G protein-dependent basal and evoked endothelial cell vWF secretion

Blood. 2014 Jan 16;123(3):442-50. doi: 10.1182/blood-2013-03-489351. Epub 2013 Sep 30.


von Willebrand factor (vWF) secretion by endothelial cells (ECs) is essential for hemostasis and thrombosis; however, the molecular mechanisms are poorly understood. Interestingly, we observed increased bleeding in EC-Gα13(-/-);Gα12(-/-) mice that could be normalized by infusion of human vWF. Blood from Gα12(-/-) mice exhibited significantly reduced vWF levels but normal vWF multimers and impaired laser-induced thrombus formation, indicating that Gα12 plays a prominent role in EC vWF secretion required for hemostasis and thrombosis. In isolated buffer-perfused mouse lungs, basal vWF levels were significantly reduced in Gα12(-/-), whereas thrombin-induced vWF secretion was defective in both EC-Gαq(-/-);Gα11(-/-) and Gα12(-/-) mice. Using siRNA in cultured human umbilical vein ECs and human pulmonary artery ECs, depletion of Gα12 and soluble N-ethylmaleimide-sensitive-fusion factor attachment protein α (α-SNAP), but not Gα13, inhibited both basal and thrombin-induced vWF secretion, whereas overexpression of activated Gα12 promoted vWF secretion. In Gαq, p115 RhoGEF, and RhoA-depleted human umbilical vein ECs, thrombin-induced vWF secretion was reduced by 40%, whereas basal secretion was unchanged. Finally, in vitro binding assays revealed that Gα12 N-terminal residues 10-15 mediated the binding of Gα12 to α-SNAP, and an engineered α-SNAP binding-domain minigene peptide blocked basal and evoked vWF secretion. Discovery of obligatory and complementary roles of Gα12 and Gαq/11 in basal vs evoked EC vWF secretion may provide promising new therapeutic strategies for treatment of thrombotic disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / chemistry
  • Endothelial Cells / cytology*
  • GTP-Binding Protein alpha Subunits, G12-G13 / metabolism*
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism*
  • Gene Expression Regulation
  • Hemostasis
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Mice
  • Mice, Knockout
  • Platelet Adhesiveness
  • Protein Binding
  • RNA, Small Interfering / metabolism
  • Signal Transduction
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / chemistry
  • Thrombosis
  • rhoA GTP-Binding Protein / metabolism*
  • von Willebrand Factor / metabolism*


  • Antibodies, Monoclonal
  • RNA, Small Interfering
  • Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
  • von Willebrand Factor
  • GTP-Binding Protein alpha Subunits, G12-G13
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • rhoA GTP-Binding Protein