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 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 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 Effect of emetine, a protein synthesis inhibitor, on larval tail resorption in the ascidian Halocynthia roretzi

2006 ◽  
Vol 23 (2) ◽  
pp. 43-46
Author(s):  
Kiyotaka Matsumura ◽  
Manami Nagano ◽  
Sachiko Tsukamoto ◽  
Haruko Kato ◽  
Nobuhiro Fusetani
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Halocynthia Roretzi

scholarly journals Local protein synthesis of neuronal MT1-MMP for agrin-induced presynaptic development

Development ◽  
2021 ◽  
Vol 148 (10) ◽  
Author(s):  
Jun Yu ◽  
Marilyn Janice Oentaryo ◽  
Chi Wai Lee
Keyword(s):  
Protein Synthesis ◽  
Neuronal Development ◽  
Neuromuscular Junctions ◽  
Neuronal Cell ◽  
Time Lapse ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Local Protein Synthesis ◽  
Presynaptic Differentiation ◽  
Local Protein

ABSTRACT Upon the stimulation of extracellular cues, a significant number of proteins are synthesized distally along the axon. Although local protein synthesis is crucial for various stages throughout neuronal development, its involvement in presynaptic differentiation at developing neuromuscular junctions remains unknown. By using axon severing and microfluidic chamber assays, we first showed that treatment of a protein synthesis inhibitor, cycloheximide, inhibits agrin-induced presynaptic differentiation in cultured Xenopus spinal neurons. Newly synthesized proteins are prominently detected, as revealed by the staining of click-reactive cell-permeable puromycin analog O-propargyl-puromycin, at agrin bead-neurite contacts involving the mTOR/4E-BP1 pathway. Next, live-cell time-lapse imaging demonstrated the local capturing and immobilization of ribonucleoprotein granules upon agrin bead stimulation. Given that our recent study reported the roles of membrane-type 1 matrix metalloproteinase (MT1-MMP) in agrin-induced presynaptic differentiation, here we further showed that MT1-MMP mRNA is spatially enriched and locally translated at sites induced by agrin beads. Taken together, this study reveals an essential role for axonal MT1-MMP translation, on top of the well-recognized long-range transport of MT1-MMP proteins synthesized from neuronal cell bodies, in mediating agrin-induced presynaptic differentiation.

Metaphase protein phosphorylation in Xenopus laevis eggs

1987 ◽  
Vol 7 (2) ◽  
pp. 760-768
Author(s):  
M J Lohka ◽  
J L Kyes ◽  
J L Maller
Keyword(s):  
Xenopus Laevis ◽  
Nuclear Envelope ◽  
Protein Phosphorylation ◽  
Tyrosine Kinases ◽  
Chromosome Condensation ◽  
Nuclear Envelope Breakdown ◽  
M Phase ◽  
Nuclear Events ◽  
Gamma S

Cytoplasmic extracts of metaphase (M-phase)-arrested Xenopus laevis eggs support nuclear envelope breakdown and chromosome condensation in vitro. Induction of nuclear breakdown is inhibited by AMPP(NH)P, a nonhydrolyzable ATP analog, but not by ATP or gamma-S-ATP, a hydrolyzable ATP analog, suggesting that protein phosphorylation may be required for M-phase nuclear events in vitro. By addition of [gamma-32P]ATP, we have identified in cytoplasmic extracts and in intact eggs at least six phosphoproteins that are present during M-phase but absent in G1/S-phase. These phosphoproteins also appear in response to partially purified preparations of maturation-promoting factor. A subset of these proteins are thiophosphorylated by gamma-S-ATP under conditions that promote nuclear envelope breakdown and chromosome condensation. Each of these proteins is phosphorylated on serine and threonine, and one, a 42-kilodalton protein, is also phosphorylated on tyrosine both in extracts and in intact eggs. These results indicate that activation of protein kinases accounts for at least part of the increased phosphorylation in M-phase and that both protein-serine-threonine kinases and protein-tyrosine kinases may play a role in controlling M-phase nuclear behavior.

Protein synthesis requirement of the Aplysia circadian clock. Tested by active and inactive derivatives of the inhibitor anisomycin

1980 ◽  
Vol 85 (1) ◽  
pp. 33-42
Author(s):  
J. W. Jacklet
Keyword(s):  
Protein Synthesis ◽  
Circadian Clock ◽  
Compound Action Potential ◽  
Phase Shifts ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Inhibitor Molecule ◽  
Group 5 ◽  
Characteristic Effect ◽  
Derivatives Of

1.The circadian rhythm of compound action potential frequency recorded from the isolated eye of Aplysia in culture medium and darkness was subjected to 6 h pulse treatments with either anisomycin, a protein synthesis inhibitor, or inactive derivatives of anisomycin. 2. Anisomycin caused phase-dependent phase shifts of the rhythm as expected from previous experiments, but none of the derivative molecules caused phase shifts or perturbed the rhythm. 3. Anisomycin inhibited eye-protein synthesis by 75% at the concentrations (10(−6) M) used in the phase shifting experiments but none of the derivatives inhibited synthesis. 4. Only those molecules that actually inhibited protein synthesis caused phase shifts of the clock, although the inactive derivatives differed from anisomycin by only an acetyl group. 5. The results strengthen the conclusion that the inhibition of protein synthesis caused by anisomycin is important in perturbing the timing of the circadian clock and not some other characteristic effect of the inhibitor molecule. Together with the results from other systems, these findings imply that the daily synthesis of protein is a general requirement for circadian clocks.

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