Progestin and adipoQ Receptor 7, Progesterone Membrane Receptor Component 1 (PGRMC1) and PGRMC2 and Their Role in Regulating Progesterone's Ability to Suppress Human Granulosa/Luteal Cells from Entering into the Cell Cycle. Sueldo C et al. (2015) The present studies were designed to determine the role of Progesterone Receptor Membrane Component 1 (PGRMC1), PGRMC2, Progestin and AdipoQ Receptor 7 (PAQR7) and Progesterone Receptor (PGR) in mediating the anti-mitotic action of progesterone (P4) in human granulosa/luteal cells. For these studies granulosa/luteal cells of ten women undergoing controlled ovarian hyperstimulation were isolated, maintained in culture, and depleted of PGRMC1, PGRMC2, PAQR7 or PGR by siRNA treatment. The rate of entry into the cell cycle was assessed using the FUCCI cell cycle sensor to determine the percentage of cells in the G1/S stage of the cell cycle. PGRMC1, PGRMC2, PAQR7 or PGR mRNA levels were assessed by real-time PCR and their interactions monitored by in situ proximity ligation assays (PLAs). These studies revealed that PGRMC1, PGRMC2, PAQR7 and PGR were expressed by granulosa/luteal cells from all patients with PGRMC1 mRNA being most abundant followed by PAQR7, PGRMC2 and PGR. However, their mRNA levels showed considerable patient variation. P4's ability to suppress entry into the cell cycle was dependent on PGRMC1, PGRMC2 and PAQR7 but not PGR. Moreover, PLAs indicated that PGRMC1, PGRMC2 and PAQR7 formed a complex within the cytoplasm. Based on these studies, it is proposed that these three P4 mediators form a complex within the cytoplasm that is required for P4's action. Moreover, P4's ability to regulate human follicle development may be dependent in part on the expression levels of each of these P4 mediators.//////////////////
Expression regulated by
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Ovarian localization
Luteal cells
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Expression and Regulation of Progestin Membrane Receptors in the Rat Corpus Luteum Cai Z, et al .
Despite evidence strongly supporting progesterone's autocrine actions in the rat corpus luteum (CL), classical progesterone receptors (PR) have not been detected in this gland. Alternatively, in several other systems, progestins have been reported to activate non-genomic pathways via putative progestin membrane receptors (PMRs). The aim of this investigation was to determine whether rat CL membranes bind progestins and contain PMR homologs, and whether these proteins are expressed during CL development in a manner that parallels luteal function. We found that luteal cell membranes specifically bind progesterone. Low levels of progesterone and 20alpha-dihydroprogesterone decreased binding of (3)H-progesterone, whereas androstendione, 17alpha-hydroxyprogesterone, and pregnenolone were less potent. Other steroids, including corticosterone, mifepristone, and estradiol, were ineffective. We found that the rat CL expresses five genes previously postulated to encode for putative PMRs: PMRalpha, PMRbeta, PMRgamma, PR membrane component 1 (PRMC1), and Rda288. Pmralpha, Pmrgamma, and Prmc1 transcripts rose steadily during pregnancy whereas Pmrbeta and Rda288 remained constant. Just before parturition, concomitant with falling progesterone levels, Pmralpha, Pmrbeta, and Prmc1 decreased. Luteal PMRalpha and PRMC1 protein levels were lower in samples taken at the end of pregnancy compared with mid-pregnancy samples. Ergocriptine, which inhibits the secretion of prolactin, the primary luteotrophic hormone in the rat CL, reduced Pmralpha, Pmrbeta, and Prmc1 expression significantly. Ergocriptine effects were prevented by co-administration of prolactin. These findings provide evidence for the expression and regulation of putative membrane-bound progestin binding proteins in the rat CL, a tissue that does not express detectable levels of nuclear progesterone receptors.
Follicle stages
Corpus luteum
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Cloning and characterization of an ovine intracellular seven transmembrane receptor for progesterone that mediates calcium mobilization. Ashley RL et al. Classically, progesterone has been thought to act only through the well-known genomic pathway involving hormone binding to nuclear receptors (nPR) and subsequent modulation of gene expression. However, there is increasing evidence for rapid, nongenomic effects of progesterone in a variety of tissues in mammals and it seems likely that a membrane PR (mPR) is causing these events. The objective of this study was to isolate and characterize an ovine mPR distinct from the nPR. A cDNA clone was isolated from ovine genomic DNA by PCR. The ovine mPR is a 350 amino acid protein that, based on computer hydrophobicity analysis, possesses seven transmembrane domains and is distinct from the nPR. Message for the ovine mPR was detected in hypothalamus, pituitary, uterus, ovary and corpus luteum by RT-PCR. In CHO cells that overexpressed a mPR-GFP fusion protein the ovine mPR was localized to the endoplasmic reticulum and not the plasma membrane. Specific binding of (3)H-progesterone to membrane fractions was demonstrated in CHO cells that expressed the ovine mPR, but not in nontransfected cells. Furthermore, progesterone and 17-alpha-hydroxy- progesterone stimulated intracellular Ca(2+) mobilization in CHO cells which expressed ovine mPR in Ca(2+)-free medium (P < 0.05) but not in CHO cells transfected with empty vector. This rise in intracellular Ca(2+) is believed to be from the endoplasmic reticulum as intracellular Ca(2+) mobilization is absent when mPR transfected cells are first treated with thapsigargin, to deplete Ca(2+) stores from the endoplasmic reticulum. Isolation, identification, tissue distribution, cellular localization, steroid binding, and a functional response for a unique intracellular mPR in the sheep are presented.