scholarly journals Grapes(Chk1) prevents nuclear CDK1 activation by delaying cyclin B nuclear accumulation

2008 ◽  
Vol 183 (1) ◽  
pp. 63-75 ◽  
Author(s):  
Anne Royou ◽  
Derek McCusker ◽  
Douglas R. Kellogg ◽  
William Sullivan
Keyword(s):  
Protein Synthesis ◽  
Drosophila Melanogaster ◽  
S Phase ◽  
Cyclin B ◽  
Nuclear Accumulation ◽  
Protein Synthesis Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Synthesis Inhibitor ◽  
Checkpoint Kinase 1 ◽  
Nuclear Envelope Breakdown

Entry into mitosis is characterized by a dramatic remodeling of nuclear and cytoplasmic compartments. These changes are driven by cyclin-dependent kinase 1 (CDK1) activity, yet how cytoplasmic and nuclear CDK1 activities are coordinated is unclear. We injected cyclin B (CycB) into Drosophila melanogaster embryos during interphase of syncytial cycles and monitored effects on cytoplasmic and nuclear mitotic events. In untreated embryos or embryos arrested in interphase with a protein synthesis inhibitor, injection of CycB accelerates nuclear envelope breakdown and mitotic remodeling of the cytoskeleton. Upon activation of the Grapes(checkpoint kinase 1) (Grp(Chk1))-dependent S-phase checkpoint, increased levels of CycB drives cytoplasmic but not nuclear mitotic events. Grp(Chk1) prevents nuclear CDK1 activation by delaying CycB nuclear accumulation through Wee1-dependent and independent mechanisms.

scholarly journals A Dual-Specificity Phosphatase Cdc25B Is an Unstable Protein and Triggers p34cdc2/Cyclin B Activation in Hamster BHK21 Cells Arrested with Hydroxyurea

1997 ◽  
Vol 138 (5) ◽  
pp. 1105-1116 ◽  
Author(s):  
Hitoshi Nishijima ◽  
Hideo Nishitani ◽  
Takashi Seki ◽  
Takeharu Nishimoto
Keyword(s):  
Protein Synthesis ◽  
S Phase ◽  
Cyclin B ◽  
Protein Synthesis Inhibitor ◽  
Temperature Sensitive ◽  
Synthesis Inhibitor ◽  
Dual Specificity ◽  
Dual Specificity Phosphatases ◽  
Initial Activation

By incubating at 30°C in the presence of an energy source, p34cdc2/cyclin B was activated in the extract prepared from a temperature-sensitive mutant, tsBN2, which prematurely enters mitosis at 40°C, the nonpermissive temperature (Nishimoto, T., E. Eilen, and C. Basilico. 1978. Cell. 15:475–483), and wild-type cells of the hamster BHK21 cell line arrested in S phase, without protein synthesis. Such an in vitro activation of p34cdc2/cyclin B, however, did not occur in the extract prepared from cells pretreated with protein synthesis inhibitor cycloheximide, although this extract still retained the ability to inhibit p34cdc2/cyclin B activation. When tsBN2 cells arrested in S phase were incubated at 40°C in the presence of cycloheximide, Cdc25B, but not Cdc25A and C, among a family of dual-specificity phosphatases, Cdc25, was lost coincidentally with the lack of the activation of p34cdc2/cyclin B. Consistently, the immunodepletion of Cdc25B from the extract inhibited the activation of p34cdc2/cyclin B. Cdc25B was found to be unstable (half-life < 30 min). Cdc25B, but not Cdc25C, immunoprecipitated from the extract directly activated the p34cdc2/cyclin B of cycloheximide-treated cells as well as that of nontreated cells, although Cdc25C immunoprecipitated from the extract of mitotic cells activated the p34cdc2/cyclin B within the extract of cycloheximide-treated cells. Our data suggest that Cdc25B made an initial activation of p34cdc2/cyclin B, which initiates mitosis through the activation of Cdc25C.

Regulation of human histone gene expression during the HeLa cell cycle requires protein synthesis

1984 ◽  
Vol 4 (12) ◽  
pp. 2723-2734
Author(s):  
H L Sive ◽  
N Heintz ◽  
R G Roeder
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
S Phase ◽  
Histone Gene ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibition ◽  
Synthesis Inhibitor ◽  
Synthesis Inhibition ◽  
Histone Mrnas ◽  
Histone Gene Expression

We have examined the effects of protein synthesis inhibition on histone gene expression during the HeLa cell cycle. Histone mRNAs, which normally are rapidly degraded in the absence of DNA synthesis, persist and increase in concentration when translation is inhibited before DNA replication is halted. This is not a function of polysomal shielding of these mRNAs from active degradation mechanisms since inhibitors of translation initiation alone effect stabilization and induction. The superinduction of histone mRNAs by protein synthesis inhibition is effective at the G1/S border, and in the S-phase and non-S-phase periods of the cell cycle. However, the relative increase in histone mRNA is greater when cells not synthesizing DNA are treated with a protein synthesis inhibitor than when S-phase cells are so treated. Non-histone mRNAs examined are not superinduced by translation inhibition. Transcription rates from both histone and non-histone genes increase after protein synthesis inhibition. Although the decrease in histone gene transcription associated with DNA synthesis inhibition is prevented and reversed by protein synthesis inhibition, we have no evidence that histone gene-specific transcriptional regulation is dependent on protein synthesis. Transcriptional increases may contribute to the superinduction effect but cannot explain its differential extent during the cell cycle, since these increases are similar when replicating or nonreplicating cells are treated with a protein synthesis inhibitor. We believe that changes in histone mRNA stability can account for much of the differential superinduction effect. Our results indicate a requirement for continuing protein synthesis in the cell cycle regulation of histone mRNAs.

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 DNA replication in Physarum polycephalum: electron microscopic analysis of patterns of DNA replication in the presence of cycloheximide.

1982 ◽  
Vol 95 (1) ◽  
pp. 323-331 ◽  
Author(s):  
F Haugli ◽  
R Andreassen ◽  
S Funderud
Keyword(s):  
Protein Synthesis ◽  
Dna Replication ◽  
Physarum Polycephalum ◽  
Replication Fork ◽  
Microscopic Analysis ◽  
S Phase ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Electron Microscopic ◽  
Replication Fork Progression

DNA from synchronously replicating nuclei of Physarum polycephalum was studied electron microscopically after 15, 30, 60, and 90 or 120 min of replication in the presence or absence of the protein synthesis inhibitor cycloheximide. The replication-loop size-distribution showed that replication fork progression is severely retarded in the presence of cycloheximide. Analysis of replication-loop frequency showed a similar pattern in control and cyclo-heximide-treated samples, with an increase from 15 to 30 and 60 min. This suggests, surprisingly, that initiations of new replicons either may not be inhibited by cycloheximide or, alternatively, that all initiations have already taken place at the very start of S-phase. The latter conclusion is favored in the light of previous results in our laboratory, discussed here.

scholarly journals Regulation of human histone gene expression during the HeLa cell cycle requires protein synthesis.

1984 ◽  
Vol 4 (12) ◽  
pp. 2723-2734 ◽  
Author(s):  
H L Sive ◽  
N Heintz ◽  
R G Roeder
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
S Phase ◽  
Histone Gene ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibition ◽  
Synthesis Inhibitor ◽  
Synthesis Inhibition ◽  
Histone Mrnas ◽  
Histone Gene Expression

We have examined the effects of protein synthesis inhibition on histone gene expression during the HeLa cell cycle. Histone mRNAs, which normally are rapidly degraded in the absence of DNA synthesis, persist and increase in concentration when translation is inhibited before DNA replication is halted. This is not a function of polysomal shielding of these mRNAs from active degradation mechanisms since inhibitors of translation initiation alone effect stabilization and induction. The superinduction of histone mRNAs by protein synthesis inhibition is effective at the G1/S border, and in the S-phase and non-S-phase periods of the cell cycle. However, the relative increase in histone mRNA is greater when cells not synthesizing DNA are treated with a protein synthesis inhibitor than when S-phase cells are so treated. Non-histone mRNAs examined are not superinduced by translation inhibition. Transcription rates from both histone and non-histone genes increase after protein synthesis inhibition. Although the decrease in histone gene transcription associated with DNA synthesis inhibition is prevented and reversed by protein synthesis inhibition, we have no evidence that histone gene-specific transcriptional regulation is dependent on protein synthesis. Transcriptional increases may contribute to the superinduction effect but cannot explain its differential extent during the cell cycle, since these increases are similar when replicating or nonreplicating cells are treated with a protein synthesis inhibitor. We believe that changes in histone mRNA stability can account for much of the differential superinduction effect. Our results indicate a requirement for continuing protein synthesis in the cell cycle regulation of histone mRNAs.

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
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