New B-type cyclin synthesis is required between meiosis I and II duringXenopusoocyte maturation

Development ◽  
2001 ◽  
Vol 128 (19) ◽  
pp. 3795-3807 ◽  
Author(s):  
Helfrid Hochegger ◽  
Andrea Klotzbücher ◽  
Jane Kirk ◽  
Mike Howell ◽  
Katherine le Guellec ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Antisense Oligonucleotides ◽  
Kinase Activity ◽  
Meiotic Spindle ◽  
Cyclin Dependent Kinase ◽  
Metaphase Arrest ◽  
Meiotic Progression ◽  
New Protein ◽  
Meiosis I

Progression through meiosis requires two waves of maturation promoting factor (MPF) activity corresponding to meiosis I and meiosis II. Frog oocytes contain a pool of inactive ‘pre-MPF’ consisting of cyclin-dependent kinase 1 bound to B-type cyclins, of which we now find three previously unsuspected members, cyclins B3, B4 and B5. Protein synthesis is required to activate pre-MPF, and we show here that this does not require new B-type cyclin synthesis, probably because of a large maternal stockpile of cyclins B2 and B5. This stockpile is degraded after meiosis I and consequently, the activation of MPF for meiosis II requires new cyclin synthesis, principally of cyclins B1 and B4, whose translation is strongly activated after meiosis I. If this wave of new cyclin synthesis is ablated by antisense oligonucleotides, the oocytes degenerate and fail to form a second meiotic spindle. The effects on meiotic progression are even more severe when all new protein synthesis is blocked by cycloheximide added after meiosis I, but can be rescued by injection of indestructible B-type cyclins. B-type cyclins and MPF activity are required to maintain c-mos and MAP kinase activity during meiosis II, and to establish the metaphase arrest at the end of meiotic maturation. We discuss the interdependence of c-mos and MPF, and reveal an important role for translational control of cyclin synthesis between the two meiotic divisions.

scholarly journals Spatial and temporal control of targeting Polo-like kinase during meiotic prophase

2020 ◽  
Vol 219 (11) ◽  
Author(s):  
James N. Brandt ◽  
Katarzyna A. Hussey ◽  
Yumi Kim
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Meiotic Chromosome ◽  
Holocentric Chromosomes ◽  
Cyclin Dependent Kinase ◽  
Chromosome Dynamics ◽  
C Elegans ◽  
Meiotic Progression ◽  
Crossover Site ◽  
Meiosis I

Polo-like kinases (PLKs) play widely conserved roles in orchestrating meiotic chromosome dynamics. However, how PLKs are targeted to distinct subcellular localizations during meiotic progression remains poorly understood. Here, we demonstrate that the cyclin-dependent kinase CDK-1 primes the recruitment of PLK-2 to the synaptonemal complex (SC) through phosphorylation of SYP-1 in C. elegans. SYP-1 phosphorylation by CDK-1 occurs just before meiotic onset. However, PLK-2 docking to the SC is prevented by the nucleoplasmic HAL-2/3 complex until crossover designation, which constrains PLK-2 to special chromosomal regions known as pairing centers to ensure proper homologue pairing and synapsis. PLK-2 is targeted to crossover sites primed by CDK-1 and spreads along the SC by reinforcing SYP-1 phosphorylation on one side of each crossover only when threshold levels of crossovers are generated. Thus, the integration of chromosome-autonomous signaling and a nucleus-wide crossover-counting mechanism partitions holocentric chromosomes relative to the crossover site, which ultimately defines the pattern of chromosome segregation during meiosis I.

scholarly journals Proteostatic Signaling & Control of Protein Synthesis

2018 ◽  
Author(s):  
AJ Keefe
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Protein Misfolding ◽  
Granule Formation ◽  
Unfolded Protein ◽  
Mtorc1 Signaling ◽  
Control Translation ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
New Protein

The tremendous diversity and complexity of proteins invariably results in protein misfolding, to which cells have evolved numerous mechanisms of mitigating. Degrading misfolded proteins is perhaps the most intuitive strategy, but also critical to managing proteostasis are the elaborate mechanisms of translational control. Attenuated rates of translation ameliorate protein misfolding by downregulating the flux of new protein and conserving ATP. Loss of translational control, particularly in neurons, constitutes a major proteostatic dysfunction capable of causing or exacerbating neurodegeneration, while interventions aimed at downregulating protein synthesis are generally neuroprotective. In this review, I examine the critical neuronal signaling networks employed to control translation with an emphasis on current research. This includes the Unfolded Protein Response (UPR), the mitochondrial UPR (mtUPR), mTORC1 signaling, and stress granule formation.

scholarly journals Xenopus oocyte maturation does not require new cyclin synthesis.

1991 ◽  
Vol 114 (4) ◽  
pp. 767-772 ◽  
Author(s):  
J Minshull ◽  
A Murray ◽  
A Colman ◽  
T Hunt
Keyword(s):  
Protein Synthesis ◽  
Oocyte Maturation ◽  
Antisense Oligonucleotides ◽  
Xenopus Oocyte ◽  
Xenopus Oocytes ◽  
Cyclin A ◽  
Cyclin B1 ◽  
Meiotic Metaphase ◽  
Pass Through ◽  
Meiosis I

Progesterone induces fully grown, stage VI, Xenopus oocytes to pass through meiosis I and arrest in metaphase of meiosis II. Protein synthesis is required twice in this process: in order to activate maturation promoting factor (MPF) which induces meiosis I, and then again after the completion of meiosis I to reactivate MPF in order to induce meiosis II. We have used antisense oligonucleotides to destroy maternal stores of cyclin mRNAs, and demonstrate that new cyclin synthesis is not required for entry into either meiosis I or II. This finding is consistent with the demonstration that stage VI oocytes contain a store of B-type cyclin polypeptides (Kobayashi, H., J. Minshull, C. Ford, R. Golsteyn, R. Poon, and T. Hunt. 1991. J. Cell Biol. 114:755-765). Although approximately 70% of cyclin B2 is destroyed at first meiosis, the surviving fraction, together with a larger pool of surviving cyclin B1, must be sufficient to allow the reactivation of MPF and induce entry into second meiotic metaphase. Since stage VI oocytes do not contain any cyclin A, our results show that cyclin A is not required for meiosis in Xenopus. We discuss the possible nature of the proteins whose synthesis is required to induce meiosis I and II.

scholarly journals Proteostatic Signaling & Control of Protein Synthesis

2018 ◽  
Author(s):  
AJ Keefe
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Protein Misfolding ◽  
Granule Formation ◽  
Unfolded Protein ◽  
Mtorc1 Signaling ◽  
Control Translation ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
New Protein

The tremendous diversity and complexity of proteins invariably results in protein misfolding, to which cells have evolved numerous mechanisms of mitigating. Degrading misfolded proteins is perhaps the most intuitive strategy, but also critical to managing proteostasis are the elaborate mechanisms of translational control. Attenuated rates of translation ameliorate protein misfolding by downregulating the flux of new protein and conserving ATP. Loss of translational control, particularly in neurons, constitutes a major proteostatic dysfunction capable of causing or exacerbating neurodegeneration, while interventions aimed at downregulating protein synthesis are generally neuroprotective. In this review, I examine the critical neuronal signaling networks employed to control translation with an emphasis on current research. This includes the Unfolded Protein Response (UPR), the mitochondrial UPR (mtUPR), mTORC1 signaling, and stress granule formation.

Activation of bovine oocytes by protein synthesis inhibitors: new findings on the role of MPF/MAPKs†

2021 ◽  
Author(s):  
Cecilia Valencia ◽  
Felipe Alonso Pérez ◽  
Carola Matus ◽  
Ricardo Felmer ◽  
María Elena Arias
Keyword(s):  
Protein Synthesis ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Protein Synthesis Inhibitors ◽  
Vitro Fertilization ◽  
New Findings ◽  
Bovine Oocytes ◽  
Dependent Pathway

Abstract The present study evaluated the mechanism by which protein synthesis inhibitors activate bovine oocytes. The aim was to analyze the dynamics of MPF and MAPKs. MII oocytes were activated with ionomycin (Io), ionomycin+anisomycin (ANY) and ionomycin+cycloheximide (CHX) and by in vitro fertilization (IVF). The expression of cyclin B1, p-CDK1, p-ERK1/2, p-JNK, and p-P38 were evaluated by immunodetection and the kinase activity of ERK1/2 was measured by enzyme assay. Evaluations at 1, 4, and 15 hours postactivation (hpa) showed that the expression of cyclin B1 was not modified by the treatments. ANY inactivated MPF by p-CDK1Thr14-Tyr15 at 4 hpa (P < 0.05), CHX increased pre-MPF (p-CDK1Thr161 and p-CDK1Thr14-Tyr15) at 1 hpa and IVF increased p-CDK1Thr14-Tyr15 at 17 hours postfertilization (hpf) (P < 0.05). ANY and CHX reduced the levels of p-ERK1/2 at 4 hpa (P < 0.05) and its activity at 4 and 1 hpa, respectively (P < 0.05). Meanwhile, IVF increased p-ERK1/2 at 6 hpf (P < 0.05); however, its kinase activity decreased at 6 hpf (P < 0.05). p-JNK in ANY, CHX, and IVF oocytes decreased at 4 hpa (P < 0.05). p-P38 was only observed at 1 hpa, with no differences between treatments. In conclusion, activation of bovine oocytes by ANY, CHX, and IVF inactivates MPF by CDK1-dependent specific phosphorylation without cyclin B1 degradation. ANY or CHX promoted this inactivation, which seemed to be more delayed in the physiological activation (IVF). Both inhibitors modulated MPF activity via an ERK1/2-independent pathway, whereas IVF activated the bovine oocytes via an ERK1/2-dependent pathway. Finally, ANY does not activate the JNK and P38 kinase pathways.

scholarly journals The type 2 vascular endothelial growth factor receptor recruits insulin receptor substrate-1 in its signalling pathway

2002 ◽  
Vol 368 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Duraisamy SENTHIL ◽  
Goutam GHOSH CHOUDHURY ◽  
Basant K. BHANDARI ◽  
Balakuntalam S. KASINATH
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Protein Synthesis ◽  
Growth Factor ◽  
Epithelial Cells ◽  
Tyrosine Phosphorylation ◽  
Kinase Activity ◽  
Insulin Receptor Substrate ◽  
Vascular Endothelial ◽  
Endothelial Growth Factor

Vascular endothelial growth factor (VEGF) isoforms exert their biological effects through receptors that possess intrinsic tyrosine kinase activity. Whether VEGF binding to its receptors recruits insulin receptor substrate (IRS) family of docking proteins to the receptor is not known. Following incubation of mouse kidney proximal tubular epithelial cells with VEGF, we observed an increase in tyrosine phosphorylation of several proteins, including one of 200kDa, suggesting possible regulation of phosphorylation of IRS proteins. VEGF augmented tyrosine phosphorylation of IRS-1 in kidney epithelial cells and rat heart endothelial cells in a time-dependent manner. In the epithelial cells, association of IRS-1 with type 2 VEGF receptor was promoted by VEGF. VEGF also increased association of IRS-1 with the p85 regulatory subunit of phosphoinositide 3-kinase (PI 3-kinase), and PI 3-kinase activity in IRS-1 immunoprecipitates was increased in VEGF-treated cells. Incubation of epithelial cells with antisense IRS-1 oligonucleotide, but not sense oligonucleotide, reduced expression of the protein and VEGF-induced PI 3-kinase activity in IRS-1 immunoprecipitates. Additionally, VEGF-induced protein synthesis was also impaired by antisense but not sense IRS-1 oligonucleotide. These data provide the first evidence that binding of VEGF to its type 2 receptor promotes association of IRS-1 with the receptor complex. This association may account for some of the increase in VEGF-induced PI 3-kinase activity, and the increase in de novo protein synthesis seen in renal epithelial cells.

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