title: Junctional complex and focal adhesion rearrangement mediates pulmonary endothelial barrier enhancement by FTY720 S-phosphonate.
abstract: BACKGROUND
  Modulation of pulmonary vascular barrier function is an important clinical goal given the devastating effects of vascular leak in acute lung injury (ALI). We previously demonstrated that FTY720 S-phosphonate (Tys), an analog of sphingosine 1-phosphate (S1P) and FTY720, has more potent pulmonary barrier protective effects than these agents in vitro and in mouse models of ALI. Tys preserves expression of the barrier-promoting S1P1 receptor (S1PR1), whereas S1P and FTY720 induce its ubiquitination and degradation. Here we further characterize the novel barrier promoting effects of Tys in cultured human pulmonary endothelial cells (EC).
  
  
  RESULTS
  In human lung EC, Tys significantly increased peripheral redistribution of adherens junction proteins VE-cadherin and β-catenin and tight junction protein ZO-1. Inhibition of VE-cadherin with blocking antibody significantly attenuated Tys-induced transendothelial resistance (TER) elevation, while ZO-1 siRNA partially inhibited this elevation. Tys significantly increased focal adhesion formation and phosphorylation of focal adhesion kinase (FAK). Pharmacologic inhibition of FAK significantly attenuated Tys-induced TER elevation. Tys significantly increased phosphorylation and peripheral redistribution of the actin-binding protein, cortactin, while cortactin siRNA partially attenuated Tys-induced TER elevation. Although Tys significantly increased phosphorylation of Akt and GSK3β, neither PI3 kinase nor GSK3β inhibition altered Tys-induced TER elevation. Tys significantly increased Rac1 activity, while inhibition of Rac1 activity significantly attenuated Tys-induced VE-cadherin redistribution and TER elevation.
  
  
  CONCLUSIONS
  Junctional complex, focal adhesion rearrangement and Rac1 activation play critical roles in Tys-mediated barrier protection in pulmonary EC. These results provide mechanistic insights into the effects of this potential ALI therapy.
authors: Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
authors: Lichun
authors: L
authors: Wang
authors: Department of Chemistry and Biochemistry, Queens College of The City University of New York, Flushing, New York, USA.
authors: Robert
authors: R
authors: Bittman
authors: Department of Medicine, University of Arizona, Tucson, AZ, USA.
authors: Joe G N
authors: JG
authors: Garcia
authors: Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA. Electronic address: sdudek@uic.edu.
authors: Steven M
authors: SM
authors: Dudek
mesh_terms: D055371:Acute Lung Injury / Q000188:drug therapy / Q000473:pathology; D015703:Antigens, CD / Q000378:metabolism; D034961:Antigens, Nuclear / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects*; D000068876:Fingolimod Hydrochloride / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D008246:Lysophospholipids / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000378:metabolism; D063065:Organophosphonates / Q000627:therapeutic use*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000737:chemistry; D014157:Transcription Factors / Q000378:metabolism; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000099152:Cadherin 5; D000092468:Bromodomain Containing Proteins
chemical_list: D015703:Antigens, CD; D034961:Antigens, Nuclear; D015820:Cadherins; D000068876:Fingolimod Hydrochloride; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007166:Immunosuppressive Agents; D008246:Lysophospholipids; D009419:Nerve Tissue Proteins; D063065:Organophosphonates; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D013110:Sphingosine; D014157:Transcription Factors; D062826:Zonula Occludens-1 Protein; D020830:rac1 GTP-Binding Protein; D000099152:Cadherin 5; C000606732:2-amino-2-(2-(4-octylphenyl)ethyl)propane-1,3-diol phosphonate; C107953:RAC1 protein, human; C569042:TJP1 protein, human; C406238:fetal Alzheimer antigen; D000092468:Bromodomain Containing Proteins; C060506:sphingosine 1-phosphate
keywords: Acute lung injury; FTY720 S-phosphonate; Pulmonary vascular barrier; Rac1; VE-cadherin