Molecular cloning and expression of multiple isoforms of human prostaglandin E receptor EP3 subtype generated by alternative messenger RNA splicing: Multiple second messenger systems and tissue-specific distributions

Masato Kotani, Issei Tanaka, Yoshihiro Ogawa, Takeshi Usui, Kiyoshi Mori, Atsushi Ichikawa, Shuh Narumiya, Teruya Yoshimi, Kazuwa Nakao

Research output: Contribution to journalArticlepeer-review

126 Citations (Scopus)

Abstract

Five distinct cDNA clones encoding four different isoforms of human prostaglandin (PG) E receptor EP3 subtype were isolated from a human kidney cDNA library. Two cDNA clones differed only in their 3′-untranslated regions. The four isoforms, tentatively named EP3-III, EP3-II, EP3-III, and EP3-IV, which were generated by alternative mRNA splicing, had identical amino acid sequences except for their different carboxyl-terminal tails. Transfection experiments revealed that all the four isoforms show high binding affinities to PGE2, PGE1, and M&B28767, an EP3-specific agonist, whereas their down- stream signaling pathways are divergent. M&B28767 increased cAMP concentrations in cells expressing EP3-II and EP3-IV, whereas it inhibited forskolin-induced cAMP accumulations in cells expressing all EP3 isoforms. M&B28767 also stimulated phosphoinositide turnover in cells expressing EP3-I and EP3-II. Northern blot analysis revealed that the EP3 gene is expressed in a wide variety of human tissues. The human EP3 mRNA was present most abundantly in the kidney, pancreas, and uterus. A substantial expression was also detected in the heart, liver, skeletal muscle, small intestine, colon, prostate, ovary, and testis. Furthermore, reverse transcription-polymerase chain reaction analysis demonstrated tissue-specific expressions of the five different EP3 mRNA species. The present study suggests the presence of the multiple systems of PGE2/EP3 isoforms and leads to the better understanding of its physiological and pathophysiological implications in humans.

Original languageEnglish
Pages (from-to)869-879
Number of pages11
JournalMolecular Pharmacology
Volume48
Issue number5
Publication statusPublished - Nov 1995
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Pharmacology

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