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Marsters P, Kendall NR, Campbell BK. Pre-translational regulation of luteinizing hormone receptor in follicular somatic cells of cattle. Anim Reprod Sci 2015; 163:63-74. [PMID: 26507944 PMCID: PMC4679792 DOI: 10.1016/j.anireprosci.2015.09.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 09/28/2015] [Accepted: 09/30/2015] [Indexed: 11/29/2022]
Abstract
Differential regulation of LHR in theca cells (TC) and granulosa cells (GC) is important for normal follicular development. Unlike TC, GC only acquire LH-responsiveness during the later stages of antral follicle development. This study tested the hypothesis that differential LH-responsiveness in these two cell types may be due, in part, to shifts in cellular patterns of alternatively spliced LHR mRNA transcripts which may not be obvious from analysis of total LHR gene expression. It also further explored the role of translation inhibition by an LHR binding protein (LHBP), normally associated with the production of endogenous cholesterol. LHR mRNA variation arises as a result of the alternative splicing of two variable deletion sites (VDS) designated 5′ VDS and 3′ VDS, and it was proposed that differences in cell sensitivity to LH may be due in part to variations in the pattern of the mRNA expression of the receptor variants. The outcomes of the present study support a dynamic multi-facetted regulation of LHR during pre-translation. Not only did the ratio between variants change during antral follicle growth and in vitro cell differentiation but also between TC and GC. Regulation could also be linked to LH concentration feedback mechanisms as the absence of LH caused cultured TC to markedly up-regulate amounts of LHR mRNA. In both TC and GC, LHR mRNA was greatly reduced after treatment to block mevalonate production in the de novo cholesterol pathway, adding further support for a regulatory mechanism linked to enriched cellular amounts of mevalonate kinase.
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Affiliation(s)
- P Marsters
- University of Nottingham, Division of Child Health, Obstetrics and Gynaecology, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom.
| | - N R Kendall
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, United Kingdom
| | - B K Campbell
- University of Nottingham, Division of Child Health, Obstetrics and Gynaecology, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom
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Araújo V, Gastal M, Wischral A, Figueiredo J, Gastal E. Long-term in vitro culture of bovine preantral follicles: Effect of base medium and medium replacement methods. Anim Reprod Sci 2015; 161:23-31. [DOI: 10.1016/j.anireprosci.2015.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 07/18/2015] [Accepted: 07/23/2015] [Indexed: 10/23/2022]
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Marsters P, Alhamdan R, Campbell BK. Cell density-mediated pericellular hypoxia and the local dynamic regulation of VEGF-a splice variants in ovine ovarian granulosa cells. Biol Reprod 2014; 91:35. [PMID: 24966396 DOI: 10.1095/biolreprod.113.113068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The primary aims of this study were to utilize a specialized culture system to further elucidate the functional significance of pericellular hypoxia within the granulosa cell (GC) compartment of growing follicles, and to clarify its effects on the production of vascular endothelial growth factor (VEGF)-A isoforms and steroid hormones. Multilaminar clusters formed rapidly in ovine GCs seeded at high density (HD), and Hypoxyprobe-1 protein adducts appeared markedly more abundant and HIF-1 activation significantly (P < 0.001) greater than in cells seeded at low density (LD). Four proangiogenic VEGF mRNA transcript variants were identified in cultured GCs. Most abundant were VEGF120 and VEGF164, but VEGF182 and VEGF188 were also detected. Total VEGF mRNA was shown to be up-regulated transiently in the HD cells (P < 0.001) and VEGF164 mRNA appeared to contribute most to this. The hypoxia mimetic cobalt chloride also induced marked increases in HIF-1 activation (P < 0.01) and total VEGF mRNA (P < 0.01) production. HD cells increased levels of HIF-1alpha (P < 0.001) and VEGF receptor type 1 (P < 0.05), but not VEGF receptor type 2 mRNA, compared to LD cells or cells grown under chemically induced hypoxia. Both 17beta-estradiol (E2) and progesterone (P4) were markedly lower (P < 0.001) in the HD, cells but though cobalt chloride treatment accompanied significantly reduced P4 production (P < 0.05), E2 levels remained similar to those in untreated cells. These outcomes suggest that pericellular hypoxia may be an important mediator of VEGF production in the GCs of growing follicles, but that local regulation is complex and may involve multiple mechanisms such as mediation by steroid hormones and differential variant mRNA production.
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Affiliation(s)
- Peter Marsters
- Division of Human Development, School of Clinical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Rana Alhamdan
- Division of Human Development, School of Clinical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Bruce K Campbell
- Division of Human Development, School of Clinical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
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Aad PY, Echternkamp SE, Spicer LJ. Possible role of IGF2 receptors in regulating selection of 2 dominant follicles in cattle selected for twin ovulations and births. Domest Anim Endocrinol 2013; 45:187-95. [PMID: 24209503 DOI: 10.1016/j.domaniend.2013.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/10/2013] [Accepted: 09/10/2013] [Indexed: 12/18/2022]
Abstract
Abundance of IGF-2 receptor (IGF2R), FSH receptor (FSHR), and LH receptor (LHCGR) mRNA in granulosa cells (GCs) or theca cells (TCs) or both cells as well as estradiol (E2), progesterone (P4), and androstenedione concentrations in follicular fluid were compared in cows genetically selected (Twinner) or not selected (control) for multiple ovulations and twin births. Cows were slaughtered at day 3 to 4 (day 3) and day 5 to 6 (day 5) of an estrous cycle, and ovaries, follicular fluid, GCs, and TCs were collected. The two largest (F1 and F2) E2-active (EA) and E2-inactive (EI) follicles were selected according to their E2-to-P4 ratio and diameter. Androstenedione levels in EA F1 and F2 follicles were 5-fold greater (P < 0.05) in Twinner cows than in control cows on day 3 but did not differ on day 5. Twinner cows also had greater (P < 0.05) E2 and P4 concentrations, whereas steroid levels in EI follicles did not differ (P > 0.10) between genotypes. In EA F2 follicles, IGF2R levels in GCs were greater (P < 0.05) in control cows than in Twinner cows on day 3 and day 5, whereas IGF2R mRNA in TCs did not differ (P > 0.10). On day 3, FSHR mRNA levels were greater (P < 0.05) in GCs of EA F1 and EI F2 follicles of control cows than of Twinner cows. LH receptor mRNA expression was less in GCs and greater in TCs of EA F2 follicles in control cows than in Twinner cows (P < 0.05). We hypothesize that reduced GC IGF2R expression in F2 follicles of Twinner cows may play a role in the development of 2 or more dominant follicles.
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Affiliation(s)
- P Y Aad
- Department of Animal Science, Oklahoma State University, 114 Animal Science Bldg., Stillwater, OK 74078, USA
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Glister C, Satchell L, Knight PG. Granulosal and thecal expression of bone morphogenetic protein- and activin-binding protein mRNA transcripts during bovine follicle development and factors modulating their expression in vitro. Reproduction 2011; 142:581-91. [PMID: 21821720 DOI: 10.1530/rep-11-0150] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Evidence supports local roles for transforming growth factor β superfamily members including activins and bone morphogenetic proteins (BMP) in follicle development. Access of these ligands to signalling receptors is likely modulated by extracellular binding proteins (BP). In this study, we compared ex vivo expression of four BPs (chordin, gremlin, noggin and follistatin) in granulosal (GC) and theca interna (TC) compartments of developing bovine antral follicles (1-18 mm). Effects of FSH and IGF on BMP and BP expression by cultured GC, and effects of LH and BMPs on BP expression by cultured TC were also examined. Follicular expression of all four BP transcripts was higher in GC than TC compartments (P < 0.001) a finding confirmed by immunohistochemistry. Follicle category affected (P < 0.01) gremlin and follistatin mRNA abundance, with a significant cell-type × follicle category interaction for chordin, follistatin and noggin. Noggin transcript abundance was lower (P < 0.05) in GC of large 'E-active' than 'E-inactive' follicles while follistatin mRNA level was higher (P < 0.01). FSH enhanced CYP19, FSHR, INHBA and follistatin by GC without affecting BMP or BMP-BP expression. IGF increased CYP19 and follistatin, reduced BMP4, noggin and gremlin but did not affect chordin or FSHR mRNA levels. LH increased TC androgen secretion but had no effect on BMP or BP expression. BMPs uniformly suppressed TC androgen production whilst increasing chordin, noggin and gremlin mRNA levels up to 20-fold (P < 0.01). These findings support the hypothesis that extracellular BP, mostly from GC, contribute to the regulation of intrafollicular BMP/activin signalling. Enhancement of thecal BP expression by BMP implies an autoregulatory feedback role to prevent excessive signalling.
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Affiliation(s)
- Claire Glister
- School of Biological Sciences, University of Reading, Hopkins Building, Whiteknights, Reading RG6 6UB, UK
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Velazquez MA, Spicer LJ, Wathes DC. The role of endocrine insulin-like growth factor-I (IGF-I) in female bovine reproduction. Domest Anim Endocrinol 2008; 35:325-42. [PMID: 18703307 DOI: 10.1016/j.domaniend.2008.07.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/10/2008] [Accepted: 07/14/2008] [Indexed: 10/21/2022]
Abstract
Insulin-like growth factor-I (IGF-I) plays a pivotal role in cattle fertility, acting as a monitoring signal that allows reproductive events to occur when nutritional conditions for successful reproduction are reached. However, endocrine IGF-I is not a predictor of reproductive events, but rather an indirect estimator of the suitability of the animal to achieve the reproductive event in question. Although measuring circulating IGF-I concentrations might not have any clinical application in the cattle industry, endocrine IGF-I screening will continue to be important for the study of interactions between nutrition and reproduction. In addition, endocrine IGF-I screening could be used as an ancillary test for the selection of cattle for high reproductive potential, especially in herds of high genetic merit for milk production, in which a decline in fertility has been identified.
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Affiliation(s)
- M A Velazquez
- Escuela Superior de Ciencias Agropecuarias, Universidad Autónoma de Campeche, Calle 53 s/n, C.P. 24350, Escárcega, Campeche, Mexico.
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Zheng X, Price CA, Tremblay Y, Lussier JG, Carrière PD. Role of transforming growth factor-β1 in gene expression and activity of estradiol and progesterone-generating enzymes in FSH-stimulated bovine granulosa cells. Reproduction 2008; 136:447-57. [DOI: 10.1530/rep-07-0316] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Survival and inhibitory factors regulate steroidogenesis and determine the fate of developing follicles. The objective of this study was to determine the role of transforming growth factor-β1 (TGFB1) in the regulation of estradiol-17β (E2) and progesterone (P4) secretion in FSH-stimulated bovine granulosa cells. Granulosa cells were obtained from 2 to 5 mm follicles and cultured in serum-free medium. FSH dose (1 and 10 ng/ml for 6 days) and time in culture (2, 4, and 6 days with 1 ng/ml FSH) increased E2secretion and mRNA expression of E2-related enzymes cytochrome P450 aromatase (CYP19A1) and 17β-hydroxysteroid dehydrogenase type 1 (HSD17B1), but notHSD17B7. TGFB1 in the presence of FSH (1 ng/ml) inhibited E2secretion, and decreased mRNA expression of FSH receptor(FSHR),CYP19A1, andHSD17B1, but notHSD17B7. FSH dose did not affect P4secretion and mRNA expression of 3β-hydroxysteroid dehydrogenase (HSD3B) and α-glutathioneS-transferase (GSTA), but inhibited the amount of steroidogenic acute regulatory protein(STAR)mRNA. Conversely, P4and mRNA expression ofSTAR, cytochrome P450 side-chain cleavage(CYP11A1),HSD3B, andGSTAincreased with time in culture. TGFB1 inhibited P4secretion and decreased mRNA expression ofSTAR,CYP11A1,HSD3B, andGSTA. TGFB1 modified the formation of granulosa cell clumps and reduced total cell protein. Finally, TGFB1 decreased conversion of androgens to E2, but did not decrease the conversion of estrone (E1) to E2and pregnenolone to P4. Overall, these results indicate that TGFB1 counteracts stimulation of E2and P4synthesis in granulosa cells by inhibiting key enzymes involved in the conversion of androgens to E2and cholesterol to P4without shutting down HSD17B reducing activity and HSD3B activity.
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Ulloa-Aguirre A, Zariñán T, Pasapera AM, Casas-González P, Dias JA. Multiple facets of follicle-stimulating hormone receptor function. Endocrine 2007; 32:251-63. [PMID: 18246451 DOI: 10.1007/s12020-008-9041-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 01/04/2008] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Follicle-stimulating hormone (FSH) is a glycoprotein hormone produced by the anterior pituitary gland. This gonadotropin plays an essential role in reproduction. Its receptor (FSHR) belongs to the superfamily of G protein-coupled receptors (GPCR), specifically the family of rhodopsin-like receptors. Agonist binding to the FSHR triggers the rapid activation of multiple signaling cascades, mainly the cAMP-adenylyl cyclase-protein kinase A cascade, that impact diverse biological effects of FSH in the gonads. As in other G protein-coupled receptors, the several cytoplasmic domains of the FSHR are involved in signal transduction and termination of the FSH signal. Here we summarize some recent information on the signaling cascades activated by FSH as well as on the role of the intracytoplasmic domains of the FSHR in coupling to membrane and cytosolic proteins linked to key biological functions regulated by the FSH-FSHR system.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia "Luis Castelazo Ayala", Instituto Mexicano del Seguro Social, Apartado Postal 99-065, Unidad Independencia, C.P. 10101 Mexico, D.F., Mexico.
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Webb R, Garnsworthy PC, Campbell BK, Hunter MG. Intra-ovarian regulation of follicular development and oocyte competence in farm animals. Theriogenology 2007; 68 Suppl 1:S22-9. [PMID: 17540442 DOI: 10.1016/j.theriogenology.2007.04.036] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In both mono-ovulatory species, such as cattle, and poly-ovulatory species, such as pigs, the interactions among extra-ovarian gonadotropins, metabolic hormones and intra-ovarian growth factors determine the continued development of follicles, the number of follicles that ovulate and the developmental competence of the ovulated oocyte. FSH and then subsequently LH are the main hormones regulating antral follicle growth in both mono- and poly-ovular species. However, a range of intra-ovarian growth factors, such as insulin-like growth factors (IGFs) and bone morphogenetic proteins (BMPs), are expressed throughout follicle and oocyte development and interact with gonadotropins to control follicle maturation. In addition, environmental factors such as nutrition, including both the amount and composition of the diet consumed prior to ovulation, can influence follicle development and the quality of the oocyte. Recent progress in our understanding has resulted in the development of diets that enhance oocyte quality and improve pregnancy rate in both pigs and cattle. In conclusion, despite some species-specific differences, similar interacting mechanisms control follicular development and influence oocyte quality.
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Affiliation(s)
- R Webb
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
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Campbell BK, Souza CJH, Skinner AJ, Webb R, Baird DT. Enhanced response of granulosa and theca cells from sheep carriers of the FecB mutation in vitro to gonadotropins and bone morphogenic protein-2, -4, and -6. Endocrinology 2006; 147:1608-20. [PMID: 16396991 DOI: 10.1210/en.2005-0604] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The FecB (Booroola) mutation, which leads to increased ovulation rates and multiple births in sheep, is now known to occur in the signaling domain of the bone morphogenic protein (BMP)-1B receptor. We examined the effect of the mutation on the responsiveness of granulosa (GC) and theca cells (TC) to BMPs and other local regulators using tissue from animals with (Fec(B/B)) and without (Fec(+/+)) the FecB mutation. Experiments examined the effect of BMP-2, -4, and -6 (0.005-50 ng/ml), and their interaction with IGF-I (0.1-10 ng/ml LR3 analog) and gonadotropins, on the proliferation and differentiation of GCs and TCs isolated from small (<2 mm) antral follicles and maintained in serum-free culture for up to 8 d. Dose-finding studies using ovaries from wild-type sheep obtained from the abbattoir showed no difference among the different BMPs in stimulating (P < 0.001) estradiol (E2) production by GCs cultured with FSH (10 ng/ml), but there was a clear interaction (P < 0.001) with IGF-I. BMPs had no effect on GC proliferation or the sensitivity of GCs to FSH. In contrast, higher doses of BMPs (5-50 ng/ml) inhibited LH-stimulated androstenedione production by TCs, whereas lower doses (0.005-0.05 ng/ml) stimulated TC proliferation (P < 0.01). Regardless of dose of IGF-I, at the end of culture (96-192 h) hormone production by GCs (E2, inhibin A) and TCs (androstenedione) was 4- to 5-fold greater (P < 0.001) by cells from Fec(B/B), compared with Fec(+/+) ewes exposed to the same dose of gonadotropin. In the presence of low concentrations of IGF-I (0.1 ng/ml), the maximum increase in the production of E2 and inhibin A by GCs from FF ewes in response to BMPs was observed at doses that were 3- to 10-fold lower (3-10 ng/ml) than ++ (30 ng/ml; P < 0.001). Low doses of BMPs stimulated proliferation of TCs from ++ (P < 0.01) but not FF ewes. Immunohistochemistry confirmed BMP-6 protein expression in the oocyte, granulosa, and thecal layers of antral follicles from both genotypes. These results confirm a major role for BMPs in controlling ovarian somatic cell function in sheep and provide evidence to support the hypothesis that the FecB mutation increases the BMP response of somatic cells when stimulated to differentiate by gonadotropins.
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Affiliation(s)
- B K Campbell
- Department of Obstetrics and Gynaecology, Queen's Medical Centre, University of Nottingham, UK.
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Abstract
CONTEXT For the last 40 yr, the first line of treatment for anovulation in infertile women has been clomiphene citrate (CC). CC is a safe, effective oral agent but is known to have relatively common antiestrogenic endometrial and cervical mucous side effects that could prevent pregnancy in the face of successful ovulation. In addition, there is a significant risk of multiple pregnancy with CC, compared with natural cycles. Because of these problems, we proposed the concept of aromatase inhibition as a new method of ovulation induction that could avoid many of the adverse effects of CC. The objective of this review was to describe the different physiological mechanisms of action for CC and aromatase inhibitors (AIs) and compare studies of efficacy for both agents for ovulation induction. EVIDENCE ACQUISITION We conducted a systematic review of all the published studies, both controlled and noncontrolled, comparing CC and AI treatment, either alone or in combination with gonadotropins, for ovulation induction or augmentation, identified through the Entrez-PubMed search engine. EVIDENCE SYNTHESIS Because of the recent acceptance of the concept of using AIs for ovulation induction, few controlled studies were identified, and the rest of the studies were pilot or preliminary comparisons. Based on these studies, it appears that AIs are as effective as CC in inducing ovulation, are devoid of any antiestrogenic side effects, result in lower serum estrogen concentrations, and are associated with good pregnancy rates with a lower incidence of multiple pregnancy than CC. When combined with gonadotropins for assisted reproductive technologies, AIs reduce the dose of FSH required for optimal follicle recruitment and improve the response to FSH in poor responders. CONCLUSIONS Preliminary evidence suggests that AIs may replace CC in the future because of similar efficacy with a reduced side effect profile. Although worldwide experience with AIs for ovulation induction is increasing, at present, definitive studies in the form of randomized controlled trials comparing CC with AIs are lacking.
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Affiliation(s)
- Robert F Casper
- Division of Reproductive Services, Fran and Lawrence Bloomberg Department of Obstetrics and Gynecology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital and The University of Toronto, Toronto, Ontario, Canada M5S 2X9.
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Pasapera AM, Jiménez-Aguilera MDP, Chauchereau A, Milgrom E, Olivares A, Uribe A, Gutiérrez-Sagal R, Ulloa-Aguirre A. Effects of FSH and 17beta-estradiol on the transactivation of estrogen-regulated promoters and cell proliferation in L cells. J Steroid Biochem Mol Biol 2005; 94:289-302. [PMID: 15857748 DOI: 10.1016/j.jsbmb.2004.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Accepted: 11/29/2004] [Indexed: 11/26/2022]
Abstract
In the present study, we analyzed human follicle-stimulating hormone (FSH)-induced cell proliferation and transactivation of estrogen-sensitive reporter genes-in L cells stably expressing the human FSH receptor [L-(hFSHR(+)) cells]. In order to dissect the signaling pathways involved in this process, L-(hFSHR(+)) cells were transiently transfected with either the 3X-ERE-TAT-Luc or the ERE-VitA2-TK-CAT reporter genes and treated with FSH or PKA activators (cholera toxin, forskolin and 8-Br-cAMP) in the presence or absence of various kinase inhibitors. We found that FSH and all PKA activators, specifically induced transactivation of both reporter genes. Transactivation of estrogen-sensitive genes by FSH or PKA activators were blocked (approximately 90%) by H89 (PKA inhibitor) and LY294002 but not by Wortmannin (PI3-K inhibitors), 4-OH-tamoxifen, ICI182,780 or SB203580 (p38 MAPK inhibitor); PD98059 (ERK1/2 inhibitor) partially (approximately 30%) blocked the FSH-mediated effect. The combination of FSH and estradiol resulted in a synergistic effect on transactivation as well as on cell proliferation, and this enhancement was attenuated by antiestrogens. We additionally analyzed the participation of the coactivators SRC-1 and cAMP response element binding protein (CREB)-binding protein (CBP) in FSH-evoked estrogen receptor (ER)-dependent transactivation; we found that CBP but not SRC-1 potentiated FSH-induced transcriptional activation of both ER-sensitive reporters, being this effect stronger on the ERE-VitA2-TK-CAT than on the 3X-ERE-TAT-Luc reporter. Thus, in L-(hFSHR(+)) cells FSH induces transcriptional activation of estrogen-sensitive genes through an A-kinase-triggered signaling pathway, using also to a lesser extent the ERK1/2 and p38 pathways. PI3-K is not apparently involved in this FSH-mediated process since LY294002, but not Wortmannin, specifically binds ERs and completely blocks estrogen action. Presumably, CBP cooperates with the ER on genes that contain estrogen responsive elements through mechanisms involving the participation of other proteins and/or basal transcription factors (e.g. CREB), which in turn mediate the transcriptional response of estrogen-sensitive reporter genes to FSH stimulation.
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Affiliation(s)
- Ana María Pasapera
- Research Unit in Reproductive Medicine, Hospital de Gineco-Obstetricia Luis Castelazo Ayala, Instituto Mexicano del Seguro Social, Apdo. Postal 99-065, Unidad Independencia, México D.F. C.P. 10101, Mexico
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