Regulation of fibroblast growth factor-2 expression in pulmonary arterial smooth muscle cells involves increased reactive oxygen species generation

Stephen Matthew Black, Jennifer M. DeVol, Stephen Wedgwood

Research output: Contribution to journalArticle

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Abstract

We have previously demonstrated increased fibroblast growth factor-2 (FGF-2) expression in a lamb model of increased pulmonary blood flow secondary to congenital heart disease, which may contribute to the associated increases in pulmonary arterial muscularization. However, the mechanisms underlying these increases in FGF-2 expression remain to be identified. Initially, we found that exogenous FGF-2 increased endogenous FGF-2 promoter activity and protein levels in ovine pulmonary arterial smooth muscle cells (PASMC). Furthermore, we found that these increases in FGF-2 expression were mediated by increases in superoxide levels via NADPH oxidase activation. In addition, FGF-2-mediated increases in FGF-2 expression and PASMC proliferation were attenuated by inhibition of phosphatidylinositol 3-kinase, Akt, and NADPH oxidase. Increases in FGF-2 expression could be stimulated by other factors known to increase reactive oxygen species (ROS) signaling in PASMC (endothelin-1 and transforming growth factor-β1), whereas antioxidants attenuated these increases. Deletion constructs localized the growth factor- and ROS-sensitive region within the proximal 103 bp of the FGF-2 promoter, and sequence analysis identified a putative hypoxia response element (HRE), a DNA binding site for the ROS-sensitive transcription factor hypoxia-inducible factor-1α (HIF-1α). Stabilization of HIF-1α increased FGF-2 promoter activity, whereas mutation of the putative HRE attenuated FGF-2-induced FGF-2 promoter activity. Furthermore, FGF-2 increased HIF-1α protein levels and consensus HRE promoter activity in PASMC via antioxidant-sensitive mechanisms. Thus we conclude that FGF-2 can stimulate its own expression in PASMC via NADPH oxidase-mediated activation of ROS-sensitive transcription factors, including HIF-1α. This positive feedback mechanism may contribute to pulmonary vascular remodeling associated with increased pulmonary blood flow.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume294
Issue number1
DOIs
StatePublished - Jan 1 2008

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Fibroblast Growth Factor 2
Smooth Muscle Myocytes
Muscle
Reactive Oxygen Species
Cells
Lung
Hypoxia-Inducible Factor 1
NADPH Oxidase
Response Elements
Blood
Transcription Factors
Antioxidants
Chemical activation
Phosphatidylinositol 3-Kinase
Secondary flow
Cell proliferation
Transforming Growth Factors
Endothelin-1
Superoxides
Sequence Analysis

Keywords

  • Cell signaling
  • Proliferation
  • Pulmonary hypertension

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Regulation of fibroblast growth factor-2 expression in pulmonary arterial smooth muscle cells involves increased reactive oxygen species generation. / Black, Stephen Matthew; DeVol, Jennifer M.; Wedgwood, Stephen.

In: American Journal of Physiology - Cell Physiology, Vol. 294, No. 1, 01.01.2008.

Research output: Contribution to journalArticle

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