Figure 6
From: Insulin-like factor regulates neural induction through an IGF1 receptor-independent mechanism
Insulin3 inhibits Wnt signalling but cannot activate the IGF1 receptor.
mRNAs were injected into the animal pole of both blastomeres at the two-cell stage in X. laevis embryos. (a) One ng of insulin3, IGF1, or IGF1R mRNA was injected per embryo. Embryos were harvested at stage 11 for western blot analysis. (b) One ng of Myc-tagged extracellular domain of IGF1 receptor (IGF1Rex-Myc), IGF1-HA, insulin3-HA, or insulin1-HA mRNA was injected per embryo. Embryos were harvested at stage 10.5 for co-immunoprecipitation assay. (c,d,e) Amounts of mRNA injected per embryos were: (c) FGF4 (10 pg), (d) insulin3 (100 pg) and (e) IGF1 (100 pg). Animal caps were dissected at stage 9 and treated with chemical MEK inhibitors, PD98059 (100 μM) and U0126 (100 μM) until sibling embryos reached stage 10.5. (c) Bra expression induced by FGF4 was inhibited, but otx2 expression induced by (d) insulin3 or (e) IGF1 was not. Full-length blots and gels are presented in Supplementary figure S8.
