Phosphodiesterase 3A Inhibitor Research Articles

Anagrelide and idarubicin combination induces GSDME-mediated pyroptosis as a potential therapy for high-PDE3A acute myeloid leukemia.

Acute myeloid leukemia (AML) is an invasive hematopoietic malignancy requiring novel treatment strategies. In this study, we identified phosphodiesterase 3 A (PDE3A) as a potential new target for drug repositioning in AML. PDE3A was preferentially overexpressed in AML cells than in normal cells, and high expression of PDE3A was correlated with lower event-free survival (EFS) in de novo AML patients. The PDE3A inhibitor anagrelide (ANA) profoundly suppresses the proliferation of high PDE3A-expressing AML cells while exhibiting minimal impact on those with low PDE3A expression. Moreover, synergistic effect of ANA with other chemotherapeutic drugs in high PDE3A expression AML cells was observed. The ANA-idarubicin (IDA) combination showed the most remarkable synergistic effect among all ANA-chemotherapeutic drugs commonly used in AML cell line models. Mechanistically, the synergy between ANA and IDA inhibited the survival of PDE3Ahigh AML cell lines through pyroptosis. This mechanism was initiated by GSDME cleavage triggered by caspase-3 activation. In vivo combination treatment of leukemic animals with high PDE3A expression significantly reduced leukemia burden and prolonged survival time compared with single-drug and vehicle control treatments. Our findings suggest that combined ANA and IDA treatment is an innovative and promising therapeutic strategy for AML patients with high PDE3A expression.

Abstract A030: Treatment with sustained-release anagrelide reduces tumor volume and has antiproliferative effects in a patient-derived GIST xenograft mouse model

Abstract Anagrelide is a phosphodiesterase 3A inhibitor that is used to treat essential thrombocythemia. The drug stabilizes the interaction of PDE3A and Schlafen 12 (SLFN12), resulting in complex stabilization, activation of SLFN12 RNase activity and cytotoxic effects in cancer cells. Gastrointestinal stromal tumors (GIST) exhibit high levels of PDE3A expression compared to other cancers or healthy tissue. Orally administered anagrelide has shown antitumor effects in patient-derived GIST xenograft (PDX) mouse models. In this study, we investigated the efficacy of subcutaneously administered, sustained-release anagrelide in UZLX-GIST2B, a PDX mouse model characterized by a KIT mutation in exon 9 and typical dose-dependent imatinib sensitivity. We assessed changes in tumor volume and evaluated histological drug responses including hyalinization, fibrosis, myxoid generation, and tumor necrosis. Anagrelide was administered either orally (2.5 mg/kg, twice a day) or subcutaneously (35 mg/kg and 70 mg/kg, every fourth day) for a duration of 11 days. Treatments with both 35 mg/kg and 70 mg/kg doses resulted in a significant reduction in average tumor volume compared to untreated control mice (both doses 25% vs.129%, P < 0.001) or mice treated with oral anagrelide (25% vs. 61%, P =0 .08, P < 0.05, respectively). The histological response in tumor tissue was positively correlated with dose level, and tumors treated with the highest dose exhibited grade 3 to 4 responses in all cases. These results suggest that sustained-release anagrelide holds promise as a therapeutic option for the treatment of GIST. Further preclinical studies are warranted to investigate the pharmacokinetics and toxicity of this treatment approach. Citation Format: Kirsi Toivanen, Luna De Sutter, Agnieszka Wozniak, Tom Böhling, Patrick Schöffski, Harri Sihto. Treatment with sustained-release anagrelide reduces tumor volume and has antiproliferative effects in a patient-derived GIST xenograft mouse model [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A030.

Phosphodiesterase 3A Acts As a Tumor Activator and Its Inhibitor Anagrelide Combined with Idarubicin Represents a Potential Therapeutic Approach for PDE3A High Expressed Acute Myeloid Leukemia through Pyroptosis By Triggering Cleavage of Gasdermin E

Acute myeloid leukemia (AML) is a clinically aggressive and heterogeneous hematologic neoplasm with a poor overall outcome. Platelets can interact with malignant cells including leukemic blasts and play a crucial role in cancer progression, metastasis and angiogenesis, budding of platelet microparticles can transfer a plethora of bioactive molecules to cancer cells upon internalization and in AML this can induce chemoresistance. Anti-platelet therapy using Phosphodiesterase 3A (PDE3A) inhibitors, such as anagrelide (ANA), holds promise in tumor elimination. Additionally, upregulation of PDE3A in solid tumors is associated with a poor prognosis in patients and activates inflammatory pathways, impacting cancer cell stemness. However, the role of PDE3A in AML remains unclear. This study aims to investigate the correlation between PDE3A expression and AML prognosis, as well as to characterize the feasibility and mechanism of ANA as a potential anti-leukemia therapy and its synergistic effect to chemotherapeutic drugs. To explore the correlation between PDE3A expression and AML prognosis, we initially analyzed its expression in AML patients and healthy donors from the Children's Hospital of Soochow University. The results demonstrated significantly higher levels of PDE3A in bone marrow mononuclear cells (BMMNCs) from AML patients, both at the protein and mRNA levels, compared to BMMNCs from healthy donors. Subsequently, we investigated PDE3A expression and survival data of 152 AML patients from our center, revealing that patients with high PDE3A expression exhibited significantly lower overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS) compared to those with low PDE3A expression. These findings were further corroborated by data from other databases (R2 and GEPIA), confirming the significant role of PDE3A in AML. Among AML cell lines, HEL and MOLM-16 cells exhibited notably higher PDE3A expression at both the protein and mRNA levels, which were chosen for further study. ANA treatment specifically inhibited the proliferation of PDE3A-high-expressing AML cells but not low expression cells in vitro, which was further confirmed in the HEL-mediated xenograft leukemia model. Notably, the RNA sequencing data revealed ANA treatment significantly downregulated several chemotherapy-resistant genes, including PAK1, HMGCS1, p-SRC, DUSP16 and EGR1, indicating ANA has the potential to synergize with chemotherapeutic drugs for AML therapy. Therefore, we combine ANA and chemotherapy drugs to investigate the synergetic inhibitory effect. IDA with ANA simultaneously exerted the strongest synergistic effect among the six anti-leukemia drugs depend on the judgement of CI value and had the synergistic effect in HEL, MOLM-16 and primary cells from PDE3A high expressed AML patients. The GSEA analysis of RNA sequencing data showed that the IDA-ANA combination treatment led to a significant enrichment of the inflammatory response. Moreover, at the protein level, pyroptosis-related proteins including NLRP3, Cleaved-CASP3, Cleaved-CASP8 and GSDME-N were notably upregulated in IDA-ANA combination group compared to IDA or ANA group. Finally, we established an AML xenograft mouse model using the HEL cell line and administered different treatments: vehicle (control), IDA (0.5 mg/kg), ANA (5 mg/kg), or the indicated combination of IDA and ANA. The results demonstrated that the IDA-ANA combination treatment significantly extended the survival time of the mice and reduced the leukemia burden when compared to the individual treatments with either IDA or ANA. In second HEL xenograft mice study, separate cohorts of vehicle and drug treated mice were sacrificed and leukemic livers as well as spleens were harvested and weighed, the IDA-ANA combination treated mice exhibited smaller and lighter livers and spleens than the other groups and controls. HE results explained the histological decrease of HEL cells infiltration of IDA-ANA combination treatment in the livers, spleens and bone marrow compared with the treatment of IDA or ANA. Congruently, the analysis of IHC confirmed the same result. In summary, high expression of PDE3A related to poor prognosis in AML and PDE3A inhibitor ANA combined with IDA exerted anti-leukemia effect through pyroptosis on PDE3A high expressed AML. Our findings represent a potential therapeutic regimen for AML.

Anagrelide: A Clinically Effective cAMP Phosphodiesterase 3A Inhibitor with Molecular Glue Properties.

The mode of action by which the orphan drug anagrelide (1), a potent cAMP phosphodiesterase 3A inhibitor, reduces blood platelet count in humans is not well understood. Recent studies indicate that 1 stabilizes a complex between PDE3A and Schlafen 12, protecting it from degradation while activating its RNase activity.

Cilostamide, a phosphodiesterase 3A inhibitor, sustains meiotic arrest of rat oocytes by modulating cyclic adenosine monophosphate level and the key regulators of maturation promoting factor.

Cilostamide, a phosphodiesterase 3A (Pde3A) inhibitor, is known to increase intraoocyte cyclic adenosine monophosphate (cAMP) level which is involved in sustaining meiotic arrest of the oocytes. To explore the mechanisms involved in the cilostamide-mediated meiotic arrest of the oocytes, the present study describes the effects of cilostamide on cAMP level and related factors involved in maturation of the oocytes at its different meiotic stages; diplotene, metaphase I (MI) and metaphase II (MII). The oocytes from these three stages were collected from rat ovary and incubated with 10 µM cilostamide for 3 h in CO2 incubator. The levels of cAMP, cyclic guanosine monophosphate (cGMP) and the key players of maintaining meiotic arrest during oocyte maturation; Emi2, Apc, Cyclin B1, and Cdk1, were analyzed in diplotene, MI and MII stages. Pde3A was found to be expressed at all three stages but with the lowest level in MI oocyte. As compared to the control sets, the cAMP concentration was found to be highest in MII whereas cGMP was highest in the diplotene stage of cilostamide-treated group. The treated group showed declined reactive oxygen species level as compared with the control counterparts. Relatively increased levels of the Emi2, Cyclin B1, and phosphorylated thr161 of Cdk1 versus declined levels of phosphorylated thr14/tyr15 of Cdk1 in diplotene and MII stage oocytes are known to be involved in maintaining meiotic arrest and all these factors were found to undergo similar pattern of change due to the treatment with cilostamide. The findings thus suggest that cilostamide treatment promotes meiotic arrest by Pde3A inhibition led increase of both cAMP and cGMP level vis-a-vis modulation of the related regulatory factors such as Emi2, CyclinB1, and phosphorylated status of Cdk1 in diplotene and MII stage oocytes. Such a mechanism of meiotic arrest could allow the oocyte to prepare itself for meiotic maturation and thereby to improve oocyte quality.

TLR4/NF-κB/TNFα and cAMP/SIRT1 signaling cascade involved in mediating the dose-dependent effect of cilostazol in ovarian ischemia reperfusion-induced injury

Background One of the most dangerous gynecological emergencies is ovarian ischemia that commonly occurs during surgical manipulation or presence of ovarian masses. Objectives finding new therapies to prevent the associated harmful effects of ischemia/reperfusion-induced damage is still a critical need. For the first time, we aimed to evaluate the possible role of phosphodiesterase (PDE) 3 A inhibitor (PDEI), cilostazol (CLZ) in the treatment of ovarian ischemia reperfusion induced damage (OIR). Methods Rats were divided into five groups; sham, OIR group; CLZ (5, 10, 20 mg/kg) was given orally with induced OIR. Different biochemical parameters were detected such as total anti-oxidant capacity (TAC), reduced glutathione (GSH), malondialdehyde (MDA), cyclic adenosine monophosphate (cAMP), sirtuin1 (SIRT1), toll like receptor 4 (TLR4), nuclear factor kappa b (NF-κB) and tumor necrosis factor alpha (TNFα). In addition, histopathological features, ovarian weight changes and casapse3 immunoexpression were detected. Results Data revealed significant increase in ovarian weight changes, MDA, TLR4, TNFα, NF-κB and caspase 3 expressions in OIR induced group. Moreover, OIR group had histopathological features of ovarian damage with depletion of cAMP, SIRT1, TAC and GSH. Conclusion CLZ could ameliorate OIR-induced damage due to PDE inhibition, anti-oxidant, anti-inflammatory and anti-apoptotic properties with modulation of TLR4/NF-κB/TNFα and cAMP/SIRT1 signaling pathways.

Enhancing Oocyte Competence With Milrinone as a Phosphodiesterase 3A Inhibitor to Improve the Development of Porcine Cloned Embryos.

The objective of this study was to investigate the effect of milrinone supplementation as a phosphodiesterase 3A inhibitor during in vitro maturation (IVM) to coordinate the cytoplasmic and nuclear maturation of porcine oocytes and subsequent development of porcine cloned embryos. Brilliant cresyl blue (BCB)-stained (BCB +) oocytes, classified as well-developed, and BCB− oocytes were used in parthenogenesis (PA) and cloning, and their preimplantation development was compared. In PA embryos, BCB + oocytes had significantly higher rates of development than BCB− oocytes in terms of maturation (87.5 vs. 71.3%), cleavage (88.6 vs. 76.3%), and blastocyst development (34.3 vs. 25.3%) and also had higher cell numbers (46.9 vs. 38.9%), respectively (p < 0.05). In cloned embryos, the BCB + group also had a significantly higher blastocyst formation rate than the BCB− group (30.6 vs. 20.1%; p < 0.05). Supplementation with 75 μM milrinone during IVM of BCB− oocytes showed improvement in maturation and blastocyst development rates, which may be due to the coordinated maturation of the cytoplasm with the nucleus as an effect of milrinone. Moreover, the analysis of nuclear reprogramming via the examination of the expression levels of the reprogramming-related genes POU5F1, DPPA2, and NDP52IL in milrinone-supplemented BCB− oocytes showed higher expression levels than that in non-treated BCB− oocytes. These findings demonstrate that milrinone is useful in improving developmental competence in less competent oocytes during IVM and for proper nuclear reprogramming in the production of porcine cloned embryos by coordinating cytoplasmic and nucleus maturation.

A novel method for the collection of highly developmental murine immature oocytes

Isolation of germinal vesicle (GV) or metaphase I (MI) oocytes from large antral follicles, using a 30 gauge needle, in mice is a common method for the retrieval of immature oocytes from ovaries. However, this method depends entirely on the experience and judgment of the investigator. It is possible that not all of the isolated immature oocytes are from large antral follicles nor necessarily represent the cohort of oocytes that would be perfectly developed and consequently ovulated upon hormonal stimulation. Here, we administered an FDA approved phosphodiesterase 3A inhibitor, named cilostazol, in superovulated mice to result in the ovulation of GV or MI oocytes, depending on time and frequency of administration. The presented method results in mice ovulating GV or MI oocytes, which can be recovered from the oviduct without the investigator's judgment mentioned above. This method does not only result in immature oocytes with high yield, health, synchronized maturation, and competence levels but also is time and labor efficient. It also permits for physiological selections of a cohort of immature oocytes that would be entirely developed and eventually ovulated, as opposed to the conventional method.•Complete superovulation•Administration of cilostazol at different times•Recovery of ovulated immature oocytes from oviducts

A rapid and efficient method for the collection of highly developmental murine immature oocytes using cilostazol, a phosphodiesterase 3A inhibitor

AimsThe present study aims to define maturation, yield, health, and ease of collection of murine immature oocytes recovered using the conventional method or from mice treated with cilostazol. Main methodsThe conventional method included the superovulation of mice and the recovery of germinal vesicle (GV) or metaphase (MI) oocytes from preovulatory follicles. The cilostazol method included the oral treatment of superovulated mice with 7.5 mg cilostazol once or twice to result in the ovulation of MI or GV oocytes, respectively. Key findingsThe cilostazol method resulted in >95% of GV or MI oocytes with a diameter range of 60–90 μm or 50.1–70 μm in comparison to <60.0% of GV or MI oocytes resulting from the conventional method, respectively (P < 0.0001). The cilostazol method resulted in GV oocytes having higher levels of co-occurrence of peripheral cortical granules (CG) and chromatin configuration of surrounded nucleolus and MI oocytes having higher levels of co-occurrence of normally organized spindles/chromosomes and peripheral CG with free domains than did the conventional method (P < 0.001). The cilostazol method was more time and labor efficient and resulted in higher oocyte yields of normal morphology than did the conventional method (P < 0.01). SignificanceThe presented method provides not only oocytes with uniform size and synchronized developmental maturation but also a technique of oocyte collection that is efficient and resourceful. It is possible that not all immature oocytes resulting from the conventional method are from preovulatory follicles nor have been developed adequately and consequently ovulated as opposed to the presented method.

Docking and quantitative structure-activity relationship of bi-cyclic heteroaromatic pyridazinone and pyrazolone derivatives as phosphodiesterase 3A (PDE3A) inhibitors.

PDE3s belong to the phosphodiesterases family, where the PDE3A isoform is the major subtype in platelets involved in the cAMP regulation pathway of platelet aggregation. PDE3A inhibitors have been designed as potential antiplatelet agents. In this work, a homology model of PDE3A was developed and used to obtain the binding modes of bicyclic heteroaromatic pyridazinones and pyrazolones. Most of the studied compounds adopted similar orientations within the PDE3A active site, establishing hydrogen bonds with catalytic amino acids. Besides, the structure-activity relationship of the studied inhibitors was described by using a field-based 3D-QSAR method. Different structure alignment strategies were employed, including template-based and docking-based alignments. Adequate correlation models were obtained according to internal and external validations. In general, QSAR models revealed that steric and hydrophobic fields describe the different inhibitory activities of the compounds, where the hydrogen bond donor and acceptor fields have minor contributions. It should be stressed that structural elements of PDE3A inhibitors are reported here, through descriptions of their binding interactions and their differential affinities. In this sense, the present results could be useful in the future design of more specific and potent PDE3A inhibitors that may be used for the treatment of cardiovascular diseases.

Improvements in oocyte competence in superovulated mice following treatment with cilostazol: Ovulation of immature oocytes with high developmental rates

Exogenous administration of superovulatory hormones negatively affects oocyte competence in mammals. Phosphodiesterase 3A inhibitors were found to improve competence of oocytes matured in vitro in several species, including humans. This study was therefore designed to define oocyte maturation synchronization and competence, in vivo, using superovulated mice treated with cilostazol, a selective phosphodiesterase 3A inhibitor. Swiss Webster mice were superovulated and treated orally with 7.5mg cilostazol once or twice to result in ovulation of immature oocytes at the metaphase I (MI) or germinal vesicle (GV) stage, respectively. Control immature oocytes were recovered from preovulatory follicles of superovulated mice not treated with cilostazol. Treated GV oocytes had significantly higher rates of synchronized and advanced chromatin configuration and cortical granule distribution than did control GV oocytes. Treated GV oocytes had a moderate increase in cAMP levels and consequently higher rates of meiotic maturation, IVF, and blastocyst formation than did control GV oocytes (P<0.0001). Treated MI oocytes had higher rates of normal spindles and chromosomes aligned at the metaphase plate than did control MI oocytes (P<0.003). Treated mice ovulating MI oocytes produced litter sizes larger than those observed in control mice ovulating mature oocytes (P<0.002). This study reveals that synchronization of oocyte maturation in superovulated mice improves oocyte development and competence. The capability of cilostazol, a clinically approved medication, to improve mouse oocyte competence suggests the potential benefit of including this compound in ovarian hyperstimulation programs to improve in vitro fertilization outcomes in infertile women.

65 OVULATION OF IMMATURE OOCYTES WITH HIGH COMPETENCE RATES

Collection of immature oocytes from antral follicles in superovulated mice is a widely established technique for retrieval of germinal vesicle (GV) and metaphase I (MI) oocytes. Investigators use their experience to select antral follicles under a microscope before puncturing the follicles. This is sometimes followed by screening of oocytes based on morphology and diameter, and usually mouse oocytes of small diameters or abnormal morphologies are excluded. Shortcomings with the current technique may include varied oocyte yields and collection of oocytes from primary and secondary follicles. Moreover, such immature oocytes were observed to have different chromatin configurations, cortical granule distributions, spindle-chromosome organizations, fertilization rates, and diameters. This study was designed to investigate the potential of ovulated immature oocytes, resultant from superovulated mice treated with an FDA approved phosphodiesterase 3A inhibitor named cilostazol (CLZ), to substitute for ovarian immature oocytes collected from antral follicles of superovulated mice. Swiss Webster mice were superovulated and gavaged with 7.5 mg of CLZ once, at the same time as hCG injection, or twice, at the same time as hCG plus 6 h post-hCG injection, to result in ovulation of MI or GV oocytes, respectively. Control ovarian GV or MI oocytes were collected from ovarian antral follicles of superovulated mice not treated with CLZ. Ten mice were used in each treatment or control group. Single or multiple administrations of CLZ resulted in mice ovulating 85.8 ± 3.9% MI oocytes or 95.2 ± 3% GV oocytes (mean ± SEM), respectively. Treated GV oocytes had significantly higher rates of advanced chromatin configuration and cortical granule distribution than did control GV oocytes. Treated GV oocytes had lower cAMP levels and higher rates of meiotic maturation, IVF, and blastocyst formation than did control GV oocytes (P &lt; 0.0001). Treated MI oocytes had significantly higher rates of normal spindle and chromosomes aligned at the metaphase plates and offspring than did control MI oocytes. Control or treated GV oocytes were found to have greater diameters than did control or treated MI oocytes, respectively (P &lt; 0.007), indicating that initiation of meiotic maturation is associated with reduction in oocyte diameters and utilisation of cytoplasm proteins and cofactors. Moreover, control GV oocytes were found to have greater diameters than did treated GV oocytes (P = 0.007). This may refer to the readiness of treated GV oocytes to undergo germinal vesicle breakdown and transition into the MI stage, especially treated GV oocytes had high rates of meiotic development in comparison to control GV oocytes. Diameters of GV nuclei in treated GV oocytes were smaller than those in control GV oocytes (P = 0.006), which may also indicate a germinal vesicle that had started to undergo germinal vesicle breakdown. A similar significant difference was also noted with control and treated MI oocytes. In summary, we present a novel method for retrieval of immature oocytes at different stages of meiotic maturation. Treated ovulated immature oocytes had more uniform diameters and high developmental competence than did ovarian immature oocytes. Treated ovulated immature oocytes may substitute for ovarian immature oocytes and become an additional research resource.

Clinical effects of phosphodiesterase 3A mutations in inherited hypertension with brachydactyly.

Autosomal-dominant hypertension with brachydactyly is a salt-independent Mendelian syndrome caused by activating mutations in the gene encoding phosphodiesterase 3A. These mutations increase the protein kinase A-mediated phosphorylation of phosphodiesterase 3A resulting in enhanced cAMP-hydrolytic affinity and accelerated cell proliferation. The phosphorylated vasodilator-stimulated phosphoprotein is diminished, and parathyroid hormone-related peptide is dysregulated, potentially accounting for all phenotypic features. Untreated patients die prematurely of stroke; however, hypertension-induced target-organ damage is otherwise hardly apparent. We conducted clinical studies of vascular function, cardiac functional imaging, platelet function in affected and nonaffected persons, and cell-based assays. Large-vessel and cardiac functions indeed seem to be preserved. The platelet studies showed normal platelet function. Cell-based studies demonstrated that available phosphodiesterase 3A inhibitors suppress the mutant isoforms. However, increasing cGMP to indirectly inhibit the enzyme seemed to have particular use. Our results shed more light on phosphodiesterase 3A activation and could be relevant to the treatment of severe hypertension in the general population.

Regulation of Sarcoplasmic Reticulum Ca2+ ATPase 2 (SERCA2) Activity by Phosphodiesterase 3A (PDE3A) in Human Myocardium: PHOSPHORYLATION-DEPENDENT INTERACTION OF PDE3A1 WITH SERCA2

Cyclic nucleotide phosphodiesterase 3A (PDE3) regulates cAMP-mediated signaling in the heart, and PDE3 inhibitors augment contractility in patients with heart failure. Studies in mice showed that PDE3A, not PDE3B, is the subfamily responsible for these inotropic effects and that murine PDE3A1 associates with sarcoplasmic reticulum Ca(2+) ATPase 2 (SERCA2), phospholamban (PLB), and AKAP18 in a multiprotein signalosome in human sarcoplasmic reticulum (SR). Immunohistochemical staining demonstrated that PDE3A co-localizes in Z-bands of human cardiac myocytes with desmin, SERCA2, PLB, and AKAP18. In human SR fractions, cAMP increased PLB phosphorylation and SERCA2 activity; this was potentiated by PDE3 inhibition but not by PDE4 inhibition. During gel filtration chromatography of solubilized SR membranes, PDE3 activity was recovered in distinct high molecular weight (HMW) and low molecular weight (LMW) peaks. HMW peaks contained PDE3A1 and PDE3A2, whereas LMW peaks contained PDE3A1, PDE3A2, and PDE3A3. Western blotting showed that endogenous HMW PDE3A1 was the principal PKA-phosphorylated isoform. Phosphorylation of endogenous PDE3A by rPKAc increased cAMP-hydrolytic activity, correlated with shift of PDE3A from LMW to HMW peaks, and increased co-immunoprecipitation of SERCA2, cav3, PKA regulatory subunit (PKARII), PP2A, and AKAP18 with PDE3A. In experiments with recombinant proteins, phosphorylation of recombinant human PDE3A isoforms by recombinant PKA catalytic subunit increased co-immunoprecipitation with rSERCA2 and rat rAKAP18 (recombinant AKAP18). Deletion of the recombinant human PDE3A1/PDE3A2 N terminus blocked interactions with recombinant SERCA2. Serine-to-alanine substitutions identified Ser-292/Ser-293, a site unique to human PDE3A1, as the principal site regulating its interaction with SERCA2. These results indicate that phosphorylation of human PDE3A1 at a PKA site in its unique N-terminal extension promotes its incorporation into SERCA2/AKAP18 signalosomes, where it regulates a discrete cAMP pool that controls contractility by modulating phosphorylation-dependent protein-protein interactions, PLB phosphorylation, and SERCA2 activity.

Improvement in in vitro fertilization outcome following in vivo synchronization of oocyte maturation in mice.

Synchronization of oocyte maturation in vitro has been shown to produce higher in vitro fertilization (IVF) rates than those observed in oocytes matured in vitro without synchronization. However, the increased IVF rates never exceeded those observed in oocytes matured in vivo without synchronization. This study was therefore designed to define the effect of in vivo synchronization of oocyte maturation on IVF rates. Mice were superovulated and orally treated with 7.5 mg cilostazol (CLZ), a phosphodiesterase 3A (PDE3A) inhibitor, to induce ovulation of immature oocytes at different stages depending on frequency and time of administration of CLZ. Mice treated with CLZ ovulated germinal vesicle (GV) or metaphase I (MI) oocytes that underwent maturation in vitro or in vivo (i.e. in the oviduct) followed by IVF. Superovulated control mice ovulated mature oocytes that underwent IVF directly upon collection. Ovulated MI oocytes matured in vitro or in vivo had similar maturation rates but significantly higher IVF rates, 2-4 cell embryos, than those observed in control oocytes. Ovulated GV oocytes matured in vitro showed similar maturation rates but significantly higher IVF rates than those observed in control oocytes. However, ovulated GV oocytes matured in vivo had significantly lower IVF rates than those noted in control oocytes. It is concluded that CLZ is able to synchronize oocyte maturation and improve IVF rates in superovulated mice. CLZ may be capable of showing similar effects in humans, especially since temporal arrest of human oocyte maturation with other PDE3A inhibitors in vitro was found to improve oocyte competence level. The capability of a clinically approved PDE3A inhibitor to improve oocyte fertilization rates in mice at doses extrapolated from human therapeutic doses suggests the potential scenario of the inclusion of CLZ in superovulation programs. This may improve IVF outcomes in infertile patients.

In vitro effects of cilostazol, a phosphodiesterase 3A inhibitor, on mouse oocyte maturation and morphology

Inhibition of phosphodiesterase 3A (PDE3A) in oocytes has been reported to arrest oocyte maturation and to increase intra-oocyte cyclic adenosine monophosphate levels. Although many PDE3A inhibitors have been found to arrest oocyte maturation in different species, including humans, the most commonly prescribed PDE3A inhibitor named cilostazol (CLZ) has not yet been fully evaluated in reproduction. The present study was designed to investigate the potential inhibitory effects of CLZ on oocyte maturation and morphology in vitro. Antral oocytes were recovered from hyperstimulated mice and allocated to 10 different CLZ concentrations (0.00-67.66 μmol/L). Oocytes were then assessed after 24 and 48 h of incubation for maturation and morphology. Some of the evaluated CLZ concentrations (1.06-4.23 μmol/L) were made similar to those observed in human clinical trials. CLZ arrested oocyte maturation at the germinal vesicle (GV) stage at concentrations as low as 1.06 μmol/L (P < 0.0001). A selective degenerative impact of CLZ targeting arrested oocytes at the GV stage was observed during 24 h of incubation (r = -0.781, P < 0.0001). This was not the case with non-arrested oocytes (r = -0.082, P = 0.64). Such degenerative impact was dose-dependent (P < 0.0001), suggesting a role for cyclic adenosine monophosphate in this degenerative process. The degenerated oocytes were of distorted oolema or fragmented cytoplasm. Based on the experiments, it is concluded that CLZ can inhibit oocyte maturation in vitro, at concentrations similar to those observed in humans taking CLZ, and under such conditions the prolonged maintenance of oocytes at the GV stage is harmful.

Caption: Oocyte morphology after 24 h and 48 h of incubation with phosphodiesterase 3A inhibitor. (See 147–153 by AM Taiyeb, et al.)

Cover Image: Use Fig.4 from CEP 12193 Clinical tests for intestinal permeability: ‘Sweet’ transition from clinical to basic physiology Gut permeability to saccharidic probes Pioglitazone and irritable bowel syndrome Muscarinic receptor interaction

Cilostazol administered to female mice induces ovulation of immature oocytes: A contraceptive animal model

AimsBoth Cilostamide and Org 9935 are phosphodiesterase 3A (PDE3A) inhibitors that were evaluated in rodents and monkeys for their non-steroidal contraceptive properties. Although both compounds inhibited oocyte maturation, an adverse effect on heart rate was observed. Cilostazol (CLZ, Pletal®) is a safe PDE3A inhibitor that was recently reported to block pregnancy in naturally cycling mice. In this study, the dose, frequency, time of administration, and reversibility effects of CLZ on oocyte maturation were defined using superovulated mice. Main methodsSuperovulated mice were gavaged once or twice with 0, 7.5, or 15mg CLZ at various times around the ovulatory stimulus. Ovulated oocytes were then evaluated for maturational stages. Key findingsCLZ resulted in mice ovulating significant numbers of immature oocytes when administered anytime between 9h before the ovulatory stimulus and 2h after the stimulus. This inhibitory effect was greater when CLZ dose was increased, administered twice or closer to the time of the ovulatory stimulus. Conversely, ovulated immature oocytes resumed maturation in oviducts when CLZ dose was reduced, administered once and away from the time of the stimulus. SignificanceControlling CLZ dose, frequency, and time of administration produced mice ovulating immature oocytes at different stages, which may be an advantage over the conventional collection of immature oocytes from ovaries. More importantly, the capability of a clinically approved PDE3A inhibitor, with a reasonable margin of safety, to arrest oocyte maturation over a wide range of administration times and at doses extrapolated from human therapeutic doses demonstrates the contraceptive capacity of CLZ.

Zinc Depletion Causes Multiple Defects in Ovarian Function during the Periovulatory Period in Mice

Shortly before ovulation, the oocyte acquires developmental competence and granulosa cells undergo tremendous changes including cumulus expansion and luteinization. Zinc is emerging as a key regulator of meiosis in vitro, but a complete understanding of zinc-mediated effects during the periovulatory period is lacking. The present study uncovers the previously unknown role of zinc in maintaining meiotic arrest before ovulation. A zinc chelator [N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN)] caused premature germinal vesicle breakdown and associated spindle defects in denuded oocytes even in the presence of a phosphodiesterase 3A inhibitor (milrinone). TPEN also potently blocked cumulus expansion by blocking induction of expansion-related transcripts Has2, Ptx3, Ptgs2, and Tnfaip6 mRNA. Both meiotic arrest and cumulus expansion were rescued by exogenous zinc. Lack of cumulus expansion is due to an almost complete suppression of phospho-Sma- and Mad-related protein 2/3 signaling. Consistent with a decrease in phospho-Sma- and Mad-related protein 2/3 signaling, TPEN also decreased cumulus transcripts (Ar and Slc38a3) and caused a surprising increase in mural transcripts (Lhcgr and Cyp11a1) in cumulus cells. In vivo, feeding a zinc-deficient diet for 10 d completely blocked ovulation and compromised cumulus expansion. However, 42.5% of oocytes had prematurely resumed meiosis before human chorionic gonadotropin injection, underscoring the importance of zinc before ovulation. A more acute 3-d treatment with a zinc-deficient diet did not block ovulation but did increase the number of oocytes trapped in luteinizing follicles. Moreover, 23% of ovulated oocytes did not reach metaphase II due to severe spindle defects. Thus, acute zinc deficiency causes profound defects during the periovulatory period with consequences for oocyte maturation, cumulus expansion, and ovulation.

Subcellular localization of nardilysin during mouse oocyte maturation

We have previously shown that the peptidase, nardilysin, contains a bipartite nuclear localization signal that permits the enzyme to cycle between the nucleus and cytoplasm. In the present study, we report that nardilysin accumulates in the nucleus of an oocyte as a function of its maturation. Nardilysin is predominantly localized in the cytoplasm of an oocyte when initially placed into culture. The enzyme starts to accumulate in the nucleus within 30 min of in vitro culture. After 3 h, nardilysin is found as a spherical structure surrounded by condensed chromosomal DNA. After 18 h of in vitro culture, it co-localizes with β-tubulin at the spindle apparatus. Cilostamide, a phosphodiesterase 3A inhibitor that inhibits meiosis, blocks accumulation of nuclear nardilysin. This finding demonstrates that the nuclear entry of nardilysin is tightly controlled in the oocyte. Taken together, these experiments strongly suggest a role for nardilysin in meiosis through its dynamic translocation from cytosol to nucleus, and then to the spindle apparatus.