Journal articles on the topic 'Meiotic inhibition'
To see the other types of publications on this topic, follow the link: Meiotic inhibition.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Meiotic inhibition.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Dudley, Keith. "Meiotic Inhibition - Molecular Control of Meiosis." FEBS Letters 253, no. 1-2 (August 14, 1989): 293–94. http://dx.doi.org/10.1016/0014-5793(89)80984-6.
Full text
2
Wang, Xia, Jason E. Swain, Mathieu Bollen, Xiao-Tie Liu, Dana A. Ohl, and Gary D. Smith. "Endogenous regulators of protein phosphatase-1 during mouse oocyte development and meiosis." Reproduction 128, no. 5 (November 2004): 493–502. http://dx.doi.org/10.1530/rep.1.00173.
Full textAbstract:
Reversible phosphorylation, involving protein kinases and phosphatases (PP), is important in regulating oocyte meiosis. Okadaic acid (OA) inhibition of PP1 and/or PP2A stimulates oocyte germinal vesicle breakdown (GVB). In oocytes, PP1 is localized in the cytoplasm and nucleus, yet endogenous regulation of oocyte PP1 has not been investigated. The objectives of the study were to identify intra-oocyte mechanisms regulating PP1 during acquisition of OA-sensitive meiotic competence and meiotic resumption. Immunohistochemical studies revealed that GVB-incompetent oocytes contained equivalent cytoplasmic and nuclear PP1. Upon development of OA-sensitive meiotic competence, PP1 displayed differential intracellular localization with significantly greater nuclear staining with distinct nucleolar rimming compared with cytoplasmic staining. Germinal vesicle-intact oocytes contained neither nuclear inhibitor of PP1, nor PP1 cytoplasmic inhibitor-1 transcripts or proteins. Reverse transcription-PCR with PP1 cytoplasmic inhibitor-2 (I2) primers and oocyte RNA amplified a predicted 330-bp product with the identical sequence to mouse liver I2. Oocytes contained a heat-stable PP1 inhibitor with biochemical properties of I2. Phosphorylation of PP1 at Thr320 by cyclin dependent kinase-1 (CDK1) causes PP1 inactivation. Germinal vesicle-intact oocytes did not contain phospho-Thr320-PP1. Upon GVB, PP1 became phosphorylated at Thr320 and this phosphorylation did not occur if GVB was blocked with the CDK1 inhibitor, roscovitine (ROSC). Inhibition of oocyte GVB with ROSC was reversible and coincided with PP1 phosphorylation at Thr320. Increased oocyte staining of nuclear PP1 compared with cytoplasmic staining at a chronological stage when oocytes gain meiotic competence, and phosphorylation and inhibition of PP1 by CDK1 at or around GVB appear to be important mechanisms in regulating oocyte PP1 activity and meiosis. In addition, these studies provide further support for PP1 being the OA-sensitive PP important in the regulation of the acquisition of meiotic competence, nuclear events during meiotic arrest, and GVB.
3
Chen, Hanchen, Chengpeng He, Chongyang Wang, Xuanpeng Wang, Fengyin Ruan, Junjie Yan, Ping Yin, Yingxiang Wang, and Shunping Yan. "RAD51 supports DMC1 by inhibiting the SMC5/6 complex during meiosis." Plant Cell 33, no. 8 (May 16, 2021): 2869–82. http://dx.doi.org/10.1093/plcell/koab136.
Full textAbstract:
Abstract Meiosis is a fundamental process for sexual reproduction in most eukaryotes and the evolutionarily conserved recombinases RADiation sensitive51 (RAD51) and Disrupted Meiotic cDNA1 (DMC1) are essential for meiosis and thus fertility. The mitotic function of RAD51 is clear, but the meiotic function of RAD51 remains largely unknown. Here we show that RAD51 functions as an interacting protein to restrain the Structural Maintenance of Chromosomes5/6 (SMC5/6) complex from inhibiting DMC1. We unexpectedly found that loss of the SMC5/6 partially suppresses the rad51 knockout mutant in terms of sterility, pollen inviability, and meiotic chromosome fragmentation in a DMC1-dependent manner in Arabidopsis thaliana. Biochemical and cytological studies revealed that the DMC1 localization in meiotic chromosomes is inhibited by the SMC5/6 complex, which is attenuated by RAD51 through physical interactions. This study not only identified the long-sought-after function of RAD51 in meiosis but also discovered the inhibition of SMC5/6 on DMC1 as a control mechanism during meiotic recombination.
4
Hanna, Carol, Suzanne Menges, Duane Kraemer, and Charles R. Long. "Synchronisation of canine germinal vesicle stage oocytes prior to in vitro maturation alters the kinetics of nuclear progression during subsequent resumption of meiosis." Reproduction, Fertility and Development 20, no. 5 (2008): 606. http://dx.doi.org/10.1071/rd07227.
Full textAbstract:
Inhibition of meiosis before in vitro maturation (IVM) can improve meiotic competence in immature mammalian oocytes. Therefore, meiosis-inhibiting agents were evaluated singularly for the ability to arrest and synchronise germinal vesicle (GV) stage canine oocytes, and the most effective treatments were combined to improve meiotic resumption rates. Oocytes cultured in 2 ng mL–1 oestradiol (E2), 10 IU mL–1 eCG, or both (EG) for 72 h resulted in significantly fewer oocytes resuming meiosis in EG than the control, E2, or with eCG. Oocytes cultured in 50 or 100 μmol L–1 of butyrolactone 1 or roscovitine (ROS) for up to 48 h did not resume meiosis nor increase subsequent meiotic resumption rates following IVM. A combination of 50 μmol L–1 ROS and EG treatment for 48 h significantly increased the proportion of canine oocytes in meiotic arrest. More importantly, following 48 h of IVM, ROS+EG-treated oocytes demonstrated a dramatic increase in the ability to resume meiosis compared with the non-treated controls (51.3 ± 8.2% and 10.8 ± 4.5%, respectively; P < 0.05). These data indicate that chemical and biological meiotic inhibitors are effective at inducing GV arrest in canine oocytes. Furthermore, these inhibitors are reversible and beneficial to subsequent meiotic resumption in vitro.
5
Marangos, Petros, Emmy W. Verschuren, Ruby Chen, Peter K. Jackson, and John Carroll. "Prophase I arrest and progression to metaphase I in mouse oocytes are controlled by Emi1-dependent regulation of APCCdh1." Journal of Cell Biology 176, no. 1 (December 26, 2006): 65–75. http://dx.doi.org/10.1083/jcb.200607070.
Full textAbstract:
Mammalian oocytes are arrested in prophase of the first meiotic division. Progression into the first meiotic division is driven by an increase in the activity of maturation-promoting factor (MPF). In mouse oocytes, we find that early mitotic inhibitor 1 (Emi1), an inhibitor of the anaphase-promoting complex (APC) that is responsible for cyclin B destruction and inactivation of MPF, is present at prophase I and undergoes Skp1–Cul1–F-box/βTrCP-mediated destruction immediately after germinal vesicle breakdown (GVBD). Exogenous Emi1 or the inhibition of Emi1 destruction in prophase-arrested oocytes leads to a stabilization of cyclin B1–GFP that is sufficient to trigger GVBD. In contrast, the depletion of Emi1 using morpholino oligonucleotides increases cyclin B1–GFP destruction, resulting in an attenuation of MPF activation and a delay of entry into the first meiotic division. Finally, we show that Emi1-dependent effects on meiosis I require the presence of Cdh1. These observations reveal a novel mechanism for the control of entry into the first meiotic division: an Emi1-dependent inhibition of APCCdh1.
6
Cairo, Albert, Anna Vargova, Neha Shukla, Claudio Capitao, Pavlina Mikulkova, Sona Valuchova, Jana Pecinkova, Petra Bulankova, and Karel Riha. "Meiotic exit in Arabidopsis is driven by P-body–mediated inhibition of translation." Science 377, no. 6606 (August 5, 2022): 629–34. http://dx.doi.org/10.1126/science.abo0904.
Full textAbstract:
Meiosis, at the transition between diploid and haploid life cycle phases, is accompanied by reprograming of cell division machinery and followed by a transition back to mitosis. We show that, in Arabidopsis , this transition is driven by inhibition of translation, achieved by a mechanism that involves processing bodies (P-bodies). During the second meiotic division, the meiosis-specific protein THREE-DIVISION MUTANT 1 (TDM1) is incorporated into P-bodies through interaction with SUPPRESSOR WITH MORPHOGENETIC EFFECTS ON GENITALIA 7 (SMG7). TDM1 attracts eIF4F, the main translation initiation complex, temporarily sequestering it in P-bodies and inhibiting translation. The failure of tdm1 mutants to terminate meiosis can be overcome by chemical inhibition of translation. We propose that TDM1-containing P-bodies down-regulate expression of meiotic transcripts to facilitate transition of cell fates to postmeiotic gametophyte differentiation.
7
Cao, Zubing, Tengteng Xu, Xu Tong, Dandan Zhang, Chengxue Liu, Yiqing Wang, Di Gao, et al. "HASPIN kinase mediates histone deacetylation to regulate oocyte meiotic maturation in pigs." Reproduction 157, no. 6 (June 2019): 501–10. http://dx.doi.org/10.1530/rep-18-0447.
Full textAbstract:
HASPIN kinase-catalyzed phosphorylation of histone H3 on threonine 3 (H3T3p) directs the activity and localization of chromosomal passenger complex (CPC) and spindle assembly checkpoint (SAC) to regulate chromosome condensation and segregation in both mitosis and meiosis. However, the function of HASPIN kinase in the meiotic maturation of porcine oocytes is not yet known. Here, we found that HASPIN mRNA is constantly expressed in porcine oocyte maturation and subsequent early embryo development. H3T3p is highly enriched on chromosomes at germinal vesicle breakdown (GVBD) stage and thereafter maintains a low level in progression through metaphase I (MI) to metaphase II (MII). Correspondingly, H3T3p was completely abolished in oocytes treated with an inhibitor of HASPIN kinase. Functionally, inhibition of HASPIN activity led to a significant reduction in the rate of oocyte meiotic maturation and the limited cumulus expansion. Additionally, HASPIN inhibition caused both spindle disorganization and chromosome misalignment in oocytes at MI and MII stage. Importantly, HASPIN inhibition severely prevented deacetylation of several highly conserved lysine (K) residues of histone H3 and H4 including H3K9, H3K14, H4K5, H4K8, H4K12 and H4K16 on the metaphase chromosomes during oocyte meiotic maturation. Taken together, these results demonstrate that HASPIN kinase regulates porcine oocyte meiotic maturation via modulating histone deacetylation.
8
Honigberg, Saul M., and Rita H. Lee. "Snf1 Kinase Connects Nutritional Pathways Controlling Meiosis in Saccharomyces cerevisiae." Molecular and Cellular Biology 18, no. 8 (August 1, 1998): 4548–55. http://dx.doi.org/10.1128/mcb.18.8.4548.
Full textAbstract:
ABSTRACT Glucose inhibits meiosis in Saccharomyces cerevisiae at three different steps (IME1 transcription, IME2transcription, and entry into late stages of meiosis). Because many of the regulatory effects of glucose in yeast are mediated through the inhibition of Snf1 kinase, a component of the glucose repression pathway, we determined the role of SNF1 in regulating meiosis. Deleting SNF1 repressed meiosis at the same three steps that were inhibited by glucose, suggesting that glucose blocks meiosis by inhibiting Snf1. For example, the snf1Δ mutant completely failed to induce IME1 transcripts in sporulation medium. Furthermore, even when this block was bypassed by expression ofIME1 from a multicopy plasmid, IME2transcription and meiotic initiation occurred at only 10 to 20% of the levels seen in wild-type cells. The addition of glucose did not further inhibit IME2 transcription, suggesting that Snf1 is the primary mediator of glucose controls on IME2 expression. Finally, in snf1Δ cells in which both blocks on meiotic initiation were bypassed, early stages of meiosis (DNA replication and commitment to recombination) occurred, but later stages (chromosome segregation and spore formation) did not, suggesting that Snf1 controls later stages of meiosis independently from the two controls on meiotic initiation. Because Snf1 is known to activate the expression of genes required for acetate metabolism, it may also serve to connect glucose and acetate controls on meiotic differentiation.
9
Zhang, Jin, Lihua Ren, Yang Zou, Lianshuang Zhang, Jialiu Wei, Yanbo Li, Ji Wang, Zhiwei Sun, and Xianqing Zhou. "Silica nanoparticles induce start inhibition of meiosis and cell cycle arrest via down-regulating meiotic relevant factors." Toxicology Research 5, no. 5 (2016): 1453–64. http://dx.doi.org/10.1039/c6tx00236f.
Full textAbstract:
Silica nanoparticles induced cell cycle arrest and proliferation inhibition by down-regulating the expressions of meiotic regulatory factors through causing DNA damages resulting from oxidative stress, leading to the inhibition of the start and process of meiosis.
10
Varadarajan, Ramya, Joseph Ayeni, Zhigang Jin, Ellen Homola, and Shelagh D. Campbell. "Myt1 inhibition of Cyclin A/Cdk1 is essential for fusome integrity and premeiotic centriole engagement in Drosophila spermatocytes." Molecular Biology of the Cell 27, no. 13 (July 2016): 2051–63. http://dx.doi.org/10.1091/mbc.e16-02-0104.
Full textAbstract:
Regulation of cell cycle arrest in premeiotic G2 phase coordinates germ cell maturation and meiotic cell division with hormonal and developmental signals by mechanisms that control Cyclin B synthesis and inhibitory phosphorylation of the M-phase kinase, Cdk1. In this study, we investigated how inhibitory phosphorylation of Cdk1 by Myt1 kinase regulates premeiotic G2 phase of Drosophila male meiosis. Immature spermatocytes lacking Myt1 activity exhibit two distinct defects: disrupted intercellular bridges (fusomes) and premature centriole disengagement. As a result, the myt1 mutant spermatocytes enter meiosis with multipolar spindles. These myt1 defects can be suppressed by depletion of Cyclin A activity or ectopic expression of Wee1 (a partially redundant Cdk1 inhibitory kinase) and phenocopied by expression of a Cdk1F mutant defective for inhibitory phosphorylation. We therefore conclude that Myt1 inhibition of Cyclin A/Cdk1 is essential for normal fusome behavior and centriole engagement during premeiotic G2 arrest of Drosophila male meiosis. The novel meiotic functions we discovered for Myt1 kinase are spatially and temporally distinct from previously described functions of Myt1 as an inhibitor of Cyclin B/Cdk1 to regulate G2/MI timing.
11
McNally, Karen, Anjon Audhya, Karen Oegema, and Francis J. McNally. "Katanin controls mitotic and meiotic spindle length." Journal of Cell Biology 175, no. 6 (December 18, 2006): 881–91. http://dx.doi.org/10.1083/jcb.200608117.
Full textAbstract:
Accurate control of spindle length is a conserved feature of eukaryotic cell division. Lengthening of mitotic spindles contributes to chromosome segregation and cytokinesis during mitosis in animals and fungi. In contrast, spindle shortening may contribute to conservation of egg cytoplasm during female meiosis. Katanin is a microtubule-severing enzyme that is concentrated at mitotic and meiotic spindle poles in animals. We show that inhibition of katanin slows the rate of spindle shortening in nocodazole-treated mammalian fibroblasts and in untreated Caenorhabditis elegans meiotic embryos. Wild-type C. elegans meiotic spindle shortening proceeds through an early katanin-independent phase marked by increasing microtubule density and a second, katanin-dependent phase that occurs after microtubule density stops increasing. In addition, double-mutant analysis indicated that γ-tubulin–dependent nucleation and microtubule severing may provide redundant mechanisms for increasing microtubule number during the early stages of meiotic spindle assembly.
12
Bellutti, Laura, Emilie Abby, Sophie Tourpin, Sébastien Messiaen, Delphine Moison, Emilie Trautmann, Marie-Justine Guerquin, Virginie Rouiller-Fabre, René Habert, and Gabriel Livera. "Divergent Roles of CYP26B1 and Endogenous Retinoic Acid in Mouse Fetal Gonads." Biomolecules 9, no. 10 (September 26, 2019): 536. http://dx.doi.org/10.3390/biom9100536.
Full textAbstract:
In female mammals, germ cells enter meiosis in the fetal ovaries, while in males, meiosis is prevented until postnatal development. Retinoic acid (RA) is considered the main inducer of meiotic entry, as it stimulates Stra8 which is required for the mitotic/meiotic switch. In fetal testes, the RA-degrading enzyme CYP26B1 prevents meiosis initiation. However, the role of endogenous RA in female meiosis entry has never been demonstrated in vivo. In this study, we demonstrate that some effects of RA in mouse fetal gonads are not recapitulated by the invalidation or up-regulation of CYP26B1. In organ culture of fetal testes, RA stimulates testosterone production and inhibits Sertoli cell proliferation. In the ovaries, short-term inhibition of RA-signaling does not decrease Stra8 expression. We develop a gain-of-function model to express CYP26A1 or CYP26B1. Only CYP26B1 fully prevents STRA8 induction in female germ cells, confirming its role as part of the meiotic prevention machinery. CYP26A1, a very potent RA degrading enzyme, does not impair the formation of STRA8-positive cells, but decreases Stra8 transcription. Collectively, our data reveal that CYP26B1 has other activities apart from metabolizing RA in fetal gonads and suggest a role of endogenous RA in amplifying Stra8, rather than being the initial inducer of Stra8. These findings should reactivate the quest to identify meiotic preventing or inducing substances.
13
Chmelíková, Eva, Michal Ješeta, Markéta Sedmíková, Jaroslav Petr, Lenka Tůmová, Tomáš Kott, Petra Lipovová, and František Jílek. "Nitric oxide synthase isoforms and the effect of their inhibition on meiotic maturation of porcine oocytes." Zygote 18, no. 3 (January 29, 2010): 235–44. http://dx.doi.org/10.1017/s0967199409990268.
Full textAbstract:
SummaryIn this paper we assessed: (i) the change in nitric oxide synthase (NOS) isoforms' expression and intracellular localization and in NOS mRNA in porcine oocytes during meiotic maturation; (ii) the effect of NOS inhibition by Nω-nitro-l-arginine methyl ester (l-NAME) and aminoguanidine (AG) on meiotic maturation of cumulus–oocyte complexes (COC) as well as denuded oocytes (DO); and (iii) nitric oxide (NO) formation in COC. All three NOS isoforms (eNOS, iNOS and nNOS) and NOS mRNA (eNOS mRNA, iNOS mRNA and nNOS mRNA) were found in both porcine oocytes and their cumulus cells except for nNOS mRNA, which was not detected in the cumulus cells. NOS isoforms differed in their intracellular localization in the oocyte: while iNOS protein was dispersed in the oocyte cytoplasm, nNOS was localized in the oocyte cytoplasm and in germinal vesicles (GV) and eNOS was present in dots in the cytoplasm, GV and was associated with meiotic spindles. l-NAME inhibitor significantly suppressed metaphase (M)I to MII transition (5.0 mM experimental group: 34.9% MI, control group: 9.5% MI) and at the highest concentration (10.0 mM) also affected GV breakdown (GVBD); in contrast also AG inhibited primarily GVBD. The majority of the oocytes (10.0 mM experimental group: 60.8%, control group: 1.2%) was not able to resume meiosis. AG significantly inhibited GVBD in DO, but l-NAME had no significant effect on the GVBD of these cells. During meiotic maturation, NO is formed in COC and the NO formed by cumulus cells is necessary for the process of GVBD.
14
Wang, Yakun, Nana Kong, Na Li, Xiaoqiong Hao, Kaiwen Wei, Xi Xiang, Guoliang Xia, and Meijia Zhang. "Epidermal Growth Factor Receptor Signaling-Dependent Calcium Elevation in Cumulus Cells Is Required for NPR2 Inhibition and Meiotic Resumption in Mouse Oocytes." Endocrinology 154, no. 9 (June 20, 2013): 3401–9. http://dx.doi.org/10.1210/en.2013-1133.
Full textAbstract:
In preovulatory ovarian follicles, the oocyte is maintained in meiotic prophase arrest by natriuretic peptide precursor C (NPPC) and its receptor natriuretic peptide receptor 2 (NPR2). LH treatment results in the decrease of NPR2 guanylyl cyclase activity that promotes resumption of meiosis. We investigated the regulatory mechanism of LH-activated epidermal growth factor (EGF) receptor signaling on NPR2 function. Cumulus cell-oocyte complex is cultured in the medium with 30 nM NPPC to prevent oocyte spontaneous maturation. In this system, EGF could stimulate oocyte meiotic resumption after 4 hours of incubation. Further study showed that EGF elevated intracellular calcium concentrations of cumulus cells and decreased cGMP levels in cumulus cells and oocytes, and calcium-elevating reagents ionomycin and sphingosine-1-phosphate mimicked the effects of EGF on oocyte maturation and cGMP levels. EGF-mediated cGMP levels and meiotic resumption could be reversed by EGF receptor inhibitor AG1478 and the calcium chelator bis-(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid, tetra(acetoxymethyl)-ester. EGF also decreased the expression of Npr2 mRNA in cumulus cells, which may not be involved in meiotic resumption, because the block of NPR2 protein de novo synthesis by cycloheximide had no effect on NPPC and EGF-mediated oocyte maturation. However, EGF had no effect on oocyte maturation when meiotic arrest was maintained in the present of cGMP analog 8-bromoadenosine-cGMP. These results suggest that EGF receptor signaling induces meiotic resumption by elevating calcium concentrations of cumulus cells to decrease NPR2 guanylyl cyclase activity.
15
Ohsumi, K., W. Sawada, and T. Kishimoto. "Meiosis-specific cell cycle regulation in maturing Xenopus oocytes." Journal of Cell Science 107, no. 11 (November 1, 1994): 3005–13. http://dx.doi.org/10.1242/jcs.107.11.3005.
Full textAbstract:
Meiotic cell cycles differ from mitotic cell cycles in that the former lack S-phase in the interphase between meiosis I and meiosis II. To obtain clues for mechanisms involved in the cell cycle regulation unique to meiosis, we have examined changes in chromosomal morphology and H1 kinase activity during a meiotic period from metaphase I (MI) to metaphase II (MII) in Xenopus oocytes. Using populations of oocytes that underwent germinal vesicle breakdown (GVBD) within a 10 minute interval, we found that the kinase activity declined gradually during the 60 minute period after GVBD and then increased steadily during the following 80 minute interval, showing remarkable differences from the rapid drop and biphasic increase of the kinase activity in intermitotic periods (Solomon et al. (1990) Cell 63, 1013–1024; Dasso and Newport (1990) Cell 61, 811–823). We also found that the exit from MI lagged, by more than 30 minutes, behind the time of lowest H1 kinase activity, whereas the two events took place concomitantly at the end of meiosis II and mitosis. Consequently, the H1 kinase activity was already increasing during the first meiotic division. When H1 kinase activation at MII was delayed by a transient inhibition of protein synthesis after GVBD, oocytes were able to support formation of interphase nuclei and DNA replication between the first meiotic division and the MII arrest, indicating that the cell cycle entered S-phase between meiosis I and meiosis II. These results strongly suggest that the machinery required for entering S-phase has been established in maturing oocytes by the end of meiosis I.(ABSTRACT TRUNCATED AT 250 WORDS)
16
Lowther, Katie M., Viacheslav O. Nikolaev, and Lisa M. Mehlmann. "Endocytosis in the mouse oocyte and its contribution to cAMP signaling during meiotic arrest." REPRODUCTION 141, no. 6 (June 2011): 737–47. http://dx.doi.org/10.1530/rep-10-0461.
Full textAbstract:
Mammalian oocytes are arrested at prophase I of meiosis until a preovulatory surge of LH stimulates them to resume meiosis. Prior to the LH surge, high levels of cAMP within the oocyte maintain meiotic arrest; this cAMP is generated in the oocyte through the activity of the constitutively active, Gs-coupled receptor, G-protein-coupled receptor 3 (GPR3) or GPR12. Activated GPRs are typically targeted for desensitization through receptor-mediated endocytosis, but a continuously high level of cAMP is needed for meiotic arrest. The aim of this study was to examine whether receptor-mediated endocytosis occurs in the mouse oocyte and whether this could affect the maintenance of meiotic arrest. We found that constitutive endocytosis occurs in the mouse oocyte. Inhibitors of receptor-mediated endocytosis, monodansylcadaverine and dynasore, inhibited the formation of early endosomes and completely inhibited spontaneous meiotic resumption. A red fluorescent protein-tagged GPR3 localized in the plasma membrane and within early endosomes in the oocyte, demonstrating that GPR3 is endocytosed. However, overexpression of G-protein receptor kinase 2 and β-arrestin-2 had only a modest effect on stimulating meiotic resumption, suggesting that these proteins do not play a major role in GPR3 endocytosis. Inhibition of endocytosis elevated cAMP levels within oocytes, suggesting that there is an accumulation of GPR3 at the plasma membrane. These results show that endocytosis occurs in the oocyte, leading to a decrease in cAMP production, and suggest that there is a balance between cAMP production and degradation in the arrested oocyte that maintains cAMP levels at an appropriate level during the maintenance of meiotic arrest.
17
Ahmed, Noreen T., David Bungard, Marcus E. Shin, Michael Moore, and Edward Winter. "The Ime2 Protein Kinase Enhances the Disassociation of the Sum1 Repressor from Middle Meiotic Promoters." Molecular and Cellular Biology 29, no. 16 (June 15, 2009): 4352–62. http://dx.doi.org/10.1128/mcb.00305-09.
Full textAbstract:
ABSTRACT Meiotic development in Saccharomyces cerevisiae (sporulation) is controlled by the sequential transcription of temporally distinct sets of meiosis-specific genes. The induction of middle genes controls exit from meiotic prophase, the completion of the nuclear divisions, and spore formation. Middle promoters are controlled through DNA elements termed middle sporulation elements (MSEs) that are bound by the Sum1 repressor during vegetative growth and by the Ndt80 activator during meiosis. It has been proposed that the induction of middle promoters is controlled by competition between Ndt80 and Sum1 for MSE occupancy. Here, we show that the Sum1 repressor can be removed from middle promoters in meiotic cells independent of Ndt80 expression. This process requires the phosphorylation of Sum1 by the meiosis-specific cyclin-dependent kinase-like kinase Ime2. The deletion of HST1, which encodes a Sir2 paralog that interacts with Sum1, bypasses the requirement for this phosphorylation. These findings suggest that in the presence of Ndt80, Sum1 may be displaced from MSEs through a competition-based mechanism but that in the absence of Ndt80, Sum1 is removed from chromatin in a separate pathway requiring the phosphorylation of Sum1 by Ime2 and the inhibition of Hst1.
18
Němeček, David, Eva Chmelikova, Jaroslav Petr, Tomas Kott, and Markéta Sedmíková. "The effect of carbon monoxide on meiotic maturation of porcine oocytes." PeerJ 9 (March 23, 2021): e10636. http://dx.doi.org/10.7717/peerj.10636.
Full textAbstract:
Oxidative stress impairs the correct course of meiotic maturation, and it is known that the oocytes are exposed to increased oxidative stress during meiotic maturation in in vitro conditions. Thus, reduction of oxidative stress can lead to improved quality of cultured oocytes. The gasotransmitter carbon monoxide (CO) has a cytoprotective effect in somatic cells. The CO is produced in cells by the enzyme heme oxygenase (HO) and the heme oxygenase/carbon monoxide (HO/CO) pathway has been shown to have an antioxidant effect in somatic cells. It has not yet been investigated whether the CO has an antioxidant effect in oocytes as well. We assessed the level of expression of HO mRNA, using reverse transcription polymerase chain reaction. The HO protein localization was evaluated by the immunocytochemical method. The influence of CO or HO inhibition on meiotic maturation was evaluated in oocytes cultured in a culture medium containing CO donor (CORM-2 or CORM-A1) or HO inhibitor Zn-protoporphyrin IX (Zn-PP IX). Detection of reactive oxygen species (ROS) was performed using the oxidant-sensing probe 2′,7′-dichlorodihydrofluorescein diacetate. We demonstrated the expression of mRNA and proteins of both HO isoforms in porcine oocytes during meiotic maturation. The inhibition of HO enzymes by Zn-PP IX did not affect meiotic maturation. CO delivered by CORM-2 or CORM-A1 donors led to a reduction in the level of ROS in the oocytes during meiotic maturation. However, exogenously delivered CO also inhibited meiotic maturation, especially at higher concentrations. In summary, the CO signaling molecule has antioxidant properties in porcine oocytes and may also be involved in the regulation of meiotic maturation.
19
Ziesel, Andrew, Qixuan Weng, Jasvinder S. Ahuja, Abhishek Bhattacharya, Raunak Dutta, Evan Cheng, G. Valentin Börner, Michael Lichten, and Nancy M. Hollingsworth. "Rad51-mediated interhomolog recombination during budding yeast meiosis is promoted by the meiotic recombination checkpoint and the conserved Pif1 helicase." PLOS Genetics 18, no. 12 (December 12, 2022): e1010407. http://dx.doi.org/10.1371/journal.pgen.1010407.
Full textAbstract:
During meiosis, recombination between homologous chromosomes (homologs) generates crossovers that promote proper segregation at the first meiotic division. Recombination is initiated by Spo11-catalyzed DNA double strand breaks (DSBs). 5’ end resection of the DSBs creates 3’ single strand tails that two recombinases, Rad51 and Dmc1, bind to form presynaptic filaments that search for homology, mediate strand invasion and generate displacement loops (D-loops). D-loop processing then forms crossover and non-crossover recombinants. Meiotic recombination occurs in two temporally distinct phases. During Phase 1, Rad51 is inhibited and Dmc1 mediates the interhomolog recombination that promotes homolog synapsis. In Phase 2, Rad51 becomes active and functions with Rad54 to repair residual DSBs, making increasing use of sister chromatids. The transition from Phase 1 to Phase 2 is controlled by the meiotic recombination checkpoint through the meiosis-specific effector kinase Mek1. This work shows that constitutive activation of Rad51 in Phase 1 results in a subset of DSBs being repaired by a Rad51-mediated interhomolog recombination pathway that is distinct from that of Dmc1. Strand invasion intermediates generated by Rad51 require more time to be processed into recombinants, resulting in a meiotic recombination checkpoint delay in prophase I. Without the checkpoint, Rad51-generated intermediates are more likely to involve a sister chromatid, thereby increasing Meiosis I chromosome nondisjunction. This Rad51 interhomolog recombination pathway is specifically promoted by the conserved 5’-3’ helicase PIF1 and its paralog, RRM3 and requires Pif1 helicase activity and its interaction with PCNA. This work demonstrates that (1) inhibition of Rad51 during Phase 1 is important to prevent competition with Dmc1 for DSB repair, (2) Rad51-mediated meiotic recombination intermediates are initially processed differently than those made by Dmc1, and (3) the meiotic recombination checkpoint provides time during prophase 1 for processing of Rad51-generated recombination intermediates.
20
Oishi, Isao, Kenji Iwai, Yukiko Kagohashi, Hiroko Fujimoto, Ken-Ichi Kariya, Tohru Kataoka, Hitoshi Sawa, et al. "Critical Role of Caenorhabditis elegansHomologs of Cds1 (Chk2)-Related Kinases in Meiotic Recombination." Molecular and Cellular Biology 21, no. 4 (February 15, 2001): 1329–35. http://dx.doi.org/10.1128/mcb.21.4.1329-1335.2001.
Full textAbstract:
ABSTRACT Although chromosomal segregation at meiosis I is the critical process for genetic reassortment and inheritance, little is known about molecules involved in this process in metazoa. Here we show by utilizing double-stranded RNA (dsRNA)-mediated genetic interference that novel protein kinases (Ce-CDS-1 and Ce-CDS-2) related to Cds1 (Chk2) play an essential role in meiotic recombination inCaenorhabditis elegans. Injection of dsRNA into adult animals resulted in the inhibition of meiotic crossing over and induced the loss of chiasmata at diakinesis in oocytes of F1animals. However, electron microscopic analysis revealed that synaptonemal complex formation in pachytene nuclei of the same progeny of injected animals appeared to be normal. Thus, Ce-CDS-1 and Ce-CDS-2 are the first example of Cds1-related kinases that are required for meiotic recombination in multicellular organisms.
21
Hanna, C. B., T. M. Glover, and C. R. Long. "246 INDUCTION OF MEIOTIC ARREST IN IMMATURE FELINE OOCYTES WITH ROSCOVITINE AND DIBUTYRYL CYCLIC-AMP." Reproduction, Fertility and Development 21, no. 1 (2009): 221. http://dx.doi.org/10.1071/rdv21n1ab246.
Full textAbstract:
Successful application of some assisted reproduction technologies in feline species requires the use of competent, meiotically mature ova, which can be difficult to obtain in sufficient quantities. Meiotic arrest of immature feline oocytes would allow the accumulation of oocytes over time to maximize laboratory resources. Two meiosis inhibitors commonly used in other species, roscovitine (ROS) and dbcAMP, were evaluated for the ability to maintain a germinal vesicle (GV) in immature feline oocytes after 24 h of in vitro culture. Feline ovaries were obtained from routine ovariohysterectomies and oocytes with homogenous cytoplasm and at least 2 layers of cumulus cells were selected. All oocytes were cultured in a basic medium modified from Gomez et al. (2000 Reprod. Fertil. Dev.) consisting of TCM-199 with Earle’s salts, 0.3% fraction V bovine serum albumin, 2.0 mm L-glutamine, 1.12 mm L-cysteine, 2.2 mm calcium lactate, 0.36 mm sodium pyruvate, 100 μm cysteamine, 10 ng μL–1 epidermal growth factor, 1 μg mL–1 estradiol, and 50 μg mL–1 gentamicin, with or without meiotic inhibitor. After 24 h of culture, cumulus cells were removed; oocytes were fixed, permeabilized, and stained with 5 μg mL–1 of Hoechst 33342; and chromatin configuration was assessed under ultraviolet fluorescence. In 4 replicates of Experiment 1, oocytes were cultured with either 25 nm ROS, 1 mm dbcAMP, both ROS and dbcAMP (Both), or without inhibitor (Control). A greater proportion of oocytes retained the GV when cultured with Both compared with ROS, dbcAMP, or Control (90.6, 67.8, 25.0, and 14.8%, respectively; chi-square P < 0.05), and ROS alone was superior to dbcAMP or Control. Culture of oocytes in the base medium plus 0.5 IU mL–1 eCG and 1.0 IU mL–1 hCG after arrest showed that pretreatment with Both did not decrease their ability to resume meiosis (87.9 v. 87.0%, respectively). Given the low percentage of oocytes with a retained GV in the presence of 1.0 mm dbcAMP, Experiment 2 evaluated the concentration of dbcAMP required to inhibit meiosis. Oocytes were cultured over 4 replicates in the base media containing 0, 0.1, 0.5, 1.0, 2.0, and 10.0 mm dbcAMP. After 24 h of culture, a greater number of oocytes were arrested at the GV stage when cultured in 10 mM dbcAMP (39.8%) than in 0, 0.1, 1.0, and 2.0 mM dbcAMP (22.0, 20.4, 25.8, and 26.3%, respectively; Fisher’s exact test P < 0.05), but there was no difference from those cultured in 0.5 mm dbcAMP (28.1%). For many species, 1.0 mm dbcAMP is commonly used to inhibit meiosis successfully for 24 h. However, dbcAMP alone did not effectively arrest meiosis, but when combined with ROS, it tended to improve meiotic arrest. Experiment 2 indicates that at least 10.0 mm dbcAMP is required to show a significant effect of meiotic inhibition in feline oocytes. Under these culture conditions, dbcAMP at levels up to 10 mm were not effective at inducing meiotic arrest. Interestingly, ROS and dbcAMP may act synergistically to successfully induce a reversible inhibition of meiosis in a high percentage of feline oocytes.
22
Hajra, Sudip, Debabrata Das, Pritha Ghosh, Soumojit Pal, Poulomi Nath, and Sudipta Maitra. "Regulation of recombinant human insulin-induced maturational events in Clarias batrachus (L.) oocytes in vitro." Zygote 24, no. 2 (February 24, 2015): 181–94. http://dx.doi.org/10.1017/s0967199415000015.
Full textAbstract:
SummaryRegulation of insulin-mediated resumption of meiotic maturation in catfish oocytes was investigated. Insulin stimulation of post-vitellogenic oocytes promotes the synthesis of cyclin B, histone H1 kinase activation and a germinal vesicle breakdown (GVBD) response in a dose-dependent and duration-dependent manner. The PI3K inhibitor wortmannin abrogates recombinant human (rh)-insulin action on histone H1 kinase activation and meiotic G2–M1 transition in denuded and follicle-enclosed oocytes in vitro. While the translational inhibitor cycloheximide attenuates rh-insulin action, priming with transcriptional blocker actinomycin D prevents insulin-stimulated maturational response appreciably, albeit in low amounts. Compared with rh-insulin, human chorionic gonadotrophin (hCG) stimulation of follicle-enclosed oocytes in vitro triggers a sharp increase in 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DHP) secreted in the incubation medium at 12 h. Interestingly, the insulin, but not the hCG-induced, maturational response shows less susceptibility to steroidogenesis inhibitors, trilostane or dl-aminoglutethimide. In addition, priming with phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) or cell-permeable dbcAMP or adenylyl cyclase activator forskolin reverses the action of insulin on meiotic G2–M1 transition. Conversely, the adenylyl cyclase inhibitor, SQ 22536, or PKA inhibitor H89 promotes the resumption of meiosis alone and further potentiates the GVBD response in the presence of rh-insulin. Furthermore, insulin-mediated meiotic maturation involves the down-regulation of endogenous protein kinase A (PKA) activity in a manner sensitive to PI3K activation, suggesting potential involvement of a cross-talk between cAMP/PKA and insulin-mediated signalling cascade in catfish oocytes in vitro. Taken together, these results suggest that rh-insulin regulation of the maturational response in C. batrachus oocytes involves down-regulation of PKA, synthesis of cyclin B, and histone H1 kinase activation and demonstrates reduced sensitivity to steroidogenesis and transcriptional inhibition.
23
Vidan, S., and A. P. Mitchell. "Stimulation of yeast meiotic gene expression by the glucose-repressible protein kinase Rim15p." Molecular and Cellular Biology 17, no. 5 (May 1997): 2688–97. http://dx.doi.org/10.1128/mcb.17.5.2688.
Full textAbstract:
The Saccharomyces cerevisiae RIM15 gene was identified previously through a mutation that caused reduced ability to undergo meiosis. We report here an analysis of the cloned RIM15 gene, which specifies a 1,770-residue polypeptide with homology to serine/threonine protein kinases. Rim15p is most closely related to Schizosaccharomyces pombe cek1+. Analysis of epitope-tagged derivatives indicates that Rim15p has autophosphorylation activity. Deletion of RIM15 causes reduced expression of several early meiotic genes (IME2, SPO13, and HOP1) and of IME1, which specifies an activator of early meiotic genes. However, overexpression of IME1 does not permit full expression of early meiotic genes in a rim15delta mutant. Ime1p activates early meiotic genes through its interaction with Ume6p, and analysis of Rim15p-dependent regulatory sites at the IME2 promoter indicates that activation through Ume6p is defective. Two-hybrid interaction assays suggest that Ime1p-Ume6p interaction is diminished in a rim15 mutant. Glucose inhibits Ime1p-Ume6p interaction, and we find that Rim15p accumulation is repressed in glucose-grown cells. Thus, glucose repression of Rim15p may be responsible for glucose inhibition of Ime1p-Ume6p interaction.
24
Dolci, S., and M. De Felici. "A study of meiosis in chimeric mouse fetal gonads." Development 109, no. 1 (May 1, 1990): 37–40. http://dx.doi.org/10.1242/dev.109.1.37.
Full textAbstract:
The influence of somatic environment on the onset and progression of meiosis in fetal germ cells was studied in chimeric gonads produced in vitro by dissociation-reaggregation experiments. Germ cells isolated from testes or ovaries of 11.5-13.5 days post coitum (dpc) CD-1 mouse embryos were loaded with the fluorescent supravital dye 5–6 carboxyfluorescein diacetate succinimyl ester (CFSE) and mixed with a cell suspension obtained by trypsin-EDTA treatment of gonads of various ages and of the same or opposite sex. Whereas 11.5 dpc donor germ cells appeared unable to survive in the chimeric gonads obtained, about 76% of the CFSE-labeled female germ cells obtained from 12.5 dpc donor embryos (premeiotic germ cells) found viable within host ovarian tissues showed a meiotic nucleus. In contrast, a smaller number (about 19%) were in meiosis in chimeric testes. None or very few of donor male germ cells entered meiosis in testes or ovarian host tissues. Aggregation of meiotic 13.5 dpc female germ cells with testis tissues from 13.5 to 14.5 dpc embryos resulted in inhibition of meiotic progression and pyknosis in most donor germ cells. These results support the existence of a meiosis-preventing substance or a factor causing oocyte degeneration in the fetal mouse testis, but not of a meiosis-inducing substance in the fetal ovary.
25
Colaiácovo, M. P., G. M. Stanfield, K. C. Reddy, V. Reinke, S. K. Kim, and A. M. Villeneuve. "A Targeted RNAi Screen for Genes Involved in Chromosome Morphogenesis and Nuclear Organization in theCaenorhabditis elegansGermline." Genetics 162, no. 1 (September 1, 2002): 113–28. http://dx.doi.org/10.1093/genetics/162.1.113.
Full textAbstract:
AbstractWe have implemented a functional genomics strategy to identify genes involved in chromosome morphogenesis and nuclear organization during meiotic prophase in the Caenorhabditis elegans germline. This approach took advantage of a gene-expression survey that used DNA microarray technology to identify genes preferentially expressed in the germline. We defined a subset of 192 germline-enriched genes whose expression profiles were similar to those of previously identified meiosis genes and designed a screen to identify genes for which inhibition by RNA interference (RNAi) elicited defects in function or development of the germline. We obtained strong germline phenotypes for 27% of the genes tested, indicating that this targeted approach greatly enriched for genes that function in the germline. In addition to genes involved in key meiotic prophase events, we identified genes involved in meiotic progression, germline proliferation, and chromosome organization and/or segregation during mitotic growth.
26
Amale, M. H., A. Z. Shahneh, and S. Nasrollahi. "Effects of nitric oxide synthase inhibition on goat oocyte meiotic maturation." Archives Animal Breeding 56, no. 1 (October 10, 2013): 255–63. http://dx.doi.org/10.7482/0003-9438-56-025.
Full textAbstract:
Abstract. Nitric oxide is a biological signalling molecule that plays a crucial role in oocyte maturation of mammalians. It is generated by the nitric oxide synthase enzyme from L-arginine. In this study we assessed the effect of nitric oxide synthase inhibition by Nω-nitro-L-arginine methyl ester (L-NAME) on meiotic maturation of goat oocytes. So, different concentrations of L-NAME (0.1, 1, 10 mM) were added to the maturation medium to evaluate the effect of inhibiting nitric oxide synthase on cumulus expansion and meiotic resumption of goat oocytes. The results showed that none of the concentrations affected cumulus expansion but the formation of the first polar body of the oocytes was suppressed in a dose dependent manner. The highest inhibitory effect was observed with 10 mM L-NAME. Moreover, to confirm the results and to evaluate whether this effect is reversible, 0.1 mM sodium nitroprusside (a nitric oxide donor) was added only to the maturation medium which had the highest concentration of L-NAME (10 mM). The concomitant addition of nitric oxide synthase inhibitor with nitric oxide donor reversed the inhibitory effect of L-NAME on meiotic maturation. These results indicated that the nitric oxide / nitric oxide synthase system is involved in the maturation of goat oocytes and that nitric oxide requirement for nuclear maturation is higher than that for cumulus expansion.
27
Petr, J., E. Chmelíková, K. Kheilová, and F. Jílek. "Histone deacetylase inhibition improves meiotic competence but not developmental competence in growing pig oocytes." Zygote 17, no. 4 (May 22, 2009): 307–14. http://dx.doi.org/10.1017/s0967199409005437.
Full textAbstract:
SummaryIn fully grown pig oocytes, meiotic maturation in vitro is retarded by inhibition of histone deacetylases by trichostatin A (TSA). In growing oocytes with partial meiotic competence, culture with TSA has no significant effect on the meiotic maturation. Growing oocytes treated with TSA mature mainly to metaphase I. The ratio of oocytes that mature to metaphase II is very limited. After transient exposure to TSA, the maturation of growing oocytes with partial meiotic competence takes a different course. When these oocytes are first cultured in a TSA-free medium, then cultured for another 24 h with 100 nM TSA and finally again in a TSA-free medium for 24 h, the ratio of oocytes that mature to metaphase II significantly increases reaching 59%. When oocytes were cultured for the same length of time without transient exposure to TSA, only 19% matured to metaphase II. Those oocytes that matured to metaphase II after transient exposure to TSA were successfully activated using calcium ionophore. However, the subsequent cleavage was very limited. We can conclude that transient exposure of growing pig oocytes with partial meiotic competence to TSA increases oocyte meiotic competence, but it does not enhance developmental competence after parthenogenetic activation.
28
Liang, Cheng-Guang, Li-Jun Huo, Zhi-Sheng Zhong, Da-Yuan Chen, Heide Schatten, and Qing-Yuan Sun. "Cyclic Adenosine 3′,5′-Monophosphate-Dependent Activation of Mitogen-Activated Protein Kinase in Cumulus Cells Is Essential for Germinal Vesicle Breakdown of Porcine Cumulus-Enclosed Oocytes." Endocrinology 146, no. 10 (October 1, 2005): 4437–44. http://dx.doi.org/10.1210/en.2005-0309.
Full textAbstract:
MAPK plays an important role during meiotic maturation in mammalian oocytes, whereas the necessity of MAPK during meiotic resumption in porcine oocytes is still controversial. Here, by applying the method of ultracentrifugation to move the opaque lipid droplets to the edge of the oocyte, therefore allowing clear visualization of porcine germinal vesicles, oocytes just before germinal vesicle breakdown (GVBD) and those that had just undergone GVBD were selected for the assay of MAPK activation. Our results showed that phosphorylation of MAPK in oocytes occurred after GVBD in all three different culture models: spontaneous maturation model, inhibition-induction maturation model, and normal maturation model. Moreover, we found that activation of MAPK in cumulus cells but not in oocytes was essential for GVBD in cumulus-enclosed oocytes. Then the cross-talk between cAMP and MAPK in cumulus cells was investigated by using cell-type-specific phosphodiesterase (PDE) isoenzyme inhibitors. Our results showed that PDE3 subtype existed in oocytes, whereas PDE4 subtype existed in cumulus cells. PDE3 inhibitor prevented meiotic resumption of oocytes, whereas PDE4 inhibitor enhanced the ability of FSH or forskolin to activate MAPK in cumulus cells. We propose that increased cAMP resulting from inhibition of PDE3 in oocytes blocks GVBD, whereas increased cAMP resulting from inhibition of PDE4 activates MAPK pathway in cumulus cells, which is essential for GVBD induction.
29
Peng, Lei, Yijing He, Weihan Wang, Yajie Chu, Qixin Lin, Rong Rui, Qiao Li, and Shiqiang Ju. "PAK1 Is Involved in the Spindle Assembly during the First Meiotic Division in Porcine Oocytes." International Journal of Molecular Sciences 24, no. 2 (January 6, 2023): 1123. http://dx.doi.org/10.3390/ijms24021123.
Full textAbstract:
P21-activated kinase 1 (PAK1), as a member of the PAK family, has been implicated in various functions during somatic mitosis; however, less is known about its role during oocyte meiosis. Herein, we highlight the indispensable role of PAK1 in regulating spindle assembly and cell cycle progression during the first meiotic division of porcine oocytes. First, we found that the activated PAK1 expressed dynamically, and its subcellular localization was tightly associated with the spindle dynamics during meiosis in porcine oocytes. Specific inhibition of PAK1 activity by inhibitor targeting PAK1 activation-3 (IPA-3) led to impaired extrusion of the first polar body (PB1); with most of the IPA-3-treated oocytes arrested at germinal vesicle breakdown (GVBD) and subjected to failure of bipolar spindle formation. However, the adverse effects caused by IPA-3 on oocytes could be restored by reducing disulfide bonds between PAK1 and IPA-3 with dithiothreitol (DTT) treatment. Furthermore, the co-immunoprecipitation assay revealed that PAK1 interacted directly with Aurora A and transforming acidic coiled coil 3 (TACC3), providing an additional explanation for the similar localization of Aurora A and activated PAK1. Additionally, inhibiting the activity of PAK1 decreased the expression of p-Aurora A and p-TACC3; however, the reduced activity of Aurora A and TACC3 could be restored by DTT. In conclusion, PAK1 plays a crucial role in the proper assembly of the spindle during the first meiotic division of porcine oocytes, and the regulation of PAK1 is associated with its effects on p-Aurora A and p-TACC3 expression.
30
Adona, Paulo Roberto, and Cláudia Lima Verde Leal. "Meiotic inhibition with different cyclin-dependent kinase inhibitors in bovine oocytes and its effects on maturation and embryo development." Zygote 12, no. 3 (August 2004): 197–204. http://dx.doi.org/10.1017/s0967199404002771.
Full textAbstract:
Cyclin-dependent kinase inhibitors (CDKIs) such as butyrolactone I (BL-I) and roscovitine (ROS) maintain bovine oocytes blocked at the germinal vesicle (GV) stage. Bohemine (BOH), another CDKI, has been used for oocyte activation. The objective of this study was to determine whether BOH blocks meiosis and to compare its efficiency with other CDKIs (ROS and BL-I). Oocytes were cultured for 24 h in 0, 50, 100 and 150 μM BOH to determine the best concentration for blocking meiosis (experiment 1). GV rates were 3.3%, 64.5%, 83.3% and 88.9% (0, 50, 100 and 150 μM, respectively). Experiment 2 compared meiotic inhibition efficiency of BOH (100 μM), ROS (25 μM) and BL-I (100 μM). BL-I presented the highest GV rates (97.5%). BOH and ROS were similar to each other (85.4% and 79.9%, respectively). To assess the reversibility of meiotic inhibition (experiment 3), oocytes underwent in vitro maturation (IVM) for 18 h after the 24 h inhibition. Control oocytes were submitted to IVM for 18 h (C18) or 24 h (C24). Maturation rates were either similar to (ROS and BL-I: 96.0% and 93.6%, respectively) or superior to (BOH, 96.9%) C24 (91.0%). All groups were superior to C18 (82.5%). In experiment 4, oocytes were treated as in experiment 3 and then in vitro fertilized and cultured for 8 days. Blastocyst rates for BL-I (32.3%) were similar to C24 (35.0%), while those for BOH (20.2%) and ROS (24.2%) were inferior. All groups were inferior to C18 (43.4%). The results show that: (a) BOH inhibits meiosis resumption; (b) BL-I is the most effective of the CDKIs tested for blocking meiosis; (c) culture of oocytes with meiosis inhibitors is fully reversible in terms of nuclear maturation but they may either decrease (BOH and ROS) or maintain (BL-I) embryo development rates.
31
Bilodeau-Goeseels, Sylvie, Nora Magyara, and Coralie Collignon. "Characterization of the effects of metformin on porcine oocyte meiosis and on AMP-activated protein kinase activation in oocytes and cumulus cells." Zygote 22, no. 2 (April 12, 2013): 275–85. http://dx.doi.org/10.1017/s0967199413000075.
Full textAbstract:
SummaryThe adenosine monophosphate-activated protein kinase (AMPK) activators 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR) and metformin (MET) inhibit resumption of meiosis in porcine cumulus-enclosed oocytes. The objective of this study was to characterize the inhibitory effect of MET on porcine oocyte meiosis by: (1) determining the effects of an AMPK inhibitor and of inhibitors of signalling pathways involved in MET-induced AMPK activation in other cell types on MET-mediated meiotic arrest in porcine cumulus-enclosed oocytes; (2) determining whether MET and AICAR treatments lead to increased activation of porcine oocyte and/or cumulus cell AMPK as measured by phosphorylation of its substrate acetyl-CoA carboxylase; and (3) determining the effects of inhibition of the AMPK kinase, Ca2+/calmodulin-dependent protein kinase kinase (CaMKK), and Ca2+ chelation on oocyte meiotic maturation and AMPK activation in porcine oocytes and cumulus cells. The AMPK inhibitor compound C (CC; 1 μM) did not reverse the inhibitory effect of AICAR (1 mM) and MET (2 mM) on porcine oocyte meiosis. Additionally, CC had a significant inhibitory effect on its own. eNOS, c-Src and PI-3 kinase pathway inhibitors did not reverse the effect of metformin on porcine oocyte meiosis. The level of acetyl-CoA carboxylase (ACC) phosphorylation in oocytes and cumulus cells did not change in response to culture in the presence of MET, AICAR, CC, the CaMKK inhibitor STO-609 or the Ca2+ chelator BAPTA-AM for 3 h, but STO-609 increased the percentage of porcine cumulus-enclosed oocytes (CEO) that remained at the germinal vesicle (GV) stage after 24 h of culture. These results indicate that the inhibitory effect of MET and AICAR on porcine oocyte meiosis was probably not mediated through activation of AMPK.
32
Bury, Leah, Paula A. Coelho, Angela Simeone, Samantha Ferries, Claire E. Eyers, Patrick A. Eyers, Magdalena Zernicka-Goetz, and David M. Glover. "Plk4 and Aurora A cooperate in the initiation of acentriolar spindle assembly in mammalian oocytes." Journal of Cell Biology 216, no. 11 (September 28, 2017): 3571–90. http://dx.doi.org/10.1083/jcb.201606077.
Full textAbstract:
Establishing the bipolar spindle in mammalian oocytes after their prolonged arrest is crucial for meiotic fidelity and subsequent development. In contrast to somatic cells, the first meiotic spindle assembles in the absence of centriole-containing centrosomes. Ran-GTP can promote microtubule nucleation near chromatin, but additional unidentified factors are postulated for the activity of multiple acentriolar microtubule organizing centers in the oocyte. We now demonstrate that partially overlapping, nonredundant functions of Aurora A and Plk4 kinases contribute to initiate acentriolar meiosis I spindle formation. Loss of microtubule nucleation after simultaneous chemical inhibition of both kinases can be significantly rescued by drug-resistant Aurora A alone. Drug-resistant Plk4 can enhance Aurora A–mediated rescue, and, accordingly, Plk4 can phosphorylate and potentiate the activity of Aurora A in vitro. Both kinases function distinctly from Ran, which amplifies microtubule growth. We conclude that Aurora A and Plk4 are rate-limiting factors contributing to microtubule growth as the acentriolar oocyte resumes meiosis.
33
Arévalo-Rodríguez, Miguel, and Joseph Heitman. "Cyclophilin A Is Localized to the Nucleus and Controls Meiosis in Saccharomyces cerevisiae." Eukaryotic Cell 4, no. 1 (January 2005): 17–29. http://dx.doi.org/10.1128/ec.4.1.17-29.2005.
Full textAbstract:
ABSTRACT Cyclophilin A is conserved from yeast to humans and mediates the ability of cyclosporine to perturb signal transduction cascades via inhibition of calcineurin. Cyclophilin A also catalyzes cis-trans peptidyl-prolyl isomerization during protein folding or conformational changes; however, cyclophilin A is not essential in yeast or human cells, and the true biological functions of this highly conserved enzyme have remained enigmatic. In Saccharomyces cerevisiae, cyclophilin A becomes essential in cells compromised for the nuclear prolyl-isomerase Ess1, and cyclophilin A physically interacts with two nuclear histone deacetylase complexes, Sin3-Rpd3 and Set3C, which both control meiosis. Here we show that cyclophilin A is localized to the nucleus in yeast cells and governs the meiotic gene program to promote efficient sporulation. The prolyl-isomerase activity of cyclophilin A is required for this meiotic function. We document that cyclophilin A physically associates with the Set3C histone deacetylase and analyze in detail the structure of this protein-protein complex. Genetic studies support a model in which cyclophilin A controls meiosis via Set3C and an additional target. Our findings reveal a novel nuclear role for cyclophilin A in governing the transcriptional program required for the vegetative to meiotic developmental switch in budding yeast.
34
Ellefson, Marina L., and Francis J. McNally. "CDK-1 inhibits meiotic spindle shortening and dynein-dependent spindle rotation in C. elegans." Journal of Cell Biology 193, no. 7 (June 20, 2011): 1229–44. http://dx.doi.org/10.1083/jcb.201104008.
Full textAbstract:
In animals, the female meiotic spindle is positioned at the egg cortex in a perpendicular orientation to facilitate the disposal of half of the chromosomes into a polar body. In Caenorhabditis elegans, the metaphase spindle lies parallel to the cortex, dynein is dispersed on the spindle, and the dynein activators ASPM-1 and LIN-5 are concentrated at spindle poles. Anaphase-promoting complex (APC) activation results in dynein accumulation at spindle poles and dynein-dependent rotation of one spindle pole to the cortex, resulting in perpendicular orientation. To test whether the APC initiates spindle rotation through cyclin B–CDK-1 inactivation, separase activation, or degradation of an unknown dynein inhibitor, CDK-1 was inhibited with purvalanol A in metaphase-I–arrested, APC-depleted embryos. CDK-1 inhibition resulted in the accumulation of dynein at spindle poles and dynein-dependent spindle rotation without chromosome separation. These results suggest that CDK-1 blocks rotation by inhibiting dynein association with microtubules and with LIN-5–ASPM-1 at meiotic spindle poles and that the APC promotes spindle rotation by inhibiting CDK-1.
35
Ashkenazi, H., X. Cao, S. Motola, M. Popliker, M. Conti, and A. Tsafriri. "Epidermal Growth Factor Family Members: Endogenous Mediators of the Ovulatory Response." Endocrinology 146, no. 1 (January 1, 2005): 77–84. http://dx.doi.org/10.1210/en.2004-0588.
Full textAbstract:
Previous studies showed that epidermal growth factor (EGF) and TGFα mimic the action of LH on the resumption of oocyte maturation. We tested whether EGF-like agents, such as amphiregulin (AR), epiregulin (ER), and betacellulin (BTC), also mediate the LH stimulation of the ovulatory response in the rat. LH induced transient follicular expression of AR, ER, and BTC mRNA, reaching a maximum after 3-h incubation. Furthermore, the addition of ER, AR, and BTC to the culture medium could mimic some of LH actions. AR and ER fully simulated LH-induced resumption of meiosis in vitro, whereas BTC was less effective. To study the putative involvement of EGF-like factors in mediation of LH signal, the effect of the EGF receptor kinase inhibitor AG1478 was tested. When added with LH, AG1478, but not its inactive analog AG43, reduced EGF receptor phosphorylation and oocyte maturation compared with follicles treated with LH only. In addition to the inhibition of resumption of meiosis, AG1478 administration into the bursa (3 μg/bursa) resulted in 51% (P < 0.0005) inhibition of ovulation in the treated ovaries, compared with the untreated contralateral ones, as well as to the vehicle-treated ovaries (P < 0.02). LH, as well as ER, induced the expression of genes associated with the ovulatory response like rat hyaluronan synthase-2, cycloxygenase-2, and TNFα-stimulated gene 6 mRNA, whereas AG1478 inhibited this effect of LH. Release of EGF-like factors from the membrane is dependent on activated metalloproteases. Indeed, Galardin, a broad-spectrum metalloprotease inhibitor, but not a specific matrix metalloprotease 2 and 9 inhibitor, suppressed meiotic maturation induced by LH. Conversely, meiotic maturation induced by ER was not affected by Galardin, thus, supporting the notion that LH releases follicular membrane-bound EGF-like agents. In summary, EGF-like factors such as ER, AR, and BTC seem to mediate, at least partially, the LH stimulation of oocyte maturation, ovulatory enzyme expression, and ovulation.
36
Kim, D. H., S. W. Kim, G. S. Im, B. C. Yang, D. R. Lee, H. S. Park, I. S. Hwang, J. S Seo, B. S. Yang, and W. K. Chang. "284 KINETICS OF OOCYTE MATURATION AND SUBSEQUENT DEVELOPMENT OF PARTHENOGENETIC PORCINE EMBRYOS AFTER MEIOTIC INHIBITION WITH ROSCOVITINE." Reproduction, Fertility and Development 17, no. 2 (2005): 292. http://dx.doi.org/10.1071/rdv17n2ab284.
Full textAbstract:
Maturation of mammalian oocytes is a very important process for subsequent embryo development after fertilization. Prolonged maturation time by meiotic inhibitors could be an effective method for improvement in the meiotic and developmental competence of mammalian oocytes. Roscovitine, a cyclin dependent kinase inhibitor, is known to specifically inhibit M-phase promoting factor (MPF) kinase activity and prevent the resumption of meiosis. The aim of this study was to examine the effect of roscovitine on the maturation and subsequent development of porcine oocytes. Ovaries were collected from slaughtered prepubertal gilts and COCs were aspirated from 2- to 5-mm antral follicles. In control, porcine cumulus oocyte complexes (COCs) were cultured in the maturation medium (TCM-199 supplemented with 0.3% BSA, 1 μg/mL FSH, 1 μg/mL LH, and 10 ng/mL EGF) for 44 h. In the experimental group, COCs were cultured in the inhibition medium (TCM-199 supplemented with 0.3% BSA and roscovitine) for 24 h, and then further cultured in the maturation medium for 44 h. Matured oocytes from both groups were activated by electrical pulse (1.2 kV/cm for 30 μs), and then cultured in PZM-3 medium for 6 days. Apoptotic cells in blastocysts were detected by TUNEL assay and total cell number was examined by propidium iodide (PI) counterstaining. Data were analyzed by chi-square and Student's t-test. The first experiment was conducted to determine the effect of roscovitine (0, 12.5, 25, 50, and 100 μM) on meiotic inhibition of GV oocytes. This effect was dose-dependent, and a concentration of 50 μM was sufficient to prevent meiotic resumption in 79.2% (76/96, 5 replicates) of the porcine oocytes after 24 h of culture when compared to 0 (15.4%, 15/97), 12.5 (32.1%, 36/112), 25 (57.4%, 54/94), and 100 μM (77.8%, 77/99). The second experiment was carried out to examine the kinetics of maturation of roscovitine-treated porcine oocytes. The concentration of roscovitine used was 50 μM. A total of 75.8% (50/66, 3 replicates) of roscovitine-treated oocytes reached metaphase II stage compared with 70.8% (46/65) of control. The third experiment was performed to compare embryo development between control and treated group after parthenogenetic activation. No differences (P > 0.05) were found between the control and the treated group in cleavage rate (77.2%, 132/171 vs. 68.0%, 115/169), blastocyst rate (26.9%, 46/171 vs. 17.8%, 30/169), and total (33.7 ± 12.4 vs. 35.1 ± 12.6) and apoptotic (2.2 ± 2.4 vs. 2.2 ± 1.2) cell number per blastocyst (4 replicates). The results suggest that roscovitine can be used to prolong maturation time of porcine oocytes without reducing meiotic maturation but also without significantly decreasing their subsequent developmental competence. Further studies are necessary to improve the developmental competence of porcine oocytes treated with roscovitine.
37
Nogueira, D., R. Cortvrindt, B. Everaerdt, and J. Smitz. "Effects of long-term in vitro exposure to phosphodiesterase type-3 inhibitors on follicle and oocyte development." Reproduction 130, no. 2 (August 2005): 177–86. http://dx.doi.org/10.1530/rep.1.00652.
Full textAbstract:
Germinal vesicle (GV)-stage oocytes retrieved from antral follicles undergo nuclear maturation in vitro, which typically occurs prior to cytoplasmic maturation. Short-term culture with meiotic inhibitors has been applied to arrest oocytes at the GV stage aiming to synchronize nuclear and ooplasmic maturity. However, the results obtained are still far from the in vivo situation. In order to acquire competence, immature oocytes may require meiotic arrest in vitro for a more extended period. The phosphodiesterase type 3-inhibitor (PDE3-I) is a potent meiotic arrester. The effects of a prolonged culture with PDE3-I on oocyte quality prior to and after reversal from the inhibition are not known. This study tested the impact of long-term in vitro exposure of two PDE3-Is, org9935 and cilostamide, on oocytes using a mouse follicle culture model. The results showed that PDE3-I (maximum of 10 μM) during a 12-day culture of follicle-enclosed oocytes did not alter somatic cell proliferation, differentiation or follicle survival. In addition, the steroid production profile was not significantly modified by a 12-day exposure to PDE3-I. The recombinant human chorionic gonadotrophin/recombinant human epidermal growth factor stimulus induced a characteristic normal progesterone peak of luteinization and normal mucification of the cumulus cells, while the enclosed oocyte remained blocked at the GV stage. In vitro maturation of denuded or cumulus-enclosed oocytes derived from org9935- or cilostamide-exposed follicles progressed through meiosis and formed morphologically normal meiotic spindles with chromosomes properly aligned at the equator. In conclusion, long-term culture with PDE3-I was harmless to somatic cell function, differentiation, oocyte growth and maturation. Our results suggested that PDE3-I can be applied when extended oocyte culture is required to improve ooplasmic maturation.
38
Kubiak, J., A. Paldi, M. Weber, and B. Maro. "Genetically identical parthenogenetic mouse embryos produced by inhibition of the first meiotic cleavage with cytochalasin D." Development 111, no. 3 (March 1, 1991): 763–69. http://dx.doi.org/10.1242/dev.111.3.763.
Full textAbstract:
The microfilament inhibitor cytochalasin D inhibits extrusion of the first polar body when present during the first meiotic division of mouse oocytes; however, it does not interfere with anaphase movement of chromosomes, and thus induces the formation of tetraploid oocytes. After the separation of chromosomes in anaphase, two spindles start to assemble. However, they merge rapidly and a single meiotic spindle forms. During the transition between metaphase I and metaphase II, in the presence of cytochalasin D, a drop in histone kinase activity takes place demonstrating a transitional decrease in the activity of the maturation promoting factor. These oocytes can be activated parthenogenetically a few hours after washing out the inhibitor. After completion of the second meiotic division and extrusion of a polar body, they contain a diploid number of chromosomes. They are genetically identical to each other and to their mother. Such eggs develop to the blastocyst stage and can implant in the uteri of foster mothers. Most of these fetuses die before the 9th day of gestation, as do diploid control fetuses treated with cytochalasin D during the second meiotic division. The heterozygous state of the experimental embryos obtained after activation of eggs recovered from heterozygous females and treated with cytochalasin D during the first meiotic division was confirmed using a glucose-phosphate isomerase assay. This technique allows the production of genetic clones of parthenogenetic embryos by simple means.
39
Ou, Xiang-Hong, Sen Li, Bao-Zeng Xu, Lei-Ning Chen, Man-Xi Jiang, Shao-Qin Chen, and Nan-Qiao Chen. "Mitogen-activated protein kinase-activated protein kinase 2 is a critical regulator of pig oocyte meiotic maturation." Reproduction, Fertility and Development 29, no. 2 (2017): 223. http://dx.doi.org/10.1071/rd15150.
Full textAbstract:
Mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), a direct substrate of p38 MAPK, plays key roles in multiple cellular processes. In the present study, we showed that MK2 affected not only cumulus expansion, but also the oocyte meiotic cell cycle in porcine oocytes. Inhibition of MK2 arrested oocytes at the germinal vesicle (GV) stage or the prometaphase I/metaphase I stage. Unlike in mouse oocytes, where phosphorylated (p-) MK2 was localised at the minus end of spindle microtubules and close to the spindle poles, in porcine oocytes p-MK2 was concentrated at the spindle equator and localised at the plus end of spindle microtubules. Knockdown or inhibition of MK2 resulted in spindle defects: spindles were surrounded by irregular chromosome non-disjunction or by chromosomes detached from the spindles. MK2 regulated spindle organisation and chromosome alignment by connecting microtubules with kinetochores. In addition, unlike in mitotic cells and meiotic mouse oocytes, the MK2–p38 MAPK pathway may not play an important role during meiotic cell cycle in porcine oocytes. In conclusion, MK2 is an important regulator of porcine oocyte meiotic maturation.
40
Tubman, L., A. Peter, and R. Krisher. "344 PENTOSE PHOSPHATE PATHWAY ACTIVITY CONTROLS NUCLEAR MATURATION OF PORCINE OOCYTES." Reproduction, Fertility and Development 18, no. 2 (2006): 279. http://dx.doi.org/10.1071/rdv18n2ab344.
Full textAbstract:
Diphenyleneiodonium (DPI), an inhibitor of the pentose phosphate pathway (PPP), arrests nuclear maturation of porcine oocytes. This inhibition is reversed using products or cofactors of PPP such as nicotinamide adenine dinucleotide phosphate (NADP), phosphoribose diphosphate (PRPP), and ribose-5-phosphate (R5P). The objective of this study was to determine the relationship between DPI-mediated meiotic inhibition, reversal of this inhibition, and metabolism of in vitro-matured (IVM) porcine oocytes. Oocytes were aspirated, searched, and selected in the presence of DPI, with the exception of control oocytes. Oocytes were then matured in one of five treatments for 40 h in 7% CO2 in air at 39°C in defined Purdue Porcine Medium for maturation (PPMmat). Treatments included control, 50 nM DPI (DPI), DPI + 5 mM NADP (NADP), DPI + 12.5 mM PRPP (PRPP), and DPI + 10 mM R5P (R5P). Following IVM, oocytes were denuded by vortexing. Glycolysis and PPP activities were measured in 4 μL hanging drops containing labeled glucose (0.0125 mM 5-3H glucose and 0.482 mM 1-14C glucose, respectively) for 3 h in 6% CO2. Oocytes were then individually fixed in a 3:2:1 solution of ethanol:acetic acid:chloroform and stained with aceto-orcein for determination of meiotic stage (germinal vesicle = 1 through metaphase II = 7). Data were analyzed using one-way ANOVA. The use of DPI inhibited PPP and nuclear maturation; additionally glycolysis was decreased by DPI compared to control. Addition of NADP and PRPP increased both metabolic pathways and nuclear maturation compared to DPI. R5P restored glycolysis and nuclear maturation to control levels, and PPP to above the control level. There were no significant differences among meiotic stages relative to glycolytic activity. PPP activity was significantly different (values with different superscripts; P < 0.05) among oocytes of different meiotic stages (germinal vesicle = 0.24 ± 0.03ad, germinal vesicle breakdown = 0.40 ± 0.05bcde, condensed chromatin = 0.44 ± 0.05bcd, metaphase I = 0.45 ± 0.12abcd, anaphase = 0.76 ± 0.50abcde, telophase = 0.92 ± 0.17be, metaphase II = 0.74 ± 0.08be). Percentages of oocytes reaching MII were 43.48 (control), 2.08 (DPI), 28.30 (NADP), 18.18 (PRPP), and 46.94 (R5P). These results demonstrate that the PPP is a critical control mechanism for nuclear maturation of porcine oocytes, as inhibition of this metabolic pathway resulted in arrest of nuclear maturation. Addition of PPP cofactors or end products to the arresting medium led to reversal of inhibition as demonstrated by restoration of PPP activity resulting in nuclear maturation. Table 1. Meiotic stage, glycolysis, and pentose phosphate pathway activity after in vitro maturation of porcine oocytes
41
Shuhaibar, Leia C., Jeremy R. Egbert, Rachael P. Norris, Paul D. Lampe, Viacheslav O. Nikolaev, Martin Thunemann, Lai Wen, Robert Feil, and Laurinda A. Jaffe. "Intercellular signaling via cyclic GMP diffusion through gap junctions restarts meiosis in mouse ovarian follicles." Proceedings of the National Academy of Sciences 112, no. 17 (March 16, 2015): 5527–32. http://dx.doi.org/10.1073/pnas.1423598112.
Full textAbstract:
Meiosis in mammalian oocytes is paused until luteinizing hormone (LH) activates receptors in the mural granulosa cells of the ovarian follicle. Prior work has established the central role of cyclic GMP (cGMP) from the granulosa cells in maintaining meiotic arrest, but it is not clear how binding of LH to receptors that are located up to 10 cell layers away from the oocyte lowers oocyte cGMP and restarts meiosis. Here, by visualizing intercellular trafficking of cGMP in real-time in live follicles from mice expressing a FRET sensor, we show that diffusion of cGMP through gap junctions is responsible not only for maintaining meiotic arrest, but also for rapid transmission of the signal that reinitiates meiosis from the follicle surface to the oocyte. Before LH exposure, the cGMP concentration throughout the follicle is at a uniformly high level of ∼2–4 μM. Then, within 1 min of LH application, cGMP begins to decrease in the peripheral granulosa cells. As a consequence, cGMP from the oocyte diffuses into the sink provided by the large granulosa cell volume, such that by 20 min the cGMP concentration in the follicle is uniformly low, ∼100 nM. The decrease in cGMP in the oocyte relieves the inhibition of the meiotic cell cycle. This direct demonstration that a physiological signal initiated by a stimulus in one region of an intact tissue can travel across many layers of cells via cyclic nucleotide diffusion through gap junctions could provide a general mechanism for diverse cellular processes.
42
Maziero, Rosiara Rosária Dias, Carlos Renato de Freitas Guaitolini, Daniela Martins Paschoal, André Maciel Crespilho, Bianca Andriolo Monteiro, Jonathan Soares de Lima, Danielle Andressa Oliveira Sestari, and Fernanda da Cruz Landim-Alvarenga. "Treatment with roscovitine and butyrolactone I prior to in vitro maturation alters blastocyst production." Zygote 28, no. 1 (October 11, 2019): 24–31. http://dx.doi.org/10.1017/s0967199419000571.
Full textAbstract:
SummaryThis study evaluated the effects of oocyte meiosis inhibitors roscovitine (ROS) and butyrolactone I (BL-I) on in vitro production of bovine embryos. Bovine oocytes were maintained in pre in vitro maturation (pre-IVM) with 25 µM ROS or 100 µM BL-I for 24 h to delay meiosis and for 24 h in in vitro maturation (IVM). Following this treatment, the nuclear maturation index was evaluated. All embryos degenerated following this procedure. In the second set of experiments, oocytes were maintained for 6 or 12 h in pre-IVM with the following three treatments: ROS (25 µM or 12.5 µM), BL-I (100 µM or 50 µM) or a combination of both drugs (6.25 µM ROS and 12.5 µM BL-I). Oocytes were cultivated for 18 or 12 h in IVM. When a meiosis-inducing agent was used during pre-IVM for 24 h, more degenerated oocytes were observed at the end of the IVM period. This effect decreased when the meiotic blocking period was reduced to 6 or 12 h. No significant differences were observed in the blastocyst production rate of oocytes in pre-IVM for 6 h with ROS, BL-I, or ROS + BL-I compared with that of the control group (P > 0.05). However, inhibition of oocytes for 12 h resulted in decreased embryo production compared with that in the controls (P < 0.05). There was no difference in the post-vitrification embryo re-expansion rate between the study groups, showing that the meiotic inhibition for 6 or 12 h did not alter the embryo cryopreservation process.
43
Yang, Mo, Yimei Jin, Siying Fan, Xiaoling Liang, Jialin Jia, Zhongzhou Tan, Tao Huang, Yuan Li, Teng Ma, and Mo Li. "Inhibition of neddylation causes meiotic arrest in mouse oocyte." Cell Cycle 18, no. 11 (May 21, 2019): 1254–67. http://dx.doi.org/10.1080/15384101.2019.1617453.
Full text
44
Quartuccio, Suzanne M., Shweta S. Dipali, and Karen Schindler. "Haspin inhibition reveals functional differences of interchromatid axis–localized AURKB and AURKC." Molecular Biology of the Cell 28, no. 17 (August 15, 2017): 2233–40. http://dx.doi.org/10.1091/mbc.e16-12-0850.
Full textAbstract:
Aneuploidy is the leading genetic abnormality contributing to infertility, and chromosome segregation errors are common during female mammalian meiosis I (MI). Previous results indicate that haspin kinase regulates resumption of meiosis from prophase arrest, chromosome condensation, and kinetochore–microtubule attachments during early prometaphase of MI. Here we report that haspin inhibition in late prometaphase I causes acceleration of MI, bypass of the spindle assembly checkpoint (SAC), and loss of interchromatid axis–localized Aurora kinase C. Meiotic cells contain a second chromosomal passenger complex (CPC) population, with Aurora kinase B (AURKB) bound to INCENP. Haspin inhibition in oocytes from Aurkc−/− mice, where AURKB is the sole CPC kinase, does not alter MI completion timing, and no change in localization of the SAC protein, MAD2, is observed. These data suggest that AURKB on the interchromatid axis is not needed for SAC activation and illustrate a key difference between the functional capacities of the two AURK homologues.
45
Tarsounas, M., R. E. Pearlman, and P. B. Moens. "Meiotic activation of rat pachytene spermatocytes with okadaic acid: the behaviour of synaptonemal complex components SYN1/SCP1 and COR1/SCP3." Journal of Cell Science 112, no. 4 (February 15, 1999): 423–34. http://dx.doi.org/10.1242/jcs.112.4.423.
Full textAbstract:
The phosphatase inhibitor okadaic acid accelerates meiotic events in rodent germ cells in culture. Isolated pachytene spermatocytes treated with okadaic acid proceed to a metaphase I arrest in a few hours as opposed to the similar process in vivo, which requires several days. Leptotene/zygotene spermatocytes cannot be activated in this way, suggesting that okadaic acid enables cells to bypass a sensor of the meiotic progression, which is pachytene specific. We monitored the chromosome behaviour accompanying the transition to metaphase I in rat spermatocytes with antibodies against COR1/SCP3, a component of the meiotic chromosome cores, and against the synaptic protein, SYN1/SCP1. Okadaic acid induced a rapid synaptonemal complex dissolution and bivalent separation, followed by chromosome condensation and chiasmata formation, similar to the succession of events in untreated cells. The similarity between meiosis I induced with okadaic acid and the meiosis I events in vivo extends to the dissolution of the nuclear membrane and the disappearance of the microtubule network at the onset of metaphase I. This cell culture system provides a model for the in vivo transition from pachytene to metaphase I and therefore can be used in the study of this transition at the molecular level. The effect of okadaic acid is most likely mediated by the activation of tyrosine kinases, as addition of genistein, a general tyrosine kinase inhibitor, completely abolishes the observed effect of okadaic acid on chromosome metabolism. The okadaic acid-induced progression to the metaphase I arrest is not affected by the inhibition of protein synthesis. However, pachytene spermatocytes incubated in the presence of protein synthesis inhibitors for 6 hours show loss of synapsis which is abnormal in that it is not accompanied by chiasmata formation. The two meiosis-specific proteins, SYN1/SCP1 and COR1/SCP3, are efficiently phosphorylated in vitro by extracts from isolated pachytene cells. Extracts from cells that have reached metaphase I upon okadaic acid treatment, with concomitant displacement of SYN1/SCP1 and COR1/SCP3 from their chromosomes, do not have this capability. These data support the hypothesis that phosphorylation of SYN1/SCP1 and COR1/SCP3 targets their removal from the chromosomes and that activity of the kinases involved correlates with the presence of these two proteins on the chromosomes.
46
Severance, Ashley L., and Keith E. Latham. "PLK1 regulates spindle association of phosphorylated eukaryotic translation initiation factor 4E-binding protein and spindle function in mouse oocytes." American Journal of Physiology-Cell Physiology 313, no. 5 (November 1, 2017): C501—C515. http://dx.doi.org/10.1152/ajpcell.00075.2017.
Full textAbstract:
Oocyte meiotic spindles are associated with spindle-enriched mRNAs, phosphorylated ribosome protein S6, and phosphorylated variants of the key translational regulator, eukaryotic translation initiation factor 4E-binding protein 1 (eIF4E-BP1), consistent with translational control of localized mRNAs by eIF4E-BP1 in facilitating spindle formation and stability. Using specific kinase inhibitors, we determined which kinases regulate phosphorylation status of eIF4E-BP1 associated with meiotic spindles in mouse oocytes and effects of kinase inhibition on chromosome congression and spindle formation. Neither ataxia telangiectasia-mutated kinase nor mechanistic target of rapamycin inhibition significantly affected phosphorylation status of spindle-associated eIF4E-BP1 at the phosphorylation sites examined. Spindle-associated phospho-eIF4E-BP1, spindle formation, and chromosome congression were strongly disrupted by polo-like kinase I (PLK1) inhibition at both metaphase I (MI) and MII. In addition, direct inhibition of eIF4E-BP1 via 4EGI led to spindle defects at MI, indicating a direct role for eIF4E-BP1 phosphorylation in meiotic spindle formation. PLK1 also regulated microtubule dynamics throughout the ooplasm, indicating likely coordination between spindle dynamics and broader ooplasm cytoskeletal dynamics. Because diverse upstream signaling pathways converge on PLK1, these results implicate PLK1 as a major regulatory nexus coupling endogenous and exogenous signals via eIF4E-BP1 to the regulation of spindle formation and stability.
47
Leal, C. L. V., S. Mamo, T. Fair, and P. Lonergan. "345 GENE EXPRESSION IN OOCYTES AFTER MEIOTIC INHIBITION WITH THE CYCLIN-DEPENDENT KINASE INHIBITOR BUTYROLACTONE I." Reproduction, Fertility and Development 22, no. 1 (2010): 329. http://dx.doi.org/10.1071/rdv22n1ab345.
Full textAbstract:
Once removed from the follicle, mammalian oocytes resume meiosis spontaneously and progress through breakdown of the germinal vesicle to the matured state at metaphase II. The ability to reversibly inhibit such meiotic resumption has been reported and is a potentially useful method for studying developmental competence acquisition in oocytes as well as in some cases allowing flexibility in an IVF system where oocytes are collected from distant locations or on different days. The aim of the present study was to determine the effect of temporary inhibition of meiotic resumption using the cyclin-dependent kinase inhibitor butyrolactone I (BLI) on gene expression in bovine oocytes. Immature bovine oocytes were recovered from the ovaries of slaughtered heifers at a commercial abattoir and assigned to 1 of 4 groups: (1) Control: immature oocytes were collected either immediately or (2) after IVM for 24 h in TCM-199 containing 10 ng mL-1 EGF and 10% (v/v) FCS, (3) Inhibited oocytes collected either 24 h after incubation in the presence of 100 μM BLI in TCM-199 with 3 mg mL-1 BSA or (4) after meiotic inhibition for 24 h followed by in vitro maturation. All cultures were carried out at 38.5°C under 5% CO2 in air and maximum humidity. For mRNA relative abundance analysis, cumulus cells were removed and pools of 10 denuded oocytes were snap frozen in liquid nitrogen and stored at -80°C until use. A total of 42 transcripts, previously reported to be related to cell cycle regulation and/or oocyte competence were evaluated by quantitative real time PCR. Differences in relative abundance were analyzed by ANOVA and Student’s t-test. The majority of transcripts were downregulated (P < 0.05) after IVM in control oocytes (23 out of 42) and the same pattern was observed in inhibited oocytes that were allowed to mature. Twelve transcripts remained stable (P > 0.05) after IVM in control oocytes; of these, only two (PTTG1 and INHBA) did not show the same pattern in inhibited and matured oocytes. Few genes (7) were upregulated after IVM in control oocytes (P < 0.05) and of these, three (PLAT1, RBP1, and INHBB) were not upregulated in inhibited oocytes after IVM. Inhibited oocytes showed similar levels of expression (P > 0.05) as immature control oocytes, except for two genes (LUM and INHBB), which were increased in these oocytes (P < 0.05). The expression profiles of cell cycle genes were mostly unaffected by the BLI treatment. The few genes affected were previously reported as competence-related and could be useful markers of oocyte competence following pretreatment. In conclusion, the changes occurring in transcript abundance during oocyte maturation in vitro were to a large extent mirrored following inhibition of meiotic resumption prior to IVM and subsequent release from inhibition and maturation. CLV Leal was supported by CNPq, Brazil (PDE 201487/2007-1); Supported by Science Foundation Ireland (07/SRC/B1156).
48
Kheilová, Kateřina, Jaroslav Petr, Tereza Žalmanová, Veronika Kučerová-Chrpová, and Dalibor Řehák. "Src family kinases are involved in the meiotic maturation of porcine oocytes." Reproduction, Fertility and Development 27, no. 7 (2015): 1097. http://dx.doi.org/10.1071/rd13352.
Full textAbstract:
Mammalian meiotic maturation is regulated by changes in the phosphorylation state of proteins involved in signalling pathways. The regulatory proteins include the family of Src tyrosine kinases. Src family kinases (SFKs) are required for meiotic maturation of mouse oocytes, and it remains to be elucidated whether they play the same role in porcine oocytes. To clarify the role of SFKs in the meiotic maturation of porcine oocytes we used inhibition of SFKs, western blotting and immunolocalisation to determine the presence of SFKs and localisation in the oocytes and assays to determine the activity of maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK). Inhibition of SFKs resulted in the disruption of oocyte maturation and led to a decline in MPF and MAPK activity. The fluorescence intensity of SFKs in the cytoplasm and membrane of MI oocytes decreased significantly compared with germinal vesicle oocytes. The highest fluorescence intensity for SFKs was detected on the membrane of MII oocytes. Only weak fluorescence was detected in the perichromosomal area of MI and MII oocytes. These results prove that SFKs play an active role in the meiotic maturation of porcine oocytes by regulating MPF and MAPK activity.
49
Lambie, Eric J., and G. Shirleen Roeder. "REPRESSION OF MEIOTIC CROSSING OVER BY A CENTROMERE (CEN3) IN SACCHAROMYCES CEREVISIAE." Genetics 114, no. 3 (November 1, 1986): 769–89. http://dx.doi.org/10.1093/genetics/114.3.769.
Full textAbstract:
ABSTRACT The location of the centromere of chromosome III (CEN3) of Saccharomyces cerevisiae has been altered by means of transformation. The frequency of meiotic crossing over in the CEN3-PGK1 and LEU2-CEN3 intervals increases approximately 1.5- and fourfold, respectively, when CEN3 is repositioned at HIS4. The centromere-distal HIS4-LEU2 region experiences a three- to fivefold decrease in the frequency of meiotic exchange when CEN3 is repositioned at HIS4. The inhibition of meiotic crossing over is conferred by a 627-base-pair fragment of CEN3 DNA and is not dependent on the orientation of CEN3 relative to the rest of chromosome III.
50
Gill, Arvind, Michelle Jamnongjit, and Stephen R. Hammes. "Androgens Promote Maturation and Signaling in Mouse Oocytes Independent of Transcription: A Release of Inhibition Model for Mammalian Oocyte Meiosis." Molecular Endocrinology 18, no. 1 (January 1, 2004): 97–104. http://dx.doi.org/10.1210/me.2003-0326.
Full textAbstract:
Abstract Normal fertility in females depends upon precise regulation of oocyte meiosis. Oocytes are arrested in prophase I of meiosis until just before ovulation, when meiosis, or maturation, is triggered to resume. Whereas sex steroids appear to promote maturation in fish and amphibians, the factors regulating mammalian oocyte maturation have remained obscure. We show here that, similar to lower vertebrates, steroids may play a role in promoting the release of meiotic inhibition in mammals. Specifically, testosterone induced maturation of mouse oocytes arrested in meiosis, as well as activation of MAPK and cyclin-dependent kinase 1 signaling. These responses appeared to be transcription independent and might involve signaling through classical androgen receptors expressed in the oocytes. Our results are the first to show that sex steroids can modulate meiosis in mammalian oocytes and suggest a model whereby dominant ovarian follicles in mammals may produce sufficient androgen and/or other steroids to overcome constitutive inhibitory signals and allow oocyte maturation and subsequent ovulation to occur.