8-iso-PGE2 stimulates anion efflux from airway epithelial cells via the EP4 prostanoid receptor

Andrew P. Joy, Elizabeth A. Cowley

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Isoprostanes are biologically active molecules, produced when reactive oxygen species mediate the peroxidation of membrane polyunsaturated fatty acids. Previous work has demonstrated that the isoprostane 8-iso-prostaglandin E 2 (PGE2) stimulates cystic fibrosis transmembrane conductance regulator (CFTR)-mediated transepithelial anion secretion across the human airway epithelial cell line, Calu-3. Since isoprostanes predominantly achieve their effects via binding to prostanoid receptors, we hypothesized that this 8-iso-PGE2 stimulation of CFTR activity was the result of the isoprostane binding to a prostanoid receptor. Using RT-PCR, immunoblotting, and immunofluorescence, we here demonstrate that Calu-3 cells express the EP 1-4 and FP receptors, and localize these proteins in polarized cell monolayers. Using iodide efflux as a marker for CFTR-mediated Cl- efflux, we investigate whether prostanoid receptor agonists elicit a functional response from Calu-3 cells. Application of the agonists PGE2, misoprostol (EP2, EP3, and EP4) and PGE 1-OH (EP3 and EP4) stimulate iodide efflux; however, iloprost, butaprost, sulprostone, and fluoprostenol (agonists of the EP1, EP2, EP3, and FP receptors, respectively) have no effect. The iodide efflux seen with 8-iso-PGE2 is abolished by the EP4 receptor antagonist AH23848, the CFTR inhibitor 172, and inhibition of PKA and the PI3K pathway. In conclusion, we demonstrate that although Calu-3 cells possess numerous prostanoid receptors, only the EP 4 subtype appears capable of eliciting a functional iodide efflux response, which is mediated via the EP4 receptor. We propose that 8-iso-PGE2, acting via EP4 receptor, could play an important role in the CFTR-mediated response to oxidant stress, and which would be compromised in the CF airways.

Original languageEnglish
Pages (from-to)143-152
Number of pages10
JournalAmerican Journal of Respiratory Cell and Molecular Biology
Volume38
Issue number2
DOIs
Publication statusPublished - Feb 2008

ASJC Scopus Subject Areas

  • Molecular Biology
  • Pulmonary and Respiratory Medicine
  • Clinical Biochemistry
  • Cell Biology

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