Growth Factors in Human Ovarian Follicle Fluid and Growth Factor Receptors in Granulosa-Luteal Cells

Cell-Type Localization of Platelet-Derived Growth Factors and Receptors in the Postnatal Rat Ovary and Follicle1

Intraovarian growth factors play a significant role in the regulation of follicular selection and growth. In this study, the presence and localization of all members of the family of platelet-derived growth factors (PDGF) and receptors (PDGFR) were identified and characterized in the rat ovary. In addition, a role was identified for members of this family in contributing towards growth of preantral follicles. Real-time PCR revealed the presence of mRNA for all platelet-derived growth factors (Pdgfa, Pdgfb, Pdgfc and Pdgfd) and receptors (Pdgfra and Pdgfrb) in the rat ovary from birth until 4 wk. In situ hybridization and immunohistochemistry were utilized to identify cell-type expression of PDGFs and PDGFRs in rat ovaries from birth until 4 wk. Shortly after birth, expression of PDGFRA and PDGFC was observed in and around oocyte clusters, and PDGFRB in stromal cells surrounding oocyte clusters. All members were identified in oocytes of primordial and primary follicles, and in cells of the theca layer of primordial to antral follicles. PDGFRA and PDGFA were also localized to some granulosa cells of secondary and antral follicles in ovaries from rats at Days 20 and 24. Thus, localization data suggest both theca-theca and theca-granulosa cell interactions of PDGFs and receptors. Preantral follicles cultured in vitro over 5 days in serum-free medium plus recombinant PDGFAA, PDGFAB, or PDGFBB increased in follicle diameter by 18.32%+/-2.18%, 17.72%+/-2.3%, and 17.6%+/-1.81%, respectively, representing significantly greater increases than for follicles incubated in serum-free medium alone (11%+/-1.57%), and suggesting a role for these growth factors in positively influencing early follicle growth.

Platelet-Derived Growth Factors and Receptors in the Rat Corpus Luteum: Localization and Identification of an Effect on Luteogenesis1

Platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) play a vital role in regulating cell growth and angiogenesis. In this study, the expression of the family of PDGFs and PDGFRs in the ovarian corpus luteum were identified and characterized, and an effect of their activity on development of the corpus luteum revealed. Gonadotropin-stimulated immature rats were utilized as a model of induced ovulation, luteogenesis, and pseudopregnancy. Levels of ovarian mRNA for Pdgfb and Pdgfd, and their receptor, Pdgfrb, increased significantly as early as 4 h after human chorionic gonadotropin (hCG) injection in immature rats primed with equine chorionic gonadotropin (eCG). Gonadotropin regulation of Pdgfb expression was confirmed by in vitro promoter-reporter assays, which showed a 2- to 3-fold increase in Pdgfb promoter activity in response to luteinizing hormone (LH). Inhibition studies implicated protein kinase A, phosphatidylinositol 3-kinase and mitogen activated protein kinase signaling pathways in the LH-induced upregulation. In the corpus luteum, PDGFA, PDGFB, PDGFC, and PDGFRA were localized to a population of luteal parenchymal/steroidogenic cells. PDGFRB was expressed primarily in what appeared to be cells of the luteal microvasculature. Intraovarian injection of an inhibitor of PDGF receptor activity, the tyrphostin AG1295, prior to injection of hCG in eCG-primed immature rats resulted in a significant 21.86%+/-11.15% decrease in corpora lutea per treated ovary in comparison to the contralateral vehicle-injected control ovary. In addition, the treated ovary of 3 of 16 rats showed widespread hemorrhage throughout the entire ovary, indicating a possible role for PDGF receptor activity in maintenance of the ovarian vasculature.

Aberrant expression of PDGF ligands and receptors in the tumor prone ovary of follitropin receptor knockout (FORKO) mouse

Although PDGF family members play a vital role in cell proliferation, motility and chemotaxis via activation of structurally similar alpha- and beta-receptors, little is known of their function in ovarian regulation and induction of tumorigenesis. Microarray analyses of ovaries from young follitropin receptor knockout (FORKO) mice that are prone to late ovarian tumors upon aging have revealed significant imbalances in PDGF ligands and receptors. We hypothesized that FSH/FSH-R signaling may exert effects partly by regulation of PDGF the family. To further understand their implications for ovarian tumorigenesis, we studied FORKO ovaries and hormonal regulation of the PDGF family members in normal mice, by using RT-PCR, Q-PCR, immunohistochemistry and western blotting. While PDGF-C and PDGFR-alpha increased, PDGFR-beta mRNA and protein decreased significantly in absence of FSH-R signaling. In the normal ovary, PDGFR-alpha was not affected by gonadotropin (eCG) stimulation but PDGF-C and PDGFR-beta decreased. Administration of estradiol decreased PDGF and their receptors. To further probe the differential regulation of PDGF family members by eCG and estradiol, we co-administered eCG with estrogen antagonist, ICI 182780. Increase in PDGFR-alpha in the absence of estradiol suggests direct effects of FSH signaling. During the estrous cycle in mice PDGF-C, PDGF-D and PDGFR-alpha mRNA levels were higher at the proestrous. By IHC, we report for the first time the localization of PDGF-C, PDGFR-alpha and PDGFR-beta protein in mouse ovarian compartments including the surface epithelium that is also altered in mutants. Immunostaining of PDGFRs increased as the follicle developed to preantral stage and declined thereafter. Thus, FSH modulates PDGF family members, partly via E2, suggesting that loss of FSH-R signaling causes an imbalance of PDGF family members predisposing the abnormal ovarian follicular environment for inducing tumorigenesis in aging FORKO mice.

Immunohistochemical detection of transforming growth factor-α, epidermal growth factor, and vascular endothelial growth factor expression in hyperstimulated rat ovary

OBJECTIVE

The aim of the present study is to figure out the immunohistochemical expression of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) in hyperstimulated rat ovaries.

METHODS

Twenty Wistar-Albino adult female rats (250-300 g) were taken into the study. The animals were randomly divided into two groups, each containing 10 rats: (i) stimulation group and (ii) control group. In the stimulation group, a stimulation regimen was administered to induce follicular maturity and ovarian hyperstimulation syndrome (OHSS) at the end using a 30-IU follicle-stimulating hormone that was administered subcutaneously for 4 consecutive days, followed by a 30-IU human chorionic gonadotropin on day 5 to induce ovulation. The rats, in the control group, received 0.2 ml of 0.9% NaCl for 5 consecutive days to mimic the conditions of the study animals. At the end of the treatment period, all rats underwent ovariectomy and the sections of ovaries were stained for the TGF-alpha, EGF, and VEGF.

RESULTS

The expression of TGF-alpha, EGF, and VEGF in the endothelium, the stroma, the granulosa cells, and the corpus luteum was found to be significantly higher in the stimulated group, compared to that in the control group ( p < 0.05).

CONCLUSION

TGF-alpha, EGF, and VEGF are found to have increased in the hyperstimulated ovaries and this finding seems to be involved in the OHSS pathogenesis.

The TGF-beta superfamily and its roles in the human ovary and placenta

The transforming growth factor-beta (TGF-beta) superfamily consists of a large group of growth and differentiation factors, such as TGF-betas, activins, inhibins, growth and differentiation factors (GDFs), and bone morphogenetic proteins (BMPs). These molecules act through specific receptor complexes that are composed of type I and type II serine/threonine receptor kinases. The receptor kinases subsequently activate Smad proteins, which then propagate the signals into the nucleus to regulate target gene expression. Several ligands in this family, such as TGF-betas, activins, inhibins, BMP-15, and GDF-9, play important roles in regulating human ovarian functions, including follicle development and maturation. Activin and TGF-beta are also involved in regulating placental development and functions. Abnormal expression or function of these ligands has been found in several pathological conditions. This review summarizes the role of the TGF-beta superfamily in human ovarian and placental regulation and function, and the potential clinical implications.

Differentiation-dependent expression of connective tissue growth factor and lysyl oxidase messenger ribonucleic acids in rat granulosa cells

Searching for novel genes involved in tissue remodeling during ovarian folliculogenesis, we carried out differential display RT-PCR (DDRT-PCR) on RNA from gonadotropin-stimulated rat granulosa cells (GC). GC from preantral and early antral follicles in immature rat ovaries were cultured in serum-free medium containing no hormone (control), recombinant human FSH (10 ng/ml), 5alpha-dihydrotestosterone (DHT; 10(-6) M), or FSH plus DHT. Total cellular RNA was extracted from cells at 6, 12, 24, and 48 h of treatment for DDRT-PCR analysis, corresponding to an estimated 60% saturation of the messenger RNA (mRNA) population. Six distinct complementary DNA clones were obtained that reproduced the DDRT-PCR profile on a Northern blot of the corresponding RNA samples. Two of these clones detected transcripts that were strongly down-regulated by FSH. One corresponded to connective tissue growth factor (CTGF), a cysteine-rich secreted protein related to platelet-derived growth factor that is implicated in mitogenesis and angiogenesis, and a second was identical to lysyl oxidase (LO), a key participant in extracellular matrix deposition. In detailed expression studies, Northern analysis revealed a single, approximately 2.5-kb CTGF transcript maximally suppressed within 3 h of exposure to FSH with or without DHT and two LO transcripts ( approximately 3.8 and approximately 5.2 kb) maximally suppressed at 6 h. DHT alone did not affect CTGF mRNA, but strongly enhanced LO mRNA relative to the control value. In vivo, CTGF and LO transcripts were significantly suppressed in GC 48 h after equine CG injection (10 IU, ip) compared with untreated controls and were further reduced 12 h after administration of additional 10 IU hCG to induce luteinization. In situ hybridization confirmed GC in preantral/early antral follicles as principal sites of CTGF and LO mRNA expression. We conclude that expression of CTGF and LO mRNAs is inversely related to GC differentiation. The encoded proteins probably have roles in the regulation of tissue remodeling and extracellular matrix formation during early follicular development.

The influence of blood cells and PDGF on porcine theca cell function in vitro

The role of red and white blood cells in the regulation of porcine theca cell function is poorly understood. Interactions between these cell types and a potential mediator of any interaction, PDGF, were investigated using a serum-free culture system. Theca cells were collected from 6-9mm antral follicles and plated at 50x10(3) viable cells/well. In the first experiment, macrophages were removed and theca cells+/-macrophages were cultured with a range of PDGF doses (0.1, 1, and 10ng/ml)+/-IGF-1. In the second experiment, red blood cells were removed with lysing buffer. In both experiments the effect of treatment on steroidogenesis and viable cell number was examined. Macrophage removal decreased oestradiol production but increased androstenedione output irrespective of the presence of IGF-1 (oestradiol+/-IGF-1, P<0.001; androstenedione P=0.02 without IGF-1, P<0.001 with IGF-1). PDGF increased oestradiol synthesis by whole and macrophage-free theca cell preparations but only in the presence of IGF-1 (P<0.001). In contrast, androstenedione production was unaffected by PDGF dose in the presence of IGF-1 (P=0.67). Without IGF-1, 10ng/ml PDGF tended to decrease androstenedione levels (P=0.06). Macrophage removal increased viable cell number at 144h (P<0.001+/-IGF-1) as did PDGF (P<0.001+/-IGF-1). In the absence of IGF-1, there was a PDGF x cell type interaction (P=0.02). Macrophage-free cultures with 10ng/ml PDGF had twice as many viable cells as whole preparations with no PDGF. In the second experiment, red blood cell removal did not affect steroidogenesis or the number of viable cells present at 144h when cells were cultured with IGF-1. The data show that theca cell/macrophages interactions do occur, and influence both steroidogenesis and viable cell number during culture. The macrophage product(s) enhanced oestradiol synthesis but reduced androstenedione production and the number of viable cells. As all these interactions were not mimicked by PDGF, PDGF cannot be the only factor mediating the theca/macrophage interaction. When cultured under optimised conditions the presence of red blood cells was not detrimental to theca cell steroidogenesis or the number of viable cells.

Effects of chocolate cyst fluid on endometrioma cell growth in culture

OBJECTIVE

To evaluate the effect of chocolate cyst fluid on the proliferation of cultured human endometrioma cells and to assay the concentration of transforming growth factor-B1 in this fluid.

DESIGN

Controlled in vitro study.

SETTING

Department of Obstetrics and Gynecology, State University of New York Health Science Center.

PATIENT(S)

Five women with ovarian endometriomas.

INTERVENTION(S)

Endometrioma tissue and chocolate fluid from five different patients were entered in this study.

MAIN OUTCOME MEASURE(S)

Endometrioma cell proliferation in culture with and without chocolate cyst fluid.

RESULT(S)

Chocolate cyst fluid increased the proliferation of endometrioma cells compared with controls. Also, high concentrations of transforming growth factor-B1 were found in cysts' fluid.

CONCLUSIONS

Chocolate cyst fluid has a growth-enhancing effect on endometrioma cells. One promoting growth factor is transforming growth factor-B1.