scholarly journals The role of IGFs in the regulation of ovarian follicular growth in the brushtail possum (Trichosurus vulpecula)

Reproduction ◽  
2010 ◽  
Vol 140 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Jennifer L Juengel ◽  
Lisa J Haydon ◽  
Brigitta Mester ◽  
Brian P Thomson ◽  
Michael Beaumont ◽  
...  

IGFs are known to be key regulators of ovarian follicular growth in eutherian mammals, but little is known regarding their role in marsupials. To better understand the potential role of IGFs in the regulation of follicular growth in marsupials, expression of mRNAs encoding IGF1, IGF2, IGF1R, IGF-binding protein 2 (IGFBP2), IGFBP4 and IGFBP5 was localized by in situ hybridization in developing ovarian follicles of the brushtail possum. In addition, the effects of IGF1 and IGF2 on granulosa cell function were tested in vitro. Both granulosa and theca cells synthesize IGF mRNAs, with the theca expressing IGF1 mRNA and granulosa cell expressing IGF2 mRNA. Oocytes and granulosa cells express IGF1R. Granulosa and theca cells expressed IGFBP mRNAs, although the pattern of expression differed between the BPs. IGFBP5 mRNA was differentially expressed as the follicles developed with granulosa cells of antral follicles no longer expressing IGFBP5 mRNA, suggesting an increased IGF bioavailability in the antral follicle. The IGFBP protease, PAPPA mRNA, was also expressed in granulosa cells of growing follicles. Both IGF1 and IGF2 stimulated thymidine incorporation but had no effect on progesterone production. Thus, IGF may be an important regulator of ovarian follicular development in marsupials as has been shown in eutherian mammals.

Reproduction ◽  
2007 ◽  
Vol 134 (2) ◽  
pp. 293-306 ◽  
Author(s):  
Sara L Al-Musawi ◽  
Richard T Gladwell ◽  
Philip G Knight

The aims were to examine ovarian expression of bone morphogenetic protein (BMP) ligands/receptor mRNAs in the chicken and to test the hypothesis that theca-derived BMP(s) modulates granulosa cell function in a paracrine manner. RT-PCR revealed expression of multiple BMPs in granulosa and theca cells from prehierarchical and preovulatory follicles with greater expression in theca cells; both cell types expressed BMP receptors-IA, -IB and -II consistent with tissue responsiveness. Preovulatory granulosa cells (F1, F2 and F3/4) were cultured with BMP-6 (expressed by theca but not granulosa) in the presence/absence of LH, FSH or 8-Br-cAMP. BMP-6 increased ‘basal’ and gonadotrophin-induced inhibin-A and progesterone secretion by each cell type but did not enhance the effect of 8-Br-cAMP. This indicates that the observed synergism between BMP-6 and gonadotrophin might involve BMP-induced up-regulation of gonadotrophin receptors. In support of this, BMP-6 alone increased LH-receptor (LHR) mRNA in F1 cells and FSH-receptor (FSHR) mRNA in F1, F2 and F3/4 cells. BMP-6 also enhanced LH/FSH-induced LHR transcript amount in each cell type but did not raise FSHR transcript amounts above those induced by BMP-6 alone. To further explore BMP-6 action on inhibin-A secretion, we quantified inhibin/activin subunits (α, βA, βB) mRNAs. Consistent with its effect on inhibin-A secretion, BMP-6 enhanced ‘basal’ expression of α- and βA-subunit mRNA in F1, F2 and F3/4 cells, and βB-subunit mRNA in F3/4 cells. BMP-6 markedly enhanced FSH/LH-induced expression of α-subunit in all follicles and FSH-induced βA-subunit in F2 and F3/4 follicles but not in F1 follicles. Neither BMP-6 alone, nor FSH/LH alone, affected ‘basal’ βB mRNA abundance. However, co-treatment with gonadotrophin and BMP-6 greatly increased βB-subunit expression, the response being lowest in F1 follicles and greatest in F3/4 follicles. Collectively, these results support the hypothesis that intraovarian BMPs of thecal origin have a paracrine role in modulating granulosa cell function in the chicken in a preovulatory stage-dependent manner.


Reproduction ◽  
2013 ◽  
Vol 146 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Yang Gao ◽  
Haixia Wen ◽  
Chao Wang ◽  
Qinglei Li

Transforming growth factor β (TGFβ) superfamily signaling is essential for female reproduction. Dysregulation of the TGFβ signaling pathway can cause reproductive diseases. SMA and MAD (mothers against decapentaplegic) (SMAD) proteins are downstream signaling transducers of the TGFβ superfamily. SMAD7 is an inhibitory SMAD that regulates TGFβ signalingin vitro. However, the function of SMAD7 in the ovary remains poorly defined. To determine the signaling preference and potential role of SMAD7 in the ovary, we herein examined the expression, regulation, and function of SMAD7 in mouse granulosa cells. We showed that SMAD7 was expressed in granulosa cells and subject to regulation by intraovarian growth factors from the TGFβ superfamily. TGFB1 (TGFβ1), bone morphogenetic protein 4, and oocyte-derived growth differentiation factor 9 (GDF9) were capable of inducingSmad7expression, suggesting a modulatory role of SMAD7 in a negative feedback loop. Using a small interfering RNA approach, we further demonstrated that SMAD7 was a negative regulator of TGFB1. Moreover, we revealed a link between SMAD7 and GDF9-mediated oocyte paracrine signaling, an essential component of oocyte–granulosa cell communication and folliculogenesis. Collectively, our results suggest that SMAD7 may function during follicular development via preferentially antagonizing and/or fine-tuning essential TGFβ superfamily signaling, which is involved in the regulation of oocyte–somatic cell interaction and granulosa cell function.


2011 ◽  
Vol 23 (1) ◽  
pp. 32 ◽  
Author(s):  
J. Buratini ◽  
C. A. Price

Considerable attention is currently paid to oocyte-derived secreted factors that act upon cumulus and granulosa cells. Also important for follicle development are somatic cell-derived secreted factors. This is illustrated by the ability of granulosa cell-derived Kit ligand (KITL) to promote primordial follicle activation, and the loss of follicle development that accompanies KITL gene disruption. This review summarises our current understanding of somatic cell factors during both preantral and antral follicle growth, involving not only signalling from granulosa cells to the oocyte, but also signalling between granulosa and theca cells. Principal granulosa cell-derived factors include activin, anti-Müllerian hormone (AMH), bone morphogenetic proteins (BMPs) and fibroblast growth factors (FGFs). Theca cells also secrete BMPs and FGFs. The interplay between these factors is equally important for follicle growth as the activity of oocyte-derived factors.


2005 ◽  
Vol 17 (9) ◽  
pp. 104
Author(s):  
B. Mester ◽  
B. P. Thomson ◽  
D. C. Eckery

The number and size of follicles selected for ovulation differ between species. The aim of this study was to characterise antral follicular growth and determine the size when selection of the ovulatory follicle occurs in the monovular brushtail possum. For this study, antral follicles ≥ 1 mm were dissected from the ovaries of 31 adult female possums at different reproductive states and follicular fluid and granulosa cells were harvested from each individual follicle. Selection of the ovulatory follicle in the brushtail possum occurred when follicles reached between 2.5 and 2.8 mm in diameter. Based on the analysis of steroids in follicular fluid, before selection, most follicles produced varying amounts of oestradiol (E2), but very few if any produced progesterone (P4). After selection, the selected follicle continued to produce increasing amounts of E2 and P4, whereas most other follicles were steroidogenically inactive. Near the time of ovulation, presumably after the LH surge, P4 became the predominant steroid produced by the selected follicle and most other follicles once again produced varying amounts of E2. The number of granulosa cells per follicle was highly variable, but tended to increase with increasing diameter. Cell viability was very high, averaging about 95%. Interestingly, the morphology of granulosa cells changed markedly after selection becoming larger and granular in appearance. The weights of the vaginal cul-de-sac and uteri correlated well with the presence of a selected follicle. In ovaries from pregnant animals (n = 3), follicles grew up to 3.5 mm, and although they reached the size of a selected follicle during the follicular phase, E2 production by the other follicles was not suppressed and the weights of the cul-de-sac were less than those from non-pregnant animals with similar sized follicles. During anoestrus (n = 4), follicles did not grow beyond 2 mm and produced very little steroids.


Endocrinology ◽  
1999 ◽  
Vol 140 (6) ◽  
pp. 2641-2644 ◽  
Author(s):  
Rodolfo Robles ◽  
Xiao-Jing Tao ◽  
Alexander M. Trbovich ◽  
Daniel V. Maravei ◽  
Ravit Nahum ◽  
...  

Abstract The recent characterization of apoptotic protease-activating factor-1 (Apaf-1) in vertebrates as a putative homolog of the Caenorhabditis elegans gene, ced-4, indicates that the third major arm of the C. elegans programmed cell death machinery has also been conserved through evolution. Although apoptosis is now known to be important for ovarian follicular atresia in vertebrates, nothing is known of the role of Apaf-1 in ovarian function. Herein we show by immunohistochemical analysis that Apaf-1 is abundant in granulosa cells of early antral follicles whereas in vivo gonadotropin priming completely suppresses Apaf-1 expression and granulosa cell apoptosis. Western blot analysis of fractionated protein extracts prepared from granulosa cells before and after in vitro culture without hormonal support to induce apoptosis indicated that mitochondrial cytochrome c release, a biochemical step required for the activation of Apaf-1, occurs in granulosa cells cultured in vitro. Moreover, Western blot analysis of procaspase-3 processing, a principal downstream event set in motion by activated Apaf-1, indicated that healthy granulosa cells possess almost exclusively the inactive (pro-) form of the enzyme whereas granulosa cells deprived of hormonal support rapidly process procaspase-3 to the active enzyme. Lastly, we show that serum-starved granulosa cells activate caspase-3-like enzymes both prior to and after nuclear pyknosis, as revealed by a single-cell fluorescent caspase activity assay. These data, combined with previous observations regarding the role of homologs of the two other C. elegans cell death regulatory genes, ced-9 (Bc1-2 family members) and ced-3 (caspases), in atresia fully support the hypothesis that granulosa cell apoptosis is precisely coordinated by all three major arms of a cell death program conserved through evolution.


Reproduction ◽  
2003 ◽  
pp. 709-716 ◽  
Author(s):  
G Maillet ◽  
A Benhaim ◽  
H Mittre ◽  
C Feral

Follicular atresia is characterized by a rapid loss of granulosa cells and, to a lesser extent, theca cells, via apoptosis. The aim of this study was to investigate the possible involvement of theca cell secretions in the regulation of apoptosis of rabbit granulosa cells. The annexin-V binding method based on externalization of phosphatidylserine to the outer layer of plasma membrane during apoptosis was used to detect apoptotic granulosa cells in flow cytometry. Regulation of apoptosis of granulosa cells was studied in three different culture systems: (i) isolated cultured granulosa cells, (ii) granulosa cells obtained from cultured preovulatory follicles and (iii) granulosa cells co-cultured with theca cells. The results of this study indicate that: (i) the rate of apoptosis of granulosa cells was significantly reduced when granulosa cells were co-cultured with theca cells or obtained from cultured preovulatory follicles in comparison with isolated cultured granulosa cells; (ii) FSH exerts its anti-apoptotic effect only on granulosa cells issued from cultured preovulatory follicles; (iii) ovarian steroids do not affect the percentage of isolated apoptotic granulosa cells; and (iv) the occurrence of an apoptotic process in rabbit theca cells could be upregulated in vitro by hCG and an analogue of the gonadotrophin second messenger cAMP. The results of this study indicate that in rabbits (i) steroids were ineffective in vitro in protecting isolated granulosa cells against apoptosis in comparison with observations in vivo in rats, and (ii) the presence of theca cells was efficient to reduce granulosa cell apoptosis but not sufficient to allow the anti-apoptotic effect of gonadotrophins observed in cultured follicles.


1995 ◽  
Vol 145 (3) ◽  
pp. 491-500 ◽  
Author(s):  
J H M Wrathall ◽  
P G Knight

Abstract Primary monolayer cultures of bovine theca cells isolated from pooled ovarian follicles (3–10 mm diameter) were used to examine the effects of various granulosa cell-derived substances on basal and luteinizing hormone (LH)-induced androgen and progesterone secretion. After an overnight pretreatment period, cells were incubated with a range of treatments including LH, oestradiol-17β, inhibin, activin and follistatin. Media were collected after 48 h and assessment of androstenedione and progesterone secretion made by radioimmunoassay. Addition of LH (5–50 ng/ml) to the cells resulted in a dose-dependent stimulation of both androstenedione (2·5-to 3-fold rise; P<0·01) and progesterone (∼ 1·6-fold rise; P<0·001) production. Secretion of androstenedione was also raised (up to 5-fold; P<0·001) by addition of oestradiol-17β (0·3–300 ng/ml), whilst levels of the androgen in the presence of both LH (20 ng/ml) and oestradiol (300 ng/ml) were up to 12-fold higher (P<0·001) than control values. In contrast, oestradiol treatment inhibited by up to 50% both basal (P<0·001) and LH-stimulated (P<0·001) secretion of progesterone. Exposure of cells to purified bovine inhibin (5–125 ng/ml) consistently raised androstenedione secretion by up to 42% over basal levels (P<0·001). Inhibin also enhanced both LH-stimulated (∼20%; P<0·001) and oestradiol-stimulated (∼20%; P<0·05) secretion of androstenedione. In direct contrast, treatment of theca cells with human recombinant activin-A (1–50 ng/ml) inhibited both LH-stimulated (∼50%; P<0·001) and oestradiol-stimulated (∼30%; P<0·005) androstenedione secretion. Activin also reversed the positive effect of inhibin on basal (P<0·01), LH-stimulated (P<0·001) and oestradiol-stimulated (P<0·001) androstenedione secretion, though activin alone did not affect basal steroid output. Simultaneous addition of human recombinant follistatin reversed the inhibitory effects of activin on LH- and oestradiol-induced androstenedione secretion but did not modify the effects of inhibin. Follistatin alone did not alter either basal or LH-stimulated androstenedione output. Neither basal nor LH-stimulated secretion of progesterone were consistently affected by inhibin, activin or follistatin. As well as confirming the stimulatory effects of both LH and oestradiol on bovine thecal cell androgen production, these observations are indicative of opposing intrafollicular paracrine roles for granulosa cell-derived inhibin and activin in modulating thecal cell responses to gonadotrophins and steroids in the bovine ovary. Though inhibin and oestradiol had qualitatively similar effects in promoting thecal androgen secretion, the magnitude of the response to oestradiol was much greater. The results also support an intrafollicular role of follistatin as a binding protein capable of neutralizing the effect of activin, but not inhibin, on thecal androgen production. Journal of Endocrinology (1995) 145, 491–500


Author(s):  
Kenichiro Sakaguchi ◽  
Yojiro Yanagawa ◽  
Koji Yoshioka ◽  
Tomoko Suda ◽  
Seiji Katagiri ◽  
...  

Abstract Background The antral follicle count (AFC) in mammalian ovaries positively correlates with female fertility. To clarify the causes of differences in fertility between low and high AFC cows, we investigated follicular growth dynamics and hormone concentrations in plasma, follicular fluid, and in vitro growth (IVG) media at different stages of follicular growth. Methods Seven cows were divided into high AFC (n = 4, > 30 follicles) and low AFC (n = 3, < 30 follicles) groups based on the peak AFC detected by ultrasonography. These cows were subjected to estrous synchronization, daily ovarian ultrasonography, and blood collection. Their follicular fluid was collected from dominant follicles at different stages (selection, luteal, and ovulatory phases). In another experiment, we cultured oocyte-cumulus-granulosa cell complexes collected from early antral follicles (< 1 mm) for 12 days. Estradiol-17β (E2), testosterone (T), progesterone (P4), and anti-Müllerian hormone (AMH) concentrations in follicular fluids and plasma were measured. Plasma follicle-stimulating hormone (FSH) concentrations were examined. E2, P4, and AMH concentrations were also measured in IVG media. Results The numbers of small (< 4 mm) and intermediate (4–8 mm) follicles were larger in the high AFC group than in the low AFC group (P < 0.05). The number of intermediate follicles was stable in the low AFC group, indicating consistent development. However, the number of these follicles fluctuated in the high AFC group. Plasma FSH concentrations were higher, whereas E2 and T concentrations were lower in the low AFC group (P < 0.05). E2 concentrations and the E2/P4 ratio in ovulatory follicles and IVG media on day 8 were higher in the high AFC group (P < 0.05). AMH concentrations in plasma and IVG media (P < 0.01) were higher in the high AFC group. Conclusions The weaker response to FSH of granulosa cells caused low E2 production in the low AFC group, resulting in high FSH concentrations and the consistent development of intermediate follicles. Conversely, higher E2 concentrations suppressed FSH secretion in the high AFC group. Granulosa cells in the high AFC group had the ability to produce more AMH than those in the low AFC group throughout IVG culture.


Endocrinology ◽  
2021 ◽  
Author(s):  
Pavine L C Lefèvre ◽  
Thomas C Nardelli ◽  
Weon-Young Son ◽  
Amy R Sadler ◽  
Dorothea F K Rawn ◽  
...  

Abstract Polybrominated diphenyl ethers (PBDEs), a major class of flame retardants incorporated into numerous consumer products, leach out into dust resulting in widespread exposure. There is evidence from in vitro and in vivo animal studies that PBDEs affect ovarian granulosa cell function and follicular development, yet human studies of their association with female infertility are inconclusive. Here, we tested the hypothesis that exposure to the PBDEs in follicular fluid is associated with dysregulation of gene expression in the mural and cumulus granulosa cells collected from women undergoing in vitro fertilization by intracytoplasmic sperm injection. The median concentration of the ∑10PBDEs detected in the follicular fluid samples (n=37) was 15.04 pg/g wet weight. RNA microarray analyses revealed that many genes were differentially expressed in mural and cumulus granulosa cells. Highest vs. lowest quartile exposure to the Σ10PBDEs or to two predominant PBDE congeners, BDE-47 or BDE-153, was associated with significant effects on gene expression in both cell types. Mural granulosa cells were generally more sensitive to PBDE exposure compared to cumulus cells. Overall, gene expression changes associated with BDE-47 exposure were similar to those for ∑10PBDEs but distinct from those associated with BDE-153 exposure. Interestingly, exposure to BDE-47 and ∑10PBDEs activated the expression of genes in pathways that are important in innate immunity and inflammation. To the best of our knowledge, this is the first demonstration that exposure to these environmental chemicals is associated with the dysregulation of pathways that play an essential role in ovulation.


2020 ◽  
Vol 27 (10) ◽  
pp. 2856-2871 ◽  
Author(s):  
Marie-Cécile De Cian ◽  
Elodie P. Gregoire ◽  
Morgane Le Rolle ◽  
Simon Lachambre ◽  
Magali Mondin ◽  
...  

Abstract R-spondin2 (RSPO2) is a member of the R-spondin family, which are secreted activators of the WNT/β-catenin (CTNNB1) signaling pathway. In the mouse postnatal ovary, WNT/CTNNB1 signaling is active in the oocyte and in the neighboring supporting cells, the granulosa cells. Although the role of Rspo2 has been previously studied using in vitro experiments, the results are conflicting and the in vivo ovarian function of Rspo2 remains unclear. In the present study, we found that RSPO2/Rspo2 expression is restricted to the oocyte of developing follicles in both human and mouse ovaries from the beginning of the follicular growth. In mice, genetic deletion of Rspo2 does not impair oocyte growth, but instead prevents cell cycle progression of neighboring granulosa cells, thus resulting in an arrest of follicular growth. We further show this cell cycle arrest to be independent of growth promoting GDF9 signaling, but rather associated with a downregulation of WNT/CTNNB1 signaling in granulosa cells. To confirm the contribution of WNT/CTNNB1 signaling in granulosa cell proliferation, we induced cell type specific deletion of Ctnnb1 postnatally. Strikingly, follicles lacking Ctnnb1 failed to develop beyond the primary stage. These results show that RSPO2 acts in a paracrine manner to sustain granulosa cell proliferation in early developing follicles. Taken together, our data demonstrate that the activation of WNT/CTNNB1 signaling by RSPO2 is essential for oocyte-granulosa cell interactions that drive maturation of the ovarian follicles and eventually female fertility.


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