title: Pregnancy-specific glycoprotein 1 induces endothelial tubulogenesis through interaction with cell surface proteoglycans.
abstract: Pregnancy-specific β1 glycoproteins (PSGs) are the most abundant fetal proteins in the maternal bloodstream in late pregnancy. They are secreted by the syncytiotrophoblast and are detected around day 14 postfertilization. There are 11 human PSG genes, which encode a family of proteins exhibiting significant conservation at the amino acid level. We and others have proposed that PSGs have an immune modulatory function. In addition, we recently postulated that they are proangiogenic due to their ability to induce the secretion of VEGF-A and the formation of tubes by endothelial cells. The cellular receptor(s) for human PSGs remain unknown. Therefore, we conducted these studies to identify the receptor for PSG1, the highest expressed member of the family. We show that removal of cell surface glycosaminoglycans (GAGs) by enzymatic or chemical treatment of cells or competition with heparin completely inhibited binding of PSG1. In addition, PSG1 did not bind to cells lacking heparan or chondroitin sulfate on their surface, and binding was restored upon transfection with all four syndecans and glypican-1. Importantly, the presence of GAGs on the surface of endothelial cells was required for the ability of PSG1 to induce tube formation. This finding indicates that the PSG1-GAG interaction mediates at least some of the PSG1 proposed functions.
authors.affiliation: Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Lisboa
authors.forename: James
authors.initials: J
authors.lastname: Warren
authors.forename: Gisela
authors.initials: G
authors.lastname: Sulkowski
authors.forename: Marta
authors.initials: M
authors.lastname: Aparicio
authors.forename: Guido
authors.initials: G
authors.lastname: David
authors.forename: Enrique
authors.initials: E
authors.lastname: Zudaire
authors.forename: Gabriela S
authors.initials: GS
authors.lastname: Dveksler
mesh_terms: D000818:Animals; D016466:CHO Cells; D002809:Chondroitin Sulfates / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006493:Heparin / Q000378:metabolism; D006497:Heparan Sulfate / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D041681:NIH 3T3 Cells; D018919:Neovascularization, Physiologic / Q000502:physiology; D011247:Pregnancy; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D053667:Syndecans / Q000378:metabolism; D014162:Transfection; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
chemical_list: D002809:Chondroitin Sulfates; D006493:Heparin; D006497:Heparan Sulfate; D011268:Pregnancy-Specific beta 1-Glycoproteins; D011956:Receptors, Cell Surface; D053667:Syndecans