PKA and AMPK Signaling Pathways Differentially Regulate Luteal Steroidogenesis.

Luteinizing hormone (LH) via protein kinase A (PKA) triggers ovulation and formation of the corpus luteum, which arises from the differentiation of follicular granulosa and theca cells into large and small luteal cells, respectively. The small and large luteal cells produce progesterone, a steroid hormone required for establishment and maintenance of pregnancy. We recently reported on the importance of hormone-sensitive lipase (HSL, also known as LIPE) and lipid droplets for appropriate secretory function of the corpus luteum. These lipid-rich intracellular organelles store cholesteryl esters, which can be hydrolyzed by HSL to provide cholesterol, the main substrate necessary for progesterone synthesis. In the present study, we analyzed dynamic posttranslational modifications of HSL mediated by PKA and AMP-activated protein kinase (AMPK) as well as their effects on steroidogenesis in luteal cells. Our results revealed that AMPK acutely inhibits the stimulatory effects of LH/PKA on progesterone production without reducing levels of STAR, CYP11A1, and HSD3B proteins. Exogenous cholesterol reversed the negative effects of AMPK on LH-stimulated steroidogenesis, suggesting that AMPK regulates cholesterol availability in luteal cells. AMPK evoked inhibitory phosphorylation of HSL (Ser565). In contrast, LH/PKA decreased phosphorylation of AMPK at Thr172, a residue required for its activation. Additionally, LH/PKA increased phosphorylation of HSL at Ser563, which is crucial for enzyme activation, and decreased inhibitory phosphorylation of HSL at Ser565. The findings indicate that LH and AMPK exert opposite posttranslational modifications of HSL, presumptively regulating cholesterol availability for steroidogenesis.

Prolyl oligopeptidase regulates progesterone secretion via the ERK signaling pathway in murine luteal cells.

Prolyl oligopeptidase (POP), one of the most widely distributed serine endopeptidases, is highly expressed in the ovaries. However, the physiological role of POP in the ovaries is not clear. In this study, we investigated the significance of POP in the corpus luteum. Murine luteal cells were cultured in vitro and treated with a POP selective inhibitor, (2S)-1[[(2 S)-1-(1-oxo-4-phenylbutyl)-2-pyrrolidinyl carbonyl]-2-pyrrolidinecarbonitrile (KYP-2047). We found that KYP-2047 treatment decreased progesterone secretion. In contrast, POP overexpression increased progesterone secretion. Three essential steroidogenic enzymes, including p450 cholesterol side-chain cleavage enzyme (CYP11A), 3ß-hydroxysteroid dehydrogenase (3ß-HSD), and the steroidogenic acute regulatory protein (StAR), were regulated by POP. Further studies showed that POP overexpression increased ERK1/2 phosphorylation and increased the expression of steroidogenic factor 1 (SF1), while KYP-2047 treatment decreased ERK1/2 phosphorylation and SF1 expression. To clarify the role of ERK1/2 signaling in POP-regulated progesterone synthesis, U0126-EtOH, an inhibitor of the ERK signaling pathway, was used to treat luteal cells. We found that U0126-EtOH decreased progesterone production and the expression of steroidogenic enzymes and SF1. POP overexpression did not reverse the effects of U0126-EtOH. Overall, POP regulates progesterone secretion by stimulating the expression of CYP11A, 3ß-HSD, and StAR in luteal cells. ERK signaling and downstream SF1 expression contribute to this process.

Granulosa-Lutein Cell Sirtuin Gene Expression Profiles Differ between Normal Donors and Infertile Women.

Sirtuins are a family of deacetylases that modify structural proteins, metabolic enzymes, and histones to change cellular protein localization and function. In mammals, there are seven sirtuins involved in processes like oxidative stress or metabolic homeostasis associated with aging, degeneration or cancer. We studied gene expression of sirtuins by qRT-PCR in human mural granulosa-lutein cells (hGL) from IVF patients in different infertility diagnostic groups and in oocyte donors (OD; control group). Study 1: sirtuins genes' expression levels and correlations with age and IVF parameters in women with no ovarian factor. We found significantly higher expression levels of SIRT1, SIRT2 and SIRT5 in patients ≥40 years old than in OD and in women between 27 and 39 years old with tubal or male factor, and no ovarian factor (NOF). Only SIRT2, SIRT5 and SIRT7 expression correlated with age. Study 2: sirtuin genes' expression in women poor responders (PR), endometriosis (EM) and polycystic ovarian syndrome. Compared to NOF controls, we found higher SIRT2 gene expression in all diagnostic groups while SIRT3, SIRT5, SIRT6 and SIRT7 expression were higher only in PR. Related to clinical parameters SIRT1, SIRT6 and SIRT7 correlate positively with FSH and LH doses administered in EM patients. The number of mature oocytes retrieved in PR is positively correlated with the expression levels of SIRT3, SIRT4 and SIRT5. These data suggest that cellular physiopathology in PR's follicle may be associated with cumulative DNA damage, indicating that further studies are necessary.

Inductions of granulosa cell luteinization and cumulus expansion are dependent on the fibronectin-integrin pathway during ovulation process in mice.

It has been known that EGF-like factor secreted from LH-stimulated granuloma cells acts on granulosa cells and cumulus cells to induce ovulation process. Granulosa cells are changed the morphology with differentiating cell functions to produce progesterone. Cumulus cells are detached to make a space between the cells to accumulate hyaluronan rich matrix. LH also changes extracellular matrix (ECM) components including fibronectin in the follicular walls and granulosa cell layers. EGF like factor and fibronectin synergistically play important roles in numerous cell functions, especially cancer cell migration, estimating that fibronectin would impact on granulosa cells and cumulus cells. To clear this hypothesis, the localizations of fibronectin and its receptor integrin were observed by immunofluorescence technique. The functions were monitored by the detection of downstream signaling pathway, focal adhesion kinase (FAK). The pharmacological approach in both in vivo and in vitro were used for analyzing the physiological roles of FAK during ovulation process. The immunofluorescence staining revealed that fibronectin and integrin were observed in granulosa cells, cumulus cells and the space between cumulus cells and oocyte at 4 and 8 h after hCG injection. Concomitantly with the changes of fibronectin-integrin localization, FAK was phosphorylated in periovulatory follicles. The injection of FAK inhibitor suppressed not only ovulation but also luteinization of granulosa cells and cumulus expansion. In cultured-granulosa cells, fibronectin-integrin synergistically activated FAK with amphiregulin (AREG). Such cooperative stimulations induced a morphological change in granulosa cells, which resulted in the maximum level of progesterone production via the induction of Hsd3b. When cumulus-oocyte complexes (COCs) were cultured with AREG in the presence of serum, the maximum level of cumulus expansion was observed. The AREG-induced cumulus expansion was also suppressed by FAK inhibitor. Thus, it is concluded that fibronectin and AREG synergistically activate FAK not only in granulosa cells and cumulus cells to induce successful ovulation process.

Activin A-induced increase in LOX activity in human granulosa-lutein cells is mediated by CTGF.

Lysyl oxidase (LOX) is the key enzyme involved in the crosslinking of collagen and elastin that is essential for the formation of extracellular matrix (ECM). LOX-mediated ECM remodeling plays a critical role in follicle development, oocyte maturation and corpus luteum formation. To date, the regulation of LOX in human ovary has never been elucidated. Activin A and its functional receptors are highly expressed in ovarian follicles from an early developmental stage. They locally regulate follicle progression. The aim of this study was to investigate the effects of activin A on the expression of LOX and its extracellular enzyme activity in primary and immortalized human granulosa-lutein cells obtained from patients undergoing an in vitro fertilization procedure. We demonstrated that activin A significantly upregulated the expression of connective tissue growth factor (CTGF) and LOX via an activin/TGF-ß type I receptor mediated-signaling pathway. Using a target depletion small interfering RNA knockdown approach, we further confirmed that the upregulation of CTGF expression resulted in an activin-A-induced increases in LOX expression and activity. These findings may provide insight into the mechanisms by which intrafollicular growth factors regulate the expression of LOX for ECM formation and tissue remodeling in the human ovary.

Lysophosphatidic acid modulates prostaglandin signalling in bovine steroidogenic luteal cells.

We examined whether lysophosphatidic acid affects prostaglandin biosynthesis, transport, and signalling in bovine steroidogenic luteal cells. The aim of the present study was to determine the influence of LPA on PGE2 and PGF2α synthesis and on the expression of enzymes involved in PG biosynthesis (PTGS2, mPGES-1, cPGES, mPGES-2, PGFS and 9-KPR), prostaglandin transporter (PGT), and prostaglandin receptors (EP1, EP2, EP3, EP4 and FP) in bovine steroidogenic luteal cells. We found that LPA inhibited PGF2α synthesis in steroidogenic luteal cells. Moreover, LPA increased mPGES1 and cPGES and decreased PGFS expression in cultured bovine steroidogenic luteal cells. Additionally, LPA stimulated EP2 and EP4 receptor and PGT expression. This study suggests that LPA activity in the bovine CL directs the physiological intraluteal balance between the two main prostanoids towards luteotropic PGE2.

Expression of matrix metalloproteinases in bovine luteal cells induced by prostaglandin F2α, interferon γ and tumor necrosis factor α.

We recently demonstrated that luteal cells flow out from the ovary via lymphatic vessels during luteolysis. However, the regulatory mechanisms of the outflow of luteal cells are not known. Matrix metalloproteinases (MMPs) can degrade the extracellular matrix and basal membrane, and tissue inhibitors of matrix metalloproteinases (TIMPs) inhibit the activity of MMPs. To test the hypothesis that MMP expression in luteal cells is regulated by luteolytic factors, we investigated the effects of prostaglandin F2α (PGF), interferon γ (IFNG) and tumor necrosis factor α (TNF) on the mRNA expression of MMPs and TIMPs in cultured luteal cells. Luteal cells obtained from the CL at the mid-luteal stage (days 8-12 after ovulation) were cultured with PGF (0.01, 0.1, 1 µM), IFNG (0.05, 0.5, 5 nM) and TNF (0.05, 0.5, 0.5 nM) alone or in combination for 24 h. PGF and IFNG significantly increased the expression of MMP-1 mRNA. In addition, 1 µM PGF in combination with 5 nM IFNG stimulated MMP-1 and MMP-9 mRNA expression significantly more than either treatment alone. In contrast, IFNG significantly decreased the level of MMP-14 mRNA. The mRNA expression of TIMP-1, which preferentially inhibits MMP-1, was suppressed by 5 nM INFG. One µM PGF and 5 nM IFNG suppressed TIMP-2 mRNA expression. These results suggest a new role of MMPs: luteal MMPs stimulated by PGF and IFNG break down the extracellular matrix surrounding luteal cells, which accelerates detachment from the CL during luteolysis, providing an essential prerequisite for outflow of luteal cells from the CL to lymphatic vessels.

Cellular and functional characterization of buffalo (Bubalus bubalis) corpus luteum during the estrous cycle and pregnancy.

In the present paper, cellular composition of buffalo corpus luteum (CL) with its functional characterization based on 3ß-HSD and progesterone secretory ability at different stages of estrous cycle and pregnancy was studied. Buffalo uteri along with ovaries bearing CL were collected from the local slaughter house. These were classified into different stages of estrous cycle (Stage I, II, III and IV) and pregnancy (Stage I, II and III) based on morphological appearance of CL, surface follicles on the ovary and crown rump length of conceptus. Luteal cell population, progesterone content and steroidogenic properties were studied by dispersion of luteal cells using collagenase type I enzyme, RIA and 3ß-HSD activity, respectively. Large luteal cells (LLC) appeared as polyhedral or spherical in shape with a centrally placed large round nucleus and an abundance of cytoplasmic lipid droplets. However, small luteal cells (SLC) appeared to be spindle shaped with an eccentrically placed irregular nucleus and there was paucity of cytoplasmic lipid droplets. The size of SLC (range 12-23µm) and LLC (range 25-55µm) increased (P<0.01) with the advancement of stage of estrous cycle and pregnancy. The mean progesterone concentration per gram and per CL increased (P<0.01) from Stage I to III of estrous cycle with maximum concentration at Stage III of estrous cycle and pregnancy. The progesterone concentration decreased at Stage IV (day 17-20) of estrous cycle coinciding with CL regression. Total luteal cell number (LLC and SLC) also increased (P<0.01) from Stage I to III of estrous cycle and decreased (P<0.05), thereafter, at Stage IV indicating degeneration of luteal cells and regression of the CL. Total luteal cell population during pregnancy also increased (P<0.01) from Stage I to II and thereafter decreased (P>0.05) indicating cessation of mitosis. Increased (P<0.05) large luteal cell numbers from Stage I to III of estrous cycle and pregnancy coincided with the increased progesterone secretion and 3ß-HSD activity of CL. Thus, proportionate increases of large compared with small luteal cells were primarily responsible for increased progesterone secretion during the advanced stages of the estrous cycle and pregnancy. Total luteal cells and progesterone content per CL during the mid-luteal stage in buffalo as observed in the present study seem to be less than with cattle suggesting inherent luteal deficiency.

Embryo-luteal cells co-culture: an in vitro model to evaluate steroidogenic and prostanoid bovine early embryo-maternal interactions.

The role of progesterone (P(4)) and prostaglandins (PGs) in bovine early embryonic development and embryo-maternal crosstalk is almost unknown. Here, the in vitro steroidogenic (P(4)) and prostanoid (PGE(2) and PGF(2α)) interactions between bovine embryos and luteal cells (LC) were evaluated. In two experiments, embryos (n = 1.900) were either co-cultured with LC or cultured alone, from days 2 to 7 (day 0 = in vitro insemination). LC were also cultured alone, and medium was used as a control, all groups being cultured either with or without oil overlay of culture medium. Oil overlay of culture medium significantly decreased the amount of P(4), but not of PGE(2) and PGF(2α) measured in culture medium. Embryos and LC had transcripts of genes coding for enzymes of the PGs (PTGS2, PGES, and PGFS) and P(4) (StAR, P450scc, and 3ß-HSD) synthesis pathways, and produced P(4), PGF(2α), and PGE(2) into culture medium. Co-culture with LC exerted an embryotrophic effect, significantly increasing blastocyst yield and quality. This indicates a possible direct effect of LC in early embryo development. Embryos did not exert a luteotrophic effect upon LC. This may indicate that early embryos (until day 7) probably do not exert influence in LC main function. It is suggested that production of P(4), PGE(2), and PGF(2α) by early embryos may be associated to autocrine signaling leading to events in development and to paracrine signaling in the endometrium leading to local uterine receptivity.

Roles of prostaglandin F2alpha and hydrogen peroxide in the regulation of Copper/Zinc superoxide dismutase in bovine corpus luteum and luteal endothelial cells.

BACKGROUND: Prostaglandin F2alpha (PGF) induces luteolysis in cow by inducing a rapid reduction in progesterone production (functional luteolysis) followed by tissue degeneration (structural luteolysis). However the mechanisms of action of PGF remain unclear. Reactive oxygen species (ROS) play important roles in regulating the luteolytic action of PGF. The local concentration of ROS is controlled by superoxide dismutase (SOD), the main enzyme involved in the control of intraluteal ROS. Thus SOD seems to be involved in luteolysis process induced by PGF in cow. METHODS: To determine the dynamic relationship between PGF and ROS in bovine corpus luteum (CL) during luteolysis, we determined the time-dependent change of Copper/Zinc SOD (SOD1) in CL tissues after PGF treatment in vivo. We also investigated whether PGF and hydrogen peroxide (H2O2) modulates SOD1 expression and SOD activity in cultured bovine luteal endothelial cells (LECs) in vitro. RESULTS: Following administration of a luteolytic dose of PGF analogue (0 h) to cows at the mid-luteal stage, the expression of SOD1 mRNA and protein, and total SOD activity in CL tissues increased between 0.5 and 2 h, but fell below the initial (0 h) level at 24 h post-treatment. In cultured LECs, the expression of SOD1 mRNA was stimulated by PGF (1-10 microM) and H2O2 (10-100 microM) at 2 h (P<0.05). PGF and H2O2 increased SOD1 protein expression and total SOD activity at 2 h (P<0.05), whereas PGF and H2O2 inhibited SOD1 protein expressions and total SOD activity at 24 h (P<0.05). In addition, H2O2 stimulated PGF biosynthesis at 2 and 24 h in bovine LECs. Overall results indicate that, SOD is regulated by PGF and ROS in bovine LECs. SOD may play a role in controlling intraluteal PGF and ROS action during functional and structural luteolysis in cows.

Activation of PI3K/mTOR signaling pathway contributes to induction of vascular endothelial growth factor by hCG in bovine developing luteal cells.

We recently reported that HIF-1α plays a critical role in the regulation of vascular endothelial growth factor (VEGF) expression in the developing letual cells (LCs) and VEGF-dependent angiogenesis is essential for normal luteal development. Although it is believed that hypoxia is the primary inducer of VEGF, recent reports have also shown that human chorionic gonadotrophin (hCG) up-regulates VEGF expression in developing corpus luteum (CL). Therefore the present study was designed to test the induced effects of hCG on the expression of VEGF and HIF-1α in LCs under normoxic and hypoxic conditions. In addition, we also investigated whether the signaling pathways such as phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) are involved in hCG-induced VEGF in LCs. A significant increase of VEGF mRNA was found in LCs treated with hCG, which was consistent with the changes of HIF-1α protein, even under hypoxic conditions. However, there was no obvious changes of HIF-1α mRNA in hCG-treated LCs between normoxic and hypoxic conditions, indicating hCG induces VEGF expression by increasing transcription of HIF-1α, while hypoxia mainly increases HIF-1α protein stability. When LCs were pretreated with inhibitors, we found that the PI3K/mTOR signaling pathway is required for HIF-1α and VEGF expression induced by hCG, while the MAPK pathway is not required. Together, these results suggest that activation of IP3K/mTOR signaling pathway contributes to the induction of VEGF and HIF-1α in hCG-treated LCs. To our knowledge this will provide a new insight into the important mechanism of hCG/LH-induced VEGF-dependent angiogenesis in the bovine ovary.

Nitric oxide stimulates progesterone and prostaglandin E2 secretion as well as angiogenic activity in the equine corpus luteum.

Cytokines and nitric oxide (NO) are potential mediators of luteal development and maintenance, angiogenesis, and blood flow. The aim of this study was to evaluate (i) the localization and protein expression of endothelial and inducible nitric oxide synthases (eNOS and iNOS) in equine corpora lutea (CL) throughout the luteal phase and (ii) the effect of a nitric oxide donor (spermine NONOate, NONOate) on the production of progesterone (P4) and prostaglandin (PG) E(2) and factor(s) that stimulate endothelial cell proliferation using equine luteal explants. Luteal tissue was classified as corpora hemorrhagica (CH; n = 5), midluteal phase CL (mid-CL; n = 5) or late luteal phase CL (late CL; n = 5). Both eNOS and iNOS were localized in large luteal cells and endothelial cells throughout the luteal phase. The expression of eNOS was the lowest in mid-CL (P < 0.05) and the highest in late CL (P < 0.05). However, no change was found for iNOS expression. Luteal explants were cultured with no hormone added or with NONOate (10(-5) M), tumor necrosis factor-α (TNFα; 10 ng/mL; positive control), or equine LH (100 ng/mL; positive control). Conditioned media by luteal tissues were assayed for P4 and PGE(2) and for their ability to stimulate proliferation of bovine aortic endothelial cells (BAEC). All treatments stimulated release of P4 in CH, but not in mid-CL. TNFα and NONOate treatments also increased PGE(2) levels and BAEC proliferation in CH (P < 0.05). However, in mid-CL, no changes were observed, regardless of the treatments used. These data suggest that NO and TNFα stimulate equine CH secretory functions and the production of angiogenic factor(s). Furthermore, in mares, NO may play a role in CL growth during early luteal development, when vascular development is more intense.

DNA methylation is not involved in preovulatory down-regulation of CYP11A1, HSD3B1, and CYP19A1 in bovine follicles but may have a role in permanent silencing of CYP19A1 in large granulosa lutein cells.

The luteinizing hormone-induced morphological and physiological reorganization of the bovine follicle is preceded by a profound and well-orchestrated modulation of gene expression. In the present study, the cell type-specific methylation profiles of CYP11A1, HSD3B1, and CYP19A1, genes that encode key enzymes of steroid hormone biosynthesis, were analyzed to elucidate whether epigenetic parameters such as DNA methylation might be involved in gene regulation during luteinization. Transcript abundance and DNA methylation levels were determined in granulosa and theca of large dominant and late preovulatory follicles and in large granulosa lutein cells isolated from corpora lutea cyclica and graviditatis. Levels of the steroid hormones progesterone and estradiol-17beta were monitored to assess the physiological status of individual follicles. From our results, we conclude that (1) individual, even closely neighboring, CpG dinucleotides can show very different methylation levels; (2) proximal (<300 base pair [bp] from the respective transcription start sites) but not distal CpGs show cell type-specific methylation levels; (3) higher methylation levels suggestively preclude high levels of gene expression; (4) DNA methylation is not involved in the transient (HSD3B1 and CYP11A1) respectively permanent (CYP19A1) down-regulation of gene expression in late preovulatory follicles; and (5) DNA methylation may have a role in the permanent shutdown of promoter 2-directed CYP19A1 expression in large (granulosa derived) lutein cells.

Protein kinase C isoforms in the porcine corpus luteum: temporal and spatial expression patterns.

Porcine corpora lutea (CL) fail to show a luteolytic response to prostaglandin-F-2alpha (PGF-2alpha) (ie, luteolytic sensitivity, or LS) until approximately day 13 of the estrous cycle. In view of the importance of protein kinase C (PRKC) in PGF-2alpha signal transduction, it was hypothesized that limiting levels of 1 or more PRKC isoforms may explain the lack of LS before day 13. This hypothesis was tested by examining expression of mRNA and protein, and the cellular localization patterns of the 11 PRKC isoforms throughout the porcine estrous cycle, to determine whether PRKC expression correlates with and thus may be associated with the control of the acquisition of LS in the pig. The expression patterns show that for most PRKC isoforms (ie, PRKC alpha, beta 1, beta 2, delta, epsilon, theta, iota, and zeta), mRNA was maximally expressed on day 7 or day 10 (protein kinase D1 only) of the cycle, whereas PRKCs gamma, eta, and lambda were unchanged. At the protein level, only PRKC epsilon (PRKCE) significantly changed during the estrous cycle and was elevated on day 13 (versus days 4, 7, and 15; P<0.05). By immunofluoresence, most PRKC isoforms, including PRKCE, were localized to steroidogenic large luteal cells (LLC) and small (nonendothelial cell) luteal cell subtypes (SLC). In conclusion, since the increase in PRKCE protein expression (day 13) occurred coincidentally with the onset of LS (> or =day 12), these results support a potential role for PRKCE in control of the acquisition of LS in the pig.

Size distribution of luteal cells during pseudopregnancy in domestic cats.

Experiments were designed to investigate the size distribution of queen steroidogenic luteal cells throughout pseudopregnancy. Corpora lutea were obtained from the queens following ovariohysterectomy on days 7, 15 or 25 of pseudopregnancy. Luteal cells were isolated from the ovary by collagenase digestion. Steriodogenic cells were identified by staining of cells for 3beta-HSD activity. Cell diameters were measured using a microscope. Luteal cells having steroidogenic capacity covered a wide spectrum of sizes ranging from 3 to 35 mum in diameter. There was a significant increase in mean cell diameters (p < 0.01) as pseudopregnancy progressed. Mean diameter of 3beta-HSD positive cells increased from 10.41 +/- 0.7 microm, on day 7 of pseudopregnancy, to 19.72 +/- 1.3 microm on day 25 of pseudopregnancy. The ratio of large (>20 microm in diameter) to small (3-20 microm in diameter) luteal cells was 0.08 : 1.0 on day 7 of pseudopregnancy, with the 7.5-10 microm cell size class predominant. By day 25 of pseudopregnancy, the ratio of large-to-small cells was increased to 0.87 : 1.0, and 20-25 microm cell sizes become predominant. In conclusion, this study has demonstrated that the cells of the corpus luteum undergo continuous differentiation during pseudopregnancy in queen. This study also demonstrates that luteal cells dissociated from pseudopregnant queen can be used as a model to study the physiology of corpus luteum in pregnant cats.

Bisphenol A concentration-dependently increases human granulosa-lutein cell matrix metalloproteinase-9 (MMP-9) enzyme output.

Bisphenol A (BPA) is an estrogenic contaminant that has been quantified at higher levels in the follicular fluid of women with polycystic ovarian syndrome (PCOS) compared to healthy fertile controls. However, the effect of BPA on granulosa cell function is unknown. Therefore, the objective of the present study was to quantify the effect of BPA on granulosa cell progesterone (P4) output and matrix metalloproteinase (MMP)-2, and -9 output and activity. Granulosa-lutein cells (GLCs) were collected from women undergoing oocyte retrieval in an academic in vitro fertilization (IVF) program. Granulosa-lutein cells were treated with increasing log concentrations of BPA (1-10,000 ng/ml) or 17beta-estradiol (E2, 272 pg/ml or 1.0 nM) and treatment effects on MMP-2 and -9 activity and output, cell viability and cell proliferation were measured by commercial gelatin zymography, MMP-ELISA, MTS and BrdU incorporation assays, respectively. Granulosa-lutein cells in culture secrete MMP-2 and MMP-9. Bisphenol A treatment concentration-dependently increased MMP-9 output by GLCs with a maximal effect observed at 1000 ng/ml. Cell viability/proliferation was unaffected by BPA treatment at concentrations

Monoamine oxidase A is highly expressed by the human corpus luteum of pregnancy.

To investigate the physiological characteristics of the corpus luteum (CL) of pregnancy, we raised a mAb, human corpus luteum (HCL)-4, against human luteal cells obtained from CL of pregnancy. The affinity-purified antigen from human CL of pregnancy or placenta using HCL-4 was a 61 kDa protein. The partial amino acid sequence of the antigenic protein was identical to that of human monoamine oxidase A (MAOA, EC1.4.3.4). MAOA has been shown to catabolize catecholamines that were reported to regulate luteal function in CL and vasoconstriction in various organs. Immunohistochemistry using HCL-4 mAb showed that MAOA was intensely expressed on large luteal cells and moderately expressed on small luteal cells in the CL of pregnancy. In the CL of menstrual cycle, MAOA was weakly detected on large luteal cells but not detected at all on small luteal cells. Western blotting analysis confirmed the high expression of MAOA in CL of pregnancy. Northern blot analysis also showed the expression of MAOA mRNA in human CL, and showed that its expression was higher in CL of pregnancy than in CL of menstrual cycle. The increased expression of MAOA in the CL of pregnancy suggests the contribution of MAOA to the function of the CL of pregnancy.

Müllerian-inhibiting substance inhibits cytochrome P450 aromatase activity in human granulosa lutein cell culture.

OBJECTIVE: To investigate the effects of Müllerian-inhibiting substance (MIS) on cytochrome P450 aromatase (CYP19) gene expression in cultured human granulosa lutein cells (GLC). DESIGN: In vitro primary cell culture study. SETTING: Academic research laboratory and hospital-based fertility center. PATIENT(S): Eight normo-ovulatory patients undergoing IVF procedures due to male factor or tubal infertility. INTERVENTION(S): Serum and follicular fluid (FF) collected and stored at -80 degrees C until assayed. Granulosa lutein cells were harvested from follicular aspirates obtained during oocyte retrieval and cultured for 7 days with media in the presence or absence of MIS (10 ng/mL) or FSH 0.2 IU/mL. MAIN OUTCOME MEASURE(S): Serum and FF levels of E2 and MIS, and E2 production by GLC in culture. Levels of CYP19 mRNA in cultured GLC were determined by quantitative polymerase chain reaction (PCR) and CYP19 protein by Western blot. Statistical comparison used ANOVA and post hoc Tukey tests. RESULT(S): Follicle-stimulating hormone significantly increased E2 production in cultured GLC compared with control. The increase in E2 production is associated with higher levels of CYP19 mRNA and protein in GLC. The presence of MIS significantly inhibited FSH-induced E2 production, with concomitant reduction in CYP19mRNA and protein levels. CONCLUSION(S): Müllerian-inhibiting substance inhibits FSH augmentation of CYP19 enzyme activity and CYP19 gene expression in GLC. These findings may help to explain the association of high MIS levels and low FF E2 levels reported in women with polycystic ovary syndrome (PCOS).

Atrazine-induced changes in aromatase activity in estrogen sensitive target tissues.

Atrazine (ATR) is a pesticide used widely throughout North America. Although not directly estrogenic, ATR treatment has been shown to increase aromatase activity in tumor cell lines. Thus, it is suggested that ATR can increase local tissue estrogen levels in estrogen sensitive target tissues through increased aromatase activity. Therefore the effect of ATR on aromatase activity was measured in human granulosa-lutein cell cultures, cells that abundantly express aromatase, and endometrial stromal cell (ESC) cultures, cells that do not express aromatase. Aromatase activity was quantified by the tritiated water method and the specificity of the assay was confirmed by co-incubation with 4-hydroxyandrostenedione, an irreversible inhibitor of the catalytic activity of aromatase. Aromatase activity in ATR treated (1-10 microm) granulosa-lutein cells was increased more than 2-fold compared with control cultures. There were no treatment related changes in cellular protein and thus it is suggested that the ATR-induced change in aromatase activity was not due to an increase in cell number. ATR-treatment had no effect on ESC aromatase activity at any concentration tested. Similarly, there was no effect of ATR treatment on human recombinant aromatase activity in our cell-free test system. Therefore it is concluded that microm concentrations of ATR can increase aromatase activity of human granulosa cells but not ESC and this effect is not elicited at the enzyme level.

Size distribution of dispersed luteal cells during oestrous cycle in Angora goats.

The present study examines the size distribution of the goat steroidogenic luteal cells throughout the oestrous cycle. Corpora lutea (CL) were collected after laparatomy on days 5, 10 and 16 of the oestrous cycle. Luteal cells were isolated from CL by collagenase digestion. Steriodogenic luteal cells were identified by staining of the cells for 3beta-hydroxysteroid dehydrogenase activity, a marker for steroidogenic cells. Luteal cells having steroidogenic capacity covered a wide spectrum of sizes, ranging from 5 to 37.5 microm in diameter. There was a significant increase in mean cell diameters (p < 0.01) as CL aged. The mean cell diameter on day 5 was 11.55 +/- 0.12 microm, which was significantly increased and reached up to 19.18 +/- 0.24 mum by day 16 of the oestrous cycle. The ratio of large to small luteal cells was 0.06:1.0 on day 5 of the oestrous cycle. This ratio increased to 0.78:1.0 by day 16 of the oestrous cycle. Luteal cell size on days 5, 10 and 16 of the oestrous cycle reached its maximum at 7.5, 10 and 35 microm in diameter, respectively. Development of CL is associated with an increase in luteal cell size in goats. It is likely that small luteal cells could develop into large luteal cells as CL becomes older during oestrous cycle in goats.