Angiopoietin-3 is tethered on the cell surface via heparan sulfate proteoglycans.
Angiopoietins are a family of factors that play important roles in angiogenesis, and their receptor, Tie-2 receptor tyrosine kinase, is expressed primarily by endothelial cells. Three angiopoietins have been identified so far, angiopoietin-1 (Ang-1), angiopietin-2 (Ang-2), and angiopoietin-3 (Ang-3). It has been established that Ang-1 and Tie-2 play essential roles in embryonic angiogenesis. We have demonstrated recently that, unlike Ang-2, Ang-1 binds to the extracellular matrix, which regulates the availability and activity of Ang-1 (Xu, Y., and Yu, Q. (2001) J. Biol. Chem. 276, 34990-34998). However, the role and biochemical characteristics of Ang-3 are unknown. In our current study, we demonstrated that, unlike Ang-1 and Ang-2, Ang-3 is tethered on cell surface via heparan sulfate proteoglycans (HSPGs), especially perlecan. The cell surface-bound Ang-3 is capable of binding to its receptor, Tie-2; suggesting HSPGs concentrate Ang-3 on the cell surface and present Ang-3 to its receptor to elicit specific local reaction. Mutagenesis experiment revealed that the coiled-coil domain of Ang-3 is responsible for its binding to the cell surface. In addition, we demonstrated that the cell surface-bound Ang-3 but not soluble Ang-3 induces retraction and loss of integrity of endothelial monolayer, indicating the binding of Ang-3 to the cell surface via HSPGs is required for this bioactivity of Ang-3.
Xu
Yin
Y
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Liu
Yao-Juan
YJ
Yu
Qin
Q
D042683:Angiopoietin-1 / Q000378:metabolism; D042702:Angiopoietin-2 / Q000378:metabolism; D000091304:Angiopoietin-Like Protein 1; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002417:Cattle; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D005109:Extracellular Matrix / Q000378:metabolism; D017353:Gene Deletion; D019812:Heparan Sulfate Proteoglycans / Q000737:chemistry* / Q000378:metabolism; D006497:Heparan Sulfate / Q000737:chemistry; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology*; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D009130:Muscle, Smooth / Q000378:metabolism; D016296:Mutagenesis; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000378:metabolism; D042787:Receptor, TIE-2 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053667:Syndecans; D014162:Transfection
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D000091304:Angiopoietin-Like Protein 1; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins; D000939:Epitopes; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D011509:Proteoglycans; D042787:Receptor, TIE-2; D011993:Recombinant Fusion Proteins; D053667:Syndecans; C117578:ANGPTL1 protein, human