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Wu Z, Liu Q, Zhao Y, Fang C, Zheng W, Zhao Z, Zhang N, Yang X. Rhogef17: A novel target for endothelial barrier function. Biomed Pharmacother 2024; 170:115983. [PMID: 38134633 DOI: 10.1016/j.biopha.2023.115983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/29/2023] [Accepted: 12/02/2023] [Indexed: 12/24/2023] Open
Abstract
ARHGEF17 encodes the protein RhoGEF17, which is highly expressed in vascular endothelial cells. It is a guanine nucleotide exchange factor (GEF) that accelerates the exchange of GDP with GTP on many small GTPases through its Dbl homology (DH) domain, enabling the activation of Rho-GTPases such as RhoA, RhoB, and RhoC. Rho GTPase-regulated changes in the actin cytoskeleton and cell adhesion kinetics are the main mechanisms mediating many endothelial cell (EC) alterations, including cell morphology, migration, and division changes, which profoundly affect EC barrier function. This review focuses on ARHGEF17 expression, activation and biological functions in ECs, linking its regulation of cellular morphology, migration, mitosis and other cellular behaviors to disease onset and progression. Understanding ARHGEF17 mechanisms of action will contribute to the design of therapeutic approaches targeting RhoGEF17, a potential drug target for the treatment of various endothelium-related diseases, Such as vascular inflammation, carcinogenesis and transendothelial metastasis of tumors.
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Affiliation(s)
- Zhuolin Wu
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China; Tianjin Neurological Institute, Key Laboratory of Post-Neuroinjury Neuro-Repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin Medical University General Hospital, Tianjin, China
| | - Quanlei Liu
- Department of Neurosurgery, Capital Medical University, Xuanwu Hospital, Beijing, China
| | - Yan Zhao
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China; Tianjin Neurological Institute, Key Laboratory of Post-Neuroinjury Neuro-Repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin Medical University General Hospital, Tianjin, China
| | | | - Wen Zheng
- Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Zilin Zhao
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China; Tianjin Neurological Institute, Key Laboratory of Post-Neuroinjury Neuro-Repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin Medical University General Hospital, Tianjin, China
| | - Nai Zhang
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China
| | - Xinyu Yang
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China; Tianjin Neurological Institute, Key Laboratory of Post-Neuroinjury Neuro-Repair and Regeneration in Central Nervous System, Ministry of Education and Tianjin City, Tianjin Medical University General Hospital, Tianjin, China.
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Calcium-dependent cAMP mediates the mechanoresponsive behaviour of endothelial cells to high-frequency nanomechanostimulation. Biomaterials 2023; 292:121866. [PMID: 36526351 DOI: 10.1016/j.biomaterials.2022.121866] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/10/2022] [Accepted: 10/18/2022] [Indexed: 12/15/2022]
Abstract
The endothelial junction plays a central role in regulating intravascular and interstitial tissue permeability. The ability to manipulate its integrity therefore not only facilitates an improved understanding of its underlying molecular mechanisms but also provides insight into potential therapeutic solutions. Herein, we explore the effects of short-duration nanometer-amplitude MHz-order mechanostimulation on interendothelial junction stability and hence the barrier capacity of endothelial monolayers. Following an initial transient in which the endothelial barrier is permeabilised due to Rho-ROCK-activated actin stress fibre formation and junction disruption typical of a cell's response to insults, we observe, quite uniquely, the integrity of the endothelial barrier to not only spontaneously recover but also to be enhanced considerably-without the need for additional stimuli or intervention. Central to this peculiar biphasic response, which has not been observed with other stimuli to date, is the role of second messenger calcium and cyclic adenosine monophosphate (cAMP) signalling. We show that intracellular Ca2+, modulated by the high frequency excitation, is responsible for activating reorganisation of the actin cytoskeleton in the barrier recovery phase, in which circumferential actin bundles are formed to stabilise the adherens junctions via a cAMP-mediated Epac1-Rap1 pathway. Despite the short-duration stimulation (8 min), the approximate 4-fold enhancement in the transendothelial electrical resistance (TEER) of endothelial cells from different tissue sources, and the corresponding reduction in paracellular permeability, was found to persist over hours. The effect can further be extended through multiple treatments without resulting in hyperpermeabilisation of the barrier, as found with prolonged use of chemical stimuli, through which only 1.1- to 1.2-fold improvement in TEER has been reported. Such an ability to regulate and enhance endothelial barrier capacity is particularly useful in the development of in vitro barrier models that more closely resemble their in vivo counterparts.
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Jin Y, Ding Y, Richards M, Kaakinen M, Giese W, Baumann E, Szymborska A, Rosa A, Nordling S, Schimmel L, Akmeriç EB, Pena A, Nwadozi E, Jamalpour M, Holstein K, Sáinz-Jaspeado M, Bernabeu MO, Welsh M, Gordon E, Franco CA, Vestweber D, Eklund L, Gerhardt H, Claesson-Welsh L. Tyrosine-protein kinase Yes controls endothelial junctional plasticity and barrier integrity by regulating VE-cadherin phosphorylation and endocytosis. NATURE CARDIOVASCULAR RESEARCH 2022; 1:1156-1173. [PMID: 37936984 PMCID: PMC7615285 DOI: 10.1038/s44161-022-00172-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 10/25/2022] [Indexed: 11/09/2023]
Abstract
Vascular endothelial (VE)-cadherin in endothelial adherens junctions is an essential component of the vascular barrier, critical for tissue homeostasis and implicated in diseases such as cancer and retinopathies. Inhibitors of Src cytoplasmic tyrosine kinase have been applied to suppress VE-cadherin tyrosine phosphorylation and prevent excessive leakage, edema and high interstitial pressure. Here we show that the Src-related Yes tyrosine kinase, rather than Src, is localized at endothelial cell (EC) junctions where it becomes activated in a flow-dependent manner. EC-specific Yes1 deletion suppresses VE-cadherin phosphorylation and arrests VE-cadherin at EC junctions. This is accompanied by loss of EC collective migration and exaggerated agonist-induced macromolecular leakage. Overexpression of Yes1 causes ectopic VE-cadherin phosphorylation, while vascular leakage is unaffected. In contrast, in EC-specific Src-deficiency, VE-cadherin internalization is maintained, and leakage is suppressed. In conclusion, Yes-mediated phosphorylation regulates constitutive VE-cadherin turnover, thereby maintaining endothelial junction plasticity and vascular integrity.
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Affiliation(s)
- Yi Jin
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Yindi Ding
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Mark Richards
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Mika Kaakinen
- Oulu Centre for Cell-Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Wolfgang Giese
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Elisabeth Baumann
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Charité – Universitatsmedizin Berlin, Berlin, Germany
| | - Anna Szymborska
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - André Rosa
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Sofia Nordling
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Lilian Schimmel
- Institute for Molecular Bioscience, Division of Cell and Developmental Biology, The University of Queensland, Brisbane QLD, Australia
| | - Emir Bora Akmeriç
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Charité – Universitatsmedizin Berlin, Berlin, Germany
| | - Andreia Pena
- Instituto de Medicina Molecular - Joao lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - Emmanuel Nwadozi
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Maria Jamalpour
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Katrin Holstein
- Department of Vascular Cell Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Miguel Sáinz-Jaspeado
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
| | - Miguel O. Bernabeu
- Centre for Medical Informatics, Usher Institute, The University of Edinburgh, UK
- The Bayes Centre, The University of Edinburgh, UK
| | - Michael Welsh
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Emma Gordon
- Institute for Molecular Bioscience, Division of Cell and Developmental Biology, The University of Queensland, Brisbane QLD, Australia
| | - Claudio A. Franco
- Instituto de Medicina Molecular - Joao lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Portugal
- Universidade Católica Portuguesa, Católica Medical School, Católica Biomedical Research Centre, Portugal
| | - Dietmar Vestweber
- Department of Vascular Cell Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Lauri Eklund
- Oulu Centre for Cell-Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Holger Gerhardt
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
- Charité – Universitatsmedizin Berlin, Berlin, Germany
| | - Lena Claesson-Welsh
- Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck, Beijer and SciLifeLab Laboratory, Uppsala, Sweden
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Cytoskeleton Elements Contribute to Prion Peptide-Induced Endothelial Barrier Breakdown in a Blood–Brain Barrier In Vitro System. Int J Mol Sci 2022; 23:ijms232012126. [PMID: 36293002 PMCID: PMC9603506 DOI: 10.3390/ijms232012126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/02/2022] [Accepted: 10/07/2022] [Indexed: 11/17/2022] Open
Abstract
The mechanisms involved in the interaction of PrP 106-126, a peptide corresponding to the prion protein amyloidogenic region, with the blood–brain barrier (BBB) were studied. PrP 106-126 treatment that was previously shown to impair BBB function, reduced cAMP levels in cultured brain endothelial cells, increased nitric oxide (NO) levels, and changed the activation mode of the small GTPases Rac1 (inactivation) and RhoA (activation). The latter are well established regulators of endothelial barrier properties that act via cytoskeletal elements. Indeed, liquid chromatography-mass spectrometry (LC-MS)-based proteomic profiling study revealed extensive changes in expression of cytoskeleton-related proteins. These results shed light on the nature of the interaction between the prion peptide PrP 106-126 and the BBB and emphasize the importance of the cytoskeleton in endothelium response to prion- induced stress.
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Yue Q, Xu Y, Lin L, Hoi MPM. Canthin-6-one (CO) from Picrasma quassioides (D.Don) Benn. ameliorates lipopolysaccharide (LPS)-induced astrocyte activation and associated brain endothelial disruption. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2022; 101:154108. [PMID: 35472694 DOI: 10.1016/j.phymed.2022.154108] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/14/2022] [Accepted: 04/14/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Canthin-6-one (CO) is an active ingredient found in Picrasma quassioides (D.Don) Benn. (PQ) that displays various biological activities including anti-inflammatory properties. Several studies reported PQ displayed neuroprotective activities, but its effects on astrocytes have not yet been investigated. Astrocytes are crucial regulators of neuroinflammatory responses under pathological conditions in the central nervous system (CNS). Proinflammatory astrocytes can induce the blood-brain barrier (BBB) breakdown, which plays a key role in the progression of neurodegenerative disorder (ND). PURPOSE This study aims to investigate the anti-neuroinflammatory effects of CO in LPS-induced astrocyte activation and its underlying mechanisms in protecting the blood-brain barrier (BBB) in vitro. METHODS Mouse astrocytes (C8-D1A) were activated with lipopolysaccharide (LPS) with or without CO pretreatment. Effects of CO on astrocyte cell viability, secretions of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and nitric oxide (NO) were determined. Intracellular transcriptions and translations of proinflammatory mediators, molecular signaling, [Ca2+] and the levels of reactive oxygen species (ROS) were evaluated by RT-PCR, western blotting, and flow cytometry, respectively. Astrocyte-conditioned medium (ACM) was further prepared for incubating endothelial monolayer (bEnd.3) grown on transwell. Endothelial disruptions were evaluated by transendothelial electrical resistance (TEER), FITC-dextran permeability and monocyte adhesion assays. Endothelial tight junctions (TJs) and molecular signaling pathways were evaluated by immunofluorescence staining and western blotting. RESULTS CO attenuated LPS-induced expression of astrocytic proinflammatory mediators (TNF-α, IL-1β, IL-6, NO) and inhibited deleterious molecular activities including inducible nitric oxide synthase (iNOS), p-NFκB and p-STAT3 in astrocytes. Incubation of ACM collected from CO-treated astrocytes significantly ameliorated endothelial disruptions, reduced expressions of endothelial cytokine receptors (IL-6R, gp130 (IL-6RB), TNFR and IL-1R), suppressed proinflammatory pathways, MAPKs (p-AKT, p-MEK, p-ERK, p-p38, p-JNK) and p-STAT3, restored endothelial stabilizing pathways (p-Rac 1) and upregulated beneficial endothelial nitric oxide synthase (eNOS). CONCLUSION Our study demonstrates for the first time CO exhibited potent protective effects against astrocyte-mediated proinflammatory responses and associated endothelial barrier disruptions.
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Affiliation(s)
- Qian Yue
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, N22-7012, Avenida da Universidade, Taipa, Macau, SAR, China; DPS, Faculty of Health Sciences, University of Macau, Macau, SAR, China
| | - Yunshao Xu
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, N22-7012, Avenida da Universidade, Taipa, Macau, SAR, China; DPS, Faculty of Health Sciences, University of Macau, Macau, SAR, China
| | - Ligen Lin
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, N22-7012, Avenida da Universidade, Taipa, Macau, SAR, China; DPS, Faculty of Health Sciences, University of Macau, Macau, SAR, China
| | - Maggie Pui Man Hoi
- Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine, University of Macau, N22-7012, Avenida da Universidade, Taipa, Macau, SAR, China; DPS, Faculty of Health Sciences, University of Macau, Macau, SAR, China.
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Carlini F, Maroccia Z, Fiorentini C, Travaglione S, Fabbri A. Effects of the Escherichia coli Bacterial Toxin Cytotoxic Necrotizing Factor 1 on Different Human and Animal Cells: A Systematic Review. Int J Mol Sci 2021; 22:ijms222212610. [PMID: 34830494 PMCID: PMC8621085 DOI: 10.3390/ijms222212610] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 12/13/2022] Open
Abstract
Cytotoxic necrotizing factor 1 (CNF1) is a bacterial virulence factor, the target of which is represented by Rho GTPases, small proteins involved in a huge number of crucial cellular processes. CNF1, due to its ability to modulate the activity of Rho GTPases, represents a widely used tool to unravel the role played by these regulatory proteins in different biological processes. In this review, we summarized the data available in the scientific literature concerning the observed in vitro effects induced by CNF1. An article search was performed on electronic bibliographic resources. Screenings were performed of titles, abstracts, and full-texts according to PRISMA guidelines, whereas eligibility criteria were defined for in vitro studies. We identified a total of 299 records by electronic article search and included 76 original peer-reviewed scientific articles reporting morphological or biochemical modifications induced in vitro by soluble CNF1, either recombinant or from pathogenic Escherichia coli extracts highly purified with chromatographic methods. Most of the described CNF1-induced effects on cultured cells are ascribable to the modulating activity of the toxin on Rho GTPases and the consequent effects on actin cytoskeleton organization. All in all, the present review could be a prospectus about the CNF1-induced effects on cultured cells reported so far.
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Affiliation(s)
- Francesca Carlini
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.C.); (Z.M.); (S.T.)
| | - Zaira Maroccia
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.C.); (Z.M.); (S.T.)
| | - Carla Fiorentini
- Associazione Ricerca Terapie Oncologiche Integrate, ARTOI, 00165 Rome, Italy;
| | - Sara Travaglione
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.C.); (Z.M.); (S.T.)
| | - Alessia Fabbri
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161 Rome, Italy; (F.C.); (Z.M.); (S.T.)
- Correspondence: ; Tel.: +39-06-4990-2939
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Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research. Cells 2021; 10:cells10081844. [PMID: 34440613 PMCID: PMC8391638 DOI: 10.3390/cells10081844] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 01/19/2023] Open
Abstract
Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.
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Majolée J, Podieh F, Hordijk PL, Kovačević I. The interplay of Rac1 activity, ubiquitination and GDI binding and its consequences for endothelial cell spreading. PLoS One 2021; 16:e0254386. [PMID: 34252134 PMCID: PMC8274835 DOI: 10.1371/journal.pone.0254386] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 06/24/2021] [Indexed: 11/19/2022] Open
Abstract
Signaling by the Rho GTPase Rac1 is key to the regulation of cytoskeletal dynamics, cell spreading and adhesion. It is widely accepted that the inactive form of Rac1 is bound by Rho GDI, which prevents Rac1 activation and Rac1-effector interactions. In addition, GDI-bound Rac1 is protected from proteasomal degradation, in line with data showing that Rac1 ubiquitination occurs exclusively when Rac1 is activated. We set out to investigate how Rac1 activity, GDI binding and ubiquitination are linked. We introduced single amino acid mutations in Rac1 which differentially altered Rac1 activity, and compared whether the level of Rac1 activity relates to Rac1 ubiquitination and GDI binding. Results show that Rac1 ubiquitination and the active Rac1 morphology is proportionally increased with Rac1 activity. Similarly, we introduced lysine-to-arginine mutations in constitutively active Rac1 to inhibit site-specific ubiquitination and analyze this effect on Rac1 signaling output and ubiquitination. These data show that the K16R mutation inhibits GTP binding, and consequently Rac1 activation, signaling and-ubiquitination, while the K147R mutation does not block Rac1 signaling, but does inhibits its ubiquitination. In both sets of mutants, no direct correlation was observed between GDI binding and Rac1 activity or -ubiquitination. Taken together, our data show that a strong, positive correlation exists between Rac1 activity and its level of ubiquitination, but also that GDI dissociation does not predispose Rac1 to ubiquitination.
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Affiliation(s)
- Jisca Majolée
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Fabienne Podieh
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Peter L. Hordijk
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Igor Kovačević
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
- Department of Gene Regulation, Institute of Physiological Chemistry, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
- * E-mail:
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Effect of X-rays on transcript expression of rat brain microvascular endothelial cells: role of calcium signaling in X-ray-induced endothelium damage. Biosci Rep 2021; 40:222641. [PMID: 32285918 PMCID: PMC7189493 DOI: 10.1042/bsr20193760] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 03/19/2020] [Accepted: 04/03/2020] [Indexed: 12/13/2022] Open
Abstract
Radiation-induced brain edema is a serious adverse effect of radiotherapy. Although there are many causes of radiation-induced brain edema, the pathogenesis is not clear and clinical treatment is not ideal. Therefore, knowing the differential expression of the brain microvascular endothelial cell (BMEC) transcriptome after brain radiotherapy may shed light on the pathogenesis of radiation-induced brain edema. The present study used RNA-Seq technique to identify 383 BMEC transcripts differentially expressed (many 2-fold or higher; P < 0.05) between control and X-ray–treated primary cultured rat BMECs. Compared with controls, X-ray–treated BMECs had 183 significantly up-regulated transcripts and 200 significantly down-regulated transcripts. The differentially expressed genes were associated with the biological processes of the cell cycle, apoptosis, vascular permeability, and extracellular junctions. The functional changes identified in the X-ray–treated BMECs included Ca2+ signaling, phosphoinositide 3-kinase–Akt signaling, and methionine degradation. These results indicated that transcript expression was substantially affected by radiation exposure and the proteins encoded by these differentially expressed genes may play a significant role in radiotherapy-induced brain edema. Our findings provide additional insight into the molecular mechanisms of radiation-induced brain edema and may be helpful in the development of clinical treatment of this adverse reaction to radiotherapy.
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Claesson-Welsh L, Dejana E, McDonald DM. Permeability of the Endothelial Barrier: Identifying and Reconciling Controversies. Trends Mol Med 2020; 27:314-331. [PMID: 33309601 DOI: 10.1016/j.molmed.2020.11.006] [Citation(s) in RCA: 360] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/16/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022]
Abstract
Leakage from blood vessels into tissues is governed by mechanisms that control endothelial barrier function to maintain homeostasis. Dysregulated endothelial permeability contributes to many conditions and can influence disease morbidity and treatment. Diverse approaches used to study endothelial permeability have yielded a wealth of valuable insights. Yet, ongoing questions, technical challenges, and unresolved controversies relating to the mechanisms and relative contributions of barrier regulation, transendothelial sieving, and transport of fluid, solutes, and particulates complicate interpretations in the context of vascular physiology and pathophysiology. Here, we describe recent in vivo findings and other advances in understanding endothelial barrier function with the goal of identifying and reconciling controversies over cellular and molecular processes that regulate the vascular barrier in health and disease.
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Affiliation(s)
- Lena Claesson-Welsh
- Uppsala University, Rudbeck, SciLifeLab and Beijer Laboratories, Department of Immunology, Genetics and Pathology, Uppsala, Sweden.
| | - Elisabetta Dejana
- Uppsala University, Rudbeck, SciLifeLab and Beijer Laboratories, Department of Immunology, Genetics and Pathology, Uppsala, Sweden; IFOM-FIRC Institute of Molecular Oncology, Milan, Italy
| | - Donald M McDonald
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA; UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA; Department of Anatomy, University of California, San Francisco, San Francisco, CA, USA.
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Activation of SIRT1 ameliorates LPS-induced lung injury in mice via decreasing endothelial tight junction permeability. Acta Pharmacol Sin 2019; 40:630-641. [PMID: 30022154 DOI: 10.1038/s41401-018-0045-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 05/12/2018] [Indexed: 01/22/2023]
Abstract
The integrity of the endothelial barrier is a determinant of the prognosis of lipopolysaccharide (LPS)-induced acute lung injury (ALI). In this study, we investigated whether and how Sirtuin 1 (SIRT1) maintained the vascular integrity during ALI. An experimental model of ALI was established in mice through intratracheal administration of LPS (10 mg/kg). LPS stimulation significantly increased the pulmonary permeability and decreased the expression of SIRT1 and tight junction proteins (TJs), including occludin, claudin-5, tight junction protein 1 and tight junction protein 2. Morphological studies showed that LPS induced obvious lung injury with inflammatory cell infiltration in the interstitial and alveolar space, hemorrhage, edema, and the thickened alveolar wall compared to the control mice. Intratracheal administration of the selective SIRT1 activator SRT1720 (6.25 mg/kg) significantly attenuated LPS-induced lung injury, lung hyper-permeability and increased TJs expression, whereas intratracheal administration of the selective SIRT1 inhibitor EX527 (6.25 mg/kg) aggravated LPS-induced ALI. Similar protective effects of SIRT1 on pulmonary cellular permeability were observed in primary human pulmonary microvascular endothelial cells treated with LPS (2 mg/mL) in vitro. We further demonstrated that the RhoA/ROCK signaling pathway was activated in SIRT1 regulation of tight junction permeability. The RhoA/ROCK inhibitor Y-27632 (10 μM) increased the expression of TJs and reversed LPS- or EX527-induced hyper-permeability. In conclusion, SIRT1 ameliorates LPS-induced lung injury via decreasing endothelial tight junction permeability, possibly via RhoA/ROCK signaling pathway. This finding may contribute to the development of new therapeutic approaches for lung injury.
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Flentje A, Kalsi R, Monahan TS. Small GTPases and Their Role in Vascular Disease. Int J Mol Sci 2019; 20:ijms20040917. [PMID: 30791562 PMCID: PMC6413073 DOI: 10.3390/ijms20040917] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 01/31/2019] [Accepted: 02/07/2019] [Indexed: 12/18/2022] Open
Abstract
Over eighty million people in the United States have cardiovascular disease that can affect the heart causing myocardial infarction; the carotid arteries causing stroke; and the lower extremities leading to amputation. The treatment for end-stage cardiovascular disease is surgical—either endovascular therapy with balloons and stents—or open reconstruction to reestablish blood flow. All interventions damage or destroy the protective inner lining of the blood vessel—the endothelium. An intact endothelium is essential to provide a protective; antithrombotic lining of a blood vessel. Currently; there are no agents used in the clinical setting that promote reendothelialization. This process requires migration of endothelial cells to the denuded vessel; proliferation of endothelial cells on the denuded vessel surface; and the reconstitution of the tight adherence junctions responsible for the formation of an impermeable surface. These processes are all regulated in part and are dependent on small GTPases. As important as the small GTPases are for reendothelialization, dysregulation of these molecules can result in various vascular pathologies including aneurysm formation, atherosclerosis, diabetes, angiogenesis, and hypertension. A better understanding of the role of small GTPases in endothelial cell migration is essential to the development for novel agents to treat vascular disease.
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Affiliation(s)
- Alison Flentje
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
| | - Richa Kalsi
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
| | - Thomas S Monahan
- Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, 22 South Greene Street, Suite S10B00, Baltimore, MD 21201, USA.
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Endothelial Protrusions in Junctional Integrity and Barrier Function. CURRENT TOPICS IN MEMBRANES 2018; 82:93-140. [PMID: 30360784 DOI: 10.1016/bs.ctm.2018.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Endothelial cells of the microcirculation form a semi-permeable diffusion barrier between the blood and tissues. This permeability of the endothelium, particularly in the capillaries and postcapillary venules, is a normal physiological function needed for blood-tissue exchange in the microcirculation. During inflammation, microvascular permeability increases dramatically and can lead to tissue edema, which in turn can lead to dysfunction of tissues and organs. The molecular mechanisms that control the barrier function of endothelial cells have been under investigation for several decades and remain an important topic due to the potential for discovery of novel therapeutic strategies to reduce edema. This review highlights current knowledge of the cellular and molecular mechanisms that lead to endothelial hyperpermeability during inflammatory conditions associated with injury and disease. This includes a discussion of recent findings demonstrating temporal protrusions by endothelial cells that may contribute to intercellular junction integrity between endothelial cells and affect the diffusion distance for solutes via the paracellular pathway.
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14
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Histamine causes endothelial barrier disruption via Ca 2+-mediated RhoA activation and tension at adherens junctions. Sci Rep 2018; 8:13229. [PMID: 30185878 PMCID: PMC6125323 DOI: 10.1038/s41598-018-31408-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 08/03/2018] [Indexed: 12/21/2022] Open
Abstract
During inflammation, the disruption of the endothelial barrier leads to increased microvascular permeability. Whether tension along cell junctions contributes to histamine-induced endothelial barrier disruption remains unknown. Rapid Ca2+ influx induced by both histamine and thrombin was accompanied by endothelial barrier breakdown revealed as drop of transendothelial electric resistance in primary human microvascular endothelial cells. Interestingly, GLISA measurements revealed activation of RhoA but not inactivation of Rac1 at the time-point of barrier breakdown. FRET measurements showed activation of RhoA at intercellular junctions after both thrombin and histamine exposure. Breakdown coincided with increased stress fiber formation but not with translocation of vinculin, which was located along junctions in the resting state similar to postcapillary venules ex vivo. Moreover, increased tension at AJs was indicated by immunostaining with a conformation-sensitive antibody targeting the α18-subunit of α-catenin. Ca2+ chelation by BAPTA-AM and ROCK1 inhibition by Y27632 abolished both increase of tension along AJs as well as barrier dysfunction. Moreover, BAPTA-AM decreased RhoA activation following histamine stimulation, indicating a key role of Ca2+ signaling in barrier breakdown. Taken together, in response to histamine, Ca2+ via RhoA/ROCK activation along endothelial adherens junctions (AJs) appears to be critical for barrier disruption and presumably correlated with enhanced tension. However, vinculin appears not to be critical in this process.
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15
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Lee MC, Shei W, Chan AS, Chua BT, Goh SR, Chong YF, Hilmy MH, Nongpiur ME, Baskaran M, Khor CC, Aung T, Hunziker W, Vithana EN. Primary angle closure glaucoma (PACG) susceptibility gene PLEKHA7 encodes a novel Rac1/Cdc42 GAP that modulates cell migration and blood-aqueous barrier function. Hum Mol Genet 2018; 26:4011-4027. [PMID: 29016860 DOI: 10.1093/hmg/ddx292] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/18/2017] [Indexed: 12/21/2022] Open
Abstract
PLEKHA7, a gene recently associated with primary angle closure glaucoma (PACG), encodes an apical junctional protein expressed in components of the blood aqueous barrier (BAB). We found that PLEKHA7 is down-regulated in lens epithelial cells and in iris tissue of PACG patients. PLEKHA7 expression also correlated with the C risk allele of the sentinel SNP rs11024102 with the risk allele carrier groups having significantly reduced PLEKHA7 levels compared to non-risk allele carriers. Silencing of PLEKHA7 in human immortalized non-pigmented ciliary epithelium (h-iNPCE) and primary trabecular meshwork cells, which are intimately linked to BAB and aqueous humor outflow respectively, affected actin cytoskeleton organization. PLEKHA7 specifically interacts with GTP-bound Rac1 and Cdc42, but not RhoA, and the activation status of the two small GTPases is linked to PLEKHA7 expression levels. PLEKHA7 stimulates Rac1 and Cdc42 GTP hydrolysis, without affecting nucleotide exchange, identifying PLEKHA7 as a novel Rac1/Cdc42 GAP. Consistent with the regulatory role of Rac1 and Cdc42 in maintaining the tight junction permeability, silencing of PLEKHA7 compromises the paracellular barrier between h-iNPCE cells. Thus, downregulation of PLEKHA7 in PACG may affect BAB integrity and aqueous humor outflow via its Rac1/Cdc42 GAP activity, thereby contributing to disease etiology.
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Affiliation(s)
- Mei-Chin Lee
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - William Shei
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore
| | - Anita S Chan
- The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore.,Department of Glaucoma, Singapore National Eye Centre, Singapore 168751, Singapore
| | - Boon-Tin Chua
- Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Singapore 138673, Singapore
| | - Shuang-Ru Goh
- The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Yaan-Fun Chong
- The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Maryam H Hilmy
- Department of Pathology, Singapore General Hospital, Singapore 169856, Singapore
| | - Monisha E Nongpiur
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Mani Baskaran
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore.,Department of Glaucoma, Singapore National Eye Centre, Singapore 168751, Singapore
| | - Chiea-Chuen Khor
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,Department of Human Genetics, Genome Institute of Singapore, Agency for Science Technology and Research, Singapore 138672, Singapore.,Department of Biochemistry, National University of Singapore, Singapore 117596, Singapore
| | - Tin Aung
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore.,Department of Glaucoma, Singapore National Eye Centre, Singapore 168751, Singapore.,Department of Ophthalmology, National University of Singapore, Singapore 119228, Singapore
| | - Walter Hunziker
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Singapore 138673, Singapore.,Department of Physiology, National University of Singapore, Singapore 117593, Singapore
| | - Eranga N Vithana
- Ocular Genetics Research Group, Singapore Eye Research Institute, Singapore 169856, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore.,Department of Ophthalmology, National University of Singapore, Singapore 119228, Singapore
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16
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Radeva MY, Waschke J. Mind the gap: mechanisms regulating the endothelial barrier. Acta Physiol (Oxf) 2018; 222. [PMID: 28231640 DOI: 10.1111/apha.12860] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/21/2016] [Accepted: 02/16/2017] [Indexed: 12/11/2022]
Abstract
The endothelial barrier consists of intercellular contacts localized in the cleft between endothelial cells, which is covered by the glycocalyx in a sievelike manner. Both types of barrier-forming junctions, i.e. the adherens junction (AJ) serving mechanical anchorage and mechanotransduction and the tight junction (TJ) sealing the intercellular space to limit paracellular permeability, are tethered to the actin cytoskeleton. Under resting conditions, the endothelium thereby builds a selective layer controlling the exchange of fluid and solutes with the surrounding tissue. However, in the situation of an inflammatory response such as in anaphylaxis or sepsis intercellular contacts disintegrate in post-capillary venules leading to intercellular gap formation. The resulting oedema can cause shock and multi-organ failure. Therefore, maintenance as well as coordinated opening and closure of interendothelial junctions is tightly regulated. The two principle underlying mechanisms comprise spatiotemporal activity control of the small GTPases Rac1 and RhoA and the balance of the phosphorylation state of AJ proteins. In the resting state, junctional Rac1 and RhoA activity is enhanced by junctional components, actin-binding proteins, cAMP signalling and extracellular cues such as sphingosine-1-phosphate (S1P) and angiopoietin-1 (Ang-1). In addition, phosphorylation of AJ components is prevented by junction-associated phosphatases including vascular endothelial protein tyrosine phosphatase (VE-PTP). In contrast, inflammatory mediators inhibiting cAMP/Rac1 signalling cause strong activation of RhoA and induce AJ phosphorylation finally leading to endocytosis and cleavage of VE-cadherin. This results in dissolution of TJs the outcome of which is endothelial barrier breakdown.
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Affiliation(s)
- M. Y. Radeva
- Institute of Anatomy and Cell Biology; Ludwig-Maximilians-Universität München; Munich Germany
| | - J. Waschke
- Institute of Anatomy and Cell Biology; Ludwig-Maximilians-Universität München; Munich Germany
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17
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Rezaee F, Harford TJ, Linfield DT, Altawallbeh G, Midura RJ, Ivanov AI, Piedimonte G. cAMP-dependent activation of protein kinase A attenuates respiratory syncytial virus-induced human airway epithelial barrier disruption. PLoS One 2017; 12:e0181876. [PMID: 28759570 PMCID: PMC5536269 DOI: 10.1371/journal.pone.0181876] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/07/2017] [Indexed: 12/24/2022] Open
Abstract
Airway epithelium forms a barrier to the outside world and has a crucial role in susceptibility to viral infections. Cyclic adenosine monophosphate (cAMP) is an important second messenger acting via two intracellular signaling molecules: protein kinase A (PKA) and the guanidine nucleotide exchange factor, Epac. We sought to investigate effects of increased cAMP level on the disruption of model airway epithelial barrier caused by RSV infection and the molecular mechanisms underlying cAMP actions. Human bronchial epithelial cells were infected with RSV-A2 and treated with either cAMP releasing agent, forskolin, or cAMP analogs. Structure and functions of the Apical Junctional Complex (AJC) were evaluated by measuring transepithelial electrical resistance and permeability to FITC-dextran, and determining localization of AJC proteins by confocal microscopy. Increased intracellular cAMP level significantly attenuated RSV-induced disassembly of AJC. These barrier-protective effects of cAMP were due to the activation of PKA signaling and did not involve Epac activity. Increased cAMP level reduced RSV-induced reorganization of the actin cytoskeleton, including apical accumulation of an essential actin-binding protein, cortactin, and inhibited expression of the RSV F protein. These barrier-protective and antiviral-function of cAMP signaling were evident even when cAMP level was increased after the onset of RSV infection. Taken together, our study demonstrates that cAMP/PKA signaling attenuated RSV-induced disruption of structure and functions of the model airway epithelial barrier by mechanisms involving the stabilization of epithelial junctions and inhibition of viral biogenesis. Improving our understanding of the mechanisms involved in RSV-induced epithelial dysfunction and viral pathogenesis will help to develop novel anti-viral therapeutic approaches.
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Affiliation(s)
- Fariba Rezaee
- Pediatric Research Center and Pediatric Institute, Cleveland Clinic Children’s, Cleveland, Ohio, United States of America
- Pathobiology Department, Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Terri J. Harford
- Pediatric Research Center and Pediatric Institute, Cleveland Clinic Children’s, Cleveland, Ohio, United States of America
- Pathobiology Department, Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Debra T. Linfield
- Pediatric Research Center and Pediatric Institute, Cleveland Clinic Children’s, Cleveland, Ohio, United States of America
- Pathobiology Department, Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Ghaith Altawallbeh
- Pediatric Research Center and Pediatric Institute, Cleveland Clinic Children’s, Cleveland, Ohio, United States of America
- Pathobiology Department, Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Ronald J. Midura
- Biomedical Engineering Department, Lerner Research Institute, Cleveland, Ohio, United States of America
| | - Andrei I. Ivanov
- Department of Human and Molecular Genetics, Virginia Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Giovanni Piedimonte
- Pediatric Research Center and Pediatric Institute, Cleveland Clinic Children’s, Cleveland, Ohio, United States of America
- Pathobiology Department, Lerner Research Institute, Cleveland, Ohio, United States of America
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18
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Circulating Fibroblast Growth Factor-2, HIV-Tat, and Vascular Endothelial Cell Growth Factor-A in HIV-Infected Children with Renal Disease Activate Rho-A and Src in Cultured Renal Endothelial Cells. PLoS One 2016; 11:e0153837. [PMID: 27097314 PMCID: PMC4838216 DOI: 10.1371/journal.pone.0153837] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 04/05/2016] [Indexed: 01/14/2023] Open
Abstract
Renal endothelial cells (REc) are the first target of HIV-1 in the kidney. The integrity of REc is maintained at least partially by heparin binding growth factors that bind to heparan sulfate proteoglycans located on their cell surface. However, previous studies showed that the accumulation of two heparin-binding growth factors, Vascular Endothelial Cell Growth Factor-A (VEGF-A) and Fibroblast Growth Factor-2 (FGF-2), in combination with the viral protein Tat, can precipitate the progression of HIV-renal diseases. Nonetheless, very little is known about how these factors affect the behavior of REc in HIV+ children. We carried out this study to determine how VEGF-A, FGF-2, and HIV-Tat, modulate the cytoskeletal structure and permeability of cultured REc, identify key signaling pathways involved in this process, and develop a functional REc assay to detect HIV+ children affected by these changes. We found that VEGF-A and FGF-2, acting in synergy with HIV-Tat and heparin, affected the cytoskeletal structure and permeability of REc through changes in Rho-A, Src, and Rac-1 activity. Furthermore, urine samples from HIV+ children with renal diseases, showed high levels of VEGF-A and FGF-2, and induced similar changes in cultured REc and podocytes. These findings suggest that FGF-2, VEGF-A, and HIV-Tat, may affect the glomerular filtration barrier in HIV+ children through the induction of synergistic changes in Rho-A and Src activity. Further studies are needed to define the clinical value of the REc assay described in this study to identify HIV+ children exposed to circulating factors that may induce glomerular injury through similar mechanisms.
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19
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Breslin JW, Daines DA, Doggett TM, Kurtz KH, Souza-Smith FM, Zhang XE, Wu MH, Yuan SY. Rnd3 as a Novel Target to Ameliorate Microvascular Leakage. J Am Heart Assoc 2016; 5:e003336. [PMID: 27048969 PMCID: PMC4859298 DOI: 10.1161/jaha.116.003336] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Background Microvascular leakage of plasma proteins is a hallmark of inflammation that leads to tissue dysfunction. There are no current therapeutic strategies to reduce microvascular permeability. The purpose of this study was to identify the role of Rnd3, an atypical Rho family GTPase, in the control of endothelial barrier integrity. The potential therapeutic benefit of Rnd3 protein delivery to ameliorate microvascular leakage was also investigated. Methods and Results Using immunofluorescence microscopy, Rnd3 was observed primarily in cytoplasmic areas around the nuclei of human umbilical vein endothelial cells. Permeability to fluorescein isothiocyanate–albumin and transendothelial electrical resistance of human umbilical vein endothelial cell monolayers served as indices of barrier function, and RhoA, Rac1, and Cdc42 activities were determined using G‐LISA assays. Overexpression of Rnd3 significantly reduced the magnitude of thrombin‐induced barrier dysfunction, and abolished thrombin‐induced Rac1 inactivation. Depleting Rnd3 expression with siRNA significantly extended the time course of thrombin‐induced barrier dysfunction and Rac1 inactivation. Time‐lapse microscopy of human umbilical vein endothelial cells expressing GFP‐actin showed that co‐expression of mCherry‐Rnd3 attenuated thrombin‐induced reductions in local lamellipodia that accompany endothelial barrier dysfunction. Lastly, a novel Rnd3 protein delivery method reduced microvascular leakage in a rat model of hemorrhagic shock and resuscitation, assessed by both intravital microscopic observation of extravasation of fluorescein isothiocyanate–albumin from the mesenteric microcirculation, and direct determination of solute permeability in intact isolated venules. Conclusions The data suggest that Rnd3 can shift the balance of RhoA and Rac1 signaling in endothelial cells. In addition, our findings suggest the therapeutic, anti‐inflammatory potential of delivering Rnd3 to promote endothelial barrier recovery during inflammatory challenge.
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Affiliation(s)
- Jerome W Breslin
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Dayle A Daines
- Department of Biological Sciences, Old Dominion University, Norfolk, VA
| | - Travis M Doggett
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Kristine H Kurtz
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA
| | - Flavia M Souza-Smith
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA
| | - Xun E Zhang
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Mack H Wu
- Department of Surgery, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Sarah Y Yuan
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
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20
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Haasdijk RA, Den Dekker WK, Cheng C, Tempel D, Szulcek R, Bos FL, Hermkens DMA, Chrifi I, Brandt MM, Van Dijk C, Xu YJ, Van De Kamp EHM, Blonden LAJ, Van Bezu J, Sluimer JC, Biessen EAL, Van Nieuw Amerongen GP, Duckers HJ. THSD1 preserves vascular integrity and protects against intraplaque haemorrhaging in ApoE-/- mice. Cardiovasc Res 2016; 110:129-39. [PMID: 26822228 DOI: 10.1093/cvr/cvw015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 01/07/2016] [Indexed: 12/15/2022] Open
Abstract
AIMS Impairment of the endothelial barrier leads to microvascular breakdown in cardiovascular disease and is involved in intraplaque haemorrhaging and the progression of advanced atherosclerotic lesions that are vulnerable to rupture. The exact mechanism that regulates vascular integrity requires further definition. Using a microarray screen for angiogenesis-associated genes during murine embryogenesis, we identified thrombospondin type I domain 1 (THSD1) as a new putative angiopotent factor with unknown biological function. We sought to characterize the role of THSD1 in endothelial cells during vascular development and cardiovascular disease. METHODS AND RESULTS Functional knockdown of Thsd1 in zebrafish embryos and in a murine retina vascularization model induced severe haemorrhaging without affecting neovascular growth. In human carotid endarterectomy specimens, THSD1 expression by endothelial cells was detected in advanced atherosclerotic lesions with intraplaque haemorrhaging, but was absent in stable lesions, implying involvement of THSD1 in neovascular bleeding. In vitro, stimulation with pro-atherogenic factors (3% O2 and TNFα) decreased THSD1 expression in human endothelial cells, whereas stimulation with an anti-atherogenic factor (IL10) showed opposite effect. Therapeutic evaluation in a murine advanced atherosclerosis model showed that Thsd1 overexpression decreased plaque vulnerability by attenuating intraplaque vascular leakage, subsequently reducing macrophage accumulation and necrotic core size. Mechanistic studies in human endothelial cells demonstrated that THSD1 activates FAK-PI3K, leading to Rac1-mediated actin cytoskeleton regulation of adherens junctions and focal adhesion assembly. CONCLUSION THSD1 is a new regulator of endothelial barrier function during vascular development and protects intraplaque microvessels against haemorrhaging in advanced atherosclerotic lesions.
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Affiliation(s)
- Remco A Haasdijk
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Wijnand K Den Dekker
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Caroline Cheng
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands Regenerative Vascular Medicine Laboratory, Department of Nephrology and Hypertension, Division of Internal Medicine and Dermatology, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3584 CX Utrecht, 3508 GA Utrecht, The Netherlands
| | - Dennie Tempel
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Robert Szulcek
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Frank L Bos
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands Hubrecht Institute, Utrecht, The Netherlands
| | - Dorien M A Hermkens
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands Hubrecht Institute, Utrecht, The Netherlands
| | - Ihsan Chrifi
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands Regenerative Vascular Medicine Laboratory, Department of Nephrology and Hypertension, Division of Internal Medicine and Dermatology, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3584 CX Utrecht, 3508 GA Utrecht, The Netherlands
| | - Maarten M Brandt
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands Regenerative Vascular Medicine Laboratory, Department of Nephrology and Hypertension, Division of Internal Medicine and Dermatology, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3584 CX Utrecht, 3508 GA Utrecht, The Netherlands
| | - Chris Van Dijk
- Regenerative Vascular Medicine Laboratory, Department of Nephrology and Hypertension, Division of Internal Medicine and Dermatology, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3584 CX Utrecht, 3508 GA Utrecht, The Netherlands
| | - Yan Juan Xu
- Regenerative Vascular Medicine Laboratory, Department of Nephrology and Hypertension, Division of Internal Medicine and Dermatology, University Medical Center Utrecht, Heidelberglaan 100, PO Box 85500, 3584 CX Utrecht, 3508 GA Utrecht, The Netherlands
| | | | - Lau A J Blonden
- Department of Cardiology, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jan Van Bezu
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Judith C Sluimer
- Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Erik A L Biessen
- Department of Pathology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Geerten P Van Nieuw Amerongen
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Henricus J Duckers
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
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Stamatovic SM, Sladojevic N, Keep RF, Andjelkovic AV. PDCD10 (CCM3) regulates brain endothelial barrier integrity in cerebral cavernous malformation type 3: role of CCM3-ERK1/2-cortactin cross-talk. Acta Neuropathol 2015; 130:731-50. [PMID: 26385474 DOI: 10.1007/s00401-015-1479-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 10/25/2022]
Abstract
Impairment of brain endothelial barrier integrity is critical for cerebral cavernous malformation (CCM) lesion development. The current study investigates changes in tight junction (TJ) complex organization when PDCD10 (CCM3) is mutated/depleted in human brain endothelial cells. Analysis of lesions with CCM3 mutation and brain endothelial cells transfected with CCM3 siRNA (CCM3-knockdown) showed little or no increase in TJ transmembrane and scaffolding proteins mRNA expression, but proteins levels were generally decreased. CCM3-knockdown cells had a redistribution of claudin-5 and occludin from the membrane to the cytosol with no alterations in protein turnover but with diminished protein-protein interactions with ZO-1 and ZO-1 interaction with the actin cytoskeleton. The most profound effect of CCM3 mutation/depletion was on an actin-binding protein, cortactin. CCM3 depletion caused cortactin Ser-phosphorylation, dissociation from ZO-1 and actin, redistribution to the cytosol and degradation. This affected cortical actin ring organization, TJ complex stability and consequently barrier integrity, with constant hyperpermeability to inulin. A potential link between CCM3 depletion and altered cortactin was tonic activation of MAP kinase ERK1/2. ERK1/2 inhibition increased cortactin expression and incorporation into the TJ complex and improved barrier integrity. This study highlights the potential role of CCM3 in regulating TJ complex organization and brain endothelial barrier permeability.
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22
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Fu BM, Yang J, Cai B, Fan J, Zhang L, Zeng M. Reinforcing endothelial junctions prevents microvessel permeability increase and tumor cell adhesion in microvessels in vivo. Sci Rep 2015; 5:15697. [PMID: 26507779 PMCID: PMC4623601 DOI: 10.1038/srep15697] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/16/2015] [Indexed: 11/23/2022] Open
Abstract
Tumor cell adhesion to the microvessel wall is a critical step during tumor metastasis. Vascular endothelial growth factor (VEGF), a secretion of tumor cells, can increase microvessel permeability and tumor cell adhesion in the microvessel. To test the hypothesis that inhibiting permeability increase can reduce tumor cell adhesion, we used in vivo fluorescence microscopy to measure both microvessel permeability and adhesion rates of human mammary carcinoma MDA-MB-231 cells in post-capillary venules of rat mesentery under the treatment of VEGF and a cAMP analog, 8-bromo-cAMP, which can decrease microvessel permeability. By immunostaining adherens junction proteins between endothelial cells forming the microvessel wall, we further investigated the structural mechanism by which cAMP abolishes VEGF-induced increase in microvessel permeability and tumor cell adhesion. Our results demonstrate that 1) Pretreatment of microvessels with cAMP can abolish VEGF-enhanced microvessel permeability and tumor cell adhesion; 2) Tumor cells prefer to adhere to the endothelial cell junctions instead of cell bodies; 3) VEGF increases microvessel permeability and tumor cell adhesion by compromising endothelial junctions while cAMP abolishes these effects of VEGF by reinforcing the junctions. These results suggest that strengthening the microvessel wall integrity can be a potential approach to inhibiting hematogenous tumor metastasis.
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Affiliation(s)
- Bingmei M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
| | - Jinlin Yang
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
| | - Bin Cai
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
| | - Jie Fan
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
| | - Lin Zhang
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
| | - Min Zeng
- Department of Biomedical Engineering, The City College of the City University of New York, 160 Convent Ave, New York, NY 10031
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23
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Marinković G, Heemskerk N, van Buul JD, de Waard V. The Ins and Outs of Small GTPase Rac1 in the Vasculature. J Pharmacol Exp Ther 2015; 354:91-102. [PMID: 26036474 DOI: 10.1124/jpet.115.223610] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 06/01/2015] [Indexed: 12/16/2022] Open
Abstract
The Rho family of small GTPases forms a 20-member family within the Ras superfamily of GTP-dependent enzymes that are activated by a variety of extracellular signals. The most well known Rho family members are RhoA (Ras homolog gene family, member A), Cdc42 (cell division control protein 42), and Rac1 (Ras-related C3 botulinum toxin substrate 1), which affect intracellular signaling pathways that regulate a plethora of critical cellular functions, such as oxidative stress, cellular contacts, migration, and proliferation. In this review, we describe the current knowledge on the role of GTPase Rac1 in the vasculature. Whereas most recent reviews focus on the role of vascular Rac1 in endothelial cells, in the present review we also highlight the functional involvement of Rac1 in other vascular cells types, namely, smooth muscle cells present in the media and fibroblasts located in the adventitia of the vessel wall. Collectively, this overview shows that Rac1 activity is involved in various functions within one cell type at distinct locations within the cell, and that there are overlapping but also cell type-specific functions in the vasculature. Chronically enhanced Rac1 activity seems to contribute to vascular pathology; however, Rac1 is essential to vascular homeostasis, which makes Rac1 inhibition as a therapeutic option a delicate balancing act.
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Affiliation(s)
- Goran Marinković
- Department Medical Biochemistry (G.M., V.d.W.) and Department of Molecular Cell Biology (N.H., J.D.v.B.), Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Niels Heemskerk
- Department Medical Biochemistry (G.M., V.d.W.) and Department of Molecular Cell Biology (N.H., J.D.v.B.), Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jaap D van Buul
- Department Medical Biochemistry (G.M., V.d.W.) and Department of Molecular Cell Biology (N.H., J.D.v.B.), Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Vivian de Waard
- Department Medical Biochemistry (G.M., V.d.W.) and Department of Molecular Cell Biology (N.H., J.D.v.B.), Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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24
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Doggett TM, Breslin JW. Acute alcohol intoxication-induced microvascular leakage. Alcohol Clin Exp Res 2015; 38:2414-26. [PMID: 25257290 DOI: 10.1111/acer.12525] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/02/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Alcohol intoxication can increase inflammation and worsen injury, yet the mechanisms involved are not clear. We investigated whether acute alcohol intoxication increases microvascular permeability and investigated potential signaling mechanisms in endothelial cells that may be involved. METHODS Conscious rats received a 2.5 g/kg alcohol bolus via gastric catheters to produce acute intoxication. Microvascular leakage of intravenously administered fluorescein isothiocyanate (FITC)-conjugated albumin (FITC-albumin) from the mesenteric microcirculation was assessed by intravital microscopy. Endothelial-specific mechanisms were studied using cultured endothelial cell monolayers. Transendothelial electrical resistance (TER) served as an index of barrier function, before and after treatment with alcohol or its metabolite acetaldehyde. Pharmacologic agents were used to test the roles of alcohol metabolism, oxidative stress, p38 mitogen-activated protein kinase (MAPK), myosin light-chain kinase (MLCK), rho kinase (ROCK), and exchange protein activated by cAMP (Epac). VE-cadherin localization was investigated to assess junctional integrity. Rac1 and RhoA activation was assessed by ELISA assays. RESULTS Alcohol significantly increased FITC-albumin extravasation from the mesenteric microcirculation. Alcohol also significantly decreased TER and disrupted VE-cadherin organization at junctions. Acetaldehyde significantly decreased TER, but inhibition of alcohol dehydrogenase or application of a superoxide dismutase mimetic failed to prevent alcohol-induced decreases in TER. Inhibition of p38 MAPK, but not MLCK or ROCK, significantly attenuated the alcohol-induced barrier dysfunction. Alcohol rapidly decreased GTP-bound Rac1 but not RhoA during the drop in TER. Activation of Epac increased TER, but did not prevent alcohol from decreasing TER. However, activation of Epac after initiation of alcohol-induced barrier dysfunction quickly resolved TER to baseline levels. CONCLUSIONS Our results suggest that alcohol intoxication increases microvascular permeability to plasma proteins. The data also suggest the endothelial-specific mechanism involves the p38 MAPK, Rac1, and reorganization of VE-cadherin at junctions. Last, activation of Epac can quickly resolve alcohol-induced endothelial barrier dysfunction.
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Affiliation(s)
- Travis M Doggett
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana
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25
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Kobayashi K, Sato K, Kida T, Omori K, Hori M, Ozaki H, Murata T. Stromal cell-derived factor-1α/C-X-C chemokine receptor type 4 axis promotes endothelial cell barrier integrity via phosphoinositide 3-kinase and Rac1 activation. Arterioscler Thromb Vasc Biol 2014; 34:1716-22. [PMID: 24925969 DOI: 10.1161/atvbaha.114.303890] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Although stromal cell-derived factor (SDF)-1αis well known to modulate the mobilization of hematopoietic stem cells and endothelial progenitor cells, its effects on some pre-existing vascular functions remain unknown. We have investigated here the role of SDF-1αsignaling in endothelial barrier function. APPROACH AND RESULTS Treatment with SDF-1α elevated transendothelial electrical resistance and inhibited the dextran hyperpermeability elicited by thrombin in bovine aortic endothelial cells, both indicating an increase in endothelial barrier function. SDF-1α binds to 2 receptors, C-X-C chemokine receptor types 4 and 7 (CXCR4 and CXCR7). Pretreatment with a CXCR4 antagonist or CXCR4 gene depletion by small interfering RNA (siRNA) eliminated SDF-1α-induced endothelial barrier enhancement. In contrast, CXCR7 antagonist or CXCR7 gene depletion by siRNA did not influence SDF-1α-induced barrier enhancement. Pretreatment with a Gi-protein inhibitor, a phosphoinositide 3-kinase (PI3K) inhibitor, or PI3K p110γsubunit gene depletion by siRNA also inhibited SDF-1α-induced barrier enhancement significantly. Western blot analysis revealed that SDF-1α phosphorylated Akt(Ser473) in endothelial cells, suggesting PI3K activation. Immunostaining showed that treatment with SDF-1αformed a cortical actin rim, which was accompanied by Rac1 activation. In vivo, SDF-1αinhibited croton oil-induced vascular leakage indexed by dye extravasation, which is attenuated by a pretreatment with a CXCR4 antagonist. CONCLUSIONS We have identified SDF-1α as a novel suppressor of endothelial permeability. Specifically, SDF-1α stimulates the CXCR4/PI3K/Rac1 signaling pathway and the subsequent cytoskeletal rearrangement.
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Affiliation(s)
- Koji Kobayashi
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kanako Sato
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Taiki Kida
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Keisuke Omori
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masatoshi Hori
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Ozaki
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takahisa Murata
- From the Departments of Animal Radiology (K.K., K.O., T.M.) and Veterinary Pharmacology (K.S., T.K., M.H., H.O.), Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan.
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26
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ASAP1 mediates the invasive phenotype of human laryngeal squamous cell carcinoma to affect survival prognosis. Oncol Rep 2014; 31:2676-82. [PMID: 24788532 DOI: 10.3892/or.2014.3150] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 03/24/2014] [Indexed: 11/05/2022] Open
Abstract
ASAP1 helps regulate cellular structures such as actin cytoskeletal remodeling and focal adhesions that have a pivotal function in tumor progression. Overexpression of ASAP1 has proven to be a malignant indicator for a variety of tumors. To further determine the potential involvement of ASAP1 in laryngeal squamous cell carcinoma (LSCC), we evaluated the expression levels of ASAP1 by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry in tissue samples of 64 LSCC patients. We then analyzed and correlated the results with clinicopathological features. Furthermore, we used small interfering RNA (siRNA) to inhibit ASAP1 expression in vitro. The potential function of ASAP1 in invasiveness was evaluated in the Hep-2 LSCC cell line. Kaplan-Meier method was utilized to determine the association of ASAP1 expression with survival of patients. We showed that ASAP1 was upregulated in primary LSCC tumors and was correlated with lymph node metastasis and clinical tumor stage. Similarly, higher levels of ASAP1 were detected in the Hep-2 cell line compared to the 16 human bronchial epithelial (16HBE) cell line. ASAP1 expression was downregulated by lentiviral vector transfection containing siRNA in vitro. The invasive potential of these cells was found to be significantly suppressed, while expression levels of Rac1 and Cdc42 positively correlated with the inhibition of ASAP1 expression. In Kaplan-Meier overall survival curves, higher ASAP1 mRNA levels were found to be associated with a shorter progression-free survival trend. Based on these results, ASAP1 appears to contribute to the malignant mechanism of LSCC and may represent a significant prognostic marker for LSCC patients.
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Amado-Azevedo J, Valent ET, Van Nieuw Amerongen GP. Regulation of the endothelial barrier function: a filum granum of cellular forces, Rho-GTPase signaling and microenvironment. Cell Tissue Res 2014; 355:557-76. [PMID: 24633925 DOI: 10.1007/s00441-014-1828-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/24/2014] [Indexed: 12/20/2022]
Abstract
Although the endothelium is an extremely thin single-cell layer, it performs exceedingly well in preventing blood fluids from leaking into the surrounding tissues. However, specific pathological conditions can affect this cell layer, compromising the integrity of the barrier. Vascular leakage is a hallmark of many cardiovascular diseases and despite its medical importance, no specialized therapies are available to prevent it or reduce it. Small guanosine triphosphatases (GTPases) of the Rho family are known to be key regulators of various aspects of cell behavior and studies have shown that they can exert both positive and negative effects on endothelial barrier integrity. Moreover, extracellular matrix stiffness has now been implicated in the regulation of Rho-GTPase signaling, which has a direct impact on the integrity of endothelial junctions. However, knowledge about both the precise mechanism of this regulation and the individual contribution of the specific regulatory proteins remains fragmentary. In this review, we discuss recent findings concerning the balanced activities of Rho-GTPases and, in particular, aspects of the regulation of the endothelial barrier. We highlight the role of Rho-GTPases in the intimate relationships between biomechanical forces, microenvironmental influences and endothelial intercellular junctions, which are all interwoven in a beautiful filigree-like fashion.
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Affiliation(s)
- Joana Amado-Azevedo
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van den Boechorststraat 7, 1081BT, Amsterdam, The Netherlands
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28
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Schlegel N, Waschke J. cAMP with other signaling cues converges on Rac1 to stabilize the endothelial barrier- a signaling pathway compromised in inflammation. Cell Tissue Res 2013; 355:587-96. [PMID: 24322391 DOI: 10.1007/s00441-013-1755-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 10/31/2013] [Indexed: 12/20/2022]
Abstract
cAMP is one of the most potent signaling molecules to stabilize the endothelial barrier, both under resting conditions as well as under challenge of barrier-destabilizing mediators. The two main signaling axes downstream of cAMP are activation of protein kinase A (PKA) as well as engagement of exchange protein directly activated by cAMP (Epac) and its effector GTPase Rap1. Interestingly, both pathways activate GTP exchange factors for Rac1, such as Tiam1 and Vav2 and stabilize the endothelial barrier via Rac1-mediated enforcement of adherens junctions and strengthening of the cortical actin cytoskeleton. On the level of Rac1, cAMP signaling converges with other barrier-enhancing signaling cues induced by sphingosine-1-phosphate (S1P) and angiopoietin-1 (Ang1) rendering Rac1 as an important signaling hub. Moreover, activation of Rap1 and inhibition of RhoA also contribute to barrier stabilization, emphasizing that regulation of small GTPases is a central mechanism in this context. The relevance of cAMP/Rac1-mediated barrier protection under pathophysiologic conditions can be concluded from data showing that inflammatory mediators causing multi-organ failure in systemic inflammation or sepsis interfere with this signaling axis on the level of cAMP or Rac1. This is in line with the well-known efficacy of cAMP to abrogate the barrier breakdown in response to most barrier-compromising stimuli. New is the notion that the tight endothelial barrier under resting conditions is maintained by (1) continuous cAMP formation induced by hormones such as epinephrine or (2) by activation of Rac1 downstream of S1P that is secreted by erythrocytes and activated platelets.
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Affiliation(s)
- Nicolas Schlegel
- Department of General-, Visceral, Vascular and Pediatric surgery, University Hospital Wuerzburg, Oberduerrbacherstrasse 6, 97080, Wuerzburg, Germany
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29
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Abstract
This article examines the role of the endothelial cytoskeleton in the lung's ability to restrict fluid and protein to vascular space at normal vascular pressures and thereby to protect lung alveoli from lethal flooding. The barrier properties of microvascular endothelium are dependent on endothelial cell contact with other vessel-wall lining cells and with the underlying extracellular matrix (ECM). Focal adhesion complexes are essential for attachment of endothelium to ECM. In quiescent endothelial cells, the thick cortical actin rim helps determine cell shape and stabilize endothelial adherens junctions and focal adhesions through protein bridges to actin cytoskeleton. Permeability-increasing agonists signal activation of "small GTPases" of the Rho family to reorganize the actin cytoskeleton, leading to endothelial cell shape change, disassembly of cortical actin rim, and redistribution of actin into cytoplasmic stress fibers. In association with calcium- and Src-regulated myosin light chain kinase (MLCK), stress fibers become actinomyosin-mediated contractile units. Permeability-increasing agonists stimulate calcium entry and induce tyrosine phosphorylation of VE-cadherin (vascular endothelial cadherin) and β-catenins to weaken or pull apart endothelial adherens junctions. Some permeability agonists cause latent activation of the small GTPases, Cdc42 and Rac1, which facilitate endothelial barrier recovery and eliminate interendothelial gaps. Under the influence of Cdc42 and Rac1, filopodia and lamellipodia are generated by rearrangements of actin cytoskeleton. These motile evaginations extend endothelial cell borders across interendothelial gaps, and may initiate reannealing of endothelial junctions. Endogenous barrier protective substances, such as sphingosine-1-phosphate, play an important role in maintaining a restrictive endothelial barrier and counteracting the effects of permeability-increasing agonists.
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Affiliation(s)
- Stephen M Vogel
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois, USA.
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30
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Onodera H, Arito M, Sato T, Ito H, Hashimoto T, Tanaka Y, Kurokawa MS, Okamoto K, Suematsu N, Kato T. Novel effects of edaravone on human brain microvascular endothelial cells revealed by a proteomic approach. Brain Res 2013; 1534:87-94. [PMID: 23958343 DOI: 10.1016/j.brainres.2013.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 08/09/2013] [Indexed: 12/20/2022]
Abstract
Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a free radical scavenger used for acute ischemic stroke. However, it is not known whether edaravone works only as a free radical scavenger or possess other pharmacological actions. Therefore, we elucidated the effects of edaravone on human brain microvascular endothelial cells (HBMECs) by 2 dimensional fluorescence difference gel electrophoresis (2D-DIGE). We found 38 protein spots the intensity of which was significantly altered 1.3 fold on average (p< 0.05) by the edaravone treatment and successfully identified 17 proteins of those. Four of those 17 proteins were cytoskeleton proteins or cytoskeleton-regulating proteins. Therefore, we subsequently investigated the change of size and shape of the cells, the actin network, and the tight junction of HBMEC by immunocytochemistry. As a result, most edaravone-treated HBMECs became larger and rounder compared with those that were not treated. Furthermore, edaravone-treated HBMECs formed gathering zona occludens (ZO)-1, a tight junction protein, along the junction of the cells. In addition, we found that edaravone suppressed interleukin (IL)-1β-induced secretion of monocyte chemoattractant protein-1 (MCP-1), which was reported to increase cell permeability. We found a novel function of edaravone is the promotion of tight junction formations of vascular endothelial cells partly via the down-regulation of MCP-1 secretion. These data provide fundamental and useful information in the clinical use of edaravone in patients with cerebral vascular diseases.
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Affiliation(s)
- Hidetaka Onodera
- Clinical Proteomics and Molecular Medicine, St. Marianna University Graduate School of Medicine, 2-16-1 Sugao, Miyamae, Kawasaki, Kanagawa 216-8512, Japan; Department of Neurosurgery, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae, Kawasaki, Kanagawa 216-8512, Japan
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31
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Curry FRE, Adamson RH. Tonic regulation of vascular permeability. Acta Physiol (Oxf) 2013; 207:628-49. [PMID: 23374222 PMCID: PMC4054936 DOI: 10.1111/apha.12076] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 01/10/2013] [Accepted: 01/28/2013] [Indexed: 12/30/2022]
Abstract
Our major theme is that the layered structure of the endothelial barrier requires continuous activation of signalling pathways regulated by sphingosine-1-phosphate (S1P) and intracellular cAMP. These pathways modulate the adherens junction, continuity of tight junction strands, and the balance of synthesis and degradation of glycocalyx components. We evaluate recent evidence that baseline permeability is maintained by constant activity of mechanisms involving the small GTPases Rap1 and Rac1. In the basal state, the barrier is compromised when activities of the small GTPases are reduced by low S1P supply or delivery. With inflammatory stimulus, increased permeability can be understood in part as the action of signalling to reduce Rap1 and Rac1 activation. With the hypothesis that microvessel permeability and selectivity under both normal and inflammatory conditions are regulated by mechanisms that are continuously active, it follows that when S1P or intracellular cAMP are elevated at the time of inflammatory stimulus, they can buffer changes induced by inflammatory agents and maintain normal barrier stability. When endothelium is exposed to inflammatory conditions and subsequently exposed to elevated S1P or intracellular cAMP, the same processes restore the functional barrier by first re-establishing the adherens junction, then modulating tight junctions and glycocalyx. In more extreme inflammatory conditions, loss of the inhibitory actions of Rac1-dependent mechanisms may promote expression of more inflammatory endothelial phenotypes by contributing to the up-regulation of RhoA-dependent contractile mechanisms and the sustained loss of surface glycocalyx allowing access of inflammatory cells to the endothelium.
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Affiliation(s)
- F-R E Curry
- Department of Physiology & Membrane Biology, School of Medicine, University of California at Davis, Davis, CA 95616, USA.
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32
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Shao M, Yue Y, Sun GY, You QH, Wang N, Zhang D. Caveolin-1 regulates Rac1 activation and rat pulmonary microvascular endothelial hyperpermeability induced by TNF-α. PLoS One 2013; 8:e55213. [PMID: 23383114 PMCID: PMC3559378 DOI: 10.1371/journal.pone.0055213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 12/19/2012] [Indexed: 12/20/2022] Open
Abstract
A multiplicity of vital cellular and tissue level functions are controlled by caveolin-1 and it is considered to be an important candidate for targeted therapeutics. Rac1-cortactin signaling plays an important role in maintaining the functions of the endothelial barrier in microvascular endothelial cells. The activity of Rac1 has been shown to be regulated by caveolin-1. Therefore, the present study investigated the consequences of down-regulating caveolin-1 and the subsequent changes in activity of Rac1 and the endothelial barrier functions in primary rat pulmonary microvascular endothelial cells (RPMVECs). RPMVECs were transfected with a small hairpin RNA duplex to down-regulate caveolin-1 expression. This procedure significantly increased the activity of Rac1. Moreover, down-regulation of caveolin-1 attenuated TNF-α-induced decrease in TER, increase in the flux of FITC-BSA and the disappearance of cortactin from the cell periphery in RPMVEC. Rac1 inhibitors significantly abolished this barrier-protective effect induced by down-regulation of caveolin-1 in response to TNF-α in RPMVECs. In conclusion, our data suggest a mechanism for the regulation of Rac1 activity by caveolin-1, with consequences for activation of endothelial cells in response to TNF-α.
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Affiliation(s)
- Min Shao
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
- Department of Critical Care Medicine, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui, People’s Republic of China
| | - Yang Yue
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
| | - Geng-Yun Sun
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
- * E-mail:
| | - Qing-Hai You
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
| | - Nan Wang
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
| | - Dan Zhang
- Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People’s Republic of China
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Curry FE, Clark JF, Adamson RH. Erythrocyte-derived sphingosine-1-phosphate stabilizes basal hydraulic conductivity and solute permeability in rat microvessels. Am J Physiol Heart Circ Physiol 2012; 303:H825-34. [PMID: 22865384 PMCID: PMC3469701 DOI: 10.1152/ajpheart.00181.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 07/25/2012] [Indexed: 11/22/2022]
Abstract
Exogenous sphingosine-1-phosphate (S1P), a lipid mediator in blood, attenuates acute microvascular permeability increases via receptor S1P1 to stabilize the endothelium. To evaluate the contribution of erythrocytes as an endogenous source of S1P to the regulation of basal permeability, we measured permeability coefficients in intact individually perfused venular microvessels of rat mesentery. This strategy also enabled the contributions of other endogenous S1P sources to be evaluated. Apparent permeability coefficients (P(S)) to albumin and α-lactalbumin and the hydraulic conductivity of mesenteric microvessels were measured in the presence or absence of rat erythrocytes or rat erythrocyte-conditioned perfusate. Rat erythrocytes added to the perfusate were the principal source of S1P in these microvessels. Basal P(S) to albumin was stable and typical of blood-perfused microvessels (mean 0.5 × 10(-6) cm/s) when erythrocytes or erythrocyte-conditioned perfusates were present. When they were absent, P(S) to albumin or α-lactalbumin increased up to 40-fold (over 10 min). When exogenous S1P was added to perfusates, permeability returned to levels comparable with those seen in the presence of erythrocytes. Addition of SEW 2871, an agonist specific for S1P1, in the absence of red blood cells reduced P(S)(BSA) (40-fold reduction) toward basal. The specific S1P1 receptor antagonist (W-146) reversed the stabilizing action of erythrocytes and increased permeability (27-fold increase) in a manner similar to that seen in the absence of erythrocytes. Erythrocytes are a primary source of S1P that maintains normal venular microvessel permeability. Absence of erythrocytes or conditioned perfusate in in vivo and in vitro models of endothelial barriers elevates basal permeability.
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Affiliation(s)
- F E Curry
- Department of Physiology and Membrane Biology, School of Medicine, University of California at Davis, Davis, CA 95616, USA.
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34
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Adamson RH, Sarai RK, Clark JF, Altangerel A, Thirkill TL, Curry FE. Attenuation by sphingosine-1-phosphate of rat microvessel acute permeability response to bradykinin is rapidly reversible. Am J Physiol Heart Circ Physiol 2012; 302:H1929-35. [PMID: 22427519 DOI: 10.1152/ajpheart.00614.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
To evaluate the hypothesis that sphingosine-1-phosphate (S1P) and cAMP attenuate increased permeability of individually perfused mesenteric microvessels through a common Rac1-dependent pathway, we measured the attenuation of the peak hydraulic conductivity (L(p)) in response to the inflammatory agent bradykinin (BK) by either S1P or cAMP. We varied the extent of exposure to each agent (test) and measured the ratio L(p)(test)/L(p)(BK alone) for each vessel (anesthetized rats). S1P (1 μM) added at the same time as BK (concurrent, no pretreatment) was as effective to attenuate the response to BK (L(p) ratio: 0.14 ± 0.05; n = 5) as concurrent plus pretreatment with S1P for 30 min (L(p) ratio: 0.26 ± 0.06; n = 11). The same pretreatment with S1P, but with no concurrent S1P, caused no inhibition of the BK response (L(p) ratio 1.07 ± 0.11; n = 8). The rapid on and off action of S1P demonstrated by these results was in contrast to cAMP-dependent changes induced by rolipram and forskolin (RF), which developed more slowly, lasted longer, and resulted in partial inhibition when given either as pretreatment or concurrent with BK. In cultured endothelium, there was no Rac activation or peripheral cortactin localization at 1 min with RF, but cortactin localization and Rac activation were maximal at 1 min with S1P. When S1P was removed, Rac activation returned to control within 2 min. Because of such differing time courses, S1P and cAMP are unlikely to act through fully common effector mechanisms.
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Affiliation(s)
- R H Adamson
- Department of Physiology and Membrane Biology, School of Medicine, University of California at Davis, Davis, CA 95616, USA.
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Spindler V, Waschke J. Beta-adrenergic stimulation contributes to maintenance of endothelial barrier functions under baseline conditions. Microcirculation 2011; 18:118-27. [PMID: 21166930 DOI: 10.1111/j.1549-8719.2010.00072.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVES cAMP signaling within the endothelium is known to reduce paracellular permeability and to protect against loss of barrier functions under various pathological conditions. Because activation of β-adrenergic receptors elevates cellular cAMP, we tested whether β-adrenergic receptor signaling contributes to the maintenance of baseline endothelial barrier properties. METHODS We compared hydraulic conductivity of rat postcapillary venules in vivo with resistance measurements and with reorganization of endothelial adherens junctions in cultured microvascular endothelial cells downstream of β-adrenergic receptor-mediated changes of cAMP levels. RESULTS Inhibition of β-adrenergic receptors by propranolol increased hydraulic conductivity, reduced both cAMP levels and TER of microvascular endothelial cell monolayers and induced fragmentation of VE-cadherin staining. In contrast, activation by epinephrine both increased cAMP levels and TER and resulted in linearized VE-cadherin distribution, however this was not sufficient to block barrier-destabilization by propranolol. Similarly, PDE inhibition did not prevent propranolol-induced TER reduction and VE-cadherin reorganization whereas increased cAMP formation by AC activation enhanced endothelial barrier functions under baseline conditions and under conditions of propranolol treatment. CONCLUSIONS Our results indicate that generation of cAMP mediated by activation of β-adrenergic receptor signaling contributes to the maintenance of endothelial barrier properties under baseline conditions.
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Affiliation(s)
- Volker Spindler
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, Würzburg, Germany
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Profirovic J, Han J, Andreeva AV, Neamu RF, Pavlovic S, Vogel SM, Walter U, Voyno-Yasenetskaya TA. Vasodilator-stimulated phosphoprotein deficiency potentiates PAR-1-induced increase in endothelial permeability in mouse lungs. J Cell Physiol 2011; 226:1255-64. [PMID: 20945373 PMCID: PMC3043150 DOI: 10.1002/jcp.22453] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is implicated in the protection of the endothelial barrier in vitro and in vivo. The function of VASP in thrombin signaling in the endothelial cells (ECs) is not known. For the first time we studied the effects of VASP deficiency on EC permeability and pulmonary vascular permeability in response to thrombin receptor stimulation. We provided the evidence that VASP deficiency potentiates the increase in endothelial permeability induced by activation of thrombin receptor in cultured human umbilical vein endothelial cells (HUVECs) and isolated mouse lungs. Using transendothelial resistance measurement, we showed that siRNA-mediated VASP downregulation in HUVECs leads to a potentiation of thrombin- and protease-activated receptor 1 (PAR-1) agonist-induced increase in endothelial permeability. Compared to control cells, VASP-deficient HUVECs had delayed endothelial junctional reassembly and abrogated VE-cadherin cytoskeletal anchoring in the recovery phase after thrombin stimulation, as demonstrated by immunofluorescence studies and cell fractionation analysis, respectively. Measurement of the capillary filtration coefficient in isolated mouse lungs demonstrated that VASP(-/-) mice have increased microvascular permeability in response to infusion with PAR-1 agonist compared to wild type mice. Lack of VASP led to decreased Rac1 activation both in VASP-deficient HUVECs after thrombin stimulation and VASP(-/-) mouse lungs after PAR-1 agonist infusion, indicating that VASP effects on thrombin signaling may be correlated with changes in Rac1 activity. This study demonstrates that VASP may play critical and complex role in the regulation of thrombin-dependent disruption of the endothelial barrier function.
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Affiliation(s)
- Jasmina Profirovic
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA.
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Sayner SL. Emerging themes of cAMP regulation of the pulmonary endothelial barrier. Am J Physiol Lung Cell Mol Physiol 2011; 300:L667-78. [PMID: 21335524 DOI: 10.1152/ajplung.00433.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The presence of excess fluid in the interstitium and air spaces of the lung presents severe restrictions to gas exchange. The pulmonary endothelial barrier regulates the flux of fluid and plasma proteins from the vascular space into the underlying tissue. The integrity of this endothelial barrier is dynamically regulated by transitions in cAMP (3',5'-cyclic adenosine monophosphate), which are synthesized in discrete subcellular compartments. Cyclic AMP generated in the subplasma membrane compartment acts through PKA and Epac (exchange protein directly activated by cAMP) to tighten cell adhesions, strengthen cortical actin, reduce actomyosin contraction, and decrease permeability. Confining cAMP within the subplasma membrane space is critical to its barrier-protective properties. When cAMP escapes the near membrane compartment and gains access to the cytosolic compartment, or when soluble adenylyl cyclases generate cAMP within the cytosolic compartment, this second messenger activates established cytosolic cAMP signaling cascades to perturb the endothelial barrier through PKA-mediated disruption of microtubules. Thus the concept of cAMP compartmentalization in endothelial barrier regulation is gaining momentum and new possibilities are being unveiled for cytosolic cAMP signaling with the emergence of the bicarbonate-regulated mammalian soluble adenylyl cyclase (sAC or AC10).
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Affiliation(s)
- Sarah L Sayner
- Dept. of Cell Biology and Neuroscience, Member, Center for Lung Biology, College of Medicine, Univ. of South Alabama, Mobile, AL 36688, USA.
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Adamson RH, Sarai RK, Altangerel A, Thirkill TL, Clark JF, Curry FRE. Sphingosine-1-phosphate modulation of basal permeability and acute inflammatory responses in rat venular microvessels. Cardiovasc Res 2010; 88:344-51. [PMID: 20542878 DOI: 10.1093/cvr/cvq184] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
AIMS Although several cultured endothelial cell studies indicate that sphingosine-1-phosphate (S1P), via GTPase Rac1 activation, enhances endothelial barriers, very few in situ studies have been published. We aimed to further investigate the mechanisms whereby S1P modulates both baseline and increased permeability in intact microvessels. METHODS AND RESULTS We measured attenuation by S1P of platelet-activating factor (PAF)- or bradykinin (Bk)-induced hydraulic conductivity (L(p)) increase in mesenteric microvessels of anaesthetized rats. S1P alone (1-5 µM) attenuated by 70% the acute L(p) increase due to PAF or Bk. Immunofluorescence methods in the same vessels under identical experimental conditions showed that Bk or PAF stimulated the loss of peripheral endothelial cortactin and rearrangement of VE-cadherin and occludin. Our results are the first to show in intact vessels that S1P pre-treatment inhibited rearrangement of VE-cadherin and occludin induced by PAF or Bk and preserved peripheral cortactin. S1P (1-5 µM, 30 min) did not increase baseline L(p). However, 10 µM S1P (60 min) increased L(p) two-fold. CONCLUSION Our results conform to the hypothesis that S1P inhibits acute permeability increase in association with enhanced stabilization of peripheral endothelial adhesion proteins. These results support the idea that S1P can be useful to attenuate inflammation by enhancing endothelial adhesion through activation of Rac-dependent pathways.
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Affiliation(s)
- Roger H Adamson
- Department of Physiology and Membrane Biology, School of Medicine, University of California, 1 Shields Avenue, Davis, CA 95616, USA.
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Cardoso FL, Brites D, Brito MA. Looking at the blood-brain barrier: molecular anatomy and possible investigation approaches. ACTA ACUST UNITED AC 2010; 64:328-63. [PMID: 20685221 DOI: 10.1016/j.brainresrev.2010.05.003] [Citation(s) in RCA: 410] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 05/18/2010] [Accepted: 05/19/2010] [Indexed: 12/17/2022]
Abstract
The blood-brain barrier (BBB) is a dynamic and complex interface between blood and the central nervous system that strictly controls the exchanges between the blood and brain compartments, therefore playing a key role in brain homeostasis and providing protection against many toxic compounds and pathogens. In this review, the unique properties of brain microvascular endothelial cells and intercellular junctions are examined. The specific interactions between endothelial cells and basement membrane as well as neighboring perivascular pericytes, glial cells and neurons, which altogether constitute the neurovascular unit and play an essential role in both health and function of the central nervous system, are also explored. Some relevant pathways across the endothelium, as well as mechanisms involved in the regulation of BBB permeability, and the emerging role of the BBB as a signaling interface are addressed as well. Furthermore, we summarize some of the experimental approaches that can be used to monitor BBB properties and function in a variety of conditions and have allowed recent advances in BBB knowledge. Elucidation of the molecular anatomy and dynamics of the BBB is an essential step for the development of new strategies directed to maintain or restore BBB integrity and barrier function and ultimately preserve the delicate interstitial brain environment.
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Affiliation(s)
- Filipa Lourenço Cardoso
- Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
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Terry S, Nie M, Matter K, Balda MS. Rho signaling and tight junction functions. Physiology (Bethesda) 2010; 25:16-26. [PMID: 20134025 DOI: 10.1152/physiol.00034.2009] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tight junctions are heteromeric protein complexes that act as signaling centers by mediating the bidirectional transmission of information between the environment and the cell interior to control paracellular permeability and differentiation. Insight into tight junction-associated signaling mechanisms is of fundamental importance for our understanding of the physiology of epithelia and endothelia in health and disease.
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Affiliation(s)
- Steve Terry
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, London, United Kingdom
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Gündüz D, Thom J, Hussain I, Lopez D, Härtel FV, Erdogan A, Grebe M, Sedding D, Piper HM, Tillmanns H, Noll T, Aslam M. Insulin stabilizes microvascular endothelial barrier function via phosphatidylinositol 3-kinase/Akt-mediated Rac1 activation. Arterioscler Thromb Vasc Biol 2010; 30:1237-45. [PMID: 20339116 DOI: 10.1161/atvbaha.110.203901] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Insulin is a key regulator of metabolism, but it also confers protective effects on the cardiovascular system. Here, we analyze the mechanism by which insulin stabilizes endothelial barrier function. METHODS AND RESULTS Insulin reduced basal and antagonized tumor necrosis factor-alpha-induced macromolecule permeability of rat coronary microvascular endothelial monolayers. It also abolished reperfusion-induced vascular leakage in isolated-perfused rat hearts. Insulin induced dephosphorylation of the regulatory myosin light chains, as well as translocation of actin and vascular endothelial (VE)-cadherin to cell borders, indicating a reduction in contractile activation and stabilization of cell adhesion structures. These protective effects were blocked by genistein or Hydroxy-2-naphthalenylmethylphosphonic acid tris acetoxymethyl ester (HNMPA-[AM](3)), a pan-tyrosine-kinase or specific insulin-receptor-kinase inhibitor, respectively. Insulin stimulated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and NO production, and it activated Rac1. Inhibition of PI3K/Akt abrogated Rac1 activation and insulin-induced barrier protection, whereas inhibition of the endothelial nitric oxide synthase/soluble guanylyl cyclase pathway partially inhibited them. Inhibition of Rac1 abrogated the assembly of actin at cell borders. Accordingly, it abolished the protective effect of insulin on barrier function of the cultured endothelial monolayer, as well as the intact coronary system of ischemic-reperfused hearts. CONCLUSIONS Insulin stabilizes endothelial barrier via inactivation of the endothelial contractile machinery and enhancement of cell-cell adhesions. These effects are mediated via PI3K/Akt- and NO/cGMP-induced Rac1 activation.
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Affiliation(s)
- Dursun Gündüz
- Zentrum für Innere Medizin, Abteilung für Kardiologie und Angiologie, Universitätsklinikum Giessen und Marburg GmbH, Klinikstrasse 36, D-35392 Giessen, Germany.
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Schlegel N, Waschke J. Vasodilator-stimulated phosphoprotein: crucial for activation of Rac1 in endothelial barrier maintenance. Cardiovasc Res 2010; 87:1-3. [PMID: 20308204 DOI: 10.1093/cvr/cvq093] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Spindler V, Schlegel N, Waschke J. Role of GTPases in control of microvascular permeability. Cardiovasc Res 2010; 87:243-53. [DOI: 10.1093/cvr/cvq086] [Citation(s) in RCA: 273] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Nandy D, Asmann YW, Mukhopadhyay D, Basu A. Role of AKT-glycogen synthase kinase axis in monocyte activation in human beings with and without type 2 diabetes. J Cell Mol Med 2009; 14:1396-407. [PMID: 19754670 PMCID: PMC2912967 DOI: 10.1111/j.1582-4934.2009.00900.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Monocyte activation by chemokines is a vital trigger for initiation of atherosclerotic process. Circulating levels of platelet activating factor (PAF), a recognized chemokine, is known to be increased in type 2 diabetes that is linked to accelerated atherosclerosis. To explore the molecular basis we examined the signalling pathways involved in PAF induced monocyte activation. PAF increased migration in monocytes obtained from THP-1 cells, nondiabetic and diabetic subjects. This effect was blocked by AKT inhibition. It did so by phosphorylation of glycogen synthase kinase (GSK)-3βS9, which was completely blocked by AKT inhibition. Additionally, PAF induced GSK-3β phosphorylation was linked to Rac-1 activation and Rho-A inactivation leading to migration. Paradoxically, inhibition of GSK-3β phosphorylation also augmented monocyte migration in THP-1, ND and diabetic monocytes through phosphorylation of AKT and activation of Rho-A that was independent of GSK. This was validated when (i) overexpression of dominant negative mutants of Rho-A reversed GSK inhibitor induced monocyte migration and (ii) AKT inhibition blocked GSK inhibitor induced Rho-A activity. Constitutively active ARAP3 (Rho-GAP) appears to have a regulatory role in monocyte activity during GSK inhibition. Finally, inhibition of monocyte GSK-3β activity (by inhibitors and genetic manipulation) led to enhanced migration in diabetes compared to persons without diabetes. We conclude that diabetic monocytes show increased migratory capacity in response to GSK-3β inhibition. GSK inhibitors developed to treat the metabolic complications of diabetes should therefore be used with caution.
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Affiliation(s)
- Debashis Nandy
- Department of Biochemistry & Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA
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Baumer Y, Spindler V, Werthmann RC, Bünemann M, Waschke J. Role of Rac 1 and cAMP in endothelial barrier stabilization and thrombin-induced barrier breakdown. J Cell Physiol 2009; 220:716-26. [PMID: 19472214 DOI: 10.1002/jcp.21819] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Barrier stabilizing effects of cAMP as well as of the small GTPase Rac 1 are well established. Moreover, it is generally believed that permeability-increasing mediators such as thrombin disrupt endothelial barrier functions primarily via activation of Rho A. In this study, we provide evidence that decrease of both cAMP levels and of Rac 1 activity contribute to thrombin-mediated barrier breakdown. Treatment of human dermal microvascular endothelial cells (HDMEC) with Rac 1-inhibitor NSC-23766 decreased transendothelial electrical resistance (TER) and caused intercellular gap formation. These effects were reversed by addition of forskolin/rolipram (F/R) to increase intracellular cAMP but not by the cAMP analogue 8-pCPT-2'-O-Methyl-cAMP (O-Me-cAMP) which primarily stimulates protein kinase A (PKA)-independent signaling via Epac/Rap 1. However, both F/R and O-Me-cAMP did not increase TER above control levels in the presence of NSC-23766 in contrast to experiments without Rac 1 inhibition. Because Rac 1 was required for maintenance of barrier functions as well as for cAMP-mediated barrier stabilization, we tested the role of Rac 1 and cAMP in thrombin-induced barrier breakdown. Thrombin-induced drop of TER and intercellular gap formation were paralleled by a rapid decrease of cAMP as revealed by fluorescence resonance energy transfer (FRET). The efficacy of F/R or O-Me-cAMP to block barrier-destabilizing effects of thrombin was comparable to Y27632-induced inhibition of Rho kinase but was blunted when Rac 1 was inactivated by NSC-23766. Taken together, these data indicate that decrease of cAMP and Rac 1 activity may be an important step in inflammatory barrier disruption.
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Affiliation(s)
- Y Baumer
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg 97070, Germany
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Schlegel N, Waschke J. Impaired integrin-mediated adhesion contributes to reduced barrier properties in VASP-deficient microvascular endothelium. J Cell Physiol 2009; 220:357-66. [PMID: 19347869 DOI: 10.1002/jcp.21772] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Recent studies point to a significant role of vasodilator-stimulated phosphoprotein (VASP) in the maintenance of endothelial barrier functions in vivo and in vitro. Moreover, it has been reported that VASP is required for activation of the small GTPase Rac 1. However, little is known whether VASP is involved in the regulation of cell adhesion molecules that are critical for maintenance of the endothelial barrier. Here we demonstrate that impaired barrier properties in VASP-deficient (VASP-/-) microvascular myocardial endothelial cells (MyEnd) correlated with both impaired integrin-mediated adhesion as revealed by laser tweezer trapping and reduced integrin-dependent cell migration. This was paralleled by reduction of focal adhesions at the cell periphery as well as of beta(1)-integrin and VE-cadherin cytoskeletal anchorage. Incubation of MyEnd VASP wt with RGD peptide to block interaction of integrins with extracellular matrix (ECM) reduced barrier properties and Rac 1 activity in wt endothelial monolayers mimicking the situation in VASP (-/-) cells under resting conditions. Moreover, cAMP-mediated Rac 1 activation was reduced under conditions of impaired integrin-mediated adhesion in wt cells and cAMP-induced increase in VE-cadherin cytoskeletal anchorage was abolished in VASP (-/-) endothelium. In summary, these data indicate that VASP is required for integrin-mediated adhesion which stabilizes endothelial barrier properties at least in part by facilitating Rac 1 activation.
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Affiliation(s)
- Nicolas Schlegel
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
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Popoff MR, Geny B. Multifaceted role of Rho, Rac, Cdc42 and Ras in intercellular junctions, lessons from toxins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:797-812. [PMID: 19366594 DOI: 10.1016/j.bbamem.2009.01.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 01/20/2009] [Accepted: 01/22/2009] [Indexed: 12/20/2022]
Abstract
Tight junctions (TJs) and adherens junctions (AJs) are dynamic structures linked to the actin cytoskeleton, which control the paracellular permeability of epithelial and endothelial barriers. TJs and AJs are strictly regulated in a spatio-temporal manner by a complex signaling network, including Rho/Ras-GTPases, which have a pivotal role. Rho preferentially regulates TJs by controlling the contraction of apical acto-myosin filaments, whereas Rac/Cdc42 mainly coordinate the assembly-disassembly of AJ components. However, a subtle balance of Rho/Ras-GTPase activity and interplay between these molecules is required to maintain an optimal organization and function of TJs and AJs. Conversely, integrity of intercellular junctions generates signals through Rho-GTPases, which are involved in the regulation of multiple cellular processes. Rho/Ras-GTPases and the control of intercellular junctions are the target of various bacterial toxins responsible for severe diseases in man and animals, and are part of their mechanism of action. This review focuses on the regulation of TJs and AJs by Rho/Ras-GTPases through molecular approaches and bacterial toxins.
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Affiliation(s)
- Michel R Popoff
- Institut Pasteur, Unité des Bactéries anaérobies et Toxines, 75724 Paris cedex151, France.
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Lipopolysaccharide-induced endothelial barrier breakdown is cyclic adenosine monophosphate dependent in vivo and in vitro. Crit Care Med 2009; 37:1735-43. [PMID: 19325485 DOI: 10.1097/ccm.0b013e31819deb6a] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine whether cyclic adenosine monophosphate (cAMP) is critically involved in lipopolysaccharide (LPS)-induced breakdown of endothelial barrier functions in vivo and in vitro. DESIGN Experimental laboratory research. SETTING Research laboratory. SUBJECTS Wistar rats and cultured human microvascular endothelial cells. INTERVENTION Permeability measurements in single postcapillary venules in vivo and permeability measurements and cell biology techniques in vitro. MEASUREMENTS AND RESULTS We demonstrate that within 120 minutes LPS increased endothelial permeability in rat mesenteric postcapillary venules in vivo and caused a barrier breakdown in human dermal microvascular endothelial cells in vitro. This was associated with the formation of large intercellular gaps and fragmentation of vascular endothelial cadherin immunostaining. Furthermore, claudin 5 immunostaining at cell borders was drastically reduced after LPS treatment. Interestingly, activity of the small GTPase Rho A, which has previously been suggested to mediate the LPS-induced endothelial barrier breakdown, was not increased after 2 hours. However, activity of Rac 1, which is known to be important for maintenance of endothelial barrier functions, was significantly reduced to 64 +/- 8% after 2 hours. All LPS-induced changes of endothelial cells were blocked by a forskolin-mediated or rolipram-mediated increase of cAMP. Consistently, enzyme-linked immunosorbent assay-based measurements demonstrated that LPS significantly decreased intracellular cAMP. CONCLUSION In summary, our data demonstrate that LPS disrupts endothelial barrier properties by decreasing intracellular cAMP. This mechanism may involve inactivation of Rac 1 rather than activation of Rho A.
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Wang L, Dudek SM. Regulation of vascular permeability by sphingosine 1-phosphate. Microvasc Res 2009; 77:39-45. [PMID: 18973762 PMCID: PMC2693384 DOI: 10.1016/j.mvr.2008.09.005] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 09/08/2008] [Indexed: 01/11/2023]
Abstract
A significant and sustained increase in vascular permeability is a hallmark of acute inflammatory diseases such as acute lung injury (ALI) and sepsis and is an essential component of tumor metastasis, angiogenesis, and atherosclerosis. Sphingosine 1-phosphate (S1P), an endogenous bioactive lipid produced in many cell types, regulates endothelial barrier function by activation of its G-protein coupled receptor S1P(1). S1P enhances vascular barrier function through a series of profound events initiated by S1P(1) ligation with subsequent downstream activation of the Rho family of small GTPases, cytoskeletal reorganization, adherens junction and tight junction assembly, and focal adhesion formation. Furthermore, recent studies have identified transactivation of S1P(1) signaling by other barrier-enhancing agents as a common mechanism for promoting endothelial barrier function. This review summarizes the state of our current knowledge about the mechanisms through which the S1P/S1P(1) axis reduces vascular permeability, which remains an area of active investigation that will hopefully produce novel therapeutic agents in the near future.
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Affiliation(s)
- Lichun Wang
- Section of Pulmonary and Critical Care Medicine, University of Chicago Pritzker School of Medicine, Chicago, Illinois 60637, USA
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Wojciak-Stothard B, Torondel B, Zhao L, Renné T, Leiper JM. Modulation of Rac1 activity by ADMA/DDAH regulates pulmonary endothelial barrier function. Mol Biol Cell 2009; 20:33-42. [PMID: 18923147 PMCID: PMC2613095 DOI: 10.1091/mbc.e08-04-0395] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 09/29/2008] [Accepted: 10/07/2008] [Indexed: 01/05/2023] Open
Abstract
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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