scholarly journals Role of IQGAP1 in endothelial barrier enhancement caused by OxPAPC

2016 ◽  
Vol 311 (4) ◽  
pp. L800-L809 ◽  
Author(s):  
Yufeng Tian ◽  
Xinyong Tian ◽  
Grzegorz Gawlak ◽  
Nicolene Sarich ◽  
David B. Sacks ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Endothelial Barrier ◽  
Cell Junction ◽  
Protective Effects ◽  
P120 Catenin

Oxidized 1-palmitoyl-2-arachidonoyl- sn-glycero-3-phosphatidylcholine (OxPAPC) attenuates agonist-induced endothelial cell (EC) permeability and increases pulmonary endothelial barrier function via enhancement of both the peripheral actin cytoskeleton and cell junctions mediated by Rac1 and Cdc42 GTPases. This study evaluated the role for the multifunctional Rac1/Cdc42 effector and regulator, IQ domain containing GTPase-activating protein (IQGAP1), as a molecular transducer of the OxPAPC-mediated EC barrier-enhancing signal. IQGAP1 knockdown in endothelial cells by gene-specific small-interfering RNA abolished OxPAPC-induced enlargement of VE-cadherin-positive adherens junctions, suppressed peripheral accumulation of actin polymerization regulators, namely cortactin, neural Wiskott-Aldrich syndrome protein (N-WASP), and actin-related protein 3, and attenuated remodeling of the peripheral actin cytoskeleton. Inhibition of OxPAPC-induced barrier enhancement by IQGAP1 knockdown was due to suppressed Rac1 and Cdc42 activation. Expression of an IQGAP1 truncated mutant showed that the GTPase regulatory domain of IQGAP1 was essential for the OxPAPC-induced membrane localization of cortactin, adherens junction proteins VE-cadherin and p120-catenin, as well as for EC permeability response. IQGAP1 knockdown attenuated the protective effect of OxPAPC against thrombin-induced cell contraction, cell junction disruption, and EC permeability. These results demonstrate for the first time the role of IQGAP1 as a critical transducer of OxPAPC-induced Rac1/Cdc42 signaling to the actin cytoskeleton and adherens junctions, which promotes cortical cytoskeletal remodeling and EC barrier-protective effects of oxidized phospholipids.

scholarly journals Regulation of Adherens Junction Dynamics by Phosphorylation Switches

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Cristina Bertocchi ◽  
Megha Vaman Rao ◽  
Ronen Zaidel-Bar
Keyword(s):  
Actin Cytoskeleton ◽  
Enzymatic Activity ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Adaptor Proteins ◽  
Cell Junction ◽  
Internal Forces ◽  
Adherens Junction Proteins ◽  
Junction Proteins

Adherens junctions connect the actin cytoskeleton of neighboring cells through transmembrane cadherin receptors and a network of adaptor proteins. The interactions between these adaptors and cadherin as well as the activity of actin regulators localized to adherens junctions are tightly controlled to facilitate cell junction assembly or disassembly in response to changes in external or internal forces and/or signaling. Phosphorylation of tyrosine, serine, or threonine residues acts as a switch on the majority of adherens junction proteins, turning “on” or “off” their interactions with other proteins and/or their enzymatic activity. Here, we provide an overview of the kinases and phosphatases regulating phosphorylation of adherens junction proteins and bring examples of phosphorylation events leading to the assembly or disassembly of adherens junctions, highlighting the important role of phosphorylation switches in regulating their dynamics.

Role of vasodilator-stimulated phosphoprotein in cGMP-mediated protection of human pulmonary artery endothelial barrier function

2008 ◽  
Vol 294 (4) ◽  
pp. L686-L697 ◽  
Author(s):  
Otgonchimeg Rentsendorj ◽  
Tamara Mirzapoiazova ◽  
Djanybek Adyshev ◽  
Laura E. Servinsky ◽  
Thomas Renné ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Pulmonary Artery ◽  
Actin Polymerization ◽  
Cell Junctions ◽  
Endothelial Barrier ◽  
Protective Effects ◽  
Barrier Dysfunction ◽  
Endothelial Barrier Dysfunction ◽  
Human Pulmonary Artery

Increased pulmonary endothelial cGMP was shown to prevent endothelial barrier dysfunction through activation of protein kinase G (PKGI). Vasodilator-stimulated phosphoprotein (VASP) has been hypothesized to mediate PKGI barrier protection because VASP is a cytoskeletal phosphorylation target of PKGI expressed in cell-cell junctions. Unphosphorylated VASP was proposed to increase paracellular permeability through actin polymerization and stress fiber bundling, a process inhibited by PKGI-mediated phosphorylation of Ser157 and Ser239. To test this hypothesis, we examined the role of VASP in the transient barrier dysfunction caused by H2O2 in human pulmonary artery endothelial cell (HPAEC) monolayers studied without and with PKGI expression introduced by adenoviral infection (Ad.PKG). In the absence of PKGI expression, H2O2 (100–250 μM) caused a transient increased permeability and pSer157-VASP formation that were both attenuated by protein kinase C inhibition. Potentiation of VASP Ser157 phosphorylation by either phosphatase 2B inhibition with cyclosporin or protein kinase A activation with forskolin prolonged, rather than inhibited, the increased permeability caused by H2O2. With Ad.PKG infection, inhibition of VASP expression with small interfering RNA exacerbated H2O2-induced barrier dysfunction but had no effect on cGMP-mediated barrier protection. In addition, expression of a Ser-double phosphomimetic mutant VASP failed to reproduce the protective effects of activated PKGI. Finally, expression of a Ser-double phosphorylation-resistant VASP failed to interfere with the ability of cGMP/PKGI to attenuate H2O2-induced disruption of VE-cadherin homotypic binding. Our results suggest that VASP phosphorylation does not explain the protective effect of cGMP/PKGI on H2O2-induced endothelial barrier dysfunction in HPAEC.

scholarly journals Branched actin networks push against each other at adherens junctions to maintain cell–cell adhesion

2018 ◽  
Vol 217 (5) ◽  
pp. 1827-1845 ◽  
Author(s):  
Nadia Efimova ◽  
Tatyana M. Svitkina
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Mechanical Load ◽  
Adherens Junctions ◽  
Cell Junctions ◽  
Pull System ◽  
Actin Networks ◽  
Pulling Forces ◽  
Intercellular Adhesions ◽  
Cell Cell

Adherens junctions (AJs) are mechanosensitive cadherin-based intercellular adhesions that interact with the actin cytoskeleton and carry most of the mechanical load at cell–cell junctions. Both Arp2/3 complex–dependent actin polymerization generating pushing force and nonmuscle myosin II (NMII)-dependent contraction producing pulling force are necessary for AJ morphogenesis. Which actin system directly interacts with AJs is unknown. Using platinum replica electron microscopy of endothelial cells, we show that vascular endothelial (VE)-cadherin colocalizes with Arp2/3 complex–positive actin networks at different AJ types and is positioned at the interface between two oppositely oriented branched networks from adjacent cells. In contrast, actin–NMII bundles are located more distally from the VE-cadherin–rich zone. After Arp2/3 complex inhibition, linear AJs split, leaving gaps between cells with detergent-insoluble VE-cadherin transiently associated with the gap edges. After NMII inhibition, VE-cadherin is lost from gap edges. We propose that the actin cytoskeleton at AJs acts as a dynamic push–pull system, wherein pushing forces maintain extracellular VE-cadherin transinteraction and pulling forces stabilize intracellular adhesion complexes.

scholarly journals Role of protein tyrosine phosphatase SHP2 in barrier function of pulmonary endothelium

2010 ◽  
Vol 298 (3) ◽  
pp. L361-L370 ◽  
Author(s):  
K. L. Grinnell ◽  
B. Casserly ◽  
E. O. Harrington
Keyword(s):  
Endothelial Cells ◽  
Tyrosine Phosphorylation ◽  
Barrier Function ◽  
Adherens Junction ◽  
Fiber Formation ◽  
Cell Junctions ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Protein Tyrosine

Pulmonary edema is mediated in part by disruption of interendothelial cell contacts. Protein tyrosine phosphatases (PTP) have been shown to affect both cell-extracellular matrix and cell-cell junctions. The SH2 domain-containing nonreceptor PTP, SHP2, is involved in intercellular signaling through direct interaction with adherens junction proteins. In this study, we examined the role of SHP2 in pulmonary endothelial barrier function. Inhibition of SHP2 promoted edema formation in rat lungs and increased monolayer permeability in cultured lung endothelial cells. In addition, pulmonary endothelial cells demonstrated a decreased level of p190RhoGAP activity following inhibition of SHP2, events that were accompanied by a concomitant increase in RhoA activity. Furthermore, immunofluorescence microscopy confirmed enhanced actin stress fiber formation and diminished interendothelial staining of adherens junction complex-associated proteins upon SHP2 inhibition. Finally, immunoprecipitation and immunoblot analyses demonstrated increased tyrosine phosphorylation of VE-cadherin, β-catenin, and p190RhoGAP proteins, as well as decreased association between p120-catenin and VE-cadherin proteins. Our findings suggest that SHP2 supports basal pulmonary endothelial barrier function by coordinating the tyrosine phosphorylation profile of VE-cadherin, β-catenin, and p190RhoGAP and the activity of RhoA, signaling molecules important in adherens junction complex integrity.

scholarly journals Golgi-associated cPLA2α Regulates Endothelial Cell–Cell Junction Integrity by Controlling the Trafficking of Transmembrane Junction Proteins

2009 ◽  
Vol 20 (19) ◽  
pp. 4225-4234 ◽  
Author(s):  
Elsa Regan-Klapisz ◽  
Vincent Krouwer ◽  
Miriam Langelaar-Makkinje ◽  
Laxman Nallan ◽  
Michael Gelb ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Intracellular Trafficking ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Cell Junction ◽  
Tight Junction Formation ◽  
Junction Formation ◽  
Junction Proteins ◽  
Cell Cell

In endothelial cells specifically, cPLA2α translocates from the cytoplasm to the Golgi complex in response to cell confluence. Considering the link between confluence and cell–cell junction formation, and the emerging role of cPLA2α in intracellular trafficking, we tested whether Golgi-associated cPLA2α is involved in the trafficking of junction proteins. Here, we show that the redistribution of cPLA2α from the cytoplasm to the Golgi correlates with adherens junction maturation and occurs before tight junction formation. Disruption of adherens junctions using a blocking anti-VE-cadherin antibody reverses the association of cPLA2α with the Golgi. Silencing of cPLA2α and inhibition of cPLA2α enzymatic activity using various inhibitors result in the diminished presence of the transmembrane junction proteins VE-cadherin, occludin, and claudin-5 at cell–cell contacts, and in their accumulation at the Golgi. Altogether, our data support the idea that VE-cadherin triggers the relocation of cPLA2α to the Golgi and that in turn, Golgi-associated cPLA2α regulates the transport of transmembrane junction proteins through or from the Golgi, thereby controlling the integrity of endothelial cell–cell junctions.

scholarly journals The PI3K p110α isoform regulates endothelial adherens junctions via Pyk2 and Rac1

2010 ◽  
Vol 188 (6) ◽  
pp. 863-876 ◽  
Author(s):  
Robert J. Cain ◽  
Bart Vanhaesebroeck ◽  
Anne J. Ridley
Keyword(s):  
Barrier Function ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Endothelial Permeability ◽  
Cell Junctions ◽  
Endothelial Barrier ◽  
Regulatory Subunit ◽  
Nucleotide Exchange ◽  
Endothelial Barrier Function ◽  
Junction Protein

Endothelial cell–cell junctions control efflux of small molecules and leukocyte transendothelial migration (TEM) between blood and tissues. Inhibitors of phosphoinositide 3-kinases (PI3Ks) increase endothelial barrier function, but the roles of different PI3K isoforms have not been addressed. In this study, we determine the contribution of each of the four class I PI3K isoforms (p110α, -β, -γ, and -δ) to endothelial permeability and leukocyte TEM. We find that depletion of p110α but not other p110 isoforms decreases TNF-induced endothelial permeability, Tyr phosphorylation of the adherens junction protein vascular endothelial cadherin (VE-cadherin), and leukocyte TEM. p110α selectively mediates activation of the Tyr kinase Pyk2 and GTPase Rac1 to regulate barrier function. Additionally, p110α mediates the association of VE-cadherin with Pyk2, the Rac guanine nucleotide exchange factor Tiam-1 and the p85 regulatory subunit of PI3K. We propose that p110α regulates endothelial barrier function by inducing the formation of a VE-cadherin–associated protein complex that coordinates changes to adherens junctions with the actin cytoskeleton.

scholarly journals Tsc1 regulates tight junction independent of mTORC1

2021 ◽  
Vol 118 (30) ◽  
pp. e2020891118
Author(s):  
Mingqiang Lai ◽  
Wenchong Zou ◽  
Zelong Han ◽  
Ling Zhou ◽  
Zeyou Qiu ◽  
...  
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Tight Junction ◽  
Actin Cytoskeleton ◽  
Critical Role ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Whole Body ◽  
Mechanistic Target Of Rapamycin

Tuberous sclerosis complex 1 (Tsc1) is a tumor suppressor that functions together with Tsc2 to negatively regulate the mechanistic target of rapamycin complex 1 (mTORC1) activity. Here, we show that Tsc1 has a critical role in the tight junction (TJ) formation of epithelium, independent of its role in Tsc2 and mTORC1 regulation. When an epithelial cell establishes contact with neighboring cells, Tsc1, but not Tsc2, migrates from the cytoplasm to junctional membranes, in which it binds myosin 6 to anchor the perijunctional actin cytoskeleton to β-catenin and ZO-1. In its absence, perijunctional actin cytoskeleton fails to form. In mice, intestine-specific or inducible, whole-body Tsc1 ablation disrupts adherens junction/TJ structures in intestine or skin epithelia, respectively, causing Crohn’s disease–like symptoms in the intestine or psoriasis-like phenotypes on the skin. In patients with Crohn’s disease or psoriasis, junctional Tsc1 levels in epithelial tissues are markedly reduced, concomitant with the TJ structure impairment, suggesting that Tsc1 deficiency may underlie TJ-related diseases. These findings establish an essential role of Tsc1 in the formation of cell junctions and underpin its association with TJ-related human diseases.

scholarly journals Phosphorylation of Rab11-FIP2 regulates polarity in MDCK cells

2012 ◽  
Vol 23 (12) ◽  
pp. 2302-2318 ◽  
Author(s):  
Lynne A. Lapierre ◽  
Kenya M. Avant ◽  
Cathy M. Caldwell ◽  
Asli Oztan ◽  
Gerard Apodaca ◽  
...  
Keyword(s):  
Tight Junctions ◽  
Mdck Cell ◽  
Mdck Cells ◽  
Adherens Junction ◽  
Cellular Polarity ◽  
Interacting Protein ◽  
P120 Catenin ◽  
Myosin Vb ◽  
Darby Canine Kidney

The Rab11 effector Rab11-family interacting protein 2 (Rab11-FIP2) regulates transcytosis through its interactions with Rab11a and myosin Vb. Previous studies implicated Rab11-FIP2 in the establishment of polarity in Madin–Darby canine kidney (MDCK) cells through phosphorylation of Ser-227 by MARK2. Here we examine the dynamic role of Rab11-FIP2 phosphorylation on MDCK cell polarity. Endogenous Rab11-FIP2 phosphorylated on Ser-227 coalesces on vesicular plaques during the reestablishment of polarity after either monolayer wounding or calcium switch. Whereas expression of the nonphosphorylatable Rab11-FIP2(S227A) elicits a loss in lumen formation in MDCK cell cysts grown in Matrigel, the putative pseudophosphorylated Rab11-FIP2(S227E) mutant induces the formation of cysts with multiple lumens. On permeable filters, Rab11-FIP2(S227E)–expressing cells exhibit alterations in the composition of both the adherens and tight junctions. At the adherens junction, p120 catenin and K-cadherin are retained, whereas the majority of the E-cadherin is lost. Although ZO-1 is retained at the tight junction, occludin is lost and the claudin composition is altered. Of interest, the effects of Rab11-FIP2 on cellular polarity did not involve myosin Vb or Rab11a. These results indicate that Ser-227 phosphorylation of Rab11-FIP2 regulates the composition of both adherens and tight junctions and is intimately involved in the regulation of polarity in epithelial cells.

scholarly journals The G protein βγ subunit mediates reannealing of adherens junctions to reverse endothelial permeability increase by thrombin

2009 ◽  
Vol 206 (12) ◽  
pp. 2761-2777 ◽  
Author(s):  
Nebojsa Knezevic ◽  
Mohammad Tauseef ◽  
Tracy Thennes ◽  
Dolly Mehta
Keyword(s):  
Vascular Permeability ◽  
Focal Adhesion ◽  
Inflammatory Mediator ◽  
Adherens Junctions ◽  
Endothelial Permeability ◽  
Endothelial Barrier ◽  
Dependent Manner ◽  
Permeability Increase ◽  
Lung Vascular Permeability

The inflammatory mediator thrombin proteolytically activates protease-activated receptor (PAR1) eliciting a transient, but reversible increase in vascular permeability. PAR1-induced dissociation of Gα subunit from heterotrimeric Gq and G12/G13 proteins is known to signal the increase in endothelial permeability. However, the role of released Gβγ is unknown. We now show that impairment of Gβγ function does not affect the permeability increase induced by PAR1, but prevents reannealing of adherens junctions (AJ), thereby persistently elevating endothelial permeability. We observed that in the naive endothelium Gβ1, the predominant Gβ isoform is sequestered by receptor for activated C kinase 1 (RACK1). Thrombin induced dissociation of Gβ1 from RACK1, resulting in Gβ1 interaction with Fyn and focal adhesion kinase (FAK) required for FAK activation. RACK1 depletion triggered Gβ1 activation of FAK and endothelial barrier recovery, whereas Fyn knockdown interrupted with Gβ1-induced barrier recovery indicating RACK1 negatively regulates Gβ1-Fyn signaling. Activated FAK associated with AJ and stimulated AJ reassembly in a Fyn-dependent manner. Fyn deletion prevented FAK activation and augmented lung vascular permeability increase induced by PAR1 agonist. Rescuing FAK activation in fyn−/− mice attenuated the rise in lung vascular permeability. Our results demonstrate that Gβ1-mediated Fyn activation integrates FAK with AJ, preventing persistent endothelial barrier leakiness.

scholarly journals Increased Expression of Adherens Junction Components in Mouse Liver following Bile Duct Ligation

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 636 ◽  
Author(s):  
Van Campenhout ◽  
Crespo Yanguas ◽  
Cooreman ◽  
Gijbels ◽  
Leroy ◽  
...  
Keyword(s):  
Bile Duct ◽  
Mouse Liver ◽  
Bile Duct Ligation ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Tissue Architecture ◽  
Fibrotic Liver ◽  
Protein Levels ◽  
Duct Ligation

Adherens junctions, consisting of cadherins and catenins, are a group of cell-to-cell junctions that mediate mechanistic linkage between neighboring cells. By doing so, adherens junctions ensure direct intercellular contact and play an indispensable role in maintaining tissue architecture. Considering these critical functions, it is not surprising that adherens junctions are frequently involved in disease. In the present study, the effects of bile duct ligation—a surgical procedure to experimentally induce cholestatic and fibrotic liver pathology—on hepatic adherens junctions were investigated in mice. In essence, it was found that liver mRNA and protein levels of E-cadherin, β-catenin and γ-catenin drastically increase following bile duct ligation. These results could suggest a cytoprotective role for hepatic adherens junctions following bile duct ligation.

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