Interactions between progesterone receptor isoforms in myometrial cells in human labour

Progesterone acts to maintain uterine quiescence during pregnancy. In contrast to many other species, no decrease in maternal serum levels of progesterone can be observed in humans before the onset of labour. Therefore, a `functional' progesterone withdrawal in association with labour has been...

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Bibliographic Details
Published in:Molecular human reproduction 2001-09, Vol.7 (9), p.875-879
Main Authors: Pieber, Doris, Allport, Victoria C., Hills, Frank, Johnson, Mark, Bennett, Phillip R.
Format: Article
Language:English
Subjects:
Biological and medical sciences
Cells, Cultured
Cesarean Section
Female
Fundamental and applied biological sciences. Psychology
Humans
Labor, Obstetric - genetics
Labor, Obstetric - metabolism
labour
Mother. Fetoplacental unit. Mammary gland. Milk
myometrium
Myometrium - chemistry
Myometrium - cytology
Myometrium - metabolism
parturition
Pregnancy
Pregnancy. Parturition. Lactation
progesterone receptor
Protein Isoforms - genetics
Protein Isoforms - metabolism
Receptors, Progesterone - biosynthesis
Receptors, Progesterone - genetics
Receptors, Progesterone - metabolism
Transcriptional Activation
Vertebrates: reproduction
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Summary:Progesterone acts to maintain uterine quiescence during pregnancy. In contrast to many other species, no decrease in maternal serum levels of progesterone can be observed in humans before the onset of labour. Therefore, a `functional' progesterone withdrawal in association with labour has been proposed. In humans the progesterone receptor (PR) exists in two isoforms, PR-A and PR-B. While PR-B generally mediates the effects of progesterone upon gene transcription, the role of PR-A during pregnancy, and in parturition, is unknown. In this study, term myometrium cells cultured before the onset of labour were transiently transfected with expression vectors for either PR-A or PR-B. Only those cells expressing PR-B significantly increased expression of a progesterone-sensitive reporter when stimulated with progesterone. Co-transfection of both isoforms of PR demonstrated that PR-A is a dominant repressor of transactivation in these cells. Western blot analysis showed that PR-A is present in human myometrium samples taken only after, but not before, the onset of labour. These data suggest that increased expression of PR-A in human myometrium may contribute to `functional' progesterone withdrawal and the initiation of human labour.
ISSN:1360-9947
1460-2407
1460-2407
DOI:10.1093/molehr/7.9.875