title: Role and mechanism of tissue plasminogen activator in venous wall fibrosis remodeling after deep venous thrombosis via the glycogen synthase kinase-3 beta signaling pathway.
abstract: BACKGROUND
  Deep venous thrombosis (DVT) confers vein wall injury associated with fibrosis and extracellular matrix turnover. The activation of vascular smooth muscle cells (VSMCs) and phenotypic switching are postulated to be the significant contributing factors in the evolution of the pathogenic processes. This study investigated the effect of tissue plasminogen activator (tPA) on the phenotypic switching and collagen deposition of VSMCs, as well as related signaling pathway that leads to this activation.
  
  
  METHODS
  The model of stasis-induced DVT was established by ligation of the femoral vein. VSMCs transfected with the plasmid vector carrying a rat recombinant tPA gene with an enhanced green fluorescent protein (EGFP) tag (AdtPA-EGFP). Fibrotic change, expression of collagen type I, the cell number of media, and intimal thickness score were evaluated; the comparisons were made among the AdtPA-EGFP-transfected group, an empty vector (AdNull-EGFP) transfected group, and a phosphate-buffered saline perfused group in vivo. tPA induced VSMCs phenotypic switching and collagen deposition in vitro. The related signaling pathway molecules and the cell cycle progression were also investigated by western blot and flow cytometry.
  
  
  RESULTS
  In the AdtPA-EGFP stasis DVT model, early vein wall collagenolysis and deposition occurred more remarkable. Histological studies showed that the expression of vein wall collagen type I protein, cell number of media, and intimal thickness score was significantly increased (P < 0.05). In primary culture VSMCs, sustained stimulation with tPA induced collagen type I upregulation and triggered sequential signaling events involving Akt, extracellular signal-regulated kinases 1/2 (ERK1/2), glycogen synthase kinase-3 (GSK3)-β phosphorylation, and cyclin D1 induction. Blockade of phosphatidylinositol 3-kinase-Akt and ERK1/2 activation suppressed tPA-induced GSK3β phosphorylation, cyclin D1 expression, and the deposition of collagen type I.
  
  
  CONCLUSIONS
  tPA was a profibrotic factor that potentiated the phenotypic switching and the deposition of collagen in VSMC. The effect of tPA on VSMCs involved activation of Akt and ERK1/2 pathways and inhibition of GSK3β activity, which could promote a switch of the synthetic phenotype in VSMCs and lead to the remodeling of vascular injury.
authors: Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai JiaoTong University School of Medicine, Shanghai, China; Vascular Center of Shanghai JiaoTong University, Shanghai, China.
authors: Minyi
authors: M
authors: Yin
authors: Shuo
authors: S
authors: Tian
authors: Xintian
authors: X
authors: Huang
authors: Ying
authors: Y
authors: Huang
authors: Mier
authors: M
authors: Jiang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D005268:Femoral Vein / Q000187:drug effects / Q000473:pathology*; D005355:Fibrosis; D038362:Glycogen Synthase Kinase 3 / Q000502:physiology*; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D010959:Tissue Plasminogen Activator / Q000494:pharmacology / Q000502:physiology*; D020246:Venous Thrombosis / Q000503:physiopathology*
chemical_list: D003094:Collagen; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D010959:Tissue Plasminogen Activator
keywords: Deep venous thrombosis; GSK3β; Vein wall remodeling; tPA