Suppression of Akt1 phosphorylation by adenoviral transfer of the PTEN gene inhibits hypoxia-induced proliferation of rat pulmonary arterial smooth muscle cells

Biochem Biophys Res Commun. 2010 Jul 2;397(3):486-92. doi: 10.1016/j.bbrc.2010.05.140. Epub 2010 May 31.

Abstract

Recent findings identify the role of proliferation of pulmonary artery smooth muscle cells (PASMCs) in pulmonary vascular remodeling. Phosphoinositide 3 kinase (PI3K) and serine/threonine kinase (Akt) proteins are expressed in vascular smooth muscle cells. In addition, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been identified as a negative regulator of cytokine signaling that inhibits the PI3K-Akt pathway. However, little is known about the role of PTEN/Akt signaling in hypoxia-associated vascular remodeling. In this study, we found that hypoxia-induced the expression of Akt1 mRNA and phosphorylated protein by at least twofold in rat PASMCs. Phospho-PTEN significantly decreased in the nuclei of PASMCs after hypoxic stimulation. After forcing over-expression of PTEN by adenovirus-mediated PTEN (Ad-PTEN) transfection, the expression of phospho-Akt1 was significantly suppressed in PASMCs at all time-points measured. Additionally, we showed here that hypoxia increased proliferation of PASMCs by nearly twofold and over-expression of PTEN significantly inhibited hypoxia-induced PASMCs proliferation. These findings suggest that phospho-PTEN loss in the nuclei of PASMCs under hypoxic conditions may be the major cause of aberrant activation of Akt1 and may, therefore, play an important role in hypoxia-associated pulmonary arterial remodeling. Finally, the fact that transfection with Ad-PTEN inhibits the phosphorylation of Akt1 in PASMCs suggests a potential therapeutic effect on hypoxia-associated pulmonary arterial remodeling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae
  • Animals
  • Cell Line
  • Cell Proliferation*
  • Gene Transfer Techniques
  • Hypoxia / genetics
  • Hypoxia / pathology*
  • Myocytes, Smooth Muscle / pathology*
  • PTEN Phosphohydrolase / genetics*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Pulmonary Artery / pathology*
  • Rats
  • Suppression, Genetic

Substances

  • Proto-Oncogene Proteins c-akt
  • PTEN Phosphohydrolase