title: Guanine nucleotide exchange factor-H1 signaling is involved in lipopolysaccharide-induced endothelial barrier dysfunction.
abstract: BACKGROUND
  Gram-negative bacterial lipopolysaccharide (LPS) leads to the pathologic increase of vascular leakage under septic conditions. However, the mechanisms behind LPS-induced vascular hyperpermeability remain incompletely understood. In this study, we tested hypothesis that guanine nucleotide exchange factor-H1 (GEF-H1) signaling might be a key pathway involved in endothelial cells (ECs) barrier dysfunction.
  
  
  METHODS
  The roles of GEF-H1 signaling pathway in LPS-induced ECs barrier dysfunction were accessed by Evans blue dye-labeled albumin (EB-albumin) leak across the human umbilical vein EC (HUVEC) monolayers and Western blot assays. Furthermore, the effect of GEF-H1 signaling on LPS-induced alteration of cytoskeletal proteins and disruption of cell-cell junctions were analyzed by immunofluorescent analysis and Western blot assays, respectively.
  
  
  RESULTS
  We found that LPS could rapidly activated GEF-H1/RhoA/Rho-associated protein kinase (ROCK) signaling pathway in ECs. The LPS-mediated increase in EB-albumin flux across human HUVECs monolayers could be prevented by GEF-H1 depletion or ROCK inactivation. ECs permeability is controlled by actin filaments and cell-cell contact protein complexes. Actin stress fiber formation and/or cell-cell contact proteins loss cause vascular barrier disruption. Here, GEF-H1 knockdown or ROCK inactivation both not only significantly inhibited LPS-induced actin stress fiber formation, phosphorylation of myosin light chain, and myosin-associated phosphatase type 1, but also suppressed LPS-induced loss of occludin, claudin-1, and vascular endothelial (VE)-cadherin in ECs, which suggested that LPS-induced stress fiber formation and cell-cell junctions disruption were closely associated with GEF-H1/RhoA/ROCK signaling activation.
  
  
  CONCLUSIONS
  Our findings indicate that GEF-H1/RhoA/ROCK pathway in ECs plays an important role in LPS-mediated alteration of cell morphology and disruption of cell-cell junctions, consequently regulate LPS-induced vascular permeability dysfunction.
authors.affiliation: Department of Burn and Plastic Surgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zengding
authors.initials: Z
authors.lastname: Zhou
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Yi
authors.initials: Y
authors.lastname: Dou
authors.forename: Jiajun
authors.initials: J
authors.lastname: Tang
authors.forename: Jingning
authors.initials: J
authors.lastname: Huan
mesh_terms: D002199:Capillary Permeability / Q000187:drug effects*; D003599:Cytoskeleton / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D006801:Humans; D007365:Intercellular Junctions / Q000187:drug effects; D008070:Lipopolysaccharides / Q000633:toxicity*; D064067:Rho Guanine Nucleotide Exchange Factors; D054460:rho-Associated Kinases / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000502:physiology
chemical_list: C577356:ARHGEF2 protein, human; D020662:Guanine Nucleotide Exchange Factors; D008070:Lipopolysaccharides; D064067:Rho Guanine Nucleotide Exchange Factors; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein