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Pregnancy-specific glycoprotein 1 induces endothelial tubulogenesis through interaction with cell surface

Felipe A Lisboa1, James Warren, Gisela Sulkowski

  • 1Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.

The Journal of Biological Chemistry
|January 4, 2011
PubMed

Insights

Pregnancy-specific β1 glycoproteins (PSGs) bind to cell surface glycosaminoglycans (GAGs), identifying GAGs as key receptors. This interaction is crucial for PSG1

Area of Science:

  • Reproductive biology
  • Molecular and cell biology
  • Biochemistry

Background:

  • Pregnancy-specific β1 glycoproteins (PSGs) are abundant fetal proteins in maternal blood.
  • PSGs are secreted by the syncytiotrophoblast and may have immune modulatory and proangiogenic functions.
  • The cellular receptors for human PSGs are currently unknown.

Purpose of the Study:

  • To identify the cellular receptor for PSG1, the most highly expressed PSG member.
  • To investigate the role of glycosaminoglycans (GAGs) in PSG1 binding and function.

Main Methods:

  • Enzymatic and chemical removal of cell surface GAGs.
  • PSG1 binding assays on cells with depleted or absent GAGs.
  • Transfection of cells with specific GAG-binding proteins (syndecans, glypican-1).
  • Endothelial cell tube formation assays.

Main Results:

  • PSG1 binding was inhibited by GAG removal and heparin competition.
  • PSG1 did not bind to cells lacking heparan or chondroitin sulfate.
  • PSG1 binding was restored by syndecan and glypican-1 expression.
  • GAGs on endothelial cells are essential for PSG1-induced tube formation.

Conclusions:

  • Cell surface glycosaminoglycans (GAGs) function as receptors for PSG1.
  • The interaction between PSG1 and GAGs mediates PSG1's proangiogenic functions.
  • Identification of GAGs as PSG1 receptors provides insight into PSG functions during pregnancy.

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