title: RhoE regulates actin cytoskeleton organization in human periodontal ligament cells under mechanical stress.
abstract: OBJECTIVE
  RhoE and regulator of G-proteins signalling (RGS) 2 were identified as the up-regulated genes in human periodontal ligament (PDL) cells under compression. RhoE belongs to the Rho GTPase family, and RGS2, a novel family of GTPase-activating proteins, turns off the G-protein signalling. Rho family proteins have recently been known to regulate actin cytoskeleton dynamics in various cell types. In this study, we investigated the involvement of RhoE and RGS2 in the regulation of actin filament organization in the PDL cells under mechanical stress.
  
  
  METHODS
  Human PDL cells were cultured and subjected to a static compressive force (3.0g/cm(2)) for 48h. To observe changes in the actin cytoskeleton and the expression of RhoE and RGS2 in response to mechanical stress, immunofluorescence analysis was performed. To examine the role of RhoE and RGS2 in actin filament organization, cells were transfected with antisense S-oligonucleotides (ODNs) to RhoE and RGS2.
  
  
  RESULTS
  Compressive force caused a loss and disassembly of actin stress fibres leading to cell spreading. Immunocytochemical study revealed that RhoE and RGS2 expressions were induced by mechanical stress and localized in the perinuclear and in the cell membrane, respectively. The impaired formation of stress fibres caused by compressive forces was recovered by treatment with antisense S-ODN to RhoE to the control levels. However, addition of antisense S-ODN to RGS2 did not affect the stress fibre formation.
  
  
  CONCLUSIONS
  These results indicate that the loss and disassembly of stress fibres due to mechanical stress are mediating RhoE signalling, without the exertion of RGS2.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan.
authors.forename: Rui Mauricio Santos
authors.initials: RM
authors.lastname: de Araujo
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Oba
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kuroda
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8504, Japan. Electronic address: etanaka@tokushima-u.ac.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.affiliation: Department of Maxillofacial Orthognathics, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Moriyama
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000199:Actins / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D006801:Humans; D008856:Microscopy, Fluorescence; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010513:Periodontal Ligament / Q000166:cytology* / Q000187:drug effects; D015398:Signal Transduction; D013314:Stress, Mechanical; D014162:Transfection; D015854:Up-Regulation; D020741:rho GTP-Binding Proteins / Q000502:physiology*
chemical_list: D000199:Actins; D016376:Oligonucleotides, Antisense; D020741:rho GTP-Binding Proteins
keywords: Mechanical stress; Periodontal ligament cells; RhoE