Developmental differences in the shear stress-induced expression of endothelial NO synthase: Changing role of AP-1

Stephen Wedgwood, Calista J. Mitchell, Jeffrey R. Fineman, Stephen M. Black

Research output: Contribution to journalArticle

60 Scopus citations

Abstract

Endothelial nitric oxide synthase (eNOS) mRNA and protein levels increase during late gestation and then decrease postnatally in sheep lung parenchyma. The increase in fluid shear stress at birth, resulting from increased pulmonary blood flow, is an important mediator of postnatal eNOS gene expression. Our objective was to identify factors stimulating eNOS expression in pulmonary arterial endothelial cells (PAEC) in response to shear stress and to determine if these factors are developmentally regulated. PAEC were isolated from fetal lambs and adult sheep. Transcriptional activity from a 1,600-bp eNOS promoter fragment increased in both fetal and adult PAEC exposed to 8 h of shear stress. Conversely, activity driven from an 840-bp promoter fragment containing a putative activator protein (AP)-1 binding site was increased only in fetal PAEC. This increase was completely abolished in an identical construct containing a mutant AP-1 sequence. The AP-1 protein c-Jun was localized to the cytosol in static adult PAEC and to the nucleus in static fetal PAEC. After shear, c-Jun was nuclear localized in both cell types. However, transcriptionally active phosphorylated c-Jun was elevated only in the nuclei of sheared fetal PAEC. Resting levels of eNOS and NO were 2- and 20-fold higher, respectively, in fetal cells. Shear increased eNOS and NO in both cell types: levels were -2.5-fold higher in fetal PAEC. Phosphorylation of Akt and eNOS was evident in sheared fetal but not adult PAEC. We have therefore identified mechanisms of eNOS regulation at the transcriptional level and to be enzyme activation specific to the fetal pulmonary arterial circulation.

Original languageEnglish (US)
Pages (from-to)L650-L662
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume284
Issue number4 28-4
StatePublished - Apr 1 2003

Keywords

  • Activator protein-1
  • Fetal sheep
  • Gene expression
  • Maturational differences
  • Nitric oxide
  • Protein translocation
  • Pulmonary arterial endothelial cells

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

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