title: Differential effects of shear stress and cyclic stretch on focal adhesion remodeling, site-specific FAK phosphorylation, and small GTPases in human lung endothelial cells.
abstract: Regulation of endothelial cell (EC) permeability by bioactive molecules is associated with specific patterns of cytoskeletal and cell contact remodeling. A role for mechanical factors such as shear stress (SS) and cyclic stretch (CS) in cytoskeletal rearrangements and regulation of EC permeability becomes increasingly recognized. This paper examined redistribution of focal adhesion (FA) proteins, site-specific focal adhesion kinase (FAK) phosphorylation, small GTPase activation and barrier regulation in human pulmonary EC exposed to laminar shear stress (15 dyn/cm2) or cyclic stretch (18% elongation) in vitro. SS caused peripheral accumulation of FAs, whereas CS induced randomly distributed FAs attached to the ends of newly formed stress fibers. SS activated small GTPase Rac without effects on Rho, whereas 18% CS activated without effect on Rac. SS increased transendothelial electrical resistance (TER) in EC monolayers, which was further elevated by barrier-protective phospholipid sphingosine 1-phosphate. Finally, SS induced FAK phosphorylation at Y576, whereas CS induced FAK phosphorylation at Y397 and Y576. These results demonstrate for the first time differential effects of SS and CS on Rho and Rac activation, FA redistribution, site-specific FAK phosphorylation, and link them with SS-mediated barrier enhancement. Thus, our results suggest common signaling and cytoskeletal mechanisms shared by mechanical and chemical factors involved in EC barrier regulation.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, School of Medicine, 5200 Eastern Avenue, Mason F. Lord Building, Center Tower, Room 677, Baltimore, MD 21224, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shikata
authors.forename: Alexander
authors.initials: A
authors.lastname: Rios
authors.forename: Kamon
authors.initials: K
authors.lastname: Kawkitinarong
authors.forename: Natacha
authors.initials: N
authors.lastname: DePaola
authors.forename: Joe G N
authors.initials: JG
authors.lastname: Garcia
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Birukov
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins / Q000032:analysis; D003598:Cytoskeletal Proteins / Q000032:analysis; D004548:Elasticity; D042783:Endothelial Cells / Q000737:chemistry / Q000201:enzymology / Q000648:ultrastructure; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions / Q000201:enzymology* / Q000648:ultrastructure; D020690:GTPase-Activating Proteins / Q000032:analysis; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000201:enzymology*; D051419:Paxillin; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013314:Stress, Mechanical; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C485647:GIT1 protein, human; C430213:GIT2 protein, human; D020690:GTPase-Activating Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins