scholarly journals Mouse Emi2 is required to enter meiosis II by reestablishing cyclin B1 during interkinesis

2006 ◽  
Vol 174 (6) ◽  
pp. 791-801 ◽  
Author(s):  
Suzanne Madgwick ◽  
David V. Hansen ◽  
Mark Levasseur ◽  
Peter K. Jackson ◽  
Keith T. Jones
Keyword(s):  
Fluorescent Protein ◽  
Polar Body ◽  
Cyclin B1 ◽  
Anaphase Promoting Complex ◽  
Morpholino Knockdown ◽  
Short Time ◽  
Mitotic Inhibitor ◽  
Antisense Morpholino ◽  
Meiosis I

During interkinesis, a metaphase II (MetII) spindle is built immediately after the completion of meiosis I. Oocytes then remain MetII arrested until fertilization. In mouse, we find that early mitotic inhibitor 2 (Emi2), which is an anaphase-promoting complex inhibitor, is involved in both the establishment and the maintenance of MetII arrest. In MetII oocytes, Emi2 needs to be degraded for oocytes to exit meiosis, and such degradation, as visualized by fluorescent protein tagging, occurred tens of minutes ahead of cyclin B1. Emi2 antisense morpholino knockdown during oocyte maturation did not affect polar body (PB) extrusion. However, in interkinesis the central spindle microtubules from meiosis I persisted for a short time, and a MetII spindle failed to assemble. The chromatin in the oocyte quickly decondensed and a nucleus formed. All of these effects were caused by the essential role of Emi2 in stabilizing cyclin B1 after the first PB extrusion because in Emi2 knockdown oocytes a MetII spindle was recovered by Emi2 rescue or by expression of nondegradable cyclin B1 after meiosis I.

scholarly journals Mad2 is required for inhibiting securin and cyclin B degradation following spindle depolymerisation in meiosis I mouse oocytes

Reproduction ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 829-843 ◽  
Author(s):  
Hayden A Homer ◽  
Alex McDougall ◽  
Mark Levasseur ◽  
Alison P Murdoch ◽  
Mary Herbert
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Polar Body ◽  
Cyclin B ◽  
Mutant Form ◽  
Anaphase Promoting Complex ◽  
Mouse Oocytes ◽  
First Polar Body ◽  
Polar Body Extrusion ◽  
Meiosis I

Mad2 is a pivotal component of the spindle assembly checkpoint (SAC) which inhibits anaphase promoting complex/cyclo-some (APC/C) activity by sequestering Cdc20 thereby regulating the destruction of securin and cyclin B. During mitosis, spindle depolymerisation induces a robust Mad2-dependent arrest due to inhibition of securin and cyclin B destruction. In contrast to mitosis, the molecular details underpinning the meiosis I arrest experienced by mouse oocytes exposed to spindle depolymerisation remain incompletely characterised. Notably, the role of Mad2 and the fate of the anaphase-marker, securin, are unexplored. As shown previously, we find that spindle depolymerisation by nocodazole inhibits first polar body extrusion (PBE) and stabilises cyclin B and cyclin-dependent kinase 1 activity in mouse oocytes. Here we show that stabilisation of cyclin B in nocodazole can be sustained for several hours and is associated with stabilisation of securin. These effects are SAC-mediated as, in oocytes depleted of the majority of Mad2 by morpholino antisense, securin and cyclin B are destabilised and 15% of oocytes undergo PBE. This reflects premature APC/C activation as a mutant form of cyclin B lacking its APC/C degradation signal is stable in Mad2-depleted oocytes. Moreover, homologues do not disjoin during the prolonged meiosis I arrest (> 18 h) induced by nocodaozole indicating that a non-cleavage mechanism is insufficient on its own for resolution of arm cohesion in mammalian oocytes. In conclusion, when all kinetochores lack attachment and tension, mouse oocytes mount a robust Mad2-dependent meiosis I arrest which inhibits the destruction of securin and cyclin B.

scholarly journals Tdrd3 regulates the progression of meiosis II through translational control of Emi2 mRNA in mouse oocytes

2021 ◽  
Author(s):  
Natsumi Takei ◽  
Keisuke Sato ◽  
Yuki Takada ◽  
Rajan Iyyappan ◽  
Andrej Susor ◽  
...  
Keyword(s):  
Translational Control ◽  
Cyclin B1 ◽  
Anaphase Promoting Complex ◽  
Spindle Formation ◽  
Rna Granules ◽  
Mouse Oocytes ◽  
Oocyte Meiosis ◽  
Tudor Domain ◽  
Mitotic Inhibitor ◽  
Meiosis I

ABSTRACTAfter completion of meiosis I, the oocyte immediately enters meiosis II and forms a metaphase II (MII) spindle without an interphase, which is fundamental for generating a haploid gamete. Here, we identify tudor domain-containing protein 3 (Tdrd3) as a novel regulator of oocyte meiosis. Although early mitotic inhibitor 2 (Emi2) protein has been shown to ensure the meiosis I to II transition and the subsequent MII spindle formation by inhibiting the anaphase-promoting complex/cyclosome (APC/C), how it accumulates after meiosis I has remained unresolved. We isolated Tdrd3 as a protein directly binding to Emi2 mRNA. In GV-stage mouse oocytes, Emi2 mRNA assembled into RNA granules containing Tdrd3, while cyclin B1 mRNA, which was translated in early meiosis I, formed different granules. Knockdown of Tdrd3 attenuated Emi2 synthesis in meiosis II without affecting cyclin B1 synthesis in meiosis I. Moreover, Tdrd3-deficient oocytes entered interphase and failed to form an MII spindle after completion of meiosis I. Taken together, our results indicate the importance of Tdrd3-mediated translational control of Emi2 mRNA, which promotes Emi2 synthesis in meiosis II, for the progression of meiosis.

scholarly journals Dual-mode regulation of the APC/C by CDK1 and MAPK controls meiosis I progression and fidelity

2014 ◽  
Vol 204 (6) ◽  
pp. 891-900 ◽  
Author(s):  
Ibtissem Nabti ◽  
Petros Marangos ◽  
Jenny Bormann ◽  
Nobuaki R. Kudo ◽  
John Carroll
Keyword(s):  
Protein Kinase ◽  
Spindle Assembly Checkpoint ◽  
Mitogen Activated Protein Kinase ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Female Meiosis ◽  
Dual Mode ◽  
Mitogen Activated Protein ◽  
Meiosis I

Female meiosis is driven by the activities of two major kinases, cyclin-dependent kinase 1 (Cdk1) and mitogen-activated protein kinase (MAPK). To date, the role of MAPK in control of meiosis is thought to be restricted to maintaining metaphase II arrest through stabilizing Cdk1 activity. In this paper, we find that MAPK and Cdk1 play compensatory roles to suppress the anaphase-promoting complex/cyclosome (APC/C) activity early in prometaphase, thereby allowing accumulation of APC/C substrates essential for meiosis I. Furthermore, inhibition of MAPK around the onset of APC/C activity at the transition from meiosis I to meiosis II led to accelerated completion of meiosis I and an increase in aneuploidy at metaphase II. These effects appear to be mediated via a Cdk1/MAPK-dependent stabilization of the spindle assembly checkpoint, which when inhibited leads to increased APC/C activity. These findings demonstrate new roles for MAPK in the regulation of meiosis in mammalian oocytes.

scholarly journals Loss of Cdc20 Causes a Securin-Dependent Metaphase Arrest in Two-Cell Mouse Embryos

2007 ◽  
Vol 27 (9) ◽  
pp. 3481-3488 ◽  
Author(s):  
Min Li ◽  
J. Philippe York ◽  
Pumin Zhang
Keyword(s):  
Ubiquitin Ligase ◽  
Cyclin B1 ◽  
Mitotic Exit ◽  
Adapter Proteins ◽  
Anaphase Promoting Complex ◽  
Metaphase Arrest ◽  
Cell Stage ◽  
Gene Trapping ◽  
Protein Substrates

ABSTRACT The anaphase-promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase mediating targeted proteolysis through ubiquitination of protein substrates to control the progression of mitosis. The APC/C recognizes its substrates through two adapter proteins, Cdc20 and Cdh1, which contain similar C-terminal domains composed of seven WD-40 repeats believed to be involved in interacting with their substrates. During the transition from metaphase to anaphase, APC/C-Cdc20 mediates the ubiquitination of securin and cyclin B1, allowing the activation of separase and the onset of anaphase and mitotic exit. APC/C-Cdc20 and APC/C-Cdh1 have overlapping substrates. It is unclear whether they are redundant for mitosis. Using a gene-trapping approach, we have obtained mice which lack Cdc20 function. These mice show failed embryogenesis. The embryos were arrested in metaphase at the two-cell stage with high levels of cyclin B1, indicating an essential role of Cdc20 in mitosis that is not redundant with that of Cdh1. Interestingly, Cdc20 and securin double mutant embryos could not maintain the metaphase arrest, suggesting a role of securin in preventing mitotic exit.

scholarly journals The dynamics of cyclin B1 distribution during meiosis I in mouse oocytes

Reproduction ◽  
2004 ◽  
Vol 128 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Petros Marangos ◽  
John Carroll
Keyword(s):  
Fluorescent Protein ◽  
Germinal Vesicle ◽  
Cyclin B1 ◽  
Nuclear Accumulation ◽  
Leptomycin B ◽  
Germinal Vesicle Breakdown ◽  
Mouse Oocytes ◽  
Living Mouse ◽  
Green Fluorescent ◽  
Meiosis I

Cdk1-cyclin B1 kinase activity drives oocytes through meiotic maturation. It is regulated by the phosphorylation status of cdk1 and by its spatial organisation. Here we used a cyclin B1-green fluorescent protein (GFP) fusion protein to examine the dynamics of cdk1-cyclin B1 distribution during meiosis I (MI) in living mouse oocytes. Microinjection of cyclin B1-GFP accelerated germinal vesicle breakdown (GVBD) and, as previously described, overrides cAMP-mediated meiotic arrest. GVBD was pre-empted by a translocation of cyclin B1-GFP from the cytoplasm to the germinal vesicle (GV). After nuclear accumulation, cyclin B1-GFP localised to the chromatin. The localisation of cyclin B1-GFP is governed by nuclear import and export. In GV intact oocytes, cyclin export was demonstrated by showing that cyclin B1-GFP injected into the GV is exported to the cytoplasm while a similar size dextran is retained. Import was revealed by the finding that cyclin B1-GFP accumulated in the GV when export was inhibited using leptomycin B. These studies show that GVBD in mouse oocytes is sensitive to cyclin B1 abundance and that the changes in distribution of cyclin B1 contribute to progression through MI.

scholarly journals Mammalian egg activation: from Ca2+ spiking to cell cycle progression

Reproduction ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 813-823 ◽  
Author(s):  
Keith T Jones
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Polar Body ◽  
Signal Transduction Pathway ◽  
Cyclin B1 ◽  
Egg Activation ◽  
Anaphase Promoting Complex ◽  
Sister Chromatids ◽  
Dependent Protein ◽  
Second Polar Body

Mammalian eggs arrest at metaphase of the second meiotic division (MetII). Sperm break this arrest by inducing a series of Ca2+spikes that last for several hours. During this time cell cycle resumption is induced, sister chromatids undergo anaphase and the second polar body is extruded. This is followed by decondensation of the chromatin and the formation of pronuclei. Ca2+spiking is both the necessary and solely sufficient sperm signal to induce full egg activation. How MetII arrest is established, how the Ca2+spiking is induced and how the signal is transduced into cell cycle resumption are the topics of this review. Although the roles of most components of the signal transduction pathway remain to be fully investigated, here I present a model in which a sperm-specific phospholipase C (PLCζ) generates Ca2+spikes to activate calmodulin-dependent protein kinase II and so switch on the Anaphase-Promoting Complex/Cyclosome (APC/C). APC/C activation leads to securin and cyclin B1 degradation and in so doing allows sister chromatids to be segregated and to decondense.

scholarly journals The Anaphase Promoting Complex/Cyclosome Subunit 11 and Its Role in Organ Size and Plant Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Rodrigo Porto Schwedersky ◽  
Marina de Lyra Soriano Saleme ◽  
Ingrid Andrade Rocha ◽  
Patricia da Fonseca Montessoro ◽  
Adriana Silva Hemerly ◽  
...  
Keyword(s):  
Plant Development ◽  
Fluorescent Protein ◽  
Cortical Cell ◽  
Quiescent Center ◽  
Anaphase Promoting Complex ◽  
Catalytic Subunits ◽  
Fluorescent Marker ◽  
Green Fluorescent ◽  
Mutant Lines

The anaphase promoting complex/cyclosome (APC/C), a member of the E3 ubiquitin ligase family, plays an important role in recognizing the substrates to be ubiquitylated. Progression of anaphase, and therefore, of the cell cycle, is coordinated through cyclin degradation cycles dependent on proteolysis triggered by APC/C. The APC/C activity depends on the formation of a pocket comprising the catalytic subunits, APC2, APC11, and APC10. Among these, the role of APC11 outside the cell division cycle is poorly understood. Therefore, the goal of this work was to analyze the function of APC11 during plant development by characterizing apc11 knock-down mutant lines. Accordingly, we observed decreased apc11 expression in the mutant lines, followed by a reduction in meristem root size based on the cortical cell length, and an overall size diminishment throughout the development. Additionally, crosses of apc11-1 and amiR-apc11 with plants carrying a WUSCHEL-RELATED HOMEOBOX5 (WOX5) fluorescent marker showed a weakening of the green fluorescent protein-positive cells in the Quiescent Center. Moreover, plants with apc11-1 show a decreased leaf area, together with a decrease in the cell area when the shoot development was observed by kinematics analysis. Finally, we observed a decreased APC/C activity in the root and shoot meristems in crosses of pCYCB1;1:D-box-GUS with apc11-1 plants. Our results indicate that APC11 is important in the early stages of development, mediating meristematic architecture through APC/C activity affecting the overall plant growth.

scholarly journals Phosphorylation of the Anaphase Promoting Complex activator CDH1/FZR regulates the transition from Meiosis I to Meiosis II in mouse male germ cell

2020 ◽  
Author(s):  
Nobuhiro Tanno ◽  
Shinji Kuninaka ◽  
Sayoko Fujimura ◽  
Kaho Okamura ◽  
Kazumasa Takemoto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Germ Cells ◽  
Critical Role ◽  
Biological Significance ◽  
Mitotic Cell ◽  
Anaphase Promoting Complex ◽  
Meiosis I

SummaryCDH1/FZR is an activator of Anaphase promoting complex/Cyclosome (APC/C), best known for its role as E3 ubiquitin ligase that drives the cell cycle. APC/C activity is regulated by CDK-mediated phosphorylation of CDH1 during mitotic cell cycle. Although the critical role of CDH1 phosphorylation has been shown mainly in yeast and in vitro cell culture studies, its biological significance in mammalian tissues in vivo remained elusive. Here, we examined the in vivo role of CDH1 phosphorylation using a mouse model, in which non-phosphorylatable substitutions were introduced in the putative CDK-phosphorylation sites of CDH1. Although ablation of CDH1 phosphorylation did not show substantial consequences in mouse somatic tissues, it led to severe testicular defects resulting in male infertility. In the absence of CDH1 phosphorylation, male juvenile germ cells entered meiosis normally but skipped meiosis II producing diploid spermatid-like cells. In aged testis, male germ cells were overall abolished, showing Sertoli cell-only phenotype. The present study demonstrated that phosphorylation of CDH1 is required for temporal regulation of APC/C activity at the transition from meiosis I to meiosis II, and for spermatoginial stem cell maintenance, which raised an insight into the sexual dimorphism of CDH1-regulation in germ cells.

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