@article{b39aba5bdb4c4c8aaa7e2d5b579b93fd,
title = "Structure of Stem Cell Growth Factor R-spondin 1 in Complex with the Ectodomain of Its Receptor LGR5",
abstract = "Leucine-rich repeat-containing G protein-coupled receptors 4-6 (LGR4-LGR6) are receptors for R-spondins, potent Wnt agonists that exert profound trophic effects on Wnt-driven stem cells compartments. We present crystal structures of a signaling-competent fragment of R-spondin 1 (Rspo1) at a resolution of 2.0{\AA} and its complex with the LGR5 ectodomain at a resolution of 3.2{\AA}. Ecto-LGR5 binds Rspo1 at its concave leucine-rich-repeat (LRR) surface, forming a dimeric 2:2 complex. Fully conserved residues on LGR4-LGR6 explain promiscuous binding of R-spondins. A phenylalanine clamp formed by Rspo1 Phe106 and Phe110 pinches Ala190 of LGR5 and is critical for binding. Mutations related to congenital anonychia reduce signaling, but not bindingof Rspo1 to LGR5. Furthermore, antibody binding to the extended loop of the C-terminal LRR cap of LGR5 activates signaling in a ligand-independent manner. Thus, our data reveal binding of R-spondins to conserved sites on LGR4-LGR6 and, in analogy to FSHR and related receptors, suggest a direct signaling role for LGR4-LGR6 in addition to its formation of Wnt receptor and coreceptor complexes. {\textcopyright} 2013 The Authors.",
author = "Peng, {Weng Chuan} and Wim deLau and Federico Forneris and Granneman, {Joke C.M.} and Meritxell Huch and Hans Clevers and Piet Gros",
note = "Funding Information: We gratefully thank B.T. Burnley, E.G. Huizinga, P.K. Madoori, A.M.M. Schreurs, T. Tenic, H. Teunissen, and M. van de Wetering for discussions and assistance and J. Aho (R&D Systems) for generously providing antibodies. We thank the ESRF and the SLS for the provision of synchrotron radiation facilities and beamline scientists of the SLS, ESRF, and the European Molecular Biology Laboratory for assistance. Financial support was provided by the Netherlands Organization for Scientific Research (NWO-CW grant no. 700.57.010; ZonMW/NGI/Pre-seed grant no. 936.1001), Koningin Wilhelmina Fonds (PF-HUBR 2007-3956), the European Research Council (Advanced Grant no. 233229), and the European Commission{\textquoteright}s Seventh Framework Programme (FP7/2007-2013) under BioStruct-X (grant no. 283570). W.C.P. performed cloning, expression, purification, crystallization, data collection, structure determination, and refinement. W.d.L. performed cloning; initiated antibody studies, anonychia-related mutations, and chimeric LGR5-GPA33 experiments; and performed signaling assays and immunoprecipitations. M.H. performed intestinal organoid experiments. F.F. performed data collection, structure determination, and refinement and prepared figures. J.C.M.G. performed cloning. W.C.P., W.d.L., F.F., H.C., and P.G. discussed results and wrote the paper. H.C. and P.G. supervised the project. ",
year = "2013",
month = mar,
day = "27",
doi = "10.1016/j.celrep.2013.06.009",
language = "English",
volume = "3",
pages = "1885--1892",
journal = "Cell reports",
issn = "2211-1247",
publisher = "Cell Press",
number = "6",
}