Histidine-proline rich glycoprotein (HPRG) binds and transduces anti-angiogenic signals through cell surface tropomyosin on endothelial cells

• Published in: Thrombosis and haemostasis Vol. 92; no. 2; p. 403
• Main Authors: Guan, Xiaojun, Juarez, Jose C, Qi, Xiaoping, Shipulina, Natalya V, Shaw, David E, Morgan, William T, McCrae, Keith R, Mazar, Andrew P, Doñate, Fernando
• Format: Journal Article
• Language: English
• Published: Germany 01.08.2004
• Subjects: Angiogenesis Inhibitors - pharmacology; Animals; Apoptosis; Binding Sites; Biotinylation; Cell Membrane - metabolism; Cell Proliferation; Cells, Cultured; Chickens; Collagen - pharmacology; Dose-Response Relationship, Drug; Drug Combinations; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Endothelium, Vascular - pathology; Fibroblast Growth Factor 2 - metabolism; Heparan Sulfate Proteoglycans - metabolism; Humans; Hydrogen-Ion Concentration; Kinetics; Kininogens - chemistry; Laminin - pharmacology; Neovascularization, Pathologic; Peptides - chemistry; Protein Binding; Protein Structure, Tertiary; Protein Transport; Proteins - metabolism; Proteins - physiology; Proteoglycans - pharmacology; Rabbits; Time Factors; Tropomyosin - chemistry; Umbilical Veins - cytology; Zinc - chemistry
• ISSN: 0340-6245
• DOI: 10.1160/TH04-02-0073

The anti-angiogenic properties of the histidine-proline-rich (H/P) domain of HPRG have recently been described (Juarez JC, et al. Cancer Research 2002; 62: 5344-50). However, the binding site that mediates these properties is unknown. HPRG is evolutionarily, functionally and structurally related to cleaved high molecular weight kininogen (HKa), an anti-angiogenic polypeptide that stimulates apoptosis of proliferating endothelial cells through binding to cell-surface tropomyosin (Zhang J-C, et al. Proc Natl Acad Sci USA 2002; 99: 12224-9). In this study, we demonstrate that HPRG binds with high affinity to FGF-2-stimulated human umbilical vein endothelial cells (HUVEC) and immobilized tropomyosin in a Zn2+ or pH-dependent manner, and that this interaction is mediated by the H/P domain of HPRG. At least two binding sites for HPRG, tropomyosin and heparan sulfate proteoglycans (HSPs), were identified on the surface of FGF-2-activated endothelial cells. Translocation of tropomyosin to the surface of HUVEC occurred in response to FGF-2, and the anti-angiogenic activity of HPRG in a Matrigel plug model was partially inhibited by soluble tropomyosin. These results suggest that HPRG binds to endothelial cell surface tropomyosin which at least partially mediates the antiangiogenic effects of HPRG.