Expression and function of myometrial PSF suggest a role in progesterone withdrawal and the initiation of labor.
Progesterone (P4), acting through its receptor (PR), is essential for the maintenance of pregnancy. P4 acts by suppressing uterine contractility and the expression of contraction-associated proteins (CAP) such as connexin 43 (Cx43). P4 levels must be reduced or its actions blocked to allow the increased expression of CAP genes and the initiation of labor. Although the importance of progesterone in pregnancy has been known for about 80 yr, the fundamental mechanisms by which P4/PR maintains myometrial quiescence and by which this signaling is blocked at term labor remain to be determined. In this manuscript, we demonstrate that ligand-bound PR interacts with the Cx43 gene promoter through activator protein-1 transcription factors. We show that the ability of PR to repress Cx43 transcription is conferred through the recruitment of the PR coregulator, polypyrimidine tract binding protein-associated splicing factor (PSF), and the further recruitment of the yeast switch independent 3 homolog A/histone deacetylase corepressor complex. PSF expression is elevated during pregnancy but falls toward term as a result of increased mechanical stretch of the myometrium and a rise in the concentrations of circulating estrogen. These data together indicate that PSF is a critical regulator of P4/PR signaling and labor. We suggest that decreased PSF at term may result in a de-repression of PR transcriptional control of CAP genes and thereby contributes to a functional withdrawal of progesterone at term labor.
Vancouver Prostate Center, Department of Urologic Sciences, University of British Columbia, Vancouver Canada.
Ning
N
Xie
Liangliang
L
Liu
Yunqing
Y
Li
Celeste
C
Yu
Stephanie
S
Lam
Oksana
O
Shynlova
Martin
M
Gleave
John R G
JR
Challis
Stephen
S
Lye
Xuesen
X
Dong
D000818:Animals; D001696:Biomechanical Phenomena; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D004958:Estradiol / Q000502:physiology; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D008297:Male; D009215:Myometrium / Q000166:cytology / Q000378:metabolism*; D000072670:PTB-Associated Splicing Factor; D011247:Pregnancy; D011374:Progesterone / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011980:Receptors, Progesterone / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D018031:Connexin 43; D000072670:PTB-Associated Splicing Factor; D016601:RNA-Binding Proteins; D011980:Receptors, Progesterone; D018808:Transcription Factor AP-1; D011374:Progesterone; D004958:Estradiol