title: [The mechanism of transforming growth factor beta1 in myofibroblast differentiation].
abstract: OBJECTIVE
  To investigate the mechanism underlying myofibroblast differentiation induced by transforming growth factor (TGF) beta1 in obliterative bronchiolitis following lung transplantation.
  
  
  METHODS
  Heterotopic tracheal transplantation was performed in Smad3 wild-type and knock-out mice to simulate the lung transplantation in human. Murine tracheal fibroblasts cultivated in primary culture were used for in vitro study. Immunohistochemistry, immunocytochemistry, Western Blotting, RT-PCR and DNA electrophoresis mobility gel shift assay were conducted to detect the expression of alpha-smooth muscle actin (alphaSMA), the marker of fibroblast-myofibroblast differentiation, and the activation of Smad3, p38 and ERK1/2.
  
  
  RESULTS
  In affected airways of experimental obliterative bronchiolitis, abundant expression of alphaSMA were found. In vitro study for tracheal fibroblasts, the activation of Smad3 by TGF-beta1 presents as three major forms, phosphorylation, nuclear translocation and DNA binding. In Smad3 wild-type fibroblasts, TGF-beta1 induces the increase of the myofibroblasts transformation, characterized by the elevation of alphaSMA, both at transcription and protein level. While in Smad3 knock-out fibroblasts, the transformation of myofibroblasts induced by TGF-beta1 is significantly decreased (t = 2.080, P = 0.027; t = 1.982, P = 0.032), but not completely abolished. Further study in Smad3-deficient fibroblasts demonstrates that p38 and ERK1/2 could be activated by TGF-beta1 and result in fibroblast differentiation.
  
  
  CONCLUSIONS
  TGF-beta1 could promote the transformation of fibroblasts into myofibroblasts in Smad3 dependent and independent signal pathways, especially the Smad3 dependent path, and result in the development of obliterative bronchiolitis.
authors.affiliation: Department of Thoracic Surgery, First Hospital, China Medical University, Shenyang 110001, China. hongxuliu@yahoo.com
authors.forename: Hong-xu
authors.initials: HX
authors.lastname: Liu
authors.forename: Si-wen
authors.initials: SW
authors.lastname: Wang
authors.forename: Cheng-hai
authors.initials: CH
authors.lastname: Zhao
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.forename: Qi-gang
authors.initials: QG
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Cong
authors.forename: Xin-gang
authors.initials: XG
authors.lastname: Lan
authors.forename: Shun
authors.initials: S
authors.lastname: Xu
authors.forename: Li-bo
authors.initials: LB
authors.lastname: Han
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D001989:Bronchiolitis Obliterans / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000637:transplantation; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000199:Actins; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases