Fig. 9: Anterior migration defects of mesendoderm cells of Usp39 mutant embryos are restored by removal of one copy of the Ube1 gene.

a–c Immunohistochemistry of EOMESDERMIN (extra-embryonic ectoderm, visceral endoderm, and primitive streak marker) at E6.75 of wild-type (a), Usp39^−/− (b), and Usp39^−/−;Ube1^+/− (c) embryos. d–l Whole-mount in situ hybridization of Hex and Foxa2 in wild-type (d,g,j), Usp39^−/− (e, h, k), and Usp39^−/−; Ube1^+/− (f, i, l) embryos, and corresponding sagittal sections (j–l) are shown at E7.5. In the Usp39^−/− embryos, Hex and Foxa2 positive mesendoderm cells remained on the distal side (e, h, k dotted curved lines). The anterior movement of mesendoderm cells was partially restored in Usp39^−/−; Ube1^+/− embryos (f, i, l; arrowheads). m A schematic illustration of ectoderm and primitive streak regions after removal of the visceral endoderm layer at E6.5. n PRICKLE1 protein was detected in the migrating primitive streak (ps), rather than in ectoderm (ect) at E6.5. PRICKLE1 (magenta) and 4,6′-diamidino-2-phenylindole (DAPI; blue). o–r PRICKLE1 protein was downregulated by Dicer-substrate small interfering (Dsi) RNA of Usp39 in MCF7 cells. PRICKLE1 (magenta) and DAPI (green). ame anterior mesendoderm, ect ectoderm, eex extra-embryonic ectoderm, nc notochord, ps primitive streak. Scale bars represent 10 μm (p, r), 50 μm (a–c, o, q) and 100 μm (n), and 200 μm (d–i).