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Crystal structures of the extracellular domain of LRP6 and its complex with DKK1

Nature Structural & Molecular Biology volume 18, pages 1204–1210 (2011)Cite this article

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Abstract

Low-density-lipoprotein (LDL) receptor-related proteins 5 and 6 (LRP5/6) are Wnt co-receptors essential for Wnt/β-catenin signaling. Dickkopf 1 (DKK1) inhibits Wnt signaling by interacting with the extracellular domains of LRP5/6 and is a drug target for multiple diseases. Here we present the crystal structures of a human LRP6-E3E4–DKK1 complex and the first and second halves of human LRP6's four propeller–epidermal growth factor (EGF) pairs (LRP6-E1E2 and LRP6-E3E4). Combined with EM analysis, these data demonstrate that LRP6-E1E2 and LRP6-E3E4 form two rigid structural blocks, with a short intervening hinge that restrains their relative orientation. The C-terminal domain of DKK1 (DKK1c) interacts with the top surface of the LRP6-E3 YWTD propeller and given their structural similarity, probably also that of the LRP6-E1 propeller, through conserved hydrophobic patches buttressed by a network of salt bridges and hydrogen bonds. Our work provides key insights for understanding LRP5/6 structure and the interaction of LRP5/6 with DKK, as well as for drug discovery.

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Figure 1: Crystal structure of LRP6-E1E2.
Figure 2: Crystal structure of LRP6-E3E4.
Figure 3: Rigidity of the two LRP6-ECD structural blocks and the hinge between them.
Figure 4: Crystal structure of the LRP6-E3E4–DKK1c complex.
Figure 5: Specific interactions in the two LRP6-E3–DKK1c interfaces.
Figure 6: DKK1 residues in the DKK1-LRP5/6 interface are important for its inhibitory effects on Wnt/β-catenin signaling.

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Acknowledgements

We are grateful to the staff at ALS beamlines BL 8.2.1 and 8.2.2 for assistance with synchrotron data collection. We thank G. Bu (Washington University) for human LRP6 cDNA. This work was supported by US National Institutes of Health (NIH) grants CA90351 to W.X. R.T.M. is funded by the Howard Hughes Medical Institute. T.B. was supported by a Training Grant from NIH/National Institute of Arthritis and Musculoskeletal and Skin (T32AR056969).

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  1. Zhiyi Wei

    Present address: Present address: Division of Life Science, Hong Kong University of Science and Technology, Hong Kong.,

Authors and Affiliations

  1. Department of Biological Structure, University of Washington School of Medicine, Seattle, Washington, USA

    Zhihong Cheng, Zhiyi Wei, Seamus Morrone, Liguo Wang & Wenqing Xu

  2. Department of Pharmacology, Howard Hughes Medical Institute, University of Washington School of Medicine, Seattle, Washington, USA

    Travis Biechele & Randall T Moon

  3. Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, Washington, USA

    Travis Biechele & Randall T Moon

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Contributions

Z.C., T.B., R.T.M., L.W. and W.X. participated in the experimental design and wrote the paper. Z.C. did protein purification, crystallization, crystal structural determination, Alpha Technology binding assay, size-exclusion chromatography and dynamic light scattering analysis. T.B. did the β-catenin activated reporter assay. Z.W. developed protein expression systems. L.W. did EM analysis. S.M. provided technical support.

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Correspondence to Wenqing Xu.

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R.T.M. is a cofounder of, and consultant with, FATE Therapeutics. The other authors declare no competing financial interests.

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Cheng, Z., Biechele, T., Wei, Z. et al. Crystal structures of the extracellular domain of LRP6 and its complex with DKK1. Nat Struct Mol Biol 18, 1204–1210 (2011). https://doi.org/10.1038/nsmb.2139

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