 times. The number above the bar in panel C indicates the number of blastocysts developed per the number of cultured 2-cell embryos. Images shown depict Cy3-labeled active β-catenin as red, SYTO-13-labeled nuclei as green and merge as yellow. Bar, 50 μm. ICM, inner cell mass; Tr, trophectoderm; veh: vehicle; PKF: PKF115-584.