R-spondin1 Is a High Affinity Ligand for LRP6 and Induces LRP6 Phosphorylation and β-Catenin Signaling Academic Article uri icon

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abstract

  • R-spondin proteins are newly identified secreted molecules that activate beta-catenin signaling. However, the mechanism of R-spondin action and its relationship with Wnt signaling remain unclear. Here we show that human R-spondin1 (hRspo1) is a high affinity ligand for the Wnt co-receptor LRP6 (K(d) = 1.2 nm). hRspo1 induces glycogen synthase kinase 3-dependent phosphorylation and activation of LRP6. DKK1, an LRP6 antagonist, inhibits hRspo1-induced LRP6 phosphorylation. We further demonstrate that hRspo1 synergizes with Frizzled5 in Xenopus axis induction assays and induces the phosphorylation of Dishevelled, a cytoplasmic component downstream of Frizzled function. Our study reveals interesting similarity and distinction between Wnt and R-spondin signaling.

authors

  • Wei, Qiou
  • Yokota, Chika
  • Semenov, Mikhail V
  • Doble, Bradley
  • Woodgett, Jim
  • He, Xi

publication date

  • May 25, 2007

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