title: The effect of centrifugal force on mRNA levels of collagenase, collagen type-I, tissue inhibitors of metalloproteinases and beta-actin in cultured human periodontal ligament fibroblasts.
abstract: BACKGROUND
  The aim of orthodontic treatment is to relocate teeth abnormally positioned in the jaws. This is achieved by application of continuous force on the tooth, which is immediately being sensed by the periodontal ligament (PDL), bone and the gingiva. Since the bony response is mediated by the PDL, tooth movement is primarily a PDL phenomenon.
  
  
  OBJECTIVE
  Thus, the purpose of the present study was to evaluate the direct effect of force (excluding the in vivo tissue response) on the molecular level of matrix metalloproteinase-1 (MMP-1) and collagen type-I (Col-I) in human PDL fibroblasts.
  
  
  METHODS
  PDL cell culture flasks were centrifuged for 10, 20, 30, 60, 90 and 120 min by horizontal microplate rotor. The effect of force on mRNA levels of beta-actin, MMP-1, Col-I, tissue inhibitors-1 and -2 (TIMPs) genes was analyzed by RT-PCR.
  
  
  RESULTS
  The results showed that force had no effect on the mRNA levels of beta-actin during the first 90 min of application of force, indicating for the first time the use of beta-actin gene as an internal invariant control. It increased the mRNA levels of MMP-1 while almost no effect on Col-I and TIMPs was observed.
  
  
  CONCLUSIONS
  The results indicate that PDL remodeling following application of orthodontic force could be partly attributed to the direct effect of the force on MMP-1 gene expression in fibroblasts.
authors.affiliation: Department of Orthodontics, Hebrew University--Hadassah Faculty of Dental Medicine, founded by the Alpha Omega Fraternity, Jerusalem 91220, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Redlich
authors.forename: H
authors.initials: H
authors.lastname: Roos
authors.forename: E
authors.initials: E
authors.lastname: Reichenberg
authors.forename: B
authors.initials: B
authors.lastname: Zaks
authors.forename: A
authors.initials: A
authors.lastname: Grosskop
authors.forename: I
authors.initials: I
authors.lastname: Bar Kana
authors.forename: S
authors.initials: S
authors.lastname: Pitaru
authors.forename: A
authors.initials: A
authors.lastname: Palmon
mesh_terms: D000199:Actins / Q000032:analysis*; D002478:Cells, Cultured; D002498:Centrifugation; D024042:Collagen Type I / Q000032:analysis* / Q000235:genetics; D017364:Collagenases / Q000032:analysis* / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D020781:Matrix Metalloproteinase 1 / Q000032:analysis; D010513:Periodontal Ligament / Q000378:metabolism*; D011480:Protease Inhibitors / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis*; D013314:Stress, Mechanical; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000032:analysis; D019714:Tissue Inhibitor of Metalloproteinases / Q000032:analysis* / Q000235:genetics
chemical_list: D000199:Actins; D024042:Collagen Type I; D011480:Protease Inhibitors; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D019714:Tissue Inhibitor of Metalloproteinases; D019716:Tissue Inhibitor of Metalloproteinase-2; D017364:Collagenases; D020781:Matrix Metalloproteinase 1