title: Contribution of myocardin in the hypoxia-induced phenotypic switching of rat pulmonary arterial smooth muscle cells.
abstract: BACKGROUND
  Hypoxic exposure contributes to the phenotypic switching of smooth muscle cells (SMCs), while the mechanisms involved in this process is not yet fully elucidated. Myocardin as a co-actor of serum reaction factor plays a crucial role in differentiation of SMCs. This study was aimed to investigate the role of myocardin in hypoxia-induced phenotypic switching of rat pulmonary arterial SMCs (PASMCs).
  
  
  METHODS
  Primary PASMCs were cultured under normoxia and hypoxia (3%O(2), 48 h) respectively, and then the cell proliferation was assessed and the expression of SM22α, osteopontin (contractile and synthetic marker of SMCs, respectively), myocardin and platelet-derived growth factor-BB (PDGF-BB) were detected. After pGCSIL-GFP-shMYOCD lentviral vector was transduced to the PASMCs, the expression of myocardin and SM22α were examined. Moreover, myocardin expression in PASMCs treated with medium enriched with PDGF-BB and conditional medium (CM) from normoxia- and hypoxia-exposed PASMCs was assessed.
  
  
  RESULTS
  Exposing PASMCs to hypoxia led to an increased cell numbers and the up-regulation of proliferating cell nuclear antigen (PCNA), osteopontin and PDGF-BB; moreover, a significant down-regulation of SM22α and myocardin was identified. Further analysis revealed that knock-down of myocardin with pGCSIL-GFP-shMYOCD vector followed by a decreased SM22α in the PASMCs, and treatment of PASMCs with either exogenous PDGF-BB or hypoxic CM led to a marked decrease of myocardin.
  
  
  CONCLUSIONS
  Our findings suggest that the decrease of myocardin in PASMCs exposed to hypoxia is partly regulated by the increase of PDGF-BB, which contributes to the phenotypic switching of PASMCs in hypoxic condition.
authors.affiliation: Institute of Pathology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jie
authors.forename: Junli
authors.initials: J
authors.lastname: Guo
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Shen
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.forename: Shaojiang
authors.initials: S
authors.lastname: Zheng
authors.forename: Guoping
authors.initials: G
authors.lastname: Wang
authors.forename: Qilin
authors.initials: Q
authors.lastname: Ao
mesh_terms: D000818:Animals; D000077214:Becaplermin; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000096:biosynthesis*; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D011651:Pulmonary Artery / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000096:biosynthesis*; D000099251:Myocardin
chemical_list: D000077214:Becaplermin; D009687:Nuclear Proteins; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D015534:Trans-Activators; D000099251:Myocardin