title: Endothelial barrier strengthening by activation of focal adhesion kinase.
abstract: Endothelial cell barrier (EC) properties regulate blood tissue fluid flux. To determine the role of endothelial-matrix interactions in barrier regulation, we induced cell shrinkage by exposing confluent endothelial monolayers to hyperosmolarity. The dominant effect of a 15-min hyperosmolar exposure was an increase in the trans-endothelial electrical resistance, indicating the induction of barrier strengthening. Hyperosmolar exposure also increased activity of focal adhesion kinase and E-cadherin accumulation at the cell periphery. Concomitantly, the density of actin filaments increased markedly. In EC monolayers stably expressing constitutively active or dominant negative isoforms of Rac1, the actin response to hyperosmolar exposure was enhanced or blocked, respectively, although the response in trans-endothelial resistance was unaffected, indicating that the endothelial barrier enhancement occurred independently of actin. However, in monolayers expressing a kinase-deficient mutant of focal adhesion kinase, the hyperosmolarity-induced increases in activity of focal adhesion and peripheral E-cadherin enhancement were blocked and the induced increase of electrical resistance was markedly blunted. These findings indicate that in EC exposed to hyperosmolar challenge, the involvement of focal adhesion kinase was critical in establishing barrier strengthening.
authors.affiliation: Lung Biology Laboratory, College of Physicians and Surgeons, Columbia University, St. Luke's-Roosevelt Hospital Center, New York, New York 10019, USA.
authors.forename: Sadiqa K
authors.initials: SK
authors.lastname: Quadri
authors.forename: Mrinal
authors.initials: M
authors.lastname: Bhattacharjee
authors.forename: Kaushik
authors.initials: K
authors.lastname: Parthasarathi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Tanita
authors.forename: Jahar
authors.initials: J
authors.lastname: Bhattacharya
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000502:physiology*; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007700:Kinetics; D008168:Lung; D008833:Microcirculation; D009994:Osmolar Concentration; D010957:Plasmids; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011652:Pulmonary Circulation; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D011994:Recombinant Proteins; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat