Isoforms of the EP3 subtype of human prostaglandin E2 receptor transduce both intracellular calcium and cAMP signals.
The EP3 subtype of prostaglandin E2 receptor transduces diverse physiological responses in mammalian tissues through signaling pathways coupled to heterotrimeric G proteins. Distinct cDNA clones encoding five isoforms of the EP3 receptor were isolated from a human uterus cDNA library. The human EP3 receptor isoforms designated hEP3-I, I', II, III, and IV are derived from alternative RNA splicing and differ only in the distal sequences of their carboxyl-terminal cytoplasmic tails. The unique cytoplasmic tails consist of 31 amino acids for isoforms I and I', 29 for II, 6 for III, and 15 for IV. When stably expressed in CHO cell transfectants, all isoforms exhibited similar EP3-specific binding of [3H]-PGE2 and PGE2 analogs. The EP3-selective agonist M&B 28767 both decreased the intracellular cAMP concentration ([cAMP]i) and increased the intracellular concentration of calcium ([Ca2+]i) with quantitative differences among different isoforms, but none mediated an increase in [cAMP]i. Pertussis toxin treatment completely blocked the decrease in [cAMP]i, but not the increase in [Ca2+]i evoked by M&B 28767. PGE2-induced desensitization of [3H]PGE2 binding by isoforms III and IV was rapid and transient, whereas that by isoform II was slow and persistent. Reverse transcription-PCR amplification of EP3 receptor messages in human kidney and uterine tissue RNA detected expression of all isoforms with different abundancies. The dual signal transduction pathways and distinctive tissue distribution of isoforms of the EP3 receptor are consistent with its mediation of diverse functions of PGE2.
An
S
S
Department of Medicine, University of California, San Francisco 94143-0711.
Yang
J
J
So
S W
SW
Zeng
L
L
Goetzl
E J
EJ
D000527:Alprostadil / Q000031:analogs & derivatives / Q000494:pharmacology; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002118:Calcium / Q000502:physiology*; D006224:Cricetinae; D000242:Cyclic AMP / Q000502:physiology*; D017931:DNA Primers / Q000737:chemistry; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D037342:Pertussis Toxin; D012333:RNA, Messenger / Q000235:genetics; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D017931:DNA Primers; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; C032405:11-deoxy-16-phenoxy-17,18,19,20-tetranorprostaglandin E1; D000242:Cyclic AMP; D037342:Pertussis Toxin; D000527:Alprostadil; D002118:Calcium