title: S1P induces FA remodeling in human pulmonary endothelial cells: role of Rac, GIT1, FAK, and paxillin.
abstract: Sphingosine 1-phosphate (S1P) enhances human pulmonary endothelial monolayer integrity via Rac GTPase-dependent formation of a cortical actin ring (Garcia et al. J Clin Invest 108: 689-701, 2001). The mechanisms underlying this response are not well understood but may involve rapid redistribution of focal adhesions (FA) as attachment sites for actin filaments. We evaluate the effects of S1P on the redistribution of paxillin, FA kinase (FAK), and the G protein-coupled receptor kinase-interacting proteins (GITs). S1P induced Rac GTPase activation and cortical actin ring formation at physiological concentrations (0.5 microM), whereas 5 microM S1P caused prominent stress fiber formation and activation of Rho and Rac GTPases. S1P (0.5 microM) stimulated the tyrosine phosphorylation of FAK Y(576), and paxillin was linked to FA disruption and redistribution to the cell periphery. Furthermore, S1P induced a transient association of GIT1 with paxillin and redistribution of the GIT2-paxillin complex to the cell cortical area without affecting GIT2-paxillin association. These results suggest a role of FA rearrangement in S1P-mediated barrier enhancement via Rac- and GIT-mediated processes.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shikata
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Birukov
authors.forename: Joe G N
authors.initials: JG
authors.lastname: Garcia
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions / Q000187:drug effects*; D020690:GTPase-Activating Proteins / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000187:drug effects; D008246:Lysophospholipids; D008856:Microscopy, Fluorescence; D051419:Paxillin; D010750:Phosphoproteins / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D020830:rac1 GTP-Binding Protein / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C485647:GIT1 protein, human; D020690:GTPase-Activating Proteins; D008246:Lysophospholipids; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; C060506:sphingosine 1-phosphate; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D013110:Sphingosine