title: Targeting of bone morphogenetic protein growth factor complexes to fibrillin.
abstract: Both latent transforming growth factor-beta (TGF-beta)-binding proteins fibrillins are components of microfibril networks, and both interact with members of the TGF-beta family of growth factors. Interactions between latent TGF-beta-binding protein-1 and TGF-beta and between fibrillin-1 and bone morphogenetic protein-7 (BMP-7) are mediated by the prodomain of growth factor complexes. To extend this information, investigations were performed to test whether stable complexes are formed by additional selected TGF-beta family members. Using velocity sedimentation in sucrose gradients as an assay, complex formation was demonstrated for BMP-7 and growth and differentiation factor-8 (GDF-8), which are known to exist in prodomain/growth factor complexes. Comparison of these results with complex formation by BMP-2, BMP-4 (full-length and shortened propeptides), BMP-10, and GDF-5 allowed us to conclude that all, except for BMP-2 and the short BMP-4 propeptides, formed complexes with their growth factors. Using surface plasmon resonance, binding affinities between fibrillin and all propeptides were determined. Binding studies revealed that the N-terminal end of fibrillin-1 serves as a universal high affinity docking site for the propeptides of BMP-2, -4, -7, and -10 and GDF-5, but not GDF-8, and located the BMP/GDF binding site within the N-terminal domain in fibrillin-1. Rotary shadowing electron microscopy of molecules of BMP-7 complex bound to fibrillin-1 confirmed these findings and also showed that prodomain binding targets the growth factor to fibrillin. Immunolocalization of BMP-4 demonstrated fibrillar staining limited to certain tissues, indicating tissue-specific targeting of BMP-4. These data implicate the fibrillin microfibril network in the extracellular control of BMP signaling and demonstrate differences in how prodomains target their growth factors to the extracellular space.
authors.affiliation: Shriners Hospital for Children, Portland, Oregon 97239, USA.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Sengle
authors.forename: Noe L
authors.initials: NL
authors.lastname: Charbonneau
authors.forename: Robert N
authors.initials: RN
authors.lastname: Ono
authors.forename: Takako
authors.initials: T
authors.lastname: Sasaki
authors.forename: Jennifer
authors.initials: J
authors.lastname: Alvarez
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Keene
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Bächinger
authors.forename: Lynn Y
authors.initials: LY
authors.lastname: Sakai
mesh_terms: D001483:Base Sequence; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D017931:DNA Primers / Q000737:chemistry; D000071838:Fibrillin-1; D000071837:Fibrillins; D055428:Growth Differentiation Factor 5; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D015398:Signal Transduction; D020349:Surface Plasmon Resonance; D016212:Transforming Growth Factor beta / Q000378:metabolism; D054392:Adipokines
chemical_list: D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D000071838:Fibrillin-1; D000071837:Fibrillins; D055428:Growth Differentiation Factor 5; D036341:Intercellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D016212:Transforming Growth Factor beta; C525718:BMP2 protein, human; C525819:BMP7 protein, human; C000605722:FBN1 protein, human; D054392:Adipokines; C525893:GDF5 protein, human