Abstract 513: Endothelial Barrier Function is Maintained by the RNA-Binding Protein Quaking

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Ruben G de Bruin ◽  
Martijn J Dane ◽  
DaeHyun Lee ◽  
Eric P van der Veer ◽  
Marko K Roeten ◽  
...  
Keyword(s):  
Binding Site ◽  
Barrier Function ◽  
Rna Binding ◽  
Adherens Junctions ◽  
Rna Binding Protein ◽  
Endothelial Barrier ◽  
Endothelial Monolayer ◽  
Endothelial Barrier Function ◽  
Vascular Integrity

Endothelial barrier function plays a major role in the onset of atherosclerosis. This barrier is maintained largely by adherens junctions. Remarkably, little is known about their regulation at the post–transcriptional level. We found that the RNA-binding protein Quaking (QKI), known for its function in embryonic blood vessel formation, is highly expressed in quiescent endothelial cells (EC) in vivo. In vitro, EC displayed increased levels of QKI when cultured under laminar, atheroprotective flow. Using KLF2 overexpression and a human QKI promoter reporter gene, we found that KLF2 mediates this increase in QKI expression. Subsequently, we aimed to investigate the role of QKI in EC vascular integrity. Interestingly, the mRNA of VE-cadherin, the prime adhesion protein in EC adherens junctions, contains a conserved QKI-binding site. We identified that the targeted reduction of QKI results in a reduction of VE-cadherin expression and organization at the cell periphery. These studies revealed a direct role for QKI in regulating VE-cadherin mRNA biology, as RNA-immunoprecipitation and luciferase-reporter assays revealed that QKI can directly bind to the VE-cadherin mRNA and induce transcript translation (4 fold ± 0.4; p<0.01), respectively. This effect was perturbed when the QKI-binding site was mutated. These results suggest that QKI acts to enhance barrier function. Overexpression of QKI markedly increased the capacity to form a high resistance endothelial monolayer (1.3 fold ± 0.96), while silencing of QKI markedly impaired EC barrier function (0.65 fold ± 0.13; p<0.05). To validate in vivo, we measured Bradykinin-induced vascular leakage in QKI viable mice (QKIv), which express decreased levels of the QKI protein. Indeed, QKIv mice displayed a 20% (p<0.05) increase in extravascular accumulation of Evans blue-labeled albumin compared to WT littermates. In conclusion, we show that QKI functions as a critical regulator of VE-cadherin, and the modulation of QKI expression affects endothelial monolayer integrity. These studies provide novel insight into the importance of post-transcriptional regulation on endothelial barrier function, and may have wide ranging implications for the preservation of vascular integrity in disease.

Abstract 296: The RNA-Binding Protein Quaking Maintains Endothelial Barrier Function Through Targeting Vascular Endothelial Cadherin mRNA

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Janine M van Gils ◽  
Ruben G de Bruin ◽  
Iris Schmidt ◽  
Eric P van der Veer ◽  
Marko K Roeten ◽  
...  
Keyword(s):  
High Resistance ◽  
Barrier Function ◽  
Rna Binding ◽  
Adherens Junctions ◽  
Rna Binding Protein ◽  
Endothelial Barrier ◽  
Vascular Endothelial ◽  
Endothelial Monolayer ◽  
Endothelial Barrier Function ◽  
Vascular Endothelial Cadherin

Endothelial cells (ECs) form a vital barrier between the blood and the artery wall, and play a major role in the onset of atherosclerosis. Endothelial monolayer integrity is determined largely by EC-cell interactions, where vascular endothelial cadherin (VE-cadherin) is the central adhesive component at these endothelial adherens junctions. While many of the receptors and signaling proteins involved in regulating these adherens junctions have been identified, surprisingly little is known regarding their regulation at the post[[Unable to Display Character: &#8208;]]transcriptional level. The RNA-binding protein Qauking (QKI), originally known for its function in the nervous system, has been demonstrated to be essential for blood vessel formation. We find that QKI is highly expressed in quiescent ECs, in vitro and in vivo. In contrast, human umbilical vein ECs displayed reduced levels of QKI in response to the inflammatory stimuli TNF-α as well as in cells lacking cell-cell contacts, suggesting that QKI may act to enhance barrier function. To test this, we specifically abrogated QKI expression in ECs and measured their capacity to form a high-resistance monolayer with Electrical Cell-substrate Impedance Sensing. Silencing of QKI did not affect EC adhesion or spreading, but markedly affected the capacity to form a high resistance endothelial monolayer. Consistent with these data, and the fact that VE-cadherin mRNA contains a putative QKI-response element, the targeted reduction in QKI was accompanied by a significant reduction in VE-cadherin expression at cell junctions. Importantly, we identified a direct role for QKI in regulating VE-cadherin mRNA biology, as RNA immunoprecipitation and luciferase-reporter assays revealed that QKI can directly bind to the VE-cadherin mRNA and regulate transcript stability, respectively. In conclusion, we show that the modulation of QKI expression levels affects endothelial monolayer integrity by functioning as a critical regulator of the VE-cadherin mRNA. These studies provide novel insight into a role for post-transcriptional regulation in the maintenance of endothelial barrier function, and may have wide ranging implications for the preservation of vascular integrity in disease.

Effect of p18 on Endothelial Barrier Function by Mediating Vascular Endothelial Rab11a-VE-cadherin Recycling

2021 ◽  
Author(s):  
Bo-Wen Xu ◽  
Zhi-Qiang Cheng ◽  
Xu-Ting Zhi ◽  
Xiao-Mei Yang ◽  
Zhi-Bo Yan
Keyword(s):  
Barrier Function ◽  
Adherens Junctions ◽  
Cecal Ligation ◽  
Underlying Mechanism ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Barrier Dysfunction ◽  
Recycling Endosome

Abstract Endothelial barrier integrity requires recycling of VE-cadherin to adherens junctions. Both p18 and Rab11a play significant roles in VE-cadherin recycling. However, the underlying mechanism and the role of p18 in activating Rab11a have yet to be elucidated. Performing in vitro and in vivo experiments, we showed that p18 protein bound to VE-cadherin before Rab11a through its VE-cadherin-binding domain (aa 1–39). Transendothelial resistance showed that overexpression of p18 promoted the circulation of VE-cadherin to adherens junctions and the recovery of the endothelial barrier. Silencing of p18 caused endothelial barrier dysfunction and prevented Rab11a-positive recycling endosome accumulation in the perinuclear recycling compartments. Furthermore, p18 knockdown in pulmonary microvessels markedly increased vascular leakage in mice challenged with lipopolysaccharide and cecal ligation puncture. This study showed that p18 regulated the pulmonary endothelial barrier function in vitro and in vivo by regulating the binding of Rab11a to VE-cadherin and the activation of Rab11a.

scholarly journals The RNA-binding protein quaking maintains endothelial barrier function and affects VE-cadherin and β-catenin protein expression

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ruben G. de Bruin ◽  
Eric P. van der Veer ◽  
Jurriën Prins ◽  
Dae Hyun Lee ◽  
Martijn J. C. Dane ◽  
...  
Keyword(s):  
Protein Expression ◽  
Barrier Function ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function

scholarly journals Phospholipase D2 restores endothelial barrier function by promoting PTPN14-mediated VE-cadherin dephosphorylation

2020 ◽  
Vol 295 (22) ◽  
pp. 7669-7685 ◽  
Author(s):  
Panfeng Fu ◽  
Ramaswamy Ramchandran ◽  
Mark Shaaya ◽  
Longshuang Huang ◽  
David L. Ebenezer ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Protein Tyrosine Phosphatase ◽  
Barrier Function ◽  
Adherens Junctions ◽  
Tyrosine Phosphatase ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Protein Tyrosine ◽  
Adhesion Junctions

Increased permeability of vascular lung tissues is a hallmark of acute lung injury and is often caused by edemagenic insults resulting in inflammation. Vascular endothelial (VE)-cadherin undergoes internalization in response to inflammatory stimuli and is recycled at cell adhesion junctions during endothelial barrier re-establishment. Here, we hypothesized that phospholipase D (PLD)-generated phosphatidic acid (PA) signaling regulates VE-cadherin recycling and promotes endothelial barrier recovery by dephosphorylating VE-cadherin. Genetic deletion of PLD2 impaired recovery from protease-activated receptor-1–activating peptide (PAR-1–AP)-induced lung vascular permeability and potentiated inflammation in vivo. In human lung microvascular endothelial cells (HLMVECs), inhibition or deletion of PLD2, but not of PLD1, delayed endothelial barrier recovery after thrombin stimulation. Thrombin stimulation of HLMVECs increased co-localization of PLD2-generated PA and VE-cadherin at cell-cell adhesion junctions. Inhibition of PLD2 activity resulted in prolonged phosphorylation of Tyr-658 in VE-cadherin during the recovery phase 3 h post-thrombin challenge. Immunoprecipitation experiments revealed that after HLMVECs are thrombin stimulated, PLD2, VE-cadherin, and protein-tyrosine phosphatase nonreceptor type 14 (PTPN14), a PLD2-dependent protein-tyrosine phosphatase, strongly associate with each other. PTPN14 depletion delayed VE-cadherin dephosphorylation, reannealing of adherens junctions, and barrier function recovery. PLD2 inhibition attenuated PTPN14 activity and reversed PTPN14-dependent VE-cadherin dephosphorylation after thrombin stimulation. Our findings indicate that PLD2 promotes PTPN14-mediated dephosphorylation of VE-cadherin and that redistribution of VE-cadherin at adherens junctions is essential for recovery of endothelial barrier function after an edemagenic insult.

Abstract 73: Bone Morphogenetic Protein Activity Modulates Endothelial Barrier Function

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Thomas Helbing ◽  
Elena Ketterer ◽  
Bianca Engert ◽  
Jennifer Heinke ◽  
Sebastian Grundmann ◽  
...  
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Barrier Function ◽  
Endothelial Permeability ◽  
Bmp Signaling ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function

Introduction: Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome, are associated with high morbidity and mortality in patients. During the progression of ALI, the endothelial cell barrier of the pulmonary vasculature becomes compromised, leading to pulmonary edema, a characteristic feature of ALI. It is well-established that EC barrier dysfunction is initiated by cytoskeletal remodeling, which leads to disruption of cell-cell contacts and formation of paracellular gaps, allowing penetration of protein-rich fluid and inflammatory cells. Bone morphogenetic proteins (BMPs) are important players in endothelial dysfunction and inflammation but their effects on endothelial permeability in ALI have not been investigated until now. Methods and Results: As a first approach to assess the role of BMPs in acute lung injury we analysed BMP4 and BMPER expression in an infectious (LPS) and a non-infectious (bleomycin) mouse models of acute lung injury. In both models BMP4 and BMPER protein expression levels were reduced demonstrated by western blots, suggesting that BMPs are involved in progression ALI. To assess the role of BMPs on vascular leakage, a key feature of ALI, BMP activity in mice was inhibited by i.p. administration of LDN193189, a small molecule that blocks BMP signalling. After 3 days Evans blue dye (EVB) was administered i.v. and dye extravasation into the lungs was quantified as a marker for vascular leakage. Interestingly, LDN193189 significantly increased endothelial permeability compared to control lungs, indicating that BMP signaling is involved in maintenance of endothelial barrier function. To quantify effects of BMP inhibition on endothelial barrier function in vitro, HUVECs were seeded onto transwell filters and were exposed to LDN193189. After 3 days FITC-dextrane was added and passage into the lower chamber was quantified as a marker for endothelial barrier function. Thrombin served as a positive control. As expected from our in vivo experiments inhibition of BMP signaling by LDN193189 enhanced FITC-dextrane passage. To study specific effects of BMPs on endothelial barrier function, two protagonist of the BMP family, BMP2 and BMP4, or BMP modulator BMPER were tested in the transwell assay in vitro. Interestingly BMP4 and BMPER, but not BMP2, reduced FITC-dextrane passage demonstrating that BMP4 and BMPER improved endothelial barrier function. Vice versa, specific knock down of BMP4 or BMPER increased leakage in transwell assays. Im immuncytochemistry silencing of BMPER or BMP4 induced hyperpermeability as a consequence of a pro-inflammatory endothelial phenotype characterised by reduced cell-cell contacts and increased actin stress fiber formation. Additionally, the pro-inflammatory endothelial phenotype was confirmed by real-time revealing increased expression of adhesion molecules ICAM-1 or proinflammatory cytokines such as IL-6 and IL-8 in endothelial cells after BMPER or BMP4 knock down. Confirming these in vitro results BMPER +/- mice exhibit increased extravasation of EVB into the lungs, indicating that partial loss of BMPER impairs endothelial barrier function in vitro and in vivo. Conclusion: We identify BMPER and BMP4 as local regulators of vascular permeability. Both are protective for endothelial barrier function and may open new therapeutic avenues in the treatment of acute lung injury.

scholarly journals Modulation of Rac1 Activity by ADMA/DDAH Regulates Pulmonary Endothelial Barrier Function

2009 ◽  
Vol 20 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Beata Wojciak-Stothard ◽  
Belen Torondel ◽  
Lan Zhao ◽  
Thomas Renné ◽  
James M. Leiper
Keyword(s):  
Nitric Oxide ◽  
Actin Cytoskeleton ◽  
Barrier Function ◽  
Endothelial Permeability ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Nitric Oxide Synthase Inhibitor ◽  
Rac1 Activity

Endogenously produced nitric oxide synthase inhibitor, asymmetric methylarginine (ADMA) is associated with vascular dysfunction and endothelial leakage. We studied the role of ADMA, and the enzymes metabolizing it, dimethylarginine dimethylaminohydrolases (DDAH) in the regulation of endothelial barrier function in pulmonary macrovascular and microvascular cells in vitro and in lungs of genetically modified heterozygous DDAHI knockout mice in vivo. We show that ADMA increases pulmonary endothelial permeability in vitro and in in vivo and that this effect is mediated by nitric oxide (NO) acting via protein kinase G (PKG) and independent of reactive oxygen species formation. ADMA-induced remodeling of actin cytoskeleton and intercellular adherens junctions results from a decrease in PKG-mediated phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and a subsequent down-regulation of Rac1 activity. The effects of ADMA on endothelial permeability, Rac1 activation and VASP phosphorylation are prevented by overexpression of active DDAHI and DDAHII, whereas inactive DDAH mutants have no effect. These findings demonstrate for the first time that ADMA metabolism critically determines pulmonary endothelial barrier function by modulating Rac1-mediated remodeling of the actin cytoskeleton and intercellular junctions.

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