Cloned human EP1 prostanoid receptor pharmacology characterized using radioligand binding techniques.
Prostaglandins such as prostaglandin E2 (PGE2) interact with EP-class prostanoid receptors including EP1, EP2, EP3 and EP4 subtypes. We have conducted a detailed pharmacological characterization of the binding of [3H]-PGE2 to recombinant human EP1 prostanoid receptors expressed in human embryonic kidney (HEK-293) cells using a broad panel of natural and synthetic prostanoids. The receptor displayed high affinity (Kd = 16.0 +/- 0.69 nM; n = 3) for [3H]-PGE2, and was expressed at high levels (Bmax =3.69 +/- 0.30 pmol (mg protein)(-1)) in cell membranes of HEK-293 cells. Specific binding constituted 97.5 +/- 1.4% (n = 12) of the total binding. In competition assays, the rank order of affinities of natural prostanoids for the receptor was PGE2 > PGE1 > PGF2 > PGI2 > PGD2. PGE2 was more effective than PGE1 at displacing bound [3H]-PGE2 (Ki for PGE2 = 14.9 +/- 2.2 nM; Ki for PGE1 = 165 +/- 29 nM). The affinities of enprostil (Ki = 14.5 +/- 3.1 nM) and 17-phenyl-omega-trinor-PGE2 (Ki = 7.3 +/- 2.7 nM) for the receptor were quite similar to that of PGE2, while that of sulprostone (Ki = 137 + 13 nM) more closely resembled PGE1. Some compounds historically classified as specific for DP prostanoid receptors bound with relatively high affinity to the recombinant human EP1 receptor (e.g. ZK118182 (K = 73.4 +/- 8.6 nM) and ZK110841 (K = 166 +/- 20 nM)). All FP (e.g. travoprost acid, fluprostenol), IP (iloprost) and TP (SQ29548) receptor-specific ligands exhibited low affinity (Ki > or = 1 microM).
Sharif
Najam A
NA
Molecular Pharmacology Unit, Alcon Research, Ltd, Fort Worth, Texas 76134, USA. naj.sharif@alconlabs.com
Davis
Terry L
TL
D000465:Algorithms; D000527:Alprostadil / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003001:Cloning, Molecular; D004274:DNA, Recombinant; D015237:Dinoprost / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D011464:Epoprostenol / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D015230:Prostaglandin D2 / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology*; D011869:Radioligand Assay; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism*; D058306:Receptors, Prostaglandin E, EP1 Subtype; D014316:Tritium
D004274:DNA, Recombinant; D008024:Ligands; C545635:PTGER1 protein, human; D011458:Prostaglandins E; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D014316:Tritium; D015237:Dinoprost; D011464:Epoprostenol; D000527:Alprostadil; D015232:Dinoprostone; D015230:Prostaglandin D2