title: Involvement of RhoA/Rho-associated kinase signal transduction pathway in dexamethasone-induced alterations in aqueous outflow.
abstract: OBJECTIVE
  We investigated the involvement of the RhoA/Rho kinase (ROCK) signal transduction pathway in dexamethasone (DEX)-induced changes in aqueous outflow.
  
  
  METHODS
  Using trabecular meshwork (TM) and Schlemm's canal endothelial (SCE) cells, RhoA activation was evaluated with a pull-down assay and myosin light chain phosphorylation was evaluated by Western blot analysis. Outflow facility was measured in perfused porcine anterior segment organ cultures treated with DEX and/or Y-27632, a selective ROCK inhibitor. The barrier function of the cultured cells on a micropore filter was evaluated by measuring the transendothelial electrical resistance. Collagen, fibronectin, and integrin mRNA expression levels were evaluated by quantitative real-time RT-PCR.
  
  
  RESULTS
  Relative RhoA activities increased following stimulation with 100 nM DEX in TM and SCE cells. Perfusion with DEX decreased outflow facility by 31.9 ± 14.3% compared to controls at 24 hours, but not by 50 μM Y-27632 in addition to DEX. The transendothelial electrical resistance of the SCE cell monolayer was increased by 48.6 ± 6.4% and 5.3 ± 5.0% following DEX treatments without and with 10 μM Y-27632, respectively, compared to controls. In TM cells, the mRNA expressions of COL4A1 and fibronectin were increased significantly by DEX treatment, but combined treatment with Y-27632 and DEX significantly inhibited the increase in COL4A1 and fibronectin expression.
  
  
  CONCLUSIONS
  Activation of the Rho/ROCK pathway in SCE cells contributes to the mechanism of DEX-induced changes in aqueous outflow.
authors.affiliation: Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Inoue
authors.forename: Takanori
authors.initials: T
authors.lastname: Kameda
authors.forename: Nanako
authors.initials: N
authors.lastname: Kasaoka
authors.forename: Miyuki
authors.initials: M
authors.lastname: Inoue-Mochita
authors.forename: Naoko
authors.initials: N
authors.lastname: Tsuboi
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Tanihara
mesh_terms: D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000818:Animals; D000867:Anterior Chamber / Q000378:metabolism; D001082:Aqueous Humor / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005938:Glucocorticoids / Q000494:pharmacology; D016023:Integrins / Q000235:genetics; D007365:Intercellular Junctions / Q000187:drug effects / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism; D009924:Organ Culture Techniques; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology*; D013552:Swine; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D054460:rho-Associated Kinases / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D005938:Glucocorticoids; D016023:Integrins; D018994:Myosin Light Chains; D011725:Pyridines; D012333:RNA, Messenger; C108830:Y 27632; D003907:Dexamethasone; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein