title: [Effect of tensile stress on fibronectin-integrins-cytoskeleton in cultured human periodontal ligament fibroblasts].
abstract: OBJECTIVE
  To investigate the effect of different dynamic tensile stress on the expression of fibronectin, integrins β1 subunit and cytoskeleton in cultured human periodontal ligament fibroblasts(hPDLF).
  
  
  METHODS
  The periodontal ligament attached to the mid-third part of fresh root of young premolars extracted for orthodontics was scalped and removed. hPDLF was cultured by the method of digesting by I-type collagenase combining with tissue adhering. Then hPDLF was isolated and purified by cells passage. The cells were planted on plates in a density of 2.0±10(5)/plate before loading. "Forcel" four point bending device was used for mechanical loading. Cells were loaded by three levels (1000μstrain, 2000μstrain, 4000μstrain) of tensile stress and collected at different time(0h,0.5h,1h,4h,8h,12h) after strain loading. The quantity of mRNA of fibronectin and integrins β1 subunit in each group was analyzed by means of quantitative real-time PCR with the special primers of up- and down-regulated genes. The morphological change of cytoskeleton was observed by fluorescence converted microscope at different time after loading tensile stress. The data was analyzed by ANOVA with SPSS 13.0 software package.
  
  
  RESULTS
  Tensile stress of different magnitude and different time significantly changed the mRNA expression of fibronectin in hPDLF.Dynamic tensile stress down-regulated the mRNA expression of integrins β1 subunit in hPDLF and the difference in groups by different magnitude and different time of mechanical forces loading was statistically significant. The stronger stimulated forces,the more down-regulated expression. The change of morphological characteristics of cyto- skeleton was statistically significant among all the groups. After loading,the shape of cells became irregular, cell arranged along the direction of loaded forces, microfilament became thinner and arranged unevenly.As the effect of mechanical force became longer,the above change vanished.
  
  
  CONCLUSIONS
  Dynamic tensile stress could regulate the expression of mRNA fibronectin and integrins β1 subunit, and could also change the morphological characteristics of cytoskeleton. Supported by National Natural Science Foundation of China(Grant No.30700959) and Research Fund of Medical and Health Science of Zhejiang Province(Grant No.2008A113).
authors: Department of Prosthodontics, Affiliated Stomatological Hospital, Medical College, Zhejiang University. Hangzhou 310006,Zhejiang Province, China. zqdwjh@163.com
authors: Qing-Dang
authors: QD
authors: Zhu
authors: Li
authors: L
authors: Liu
authors: Yan-Li
authors: YL
authors: Yang
mesh_terms: D001641:Bicuspid; D002478:Cells, Cultured; D003599:Cytoskeleton; D005347:Fibroblasts; D005353:Fibronectins; D006801:Humans; D016023:Integrins; D010513:Periodontal Ligament; D012333:RNA, Messenger; D013314:Stress, Mechanical
chemical_list: D005353:Fibronectins; D016023:Integrins; D012333:RNA, Messenger