Synthetic peptides bind to high-affinity thrombin receptors and modulate thrombin mitogenesis.
Initiation of cell proliferation by thrombin requires signals generated by thrombin interaction with specific high-affinity receptors and thrombin enzymic activity. Using synthetic peptides representing various domains of thrombin, we have identified a region adjacent to the proteolytic pocket of thrombin which confers high-affinity binding and generation of mitogenic signals. One peptide, representing residues 508 to 530 of human prothrombin (p508-530), inhibits up to 70% of the specific binding of 125I-alpha-thrombin at concentrations of less than 100 nM, enhances the ability of thrombin to stimulate DNA synthesis and stimulates DNA synthesis in cells treated with 25 ng/ml phorbol myristate acetate (PMA). Thus, this peptide or a portion of this peptide appears to represent the high-affinity receptor binding domain of thrombin. In contrast to the 23 amino acid peptide (p508-530), the tetrapeptide RGDA (p517-520) contained in this region competes for 125I-thrombin binding at concentrations from 100 to 2000 nM, but inhibits rather than stimulates the mitogenic effects of alpha-thrombin. Non-homologous peptides, or fibronectin-specific peptides (such as RGDS or GRGDSP) do not compete for 125I-alpha-thrombin binding and have no effect on thrombin mitogenesis. These studies demonstrate that peptides representing portions of the binding domain of thrombin: i) can generate receptor-occupancy related signals that enhance thrombin mitogenesis and are themselves mitogenic in cells treated with PMA; or ii) in the case of RGDA (which may be too small to generate signals), can act as antagonists, inhibiting the mitogenic effects of thrombin by preventing thrombin-receptor interaction.
Glenn
K C
KC
Monsanto Corporation.
Frost
G H
GH
Bergmann
J S
JS
Carney
D H
DH
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology; D011487:Protein Conformation; D011516:Prothrombin / Q000378:metabolism* / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018179:Receptors, Thrombin; D012689:Sequence Homology, Nucleic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D005353:Fibronectins; D009842:Oligopeptides; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D011516:Prothrombin; C058161:glycyl-arginyl-glycyl-aspartyl-seryl-proline; C075872:arginyl-glycyl-aspartyl-alanine; C046617:arginyl-glycyl-aspartyl-serine; D013755:Tetradecanoylphorbol Acetate