Endothelin A and B receptors change their expression levels during development of human placental villi.
Endothelin receptors have recently been found in non-vascular tissues including the human placenta. The present study investigated developmental changes in location and expression levels of endothelin A and B receptors (ETA-R, ETB-R) in human placentae and isolated trophoblast by comparing first and third trimester tissues. In the first trimester all cells and tissues were immunolabelled for ETA-R and ETB-R, whereas in third trimester placentae the syncytiotrophoblast (ETA-R, ETB-R) and macrophages (ETA-R) were unstained. Immunoblotting for both receptors revealed up to three bands at 33-35, 50 and 75 kDa, respectively, which were differentially present in the first and third trimester. Pre-adsorption of antibodies with oligopeptides used for antigen-generation weakened the immunoreactions. ETA-R protein levels decreased (P< 0.05) in total villous tissue and isolated trophoblast, whereas ETB-R was unchanged. ETB-R transcripts (RT-PCR) prevailed in both stages and tissues, but in contrast to the protein levels its preponderance decreased from first trimester to term in villous tissue (P< 0.01), because of a four to five-fold increase in ETA-R and only a two-fold (P< 0.05) increase in ETB-R mRNA levels (P< 0.01). We conclude that ET receptor location, intracellular processing and expression levels in human villous tissue change between the first and third trimester. This may reflect changing functions of ET-1 during placental development.
Department of Obstetrics and Gynaecology, Karl-Franzens-University of Graz, Austria.
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M
Cervar
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Huppertz
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Barth
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T
Hahn
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U
Weiss
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P
Kaufmann
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Desoye
D000029:Abortion, Legal; D000032:Abortion, Therapeutic; D000328:Adult; D015153:Blotting, Western; D002824:Chorionic Villi / Q000196:embryology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008969:Molecular Sequence Data; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000378:metabolism; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014327:Trophoblasts / Q000378:metabolism
D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D012313:RNA