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Kremen2 modulates Dickkopf2 activity during Wnt/LRP6 signaling
1Division of Molecular Embryology, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany.
Gene
|January 16, 2003
Summary
Kremen2 (Krm2) acts as a switch, modulating Dickkopf2 (Dkk2) activity in Wnt signaling. Krm2 transforms Dkk2 from a Wnt pathway activator to an inhibitor, impacting LRP6 signaling and embryonic development.
Area of Science:
- Molecular Biology
- Developmental Biology
- Cell Signaling
Background:
- Dickkopf1 (Dkk1) antagonizes Wnt/beta-catenin signaling by inhibiting LRP6.
- Dickkopf2 (Dkk2) exhibits context-dependent activity as an LRP6 agonist or antagonist.
- Kremen1 and Kremen2 (Krm2) are identified as high-affinity transmembrane receptors for Dkk proteins.
Purpose of the Study:
- To investigate the role of Kremen2 (Krm2) in regulating Dickkopf2 (Dkk2) activity.
- To elucidate the mechanism by which Krm2 modulates Wnt signaling pathways.
Main Methods:
- Transfection of human 293 fibroblasts with Dkk2 and Krm2.
- Analysis of Wnt/LRP6 and Wnt/Frizzled signaling.
- Xenopus embryo experiments to assess Wnt inhibition.
- Co-immunoprecipitation to identify Dkk-Krm2 interaction domains.
Main Results:
- Kremen2 (Krm2) blocks Dkk2-mediated LRP6 activation in fibroblasts.
- Krm2 enhances Dkk2's inhibition of Wnt/Frizzled signaling.
- Dkk2 and Krm2 cooperate to inhibit Wnt signaling in Xenopus embryos, causing anteriorization.
- Krm2 interacts with the second cysteine-rich domain of Dkk proteins.
Conclusions:
- Kremen2 (Krm2) functions as a critical regulator of Dkk2 activity.
- Krm2 switches Dkk2 from a Wnt/LRP6 signaling activator to an inhibitor.
- This interaction has implications for Wnt signaling modulation and embryonic development.