Multiple signal transduction pathways through two prostaglandin E receptor EP3 subtype isoforms expressed in human uterus.
PGE2 is known to induce uterine contraction by increasing intracellular Ca2+. In the present study, to investigate other functions of PGE2 in human uterus, two EP3 isoforms were isolated by the RT-PCR method using human uterus polyadenylated ribonucleic acid (RNA). These EP3 isoforms, named EP3-V and EP3-VI, are composed of 402 and 393 amino acid residues, respectively, which are unique compared with EP3 isoforms of other species. Their N-terminal 359 amino acid residues are identical to those of previously reported human EP3 isoforms, whereas the two isoforms contained a novel amino acid sequence in their C-terminal tails. The dissociation constant values of EP3-V and EP3-VI for PGE2 were 3.9 and 1.4 nmol/L, respectively, which were consistent with those of previously reported EP3 isoforms. Signaling experiments revealed that M&B28767, an EP3 agonist, not only inhibited forskolin-induced cAMP concentrations, but also activated mitogen-activated protein kinase in Chinese hamster ovary cells stably expressing EP3-V and EP3-VI. These responses were abolished by treatment with pertussis toxin. In addition, M&B28767 increased cAMP concentrations in EP3-VI-expressing cells, whereas it did not in EP3-V-expressing cells. M&B28767 did not stimulate phosphoinositide turnover in EP3-V or EP3-VI-expressing cells. EP3-V and EP3-VI messenger RNAs (mRNAs) were detected abundantly in human uterus, whereas weak, but substantial, bands were detected in the lung and kidney in RT-PCR specific for each mRNA. In situ hybridization revealed EP3-V and EP3-VI mRNAs in the human myometrium, but not in the endometrium. The present study suggests that EP3-V and EP3-VI are possibly involved in the proliferation of cells in human myometrium.
Kotani
M
M
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Japan.
Tanaka
I
I
Ogawa
Y
Y
Suganami
T
T
Matsumoto
T
T
Muro
S
S
Yamamoto
Y
Y
Sugawara
A
A
Yoshimasa
Y
Y
Sagawa
N
N
Narumiya
S
S
Nakao
K
K
D000527:Alprostadil / Q000031:analogs & derivatives* / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000235:genetics / Q000502:physiology*; D058308:Receptors, Prostaglandin E, EP3 Subtype; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection; D014599:Uterus / Q000502:physiology*
C545647:PTGER3 protein, human; D020033:Protein Isoforms; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D058308:Receptors, Prostaglandin E, EP3 Subtype; D011994:Recombinant Proteins; D005576:Colforsin; C032405:11-deoxy-16-phenoxy-17,18,19,20-tetranorprostaglandin E1; D000242:Cyclic AMP; D000527:Alprostadil