Dasatinib inhibits actin fiber reorganization and promotes endothelial cell permeability through RhoA-ROCK pathway.

Treatment with dasatinib, a tyrosine kinase inhibitor, is associated with edema, pleural effusion, and pulmonary edema. We investigated the effect of dasatinib on the barrier function of human microvascular endothelial cells-1 (HMEC-1) in vitro and in vivo. The permeability of HMEC-1 to fluorescein isothiocyante (FITC)-dextran increased in Transwell chambers within 5 min following the addition of therapeutic concentrations of dasatinib.

Wdr1-Dependent Actin Reorganization in Platelet Activation.

In resting platelets, the integrin αIIbβ3 is present in a low-affinity "bent" state. During platelet aggregation, intracytoplasmic signals induce conformational changes (inside-out signaling) that result in a "swung-out" conformation competent to bind ligands such as fibrinogen. The cytoskeleton plays an essential role in αIIbβ3 activation.

Rho associated coiled-coil kinase-1 regulates collagen-induced phosphatidylserine exposure in platelets.

Background: The transbilayer movement of phosphatidylserine mediates the platelet procoagulant activity during collagen stimulation. The Rho-associated coiled-coil kinase (ROCK) inhibitor Y-27632 inhibits senescence induced but not activation induced phosphatidylserine exposure. To investigate further the specific mechanisms, we now utilized mice with genetic deletion of the ROCK1 isoform.

Developmental endothelial locus-1 (Del-1) mediates clearance of platelet microparticles by the endothelium.

Background: Phosphatidylserine-expressing microparticles circulate in blood with a short half-life of <10 minutes. We tested the role of an endothelium-derived phosphatidylserine-binding opsonin, developmental endothelial locus-1 (Del-1), in the uptake of platelet microparticles.

Methods And Results: Cultured human umbilical vein and microvascular endothelial cells avidly engulf BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-maleimide-labeled platelet microparticles.

Phagocytosis of platelet microvesicles and beta2- glycoprotein I.

The majority of the antiphospholipid antibodies, present in patients with antiphospholipid syndrome, are directed against conformational epitopes in beta2-glycoprotein I. beta2-glycoprotein I is an anionic phospholipid-binding 50-kDa plasma protein whose physiological role is not clear. Here we investigate the role of beta2-glycoprotein I in the phagocytosis of phosphatidylserine-expressing platelet microvesicles and the effect of autoantibodies to beta2-glycoprotein I on this process.

Lactadherin and clearance of platelet-derived microvesicles.

The transbilayer movement of phosphatidylserine from the inner to the outer leaflet of the membrane bilayer during platelet activation is associated with the release of procoagulant phosphatidylserine-rich small membrane vesicles called platelet-derived microvesicles. We tested the effect of lactadherin, which promotes the phagocytosis of phosphatidylserine-expressing lymphocytes and red blood cells, in the clearance of platelet microvesicles. Platelet-derived microvesicles were labeled with BODIPY-maleimide and incubated with THP-1-derived macrophages.

Lactadherin mediates sickle cell adhesion to vascular endothelial cells in flowing blood.

Increased exposure of sickle red blood cells to phosphatidylserine promotes its adhesion to the endothelium. A monoclonal antibody to lactadherin, a phosphatidylserine binding protein, inhibits sickle cell adhesion to histamine-stimulated endothelial cells in flowing blood. Added lactadherin enhances the adhesion via the integrin alphaVbeta3.

Lupus-derived antiprothrombin autoantibodies from a V gene phage display library are specific for the kringle 2 domain of prothrombin.

Autoantibodies to prothrombin are common in patients with systemic lupus erythematosus. Although their presence is a risk factor for thrombosis, neither their origin nor their precise role in inducing the procoagulant state is known. We have developed a phage-display antibody library from patients with systemic lupus erythematosus with antiprothrombin antibodies, and we have selected two single-chain Fv antibody fragments (ScFvs) by panning on a prothrombin-coated surface.