title: Modulation of GDF5/BRI-b signalling through interaction with the tyrosine kinase receptor Ror2.
abstract: The brachydactylies are a group of inherited disorders of the hands characterized by shortened digits. Mutations in the tyrosine kinase receptor Ror2 cause brachydactyly type B (BDB). Mutations in GDF5, a member of the BMP/TGF-beta ligand family, cause brachydactyly type C (BDC) whereas mutations in the receptor for GDF5, BRI-b, cause brachydactyly type A2 (BDA2). There is considerable degree of phenotypic overlap between the subtypes BDB, BDC and BDA2. Here we demonstrate that all three components are involved in GDF5 induced regulation of chondrogenesis. We show that Ror2 (tyrosine kinase receptor) and BRI-b (serine/threonine kinase receptor) form a ligand independent heteromeric complex. The frizzled-like-CRD domain of Ror2 is required for this complex. Within that complex Ror2 gets transphosphorylated by BRI-b. We show that Ror2 modulates GDF5 signalling by inhibition of Smad1/5 signalling and by activating a Smad-independent pathway. Both pathways however, are needed for chondrogenic differentiation as demonstrated in ATDC5 cells. The functional interaction of Ror2 with GDF5 and BRI-b was genetically confirmed by the presence of epistatic effects in crosses of Ror2, BRI-b and Gdf5 deficient mice. These results indicate for the first time a direct interaction of Ser/Thr- and Tyr-Kinase receptors and provide evidence for modulation of the Smad-pathway and GDF5 triggered chondrogenesis.
authors.affiliation: Department of Physiological Chemistry, Biocenter, University of Würzburg, Germany.
authors.forename: Marei
authors.initials: M
authors.lastname: Sammar
authors.forename: Sigmar
authors.initials: S
authors.lastname: Stricker
authors.forename: Georg C
authors.initials: GC
authors.lastname: Schwabe
authors.forename: Christina
authors.initials: C
authors.lastname: Sieber
authors.forename: Anke
authors.initials: A
authors.lastname: Hartung
authors.forename: Michael
authors.initials: M
authors.lastname: Hanke
authors.forename: Isao
authors.initials: I
authors.lastname: Oishi
authors.forename: Jens
authors.initials: J
authors.lastname: Pohl
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Minami
authors.forename: Walter
authors.initials: W
authors.lastname: Sebald
authors.forename: Stefan
authors.initials: S
authors.lastname: Mundlos
authors.forename: Petra
authors.initials: P
authors.lastname: Knaus
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D019556:COS Cells; D002460:Cell Line; D020219:Chondrogenesis; D004268:DNA-Binding Proteins / Q000378:metabolism; D005838:Genotype; D006025:Glycosaminoglycans / Q000096:biosynthesis; D055428:Growth Differentiation Factor 5; D006801:Humans; D006811:Humerus / Q000737:chemistry; D008024:Ligands; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D057050:Receptor Tyrosine Kinase-like Orphan Receptors; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051785:Smad Proteins; D051898:Smad1 Protein; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C525893:GDF5 protein, human; C525894:Gdf5 protein, mouse; D006025:Glycosaminoglycans; D055428:Growth Differentiation Factor 5; D008024:Ligands; D011956:Receptors, Cell Surface; C497399:SMAD1 protein, human; D051785:Smad Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D015534:Trans-Activators; C078717:ROR2 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D057050:Receptor Tyrosine Kinase-like Orphan Receptors; C477010:Ror2 protein, mouse; D017346:Protein Serine-Threonine Kinases