Wnt signaling decreases the expression of Tcf3 and increases that of Tcf1 and Lef1 containing β-catenin binding domain.

<p><b><i>A–B</i></b>, E11.5 NPCs were incubated in the presence of FGF2 with control, recombinant Wnt3a (<b><i>A</i></b>) or CHIR99021 (<b><i>B</i></b>) for 0, 3 or 6 h. The mRNA levels of Tcf3, Tcf4, Tcf1 (1st-2nd exon shown in <b><i>E</i></b>) and Lef1 (1st-2nd exon shown in <b><i>E</i></b>) were determined by qPCR analysis. Data are normalized with GAPDH mRNA (arbitrary unit) and represent the mean of three independent samples ± SD. <b><i>C</i></b>, E11.5 NPCs were incubated in the presence of FGF2 with control or recombinant Wnt3a for 24 h. Cell lysates were subjected to Western blotting analysis with antibodies to Tcf3 and GAPDH. <b><i>D</i></b>, E11.5 NPCs were incubated in the presence of FGF2 with control or CHIR99021 for 0, 3 or 6 h. The mRNA levels of Tcf3-l and Tcf3-s were determined by qPCR analysis as <b><i>B</i></b>. <b><i>E–F’</i></b>, E11.5 NPCs were incubated in the presence of FGF2 with control or recombinant Wnt3a for 4 h. Poly-A selected RNA was subjected to Northern blotting analysis with Tcf1 or Lef1 domain specific probes shown in <b><i>E</i></b>. <b><i>F,F’</i></b>, Markers represent 28S (upper) and 18S (lower) ribosomal RNA. Ethidium bromide (EtBr) staining is shown as loading control (lower panel).