title: TGF beta-induced contraction is not promoted by fibronectin-fibronectin receptor interaction, or alpha SMA expression.
abstract: OBJECTIVE
  Transforming growth factor (TGF)-beta is a potent inducer of both transdifferentiation and contraction, which are regarded as critical processes that underpin tissue fibrosis. Consequently, transdifferentiation is believed to drive TGFbeta-mediated contraction. This study was conducted to determine the relationship between transdifferentiation of human lens epithelial cells and matrix contraction.
  
  
  METHODS
  Real-time PCR was used to investigate gene expression of transdifferentiation markers in the human lens cell line FHL 124 and native lens epithelia. Contraction was assessed with a patch-contraction assay, whereby all areas covered by cells were measured with imaging techniques after fixation and cell staining with Coomassie blue. In addition, total protein content, determined by dye extractions was used to give an estimate of total cell population. To prevent fibronectin-fibronectin receptor interaction 100 microM RGDS peptide was used. Suppression of TGFbeta-induced alphaSMA expression was mediated by siRNA technology.
  
  
  RESULTS
  Real-time PCR analysis showed 10 ng/mL TGF-beta1 or -beta2 significantly increased expression of alphaSMA, fibronectin, and alpha5beta1 integrin (fibronectin receptor components) in FHL 124 cells and human lens epithelia. Cultures maintained in TGFbeta and RGDS showed a marked increase in the rate of contraction relative to TGF-beta alone. RGDS alone did not differ significantly from the control. Real-time PCR and Western blots showed reduced levels of message and alphaSMA protein when transfected with siRNA. alphaSMA knockdown did not prevent TGFbeta-induced contraction.
  
  
  CONCLUSIONS
  A targeted inhibition approach demonstrated that key elements associated with transdifferentiation are not critical for TGFbeta-induced matrix contraction.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich, UK.
authors.forename: Lucy Jean
authors.initials: LJ
authors.lastname: Dawes
authors.forename: Julie Ann
authors.initials: JA
authors.lastname: Eldred
authors.forename: Ian Kevin
authors.initials: IK
authors.lastname: Anderson
authors.forename: Matthew
authors.initials: M
authors.lastname: Sleeman
authors.forename: John R
authors.initials: JR
authors.lastname: Reddan
authors.forename: George
authors.initials: G
authors.lastname: Duncan
authors.forename: Ian Michael
authors.initials: IM
authors.lastname: Wormstone
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D054338:Cell Transdifferentiation / Q000187:drug effects*; D003286:Contracture; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D039081:Integrin alpha5beta1 / Q000235:genetics / Q000378:metabolism*; D007908:Lens, Crystalline / Q000166:cytology*; D009842:Oligopeptides / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D000199:Actins; D005353:Fibronectins; D039081:Integrin alpha5beta1; D009842:Oligopeptides; D034741:RNA, Small Interfering; D016212:Transforming Growth Factor beta; C046617:arginyl-glycyl-aspartyl-serine