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Cox KH. A Kiss and a PRomise. Endocrinology 2015; 156:3063-5. [PMID: 26295491 PMCID: PMC4541626 DOI: 10.1210/en.2015-1602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Kimberly H Cox
- Reproductive Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
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Yuen T, Choi SG, Pincas H, Waring DW, Sealfon SC, Turgeon JL. Optimized amplification and single-cell analysis identify GnRH-mediated activation of Rap1b in primary rat gonadotropes. Mol Cell Endocrinol 2012; 350:10-9. [PMID: 22127306 PMCID: PMC3919063 DOI: 10.1016/j.mce.2011.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/15/2011] [Accepted: 11/15/2011] [Indexed: 10/15/2022]
Abstract
Identifying the early gene program induced by GnRH would help understand how GnRH-activated signaling pathways modulate gonadotrope secretory response. We previously analyzed GnRH-induced early genes in LβT2 cells, however these lack GnRH self-potentiation, a physiological attribute of gonadotropes. To minimize cellular heterogeneity, rat primary pituitary cultures were enriched for gonadotropes by 40-60% using a sedimentation gradient. Given the limited number of gonadotropes, RNA was amplified prior to microarray analysis. Thirty-three genes were up-regulated 40 min after GnRH stimulation. Real-time PCR confirmed regulation of several transcripts including fosB, c-fos, egr-2 and rap1b, a small GTPase and member of the Ras family. GnRH stimulated rap1b gene expression in gonadotropes, measured by a sensitive single cell assay. Immunocytochemistry revealed increased Rap1 protein in GnRH-stimulated gonadotropes. These data establish rap1b as a novel gene rapidly induced by GnRH and a candidate to modulate gonadotropin secretion in rat gonadotropes.
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Affiliation(s)
- Tony Yuen
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Soon Gang Choi
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Hanna Pincas
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Dennis W. Waring
- Division of Endocrinology, Department of Internal Medicine, School of Medicine, University of California, Davis, CA 95616, United States
| | - Stuart C. Sealfon
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Judith L. Turgeon
- Division of Endocrinology, Department of Internal Medicine, School of Medicine, University of California, Davis, CA 95616, United States
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Gordon A, Garrido-Gracia JC, Aguilar R, Sánchez-Criado JE. Ovarian stimulation with FSH in the rat reduces proestrous GnRH-dependent LH secretion through a dual mechanism: Inhibition of LH synthesis and release. Neurosci Lett 2009; 460:219-22. [DOI: 10.1016/j.neulet.2009.05.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 04/24/2009] [Accepted: 05/19/2009] [Indexed: 11/27/2022]
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Attardi B, Scott R, Pfaff D, Fink G. Facilitation or inhibition of the oestradiol-induced gonadotrophin surge in the immature female rat by progesterone: effects on pituitary responsiveness to gonadotrophin-releasing hormone (GnRH), GnRH self-priming and pituitary mRNAs for the progesterone receptor A and B isoforms. J Neuroendocrinol 2007; 19:988-1000. [PMID: 18001329 DOI: 10.1111/j.1365-2826.2007.01613.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Progesterone can either facilitate or inhibit the oestradiol (E(2))-induced gonadotrophin surge. We have previously developed immature female rat models to characterise and investigate the mechanisms of progesterone inhibition or facilitation. The aim of the present study was to determine the role of pituitary responsiveness to gonadotrophin-releasing hormone (GnRH) and GnRH self-priming under conditions of progesterone-facilitation and progesterone-inhibition, and whether the underlying mechanisms reflect changes in mRNAs encoding the A and B isoforms of the progesterone receptor (PR) in the pituitary gland. Pituitary responsiveness to GnRH, determined by measuring the luteinising hormone (LH) response to one i.v. injection of GnRH, was decreased by 60-80% (P < 0.001) in the progesterone-inhibition model. GnRH self-priming, estimated as the increment in the LH response to the second of two injections of GnRH separated by 60 min, was also significantly reduced (P < 0.05) in this model. In the progesterone-facilitation model, the LH response to GnRH injection was increased 2.5-3-fold (P < 0.05), an effect suppressed by the progesterone receptor antagonist, mifepristone. Progesterone-facilitation of LH release and increased pituitary responsiveness to GnRH were blocked by sheep anti-GnRH serum injected i.v. immediately after insertion of progesterone implants. The PR-B mRNA isoform, measured by solution hybridisation/RNase protection assay, was the predominant form in the pituitary of the immature female rat. PR-B was increased by E(2) and decreased by progesterone in both models. Thus, in immature female rats, progesterone-inhibition of the E(2)-induced LH surge is due to significant reduction in pituitary responsiveness to GnRH as well as in the magnitude of GnRH self-priming. Progesterone-facilitation of the E(2)-induced LH surge is due to increased pituitary responsiveness to GnRH, which is mediated by PR, and depends on endogenous GnRH release. The differences between progesterone-facilitation and progesterone-inhibition are not due to differences in regulation of pituitary PR-B mRNA.
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Affiliation(s)
- B Attardi
- Department of Neurobiology and Behavior, The Rockefeller University, New York, NY, USA.
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Garrido-Gracia JC, Bellido C, Aguilar R, Sánchez-Criado JE. Protein kinase C cross-talk with gonadotrope progesterone receptor is involved in GnRH-induced LH secretion. J Physiol Biochem 2006; 62:35-42. [PMID: 16909930 DOI: 10.1007/bf03165804] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In the absence of progesterone (P), the anti-P at the receptor RU486 reduces basal and GnRH-stimulated LH secretion both in vivo and in vitro, demonstrating the existence of a ligand-independent activation of progesterone receptor (LIAPR). The aim of the present study was to determine which component of the intracellular LH secretory pathway activated by GnRH is responsible for LIAPR. To do this, anterior pituitary dispersed cells from female rats in proestrus, cultured in the presence of 17beta-estradiol, were incubated with activators or inhibitors of PKC, cAMP-PKA signalling pathways or intracellular calcium (Ca2+) traffic, in the presence or absence of RU486. Results showed that RU486 reduced both GnRH- and the PKC activator PMA-induced LH secretion. In GnRH-stimulated cells incubated with the PKC inhibitor BIS-I or treated with PMA "overnight", RU486 had no effect on reduced LH secretion, nor on stimulated LH secretion elicited by the Ca2+ ionophore ionomycin. Moreover, when GnRH- or PMA-treated cells were co-incubated with 1 microM of the L-type Ca2+ channel blocker nifedipine or the intracellular Ca2+ chelator BAPTA-AM, RU486 potentiated the expected inhibition of these drugs on LH secretion. Activation (forskolin, 8-Br-cAMP) or inhibition (MDL-12,330A) of the cAMP-PKA signalling cascade affected neither the GnRH- and PMA-induced increase of LH secretion nor the reduction of LH secretion due to RU486. Taken together, the data point to the existence of a Ca2+ -independent PKC-PR cross-talk mechanism as part of the intracellular signalling of GnRH-stimulated LH secretion.
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Affiliation(s)
- J C Garrido-Gracia
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Avda. Menéndez Pidal s/n, 14004 Córdoba, Spain.
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Aguilar R, Bellido C, Sánchez-Criado JE. The role of estrogen-dependent progesterone receptor in protein kinase C-mediated LH secretion and GnRH self-priming in rat anterior pituitary glands. J Endocrinol Invest 2003; 26:527-32. [PMID: 12952366 DOI: 10.1007/bf03345215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The aim of the present study was to explore the involvement of pituitary progesterone receptor (PR) in PKC-mediated LH secretion and LHRH self-priming and the role of the estrogen (E) environment. Eight randomly selected hemipituitaries from adult female rats in proestrus or from 2 weeks ovariectomized (OVX) rats were incubated, in the absence of progesterone (P), over 3 h in Dulbecco's modified Eagle's medium (DMEM). In the first experiment, hemipituitaries were incubated continuously with: medium alone, GnRH (10 nM), the PKC stimulator PMA (100 nM), the PKC inhibitor staurosporine (100 nM), the antiprogestin at the receptor RU486 (10 nM), LHRH+staurosporine, GnRH+RU486 or PMA+RU486. In the second experiment, hemipituitaries were incubated, one h apart, with GnRH to determine the GnRH self-priming and this was compared with the priming effect of PMA. Also, the effect of staurosporine and RU486 during the induction period (1st h) on GnRH and PMA priming was evaluated. Medium was aspirated at the end of each h to determine LH accumulation and to evaluate GnRH self-priming. Both GnRH and PMA stimulated LH secretion. Staurosporine and RU486 reduced basal and GnRH-stimulated LH secretion, and RU486 reduced PMA-stimulated LH secretion from proestrus pituitaries. The stimulating effect of GnRH and PMA on LH secretion and the inhibitory action of staurosporine and RU486 on basal or stimulated LH secretion were significantly reduced in OVX-rats. Both GnRH and PMA induced GnRH priming. Staurosporine during the induction h reduced GnRH self-priming while RU486 reduced both GnRH self-potentiation and PMA priming. The magnitude of these inhibitory effects was blunted in OVX-rats. These results showed that PKC signaling pathway in the gonadotrope mediates, at least in part, basal and GnRH-stimulated LH secretion and GnRH self-priming. Also, the results are suggestive of an interaction of PKC signaling pathway with E-dependent PR in a ligand-independent activation manner in the gonadotrope.
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Affiliation(s)
- R Aguilar
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Córdoba, Spain
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Seo HS, Leclercq G. Evaluation of potential implication of membrane estrogen binding sites on ERE-dependent transcriptional activity and intracellular estrogen receptor-alpha regulation in MCF-7 breast cancer cells. J Steroid Biochem Mol Biol 2002; 80:109-23. [PMID: 11867270 DOI: 10.1016/s0960-0760(01)00175-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The potential involvement of membrane estrogen binding sites in the induction of ERE-dependent transcriptional activity as well as in the regulation of intracellular estrogen receptor alpha (ER-alpha) level under estradiol (E2) stimulation was investigated. Our approach relied upon the use of two DCC-treated E2-BSA (bovine serum albumin) solutions (E2-6-BSA and E2-17-BSA). The absence of detectable free E2 in these solutions was established. Both E2-BSA conjugates led to a transient dose-dependent stimulation of the expression of ERE-luciferase (LUC) reporter gene in MVLN cells (MCF-7 cells stably transfected with a pVit-tk-LUC reporter plasmid), a property not recorded with free E2, which maintained enhanced transcriptional activity during the whole experiment. A very low concentration of E2 (10 pM) synergistically acted with E2-BSA conjugates. Hence, ERE-dependent transcriptional activity induced by these conjugates appeared to result from their known interactions with membrane estrogen binding sites. Anti-estrogens (AEs: 4-OH-TAM and RU 58,668), which antagonize genomic ER responses, abrogated the luciferase activity induced by E2-BSA conjugates, confirming a potential relationship between membrane-related signals and intracellular ER. Moreover, induction of luciferase was recorded when the cells were exposed to IBMX (3-isobutyl-1-methylxanthine) and cyclic nucleotides (cAMP/cGMP), suggesting the implication of the latter in the signal transduction pathway leading to the expression of the reporter gene. Growth factors (IGF-I, EGF and TGF-alpha) also slightly stimulated luciferase and synergistically acted with 10 pM E2, or 1 microM E2-BSA conjugates, in agreement with the concept of a cross-talk between steroids and peptides acting on the cell membrane. Remarkably, E2-BSA conjugates, IBMX and all investigated growth factors failed to down-regulate intracellular ER in MCF-7 cells, indicating the need for a direct intracellular interaction of the ligand with the receptor to regulate its level. ER elimination was, however, found in the presence of conditioned media (CMs) prepared from cells pre-exposed to E2-BSA conjugates, suggesting that they may produce (a) modulator(s) that may enhance receptor down-regulation when released within the medium.
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Affiliation(s)
- Hye Sook Seo
- Laboratoire J.-C. Heuson de Cancérologie Mammaire, Service de Médecine Interne, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium
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Turgeon JL, Waring DW. Luteinizing hormone secretion from wild-type and progesterone receptor knockout mouse anterior pituitary cells. Endocrinology 2001; 142:3108-15. [PMID: 11416033 DOI: 10.1210/endo.142.7.8282] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The progesterone receptor (PR) has a central role in the hypothalamo-pituitary events culminating in the preovulatory LH surge, and mice with genetically ablated PR provide a model for dissecting cellular pathways subserving this role. The aims of this study were to determine 1) whether the GnRH self-priming response and acute progesterone augmentation of secretagogue-stimulated LH secretion are present in cultured wild-type (WT) mouse pituitary cells, and 2) whether the PR is essential for self-priming by comparing the responses in PR knockout (PRKO) cells. Pituitary cells from ovariectomized WT or PRKO mice cultured +/- 17beta-estradiol (E(2)) for 3 days were challenged with hourly pulses of 1 nM GnRH or 54 mM K(+). A background of E(2) had no effect on the initial LH secretory response for either WT or PRKO cells. However, for subsequent GnRH pulses, E(2) was permissive for the GnRH self-priming response in WT cells. PRKO cells exhibited a blunted GnRH self-priming response. Exposure to progesterone for 90 min before secretagogue stimulation resulted in a modest (1.5-fold) augmentation of the LH response to GnRH but not K(+) pulses in WT cells; progesterone had no effect in PRKO cells. Unlike in the rat, the PR antagonists RU486 or ZK98299 failed to prevent potentiation of LH secretory responses to multiple GnRH pulses in WT cells. Although RU486 blocked progesterone augmentation of the initial GnRH pulse, it was ineffective in blocking progesterone's action after multiple GnRH pulses. In WT cells, 8- bromo-cAMP (8-Br-cAMP) was able to substitute for the GnRH priming pulse; 8-Br-cAMP also augmented GnRH-stimulated secretion in PRKO cells but less effectively. 8-Br-cAMP augmented K(+)-stimulated LH secretion in WT and PRKO cells equally. These results suggest that, although mouse gonadotropes show GnRH self-priming, they have adapted strategies different than rat cells for amplifying the GnRH signal as shown by the residual self-priming in PRKO cells, the modest or absent augmentation by acute progesterone of GnRH- or K(+)-stimulated secretion in WT cells, and the reduced ability of PR antagonists to interfere with GnRH self-priming and progesterone augmentation. We speculate that the adaptations could involve, at least in part, differences in the ratio of PR isoforms.
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Affiliation(s)
- J L Turgeon
- Department of Human Physiology, School of Medicine, University of California, Davis, Davis, California 95616, USA.
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Levine JE, Chappell PE, Schneider JS, Sleiter NC, Szabo M. Progesterone receptors as neuroendocrine integrators. Front Neuroendocrinol 2001; 22:69-106. [PMID: 11259133 DOI: 10.1006/frne.2001.0210] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intracellular progesterone receptors (PRs) are ligand-inducible transcription factors that mediate the majority of the effects of progesterone (P) on neuroendocrine functions. During the past decade, evidence has accumulated which suggest that PRs can also be activated independently of P, by signals propagated through membrane-bound receptors to the interior of cells. The activation of PRs by this type of "cross-talk" mechanism has been implicated in the physiological regulation of several important neuroendocrine processes, including estrous behavior and periovulatory hormone secretions. We review evidence that both ligand-dependent and ligand-independent activation of PRs occurs in central neurons and in anterior pituitary cells and that the convergence and summation of these signals at the PR serves to integrate neural and endocrine signals which direct several critically important neuroendocrine processes. An integrative function for PRs is reviewed in several physiological contexts, including the display of lordosis behavior in female rodents, the neurosecretion of gonadotropin-releasing hormone surges, secretion of preovulatory gonadotropin surges, and release of periovulatory follicle stimulating hormone surges. The weight of evidence indicates that cross talk at the intracellular PR is an essential component of the integrative mechanisms that direct each of these neuroendocrine events. The recurrence of PR's integrative actions in several different physiological contexts suggests that other intracellular steroid receptors similarly function as integrators of neural and endocrine signals in other neuroendocrine processes.
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Affiliation(s)
- J E Levine
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA.
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Seo HS, Larsimont D, Ma Y, Laios I, Leclercq G. Regulation of estrogen receptor levels by ligand-induced release of compound(s) in MCF-7 cells. Mol Cell Endocrinol 2000; 164:19-29. [PMID: 11026554 DOI: 10.1016/s0303-7207(00)00244-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In MCF-7 cells, estradiol (E2) and pure antiestrogens (AEs) decrease estrogen receptor alpha (ER) levels, while AEs with partial estrogenic activity lead to ER alpha accumulation. Using immunocytochemistry, we found that cells pre-exposed to one of such ligands, when plated with untreated cells, led to similar ER changes in the latter. Conditioned media (CMs) prepared from stimulated cells displayed identical regulatory effects even after strong dilution; they also modulated ERE-dependent transcriptional activity. Evaluation of residual ligand concentrations in CMs rejected the possibility of a major interference of the former. Cycloheximide, which inhibits E2-induced down-regulation, failed to block the influence of CM(E2) in agreement with this view. DCC-treatment of CMs abrogated their effects, suggesting the release of hydrophobic compound(s) which regulate ER and/or amplify the effect of extremely low amounts of residual ligands. Such a release appears independent of ER since CMs from MDA-MB-231 cells (ER-negative) were effective as their autologous media on MCF-7 cells.
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Affiliation(s)
- H S Seo
- Laboratoire J.C. Heuson de Canérologie Mammaire, Service de Médecine Interne, Institut Jules Bordet, Université Libre de Bruxelles, Brussels, Belgium
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Abstract
There are several lines of evidence that point to peptides participating in the regulation of LH and/or FSH levels by action at the pituitary. This evidence includes altered secretion of gonadotropins from the anterior pituitary cells or tissue in vitro when exposed to the peptide. Additionally, modification of GnRH-stimulated LH/FSH secretion has been observed. Furthermore, there is potential for a separately modulated interaction with the primed response. Another potential of action is by interaction among non-GnRH peptides on gonadotropin-regulating processes, although there are no good data available on this aspect. Other observations, consistent with a pituitary role for the peptides in modulation of LH, include detection of the peptides in portal blood, detection of high-affinity receptors or receptor mRNA in the pituitary, and detection of intrapituitary peptide or peptide mRNA in the pituitary. The modulation by steroids of both concentrations and type of activities provides a further level of physiological refinement. There is, however, some confusion regarding the involvement of these peptides in gonadotropin control. The reasons can be seen by considering aspects of investigations. There are experimental variations such as 1) species studied, e.g., NPY has been reported to have an effect on LH secretion from rat cells (168) but not on sheep anterior pituitary tissue (64), and substance P inhibits GnRH-stimulated release from rat cells (182) but potentiates the response in prepubertal porcine cells (92); 2) the steroidal conditions under which the study is performed, e.g., NPY has opposite effects in certain endocrine environments, augmenting GnRH-stimulated LH release in proestrus-like conditions (168), and inhibiting in metestrus-like environment (66); 3) the type of cell preparation, e.g., responsiveness to substance P might depend on whether cells in overnight culture were in separated or clustered state (91); 4) the time course considered, e.g., oxytocin that might induce marked LH release from pituitary cells after a longer length of incubation than GnRH requires (68); 5) length of exposure to peptide, e.g., endothelin that augmented or inhibited GnRH-stimulated LH release (50); 6) In addition, it is possible that the traditional endpoint selected in such studies, namely, observation of gonadotropin secretion, is not necessarily the most important for these peptides (56, 81, 117). Unfortunately, at this stage a definitive answer to the question "What do the peptides actually do?" cannot be provided and we remain tantalized by the glimpses of potential roles. Perhaps in a few years an updated review will be able to include a more complete answer. It is necessary for the full understanding of LH control that not only the properties of the peptides in isolation be characterized but also their interactions.
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Affiliation(s)
- J J Evans
- University Department of Obstetrics and Gynaecology, Christchurch School of Medicine, New Zealand.
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Rauch P, Grebe M, Elke C, Spindler KD, Spindler-Barth M. Ecdysteroid receptor and ultraspiracle from Chironomus tentans (Insecta) are phosphoproteins and are regulated differently by molting hormone. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 1998; 28:265-275. [PMID: 9684334 DOI: 10.1016/s0965-1748(98)00026-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Three different isotypes of the ecdysteroid receptor (cEcR) (66, 68 and 70 kDa) and several molecular variants of the dimerization partner "ultraspiracle" (cUSP) (58-77 kDa) can be separated electrophoretically in homogenates of the epithelial cell line from Chironomus tentans. After phosphatase treatment the bands with the lowest electrophoretic mobility disappear in both cases. Phosphorylation occurs exclusively at ser/thr in EcR and USP. Binding studies with 3H-ponasterone A using 0.4 M NaCl extracts revealed two classes of high-affinity binding (KD1 = 0.47 and KD2 = 7.2 nM) competable either with 20-OH-ecdysone or muristerone A. At least KD2 and Bmax2 are unchanged after dephosphorylation. In hormonally naive cells a considerable part of EcR and USP is already present in nuclei. The phosphorylation pattern of both transcription factors is the same in cytosol and nuclear fractions. Incubation with 20-OH-ecdysone (1 microM, up to 4 days) does not alter the extent and mode of phosphorylation of EcR, although EcR concentration increases. In contrast USP concentration remains constant but phosphorylation is enhanced.
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Affiliation(s)
- P Rauch
- Lehrstuhl für Hormon-u. Entwicklungsphysiologie, Heinrich-Heine-Universität Düsseldorf, Germany
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Honegger J, Renner C, Fahlbusch R, Adams EF. Progesterone receptor gene expression in craniopharyngiomas and evidence for biological activity. Neurosurgery 1997; 41:1359-63; discussion 1363-4. [PMID: 9402587 DOI: 10.1097/00006123-199712000-00022] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVE Previous studies have demonstrated the presence of estrogen receptors in human craniopharyngiomas, raising the possibility that these lesions can be influenced by steroids. To complement these earlier findings, we examined for the presence of progesterone receptor (PR) messenger RNA in surgically removed craniopharyngiomas and performed some studies to determine whether progestogens can exert biological effects on these tumors in vitro. METHODS Total RNA was extracted from fresh surgically removed craniopharyngiomas and reverse-transcribed into cDNA. The polymerase chain reaction was applied to this craniopharyngioma-derived cDNA using amplimers complementary to exons 4 and 7 of the PR gene. Additionally, craniopharyngioma cell cultures were established, and the in vitro effects of progesterone and 6 alpha-methyl-17 alpha-hydroxyprogesterone acetate on [3H]thymidine uptake and 17 beta-estradiol oxidoreductase activity were determined. RESULTS Reversed-transcribed polymerase chain reaction of craniopharyngioma-derived RNA yielded bands of predicted size (389 base pairs) in six of seven tumors studied. Hinfl digestion and direct sequencing of the bands confirmed that the polymerase chain reaction DNA was representative of PR messenger RNA. Treatment of craniopharyngioma cell cultures with progesterone resulted in reduced [3H]thymidine uptake. Both progesterone and 6 alpha-methyl-17 alpha-hydroxyprogesterone acetate powerfully increased oxidative 17 beta-estradiol oxidoreductase activity. CONCLUSION These results provide evidence that PR messenger RNA can be produced by at least some human craniopharyngiomas and indirectly show that this is translated into biologically active receptor protein.
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Affiliation(s)
- J Honegger
- Department of Neurosurgery, University of Erlangen-Nuremberg, Germany
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Maaroufi Y, Ben Hardouze A, Leclercq G. Decrease of hormone binding capacity of estrogen receptor by calcium. J Recept Signal Transduct Res 1997; 17:833-53. [PMID: 9365933 DOI: 10.3109/10799899709039159] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have addressed the question as to whether calcium may modify the [3H]estradiol ([3H]E2) binding properties of the estrogen receptor (ER). A human recombinant full length ER (yER) expressed in yeast was used to limit the potential interference of ER-associated proteins and proteases present in the target tissues. Ca++ (0.1-10 mM) always produced an important loss of [3H]E2 binding capacity without any effect on the hormone binding affinity of residual receptors. This loss was reflected in a decrease of immunoreactivity for monoclonal antibodies raised against the hormone binding domain. An ER recombinant expressing solely this domain confirmed that the ion operated at this level. Binding of [125I]Z-17 alpha-(2-iodovinyl)-11 beta-chloromethyl estradiol-17 beta (an compound with very high selectivity for ER) as well as [125I]tamoxifen aziridine were similarly affected. Size-exclusion chromatography failed to reveal the emergence of any ER isoforms of low molecular weight rejecting the hypothesis of a Ca(++)-induced proteolysis. In agreement with this conclusion, EDTA reversed the loss of [3H]E2 binding capacity. Phosphoamino acids (PY, PT and PS) partly antagonized the effect of Ca++ suggesting its interaction with phosphoamino acid residues. Worthy of note, the effect of Ca++ appeared more marked when assessed by DCC than HAP assay. The phosphocalcic nature of the HAP matrix may explain this phenomenon which was observed with cytosolic ER from various origins.
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Affiliation(s)
- Y Maaroufi
- Laboratoire J.-C. Heuson de Cancérologie Mammaire, Service de Médecine Interne, Institut Jules Bordet, Brussels, Belgium
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Abstract
The results presented underline the fact that the nature and the concentration of the non-esterified fatty acids (NEFAs) liberated from membrane lipids, particularly the essential ones issued from lipid nutrition, clearly belong to a large group of factors (hormones, retinoids, growth factors, cytokines...) which control the shift between cell multiplication and differentiation. NEFAs act on this shift, per se or after being metabolized, by influencing, as second messengers or modulators, the intertwined mechanisms of action of growth factors and steroid hormones. These results may explain the molecular links which exist between endocrinology, oncology and nutrition.
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Affiliation(s)
- E A Nunez
- Laboratoire de Biochimie Endocrinienne, Faculté de Médecine X. Bichat, Université Denis Diderot, Paris, France
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Affiliation(s)
- M J Wheeler
- Department of Chemical Pathology, St Thomas's Hospital, London, UK
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van den Koedijk CD, Blankenstein MA, Thijssen JH. Speculation on the mechanism of action of triphenylethylene antioestrogens. Biochem Pharmacol 1994; 47:1927-37. [PMID: 8010979 DOI: 10.1016/0006-2952(94)90066-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Newton CJ, Buric R, Trapp T, Brockmeier S, Pagotto U, Stalla GK. The unliganded estrogen receptor (ER) transduces growth factor signals. J Steroid Biochem Mol Biol 1994; 48:481-6. [PMID: 8180109 DOI: 10.1016/0960-0760(94)90197-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the absence of serum and estrogen, we show that the growth of the prolactin secreting pituitary tumour cell line, GH3 is stimulated by insulin and insulin-like growth factor-1 (IGF-1) and this response is blocked by the steroidal antiestrogens, ICI 164384 and ICI 182780. From conditioned medium (CM) experiments, growth of low density cells (10k/cm2) is increased by the addition of CM from high density cells (100k/cm2) and this growth effect is also blocked by antiestrogen. Transfection studies with a delta MTV-ERE-LUC reporter plasmid show that in the absence of estrogen and serum, both insulin and IGF-1 induce luciferase expression and this is blocked by the pure antiestrogens. No effect of these treatments was apparent when parallel experiments were conducted with a plasmid construct lacking the vitellogenin estrogen response element. From these and other data discussed in this report, we conclude that for GH3 cells, in the absence of estrogen and serum, the ER is transcriptionally activated by intracellular peptide factor pathways and by this means, acts as the key nuclear factor inducing mitogenesis in response to autocrine and exogenously added growth factors.
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Affiliation(s)
- C J Newton
- Max-Planck-Institute of Psychiatry, Clinical Institute, Munich, Germany
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Van de Velde P, Nique F, Bouchoux F, Brémaud J, Hameau MC, Lucas D, Moratille C, Viet S, Philibert D, Teutsch G. RU 58,668, a new pure antiestrogen inducing a regression of human mammary carcinoma implanted in nude mice. J Steroid Biochem Mol Biol 1994; 48:187-96. [PMID: 8142294 DOI: 10.1016/0960-0760(94)90144-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
RU 58,668, a new steroidal antiestrogen, has been synthesized. Its in vitro and in vivo pharmacological activities have been compared to those of tamoxifen and ICI 182,780. In vitro, it displayed affinities for human and murine estrogen receptors equivalent to those of 4-hydroxy-tamoxifen, along with moderate affinities for progestin and glucocorticoid receptors. RU 58,668 proved to be a potent antiproliferative agent on MCF-7 cells stimulated by estradiol, or by exogenous or endogenous growth factors (IC50, 0.01 nM). It also inhibited the growth of the insulin-stimulated T47D cell line. In vivo, RU 58,668 displayed a total anti-uterotrophic activity in mice or rats without exhibiting any agonistic effect. Moreover, RU 58,668 was the only antiestrogenic compound tested so far to be able to induce a long term regression of human mammary MCF-7 tumors implanted in nude mice, suggesting its potential use for the treatment of advanced breast cancer.
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Abstract
In transient co-transfection assays, there is extensive cross-interaction between glucocorticoid receptor (GR) domains. For example, mutation of the conserved Ile residue at position 484 (rat GR map) to cysteine allows a net separation of transactivation and DNA binding. We also observed that the ligand binding domain plays a key role in cooperative transactivation. Furthermore, some carboxy-located mutations markedly alter the response of GR to agonists and antagonists. Finally, different reading frames of the CAG repeat that normally produces an amino-located poly-Gln repeat profoundly affect GR transactivation without altering DNA or ligand binding. This trans-dominant negative phenotype, seen when the CAG repeat yields a poly-Ala stretch, may turn out to be an excellent tool for functional analysis of GR in transgenic organisms.
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Affiliation(s)
- R B Lanz
- Institüt für Molekularbiologie II der Universität Zürich, Switzerland
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Receptor Regulation. Mol Endocrinol 1994. [DOI: 10.1016/b978-0-12-111231-8.50012-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] Open
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