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.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/physiology , Cell Membrane Permeability , Endothelium, Vascular/pathology , Human Umbilical Vein Endothelial Cells/pathology , Lung/pathology , Neoplasm Proteins/physiology , Actins/genetics , Actins/metabolism , Animals , Blotting, Western , Cells, Cultured , Endothelium, Vascular/metabolism , Fluorescent Antibody Technique , GTPase-Activating Proteins/genetics , GTPase-Activating Proteins/metabolism , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Immunoenzyme Techniques , Lung/blood supply , Lung/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Stress Fibers , rap1 GTP-Binding Proteins/genetics , rap1 GTP-Binding Proteins/metabolism , rhoA GTP-Binding Protein/genetics , rhoA GTP-Binding Protein/metabolismABSTRACT
OBJECTIVE: To report the clinical and neuropathological features in the first patient seen, to our knowledge, with familial Creutzfeldt-Jakob disease and an R208H mutation associated with a Val/Val homozygosity at codon 129 in the prion protein gene (PRNP) and a type 2 protease-resistant prion protein. PATIENT AND RESULTS: A 61-year-old man with a long-standing history of memory loss and emotional disorders had an obvious behavioral change. Then he developed cerebellar ataxia, followed by cognitive decline. He had no myoclonus. Electroencephalography showed slow activity, and 14-3-3 protein detection was negative. Finally, the patient developed akinetic mutism and died 7 months after the onset of ataxia. Neuropathological examination showed severe spongiform changes in the frontal cortex and striatum and gliosis in the striatum and thalamus. Kuru plaques were noted in the cerebellum, notably in the molecular layer. Immunohistochemical findings showed granular, synaptic, perineuronal, and perivacuolar staining with antiprion antibodies. Kuru plaques were also stained. CONCLUSION: This study strengthens the linkage of the R208H mutation to Creutzfeldt-Jakob disease and points to some particular features such as Kuru plaques and long-standing psychiatric signs.
