Sonic hedgehog signaling defect in <i>Wdpcp^Cys40</i> mutant.

<p>(A–F) In-situ hybridization of E10.5 forelimbs shows <i>Wdpcp^Cys40</i> mutants with expanded expression of <i>Fgf4</i> in the AER (apical ectodermal ridge) (A, B) and <i>Gremlin</i> in the limb mesenchyme (C, D), but reduced expression of <i>Ptch1</i> (E, F and asterisk in F). In (A) and (B), black arrowheads indicate the span of the AER, and white arrowheads are the anterior and posterior bases of the limb bud. (G–J) <i>Wdpcp</i> deficiency rescued the severe defect phenotypes of <i>Smo</i>^−/− (G) and <i>Ptch1</i>^−/− (I) mutant embryos at E10.5 dpc. The <i>Wdpcp^Cys40/Cys40</i>;<i>Smo</i>^−/− (H) and <i>Wdpcp^Cys40/Cys40;Ptch1</i>^−/− (J) double homozygous mutant embryos collected at E10.5 dpc show more robust growth with better axial development and also more normal head and heart development. (K) Western blotting of Gli3 in tissue extracts obtained from the limb and neural tube shows a decrease of Gli3-R/Gli3-FL ratio in <i>Wdpcp^Cys40</i> mutant embryos. Scale bars, 200 µm in (A), 1 mm in (G). Scales are the same in (A–F) and (G–J).