Expression Of Membrane Progesterone Receptors Research Articles

Functional Implications of Estrogen and Progesterone Receptors Expression in Adenomyosis, Potential Targets for Endocrinological Therapy.

Adenomyosis is a common gynaecological disease associated with the presence of endometrial lesions in the uterine myometrium. Estrogens have been proven to be the crucial hormones driving the growth of adenomyosis. Little is known about the distinct mechanisms of progesterone action in adenomyosis. Hence, in this study, we decided to characterize the expression of all nuclear and membrane estrogen and progesterone receptors. Additionally, as a functional investigation, we monitored prolactin production and cell proliferation after estradiol and progesterone treatments. We confirmed the presence of all nuclear and membrane estrogen and progesterone receptors in adenomyotic lesions at gene and protein levels. The expression of membrane progesterone receptors α and β (mPRα, mPRβ) as well as estrogen receptor β (ERβ) was upregulated in adenomyosis compared to normal myometrium. Estradiol significantly increased adenomyotic cell proliferation. Progesterone and cAMP upregulated prolactin secretion in adenomyosis in the same pattern as in the normal endometrium. In the present study, we showed the functional link between estradiol action and adenomyotic cell proliferation, as well as progesterone and prolactin production. Our findings provide novel insights into the sex steroid receptor expression pattern and potential regulated pathways in adenomyosis, suggesting that all receptors play an important role in adenomyosis pathophysiology.

Progesterone-induced blocking factor (PIBF) influences the expression of membrane progesterone receptors (mPRs) on peripheral CD4+ T lymphocyte cells in normal fertile females.

Progesterone-induced blocking factor (PIBF) is a protein secreted by lymphocytes exposed to progesterone (P4). P4 and PIBF have immunomodulatory effects on peripheral CD4+ T cells during normal pregnancy. Membrane progesterone receptors (mPRs) may correlate with the immunomodulatory properties of P4 on T cells. Variation in expression of mPRs may influence P4 regulatory performance during pregnancy. On the other hand, PIBF increases in pregnant normal women compared to women who have experienced abortion. The present study aimed to determine whether PIBF, in addition to having a direct influence on the immune system, can affect P4 performance through its effect on mPR expression. Such novel research findings demonstrate the importance of PIBF in the maintenance of pregnancy. Isolated peripheral blood mononuclear cells (PBMCs) from 30 healthy women were stimulated with the mitogen phytohemagglutinin (PHA). Cells were either exposed to various concentrations of PIBF or had no exposure at all in a culture medium at 37°C for 3days. The mean fluorescence intensity (MFI) of mPRα and mPRβ was evaluated using polyclonal and monoclonal antibodies on CD4+ T cells. PIBF was able to significantly increase mPR expression on the surface of peripheral CD4+ T cells (p ≤ 0.05). This study characterized the effects of PIBF on mPR expression on peripheral CD4+ T cells of healthy fertile women. Thus, a decrease in PIBF concentration during abnormal pregnancy can modulate mPR expression and regulatory performance of P4 on T cells. Future research into this issue is likely to open up a new understanding of the etiology of abortion.

Expression of Membrane Progesterone Receptors in Eutopic and Ectopic Endometrium of Women with Endometriosis.

Endometriosis is one of the most frequent gynecological diseases in reproductive age women, but its etiology is not completely understood. Endometriosis is characterized by progesterone resistance, which has been explained in part by a decrease in the expression of the intracellular progesterone receptor in the ectopic endometrium. Progesterone action is also mediated by nongenomic mechanisms via membrane progesterone receptors (mPRs) that belong to the class II members of the progesterone and adipoQ receptor (PAQR) family. The aim of the present study was to evaluate the expression at mRNA and protein levels of mPR members in the eutopic and ectopic endometrium of women with endometriosis. Total RNA and total protein were isolated from control endometrium (17 samples), eutopic endometrium (17 samples), and ectopic endometrium (9 samples). The expression of PAQR7 (mPRα), PAQR8 (mPRβ), and PAQR6 (mPRδ) at mRNA and protein levels was evaluated by RT-qPCR and Western blot, whereas PAQR5 (mPRγ) gene expression was evaluated by RT-qPCR. Statistical analysis between comparable groups was performed using one-way ANOVA followed by Tukey's multiple comparisons test with a confidence interval of 95 %. The analysis of gene expression showed that PAQR7 and PAQR5 expression was lower in both eutopic and ectopic endometrium as compared to the endometrium of women without endometriosis, whereas the expression of PAQR8 and PAQR6 was only reduced in eutopic endometrium. Furthermore, mPRα and mPRβ protein content was decreased in the ectopic endometrium of women with endometriosis. Our results demonstrate a decrease in the expression and protein content of mPRs in eutopic and ectopic endometrium of patients with endometriosis, which could contribute to the progesterone resistance observed in patients with this disease.

Vitamin D3 induces the expression of membrane progesterone receptors (mPRs) on naive CD4+ T lymphocyte cells in women of reproductive age

ObjectiveVitamin D3 and progesterone (P4) both belong to steroid hormones. These hormones have effects on the function of each other in different ways. The immunomodulatory activity of vitamin D3 and P4 and their role in inducing maternal tolerance for fetus have been shown in various studies. The purpose of this study was to evaluate the effect of vitamin D3 on the expression of membrane progesterone receptors (mPRs) on CD4+ T cells. Materials and methodsNaive CD4+ T cells were isolated from peripheral blood of 38 healthy women of childbearing age. After stimulating by anti-CD3 and anti-CD28 monoclonal antibodies (mAb), these cells were exposed to either various concentrations of vitamin D3 or no exposure at all in a culture medium at 37 °C for 3 days. In the final stage, the mean fluorescence intensity (MFI) of mPRα and mPRβ were evaluated using polyclonal and monoclonal antibodies and several gating strategies on CD4+ T cells. ResultsVitamin D3 significantly increased the expression of mPR α and mPR β on the surface of CD4+ T cells (p ≤ 0.05). ConclusionThe present study demonstrated the potential effect of vitamin D3 on increasing the expression of P4 receptors on CD4+ T cells. This study shows a new aspect of correlation between vitamin D3 and P4 that may influence P4 performance. Therefore, our findings suggest that the appropriate level of this vitamin may affect the optimum P4 immunomodulatory activity during pregnancy.

Expression of membrane progesterone receptors (mPRs) in rat peripheral glial cell membranes and their potential role in the modulation of cell migration and protein expression

The role played by progestogens in modulating Schwann cell pathophysiology is well established. Progestogens exert their effects in these cells through both classical genomic and non-genomic mechanisms, the latter mediated by the GABA-A receptor. However, there is evidence that other receptors may be involved. Membrane progesterone receptors (mPRs) are novel 7-transmembrane receptors coupled to G proteins that have been characterized in different tissues and cells, including the central nervous system (CNS). The mPRs were shown to mediate some of progestogens’ neuroprotective effects in the CNS, and to be upregulated in glial cells after traumatic brain injury. Based on this evidence, this paper investigated the possible involvement of mPRs in mediating progestogen actions in S42 Schwann cells. All five mPR isoforms and progesterone receptor membrane component 1 (PGRMC1) were detected in Schwann cells, and were present on the cell membrane. Progesterone and the mPR-specific agonist, Org-OD-02-0 (02) bound to these membranes, indicating the presence of functional mPRs. The mPR agonist 02 rapidly increased cell migration in an in vitro assay, suggesting a putative role of mPRs in the nerve regeneration process. Treatment with pertussis toxin and 8-Br-cAMP blocked 02-induced cell migration, suggesting this progestogen action is mediated by activation of an inhibitory G protein, leading to a decrease in intracellular cAMP levels. In contrast, long-term mPR activation led to increased expression levels of myelin associated glycoprotein (MAG). Taken together, these findings show that mPRs are present and active in Schwann cells and have a role in modulating their physiological processes.

Progesterone effects on lymphocytes may be mediated by membrane progesterone receptors

Luteal cell-induced proliferation of T lymphocytes devoid of the nuclear progesterone receptor (PGR) is inhibited by progesterone. Functional effects of progesterone on bovine lymphocytes and the expression of membrane progesterone receptors (mPRs) alpha (PAQR7), beta (PAQR8), gamma (PAQR5), and progesterone receptor membrane component 1 (PGRMC1) mRNA were analyzed in corpus luteum (CL) and lymphocytes. Progesterone and a cell-impermeable progesterone conjugate caused a dose-dependent decrease in IL2 receptor α-subunit (IL2RA) mRNA and an increase in interleukin 2 (IL2) mRNA concentrations in cultured PBMCs. In luteal tissues, concentrations of PAQR7 and PAQR8 mRNA were lower in CL collected on day 11 compared with day 18, whereas PGRMC1 and PGR mRNA were greater on day 11 than on day 18. The mRNA of all three PAQRs and PGRMC1 were detected in bovine T lymphocytes, but not in B cells/monocytes. Progesterone increased intracellular Ca++ and reduced the phosphorylation of zeta-chain-associated protein kinase 70 (Zap70). A specific, saturable, and single progesterone binding site with a steroid specificity characteristic of mPRs was demonstrated by saturation and competitive binding assays using T lymphocyte membranes, and PAQR7 receptors were localized on the plasma membranes by immunofluorescence. Thus, progesterone induces specific and rapid functional effects on T lymphocytes in the absence of PGR. The mPRs are potential intermediaries of the cell-surface actions of progesterone because they are expressed in lymphocytes, the actions of progesterone are mimicked by a cell-impermeable form of progesterone, and specific, saturable progesterone binding, which is characteristic of mPRs, is present on lymphocyte membranes.

Expression of Membrane Progesterone Receptors (mPR/PAQR) in Ovarian Cancer Cells: Implications for Progesterone-Induced Signaling Events

The high mortality rates associated with ovarian cancer are largely due to a lack of highly effective treatment options for advanced stage disease; a time when initial diagnosis most commonly occurs. Recent evidence suggests that the steroid hormone, progesterone, may possess anti-tumorigenic properties. With the discovery of a new class of membrane-bound progesterone receptors (mPRs) belonging to the progestin and adipoQ receptor (PAQR) gene family in the ovary, there are undefined mechanisms by which progesterone may inhibit tumor progression. Therefore, our goal was to define potential mPR-dependent signaling mechanisms operative in ovarian cancer cells. We detected abundant mPRα (PAQR7), mPRβ (PAQR8), and mPRγ (PAQR5), but not classical nuclear PR (A or B isoforms) mRNA expression and mPRα protein expression in a panel of commonly used ovarian cancer cell lines. In contrast to mPR action in breast cancer cells, progesterone alone failed to induce changes in cyclic adenosine monophosphate (cAMP) levels in ovarian cancer cells. However, progesterone enhanced cAMP production by β(1,2)-adrenergic receptors and increased isoproterenol-induced transcription from a cAMP response element (CRE)-driven reporter gene. Independently of β-adrenergic signaling, we additionally observed activation of both JNK1/2 and p38 MAPK in response to progesterone alone. This finding was supported by the results of a screen for potential mPR gene targets. Progesterone induced a significant increase in transcription of the pro-apoptotic marker BAX, whose activity and expression has been linked to JNK1/2 and p38 signaling. Inhibitors of JNK, but not p38, blocked progesterone-induced BAX expression. Taken together, these observations implicate at least two distinct signaling pathways that may be utilized by mPRs in ovarian cancer cells that exhibit regulatory genomic changes. These studies on mPR signaling in ovarian cancer lay the foundation for future work aimed at understanding how progesterone exerts its anti-tumorigenic effects in the ovary and suggest that pharmacologic activation of mPRs, abundantly expressed in ovarian cancers, may provide a new treatment option for patients with advanced stage disease.

Expression of membrane progesterone receptors on human T lymphocytes and Jurkat cells and activation of G-proteins by progesterone

Although there is significant evidence for progesterone's role as an immunomodulator, nuclear progesterone receptors have not been consistently identified in immune cells. Recently, three new putative membrane progesterone receptors (mPRs), mPRalpha, mPRbeta, and mPRgamma have been described. The objective of this study was to examine whether mPRs are expressed in peripheral blood leukocytes (PBLs) in women of reproductive age, and to further characterize them in T lymphocytes and immortalized T cells (Jurkat cells). Transcripts for mPRalpha and mPRbeta but not mPRgamma, were detected by RT-PCR in PBLs, T lymphocytes, and Jurkat cells. Western blot analysis showed the presence of the mPRalpha and mPRbeta proteins on cell membranes of T lymphocytes and Jurkat cells. Expression of the mPRalpha mRNA was upregulated in the luteal phase of the menstrual cycle in cluster of differentiation (CD)8+, but not in CD4+, T lymphocytes. Radioreceptor assays revealed specific [(3)H]progesterone binding to T- and Jurkat cell membranes (K(d) 4.25 nM) characteristic of steroid membrane receptors. Progesterone activated an inhibitory G-protein (G(i)), suggesting that mPRs are coupled to G(i) in Jurkat cells. These results suggest a potential novel mechanism for progesterone's immunoregulatory function through activation of mPRs.