ABSTRACT
Based on the expanded theory of planned behavior, this study first explores the configuration relationship between founder management and innovation by using the fuzzy-set qualitative comparative analysis (fsQCA). Based on the theory of planned behavior, this study divides the behavior intention of founders into three categories: Attitude, subjective norm, and perceived behavior control. Using fsQCA, we found that there are two ways to achieve high innovation input of enterprises. In combination with the two ways, the factors such as male and highly educated founder, and large firm size can effectively increase the innovation input of firms, which is consistent with the three aspects of the behavioral intention of the theory of planned behavior, and it proves that the theory of planned behavior can effectively explain the configuration relation between the founder and firm innovation. In addition, this study finds that the innovation output is different from the innovation input, is dependent on the innovation ability of the firm itself, and is less influenced by the external environment.
ABSTRACT
Objectives: The use of assisted reproductive technology (ART) has increased rapidly in Taiwan. The purpose of this study is to discuss the risks of low birth weight, preterm birth, and birth defect for children conceived by assisted reproductive technology in Taiwan. Methods: Both National ART report database and National birth reports were obtained from the Health Promotion Administration in the Ministry of Health and Welfare in Taiwan. The cohort included live births (n = 1,405,625) and children conceived by ART (n = 50,988/172,818 cycles) from 2011 to 2017. The prevalence of low birth weight, preterm birth, and birth defect were compared between the ART and natural pregnancy groups. Results: Children conceived by ART displayed a higher rate of low birth weight as compared to those in the natural pregnancy group (p < 0.001), even when analyses were restricted to singleton births (p < 0.001). A higher rate of preterm birth (p < 0.001) was also observed in children conceived by ART even when analyses were restricted to singleton births (p < 0.05). A significant increased rate of birth defects was noted from children conceived by ART (p < 0.05). Conclusions: With the increasing need for and use of ART-conceptions, the likelihood of risks induced or related to Assistant Reproductive Technology (ART) has drawn considerable attention in recent years. Taiwan, as one of the leading countries with outstanding ART performances and modern medical care, the result of the current study suggests that further consideration and tighter regulations and policy are needed with regard to the use of ART.
ABSTRACT
Si-Wu Tang (SWT), a traditional Chinese formula, is commonly used for treating female diseases, such as relief of menstrual discomfort and climacteric syndrome. The aim of this study was to explore the synergistic effects between each herb in SWT on menstrual disorder patterns. Estradiol regulation and antioxidative effects were indicators that ameliorated menstrual disorder patterns and the total polyphenol and polysaccharide contents were quality markers. According to relationships of bioactivity and phytochemical contents, we discuss the effects of each herb in SWT. In a testosterone-treated MCF-7 cell model, Rehmannia glutinosa and catalpol significantly increased the estradiol content and aromatase upregulation in cell culture. We suggest that catalpol is an aromatase promoter in SWT, and R. glutinosa is a major actor. In terms of the antioxidant activity, pentagalloylglucose, gallic acid, and ferulic acid had stronger antioxidative effects than other compounds. We suggest that the antioxidative ability depends on polyphenols, and Paeonia lactiflora is a major contributor. Based on the prescribing principle of traditional Chinese medicine (TCM) theory, we suggest that R. glutinosa in SWT act as an aromatase promoter in the role of sovereign for ameliorating menstrual disorder patterns. As P. lactiflora has the strongest antioxidant effects and can prevent ROS damage ovarian; therefore, P. lactiflora could help R. glutinosa work as a minister for menstrual disorder patterns and R. glutinosa and P. lactiflora are a herbal pair in SWT.
ABSTRACT
High mobility group box 1 (HMGB1) is upregulated in nearly every tumor type. Importantly, clinical evidence also proposed that HMGB1 is particularly increased in metastatic prostate cancer patients. Besides, a growing number of studies highlighted that HMGB1 could be a successful therapeutic target for prostate cancer patients. Glycyrrhizin is a novel pharmacological inhibitor of HMGB1 that may repress prostate cancer metastasis. This research was aimed to investigate the effect of glycyrrhizin on inhibition of HMGB1-induced epithelial-to-mesenchymal transition (EMT), a key step of tumor metastasis, in prostate cancer cells. In this study, HMGB1 knock-downed DU145 prostate cancer cells were used. Silencing the HMGB1 gene expression triggered a change of cell morphology to a more epithelial-like shape, which was accompanied by a reduction of Cdc42/GSK-3ß/Snail and induction of E-cadherin levels estimated by immunoblotting. Furthermore, HMGB1 facilitated cell migration and invasion via downstream signaling, whereas HMGB1 targeting by 10 mM ethyl pyruvate effectively inhibited EMT characteristics. Interestingly, cell migration capacity induced by HMGB1 in DU145 cells was abolished in a dose-dependent effect of 25-200 µM glycyrrhizin treatment. In conclusion, glycyrrhizin successfully inhibited HMGB1-induced EMT phenomenon, which suggested that glycyrrhizin may serves as a therapeutic agent for metastatic prostate cancer.
Subject(s)
Epithelial-Mesenchymal Transition/drug effects , Glycyrrhizic Acid/pharmacology , HMGB1 Protein/metabolism , Prostatic Neoplasms/metabolism , Signal Transduction/drug effects , Animals , Cadherins/genetics , Cadherins/metabolism , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Glycogen Synthase Kinase 3 beta/genetics , Glycogen Synthase Kinase 3 beta/metabolism , HMGB1 Protein/genetics , Humans , Male , Prostate/drug effects , Prostate/metabolism , Prostatic Neoplasms/genetics , Prostatic Neoplasms/physiopathology , Snails/genetics , Snails/metabolismABSTRACT
Endometriosis is the major cause of female infertility and has been linked to the action of estrogen and estrogen receptor (ER). A new pool of ERß locates within mitochondria, which regulates the endometriotic cell withstanding external insults, but its effect remains controversial. We hypothesize that mitochondrial estrogen receptor ERß (mtERß) is a pivotal regulator in estradiol-mediated cell protection leading to the endometriotic progression. We observed elevated levels of ERß in the endometriotic tissues. A dramatic increase of ERß in mitochondria (mtERß) was found in the ectopic endometriotic tissues, or the estradiol-primed primary endometriotic cells. We analyzed the mtERß-specific overexpressing clone (mtsERß), which exhibited higher mitochondrial bioenergetics and lower reactive oxygen species (ROS) generation. The mtsERß-overexpressed endometriotic cells displayed an enhanced migration phenotype, whereas significantly attenuated migration by mitochondrial respiratory inhibitor (oligomycin) or ERß deficiency by shERß. Further investigations revealed that ERß directly modulated mitochondrial DNA (mtDNA) gene expression by interacting with mtDNA D-loop and polymerase γ. The mtsERß afforded a resistance to oxidative insult-induced apoptosis through the induction of the ROS scavenger enzyme Mn-superoxide dismutase and anti-apoptotic protein Bcl-2. Collectively, the demonstration of mtERß responses in restoration of mitochondrial bioenergetics and inhibition of mitochondria-dependent apoptotic events provides insight into the pathogenesis of endometriosis, suggesting ERß-selective estrogen receptor modulator may serve as novel therapeutics of endometriosis in the future.
Subject(s)
Apoptosis , Endometriosis/pathology , Estrogen Receptor beta/metabolism , Mitochondria/pathology , Oxidative Stress , Reactive Oxygen Species/metabolism , Endometriosis/metabolism , Energy Metabolism , Female , Humans , Mitochondria/metabolism , Mitochondrial Dynamics , Organelle Biogenesis , Protein TransportABSTRACT
Endometriosis is an estrogen-dependent inflammatory disease that affects up to 10% of women of reproductive age and accounts for up to 50% of female infertility cases. It has been highly associated with poorer outcomes of assisted reproductive technology (ART), including decreased oocyte retrieval, lower implantation, and pregnancy rates. A better understanding of the pathogenesis of endometriosis-associated infertility is crucial for improving infertility treatment outcomes. Current theories regarding how endometriosis reduces fertility include anatomical distortion, ovulatory dysfunction, and niche inflammation-associated peritoneal or implantation defects. This review will survey the latest evidence on the role of inflammatory niche in the peritoneal cavity, ovaries, and uterus of endometriosis patients. Nonhormone treatment strategies that target these inflammation processes are also included. Furthermore, mesenchymal stem cell-based therapies are highlighted for potential endometriosis treatment because of their immunomodulatory effects and tropism toward inflamed lesion foci. Potential applications of stem cell therapy in treatment of endometriosis-associated infertility in particular for safety and efficacy are discussed.
Subject(s)
Endometriosis/pathology , Infertility, Female/etiology , Endometriosis/complications , Endometriosis/drug therapy , Female , Humans , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Immunosuppressive Agents/therapeutic use , Infertility, Female/prevention & control , Mesenchymal Stem Cell Transplantation , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/metabolism , Ovary/metabolism , Ovary/pathology , Protein Kinase Inhibitors/therapeutic useABSTRACT
PURPOSE: To summarize available evidence from randomized-controlled trials which have evaluated triggering of final oocyte maturation with concomitant GnRH agonists and hCG in patients undergoing IVF, and to analyze whether dual triggering is as efficacious as hCG triggering in terms of oocyte and pregnancy outcomes. METHODS: A comprehensive literature search was performed to identify randomized-controlled trials comparing IVF outcomes between women receiving combined administration of hCG with GnRH agonists and those receiving hCG alone for triggering of final oocyte maturation. RESULTS: Four studies including 527 patients eligible for inclusion in meta-analysis were identified. No significant difference in the number of mature oocytes or fertilized oocytes retrieved was found between groups. Clinical pregnancy rate with dual triggering was significantly higher as compared with hCG-alone triggering (pooled OR = 0.48, 95% CI 0.31-0.77, P = 0.002), but there was no significant difference in the ongoing pregnancy rate between groups. CONCLUSION: Results of meta-analysis indicate comparable or significantly improved outcomes with the use of GnRH agonists plus hCG as compared with hCG alone for triggering of final oocyte maturation.
Subject(s)
Chorionic Gonadotropin/administration & dosage , Chorionic Gonadotropin/therapeutic use , Fertilization in Vitro/methods , Gonadotropin-Releasing Hormone/agonists , Hormone Antagonists/administration & dosage , Oogenesis/drug effects , Ovulation Induction/methods , Sperm Injections, Intracytoplasmic , Female , Humans , Oocytes/drug effects , Oocytes/growth & development , Pregnancy , Pregnancy Rate , Randomized Controlled Trials as TopicABSTRACT
The meiotic functions of Emi2, an inhibitor of the APC/C complex, have been best characterized in oocytes where it mediates metaphase II arrest as a component of the cytostatic factor. We generated knockout mice to determine the in vivo functions of Emi2-in particular, its functions in the testis, where Emi2 is expressed at high levels. Male and female Emi2 knockout mice are viable but sterile, indicating that Emi2 is essential for meiosis but dispensable for embryonic development and mitotic cell divisions. We found that, besides regulating cell-cycle arrest in mouse eggs, Emi2 is essential for meiosis I progression in spermatocytes. In the absence of Emi2, spermatocytes arrest in early diplotene of prophase I. This arrest is associated with decreased Cdk1 activity and was partially rescued by a knockin mouse model of elevated Cdk1 activity. Additionally, we detected expression of Emi2 in spermatids and sperm, suggesting potential post-meiotic functions for Emi2.
Subject(s)
F-Box Proteins/metabolism , Gene Expression Regulation/physiology , Meiotic Prophase I/physiology , Spermatids/metabolism , Spermatocytes/metabolism , Spermatogenesis/physiology , Animals , F-Box Proteins/genetics , Female , Male , Mice , Mice, KnockoutABSTRACT
OBJECTIVE: To review and evaluate the potential adverse effects of these oral contraceptives (OCP) to overweight women. CASE REPORT: A 19-year-old college student, with a body mass index (BMI) of 35.2 kg/m(2), who received 2 months of OCP containing cyproterone and ethinyl estradiol for polycystic ovary syndrome (PCOS)-related menstrual problems was complicated with a thromboembolism-related life-threatened disease. After intensive care, including the use of an extracorporeal membrane oxygenation system, thrombolytic treatment, anticoagulant, and inferior vena filter, she recovered well without significant sequelae. CONCLUSION: This case illustrates the risk of using OCPs, especially for those containing cyproterone and ethinyl estradiol components, as a treatment for menstrual problems in young women with PCOS and a high BMI.
Subject(s)
Contraceptives, Oral, Combined/adverse effects , Cyproterone/adverse effects , Ethinyl Estradiol/adverse effects , Menstruation Disturbances/drug therapy , Thromboembolism/chemically induced , Androgen Antagonists/adverse effects , Body Mass Index , Estrogens/adverse effects , Female , Humans , Menstruation Disturbances/etiology , Overweight/complications , Polycystic Ovary Syndrome/complications , Taiwan , Young AdultABSTRACT
Obesity results in increased secretion of cytokines from adipose tissue and is a risk factor for various cancers. Leptin is largely produced by adipose tissue and cancer cells. It induces cell proliferation and may serve to induce various cancers. OB3-leptin peptide (OB3) is a new class of functional leptin peptide. However, its mitogenic effect has not been determined. In the present study, because of a close link between leptin and the hypothalamic-pituitary-thyroid axis, OB3 was compared with leptin in different thyroid cancer cells for gene expression, proliferation and invasion. Neither agent stimulated cell proliferation. Leptin stimulated cell invasion, but reduced adhesion in anaplastic thyroid cancer cells. Activated ERK1/2 and STAT3 contributed to leptin-induced invasion. In contrast, OB3 did not affect expression of genes involved in proliferation and invasion. In vivo studies in the mouse showed that leptin, but not OB3, significantly increased circulating levels of thyrotropin (TSH), a growth factor for thyroid cancer. In summary, OB3 is a derivative of leptin that importantly lacks the mitogenic effects of leptin on thyroid cancer cells.
Subject(s)
Leptin/pharmacology , Peptide Fragments/pharmacology , Thyroid Neoplasms/metabolism , Thyroid Neoplasms/pathology , Animals , Carbohydrate Metabolism/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Disease Progression , Humans , Leptin/metabolism , Leptin/pharmacokinetics , Male , Mice , Mice, Inbred BALB C , Mice, Nude , Peptide Fragments/metabolism , Random Allocation , Signal Transduction , Thyroid Neoplasms/blood , Thyroid Neoplasms/genetics , Thyrotropin/bloodABSTRACT
In the ovary, the paracrine interactions between the oocyte and surrounded granulosa cells are critical for optimal oocyte quality and embryonic development. Mice lacking the androgen receptor (ARâ»/â») were noted to have reduced fertility with abnormal ovarian function that might involve the promotion of preantral follicle growth and prevention of follicular atresia. However, the detailed mechanism of how AR in granulosa cells exerts its effects on oocyte quality is poorly understood. Comparing in vitro maturation rate of oocytes, we found oocytes collected from ARâ»/â» mice have a significantly poor maturating rate with 60% reached metaphase II and 30% remained in germinal vesicle breakdown stage, whereas 95% of wild-type AR (ARâº/âº) oocytes had reached metaphase II. Interestingly, we found these ARâ»/â» female mice also had an increased frequency of morphological alterations in the mitochondria of granulosa cells with reduced ATP generation (0.18 ± 0.02 vs. 0.29 ± 0.02 µM/mg protein; p < 0.05) and aberrant mitochondrial biogenesis. Mechanism dissection found loss of AR led to a significant decrease in the expression of peroxisome proliferator-activated receptor γ (PPARγ) co-activator 1-ß (PGC1-ß) and its sequential downstream genes, nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM), in controlling mitochondrial biogenesis. These results indicate that AR may contribute to maintain oocyte quality and fertility via controlling the signals of PGC1-ß-mediated mitochondrial biogenesis in granulosa cells.
Subject(s)
Cell Differentiation , Granulosa Cells/pathology , Mitochondria/metabolism , Receptors, Androgen/deficiency , Animals , Cell Shape , Estradiol/blood , Female , Genotype , Granulosa Cells/metabolism , Granulosa Cells/ultrastructure , In Vitro Oocyte Maturation Techniques , Membrane Potential, Mitochondrial , Mice, Knockout , Mitochondria/ultrastructure , Oocytes/metabolism , Organelle Biogenesis , Receptors, Androgen/metabolism , Reproducibility of ResultsABSTRACT
OBJECTIVE: This study was conducted to explore the association between sexual orientations and polycystic ovary syndrome (PCOS)-related parameters. MATERIALS AND METHODS: A cross-sectional study with participants recruited from the regular outpatient clinic at the Department of Obstetrics and Gynecology at Taipei Medical University Hospital, Taipei, Taiwan between July 2012 and December 2013 was carried out. A total of 97 women met the criterion of having been diagnosed with PCOS. Among these 97 women, 89 were heterosexuals and eight were self-identified as lesbians. At the same time, 78 women without PCOS were enrolled to serve as the control group. Participants were given a standard questionnaire and had blood withdrawn for biochemical analysis of androgen parameters--including total testosterone, androstenedione, sex hormone binding globulin, free androgen index, 17ß-estradiol (E2), luteinizing hormone, and follicular-stimulating hormone. The biochemical data were measured to compare the PCOS clinical parameters present in people of different sexual orientations (lesbians and heterosexuals). RESULTS: The women with PCOS, regardless of sexual orientation, had higher percentages and serum levels of hyperandrogenism-related clinical parameters than the women without PCOS [acne (87.5% and 60.7% vs. 23.1%), p < 0.001]; hirsutism (62.5% and 57.3% vs. 15.4%, p ≤ 0.001)]; and biochemical parameters (total T, p < 0.05 or p < 0.001, and luteinizing hormone/follicular-stimulating hormone ratio, p ≤ 0.001]. The sexual orientation of women with PCOS affected their body mass index (BMI), because lesbians with PCOS possessed higher BMI than heterosexual women with PCOS (26.5 ± 1.9 vs. 22.5 ± 0.55; p < 0.05). However, hyperandrogenism-related clinical and biochemical parameters were not significantly different statistically between women with PCOS but of different sexual orientations. CONCLUSION: Our preliminary data showed that sexual orientation influenced the BMI of women with PCOS, but did not affect hyperandrogenism-related clinical or biochemical characteristics. This observation requires further confirmation.
Subject(s)
Heterosexuality/statistics & numerical data , Homosexuality, Female/statistics & numerical data , Polycystic Ovary Syndrome/psychology , Adult , Biomarkers/blood , Case-Control Studies , Cross-Sectional Studies , Female , Humans , Hyperandrogenism/blood , Hyperandrogenism/diagnosis , Hyperandrogenism/etiology , Hyperandrogenism/psychology , Polycystic Ovary Syndrome/blood , Polycystic Ovary Syndrome/complications , Surveys and Questionnaires , TaiwanABSTRACT
Vertebrate eggs arrest at second meiotic metaphase. The fertilizing sperm causes meiotic exit through Ca(2+)-mediated activation of the anaphase-promoting complex/cyclosome (APC/C). Although the loss in activity of the M-phase kinase CDK1 is known to be an essential downstream event of this process, the contribution of phosphatases to arrest and meiotic resumption is less apparent, especially in mammals. Therefore, we explored the role of protein phosphatase 2A (PP2A) in mouse eggs using pharmacological inhibition and activation as well as a functionally dominant-negative catalytic PP2A subunit (dn-PP2Ac-L199P) coupled with live cell imaging. We observed that PP2A inhibition using okadaic acid induced events normally observed at fertilization: degradation of the APC/C substrates cyclin B1 and securin resulting from loss of the APC/C inhibitor Emi2. Although sister chromatids separated, chromatin remained condensed, and polar body extrusion was blocked as a result of a rapid spindle disruption, which could be ameliorated by non-degradable cyclin B1, suggesting that spindle integrity was affected by CDK1 loss. Similar cell cycle effects to okadaic acid were also observed using dominant-negative PP2Ac. Preincubation of eggs with the PP2A activator FTY720 could block many of the actions of okadaic acid, including Emi2, cyclin B1, and securin degradation and sister chromatid separation. Therefore, in conclusion, we used okadaic acid, dn-PP2Ac-L199P, and FTY720 on mouse eggs to demonstrate that PP2A is needed to for both continued metaphase arrest and successful exit from meiosis.
Subject(s)
Gene Expression Regulation, Enzymologic , Metaphase/drug effects , Okadaic Acid/pharmacology , Oocytes/drug effects , Propylene Glycols/pharmacology , Protein Phosphatase 2/genetics , Protein Phosphatase 2/metabolism , Sphingosine/analogs & derivatives , Animals , Chromatids/chemistry , Cyclin B1/metabolism , Female , Fingolimod Hydrochloride , Genes, Dominant , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Oocytes/metabolism , Sphingosine/pharmacology , Spindle ApparatusABSTRACT
Previous studies have established that when maturing mouse oocytes are continuously incubated with the Aurora inhibitor ZM447439, meiotic maturation is blocked. In this study, we observe that by altering the time of addition of the inhibitor, oocyte maturation can actually be accelerated by 1 h as measured by the timing of polar body extrusion. ZM447439 also had the ability to overcome a spindle assembly checkpoint (SAC) arrest caused by nocodazole and so rescue polar body extrusion. Consistent with the ability of the SAC to inhibit cyclin B1 degradation by blocking activation of the anaphase-promoting complex, we could also observe a rescue in cyclin B1 degradation when ZM447439 was added to nocodazole-treated oocytes. The acceleration of the first meiotic division by ZM447439, which has not been achieved previously, and its effects on the SAC are all consistent with the proposed mitotic role of Aurora B in activating the SAC. We hypothesize that Aurora kinase activity controls the SAC in meiosis I, despite differences to the mitotic cell cycle division in spindle architecture brought about by the meiotic mono-orientation of sister kinetochores.
Subject(s)
Benzamides/pharmacology , Meiosis/physiology , Oocytes/physiology , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/physiology , Quinazolines/pharmacology , Spindle Apparatus/physiology , Anaphase-Promoting Complex-Cyclosome , Animals , Aurora Kinase B , Aurora Kinases , Crosses, Genetic , Cyclin B1/physiology , Female , Kinetochores/physiology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Microscopy, Confocal , Microscopy, Fluorescence , Ploidies , Protein Serine-Threonine Kinases/antagonists & inhibitors , Time-Lapse Imaging , Ubiquitin-Protein Ligase Complexes/physiologyABSTRACT
Mature mammalian eggs are ovulated arrested at meiotic metaphase II. Sperm break this arrest by an oscillatory Ca(2+) signal that is necessary and sufficient for the two immediate events of egg activation: cell cycle resumption and cortical granule release. Previous work has suggested that cell cycle resumption, but not cortical granule release, is mediated by calmodulin-dependent protein kinase II (CamKII). Here we find that mouse eggs contain detectable levels of only one CamKII isoform, gamma 3. Antisense morpholino knockdown of CamKIIgamma3 during oocyte maturation produces metaphase II eggs that are insensitive to parthenogenetic activation by Ca(2+) stimulation and insemination. The effect is specific to this morpholino, as a 5-base-mismatch morpholino is without effect, and is rescued by CamKIIgamma3 or constitutively active CamKII cRNAs. Although CamKII-morpholino-treated eggs fail to exit metaphase II arrest, cortical granule exocytosis is not blocked. Therefore, CamKIIgamma3 plays a necessary and sufficient role in transducing the oscillatory Ca(2+) signal into cell cycle resumption, but not into cortical granule release.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinase Type 2/physiology , Isoenzymes/physiology , Metaphase/physiology , Oocytes , Animals , Antisense Elements (Genetics) , Calcium Signaling/genetics , Cell Cycle/physiology , Down-Regulation , Exocytosis/physiology , Female , Gene Expression Regulation, Enzymologic , In Vitro Techniques , Mice , Oocytes/cytology , Oocytes/physiology , Parthenogenesis/physiology , RNA, ComplementaryABSTRACT
The first female meiotic division (meiosis I, MI) is uniquely prone to chromosome segregation errors through non-disjunction, resulting in trisomies and early pregnancy loss. Here, we show a fundamental difference in the control of mammalian meiosis that may underlie such susceptibility. It involves a reversal in the well-established timing of activation of the anaphase-promoting complex (APC) by its co-activators cdc20 and cdh1. APC(cdh1) was active first, during prometaphase I, and was needed in order to allow homologue congression, as loss of cdh1 speeded up MI, leading to premature chromosome segregation and a non-disjunction phenotype. APC(cdh1) targeted cdc20 for degradation, but did not target securin or cyclin B1. These were degraded later in MI through APC(cdc20), making cdc20 re-synthesis essential for successful meiotic progression. The switch from APC(cdh1) to APC(cdc20) activity was controlled by increasing CDK1 and cdh1 loss. These findings demonstrate a fundamentally different mechanism of control for the first meiotic division in mammalian oocytes that is not observed in meioses of other species.
Subject(s)
Oocytes/metabolism , Prometaphase/physiology , Ubiquitin-Protein Ligase Complexes/metabolism , Anaphase-Promoting Complex-Cyclosome , Animals , Blotting, Western , Carrier Proteins/genetics , Carrier Proteins/metabolism , Cdc20 Proteins , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cyclin B/genetics , Cyclin B/metabolism , Cyclin B1 , Female , Meiosis/genetics , Meiosis/physiology , Mice , Microscopy, Fluorescence , Prometaphase/genetics , Securin , Time Factors , Ubiquitin-Protein Ligase Complexes/geneticsABSTRACT
Cdc20 and cdh1 are coactivators of the anaphase-promoting complex (APC). APC(cdc20) is necessary for the metaphase-anaphase transition and, at the end of mitosis, vertebrate cdc20 itself becomes a target for degradation through KEN-box-dependent APC(cdh1) activity. By studying the degradation of fluorescent protein chimaeras in mammalian oocytes and early embryos, we found that cdc20 was degraded through two independent degradation signals (degrons), the KEN box and a newly described CRY box. In both oocytes and G1-stage embryos, the rate of degradation through the CRY box was greater than through the KEN box, although both were mediated by APC(cdh1). Thus, mammalian oocytes and embryos have the capacity to recognize two degrons in cdc20.
Subject(s)
Cell Cycle Proteins/chemistry , Cell Cycle Proteins/metabolism , Ubiquitin-Protein Ligase Complexes/metabolism , Anaphase-Promoting Complex-Cyclosome , Animals , Cdc20 Proteins , Cell Cycle Proteins/genetics , Embryo, Mammalian/metabolism , Female , G1 Phase , Green Fluorescent Proteins/chemistry , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Meiotic Prophase I , Mice , Oocytes/metabolism , Protein Denaturation , Protein Sorting Signals , Protein Structure, Tertiary , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolismABSTRACT
Fully grown mammalian oocytes maintain a prophase I germinal-vesicle stage arrest in the ovary for extended periods before a luteinizing hormone surge induces entry into the first meiotic division. Cdh1 is an activator of the anaphase-promoting complex (APC) and APCcdh1 is normally restricted to late M to early G1 phases of the cell cycle. Here, we find that APCcdh1 is active in mouse oocytes and is necessary to maintain prophase arrest.
Subject(s)
Meiotic Prophase I/physiology , Oocytes/cytology , Oocytes/metabolism , Ubiquitin-Protein Ligase Complexes/metabolism , Anaphase-Promoting Complex-Cyclosome , Animals , Mice , RNA, Complementary/genetics , Time FactorsABSTRACT
Metaphase II-arrested mouse eggs are stimulated to complete meiosis by sperm-induced Ca2+ spiking. The Ca2+ signal causes activation of the E3 ligase anaphase-promoting complex/cyclosome (APC), leading to the destruction of key proteins necessary for meiotic exit. We show, using western blots of mouse eggs, the presence of both APC activators cdc20 and cdh1, which target D-box and D-box/KEN-box substrates, respectively, for proteolysis. We decided to examine the temporal activation of APCcdc20 and APCcdh1 by coupling APC substrates to GFP and examining their destruction in real-time following release from second meiotic division arrest. D-box substrates were degraded quickly after the initiation of sperm-induced Ca2+ spiking, such that their degradation was complete by the time of second polar body extrusion. By contrast, KEN-box-containing substrates were degraded when CDK1 activity was low, during the period between polar body extrusion and pronucleus formation. This observation of apparent APCcdh1 activity in meiosis II based on destruction of exogenous GFP-coupled substrates was then confirmed by observing destruction of endogenous APCcdh1 substrates. These data are consistent with a model of initial APCcdc20 activation on sperm-induced activation, followed by APCcdh1 activation after second polar body extrusion. Interestingly, therefore, we propose that mammalian eggs undergo meiosis II with both APCcdc20 and APCcdh1, whereas eggs of other species so far described have APCcdc20 activity only.