NCBI Summary:
This gene encodes a cGMP-binding, cGMP-specific phosphodiesterase, a member of the cyclic nucleotide phosphodiesterase family. This phosphodiesterase specifically hydrolyzes cGMP to 5'-GMP. It is involved in the regulation of intracellular concentrations of cyclic nucleotides and is important for smooth muscle relaxation in the cardiovascular system. Alternative splicing of this gene results in three transcript variants encoding distinct isoforms. [provided by RefSeq, Jul 2008]
General function
Intracellular signaling cascade
Comment
Chronic treatment with Sildenafil has no effect on folliculogenesis or fertility in C57BL/6 and C57BL/6 knockout for iNOS mice. Donato MA et al. (2015) Sildenafil is an important phosphodiesterase inhibitor used to treat a range of diseases, including cardiovascular disease, prostatic hyperplasia and pulmonary hypertension. Its main mechanism of action is the inhibition of phosphodiesterase 5, leading to increased intracellular cyclic guanosine 3',5'-monophosphate. This second messenger plays an interesting role in the reproductive tract. The aim of the present study was to evaluate the effect of Sildenafil on folliculogenesis and fertility in mice. To do so, C57BL/6 wild-type mice and inducible nitric oxide synthase knockout (iNOS(-/-)) mice were treated with Sildenafil, and reproductive variables were evaluated. The treated and control animals underwent estrous cycle and fertility assay. Lipid profile, serum nitric oxide levels and the expression of endothelial nitric oxide synthase, inducible nitric oxide synthase and guanylate cyclase were evaluated. Additionally, ovaries were submitted to histological and morphological analysis. The findings demonstrated that chronic treatment with Sildenafil had no effect on folliculogenesis or fertility in C57BL/6 mice, suggesting that this drug can be safely used by women of childbearing age.//////////////////
Sildenafil Reduces Ischemia-Reperfusion Injury in Rat Ovary: Biochemical and Histopathological Evaluation. Celik M 2014 et al.
Background/Aims: To evaluate the effects of sildenafil on antioxidant enzyme activities, lipid peroxidation and histopathological changes in ovarian tissue after ischemia-reperfusion (I/R) injury in a rat model. Methods: A total of 18 adult female Wistar albino rats weighing 200-250 g were studied as follows: (1) control group: sham operation, (2) I/R group: 3 h of reperfusion after 3 h of ischemia and (3) I/R + sildenafil group: 3 h of reperfusion after 3 h of ischemia; half an hour before reperfusion, sildenafil (1.4 mg?kg(-1)) was given by oral gavage. At the end of the reperfusion periods, the ovarian tissues were removed for histopathological examination and to determine malondialdehyde (MDA) levels and glutathione peroxidase, myeloperoxidase (MPO) and superoxide dismutase (SOD) activities. Results: The I/R group had higher ovarian tissue MDA levels than the control group and the IR + sildenafil group (p = 0.016 and p = 0.044, respectively). MPO activity was lower in the IR + sildenafil group compared with the I/R group (p = 0.022). SOD activity was lower in the I/R group compared with the control group and the I/R + sildenafil group (p = 0.030 and p = 0.015, respectively). The I/R + sildenafil group had improved histological appearance which was not different to the control group (p > 0.05). Conclusion: The biochemical and histopathological results of this experimental study demonstrated that I/R injury in the ovary is ameliorated by sildenafil treatment. ? 2014 S. Karger AG, Basel.
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Cellular localization
Cytoplasmic
Comment
Ovarian function
Steroid metabolism, Oocyte maturation
Comment
The role of PDE5a in oocyte maturation of zebrafish. Li J et al. (2019) The importance of cyclic guanosine monophosphate (cGMP) signaling pathway in oocyte maturation has recently attracted much attention in vertebrates. Previously, using zebrafish as a model, we have revealed the role of cGMP and the action of cGMP protein kinase (PKG) in oocyte maturation. In the present study, the function of a cGMP specific phosphodiesterase (PDE5a) is further analyzed in oocyte maturation in zebrafish. Two distinct PDE5a coding genes (named PDE5aa and PDE5ab) were identified in zebrafish, and expressed in most adult tissues including ovary. Both pde5aa and pde5ab mRNA are predominantly expressed in the oocyte but not in follicular cells. Two commercial antibodies targeted to mammalian PDE5a and phosphorylated PDE5a were validated in zebrafish, and we found both antibodies can be used to detect PDE5ab and phosphorylated PDE5ab of zebrafish, respectively. Using both antibodies, we found PDE5ab is only expressed in the oocyte and the phosphorylation of PDE5ab in oocyte could be activated during oocyte maturation induced by human chronic gonadotropin. Intriguingly, we found that the oocyte maturation could be stimulated by treatment of either two different PDE5a inhibitors, sildenafil or tadalafil, and such effects could be completely blocked by a PKG inhibitor KT5823 and two gap junction blockers, respectively. All of these results clearly demonstrate the importance of PDE5a in maintaining the oocyte maturation of zebrafish. When compared with mammals, the functional model of PDE5a is different in zebrafish, suggesting the function of PDE5a might shift from the oocyte in fish to the granulosa cell in mammals during evolution.//////////////////
Luteinizing hormone signaling phosphorylates and activates the cyclic GMP phosphodiesterase PDE5 in mouse ovarian follicles, contributing an additional component to the hormonally induced decrease in cyclic GMP that reinitiates meiosis. Egbert JR et al. (2018) Prior to birth, oocytes within mammalian ovarian follicles initiate meiosis, but then arrest in prophase until puberty, when with each reproductive cycle, one or more follicles are stimulated by luteinizing hormone (LH) to resume meiosis in preparation for fertilization. Within preovulatory follicles, granulosa cells produce high levels of cGMP, which diffuses into the oocyte to maintain meiotic arrest. LH signaling restarts meiosis by rapidly lowering the levels of cGMP in the follicle and oocyte. Part of this decrease is mediated by the dephosphorylation and inactivation the NPR2 guanylyl cyclase in response to LH, but the mechanism for the remainder of the cGMP decrease is unknown. At least one cGMP phosphodiesterase, PDE5, is activated by LH signaling, which would contribute to lowering cGMP. PDE5 exhibits increased cGMP-hydrolytic activity when phosphorylated on serine 92, and we recently demonstrated that LH signaling phosphorylates PDE5 on this serine and increases its activity in rat follicles. To test the extent to which this mechanism contributes to the cGMP decrease that restarts meiosis, we generated a mouse line in which serine 92 was mutated to alanine (Pde5-S92A), such that it cannot be phosphorylated. Here we show that PDE5 phosphorylation is required for the LH-induced increase in cGMP-hydrolytic activity, but that this increase has only a modest effect on the LH-induced cGMP decrease in mouse follicles, and does not affect the timing of meiotic resumption. Though we show that the activation of PDE5 is among the mechanisms contributing to the cGMP decrease, these results suggest that another cGMP phosphodiesterase is also activated by LH signaling.//////////////////
Luteinizing Hormone Causes Phosphorylation and Activation of the cGMP Phosphodiesterase PDE5 in Rat Ovarian Follicles, Contributing, Together with PDE1 Activity, to the Resumption of Meiosis. Egbert JR et al. (2016) The meiotic cell cycle of mammalian oocytes in preovulatory follicles is held in prophase arrest by diffusion of cGMP from the surrounding granulosa cells into the oocyte. Luteinizing hormone (LH) then releases meiotic arrest by lowering cGMP in the granulosa cells. The LH-induced reduction of cGMP is caused in part by a decrease in guanylyl cyclase activity, but the observation that the cGMP phosphodiesterase PDE5 is phosphorylated during LH signaling suggests that an increase in PDE5 activity could also contribute. To investigate this idea, we measured cGMP-hydrolytic activity in rat ovarian follicles. Basal activity was due primarily to PDE1A and PDE5, and LH increased PDE5 activity. The increase in PDE5 activity was accompanied by phosphorylation of PDE5 at serine 92, a protein kinase A/G consensus site. Both the phosphorylation and the increase in activity were promoted by elevating cAMP and opposed by inhibiting protein kinase A, supporting the hypothesis that LH activates PDE5 by stimulating its phosphorylation by protein kinase A. Inhibition of PDE5 activity partially suppressed LH-induced meiotic resumption as indicated by nuclear envelope breakdown, but inhibition of both PDE5 and PDE1 activities was needed to completely inhibit this response. These results show that activities of both PDE5 and PDE1 contribute to the LH-induced resumption of meiosis in rat oocytes, and that phosphorylation and activation of PDE5 is a regulatory mechanism.//////////////////
The contribution of sildenafil (Viagra) to ovarian stimulation with gonadotropins in a woman with poor ovarian response. Trakakis E 2014 et al.
Abstract We aim to present the first case of a pregnancy achieved by administering sildenafil (Viagra) to a woman not responding to controlled ovarian hyperstimulation (COH) with the sole use of gonadotropins. A 37-year-old woman underwent COH, as part of an intracytoplasmic sperm injection (ICSI) cycle, with the combination of r-FSH and HMG for 13?d, without evidence of follicular growth. The addition of oral sildenafil at a dose of 50?mg per day for a total of five doses improved the ovarian response and resulted in the retrieval of 10 oocytes. Three embryos were transferred to the uterine cavity resulting in a successful pregnancy and, eventually, the delivery of a healthy neonate. Conclusively, the use of sildenafil as an adjunct to COH protocols may enhance ovarian response in a woman with poor ovarian response (POR) and merits further research.
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PDE5 modulates oocyte spontaneous maturation via cGMP-cAMP but not cGMP-PKG signaling. Wang S et al. Phosphodiesterase type 5 (PDE5), a cGMP specific, cGMP binding phosphodiesterase, specifically hydrolyzes cGMP to 5'-GMP. Here, we examine the distribution of PDE5 in mouse ovary and its effects on spontaneous maturation of mouse oocytes. PDE5 is present in oocytes and cumulus cells of big, antral follicles. Inhibition of activity of PDE5 significantly and reversibly inhibits spontaneous maturation of cumulus-oocyte complexes (COCs). Suppressive effect of PDE5 on spontaneous maturation of COCs is not blocked by the inhibitor of cGMP-dependent protein kinase (PKG). While Sildenafil, an inhibitor of PDE5, has a poor effect on cGMP levels, it significantly increases cAMP levels. These results suggest that the activity of PDE5 plays a role in regulating spontaneous maturation of mouse oocytes and imply that an interaction between cGMP and cAMP signal is involved in this process.
Resumption of meiosis induced by meiosis-activating sterol has a different signal transduction pathway than spontaneous resumption of meiosis in denuded mouse oocytes cultured in vitro. Faerge I et al. The sterol 4,4-dimethyl-5-cholesta-8,14,24-trien-3-ol (follicular fluid meiosis-activating sterol ;FF-MAS) isolated from human follicular fluid induces resumption of meiosis in mouse oocytes cultured in vitro. The purpose of this study was to examine the hypothesis that differential signal transduction mechanisms exist for FF-MAS-induced and spontaneous in vitro resumption of meiosis in mouse oocytes. Mouse oocytes were dissected from ovaries originating from mice primed with FSH 48 h before oocyte collection. Mechanically denuded germinal vesicle (GV) oocytes were in vitro matured in medium supplemented with hypoxanthine and FF-MAS or allowed to mature spontaneously; both groups were exposed to individual compounds known to inhibit specific targets in the cell. After 20-22 h of in vitro maturation, resumption of meiosis was assessed as the frequency of oocytes in GV breakdown (GVBD) stage. Pertussis toxin (2.5 microg/ml) did not influence resumption of meiosis in either group. Dibutyryl cyclic GMP (320 microM) inhibited FF-MAS-induced GVBD, but not spontaneous GVBD, whereas the subtype 5 phosphodiesterase-inhibitor zaprinast (50 microM) inhibited GVBD in both groups. Microinjection of the catalytic subunit of cAMP-dependent protein kinase into oocytes inhibited spontaneous GVBD, but not FF-MAS-induced GVBD. An inhibitor of cytoplasmic polyadenylation, cordycepin (80 microM), inhibited or retarded spontaneous GVBD to a further extent than it did FF-MAS-induced GVBD. Spontaneous GVBD was more sensitive to the histone H1 kinase-inhibitor olomoucine (250 microM) than was FF-MAS-induced GVBD. Addition of the mitogen-activated protein kinase (MAPK)-inhibitor PD 98059 (50 microM), phospholipase C-inhibitor U-73122 (10 microM), p21(ras)-inhibitor lovastatine (250 microM), and the src-like kinase inhibitor PP2 (20 microg/ml) inhibited FF-MAS-induced GVBD, but not spontaneous GVBD. Both MAPKs, extracellular regulated kinase (ERK) 1 and ERK2, were phosphorylated under FF-MAS-induced meiotic resumption, in contrast to spontaneous meiotic resumption, in which ERK1 and ERK2 phosphorylation occurred 2 h after GVBD. In the present study, we show that FF-MAS acts through an MAPK-dependent pathway, and we suggest that src-like kinase, p21(ras), and phosphoinositide signaling lie upstream of MAPK in the FF-MAS-activated signaling pathway. Clearly, striking pathway differences are present between spontaneous versus FF-MAS-induced meiotic resumption.
Follicle development and luteal cell morphology altered by phosphodiesterase-5 inhibitor. Donato MA et al. Vardenafil citrate is a potent vasodilator used in the treatment of patients with erectile dysfunction. Its mechanism of action is based on the selective inhibition of phosphodiesterase-5 (PDE5), specific to guanosine 3',5'-cyclic monophosphate (cGMP). Recently, chronic treatment with Vardenafil has been successfully used in cases of pulmonary hypertension and, despite being used in high doses for long periods, little is known about its effects on other systems. In the present study, female mice were treated daily with 5mg/kg Vardenafil for 4 weeks, after which the ovaries were collected for morphological analyses and sera were collected for biochemical assays. This study found that treatment with Vardenafil decreased HDL serum levels and the number of antral follicles as well as induced lesser lipid content in luteal cells, suggesting that high levels of cGMP may affect follicle development.////////
Expression regulated by
FSH, LH
Comment
Dephosphorylation and inactivation of NPR2 guanylyl cyclase in granulosa cells contributes to the LH-induced decrease in cGMP that causes resumption of meiosis in rat oocytes. Egbert JR 2014 et al.
In mammals, the meiotic cell cycle of oocytes starts during embryogenesis and then pauses. Much later, in preparation for fertilization, oocytes within preovulatory follicles resume meiosis in response to luteinizing hormone (LH). Before LH stimulation, the arrest is maintained by diffusion of cyclic (c)GMP into the oocyte from the surrounding granulosa cells, where it is produced by the guanylyl cyclase natriuretic peptide receptor 2 (NPR2). LH rapidly reduces the production of cGMP, but how this occurs is unknown. Here, using rat follicles, we show that within 10 min, LH signaling causes dephosphorylation and inactivation of NPR2 through a process that requires the activity of phosphoprotein phosphatase (PPP)-family members. The rapid dephosphorylation of NPR2 is accompanied by a rapid phosphorylation of the cGMP phosphodiesterase PDE5, an enzyme whose activity is increased upon phosphorylation. Later, levels of the NPR2 agonist C-type natriuretic peptide decrease in the follicle, and these sequential events contribute to the decrease in cGMP that causes meiosis to resume in the oocyte.
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Inhibitory action of cyclic guanosine 5'-phosphoric acid (GMP) on oocyte maturation: dependence on an intact cumulus. Hubbard CJ et al. Oocyte cumulus complexes (OCC) were isolated from antral follicles of proestrous hamsters prior to the luteinizing hormone (LH)/follicle-stimulating hormone (FSH) surge and then incubated from 4 to 24 h at 37 degrees C. Under these conditions approximately 89% of the oocytes exhibited metaphase plates (11% were in the dictyate stage) and addition of LH (200 ng/ml ovine NIH-LH-S20) did not significantly alter the percentage of oocyte maturation. Approximately 50% of the OCC incubated for 24 h with 6 mM 8-bromo-cyclic quanine 3':5' monophosphate (8-Br-cGMP) were prevented from maturing beyond the dictyate stage. OCC incubated with 6 mM 8-bromo-cyclic adenosine 3':5' monophosphate (8-Br-cAMP) were also prevented from maturing (59.5% 8-Br-cAMP) in vitro. LH (200 ng/ml) was able to overcome the 8-Br-cAMP-induced inhibition of oocyte maturation in OCC. It also produced a decrease in 8-Br-cGMP mediated inhibition which was more pronounced when the dosage of LH was increased to 10 microgram/ml. 8-Br-cGMP prevented oocyte maturation in a dose and time dependent manner. Only 8-Br-cAMP prevented maturation (approximately 60% inhibition) of denuded oocytes in vitro. Denuded oocytes incubated with and without 8-Br-cGMP exhibited no inhibited of maturation. These results indicate that 8-Br-cGMP may exert its inhibitory effects through the cumulus cells. On the other hand, cAMP appears to directly inhibit oocyte maturation.
Ovarian localization
Oocyte, Cumulus, Granulosa, Theca, Luteal cells
Comment
Up-regulation of cGMP-specific phosphodiesterase in the porcine cumulus-oocyte complex affects steroidogenesis during in vitro maturation. Sasseville M et al. The 3'5'-cyclic guanosine monophosphate (cGMP) pathway is known to influence ovarian functions, including steroidogenesis, ovulation, and granulosa cell proliferation. We show here that cGMP-phosphodiesterase activity increased in a gonadotropin-dependent manner more than 3-fold in the cumulus-oocyte complex (COC) after 24 hours of in vitro maturation and up to 5-fold after 48 hours. Further characterization of this increase demonstrated that the activity was located primarily in cumulus cells and was sensitive to sildenafil and zaprinast, two inhibitors specific to both type 5 and type 6 phosphodiesterases. Reverse transcription-PCR experiments showed that the mRNAs for cGMP-degrading phosphodiesterases 5A and 6C are present in the COC before and after 30 hours of in vitro maturation. Western blotting confirmed the presence of phosphodiesterase 5A in the COC. Western blotting of phosphodiesterase 6C revealed a significant up-regulation in the COC during in vitro maturation. Isolation and analysis of detergent-resistant membranes suggested that phosphodiesterase 6C protein, along with half of the total sildenafil-sensitive cGMP-degradation activity, is associated with detergent-resistant membrane in the COC after 30 hours of in vitro maturation. Treatment of porcine COC with sildenafil during in vitro maturation caused a significant decrease in gonadotropin-stimulated progesterone secretion. Together, these results constitute the first report exploring the contribution of cGMP-phosphodiesterase activity in mammalian COC, supporting a functional clustering of the enzyme, and providing the first evidence of its role in steroidogenesis.
Follicle stages
Preovulatory, Corpus luteum
Comment
Cyclic GMP Signaling Is Involved in the Luteinizing Hormone-Dependent Meiotic Maturation of Mouse Oocytes. Vaccari S et al. It is well established that cAMP signaling is an important regulator of the oocyte meiotic cell cycle. Conversely, the function of cGMP during oocyte maturation is less clear. Here, we evaluated the expression of cGMP-hydrolyzing phosphodiesterases (PDEs) in the somatic and germ cell compartments of the mouse ovarian follicle and demonstrate that PDE5 is preferentially expressed in somatic cells. Cyclic GMP is a potent inhibitor of cAMP hydrolysis from oocyte extracts with an IC50 of 97 nM. LH stimulation of cultured preovulatory follicles results in a marked decrease in cGMP content and a nadir is reached in 1.5 h; similarly, oocyte cGMP levels decrease after gonadotropin stimulation in vivo. The LH-dependent decrease in cGMP requires activation of the EGF network. Treatment of follicles with a PDE5 inhibitor increases cGMP in the follicle well above unstimulated levels. Although LH causes a decrease in cGMP in follicles preincubated with PDE5 inhibitors, the levels of this nucleotide remain above unstimulated levels. Under these conditions of elevated cGMP, LH stimulation does not cause oocyte maturation after 5 h of incubation. Microinjection of a cGMP-specific PDE into oocytes causes meiotic maturation of wild type oocytes, suggesting that an intra-oocyte pool of cGMP is involved in the maintenance of meiotic arrest. This effect is absent in PDE3A-deficient oocytes. Together, these findings provide evidence that cGMP and cAMP signaling cooperate in maintaining meiotic arrest via regulation of PDE3A, and that a decrease in cGMP in the somatic compartment is one of the signals contributing to meiotic maturation.