This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tai, C.-J. Articles by Leung, P. C. K. Search for Related Content PubMed PubMed Citation Articles by Tai, C.-J. Articles by Leung, P. C. K.

Role of Mitogen-Activated Protein Kinase in Prostaglandin F₂ Action in Human Granulosa-Luteal Cells¹

Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, British Columbia, Canada V6H 3V5; and Taipei Medical College Hospital (C.-R.T.), 110 Taipei, Taiwan

Address all correspondence and requests for reprints to: Dr. Peter C. K. Leung, Department of Obstetrics and Gynecology, University of British Columbia, Room 2H30, 4490 Oak Street, Vancouver, British Columbia, Canada V6H 3V5. E-.mail: peleung@interchange.ubc.ca.

	Abstract

Top Abstract Introduction >Materials and Methods Results Discussion References

 
In the ovary it has been demonstrated that PGF₂ activates the phospholipase C (PLC)/diacylglycerol/protein kinase C pathway. However, little is known about the downstream signaling events that mediate subsequent cellular responses such as steroidogenesis. The present study was designed to examine the effect of PGF₂ on activation of the mitogen-activated protein kinase (MAPK) signaling pathway and its physiological role in human granulosa-luteal cells (hGLCs). Human GLCs, obtained from women undergoing in vitro fertilization-embryo transfer, were treated with increasing concentrations of PGF₂ (10 nmol/L to 10 µmol/L) for 5 min. For time-course experiments, hGLCs were treated with 1 µmol/L PGF₂ for 1, 5, 10, or 20 min. Western blot analysis, using a monoclonal antibody that detected the phosphorylated forms of extracellular signal-regulated kinases 1 and 2 (p42^mapk and p44^mapk, respectively), demonstrated that PGF₂ activated MAPK in hGLCs in a dose- and time-dependent manner. Treatment of the cells with neomycin (10 mmol/L; a PLC inhibitor), bisindolylmaleimide I (5 µmol/L; a PKC inhibitor), or PD98059 (50 µmol/L; a MEK inhibitor and a MAPK kinase inhibitor) significantly attenuated the PGF₂-induced activation of MAPK. In contrast, MAPK activation was not significantly affected by pertussis toxin (200 ng/mL; a G_i inhibitor) pretreatment. To determine the role of MAPK in steroidogenesis, hGLCs were treated with PGF₂ (1 µmol/L), hCG (1 IU/mL), or PGF₂ plus hCG in the presence or absence of PD98059. Progesterone levels in the culture medium were examined by RIA. Treatment of hGLCs with PGF₂ significantly inhibited hCG-induced progesterone production. The presence of the MEK inhibitor, PD98059, reversed the inhibitory effect of PGF₂ on hCG-induced progesterone production. To our knowledge, it is the first demonstration of PGF₂-induced activation of the MAPK signaling pathway in the human ovary. These results indicated that PGF₂ activated MAPK subsequent to PLC and PKC activation through pertussis toxin-insensitive G protein in hGLCs. Further, we demonstrated that PGF₂-induced MAPK activation is associated with modulation of progesterone production. These results support the idea that the MAPK signaling pathway is involved in mediating PGF₂ actions in the human ovary.

	Introduction

Top Abstract Introduction >Materials and Methods Results Discussion References

 
PGF2 HAS BEEN implicated in the regression of the mammalian corpus luteum (1, 2, 3, 4). PGF₂ activates the phospholipase C (PLC)/diacylglycerol/protein kinase C (PKC) pathway to regulate ovarian function (5, 6, 7, 8, 9, 10). Through this signaling pathway, PGF₂ is capable of inhibiting gonadotropin-stimulated progesterone production (11).

Mitogen-activated protein kinases (MAPKs) are a group of serine-threonine kinases involved in converting extracellular stimuli to intracellular signals. Extracellular signal-regulated kinases (ERK), one of MAPKs subfamilies, are protein-serine/threonine kinases that are activated by extracellular agonists such as cytokines, growth factors, and neurotransmitters (12, 13). Two distinct classes of cell surface receptors, G protein-coupled receptor and receptor tyrosine kinases, have been shown to activate the MAPKs (14, 15, 16). When activated, ERK1 and ERK2 (also known as p42^mapk and p44^mapk, respectively), phosphorylate a variety of substrates, including nuclear transcript factors, which have been implicated in the control of cell proliferation and differentiation (17, 18, 19).

PGF₂ stimulates the MEK1/MAPK signaling cascade in bovine luteal cells (20). However, the physiological role of MAPK in luteal cells is still poorly understood. PGF₂ receptor has been reported to be expressed in human granulosa-luteal cells (hGLCs) (21), but little is known about the signaling events subsequent to the binding of PGF₂ to its receptor in hGLCs. In the present study the ability of PGF₂ to activate MAPK was investigated in cultured hGLCs. In addition, potential involvement of MAPK in PGF₂-induced antigonadotropic action was examined.

	>Materials and Methods

Top Abstract Introduction >Materials and Methods Results Discussion References

 
Reagents and materials

PGF₂, pertussis toxin (PTX), neomycin and hCG were obtained from Sigma (St. Louis, MO). Bisindolylmaleimide I, a PKC inhibitor, was obtained from Calbiochem (Cedarlane, Canada). PD98059, a MEK inhibitor, was purchased from New England Biolabs, Inc. (Beverly, MA). DMEM, penicillin-streptomycin, and FBS were obtained from Life Technologies, Inc. (Burlington, Canada). Bisindolylmaleimide I and PD98059 were dissolved in dimethylsulfoxide as suggested by the manufacturers.

Human GLC culture

Human GLCs were collected from patients undergoing an in vitro fertilization-embryo transfer program. The use of human GLCs was approved by the University of British Columbia clinical screening committee for research and other studies involving human subjects. Granulosa cells were separated from red blood cells in follicular aspirates by centrifugation through Ficoll-Paque, washed, and suspended in DMEM containing 100 U penicillin G/mL, 100 µg streptomycin/mL, and 10% FBS as described previously (10). The cells were plated at a density of approximately 150,000 cells in 35-mm culture dishes. The dishes were incubated at 37 C under a water-saturated atmosphere of 5% CO₂ in air for 3 days.

Treatments

Human GLCs were incubated in serum-free medium for 4 h before treatment. To examine the dose effect, hGLCs were treated with increasing concentrations of PGF₂ (10 nmol/L, 100 nmol/L, 1 µmol/L, or 10 µmol/L) for 5 min. For time-course experiments, hGLCs were treated with 1 µmol/L PGF₂ for 1, 5, 10, or 20 min.

To examine the intracellular signaling pathway subsequent to PGF₂ treatment, hGLCs were treated with PTX (200 ng/mL), neomycin (10 mmol/L; a PLC inhibitor), bisindolylmaleimide I (5 µmol/L; a PKC inhibitor), or PD98059 (50 µmol/L; a MEK inhibitor) in the presence or absence of PGF₂. In the present study hGLCs were pretreated with PTX for 1 h, with neomycin for 15 min, with bisindolylmaleimide I for 10 min, and with PD98059 for 1 h before PGF₂ treatment. The cells were collected 5 min after PGF₂ exposure.

Western blot analysis

The granulosa cells were washed with ice-cold PBS and incubated in 100 µL cell lysis buffer (150 mmol/L NaCl, 50 mmol/L Tris-HCl (pH 7.5), 1% Nonidet P-40, 0.5% deoxycholate, 0.1% SDS, 1.0 mmol/L phenylmethylsulfonylfluoride, 10 µg/mL leupeptin, and 100 µg/mL aprotinin) at 4 C for 30 min. The cell lysate was centrifuged at 10,000 x g for 5 min, and the supernatant was collected for Western blot analysis. The amount of protein was quantified using the Bio-Rad Laboratories, Inc., protein assay kit (Bio-Rad Laboratories, Inc., Richmond, CA) following the manufacturer’s protocol. Aliquots (30 µg) were subjected to 10% SDS-PAGE under reducing conditions, as previously described (22). The proteins were then electrophoretically transferred from the gels onto nitrocellulose membranes (Amersham Pharmacia Biotech, Ontario, Canada) according to the procedures of Towbin et al. (23). These nitrocellulose membranes were probed with a mouse monoclonal antibody directed against the phosphorylated forms of ERK1 and ERK2 (P-MAPK, p42^mapk and p44^mapk, respectively) at 4 C for 16 h. Alternatively, the membranes were probed with a rabbit polyclonal antibody for p42/p44 MAPK, which detected total MAPK (T-MAPK) levels (New England Biolabs, Inc.). After washing, these membranes were incubated with horseradish peroxidase-conjugated goat antimouse secondary antibody. The Amersham Pharmacia Biotech ECL system (Amersham Pharmacia Biotech) was used to detect the signal. Finally, these membranes were exposed to x-ray film (Kodak Omat x-ray film, Eastman Kodak Co., Rochester, NY). The autoradiograms were scanned with a laser densitometer (model 620 video densitometer, Bio-Rad Laboratories, Inc., Richmond, CA).

RIA

After culture in DMEM with 10% FBS for 3 days, hGLCs were incubated in DMEM with 5% FBS for 4 h before treatment for steroidogenesis experiments. To determine the role of MAPK in steroidogenesis, hGLCs were treated with PGF₂ (1 µmol/L), hCG (1 IU/mL), or PGF₂ plus hCG in the presence or absence of PD98059 for 24 h (24).

Progesterone levels in the culture medium were measured by established RIA (25). Antiprogesterone antibody was provided by Dr. D. T. Armstrong (University of Western Ontario). Briefly, samples were incubated with antibody and tracer, with a final concentration of 7000 cpm/mL of [1,2,6,7,16,17-³H]progesterone (Amersham Pharmacia Biotech). After incubation for 16–24 h, a charcoal/dextran solution was added to remove unbound progesterone or tracer. Scintillation cocktail (Amersham Pharmacia Biotech) was added to each sample, and the vials were counted with a ß-counter (LKB Wallac, Inc., Turku, Finland). The cells in each dish were harvested for quantifying protein amount using a protein assay kit (Bio-Rad Laboratories, Inc.). Samples were assayed in triplicate, and progesterone concentrations were standardized against total protein content.

hCG and MAPK in hGLCs

Gonadotropins have been demonstrated to activate MAPK in porcine granulosa cells (26). To examine the effect of hCG on MAPK activation, hGLCs were treated with 1 IU/mL hCG for 1, 5, 10, or 20 min, and cell lysates were collected for Western blot analysis. The effect of MAPK on hCG-stimulated progesterone production was studied by treating cells with 1 IU/mL hCG in the presence or absence of PD98059 for 24 h.

Statistical analysis

MAPK activity and progesterone levels were expressed as a relative ratio of basal levels. Data are shown as the mean ± SE. Statistical analysis was performed by one-way ANOVA followed by Tukey’s multiple comparison test. Differences were considered significant at P < 0.05.

	Results

Top Abstract Introduction >Materials and Methods Results Discussion References

 
Effects of PGF₂ on MAPK activation

To demonstrate the ability of PGF₂ in activating MAPK, hGLCs were treated with increasing concentrations (10 nmol/L to 10 µmol/L) of PGF₂ for 5 min. For time-course analysis, the cells were treated with 1 µmol/L PGF₂ for varying time intervals (1–20 min). As shown in Fig. 1, PGF₂ activated MAPK in hGLCs in a dose-dependent manner. A significant effect was observed at 100 nmol/L, and a maximum effect was noted at 10 µmol/L. PGF₂ was capable of rapidly inducing MAPK activity. A significant effect was seen 5 min after treatment (Fig. 2).

View larger version (29K): [in this window] [in a new window]   Figure 1. The dose-response of PGF2 to MAPK activation in hGLCs. Human GLCs were treated with increasing concentrations of PGF2 (0, 10 nmol/L, 100 nmol/L, 1 µmol/L, or 10 µmol/L) for 5 min as described in Materials and Methods. The activated MAPK was detected by Western blot analysis. The data were shown as relative ratio to basal levels. Values were presented as the mean ± SE of three individual experiments. Statistical analysis was performed by one-way ANOVA followed by Tukey’s test. Differences were considered significant at P < 0.05 (*).

View larger version (25K): [in this window] [in a new window]   Figure 2. The time course of PGF2 on MAPK activation in hGLCs. hGLCs were treated with 1 µmol/L PGF2 for 0, 1, 5, 10, or 20 min as described in Materials and Methods. The activated MAPK were detected by Western blot analysis. The data were shown as relative ratio to basal levels. Values were presented as the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05 (*).

PTX and PGF₂-induced MAPK activation

PGF₂ binds to a G protein-coupled transmembrane receptor in hGLCs (10). A PTX-insensitive G protein-coupled, G_q/11, is known to be expressed in hGLCs (10, 27). To identify the subclass of G protein involved in the PGF₂-induced activation of MAPK, human GLCs were pretreated with PTX for 1 h before exposure to PGF₂. In the present study pretreatment of PTX did not alter PGF₂-induced MAPK activity, indicating that PGF₂ acts through a PTX-insensitive G protein-coupled receptor (Fig. 3). Pretreatment with PTX for 24 h did not change the result, and PTX had no effect on PGF₂-induced MAPK activation up to 500 ng/mL (data not shown).

View larger version (25K): [in this window] [in a new window]   Figure 3. The effect of PTX on PGF2-induced MAPK activation in hGLCs. hGLCs were treated with 1 µmol/L PGF2 in the presence or absence of PTX (200 ng/mL) as described in Materials and Methods. The activated MAPK were detected by Western blot analysis. The data were shown as the relative ratio to basal levels. Values were presented as the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control; b, P < 0.05 vs. PGF2.

PLC and PGF₂-induced MAPK activation

Extracellular stimuli such as hormone, growth, and neurotransmitters cause the hydrolysis of phosphatidylinositol bisphosphate via the activation of PLC, resulting in the production of inositol triphosphate (IP3) and diacylglycerol (DAG). Neomycin, an aminoglycoside antibiotic, has been demonstrated to inhibit PLC (28). As shown in Fig. 4, treatment of hGLCs with 10 mmol/L neomycin significantly inhibited the PGF₂-induced activation of MAPK. PGF₂ activated MAPK to about 330% of the basal (control) level. The combined treatment with neomycin and PGF₂ significantly reduced MAPK activity by 80% compared with PGF₂ treatment alone.

View larger version (23K): [in this window] [in a new window]   Figure 4. The effect of neomycin, a PLC inhibitor, on PGF2-induced MAPK activation in hGLCs. hGLCs were treated with 1 µmol/L PGF2 in the presence or absence of neomycin (10 mmol/L) as described in Materials and Methods. The activated MAPK was detected by Western blot analysis. The data were shown as the relative ratio to basal levels. Values are the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control; b, P < 0.05 vs. PGF2.

PKC and PGF₂-induced MAPK activation

DAG alone or with cytosolic Ca²⁺, mobilized by IP3, plays a role in activating PKC. Bisindolylmaleimide I is a selective inhibitor of PKC (29). In this study bisindolylmaleimide I significantly attenuated the PGF₂-induced activation of MAPK (Fig. 5). Concomitant treatment with the PKC inhibitor and PGF₂ attenuated MAPK activation by 60% compared with the level stimulated by PGF₂ alone.

View larger version (29K): [in this window] [in a new window]   Figure 5. The effect of bisindolylmaleimide I, a PKC inhibitor (PKCI), on PGF2-induced MAPK activation in hGLCs. hGLCs were treated with 1 µmol/L PGF2 in the presence or absence of bisindolylmaleimide I (5 µmol/L) as described in Materials and Methods. The activated MAPK were detected by Western blot analysis. The data were shown as relative ratio to basal levels. Values are presented as the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control; b, P < 0.05 vs. PGF2.

MEK and PGF₂-induced MAPK activation

In MAPK activation cascade, MEK is the immediate activator of MAPK. MEK is also named MAPK kinase (13). In the present study it was shown that the MEK inhibitor, PD98059, significantly decreased the PGF₂-induced activation of MAPK in hGLCs (Fig. 6). Cotreatment with PD98059 and PGF₂ reduced MAPK activity to 15% of the level stimulated by PGF₂ alone.

View larger version (27K): [in this window] [in a new window]   Figure 6. The effect of PD98059, a MEK inhibitor (MEKI), on PGF2-induced MAPK activation in hGLCs. hGLCs were treated with 1 µmol/L PGF2 in the presence or absence of PD98059 (50 µmol/L) as described in Materials and Methods. The activated MAPK was detected by Western blot analysis. The data were shown as the relative ratio to basal levels. Values are the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control; b, P < 0.05 vs. PGF2.

Effects of PGF₂-evoked MAPK activation of hCG-induced progesterone production

To determine the role of MAPK in ovarian steroidogenesis, hGLCs were treated with PGF₂ (1 µmol/L), hCG (1 IU/mL), or PGF₂ plus hCG in the presence or absence of PD98059. As shown in Fig. 7 and 1 µmol/L PGF₂ had no effect on the basal level of progesterone production, whereas hCG increased progesterone production to 220% of the control value in hGLCs. Cotreatment of hGLCs with PGF₂ and hCG significantly inhibited progesterone production to 40% of the level induced by hCG. Further, the presence of the MEK inhibitor (PD98059) affected the inhibitory effect of PGF₂ on hCG-induced progesterone production.

View larger version (13K): [in this window] [in a new window]   Figure 7. The effect of MAPK on progesterone production in hGLCs. hGLCs were treated with PGF2 (1 µmol/L), hCG (1 IU/mL), or PGF2 plus hCG in the presence or absence of PD98059 for 24 h as described in Materials and Methods. Samples were assayed in triplicate, and progesterone concentrations were standardized against total protein content. Values are the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control; b, P < 0.05 vs. PGF2 plus hCG.

As shown in Fig. 8A, hCG was capable of activating MAPK in hGLCs in a time-dependent manner. Phosphorylated MAPK increased significantly in 1 min, compared with the control, and reached a maximum response after treatment with 1 IU/mL hCG for 5 min. To investigate the role of hCG-stimulated MAPK in steroidogenesis, hGLCs were treated with hCG in the presence or absence of MEK inhibitor. RIA demonstrated that there was no significant effect of MEKI on hCG-induced progesterone production (Fig. 8B).

View larger version (21K): [in this window] [in a new window]   Figure 8. A, The effect of hCG on MAPK activation in hGLCs. hGLCs were treated with 1 IU/mL hCG for various time (1–20 min) as described in Materials and Methods. The activated MAPK was detected by Western blot analysis. B, The effect of PD98059, a MEK inhibitor (MEKI), on hCG-induced progesterone production in hGLCs. Samples were assayed in triplicate, and progesterone concentrations were standardized against total protein content. Values are presented as the mean ± SE of three individual experiments. Differences were considered significant at P < 0.05. a, P < 0.05 vs. control.

	Discussion

Top Abstract Introduction >Materials and Methods Results Discussion References

2

2

2

The human ovary has been reported to produce PGF₂ (34), which has been suggested to mediate luteal regression in the mammalian ovary (3, 4). PGF₂ has been shown to inhibit LH- and hCG-induced progesterone production (11, 25). Several studies demonstrate that the luteolytic effect of PGF₂ is through increasing the production of endothelin-1, which, in turn, inhibits luteal steroidogenesis and induces the release of tumor necrosis factor-, a proapoptotic factor (35, 36, 37). In addition, tumor necrosis factor- was found to increase PGF₂ production in human granulosa cells (38). In the present study it was demonstrated that MAPK may mediate the inhibitory effect of PGF₂ on hCG-induced progesterone production.

After binding to transmembrane receptor, PGF₂ has been shown to activate phospholipase C through PTX-resistant G protein in hGLCs (10), resulting in the production of IP3 and DAG, which, in turn, activates PKC. In the present study PGF₂-induced phosphorylation of MAPK was not effected by 200 ng/mL PTX, implicating the involvement of a PTX-insensitive G protein such as G_q/11 (10). Both PLCß and PLC isoforms have been identified in hGLCs. Activation of the PGF₂ receptor has been reported to couple to PLCß (10). Neomycin has been demonstrated to inhibit all three isoforms of PLCs (28) and PGF₂-induced cellular responses such as vessel contraction (39). In the present study 10 mmol/L neomycin significantly attenuates the phosphorylated forms of MAPK, demonstrating the involvement of PLC in PGF₂-induced MAPK activation. In addition, PGF₂ has been reported to activate PKC and induce cytosolic calcium oscillations in human ovarian cells (8, 9). Via the activation of PKC, PGF₂ is known to exert antigonadotropic action by either reducing cAMP accumulation or stimulating cAMP phosphodiesterase (8, 11, 40). Bisindolylmaleimide is a selective inhibitor of PKC (29). In this study PGF₂-induced MAPK activation was significantly attenuated in hGLCs pretreated with this PKC inhibitor. MEK, also known as MAPK kinase (13), is an immediate activator of MAPK. In this study the presence of the MEK inhibitor, PD98059, significantly decreased the PGF₂-induced activation of MAPK. Taken together, the results of the present study clearly demonstrate the activation of the MAPK cascade by PGF₂ in hGLCs.

In hGLCs, the effect of PGF₂ on steroidogenesis is somewhat inconsistent (25, 41, 42). In this study 1 µmol/L PGF₂ had no effect on steroidogenesis in hGLCs. By contrast, treatment of hGLCs with PGF₂ significantly inhibited the progesterone production induced by hCG. The observation that PGF₂ inhibited gonadotropin-induced progesterone production has been shown previously (8, 11, 38). It has been proposed that the antigonadotropic action of PGF₂ is exerted via the inhibition of cAMP production. Further, PKC has been demonstrated to play a mediatory role in the inhibitory effect of PGF₂ on hCG-induced progesterone production in hGLCs (11). In the present study we demonstrated that the inhibitory effect of PGF₂ was reversed by MEK inhibitor, implicating a role of MAPK in the antigonadotropic action of PGF₂ in hGLCs. Oliver et al. reported that PD98059 (100 µmol/L) induced apoptosis in luteinized granulosa cells cultured in serum-free medium (43). We observed hGLCs to be viable and have no morphological change after 24-h treatment with PD98059 in DMEM supplemented with 5% FBS. The precise mechanism by which MAPKs affect ovarian steroid hormone is not clear. Several steroidogenic proteins or enzymes, such as steroidogenic acute regulatory protein, cytochrome P450 cholesterol side-chain cleavage, and 3ß-hydroxysteroid dehydrogenase, have been demonstrated in the human ovary (44, 45). Considering the nuclear translocation of activated MAPKs (7, 11, 12, 13), it can be postulated that MAPKs alter the activities and/or production of steroidogenic enzymes.

LH has been demonstrated to increase MAPK activity in porcine granulosa cells (26). In the present study hCG activated both ERK1 and ERK2 in a time-dependent manner. However, the hCG-induced MAPK did not alter hCG-stimulated progesterone production. Taken together, these observations support the idea that a diverse array of ligands, including hormones, neurotransmitters, and growth factors, are able to activate MAPK, and that cells may contain several MAPK signaling cascades, potentially regulated independently (30).

To our knowledge, it is the first demonstration of PGF₂-induced activation of the MAPK signaling pathway in the human ovary. Our data indicated that binding of PGF₂ to its receptor couples to a PTX-insensitive G protein-coupled, which subsequently leads to PLC, PKC, and MAPK activation. Further, we demonstrated that inhibition of MAPK activation reverses the effect of PGF₂ on progesterone production. These results support the hypothesis that the MAPK cascade is an integral part of the PGF₂ signal transduction system in the human ovary.

	Acknowledgments

 
We thank Dr. Margo Fluker and the Genesis Fertility Center (Vancouver, Canada) for the provision of human granulosa-luteal cells.

	Footnotes

 
¹ This work was supported by the Medical Research Council of Canada.

² Recipient of a studentship award from the British Columbia Research Institute for Children’s and Women’s Health.

³ Recipient of a career investigator award from the British Columbia Research Institute for Children’s and Women’s Health.

Received June 22, 2000.

Revised September 25, 2000.

Accepted October 3, 2000.

	References

Top Abstract Introduction >Materials and Methods Results Discussion References

 

1. Rothchild I. 1981 The regulation of the mammalian corpus luteum. Recent Prog Horm Res. 37:183–298.
2. Hansel W, Dowd JP. 1986 New concepts of the control of corpus luteum function. J Reprod Fertil. 78:755–768.[Abstract/Free Full Text]
3. Korda AR, Shutt DA, Smith ID, Shearman RP, Lyneham RC. 1975 Assessment of possible luteolytic effect on intra-ovarian injection of prostaglandin F₂ in the human. Prostaglandins. 9:443–449.[CrossRef][Medline]
4. Hanzen C. 1984 Prostaglandins and the physiology of human and animal reproduction. J Gynecol Obstet Biol Reprod (Paris). 13:351–361.[Medline]
5. Steele GL, Leung PCK. 1993 Mechanism of prostaglandin F₂ action in the ovary. J Lipid Mediat. 6:509–513.[Medline]
6. Leung PCK. 1985 Mechanisms of gonadotropin-releasing hormone and prostaglandin action on luteal cells. Can J Physiol Pharmacol 63:249–256.
7. Leung PCK, Minegishi T, Ma F, Zhou FZ, Ho-Yuen B. 1986 Induction of polyphosphoinositide breakdown in rat corpus luteum by prostaglandin F₂. Endocrinology. 119:12–18.[Abstract/Free Full Text]
8. Abayasekara DRE, Jones PM, Persaud SJ, Michael AE, Flint APF. 1993 Prostaglandin F₂ activates protein kinase C in human ovarian cells. Mol Cell Endocrinol. 91:51–57.[CrossRef][Medline]
9. Currie WD, Li W, Baimbridge KG, Yuen BH, Leung PCK. 1992 Cytosolic free calcium increased by prostaglandin F₂ (PGF₂), gonadotropin-releasing hormone, and angiotensin II in rat granulosa cells and PGF₂ in human granulosa cells. Endocrinology. 130:1837–1843.[Abstract/Free Full Text]
10. Carrasco MP, Asboth G, Phaneuf S, Lopez Bernal A. 1997 Activation of the prostaglandin FP receptor in human granulosa cells. J Reprod Fertil. 111:309–317.[Abstract/Free Full Text]
11. Abayasekara DR, Michael AE, Webley GE, Flint AP. 1993 Mode of action of prostaglandin F₂ in human luteinized granulosa cells: role of protein kinase C. Mol Cell Endocrinol. 97:81–91.[CrossRef][Medline]
12. Cobb MH, Goldsmith EJ. 1995 How MAP kinases are regulated. J Biol Chem. 270:14843–14846.[Free Full Text]
13. Fanger GR. 1999 Regulation of the MAPK family members: role of subcellular localization and architectural organization. Histol Histopathol. 14:887–894.[Medline]
14. Fantl WJ, Johnson DE, Williams LT. 1993 Signalling by receptor tyrosine kinases. Annu Rev Biochem. 62:453–481.[Medline]
15. Lopez-Ilasaca M. 1998 Signaling from G-protein-coupled receptors to mitogen-activated protein (MAP)-kinase cascades. Biochem Pharmacol. 56:269–277.[CrossRef][Medline]
16. Chabre O, Cornillon F, Bottari SP, Chambaz EM, Vilgrain I. 1995 Hormonal regulation of mitogen-activated protein kinase activity in bovine adrenocortical cells: cross-talk between phosphoinositides, adenosine 3',5'-monophosphate, and tyrosine kinase receptor pathways. Endocrinology. 136:956–964.[Abstract]
17. Post GR, Brown JH. 1996 G protein-coupled receptors and signaling pathways regulating growth responses. FASEB J. 10:741–749.[Abstract]
18. Cano E, Mahadevan LC. 1995 Parallel signal processing among mammalian MAPKs. Trends Biochem Sci. 20:117–122.[CrossRef][Medline]
19. Blenis J. 1993 Signal transduction via the MAP kinases: proceed at your own RSK. Proc Natl Acad Sci USA. 90:5889–5892.[Abstract/Free Full Text]
20. Chen DB, Westfall SD, Fong HW, Roberson MS, Davis JS. 1998 Prostaglandin F₂ stimulates the Raf/MEK1/mitogen-activated protein kinase signaling cascade in bovine luteal cells. Endocrinology. 139:3876–3885.[Abstract/Free Full Text]
21. Ristimaki A, Jaatinen R, Ritvos O. 1997 Regulation of PGF₂ receptor expression in cultured human granulosa-luteal cells. Endocrinology. 138:191–195.[Abstract/Free Full Text]
22. Laemmli UK. 1970 Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature227 :680–685.
23. Towbin H, Staehelin T, Gordon J. 1979 Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proc Natl Acad Sci USA. 76:4350–4354.[Abstract/Free Full Text]
24. Kang SK, Tai CJ, Cheng KW, Leung PCK. Gonadotropin-releasing hormone activates mitogen-activated protein kinase in human ovarian and placental cells. Mol Cell Endocrinol. In press.
25. Vaananen JE, Tong BLP, Vaananen CCM, Chan IHY, Yuen BH, Leung PCK. 1997 Interaction of prostaglandin PGF₂ and gonadotropin-releasing hormone on progesterone and estradiol production in human granulosa-luteal cells. Biol Reprod. 57:1346–1353.[Abstract]
26. Cameron MR, Foster JS, Bukovsky A, Wimalasena J. 1996 Activation of mitogen-activated protein kinases by gonadotropins and cyclic adenosine 5'-monophosphates in porcine granulosa cells. Biol Reprod. 55:111–119.[Abstract]
27. Lopez Bernal A, Bellinger J, Marshall J, Phaneuf S, Europe-Finner GN, Asboth G, Barlow DH. 1995 G-protein expression and second messenger formation in human granulosa cells. J Reprod Fertil. 104:77–83.[Abstract/Free Full Text]
28. Spath M, Woscholski R, Schachtele C. 1991 Characterization of multiple forms of phosphoinositide-specific pholpholipase C from bovine aorta. Cell Signal. 3:305–310.[CrossRef][Medline]
29. Toullec D, Pianetti P, Coste H, et al. 1991 The Bisindolylmaleimide GF 109203X is a potent and selective inhibitor of protein kinase C. J Biol Chem. 266:15771–15781.[Abstract/Free Full Text]
30. Van Biesen T, Luttrell LM, Hawes BE, Lefkowitz RJ. 1996 Mitogenic signaling via G protein-coupled receptors. Endocr Rev. 17:698–714.[Abstract/Free Full Text]
31. Boulton TG, Yancopoulos GD, Gregory JS, Slaughter C, Moomaw C, Hsu J, Cobb MH. 1990 An insulin-stimulated protein kinase similar to yeast kinases involved in cell cycle control. Science. 249:64–67.[Abstract/Free Full Text]
32. Boulton TG, Nye SH, Robbins DJ, et al. 1991 ERKs: a family of protein-serine/threonine kinases that are activated and tyrosine phosphorylated in response to insulin and NGF. Cell. 65:663–675.[CrossRef][Medline]
33. McNeill H, Puddefoot JR, Vinson GP. 1998 MAP kinase in the rat adrenal gland. Endocr Res. 24:373–380.[Medline]
34. Aksel S, Schomberg DW, Hammond CB. 1977 Progtaglandin F₂ production by the human ovary. Obstet Gynecol. 50:347–350.[Medline]
35. Girsh E, Milvae RA, Wang W, Meidan R. 1996 Effect of endothelin-1 on bovine luteal cell function: role in prostaglandin F₂-induced antisteroidogenic action. Endocrinology. 137:1306–1312.[Abstract]
36. Girsh E, Wang W, Mamluk R, Arditi F, Friedman A, Milvae RA, Meidan R. 1996 Regulation of endothelin-1 expression in the bovine corpus luteum: elevation by prostaglandin F₂. Endocrinology. 137:5191–5196.[Abstract]
37. Shikone T, Yamoto M, Kokawa K, Yamashita K, Nishimori K, Nnakano R. 1996 Apoptosis of human corpora lutea during cyclic luteal regression and early pregancy. J Clin Endocrinol Metab. 81:2376–2380.[Abstract]
38. Zolti M, Meirom R, Shemesh M, Wollach D, Mashiach S, Shore L, Rafael ZB. 1990 Granulosa cells as a source and target organ for tumor necrosis factor-. FEBS Lett. 261:253–255.[CrossRef][Medline]
39. Gergawy M, Vollrath B, Cook D. 1998 The mechanism by which aminoglycoside antibiotics cause vasodilation of canine cerebral arteries. Br J Pharmacol. 125:1150–1157.[CrossRef][Medline]
40. Michael AE, Webley GE. 1991 Prostaglandin F₂ stimulates cAMP phosphodiesterase via protein kinase C in cultured human granulosa cells. Mol Cell Endocrinol. 82:207–214.[CrossRef][Medline]
41. Vaananen JE, Lee S, Vaananen CCM, Yuen BH, Leung PCK. 1998 Stepwise activation of the gonadotropic signal transduction pathway, and the ability of prostaglandin F₂ to inhibit this activated pathway. Endocrine. 8:301–307.[CrossRef][Medline]
42. Khan-Dawood FS, Huang JC, Dawood MY. 1989 Effect of human chorionic gonadotropin and prostaglandin F₂ on progesterone production by human luteal cells. J steroid. Biochem 33: 941–947.
43. Oliver RH, Khan SM, Leung BS, Yeh J. 1999 Induction of apoptosis in luteinized granulosa cells by the MAP kinase kinase (MEK) inhibitor PD98059. Biochem Biophys Res Commun. 263:143–148.[CrossRef][Medline]
44. Duncan WC, Cowen GM, Illingworth PJ. 1999 Steroidogenic enzyme expression in human corpora lutea in the presence and absence of exogenous human chorionic gonadotrophin (HCG). Mol Hum Reprod. 5:291–298.[Abstract/Free Full Text]
45. Kiriakidou M, McAllister JM, Sugawara T, Strauss III JF. 1996 Expression of steroidogenic acute regulatory protein (StAR) in the human ovary. J Clin Endocrinol Metab. 81:4122–4128.[Abstract/Free Full Text]

This article has been cited by other articles:

				M. E Matzkin, S. I Gonzalez-Calvar, A. Mayerhofer, R. S Calandra, and M. B Frungieri Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F2{alpha} production in hamster Leydig cells Reproduction, July 1, 2009; 138(1): 163 - 175. [Abstract] [Full Text] [PDF]

				B. L Dozier, K. Watanabe, and D. M Duffy Two pathways for prostaglandin F2{alpha} synthesis by the primate periovulatory follicle Reproduction, July 1, 2008; 136(1): 53 - 63. [Abstract] [Full Text] [PDF]

				X. Hou, E. W. Arvisais, C. Jiang, D.-b. Chen, S. K. Roy, J. L. Pate, T. R. Hansen, B. R. Rueda, and J. S. Davis Prostaglandin F2{alpha} Stimulates the Expression and Secretion of Transforming Growth Factor B1 Via Induction of the Early Growth Response 1 Gene (EGR1) in the Bovine Corpus Luteum Mol. Endocrinol., February 1, 2008; 22(2): 403 - 414. [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]

				M. B. Frungieri, S. I. Gonzalez-Calvar, F. Parborell, M. Albrecht, A. Mayerhofer, and R. S. Calandra Cyclooxygenase-2 and Prostaglandin F2{alpha} in Syrian Hamster Leydig Cells: Inhibitory Role on Luteinizing Hormone/Human Chorionic Gonadotropin-Stimulated Testosterone Production Endocrinology, September 1, 2006; 147(9): 4476 - 4485. [Abstract] [Full Text] [PDF]

				P. R Manna, S. P Chandrala, Y. Jo, and D. M Stocco cAMP-independent signaling regulates steroidogenesis in mouse Leydig cells in the absence of StAR phosphorylation. J. Mol. Endocrinol., August 1, 2006; 37(1): 81 - 95. [Abstract] [Full Text] [PDF]

				P. R. Manna, S. P. Chandrala, S. R. King, Y. Jo, R. Counis, I. T. Huhtaniemi, and D. M. Stocco Molecular Mechanisms of Insulin-like Growth Factor-I Mediated Regulation of the Steroidogenic Acute Regulatory Protein in Mouse Leydig Cells Mol. Endocrinol., February 1, 2006; 20(2): 362 - 378. [Abstract] [Full Text] [PDF]

				J. A. MacLean II, M. K. Rao, K. M.H. Doyle, J. S. Richards, and M. F. Wilkinson Regulation of the Rhox5 Homeobox Gene in Primary Granulosa Cells: Preovulatory Expression and Dependence on SP1/SP3 and GABP Biol Reprod, December 1, 2005; 73(6): 1126 - 1134. [Abstract] [Full Text] [PDF]

				N. Martinelle, M. Holst, O. Soder, and K. Svechnikov Extracellular Signal-Regulated Kinases Are Involved in the Acute Activation of Steroidogenesis in Immature Rat Leydig Cells by Human Chorionic Gonadotropin Endocrinology, October 1, 2004; 145(10): 4629 - 4634. [Abstract] [Full Text] [PDF]

				G. Zhang and J. D. Veldhuis Insulin Drives Transcriptional Activity of the CYP17 Gene in Primary Culturesof Swine Theca Cells Biol Reprod, June 1, 2004; 70(6): 1600 - 1605. [Abstract] [Full Text] [PDF]

				R. Rusovici and H. A. LaVoie Expression and Distribution of AP-1 Transcription Factors in the Porcine Ovary Biol Reprod, July 1, 2003; 69(1): 64 - 74. [Abstract] [Full Text] [PDF]

				P. R. Manna, I. T. Huhtaniemi, X.-J. Wang, D. W. Eubank, and D. M. Stocco Mechanisms of Epidermal Growth Factor Signaling: Regulation of Steroid Biosynthesis and the Steroidogenic Acute Regulatory Protein in Mouse Leydig Tumor Cells Biol Reprod, November 1, 2002; 67(5): 1393 - 1404. [Abstract] [Full Text] [PDF]

				A.L. Johnson, E.V. Solovieva, and J.T. Bridgham Relationship Between Steroidogenic Acute Regulatory Protein Expression and Progesterone Production in Hen Granulosa Cells During Follicle Development Biol Reprod, October 1, 2002; 67(4): 1313 - 1320. [Abstract] [Full Text] [PDF]

				C. O. Stocco, L. F. Lau, and G. Gibori A Calcium/Calmodulin-dependent Activation of ERK1/2 Mediates JunD Phosphorylation and Induction of nur77 and 20alpha -hsd Genes by Prostaglandin F2alpha in Ovarian Cells J. Biol. Chem., January 25, 2002; 277(5): 3293 - 3302. [Abstract] [Full Text] [PDF]

				S. L. Gyles, C. J. Burns, B. J. Whitehouse, D. Sugden, P. J. Marsh, S. J. Persaud, and P. M. Jones ERKs Regulate Cyclic AMP-induced Steroid Synthesis through Transcription of the Steroidogenic Acute Regulatory (StAR) Gene J. Biol. Chem., September 7, 2001; 276(37): 34888 - 34895. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tai, C.-J. Articles by Leung, P. C. K. Search for Related Content PubMed PubMed Citation Articles by Tai, C.-J. Articles by Leung, P. C. K.