title: Dexamethasone increases Cdc42 expression in human TM-1 cells.
abstract: OBJECTIVE
  Changes in the cytoskeletal organization of the human trabecular meshwork (HTM) is thought to be responsible for primary open-angle glaucoma (POAG) pathologies. Cdc42 is a Rho GTPase; Rho GTPases are important modulatory agents of the cytoskeleton. This study aimed to investigate the effects of dexamethasone (DEX) on Cdc42 in a transformed HTM cell line, TM-1 to understand the molecular pathologies underlying POAG.
  
  
  METHODS
  TM-1 cells were cultured in vitro. The cultures were treated with DEX at 10(-6) and 10(-7) M for 1-4 days. Cdc42 was silenced using small interfering RNA (siRNA). The expression levels of Cdc42 in the TM-1 cells were measured using reverse transcription (RT)-PCR, western blotting analysis and immunofluorescence. Its downstream effectors, p21-activated kinase phosphorylation (phospho-PAK) and myosin light chain kinase (MLCK), were measured using western blotting analysis. In addition, the F-actin of TM-1 cells was stained using phalloidin.
  
  
  RESULTS
  The mRNA and protein levels of Cdc42 showed an increase in TM-1 cells with DEX treatment and a decrease in TM-1 cells transfected with Cdc42 siRNA. Moreover, phospho-PAK levels increased, whereas MLCK levels appeared to decrease, with DEX treatment. The F-actin of DEX-treated TM-1 cells displayed a rearrangement. Cdc42 siRNA decreased the expression of Cdc42 and its related proteins, resulting in an attenuation of the effects of DEX on Cdc42 and F-actin organization in TM-1 cells.
  
  
  CONCLUSIONS
  DEX increases Cdc42 expression in TM-1. This may represent a potential mechanism of DEX-induced HTM cytoskeletal rearrangement.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University , Guangzhou , China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Qiu
authors.forename: Kaili
authors.initials: K
authors.lastname: Wu
authors.forename: Xianchai
authors.initials: X
authors.lastname: Lin
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Yiming
authors.initials: Y
authors.lastname: Ye
authors.forename: Minbin
authors.initials: M
authors.lastname: Yu
mesh_terms: D000199:Actins / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D002461:Cell Line, Transformed; D002470:Cell Survival; D003907:Dexamethasone / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D020868:Gene Silencing; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014129:Trabecular Meshwork / Q000187:drug effects* / Q000378:metabolism; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D005938:Glucocorticoids; D034741:RNA, Small Interfering; D003907:Dexamethasone; D020764:cdc42 GTP-Binding Protein
keywords: Cdc42; Dexamethasone; F-actin; human trabecular meshwork cells