Prostaglandin F(2alpha) receptor-dependent regulation of prostaglandin transport.
Prostaglandin (PG) F(2alpha) may act on its G protein-coupled receptor (FP) or be imported intracellularly via a transporter, which has high affinity for PGF(2alpha) and PGE(2), but not prostacyclin (PGI(2)). In cells overexpressing the epitope-tagged FP together with the human prostaglandin transporter (hPGT), stimulation of the FP with PGF(2alpha) (1 nM-1 microM), or the less potent FP agonist, the isoprostane 8,12-iso-iPF(2alpha)-III, inhibited prostaglandin uptake via the hPGT. This effect was abolished by pretreatment of the cells with cholera toxin, but not with pertussis toxin. Furthermore, two dominant negative constructs directed against Galpha(s) partially blocked FP-mediated regulation of hPGT function, also suggesting Galpha(s) involvement in this phenomenon. Surprisingly, neither an activator (dibutyryl cyclic AMP) nor an inhibitor (H89) of cyclic AMP-dependent protein kinase had any effect on FP-mediated inhibition of hPGT activity. Furthermore, although PGF(2alpha) increases intracellular cyclic AMP via Galpha(s) activation, it does not induce phosphorylation of the transporter, excluding a role of cyclic AMP-dependent protein kinase in hPGT regulation. Activation of the PGI(2) receptor, which is also coupled to Galpha(s), does not regulate hPGT activity, despite markedly augmenting adenylate cyclase activation. In conclusion, activation of the FP reduces intracellular import of prostaglandins for metabolic inactivation, increasing prostanoid availability for membrane receptor activation. This effect seems to be mediated via Galpha(s), independent of adenylate cyclase and cyclic AMP-dependent protein kinase activation.
Vezza
R
R
Center for Experimental Therapeutics, University of Pennsylvania, 153 Johnson Pavilion, 3600 Hamilton Walk, Philadelphia, PA 19104, USA.
Rokach
J
J
FitzGerald
G A
GA
D017920:Antiporters / Q000187:drug effects / Q000378:metabolism; D001692:Biological Transport; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D015237:Dinoprost / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D027361:Organic Anion Transporters; D011453:Prostaglandins / Q000378:metabolism*; D011982:Receptors, Prostaglandin / Q000378:metabolism*
C114340:8,12-iso-isoprostane F2alpha-III; D017920:Antiporters; D004268:DNA-Binding Proteins; D027361:Organic Anion Transporters; D011453:Prostaglandins; D011982:Receptors, Prostaglandin; C503526:SLCO2A1 protein, human; C034671:prostaglandin F2alpha receptor; D015237:Dinoprost; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins