title: Structure and functional properties of Norrin mimic Wnt for signalling with Frizzled4, Lrp5/6, and proteoglycan.
abstract: Wnt signalling regulates multiple processes including angiogenesis, inflammation, and tumorigenesis. Norrin (Norrie Disease Protein) is a cystine-knot like growth factor. Although unrelated to Wnt, Norrin activates the Wnt/β-catenin pathway. Signal complex formation involves Frizzled4 (Fz4), low-density lipoprotein receptor related protein 5/6 (Lrp5/6), Tetraspanin-12 and glycosaminoglycans (GAGs). Here, we report crystallographic and small-angle X-ray scattering analyses of Norrin in complex with Fz4 cysteine-rich domain (Fz4CRD), of this complex bound with GAG analogues, and of unliganded Norrin and Fz4CRD. Our structural, biophysical and cellular data, map Fz4 and putative Lrp5/6 binding sites to distinct patches on Norrin, and reveal a GAG binding site spanning Norrin and Fz4CRD. These results explain numerous disease-associated mutations. Comparison with the Xenopus Wnt8-mouse Fz8CRD complex reveals Norrin mimics Wnt for Frizzled recognition. The production and characterization of wild-type and mutant Norrins reported here open new avenues for the development of therapeutics to combat abnormal Norrin/Wnt signalling.
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Tao-Hsin
authors.initials: TH
authors.lastname: Chang
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Fu-Lien
authors.initials: FL
authors.lastname: Hsieh
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Matthias
authors.initials: M
authors.lastname: Zebisch
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Karl
authors.initials: K
authors.lastname: Harlos
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Elegheert
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: E Yvonne
authors.initials: EY
authors.lastname: Jones
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D005136:Eye Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051157:Frizzled Receptors / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D060492:Low Density Lipoprotein Receptor-Related Protein-5 / Q000378:metabolism; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D011509:Proteoglycans / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle
chemical_list: D005136:Eye Proteins; C402930:FZD4 protein, human; D051157:Frizzled Receptors; D060492:Low Density Lipoprotein Receptor-Related Protein-5; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555483:Lrp5 protein, mouse; C555476:Lrp6 protein, mouse; D050505:Mutant Proteins; C081848:NDP protein, human; D009419:Nerve Tissue Proteins; D011509:Proteoglycans
keywords: Wnt signalling; angiogenesis; biophysics; blood brain barrier; crystal structure; cystine-knot growth factor; developmental biology; human; mouse; retinal disease; stem cells; structural biology