Differential regulation of Ca2+-dependent Cl currents by FP prostanoid receptor isoforms in Xenopus oocytes

Todd L. Anthony, Hiromichi Fujino, Kristen L. Pierce, Andrea J. Yool, John W. Regan

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The FPA and FPB prostanoid receptor isoforms are G-protein-coupled receptors that are activated by prostaglandin F (PGF). Differences in their carboxyl termini prompted us to examine the intracellular calcium (Ca2+) signaling of these receptor isoforms using the Xenopus oocyte expression system. Protein expression was determined by immunofluorescence microscopy and whole cell binding with [3H]PGF. Positive immunolabeling was observed on the outer membranes of oocytes expressing FLAG-tagged FP receptor isoforms, but not on control (water-injected) oocytes. Intracellular signaling was examined using a two-electrode voltage clamp. Specific whole-cell binding was also detected for both receptor isoforms. Bath application of 10μM PGF to FPA-expressing oocytes produced a chloride (Cl-) current response similar to that of an injection of inositol 1,4,5-trisphosphate (InsP3) (5.76±0.6μA, peak current; N=23) that returned to control levels within 25min. In FPB-expressing oocytes the activation of the Cl- current was delayed or completely absent (1.38±0.2μA, peak current; N=18). Control oocytes were not responsive to the application of PGF (0.87±0.1μA, peak current; N=10). Activation of Cl- currents for both FP receptor isoforms was dependent upon intracellular Ca2+ stores as a 30-min pretreatment with thapsigargin (1μM; N=5) blocked the PGF induction of the Cl- current. These data indicate that the FP prostanoid receptor isoforms differ in their ability to activate Ca2+-dependent Cl- channels when expressed in Xenopus oocytes. The difference appears to be in the ability of the two FP prostanoid receptor isoforms to mobilize intracellular calcium.

Original languageEnglish (US)
Pages (from-to)1797-1806
Number of pages10
JournalBiochemical Pharmacology
Volume63
Issue number10
DOIs
StatePublished - May 15 2002

Keywords

  • Calcium
  • Chloride channel
  • PGF
  • Prostaglandin
  • Xenopus

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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