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.

scholarly journals BCL-2 Is Phosphorylated and Inactivated by an ASK1/Jun N-Terminal Protein Kinase Pathway Normally Activated at G2/M

1999 ◽  
Vol 19 (12) ◽  
pp. 8469-8478 ◽  
Author(s):  
Kazuhito Yamamoto ◽  
Hidenori Ichijo ◽  
Stanley J. Korsmeyer
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Cell Cycle Progression ◽  
Peptide Mapping ◽  
Dominant Negative ◽  
Terminal Protein ◽  
Cycle Progression ◽  
M Phase ◽  
Death Signals

ABSTRACT Multiple signal transduction pathways are capable of modifying BCL-2 family members to reset susceptibility to apoptosis. We used two-dimensional peptide mapping and sequencing to identify three residues (Ser70, Ser87, and Thr69) within the unstructured loop of BCL-2 that were phosphorylated in response to microtubule-damaging agents, which also arrest cells at G2/M. Changing these sites to alanine conferred more antiapoptotic activity on BCL-2 following physiologic death signals as well as paclitaxel, indicating that phosphorylation is inactivating. An examination of cycling cells enriched by elutriation for distinct phases of the cell cycle revealed that BCL-2 was phosphorylated at the G2/M phase of the cell cycle. G2/M-phase cells proved more susceptible to death signals, and phosphorylation of BCL-2 appeared to be responsible, as a Ser70Ala substitution restored resistance to apoptosis. We noted that ASK1 and JNK1 were normally activated at G2/M phase, and JNK was capable of phosphorylating BCL-2. Expression of a series of wild-type and dominant-negative kinases indicated an ASK1/Jun N-terminal protein kinase 1 (JNK1) pathway phosphorylated BCL-2 in vivo. Moreover, the combination of dominant negative ASK1, (dnASK1), dnMKK7, and dnJNK1 inhibited paclitaxel-induced BCL-2 phosphorylation. Thus, stress response kinases phosphorylate BCL-2 during cell cycle progression as a normal physiologic process to inactivate BCL-2 at G2/M.

scholarly journals Ca2+cyt negatively regulates the initiation of oocyte maturation

2004 ◽  
Vol 165 (1) ◽  
pp. 63-75 ◽  
Author(s):  
Lu Sun ◽  
Khaled Machaca
Keyword(s):  
Cell Cycle ◽  
Oocyte Maturation ◽  
Cell Cycle Progression ◽  
Germinal Vesicle ◽  
Germinal Vesicle Breakdown ◽  
Cycle Progression ◽  
Nuclear Maturation ◽  
Oocyte Meiosis ◽  
Kinase Cascade ◽  
Cell Cycle Machinery

Ca2+ is a ubiquitous intracellular messenger that is important for cell cycle progression. Genetic and biochemical evidence support a role for Ca2+ in mitosis. In contrast, there has been a long-standing debate as to whether Ca2+ signals are required for oocyte meiosis. Here, we show that cytoplasmic Ca2+ (Ca2+cyt) plays a dual role during Xenopus oocyte maturation. Ca2+ signals are dispensable for meiosis entry (germinal vesicle breakdown and chromosome condensation), but are required for the completion of meiosis I. Interestingly, in the absence of Ca2+cyt signals oocytes enter meiosis more rapidly due to faster activation of the MAPK-maturation promoting factor (MPF) kinase cascade. This Ca2+-dependent negative regulation of the cell cycle machinery (MAPK-MPF cascade) is due to Ca2+cyt acting downstream of protein kinase A but upstream of Mos (a MAPK kinase kinase). Therefore, high Ca2+cyt delays meiosis entry by negatively regulating the initiation of the MAPK-MPF cascade. These results show that Ca2+ modulates both the cell cycle machinery and nuclear maturation during meiosis.

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 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.

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.

scholarly journals To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 861
Author(s):  
Veronika Kselíková ◽  
Vilém Zachleder ◽  
Kateřina Bišová
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Cell Cycle Progression ◽  
Model Organism ◽  
Cycle Progression ◽  
Synchronous Cultures ◽  
Multiple Fission ◽  
First Choice ◽  
High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

scholarly journals Analysis of Cell Cycle and Replication of Mouse Macrophages afterIn VivoandIn VitroCryptococcus neoformans Infection Using Laser Scanning Cytometry

2012 ◽  
Vol 80 (4) ◽  
pp. 1467-1478 ◽  
Author(s):  
Carolina Coelho ◽  
Lydia Tesfa ◽  
Jinghang Zhang ◽  
Johanna Rivera ◽  
Teresa Gonçalves ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cytotoxic Effect ◽  
Laser Scanning ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Content Type ◽  
Cycle Arrest ◽  
Laser Scanning Cytometry

ABSTRACTWe investigated the outcome of the interaction ofCryptococcus neoformanswith murine macrophages using laser scanning cytometry (LSC). Previous results in our lab had shown that phagocytosis ofC. neoformanspromoted cell cycle progression. LSC allowed us to simultaneously measure the phagocytic index, macrophage DNA content, and 5-ethynyl-2′-deoxyuridine (EdU) incorporation such that it was possible to study host cell division as a function of phagocytosis. LSC proved to be a robust, reliable, and high-throughput method for quantifying phagocytosis. Phagocytosis ofC. neoformanspromoted cell cycle progression, but infected macrophages were significantly less likely to complete mitosis. Hence, we report a new cytotoxic effect associated with intracellularC. neoformansresidence that manifested itself in impaired cell cycle completion as a consequence of a block in the G2/M stage of the mitotic cell cycle. Cell cycle arrest was not due to increased cell membrane permeability or DNA damage. We investigated alveolar macrophage replicationin vivoand demonstrated that these cells are capable of low levels of cell division in the presence or absence ofC. neoformansinfection. In summary, we simultaneously studied phagocytosis, the cell cycle state of the host cell and pathogen-mediated cytotoxicity, and our results demonstrate a new cytotoxic effect ofC. neoformansinfection on murine macrophages: fungus-induced cell cycle arrest. Finally, we provide evidence for alveolar macrophage proliferationin vivo.

scholarly journals A bulky glycocalyx fosters metastasis formation by promoting G1 cell cycle progression

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Elliot C Woods ◽  
FuiBoon Kai ◽  
J Matthew Barnes ◽  
Kayvon Pedram ◽  
Michael W Pickup ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Cells ◽  
Cell Cycle Progression ◽  
Disseminated Tumor Cells ◽  
Metastatic Potential ◽  
Cancer Cell Growth ◽  
Cycle Progression ◽  
Growth And Survival ◽  
Syngeneic Mouse Model

Metastasis depends upon cancer cell growth and survival within the metastatic niche. Tumors which remodel their glycocalyces, by overexpressing bulky glycoproteins like mucins, exhibit a higher predisposition to metastasize, but the role of mucins in oncogenesis remains poorly understood. Here we report that a bulky glycocalyx promotes the expansion of disseminated tumor cells in vivo by fostering integrin adhesion assembly to permit G1 cell cycle progression. We engineered tumor cells to display glycocalyces of various thicknesses by coating them with synthetic mucin-mimetic glycopolymers. Cells adorned with longer glycopolymers showed increased metastatic potential, enhanced cell cycle progression, and greater levels of integrin-FAK mechanosignaling and Akt signaling in a syngeneic mouse model of metastasis. These effects were mirrored by expression of the ectodomain of cancer-associated mucin MUC1. These findings functionally link mucinous proteins with tumor aggression, and offer a new view of the cancer glycocalyx as a major driver of disease progression.

scholarly journals Cdk1-Mediated Phosphorylation of Human ATF7 at Thr-51 and Thr-53 Promotes Cell-Cycle Progression into M Phase

PLoS ONE ◽  
2014 ◽  
Vol 9 (12) ◽  
pp. e116048 ◽  
Author(s):  
Hitomi Hasegawa ◽  
Kenichi Ishibashi ◽  
Shoichi Kubota ◽  
Chihiro Yamaguchi ◽  
Ryuzaburo Yuki ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
M Phase
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