Protein kinase C-δ mediates von Willebrand factor secretion from endothelial cells in response to vascular endothelial growth factor (VEGF) but not histamine

Abstract

Summary. Background: Vascular endothelial growth factor (VEGF) and histamine induce von Willebrand factor (VWF) release from vascular endothelial cells. Protein kinase C (PKC) is involved in the control of exocytosis in many secretory cell types. Objectives: We investigated the role of PKC and the interactions between PKC and Ca2+ signaling in both VEGF‐induced and histamine‐induced VWF secretion from human umbilical vein endothelial cells (HUVECs). Results: Several PKC inhibitors (staurosporine, Ro31‐8220, myristoylated PKC peptide inhibitor and Go6983) block VEGF‐induced but not histamine‐induced VWF secretion. PKC‐α and novel PKCs (PKC‐δ, PKC‐ε, and PKC‐η), but not PKC‐β, are expressed in HUVECs. Both VEGF and histamine activate PKC‐δ. However, gene inactivation experiments using small interfering RNA indicate that PKC‐δ (but not PKC‐α) is involved in the regulation of VEGF‐induced but not histamine‐induced secretion. Both VEGF and histamine induce a rise in cytosolic free Ca2+ ([Ca2+]c), but the response to VEGF is weaker and even absent in a significant subset of cells. Furthermore, VEGF‐induced secretion is largely preserved when the rise in [Ca2+]c is prevented by BAPTA‐AM. Conclusions: Our study identifies striking agonist specificities in signal–secretion coupling. Histamine‐induced secretion is dependent on [Ca2+]c but not PKC, whereas VEGF‐induced secretion is largely dependent on PKC‐δ and significantly less on [Ca2+]c. Our data firmly establish the key role of PKC‐δ in VEGF‐induced VWF release, but suggest that a third, VEGF‐specific, signaling intermediate is required as a PKC‐δ coactivator.

Hypertensive stretch regulates endothelial exocytosis of Weibel-Palade bodies through VEGF receptor 2 signaling pathways

“…VEGFR2 is expressed in both venous and arterial ECs. In addition, recent studies, including ours, have shown that VEGF induces WPB exocytosis in both arterial and venous ECs primarily mediated by VEGFR2 [18,19,29]. Therefore, it is not unexpected that stretch exerts a proexocytosis effect on both arteries and veins.…”

Clinical and prognostic implications of low or high level of von Willebrand factor in patients with Waldenström macroglobulinemia

“…[33][34][35][36][37] Histamine and VEGF have been reported to be involved in VWF exocytosis also. [8][9][10] Finally, inflammatory parameters were slightly albeit nonsignificantly increased in patients with high VWF:Ag (whereas those parameters had no significant independent prognostic value for subsequent outcome; data not shown). An adverse prognostic effect of very high VWF levels has been reported in inflammatory condition, similarly to the present study.…”

“…In cultured endothelial cells, VWF exocytosis from Weibel-Palade bodies is induced by multiple receptor agonists, including histamine, 8 thrombin, and vascular endothelial growth factor (VEGF). 9,10 On plasma release from endothelial cells, these ultralarge multimers are temporarily retained on the endothelium and cleaved by the plasmatic protease ADAMTS13 (a disintegrin and metalloprotease with thrombospondin domain 13) into smaller forms, released in plasma. 11 The physiologic VWF proteolytic activity of ADAMTS13 is increased by exposure to shear stress.…”

Shiga toxin (Stx)1B and Stx2B induce von Willebrand factor secretion from human umbilical vein endothelial cells through different signaling pathways

“…9 Alternatively, vascular endothelial growth factor (VEGF) stimulates VWF secretion through a pathway that depends on protein kinase C (PKC)-␦ but not on Ca 2ϩ or cAMP. 10 Whether any of these pathways contribute to Stx B-induced VWF secretion has not been determined previously.We have now shown that Stx1B and Stx2B activate distinct signaling pathways after binding to Gb3 on the cell surface. Stx1B increases intracellular Ca 2ϩ and in this respect resembles histamine or thrombin.…”