Changes in Cyclin B during Oocyte Maturation and Early Embryonic Cell Cycle in the Newt,Cynops pyrrhogaster: Requirement of Germinal Vesicle for MPF Activation

The control of the cell cycle is dependent on the ability to synthesize and degrade proteins called cyclins. When antisense oligonucleotides are used to deplete Xenopus embryos of mRNA encoding cyclin B protein, embryonic cleavage is inhibited. Surprisingly, after missing several rounds of cleavage, the cell cycle and cell division resumes. These studies indicate that the early embryonic cell cycle can proceed with undetectable levels of cyclin B encoding mRNA. In contrast, other events of normal development, including the activation of embryonic transcription and gastrulation, are inhibited.

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Centrosome changes during meiosis in horse oocytes and first embryonic cell cycle organization following parthenogenesis, fertilization and nuclear transfer

Reproduction ◽

10.1530/rep.1.00795 ◽

2006 ◽

Vol 131 (4) ◽

pp. 661-667 ◽

Cited By ~ 5

Author(s):

Xihe Li ◽

Y Qin ◽

Sandra Wilsher ◽

W R Allen

Keyword(s):

Cell Cycle ◽

Nuclear Transfer ◽

Germinal Vesicle ◽

Donor Cell ◽

Embryonic Cell ◽

Immunofluorescent Staining ◽

Sperm Chromatin ◽

Germinal Vesicle Breakdown ◽

Embryonic Cell Cycle

Various types of cell cycle organization occur in mammals. In this study, centrosome changes during meiosis in horse oocytes, and first cell cycle organization following fertilization, parthenogenesis and nuclear transfer, were monitored. Cumulus oocyte complexes harvested from horse ovaries obtained from slaughtered mares were cultured in vitro. Meiotic oocytes of germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I and II (MI and MII) stages were selected at various set times during in vitro maturation. Embryos at the first cell cycle stage were generated by subjecting MII stage oocytes to fertilization by intracytoplasmic sperm injection (ICSI), parthenogenetic treatment or nuclear transfer. Centrosome changes during meiosis and the first cell cycle organization were detected by indirect immunofluorescent staining, using a mouse anti-α-tubulin antibody for microtubules and a rabbit anti-γ-tubulin antibody for centrosomes. These examinations showed that the centrosomes of the horse oocyte reorganize themselves from the beginning of GV stage to leave only PCM of γ-tubulin surrounding both poles of the MI and MII stage spindles. These MII oocytes can organize the separation of metaphase chromosomes during the first embryonic cell cycle by parthenogenetic treatment. When the MII oocytes were subjected to ICSI or nuclear transfer, one or two red-stained centrosomes of γ-tubulin were introduced by the fertilising spermatozoon or the donor cell which associated with the sperm chromatin in the fertilized embryos and with the donor cell chromatin and microtubules in the cloned embryos. This finding suggests that centrosomes are not an essential component in the formation of the metaphase spindle during meiotic maturation of horse oocytes, but they can be introduced from the spermatozoon or donor cell and are necessary for the organization of normal embryonic development.

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Modeling the role for nuclear import dynamics in the early embryonic cell cycle

Biophysical Journal ◽

10.1016/j.bpj.2021.05.005 ◽

2021 ◽

Author(s):

Yuki Shindo ◽

Amanda A. Amodeo

Keyword(s):

Cell Cycle ◽

Nuclear Import ◽

Embryonic Cell ◽

Embryonic Cell Cycle

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Association of cyclin-bound p34cdc2 with subcellular structures in xenopus eggs

Journal of Cell Science ◽

10.1242/jcs.102.2.285 ◽

1992 ◽

Vol 102 (2) ◽

pp. 285-297 ◽

Cited By ~ 1

Author(s):

D. Leiss ◽

M.A. Felix ◽

E. Karsenti

Keyword(s):

Cell Cycle ◽

Ribosomal Proteins ◽

Cell Cycle Progression ◽

Gradient Centrifugation ◽

Preliminary Evidence ◽

Embryonic Cell ◽

Cytoskeletal Proteins ◽

Cyclin B ◽

Post Translational Modifications ◽

Egg Extracts

Cell cycle progression is controlled by changes in kinase activity of homologs of the fission yeast protein p34cdc2. The p34cdc2 kinase is activated by its association with a cyclin subunit, followed by post-translational modifications. Here, we show that in Xenopus eggs stimulated to enter the early embryonic cell cycle by an electric shock, part of the p34cdc2 becomes associated with subcellular fractions as the eggs progress towards mitosis. This occurs as a result of cyclin accumulation because most of the B-type cyclins and some of the A-type cyclins are found in the particulate fraction. Moreover, as soon as cyclins are degraded, p34cdc2 is released in the soluble fraction. The p34cdc2-cyclin complex can be solubilised by 80 mM beta-glycerophosphate (in the standard MPF extraction buffer) or by high salt concentrations. The post-translational modifications leading to cdc2 kinase activation by cyclin occur in the insoluble form. Following fractionation of egg extracts by sucrose gradient centrifugation, the p34cdc2-cyclin B complex is found in several fractions, but especially in two discrete peaks. We present evidence that in the slow-sedimenting peak the p34cdc2-cyclin B complex is associated with the 60 S subunit of monoribosomes. It could be targeted in this fashion to substrates such as ribosomal proteins and maybe to cytoskeletal proteins, since ribosomes bind to microtubules and are present in the spindle. The p34cdc2-cyclin B complex is also found in a faster-migrating fraction containing various membranous structures, including Golgi stacks. Therefore, as observed by immunofluorescence in other systems, it seems that cyclin subunits target p34cdc2 to specific cellular sites and this is certainly important for its function. In addition, we present preliminary evidence suggesting that some component present in the ribosome-containing fraction is required for activation of the p34cdc2-cyclin B complex.

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Distribution of the Germinal Vesicle Material during Progesterone-Induced Oocyte Maturation in Xenopus and in Cynops. (germinal vesicle material/oocyte maturation/Xenopus laevis/Cynops pyrrhogaster)

Development Growth & Differentiation ◽

10.1111/j.1440-169x.1984.00157.x ◽

1984 ◽

Vol 26 (2) ◽

pp. 157-165 ◽

Cited By ~ 16

Author(s):

HIROSHI IMOH ◽

YASUYO MIYAZAKI

Keyword(s):

Xenopus Laevis ◽

Oocyte Maturation ◽

Germinal Vesicle ◽

Cynops Pyrrhogaster

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Accumulation and dynamics of proteins of the MCM family during mouse oogenesis and the first embryonic cell cycle

The International Journal of Developmental Biology ◽

10.1387/ijdb.062239ls ◽

2007 ◽

Vol 51 (4) ◽

pp. 283-295 ◽

Cited By ~ 13

Author(s):

Lukasz Swiech ◽

Katarzyna Kisiel ◽

Renata Czolowska ◽

Maciej Zientarski ◽

Ewa Borsuk

Keyword(s):

Cell Cycle ◽

Embryonic Cell ◽

Embryonic Cell Cycle

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c-mos and cdc2 Cooperate in the Translational Activation of Fibroblast Growth Factor Receptor-1 duringXenopus Oocyte Maturation

Molecular Biology of the Cell ◽

10.1091/mbc.10.11.3567 ◽

1999 ◽

Vol 10 (11) ◽

pp. 3567-3581 ◽

Cited By ~ 5

Author(s):

Patricia A. Culp ◽

Thomas J. Musci

Keyword(s):

Cell Cycle ◽

Oocyte Maturation ◽

Growth Factor Receptor ◽

Cyclin B ◽

Meiotic Cell ◽

Fgf Receptor ◽

Maternal Mrna ◽

Mapk Activity ◽

Cellular Events ◽

Translational Activation

During oocyte maturation in Xenopus, previously quiescent maternal mRNAs are translationally activated at specific times. We hypothesized that the translational recruitment of individual messages is triggered by particular cellular events and investigated the potential for known effectors of the meiotic cell cycle to activate the translation of the FGF receptor-1 (XFGFR) maternal mRNA. We found that both c-mos and cdc2 activate the translation of XFGFR. However, although oocytes matured by injection of recombinant cdc2/cyclin B translate normal levels of XFGFR protein, c-mos depletion reduces the level of XFGFR protein induced by cdc2/cyclin B injection. In oocytes blocked for cdc2 activity, injection of mos RNA induced low levels of XFGFR protein, independent of MAPK activity. Through the use of injected reporter RNAs, we show that the XFGFR 3′ untranslated region inhibitory element is completely derepressed by cdc2 alone. In addition, we identified a new inhibitory element through which both mos and cdc2 activate translation. We found that cdc2 derepresses translation in the absence of polyadenylation, whereas mos requires poly(A) extension to activate XFGFR translation. Our results demonstrate that mos and cdc2, in addition to functioning as key regulators of the meiotic cell cycle, cooperate in the translational activation of a specific maternal mRNA during oocyte maturation.

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A Role for Cdk2 Kinase in Negatively Regulating DNA Replication during S Phase of the Cell Cycle

The Journal of Cell Biology ◽

10.1083/jcb.137.1.183 ◽

1997 ◽

Vol 137 (1) ◽

pp. 183-192 ◽

Cited By ~ 98

Author(s):

Xuequn Helen Hua ◽

Hong Yan ◽

John Newport

Keyword(s):

Cell Cycle ◽

Dna Replication ◽

Cyclin E ◽

Embryonic Cell ◽

S Phase ◽

Negative Regulation ◽

Sperm Chromatin ◽

High Concentration ◽

Low Concentrations ◽

Embryonic Cell Cycle

Using cell-free extracts made from Xenopus eggs, we show that cdk2-cyclin E and A kinases play an important role in negatively regulating DNA replication. Specifically, we demonstrate that the cdk2 kinase concentration surrounding chromatin in extracts increases 200-fold once the chromatin is assembled into nuclei. Further, we find that if the cdk2–cyclin E or A concentration in egg cytosol is increased 16-fold before the addition of sperm chromatin, the chromatin fails to initiate DNA replication once assembled into nuclei. This demonstrates that cdk2–cyclin E or A can negatively regulate DNA replication. With respect to how this negative regulation occurs, we show that high levels of cdk2–cyclin E do not block the association of the protein complex ORC with sperm chromatin but do prevent association of MCM3, a protein essential for replication. Importantly, we find that MCM3 that is prebound to chromatin does not dissociate when cdk2– cyclin E levels are increased. Taken together our results strongly suggest that during the embryonic cell cycle, the low concentrations of cdk2–cyclin E present in the cytosol after mitosis and before nuclear formation allow proteins essential for potentiating DNA replication to bind to chromatin, and that the high concentration of cdk2–cyclin E within nuclei prevents MCM from reassociating with chromatin after replication. This situation could serve, in part, to limit DNA replication to a single round per cell cycle.

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The Design Space of the Embryonic Cell Cycle Oscillator

Biophysical Journal ◽

10.1016/j.bpj.2017.06.045 ◽

2017 ◽

Vol 113 (3) ◽

pp. 743-752 ◽

Cited By ~ 2

Author(s):

Henry H. Mattingly ◽

Moshe Sheintuch ◽

Stanislav Y. Shvartsman

Keyword(s):

Cell Cycle ◽

Design Space ◽

Embryonic Cell ◽

Embryonic Cell Cycle

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