Fig. 4.

Control of sfrp-1 expression by the Wnt signaling network governing ANE restriction. A Fzl5/8–JNK signal-mediated downregulation of ANE gene expression is enhanced in the absence of Fzl1/2/7. Control embryos showing sfrp-1 expression at 60-cell (a), blastula (b) and mesenchyme blastula stage (c). Ad–f In Fzl1/2/7 MO injected embryos, sfrp-1 is expressed at the 60-cell stage (d), but downregulated in blastula (e) and mesenchyme blastula embryos (f). Ba–c sfrp-1 expression in Fzl1/2/7 morphants is rescued by overexpressing dkk1 mRNA. The number of embryos examined that show the representative phenotypes depicted is indicated in each panel. C A model diagram, showing that maternal sFRP-1 works together with, but independently from, Fzl1/2/7 signaling during the early stages of ANE restriction (Ca) and that zygotic sfrp-1 is part of the ANE GRN downregulated by Wnt/JNK signaling during later stages of the process (Cb). The model also shows that during later stages of ANE restriction the Fzl5/8 receptor is a member of the ANE GRN and Fzl5/8–JNK signaling downregulates fzl5/8 expression in the lateral ectoderm. The model is based on the data presented in this and the preceding figures, as well as data from [20]. MO, morpholino. Scale bar = 20 μm