title: BMP-2 up-regulates PTEN expression and induces apoptosis of pulmonary artery smooth muscle cells under hypoxia.
abstract: OBJECTIVE
  To investigate the role of bone morphogenetic protein 2 (BMP-2) in regulation of phosphatase and tensin homologue deleted on chromosome ten (PTEN) and apoptosis of pulmonary artery smooth muscle cells (PASMCs) under hypoxia.
  
  
  METHODS
  Normal human PASMCs were cultured in growth medium (GM) and treated with BMP-2 from 5-80 ng/ml under hypoxia (5% CO(2)+94% N(2)+1% O(2)) for 72 hours. Gene expression of PTEN, AKT-1 and AKT-2 were determined by quantitative RT-PCR (QRT-PCR). Protein expression levels of PTEN, AKT and phosph-AKT (pAKT) were determined. Apoptosis of PASMCs were determined by measuring activities of caspases-3, -8 and -9. siRNA-smad-4, bpV(HOpic) (PTEN inhibitor) and GW9662 (PPARγ antagonist) were used to determine the signalling pathways.
  
  
  RESULTS
  Proliferation of PASMCs showed dose dependence of BMP-2, the lowest proliferation rate was achieved at 60 ng/ml concentration under hypoxia (82.2±2.8%). BMP-2 increased PTEN gene expression level, while AKT-1 and AKT-2 did not change. Consistently, the PTEN protein expression also showed dose dependence of BMP-2. AKT activity significantly reduced in BMP-2 treated PASMCs. Increased activities of caspase-3, -8 and -9 of PASMCs were found after cultured with BMP-2. PTEN expression remained unchanged when Smad-4 expression was inhibited by siRNA-Smad-4. bpV(HOpic) and GW9662 (PPARγ inhibitor) inhibited PTEN protein expression and recovered PASMCs proliferation rate.
  
  
  CONCLUSIONS
  BMP-2 increased PTEN expression under hypoxia in a dose dependent pattern. BMP-2 reduced AKT activity and increased caspase activity of PASMCs under hypoxia. The increased PTEN expression may be mediated through PPARγ signalling pathway, instead of BMP/Smad signalling pathway.
authors.affiliation: Department of Respiratory Medicine, Xinhua Hospital, School of Medicine, Jiaotong University, Shanghai, China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Pi
authors.forename: Xuejun
authors.initials: X
authors.lastname: Guo
authors.forename: Liping
authors.initials: L
authors.lastname: Su
authors.forename: Weiguo
authors.initials: W
authors.lastname: Xu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D017931:DNA Primers; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D055396:Bone Morphogenetic Protein 2; D017931:DNA Primers; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human