| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Articles |
a Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Stanford, California 94305-5317
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Throughout early antral follicular development in rodents, granulosa cells acquire functional characteristics including the induction of steroidogenic enzymes and LH receptors [8,9]. It is well accepted that these changes are controlled primarily by pituitary-derived FSH [5,6]. However, granulosa cell proliferation and differentiation could also be influenced by oocyte factors, because granulosa cells in fully grown antral follicles display distinct phenotypes in relation to their distance from the oocyte [10,11]. When compared with the mural granulosa cells located farther from the oocyte, the closer cumulus granulosa cells have lower steroidogenic capacity and LH receptor content [12–15].
The existence of oocyte factors responsible for the distinct characteristics of cumulus and mural granulosa cells has been substantiated in studies using cocultures of oocyte and granulosa/cumulus cells. It has been shown that oocyte factors promote the proliferation of granulosa cells [16] but inhibit the FSH stimulation of steroidogenesis [17] and LH receptor formation in granulosa cells [18]. In addition, oocyte factors enable FSH-induced cumulus expansion [19]. However, the exact nature of the oocyte factor(s) responsible for these diverse phenotypes is not known.
Growth differentiation factor-9 (GDF-9) is a protein of the transforming growth factor (TGF-ß)/activin family secreted by the oocyte [20,21,22], and animals deficient in GDF-9 show an arrest of follicle development beyond the primary stage [23]. To date GDF-9 expression has been described in oocytes from rodent [20,22], bovine/ovine [24], and human [25] follicles at early stages of follicular development, indicating its importance in the regulation of folliculogenesis in several species.
Using recombinant GDF-9 proteins and in vitro culture systems [26], we found that GDF-9 treatment enhances preantral follicle growth and stimulates ovarian inhibin-
content in rats [22]. In addition, a recent study showed that treatment with recombinant GDF-9 enables cumulus expansion and reduces LH receptor mRNA in cultured mouse granulosa cells [27]. Because GDF-9 immunostaining can be detected in oocytes from follicles at advanced developmental stages [22], we tested the effect of treatment with GDF-9 on cultured granulosa cells obtained from small antral and preovulatory follicles. Here, we show that GDF-9 treatment promotes granulosa cell proliferation in vitro but antagonizes the FSH induction of steroidogenesis and LH receptor formation in these cells.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Immature female rats (Sprague-Dawley) were obtained from Simonsen Laboratories (Gilroy, CA). Animals (25 days old, body weight from 53 to 68 g) were anesthetized and killed using CO2 either 48 h after treatment with 5 IU eCG (2740 IU/mg, 367222; Calbiochem-Novabiochem, La Jolla, CA) or 72 h after insertion of diethylstilbestrol implants [28]. All animals were housed under controlled humidity, temperature, and light regimen and fed ad libitum on a standard rat chow. Animal care was consistent with institutional and NIH guidelines.
Reagents and Hormones
McCoy's 5a medium (modified) was obtained from Cellgro (Mediatech, Herndon, VA); L-15 Leibovitz medium and Dulbecco's modified Eagle's medium-F12 were obtained from Life Technologies (Gaithersburg, MD). Recombinant human FSH (Org 32489E) was a gift from Dr. Marcel van Duin (Organon NV, The Netherlands). Androstenedione, 3-isobutyl-1-methylxanthine, forskolin, and BSA were obtained from Sigma Chemical Co. (St. Louis, MO); L-glutamine, penicillin, and streptomycin were purchased from BioWhittaker (Wakersville, MD).
Recombinant GDF-9 was generated in transfected mammalian cells and characterized as previously described [22]. Briefly, expression vectors for wild-type and epitope-tagged GDF-9 were constructed using pcDNA3.1 Zeo (Invitrogen, San Diego, CA). N-terminal-tagged GDF-9 encoded a Flag epitope for M1 antibody followed by six histidine residues fused to the amino-terminus of mature GDF-9. In our previous study, N-tagged GDF-9 showed no biological activity and served as a negative control. Human embryonic kidney 293T cells were transfected with the expression vector, and clonal cell lines stably expressing wild-type and tagged GDF-9 were selected under 1 mg/ml of Zeocin (Invitrogen). Conditioned media were harvested after 4 days of serum-free culture. Quantitation of N-tagged GDF-9 was done after purification with nickel column and measurement of protein content using Micro BCA protein assay kit (Perstorp Life Science, Rockford, IL). Purified N-tagged GDF-9 was then used as a standard for the quantitation of wild-type GDF-9 in the conditioned medium of 293T cells by immunoblots using specific GDF-9 antibodies.
Preparation and Culture of Granulosa Cells
Granulosa cells were obtained either from preovulatory follicles of eCG-treated rats or from small antral follicles of diethylstilbestrol-treated rats. Ovaries were punctured in L-15 Leibovitz medium supplemented with 0.1% BSA. Ovarian debris, oocytes, and small follicles were removed, and the remaining medium containing granulosa cells was collected after low-speed centrifugation at 500 x g for 10 min. Granulosa cells were dispersed by repeated washing and suspension into the culture medium (McCoy's 5a supplemented with 10-7 M androstenedione, 0.25 mM 3-isobutyl-1-methylxanthine [a phosphodiesterase inhibitor], 2 mM L-glutamine, 100 U/ml penicillin, and 100 µg/ml streptomycin).
Thymidine Incorporation into Granulosa Cells
Granulosa cells (2 x 105 viable cells/500 µl) were cultured in 5 ml polypropylene Falcon tubes (Becton Dickinson, Franklin Lakes, NJ) with or without increasing concentrations (3, 10, 30, 100, and 150 ng/ml) of GDF-9, N-tagged GDF-9, or FSH (0.5, 5, and 50 ng/ml). Cultures were maintained at 37°C under 5% CO2 in air. To assess nonspecific effects of the conditioned medium from 293T cells, additional negative control groups were incubated with equivalent volumes of conditioned medium from nontransfected 293T cells. For thymidine incorporation trials, tubes were additionally supplemented with 1 µCi/tube of [methyl-3H]thymidine (Amersham Pharmacia Biotech, Piscataway, NJ). After 24 h of culture, the cells were washed once and resuspended with ice-cold PBS by centrifugation at 2000 x g at 4°C for 30 min. The radioactivity in the washed cell samples was determined after resuspension and scintillation counting in a ß-photomultiplier. The cell numbers were assessed in samples without addition of [3H]thymidine using a hemacytometer (Neubauer; Fisher Scientific, Pittsburgh, PA).
Assessment of Steroid and cAMP Production
Granulosa cells (1 x 105 viable cells/ml) were cultured in 24-well plates (Corning, Corning, NY) in the presence or absence of increasing concentrations of GDF-9 or N-tagged GDF-9 with or without FSH or forskolin. Conditioned medium from nontransfected 293T cells served as negative controls. After 48 h of culture the supernatant was collected and stored at -80°C until measurement of steroid and cAMP content.
Medium progesterone and estrogen content was determined using antisera raised against progesterone-11-hemisuccinate-BSA and estradiol-17ß-O-carboxymethyl-BSA, respectively (generously provided by Bill R. Hopper; Mammoth Lakes, CA). The within-assay coefficient of variation (CVW), between-assay coefficient of variation (CVB), and sensitivity of the progesterone and estrogen assays were less than 2%, 5–7%, and 4–8 pg, respectively. The extracellular content of cAMP in the medium was determined with antibodies against cAMP provided by the National Pituitary and Hormone Program (NHPP, Bethesda, MD). The CVW, CVB, and sensitivity for the cAMP assay were 3.23%, 5.63%, and 0.016 pmol, respectively, after acetylation of samples.
LH/hCG Receptor Measurement
Highly purified hCG (CR129; 14 900 IU/mg) obtained from the NHPP was iodinated using the lactoperoxidase method [29]. The specific activity and maximum binding capacity of the tracer were ~100 000 cpm/ng and 60%, respectively, as determined in a radioligand receptor assay [30]. Granulosa cells were cultured in tubes as described for the thymidine incorporation studies. After 48 h of culture, granulosa cells were centrifuged for 30 min at 4°C. The supernatant was decanted, and culture media were replaced with PBS containing a saturating dose of [125I]iodo-hCG (2 ng/tube) in the absence or presence of excess unlabeled hCG (100 IU hCG/tube). After 18 h incubation at room temperature, ice-cold PBS was added and centrifugation was then performed. The radioactivity of the final pellet was determined using a 
-spectrometer. After correction for the nonspecifically bound radioactivity (in the presence of excess unlabeled hCG), the amount of specifically bound hCG was determined.
Data Analysis
All experimental data are presented as the mean ± SE of duplicate measurements of triplicate cultures. Statistical significance was determined by Students's paired t-test or ANOVA for multiple group comparisons. Significance was accepted at P < 0.05.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
To test the possibility that GDF-9 could regulate granulosa cell proliferation in vitro, granulosa cells from either small antral or preovulatory follicles were cultured for 24 h with labeled thymidine to monitor incorporation into DNA. As shown in Figure 1A, addition of GDF-9 dose-dependently increased the incorporation of thymidine into granulosa cells from small antral follicles, whereas treatment with FSH was ineffective (P > 0.05). N-tagged GDF-9, found to be not bioactive in our earlier studies [22], was also ineffective in stimulating thymidine uptake in granulosa cells. At 10 ng/ml, GDF-9 significantly increased thymidine uptake above the control levels whereas 100 ng/ml GDF-9 induced a maximal 9-fold increase in thymidine incorporation. Likewise, treatment with increasing doses of GDF-9, but not FSH, stimulated thymidine incorporation in granulosa cells from preovulatory follicles (Fig. 1B). At 30 ng/ml, GDF-9 induced a maximal 5-fold increase in thymidine incorporation.
|
To confirm that the observed thymidine incorporation was correlated with cell proliferation, the granulosa cell number was assessed after 24 h of incubation with different doses of GDF-9 (Fig. 1C and D). GDF-9 treatment increased the number of granulosa cells from both types of follicles up to ~2-fold above control levels. This maximum increase in cell number was induced by 150 ng/ml and 30 ng/ml GDF-9 in granulosa from small antral and preovulatory follicles, respectively.
Effect of GDF-9 Treatment on Basal and FSH-stimulated Progesterone and Estrogen Production by Cultured Granulosa Cells
The modulatory effects of GDF-9 on basal and FSH-induced steroidogenesis were assessed in media collected after 48 h of granulosa cell culture. As shown in Table 1, FSH (0.5–50 ng/ml) treatment of granulosa cells from both small antral and preovulatory follicles significantly increased progesterone production. The maximum response was obtained at 5 ng/ml FSH. This dose of FSH was used for subsequent studies on GDF-9 and FSH interactions. Treatment with GDF-9 alone at doses of 100 ng/ml and higher also increased progesterone production in granulosa cells from preovulatory but not small antral follicles, to levels significantly higher than in the controls (Table 1). The elevation of progesterone production induced in granulosa cells from preovulatory follicles by GDF-9 could not be simulated by addition of the same doses of N-tagged GDF-9, thus demonstrating the specific action of GDF-9.
|
Because the granulosa cells from small antral and preovulatory follicles are likely to be under the influence of both FSH and GDF-9, the ability of GDF-9 to modulate FSH action was investigated. As shown in Figure 2A and B, GDF-9 treatment dose-dependently decreased FSH-stimulated progesterone production in granulosa cells from both small antral and preovulatory follicles. In both cell types, a significant decrease was seen at doses higher than 30 ng/ml GDF-9. At 150 ng/ml of GDF-9, FSH-induced progesterone production was suppressed by 56%. The observed suppressive effect of GDF-9 was not due to deleterious effects of the conditioned medium, because the addition of N-tagged GDF-9 at 150 ng/ml or equivalent amounts of conditioned medium from 293T cells did not affect FSH action. GDF-9-induced modulation of basal and FSH-induced estradiol production in cultured granulosa cells was also analyzed. As shown in Table 2, treatment with FSH (5 ng/ml) stimulated estradiol secretion by these cells. Of interest, treatment with increasing doses of GDF-9, but not N-tagged GDF-9, also stimulated estradiol production in granulosa cells from both small antral and preovulatory follicles. At 150 ng/ml GDF-9, a 2- to 4-fold increase in estradiol production was observed. Furthermore, as shown in Figure 3A and B, treatment with GDF-9 significantly reduced FSH-induced estradiol production by granulosa cells from small antral and preovulatory follicles at doses higher than 30 ng/ml GDF-9. At 150 ng/ml, GDF-9 reduced FSH-stimulated estradiol production by 52% and 58% in granulosa cells from small antral and preovulatory follicles, respectively.
|
|
|
GDF-9 Suppression of the Induction of LH Receptor Content by FSH
We further assessed the effect of GDF-9 treatment on the FSH induction of LH receptor content in vitro by a radioligand receptor assay using labeled hCG. After 48 h of culture, treatment with FSH (5 ng/ml), but not GDF-9, increased the amount of 125I-hCG binding by 6-fold in granulosa cells from small antral follicles as compared with controls. This binding was dose-dependently reduced by cotreatment with GDF-9 (Fig. 4A), with a significant decrease observed at 10 ng/ml of GDF-9. Although granulosa cells from preovulatory follicles had higher basal levels of LH receptor (Fig. 4B), treatment with FSH further increased 125I-hCG binding by 4-fold. Similar to findings for granulosa cells from less mature follicles, treatment with GDF-9 at 30 ng/ml and higher also significantly decreased FSH-induced 125I-hCG binding. At 150 ng/ml, GDF-9 completely reduced FSH-induced 125I-hCG binding to levels similar to those for controls in both types of granulosa cells. In contrast, treatment with N-tagged GDF-9 (150 ng/ml) or equivalent amounts of conditioned medium from nontransfected 293T cells did not significantly affect FSH-induced 125I-hCG binding.
|
GDF-9 Modulation of FSH-stimulated cAMP Production by Cultured Granulosa Cells
Because FSH stimulation of both steroidogenesis and LH receptor content in granulosa cells is mediated by an increase in cAMP levels [8], we further tested the effect of GDF-9 treatment on cAMP production by cultured granulosa cells (Fig. 5). The extracellular cAMP levels were significantly increased after treatment with FSH (5 ng/ml) in granulosa cells from both small antral and preovulatory follicles, whereas treatment with GDF-9 (150 ng/ml) alone was ineffective. As shown in Figure 5A, treatment with 30 ng/ml GDF-9 significantly reduced FSH-stimulated cAMP production in granulosa cells from small antral follicles. At 150 ng/ml, GDF-9 reduced FSH-induced cAMP production by 58%. In contrast, in granulosa cells from preovulatory follicles, 150 ng/ml of GDF-9 was required to decrease FSH-induced cAMP production. This dose of GDF-9 suppressed FSH action only by 23% (Fig. 5B). In granulosa cells from both types of follicles, treatment with N-tagged GDF-9 (150 ng/ml) or equivalent amounts of conditioned medium from nontransfected 293T cells did not significantly affect FSH-induced cAMP production.
|
GDF-9 Modulation of Granulosa Cell Differentiation Induced by Forskolin
To assess whether GDF-9 influences FSH-mediated granulosa cell differentiation by affecting cAMP production or post-cAMP steps, we tested the GDF-9 modulation of steroidogenesis and cAMP production induced by forskolin, a diterpene activator of adenyl cyclase. As shown in Figure 6A and B, GDF-9 did not significantly reduce progesterone and estradiol biosynthesis induced by forskolin in granulosa cells from both early antral and preovulatory follicles (P > 0.05). Similarly, the levels of cAMP stimulated by forskolin in both types of granulosa cells were also not significantly reduced by GDF-9 (Fig. 6C; P > 0.05).
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
In our earlier study [22] we found that GDF-9 treatment induces the growth of preantral follicles in culture, likely as the result of stimulating granulosa cell proliferation in these immature follicles. The current study further showed that the mitotic effect of GDF-9 is also present in granulosa cells from small antral and preovulatory follicles as reflected by increases in both thymidine incorporation and granulosa cell number. The increase in cell number in the present culture system is consistent with reports showing a doubling time of 24 h for granulosa cells during the late stages of follicular growth in vivo [1]. Of interest, the effect of GDF-9 on cell proliferation is more pronounced in granulosa cells from small antral follicles than from preovulatory follicles, consistent with the existence of more terminally differentiated cells in the latter group. As GDF-9 protein is found in oocytes from primary to preovulatory follicles in rodents [22,27], this oocyte factor could be important in the promotion of follicle growth during most of the follicle life. Therefore, GDF-9 not only is necessary for the initiation of early follicle growth as manifested in the phenotypes of GDF-9-deficient mice [23] but also contributes to follicular growth at later stages of follicle development. The observed promotion of granulosa cell proliferation by GDF-9 is consistent with the hypothesis that oocyte factors enhance granulosa cell division [16]. Because the present in vitro culture represents a mixed population of granulosa cells that could possess differing GDF-9 responsiveness, future studies on subpopulations of these cells would be of interest.
In contrast to the profound proliferating action of GDF-9 on cultured granulosa cells, FSH treatment is ineffective in vitro as shown in this and earlier studies [31]. However, FSH was shown to induce rat follicular growth in vitro and thymidine incorporation in vivo [26,32]. Therefore, the action of FSH on follicular growth might involve different paracrine factors secreted by the neighboring theca cells or by the oocyte. Factors that have been suggested to be responsible for FSH-induced follicular growth include epidermal growth factor [33] and several members of the TGF-ß superfamily. Treatment of granulosa cells with either activin or TGF-ß has been shown to stimulate thymidine uptake in vitro; the latter was also shown to increase granulosa cell number [31,34–35].
In antral follicles, the granulosa cells closest to the basal lamina are highly differentiated as reflected by their high steroidogenic potential and LH receptor content [12–15]. In contrast, the cumulus cells surrounding the oocyte are less differentiated, showing lower steroid production and LH receptor levels. The undifferentiated status of the cumulus cells is necessary for optimal oocyte development [36], whereas the highly differentiated mural granulosa cells are essential for steroidogenesis as well as follicle rupture induced by the preovulatory LH surge [37]. Although the present in vitro studies suggest that the oocyte, via the secretion of GDF-9, could prevent the FSH promotion of steroidogenesis and LH receptors in its surrounding cumulus cells, future in vivo experiments are needed to substantiate this concept. A concentration gradient of the paracrine factor GDF-9 established by the oocyte could provide the basis to explain the stratification of granulosa cells in antral and preovulatory follicles, and the oocyte itself could be largely responsible for the development of two distinct subpopulations of granulosa cells.
The putative receptors mediating GDF-9 action have not been described. Members of the TGF-ß superfamily are known to serve as specific ligands for type II receptors that interact with the type I receptors following ligand binding and receptor phosphorylation, thus leading to signal transduction [38,39]. It is likely that GDF-9 could also interact with its own specific serine kinase receptors in the granulosa cells or even with receptors known to bind other family members.
To date the ability of GDF-9 to regulate different cellular pathways is not known, and the present findings suggest that GDF-9 treatment does not stimulate cAMP production by granulosa cells. In contrast, cotreatment with GDF-9 decreased FSH-induced cAMP production, which could be partially responsible for the GDF-9 suppression of FSH-induced steroidogenesis and LH receptor formation in cultured granulosa cells. However, treatment with GDF-9 did not affect forskolin-induced cAMP production or steroidogenesis. It remains to be elucidated whether the GDF-9 suppression of FSH action is due to the modulation of FSH receptor content or FSH receptor coupling to the Gs protein. However, the GDF-9 suppression of FSH-stimulated cAMP production, unlike its inhibition of FSH-stimulated steroidogenesis and LH receptor formation, is incomplete and occurs only at high concentrations. The observed discrepancies could be the results of intracellular compartmentalization of cAMP [40]. Even without increasing basal cAMP production, treatment with GDF-9 itself is capable of increasing basal progesterone production—consistent with an earlier study showing increases in StAR mRNA induced by GDF-9 [26]. In addition, we show that GDF-9 increases basal estradiol levels by granulosa cells from both small antral and preovulatory follicles. It is interesting to note that the stimulatory effects of GDF-9 required higher concentrations of the hormone than did its inhibitory effects on FSH action, raising the possibility that the former effects are pharmacological in nature. The observed GDF-9 stimulation of both progesterone and estradiol in the absence of changes in basal cAMP levels suggests that this GDF-9 action on basal steroidogenesis is mediated by a pathway independent of cAMP stimulation. The observation that treatment with GDF-9—but not the cAMP-inducing FSH—stimulates granulosa cell proliferation further underscores the cAMP-independent nature of GDF-9 action. Future measurement of protein kinase A activity, and elucidation of the intracellular pathways by which GDF-9 enhances granulosa cell proliferation and basal steroidogenesis, are of interest.
The diverse effects of GDF-9 on granulosa cell function shown in this study are likely related to the different regulatory effects of oocyte-conditioned medium on cumulus/granulosa cells reported in earlier studies [16–19]. These earlier studies showed that one or more oocyte-secreted factors inhibit FSH stimulation of steroidogenesis and LH receptor expression [17,18]. Furthermore, oocyte factors induce granulosa cell proliferation and enable FSH-induced cumulus expansion [16,19]. GDF-9 induces proliferation of granulosa cells from different follicular stages and might well be responsible for follicular growth induced by the oocyte. Furthermore, the observed GDF-9 inhibition of FSH-induced differentiation of granulosa cells could explain the distinct differences between undifferentiated cumulus cells surrounding the oocyte and more differentiated mural granulosa cells. Therefore, the paracrine factor GDF-9 is likely the main hormone involved in the oocyte control of folliculogenesis. Because immunostaining analysis suggested that individual oocytes in different antral follicles display varying levels of GDF-9 expression [22,27], differences in GDF-9 production by the oocyte in a given follicle could also be responsible for variations in individual follicle development. GDF-9 is not the only hormone expressed by oocytes in follicles of different follicular stages. It was recently indicated that GDF-9B (BMP-15) is coexpressed with GDF-9 throughout different stages of folliculogenesis [41,42]. Similar to GDF-9, this factor is expressed by the oocyte beginning at the one-layer primary follicle stage and continuing through ovulation. In the human ovary, GDF-9 was found to be expressed in early primary follicles, whereas GDF-9B is not expressed until the later primary follicle stages [25]. It remains to be elucidated whether GDF-9 interacts with GDF-9B to modulate follicle development. Further studies of various oocyte-secreted factors and their effects, alone or in combination, on folliculogenesis in vitro and in vivo are necessary for understanding of the role of the oocyte in the control of follicle development. These studies could eventually lead to a refinement of in vitro reproductive techniques.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
1 This study was supported by NIH Grant HD31398 and the Specialized Cooperative Centers Program in Reproduction Research. 
2 Correspondence: Aaron J.W. Hsueh, Division of Reproductive Biology, Department of Gynecology and Obstetrics, Stanford University School of Medicine, Room A344, Stanford, CA 94305-5317. FAX: 650 725 7102; aaron.hsueh{at}stanford.edu
Accepted: September 24, 1999.
Received: July 8, 1999.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
. Biol Reprod 1994; 50:940–948.[Abstract]This article has been cited by other articles:
|
|
 |
|
  T. da Silva Faria, F. de Bittencourt Brasil, F. J B Sampaio, and C. da Fonte Ramos Maternal malnutrition during lactation alters the folliculogenesis and gonadotropins and estrogen isoforms ovarian receptors in the offspring at puberty J. Endocrinol., September 1, 2008; 198(3): 625 - 634. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. B. Gilchrist, M. Lane, and J. G. Thompson Oocyte-secreted factors: regulators of cumulus cell function and oocyte quality Hum. Reprod. Update, March 1, 2008; 14(2): 159 - 177. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. J Spicer, P. Y Aad, D. T Allen, S. Mazerbourg, A. H Payne, and A. J Hsueh Growth Differentiation Factor 9 (GDF9) Stimulates Proliferation and Inhibits Steroidogenesis by Bovine Theca Cells: Influence of Follicle Size on Responses to GDF9 Biol Reprod, February 1, 2008; 78(2): 243 - 253. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-Q. Su, K. Sugiura, K. Wigglesworth, M. J. O'Brien, J. P. Affourtit, S. A. Pangas, M. M. Matzuk, and J. J. Eppig Oocyte regulation of metabolic cooperativity between mouse cumulus cells and oocytes: BMP15 and GDF9 control cholesterol biosynthesis in cumulus cells Development, January 1, 2008; 135(1): 111 - 121. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Zachow and M. Uzumcu The hepatocyte growth factor system as a regulator of female and male gonadal function J. Endocrinol., December 1, 2007; 195(3): 359 - 371. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. Pangas, C. J. Jorgez, M. Tran, J. Agno, X. Li, C. W. Brown, T. R. Kumar, and M. M. Matzuk Intraovarian Activins Are Required for Female Fertility Mol. Endocrinol., October 1, 2007; 21(10): 2458 - 2471. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S Elis, J Dupont, I Couty, L Persani, M Govoroun, E Blesbois, F Batellier, and P Monget Expression and biological effects of bone morphogenetic protein-15 in the hen ovary J. Endocrinol., September 1, 2007; 194(3): 485 - 497. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Gazdag, A. Rajkovic, M. E. Torres-Padilla, and L. Tora Analysis of TATA-binding protein 2 (TBP2) and TBP expression suggests different roles for the two proteins in regulation of gene expression during oogenesis and early mouse development Reproduction, July 1, 2007; 134(1): 51 - 62. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Stocco, C. Telleria, and G. Gibori The Molecular Control of Corpus Luteum Formation, Function, and Regression Endocr. Rev., February 1, 2007; 28(1): 117 - 149. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Liu and W. Ge Growth Differentiation Factor 9 and Its Spatiotemporal Expression and Regulation in the Zebrafish Ovary Biol Reprod, February 1, 2007; 76(2): 294 - 302. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Liu, S. Rajareddy, P. Reddy, C. Du, K. Jagarlamudi, Y. Shen, D. Gunnarsson, G. Selstam, K. Boman, and K. Liu Infertility caused by retardation of follicular development in mice with oocyte-specific expression of Foxo3a Development, January 1, 2007; 134(1): 199 - 209. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Miyoshi, F. Otsuka, K. Inagaki, H. Otani, M. Takeda, J. Suzuki, J. Goto, T. Ogura, and H. Makino Differential Regulation of Steroidogenesis by Bone Morphogenetic Proteins in Granulosa Cells: Involvement of Extracellularly Regulated Kinase Signaling and Oocyte Actions in Follicle-Stimulating Hormone-Induced Estrogen Production Endocrinology, January 1, 2007; 148(1): 337 - 345. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Choi and A. Rajkovic Characterization of NOBOX DNA Binding Specificity and Its Regulation of Gdf9 and Pou5f1 Promoters J. Biol. Chem., November 24, 2006; 281(47): 35747 - 35756. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Orisaka, S. Orisaka, J.-Y. Jiang, J. Craig, Y. Wang, F. Kotsuji, and B. K. Tsang Growth Differentiation Factor 9 Is Antiapoptotic during Follicular Development from Preantral to Early Antral Stage Mol. Endocrinol., October 1, 2006; 20(10): 2456 - 2468. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. De, J.-I. Park, K. Kawamura, R. Chen, C. Klein, R. Rauch, S. M. Mulders, M. D. Sollewijn Gelpke, and A. J. W. Hsueh Intraovarian Tumor Necrosis Factor-Related Weak Inducer of Apoptosis/Fibroblast Growth Factor-Inducible-14 Ligand-Receptor System Limits Ovarian Preovulatory Follicles from Excessive Luteinization Mol. Endocrinol., October 1, 2006; 20(10): 2528 - 2538. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. B. Gilchrist, L. J. Ritter, S. Myllymaa, N. Kaivo-Oja, R. A. Dragovic, T. E. Hickey, O. Ritvos, and D. G. Mottershead Molecular basis of oocyte-paracrine signalling that promotes granulosa cell proliferation J. Cell Sci., September 15, 2006; 119(18): 3811 - 3821. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. G Knight and C. Glister TGF-{beta} superfamily members and ovarian follicle development. Reproduction, August 1, 2006; 132(2): 191 - 206. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Mazerbourg and A. J.W. Hsueh Genomic analyses facilitate identification of receptors and signalling pathways for growth differentiation factor 9 and related orphan bone morphogenetic protein/growth differentiation factor ligands Hum. Reprod. Update, July 1, 2006; 12(4): 373 - 383. [Abstract] [Full Text] [PDF]
|
|
