scholarly journals Cytoplasmic polyadenylation controls cdc25B mRNA translation in rat oocytes resuming meiosis

Reproduction ◽  
2006 ◽  
Vol 132 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Eran Gershon ◽  
Dalia Galiani ◽  
Nava Dekel
Keyword(s):  
Neutralizing Antibodies ◽  
Germinal Vesicle ◽  
Mrna Translation ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Germinal Vesicle Breakdown ◽  
Cytoplasmic Polyadenylation ◽  
Dual Specificity ◽  
M Phase ◽  
Mrna Polyadenylation

Resumption of meiosis in oocytes represents the entry into M-phase of the cell cycle and is regulated by the maturation-promoting factor (MPF). Activation of MPF is catalyzed by the dual specificity phosphatase, cdc25. In mammals, cdc25 is represented by a multigene family consisting of three isoforms: A, B and C. A recent report that female mice lacking cdc25B exhibit impaired fertility suggests a role for this isoform in regulating the G2- to M-transition in mammalian oocytes. Supporting the above-mentioned observation, we demonstrate herein that microinjection of neutralizing antibodies against cdc25B interfered with the ability of rat oocytes to undergo germinal vesicle breakdown (GVB). We also show accumulation of cdc25B in GVB oocytes and a transient reduction in its amount at metaphase I of meiosis. The accumulation of cdc25B was associated with its mRNA cytoplasmatic polyadenylation and was prevented by the protein synthesis inhibitor cyclohexamide as well as by the polyadenylation inhibitor cordycepin. Immunofluorescence staining revealed translocation of cdc25B to the metaphase II spindle apparatus. Taken together, our findings provide evidence that cdc25B is involved in resumption of meiosis in rat oocytes. We further demonstrate for the first time, a periodic accumulation of cdc25B throughout meiosis that is translationally regulated and involves cdc25B mRNA polyadenylation.

Synchronization of porcine oocyte meiosis using cycloheximide and its application to the study of regulation by cumulus cells

2002 ◽  
Vol 14 (7) ◽  
pp. 433 ◽  
Author(s):  
J. Ye ◽  
A. P. F. Flint ◽  
K. H. S. Campbell ◽  
M. R. Luck
Keyword(s):  
Germinal Vesicle ◽  
Cumulus Cells ◽  
Protein Synthesis Inhibitor ◽  
Dependent Manner ◽  
Synthesis Inhibitor ◽  
Germinal Vesicle Breakdown ◽  
Nuclear Maturation ◽  
Meiotic Progression ◽  
Conventional Culture ◽  
Oocyte Meiosis

This paper describes the use of the protein synthesis inhibitor cycloheximide (CHX) to synchronize nuclear progression during meiotic maturation in porcine oocytes, and also the time-dependence of nuclear maturation on exposure of the oocyte to cumulus cells. Prior to culture, the majority of oocytes were at the germinal vesicle (GV) stage (95–100%), but distributed from GVI to GVIV (GVI 56.1 ± 9.1%, GVII 15.3 ± 1.4%, GVIII 21.5 ± 7.1%, GVIV 7.1 ± 3.5%). During culture of cumulus-enclosed oocytes (COCs) from 12 h to 48 h in a conventional culture system, all meiotic stages were represented at any time point examined, with 63.6 ± 4.2% of oocytes maturing to metaphase II (MII). Cycloheximide blocked the progression of nuclear development in a dose-dependent manner. Treatment for 12 h with CHX at 1–25 μg mL–1 resulted in 95–100% oocytes being arrested and synchronized at GVII. With >5 μg mL–1 CHX, all oocytes were arrested before germinal vesicle breakdown (GVBD) (mostly at GVIII) by 24 h. A 12 h preincubation with 5 μg mL–1 CHX followed by 24 h of further culture without CHX resulted in >80% of oocytes maturing to MII. The profile of nuclear progression during maturation revealed discrete peaks of occurrence of different meiotic stages, with GVBD at 6–12 h, metaphase I (MI) at 10–18�h and anaphase I/telophase I at 16–20 h. After 12 h preincubation with 5 μg mL–1 CHX, denuded oocytes (DOs) matured to MI as COCs. However, DOs matured to MII as normal when denuded at MI. In conclusion, CHX not only efficiently blocks and synchronizes the meiotic progression of porcine oocytes at a specific GV stage, but it also effectively synchronizes subsequent meiotic progression to MII, resulting in discrete peaks of occurrence of different meiotic stages. Using this technique, the study showed that cumulus cells are essential for oocytes to mature from MI to MII but exposure to cumulus cells must occur before MI.

scholarly journals A nuclear factor required for specific translation of cyclin B may control the timing of first meiotic cleavage in starfish oocytes.

1993 ◽  
Vol 4 (12) ◽  
pp. 1295-1306 ◽  
Author(s):  
S Galas ◽  
H Barakat ◽  
M Dorée ◽  
A Picard
Keyword(s):  
Protein Synthesis ◽  
Metaphase Plate ◽  
Germinal Vesicle ◽  
Cyclin B ◽  
Protein Synthesis Inhibitor ◽  
Nuclear Factor ◽  
Synthesis Inhibitor ◽  
Cdc2 Kinase ◽  
Hormonal Stimulation ◽  
Germinal Vesicle Breakdown

In most animals, the rate of cyclin B synthesis increases after nuclear envelope breakdown during the first meiotic cell cycle. We have found that cyclin B-cdc2 kinase activity drops earlier in emetine-treated than in control starfish oocytes, although the protein synthesis inhibitor does not activate the cyclin degradation pathway prematurely. Moreover, protein synthesis is required to prevent meiotic cleavage to occur prematurely, sometimes before chromosomes have segregated on the metaphase plate. In normal conditions, increased synthesis of cyclin B after germinal vesicle breakdown (GVBD) balances cyclin degradation and increases the time required for cyclin B-cdc2 kinase to drop below the level that inhibits cleavage. Taken together, these results point to cyclin B as a possible candidate that could explain the need for increased protein synthesis during meiosis I. Although direct experimental evidence was not provided in the present work, cyclin B synthesis after GVBD may be important for correct segregation of homologous chromosomes at the end of first meiotic metaphase, as shown by a variety of cytological disorders that accompany premature cleavage. Although the overall stimulation of protein synthesis because of cdc2 kinase activation is still observed in oocytes from which the germinal vesicle has been removed before hormonal stimulation, the main increase of cyclin B synthesis normally observed after germinal vesicle breakdown is suppressed. The nuclear factor required for specific translation of cyclin B after GVBD is not cyclin B mRNA, as shown by using a highly sensitive reverse transcription followed by polymerase chain reaction procedure that failed to detect any cyclin B mRNA in isolated germinal vesicles.

scholarly journals Cyclin B2 is required for progression through meiosis in mouse oocytes

2018 ◽  
Author(s):  
Enrico Maria Daldello ◽  
Xuan G. Luong ◽  
Cai-Rong Yang ◽  
Jonathan Kuhn ◽  
Marco Conti
Keyword(s):  
Cell Cycle Progression ◽  
Germinal Vesicle ◽  
Mrna Translation ◽  
Developmental Competence ◽  
Germinal Vesicle Breakdown ◽  
Cycle Progression ◽  
Oocyte Developmental Competence ◽  
M Phase ◽  
Mitosis And Meiosis

ABSTRACTCyclins associate with CDK1 to generate the M-phase-promoting factor (MPF) essential for progression through mitosis and meiosis. Previous studies concluded that CCNB2 is dispensable for cell cycle progression. Given our findings of high translation rates ofCcnB2mRNA in prophase-arrested oocytes, we have reevaluated its role during meiosis.CcnB2−/−oocytes undergo delayed germinal vesicle breakdown followed by a defective M-phase due to reduced pre-MPF activity. This disrupted maturation is associated with compromisedCcnB1andMosmRNA translation and delayed spindle assembly. Given these defects, a significant population of oocytes fail to complete meiosis I because SAC remains activated and APC function is inhibited.In vivo, CCNB2 depletion leads to decreased oocyte developmental competence, compromised fecundity, and premature ovarian failure. These findings demonstrate that CCNB2 is required to assemble sufficient pre-MPF for timely meiosis reentry and progression. Although endogenous cyclins cannot compensate, overexpression of CCNB1 rescues the meiotic phenotypes, demonstrating similar molecular properties but divergent modes of regulation of these cyclins.

Meiosis reinitiation in the mollusc Patella vulgata. Regulation of MPF, CSF and chromosome condensation activity by intracellular pH, protein synthesis and phosphorylation

Development ◽  
1988 ◽  
Vol 102 (3) ◽  
pp. 505-516
Author(s):  
I. Neant ◽  
P. Guerrier
Keyword(s):  
Protein Synthesis ◽  
Protein Phosphorylation ◽  
Germinal Vesicle ◽  
Chromosome Condensation ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Patella Vulgata ◽  
M Phase ◽  
Condensation Activity ◽  
Cytostatic Factor

The dependency of some key events of the cell cycle upon pH, phosphorylation and protein synthesis was investigated during meiosis reinitiation of Patella vulgata oocytes stimulated by ammonia. In this report, we show, through heterologous microinjection experiments, that a stable maturation promoting factor (MPF) is actually produced under these conditions. This factor, which may be amplified in recipient germinal vesicle (GV)-blocked oocytes of the starfish Asterias rubens, but not of Patella, remains present in the metaphase-1-blocked oocytes for at least 2á5h. Using effective concentrations of the protein synthesis inhibitor emetine, we further demonstrate that the appearance of this factor does not depend on newly made proteins, whereas the maintenance of metaphase-1 conditions and chromosome condensation activity (CCA), which has been related to the simultaneous presence of a cytostatic factor (CSF), requires a continuous supply of new short-lived proteins. Without this, the chromosomes decondense and the nuclear envelope reforms. Finally, we show that the entry into M-phase is accompanied by extensive protein phosphorylation, while the drug 6-dimethylaminopurine (6-DMAP), which induces protein dephosphorylation without affecting protein synthesis or phosphoprotein phosphatase activity, produces the same cytological effects as emetine. The fact that the effect of 6-DMAP, both on protein phosphorylation and chromosome structure, is perfectly reversible indicates that Patella CSF activity must also be controlled at the posttranslational level, possibly through the activation of relevant protein kinases.

scholarly journals Involvement of protein phosphatases 1 and 2A in the control of M phase-promoting factor activity in starfish.

1989 ◽  
Vol 109 (6) ◽  
pp. 3347-3354 ◽  
Author(s):  
A Picard ◽  
J P Capony ◽  
D L Brautigan ◽  
M Dorée
Keyword(s):  
Okadaic Acid ◽  
Protein Phosphatases ◽  
Germinal Vesicle ◽  
Histone H1 ◽  
Specific Inhibition ◽  
Factor Activity ◽  
Microtubule Network ◽  
Germinal Vesicle Breakdown ◽  
M Phase

Specific inhibition of types 1 and 2A protein phosphatases by microinjection of okadaic acid (OA) into starfish oocytes induced germinal vesicle breakdown and activation of M phase-promoting factor (MPF) and histone H1 kinase. The effects were evident in immature oocytes arrested at first meiotic prophase as well as in fully mature oocytes arrested at the pronucleus stage. In addition, MPF and histone H1 kinase were stabilized for several hours and protected from inactivation by inhibition of type 1 protein phosphatases with either OA or specific anti-phosphatase antibodies. Microinjection of okadaic acid was associated with unusual changes of the microtubule network, including the disappearance of spindles and extension of the cytoplasmic array of microtubules. MPF activation after OA injection was associated with dephosphorylation of phosphothreonine and phosphoserine residues in cdc2, showing that neither type 1 nor 2A protein phosphatases catalyzes these dephosphorylations. The effects of OA on MPF activation and inactivation appeared to involve the cyclin subunit. OA did not induce MPF activation in the absence of protein synthesis and it prevented degradation of cyclin. Therefore protein phosphatases types 1 and 2A appear to be involved in activation and inactivation of MPF involving mechanisms that operate after cyclin synthesis and before its degradation.

scholarly journals Cell cycle dynamics of an M-phase-specific cytoplasmic factor in Xenopus laevis oocytes and eggs.

1984 ◽  
Vol 98 (4) ◽  
pp. 1247-1255 ◽  
Author(s):  
J Gerhart ◽  
M Wu ◽  
M Kirschner
Keyword(s):  
Cell Cycle ◽  
Xenopus Laevis ◽  
Germinal Vesicle ◽  
Small Scale ◽  
Xenopus Laevis Oocytes ◽  
Germinal Vesicle Breakdown ◽  
Cytoplasmic Factor ◽  
M Phase ◽  
Cytostatic Factor ◽  
Meiotic Cycle

We have examined the regulation of maturation-promoting factor (MPF) activity in the mitotic and meiotic cell cycles of Xenopus laevis eggs and oocytes. To this end, we developed a method for the small scale extraction of eggs and oocytes and measured MPF activity in extracts by a dilution end point assay. We find that in oocytes, MPF activity appears before germinal vesicle breakdown and then disappears rapidly at the end of the first meiotic cycle. In the second meiotic cycle, MPF reappears before second metaphase, when maturation arrests. Thus, MPF cycling coincides with the abbreviated cycles of meiosis. When oocytes are induced to mature by low levels of injected MPF, cycloheximide does not prevent the appearance of MPF at high levels in the first cycle. This amplification indicates that an MPF precursor is present in the oocyte and activated by posttranslational means, triggered by the low level of injected MPF. Furthermore, MPF disappears approximately on time in such oocytes, indicating that the agent for MPF inactivation is also activated by posttranslational means. However, in the absence of protein synthesis, MPF never reappears in the second meiotic cycle. Upon fertilization or artificial activation of normal eggs, MPF disappears from the cytoplasm within 8 min. For a period thereafter, the inactivating agent remains able to destroy large amounts of MPF injected into the egg. It loses activity just as endogenous MPF appears at prophase of the first mitotic cycle. The repeated reciprocal cycling of MPF and the inactivating agent during cleavage stages is unaffected by colchicine and nocodazole and therefore does not require the effective completion of spindle formation, mitosis, or cytokinesis. However, MPF appearance is blocked by cycloheximide applied before mitosis; and MPF disappearance is blocked by cytostatic factor. In all these respects, MPF and the inactivating agent seem to be tightly linked to, and perhaps participate in, the cell cycle oscillator previously described for cleaving eggs of Xenopus laevis (Hara, K., P. Tydeman, and M. Kirschner, 1980, Proc. Natl. Acad. Sci. USA, 77:462-466).

scholarly journals p70S6K Controls Selective mRNA Translation during Oocyte Maturation and Early Embryogenesis inXenopus laevis

1999 ◽  
Vol 19 (4) ◽  
pp. 2485-2494 ◽  
Author(s):  
Markus S. Schwab ◽  
Sang H. Kim ◽  
Naohiro Terada ◽  
Catarina Edfjäll ◽  
Sara C. Kozma ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Translational Control ◽  
Mammalian Cells ◽  
Germinal Vesicle ◽  
Mrna Translation ◽  
Early Embryogenesis ◽  
Entry Site ◽  
Germinal Vesicle Breakdown ◽  
Rapamycin Treatment

ABSTRACT In mammalian cells, p70S6K plays a key role in translational control of cell proliferation in response to growth factors. Because of the reliance on translational control in early vertebrate development, we cloned a Xenopus homolog of p70S6K and investigated the activity profile of p70S6K during Xenopus oocyte maturation and early embryogenesis. p70S6K activity is high in resting oocytes and decreases to background levels upon stimulation of maturation with progesterone. During embryonic development, three peaks of activity were observed: immediately after fertilization, shortly before the midblastula transition, and during gastrulation. Rapamycin, an inhibitor of p70S6K activation, caused oocytes to undergo germinal vesicle breakdown earlier than control oocytes, and sensitivity to progesterone was increased. Injection of a rapamycin-insensitive, constitutively active mutant of p70S6K reversed the effects of rapamycin. However, increases in S6 phosphorylation were not significantly affected by rapamycin during maturation. mosmRNA, which does not contain a 5′-terminal oligopyrimidine tract (5′-TOP), was translated earlier, and a larger amount of Mos protein was produced in rapamycin-treated oocytes. In fertilized eggs rapamycin treatment increased the translation of the Cdc25A phosphatase, which lacks a 5′-TOP. Translation assays in vivo using both DNA and RNA reporter constructs with the 5′-TOP from elongation factor 2 showed decreased translational activity with rapamycin, whereas constructs without a 5′-TOP or with an internal ribosome entry site were translated more efficiently upon rapamycin treatment. These results suggest that changes in p70S6K activity during oocyte maturation and early embryogenesis selectively alter the translational capacity available for mRNAs lacking a 5′-TOP region.

scholarly journals The GTPase SPAG-1 orchestrates meiotic program by dictating meiotic resumption and cytoskeleton architecture in mouse oocytes

2016 ◽  
Vol 27 (11) ◽  
pp. 1776-1785 ◽  
Author(s):  
Chunjie Huang ◽  
Di Wu ◽  
Faheem Ahmed Khan ◽  
Xiaofei Jiao ◽  
Kaifeng Guan ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Polar Body ◽  
Germinal Vesicle ◽  
Mapk Signaling ◽  
Cortical Granule ◽  
Germinal Vesicle Breakdown ◽  
Atp Production ◽  
M Phase ◽  
Polar Body Extrusion ◽  
Actin Expression

In mammals, a finite population of oocytes is generated during embryogenesis, and proper oocyte meiotic divisions are crucial for fertility. Sperm-associated antigen 1 (SPAG-1) has been implicated in infertility and tumorigenesis; however, its relevance in cell cycle programs remains rudimentary. Here we explore a novel role of SPAG-1 during oocyte meiotic progression. SPAG-1 associated with meiotic spindles and its depletion severely compromised M-phase entry (germinal vesicle breakdown [GVBD]) and polar body extrusion. The GVBD defect observed was due to an increase in intraoocyte cAMP abundance and decrease in ATP production, as confirmed by the activation of AMP-dependent kinase (AMPK). SPAG-1 RNA interference (RNAi)–elicited defective spindle morphogenesis was evidenced by the dysfunction of γ-tubulin, which resulted from substantially reduced phosphorylation of MAPK and irregularly dispersed distribution of phospho-MAPK around spindles instead of concentration at spindle poles. Significantly, actin expression abruptly decreased and formation of cortical granule–free domains, actin caps, and contractile ring disrupted by SPAG-1 RNAi. In addition, the spindle assembly checkpoint remained functional upon SPAG-1 depletion. The findings broaden our knowledge of SPAG-1, showing that it exerts a role in oocyte meiotic execution via its involvement in AMPK and MAPK signaling pathways.

scholarly journals Aurora kinase B inhibits Aurora kinase A to control maternal mRNA translation in mouse oocytes

Development ◽  
2021 ◽  
Author(s):  
Mansour Aboelenain ◽  
Karen Schindler
Keyword(s):  
Mrna Translation ◽  
Aurora Kinase ◽  
Cytoplasmic Polyadenylation ◽  
Aurora Kinase A ◽  
Aurora Kinase B ◽  
Maternal Mrna ◽  
Kinase C ◽  
Maternal Mrnas ◽  
Mrna Polyadenylation ◽  
Kinase A

Mammalian oocytes are transcriptionally quiescent, and meiosis and early embryonic divisions rely on translation of stored maternal mRNAs. Activation of these mRNAs is mediated by polyadenylation. Cytoplasmic polyadenylation binding element 1 (CPEB1) regulates activates mRNA polyadenylation. One message is Aurora kinase C (Aurkc), encoding a protein that regulates chromosome segregation. We previously demonstrated that AURKC levels are upregulated in oocytes lacking Aurora kinase B (AURKB), and this upregulation caused increased aneuploidy rates, a role we investigate here. Using genetic and pharmacologic approaches, we found that AURKB negatively regulates CPEB1-dependent translation of many messages. To determine why translation is increased, we evaluated Aurora kinase A (AURKA), a kinase that activates CPEB1 in other organisms. We find that AURKA activity is increased in Aurkb knockout oocytes and demonstrate that this increase drives the excess translation. Importantly, removal of one copy of Aurka from the Aurkb knockout strain background, reduces aneuploidy rates. This study demonstrates that AURKA is required for CPEB1-dependent translation, and it describes a new AURKB requirement to maintain translation levels through AURKA, a function critical to generating euploid eggs.

scholarly journals Host cell factors controlling vimentin organization in the Xenopus oocyte.

1992 ◽  
Vol 119 (4) ◽  
pp. 855-866 ◽  
Author(s):  
J A Dent ◽  
R B Cary ◽  
J B Bachant ◽  
A Domingo ◽  
M W Klymkowsky
Keyword(s):  
Direct Interaction ◽  
Germinal Vesicle ◽  
Germinal Vesicle Breakdown ◽  
Head Domain ◽  
M Phase ◽  
Filament Bundles ◽  
Keratin Filament ◽  
Vimentin Filaments

To study vimentin filament organization in vivo we injected Xenopus oocytes, which have no significant vimentin system of their own, with in vitro-synthesized RNAs encoding Xenopus vimentins. Exogenous vimentins were localized primarily to the cytoplasmic surface of the nucleus and to the subplasma membrane "cortex." In the cortex of the animal hemisphere, wild-type vimentin forms punctate structures and short filaments. In contrast, long anastomosing vimentin filaments are formed in the vegetal hemisphere cortex. This asymmetry in the organization of exogenous vimentin is similar to that of the endogenous keratin system (Klymkowsky, M. W., L. A. Maynell, and A. G. Polson. 1987. Development (Camb.). 100:543-557), which suggests that the same cellular factors are responsible for both. Before germinal vesicle breakdown, in the initial stage of oocyte maturation, large vimentin and keratin filament bundles appear in the animal hemisphere. As maturation proceeds, keratin filaments fragment into soluble oligomers (Klymkowsky, M. W., L. A. Maynell, and C. Nislow. 1991. J. Cell Biol. 114:787-797), while vimentin filaments remain intact and vimentin is hyperphosphorylated. To examine the role of MPF kinase in the M-phase reorganization of vimentin we deleted the conserved proline of vimentin's single MPF-kinase site; this mutation had no apparent effect on the prophase or M-phase behavior of vimentin. In contrast, deletion of amino acids 19-68 or 18-61 of the NH2-terminal "head" domain produced proteins that formed extended filaments in the animal hemisphere of the prophase oocyte. We suggest that the animal hemisphere cortex of the prophase oocyte contains a factor that actively suppresses the formation of extended vimentin filaments through a direct interaction with vimentin's head domain. During maturation this "suppressor of extended filaments" appears to be inactivated, leading to the formation of an extended vimentin filament system.

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