ANGPTL4-αvβ3 interaction counteracts hypoxia-induced vascular permeability by modulating Src signalling downstream of vascular endothelial growth factor receptor 2

Abstract

Dynamic control of endothelial cell junctions is essential for vascular homeostasis and angiogenesis. We recently provided genetic evidence that ANGPTL4 is a key regulator of vascular integrity both during developmental and in hypoxia-induced pathological conditions. The purpose of the present study was to decipher the molecular mechanisms through which ANGPTL4 regulates vascular integrity. Using surface plasmon resonance and proximity ligation assays, we show that ANGPTL4 binds integrin αvβ3. In vitro and in vivo functional assays with Angptl4-deficient mice demonstrate that ANGPTL4-αvβ3 interaction is necessary to mediate ANGPTL4 vasoprotective effects. Mechanistically, ANGPTL4-αvβ3 interaction enhances Src recruitment to integrin αvβ3 and inhibits Src signalling downstream of vascular endothelial growth factor receptor 2 (VEFGR2), thereby repressing hypoxia-induced breakdown of VEGFR2-VE-cadherin and VEGFR2-αvβ3 complexes. We further demonstrate that intravitreal injection of recombinant human ANGPTL4 limits vascular permeability and leads to increased adherens junction and tight junction integrity. These findings identify a novel mechanism by which ANGPTL4 counteracts hypoxia-driven vascular permeability through integrin αvβ3 binding, modulation of VEGFR2-Src kinase signalling, and endothelial junction stabilization. We further demonstrate that Angptl4-deficient mice show increased vascular leakage in vivo in a model of laser-induced choroidal neovascularization, indicating that this newly identified ANGPTL4-αvβ3 axis might be a target for pharmaceutical intervention in pathological conditions. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Antiinflammatory activity of ANGPTL4 facilitates macrophage polarization to induce cardiac repair

“…Then, we pretreated macrophages with cytochalasin D, which is known to inhibit exosome uptake, before coculture with hMSCs, and found no difference in CXCL10 inhibition in macrophages regardless of cytochalasin D pretreatment ( Figure 3B). Second, because ANGPTL4 has been reported to bind integrin β 1 or integrin α v β 3 (5,11), we neutralized these binding sites on macrophages by antibodies before coculture. Blockade of integrin β 1 and integrin α v β 3 impaired the inhibition of CXCL10 in THP-1 macrophages by hMSCs ( Figure 3C).…”

Angiopoietin-like 3 Is a Potential Biomarker for Retinopathy in Type 2 Diabetic Patients

“…Figure 2 shows the Àlog10(P) probability plot of the multivariable-adjusted association of various markers with DR stages in the cross-sectional study. Although both ANGPTL3 and ANGPTL4 bind to integrin a v b 3 to regulate angiogenesis, ANGPTL4 preserved the endothelial junction, 9 whereas ANGPTL3 improved endothelial cell adhesion and migration. 10 To further investigate the relationship of these proteins with DR, we compared the reported proteins that interact with ANGPTL3 and/or ANGPTL4 by network STRING analysis (from protein-protein interaction networks of STRING, version 10.5; https://string-db.…”

Angiopoietin‐like 4 production upon treatment with hypoxia and L‐mimosine in periodontal fibroblasts

“…6 It is expressed in a variety of tissues including adipose tissue, liver, pancreas, kidney, intestine, brain, placenta, skin, and blood. 7 Expression was also confirmed in oral tissues, for example, the mandible in the early phase of regeneration. 8 In vitro studies showed an increase of angiopoietin-like 4 in mineralizing periodontal cells at day 14 of culture.…”

“…Angiopoietin‐like 4 is involved in the regulation of the processes underlying lipid and glucose metabolism and regeneration . It is expressed in a variety of tissues including adipose tissue, liver, pancreas, kidney, intestine, brain, placenta, skin, and blood . Expression was also confirmed in oral tissues, for example, the mandible in the early phase of regeneration .…”