Plasminogen Activator Inhibitor-1 Inhibits Angiogenic Signaling by Uncoupling Vascular Endothelial Growth Factor Receptor-2-α _V β ₃ Integrin Cross Talk

Abstract

Objective Plasminogen activator inhibitor-1 (PAI-1) regulates angiogenesis via effects on extracellular matrix proteolysis and cell adhesion. However, no previous study has implicated PAI-1 in controlling vascular endothelial growth factor (VEGF) signaling. We tested the hypothesis that PAI-1 down-regulates VEGF receptor-2 (VEGFR-2) activation by inhibiting a vitronectin (VN)-dependent cooperative binding interaction between VEGFR-2 and αVβ3. Approach and Results We studied PAI-1's effects on VEGF signaling in human umbilical vein endothelial cells (HUVECs). PAI-1 inhibited VEGF-induced phosphorylation of VEGFR-2 in HUVECs grown on VN, but not on fibronectin or collagen. PAI-1 inhibited binding of VEGFR-2 to β3 integrin, VEGFR-2 endocytosis, and intracellular signaling pathways downstream of VEGFR-2. The anti-VEGF effect of PAI-1 was mediated by 2 distinct pathways, one requiring binding to VN and another requiring binding to very-low-density-lipoprotein receptor (VLDLR). PAI-1 inhibited VEGF-induced angiogenesis in vitro and in vivo, and pharmacological inhibition of PAI-1 promoted collateral arteriole development and recovery of hindlimb perfusion after femoral artery interruption. Conclusions PAI-1 inhibits activation of VEGFR-2 by VEGF by disrupting a VN-dependent, pro-angiogenic binding interaction involving αVβ3 and VEGFR-2. These results broaden our understanding of the roles of PAI-1, VN, and endocytic receptors in regulating VEGFR-2 activation and suggest novel therapeutic strategies for regulating VEGF signaling.

Key Proteins Involved in Spheroid Formation and Angiogenesis in Endothelial Cells After Long-Term Exposure to Simulated Microgravity

“…IL-8 can up-regulate IL6 and VEGFA expression, while IL-6 exerts influence on VEGFA, VCAM-1, ICAM-1, TIMP-1 and CCL2 expression [37-39]. VEGFA is also regulated by BDNF, LCN2 and PAI-1, but has positive regulatory effects on FN1 [40, 41]. …”

“…In addition, the inhibitory effect on VEGFA may be attenuated (see Fig. 7 red line, [40]). In clinical settings, increased plasma levels of plasmin are associated with an increased risk of atherosclerosis and myocardial infarction[63].…”

Hydroxysafflor Yellow A Promotes Angiogenesis via the Angiopoietin 1/ Tie-2 Signaling Pathway

“…The formation of tubes by HUVEC (1 × 10 5 /well) was studied as described [29] using 24-well plates coated with growth-factor-reduced Matrigel. Suspended cells were added to each coated well and maintained in 1% FBS growth medium containing HSYA (0, 1, 10, and 50 μ M ).…”

“…Unilateral hindlimb ischemia was induced in mice by ligation and excision of a segment of the left femoral artery, as previously described [29,30]. After recovering from surgery, the mice were treated with HSYA (6 mg/kg body weight dissolved in 1 mL saline) or the vehicle control administered for 11 days after surgery once daily via the tail vein.…”

4G/4G PAI-1 gene variant in a patient with non-healing ulcers

“…[2,3,7,8] PAI-1 has also been shown to delay wound healing in vitro mostly through impairing angiogenesis and by inhibiting integrinvitronectin and vitronectin-vitronectin which are essential for cell migration and angiogenesis though activation of vascular endothelial growth factor receptor 2. [9][10][11] Our patient presents with multiple, chronic, non-healing wounds of varying locations and depths. An extensive work up was only significant for the homozygous 4G/4G mutation in the promoter sequence of PAI-1, resulting in increased PAI-1 levels.…”