Trimer Carboxyl Propeptide of Collagen I Produced by Mature Osteoblasts Is Chemotactic for Endothelial Cells

• Published in: The Journal of biological chemistry 2000-10, Vol.275 (42), p.32658-32663
• Main Authors: Palmieri, Daniela, Camardella, Laura, Ulivi, Valentina, Guasco, Gaetana, Manduca, Paola
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies - pharmacology; Bone Morphogenetic Protein 1; Bone Morphogenetic Proteins - metabolism; Cell Line; Cells, Cultured; Chemotaxis - drug effects; Collagen - biosynthesis; Collagen - chemistry; Collagen - physiology; Culture Media, Conditioned; Dogs; Endothelium, Vascular - cytology; Endothelium, Vascular - physiology; Hepatocyte Growth Factor - pharmacology; Humans; Kidney; Metalloendopeptidases - metabolism; Molecular Sequence Data; Osteoblasts - cytology; Osteoblasts - physiology; Osteogenesis; Phosphopeptides - biosynthesis; Phosphopeptides - chemistry; Phosphopeptides - physiology; Procollagen; Rats
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M002698200

During the second phase of osteogenesis in vitro, rat osteoblasts secrete inducer(s) of chemotaxis and chemoinvasion of endothelial and tumor cells. We report here the characterization and purification from mature osteoblast conditioned medium of the agent chemotactic for endothelial cells. The chemoactive conditioned medium specifically induces directional migration of endothelial cells, not affecting the expression and activation of gelatinases, cell proliferation, and scattering. Directional migration induced in endothelial cells by conditioned medium from osteoblasts is inhibited by pertussis toxin, by blocking antibodies to integrins α1, β1, and β3, and by antibodies to metalloproteinase 2 and 9. The biologically active purified protein has two sequences, coincident with the amino-terminal amino acids, respectively, of the α1 and of the α2 carboxyl propeptides of type I collagen, as physiologically produced by procollagen C proteinase. Antibodies to type I collagen and to the carboxyl terminus of α1or α2 chains inhibit chemotaxis. The chemoattractant is the propeptide trimer carboxyl-terminal to type I collagen, and its activity is lost upon reduction. These data illustrate a previously unknown function for the carboxyl-terminal trimer, possibly relevant in promoting endothelial cell migration and vascularization of tissues producing collagen type I.