title: Heparan sulfate is required for bone morphogenetic protein-7 signaling.
abstract: Although genetic studies have suggested that heparan sulfate (HS) is involved in bone morphogenetic protein (BMP)-mediated embryonic morphogenesis, it is unclear whether HS is directly involved in BMP-mediated signaling. Here, we investigate the involvement of HS in BMP-7 signaling. We show that HS and heparin chains specifically bind to BMP-7. Digestion of cell-surface HS with heparitinase interferes with BMP-7-mediated Smad phosphorylation in ROS 17/2.8 osteoblastic cells. Inhibiting sulfation of cell-surface HS with chlorate also causes interruption of Smad phosphorylation. Addition of exogenous heparin to ROS 17/2.8 cells prevents BMP-7-mediated Smad phosphorylation rather than enhances the BMP-7 signal, suggesting that HS should be anchored on the plasma membrane for BMP signaling. Moreover, BMP-7 binding to ROS 17/2.8 cells is inhibited by chlorate treatment and exogenous application of heparin. These results demonstrate that BMP-7 specifically binds to cell-surface HS and the BMP-7-HS interaction is required for BMP-7 signaling.
authors.affiliation: The Tokyo Metropolitan Institute of Medical Science, Department of Biochemical Cell Research, Bunkyo-ku, Tokyo 113-8613, Japan. irie@rinshoken.or.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Irie
authors.forename: Hiroko
authors.initials: H
authors.lastname: Habuchi
authors.forename: Koji
authors.initials: K
authors.lastname: Kimata
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sanai
mesh_terms: D000818:Animals; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002713:Chlorine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006025:Glycosaminoglycans / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006497:Heparan Sulfate / Q000378:metabolism*; D015151:Immunoblotting; D008956:Models, Chemical; D010006:Osteoblasts; D010766:Phosphorylation; D011133:Polysaccharide-Lyases / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012685:Sepharose / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta; D014407:Tumor Cells, Cultured
chemical_list: D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D002713:Chlorine; D006025:Glycosaminoglycans; D006493:Heparin; D006497:Heparan Sulfate; D011133:Polysaccharide-Lyases; D012685:Sepharose; D016212:Transforming Growth Factor beta; C525821:Bmp7 protein, rat; C021349:heparitinsulfate lyase