title: Lung endothelial barrier disruption in Lyl1-deficient mice.
abstract: Maturation of newly formed vessels is a multistep phenomenon during which functional endothelial barriers are established. Disruption of vessel integrity is an important feature in many physiological and pathological processes. We previously reported that lymphoblastic leukemia-derived sequence 1 (LYL1) is required for the late stages of postnatal angiogenesis to limit the formation of new blood vessels, notably by regulating the activity of the small GTPase Rap1. In this study, we show that LYL1 is also required during the formation of the mature endothelial barrier in the lungs of adult mice. Specifically, LYL1 knockdown in human endothelial cells downregulated the expression of ARHGAP21 and ARHGAP24, which encode two Rho GTPase-activating proteins, and this was correlated with increased RhoA activity and reorganization of the actin cytoskeleton into stress fibers. Importantly, in lungs of Lyl1-deficient mice, both vascular endothelial (VE)-cadherin and p120-catenin were poorly recruited to endothelial adherens junctions, indicative of defective cell-cell junctions. Consistent with this, higher Evans blue dye extravasation, edema, and leukocyte infiltration in the lung parenchyma of Lyl1-/- mice than in wild-type littermates confirmed that lung vascular permeability is constitutively elevated in Lyl1-/- adult mice. Our data show that LYL1 acts as a stabilizing signal for adherens junction formation by operating upstream of VE-cadherin and of the two GTPases Rap1 and RhoA. As increased vascular permeability is a key feature and a major mechanism of acute respiratory distress syndrome, molecules that regulate LYL1 activity could represent additional tools to modify the endothelial barrier permeability.
authors: Institut de Génétique Moléculaire de Montpellier, UMR 5535, CNRS, 1919 route de Mende, 34293 Montpellier cedex 5, France. valerie.pinet@igmm.cnrs.fr.
authors: Nelly
authors: N
authors: Pirot
authors: Hélène
authors: H
authors: Delpech
authors: Virginie
authors: V
authors: Deleuze
authors: Christiane
authors: C
authors: Dohet
authors: Monique
authors: M
authors: Courtade-Saïdi
authors: Céline
authors: C
authors: Basset-Léobon
authors: Elias
authors: E
authors: Chalhoub
authors: Danièle
authors: D
authors: Mathieu
authors: Valérie
authors: V
authors: Pinet
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D015153:Blotting, Western; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D008168:Lung / Q000098:blood supply / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009363:Neoplasm Proteins / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D022502:Stress Fibers; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D051792:Basic Helix-Loop-Helix Proteins; D020690:GTPase-Activating Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D020827:rap1 GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C497034:ARHGAP24 protein, mouse; C490130:Lyl1 protein, mouse
keywords: RhoA; bHLH; lymphoblastic leukemia-derived sequence 1; vascular endothelial-cadherin; vascular permeability