Accelerated G1-Transit Following Transient Inhibition of DNA Replication Is Dependent on Two Processes

Goswami, Prabhat C.; He, Weihua; Higashikubo, Ryuji; Roti, Joseph L. Roti

doi:10.1006/excr.1994.1249

Cited by 12 publications

(6 citation statements)

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“…Next, we measured the ability of the EL/CDK2 versus LMW-E/CDK2 complexes to phosphorylate full-length GST-Cdc25C. HeLa cells were used as they (i) do not have the machinery to process full-length cyclin E, (ii) have similar population doubling times to MCF-7 (24 hrs HeLa; 29 hrs MCF-7) and (iii) both have similar cell cycle profiles following release from aphidicolin arrest (24). EL or LMW-E were overexpressed in HeLa cells by adenoviral infection (Fig.…”

Section: Resultsmentioning

confidence: 99%

Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

et al. 2010

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The cyclin E-cyclin-dependent kinase 2 (CDK2) complex accelerates entry into the S phase of the cell cycle and promotes polyploidy, which may contribute to genomic instability in cancer cells. The effect of low molecular weight isoforms of cyclin E (LMW-E) overexpression on mitotic progression and its link to genomic instability were the focus of this study. Here, we show that full-length cyclin E (EL) and LMW-E overexpression impairs the G 2 -M transition differently by targeting dual-specificity phosphatase Cdc25C activity. We identify Cdc25C as an interaction partner and substrate for cyclin E/CDK2 kinase. Specifically, the cyclin E/CDK2 complex phosphorylates Cdc25C on Ser 214 , leading to its premature activation, which coincides with higher cyclin B/CDK1 and Polo-like kinase 1 (PLK1) activities in an S-phase-enriched population that result in faster mitotic entry. Whereas EL overexpression leads to hyperactivation of Cdc25C, cyclin B/CDK1, and PLK1 in a G 2 -M-enriched population, LMW-E overexpression causes premature inactivation of Cdc25C and PLK1, leading to faster mitotic exit. In addition, LMW-E-overexpressing cells showed a reduction in the mitotic index in the presence of a spindle poison and faster degradation of cyclin B, suggesting an increased rate of mitotic slippage and adaptation to the spindle checkpoint. Lastly, downregulation of Cdc25C inhibits LMW-E-mediated chromosome missegregation, anaphase bridges, and centrosome amplification. These results suggest that the high levels of LMW-E isoforms found in breast cancer may contribute to cellular transformation and genomic instability by impairing mitotic progression involving Cdc25C. Cancer Res; 70(12); 5085-95. ©2010 AACR.

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Section: Resultsmentioning

confidence: 99%

Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

et al. 2010

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“…The results (Fig. 1B) indicated that topoisomerase II␣ mRNA levels increased abruptly to 12-fold higher than G 1 levels between 10 and 12 h postmitosis (mid-S phase), subsequently peaking at 15-fold higher 16 h postmitosis (late S phase), and then de- To determine whether the increase in topoisomerase II␣ mRNA levels required progression through S phase, a Northern blot analysis was also carried out on synchronized cells treated with 3 M aphidicolin beginning 3 h after mitotic selection to block DNA synthesis (14). A propidium iodidestained univariant FCM analysis of cell cycle position indicated that this treatment blocked greater than 95% of the cells at the G 1 /S border (data not shown).…”

Section: Resultsmentioning

confidence: 99%

The Cell Cycle-Coupled Expression of Topoisomerase IIα during S Phase Is Regulated by mRNA Stability and Is Disrupted by Heat Shock or Ionizing Radiation

Goswami

Roti

Hunt

1996

Molecular and Cellular Biology

111

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Topoisomerase II is a multifunctional protein required during DNA replication, chromosome disjunction at mitosis, and other DNA-related activities by virtue of its ability to alter DNA supercoiling. The enzyme is encoded by two similar but nonidentical genes: the topoisomerase II␣ and II␤ genes. In HeLa cells synchronized by mitotic shake-off, topoisomerase II␣ mRNA levels were found to vary as a function of cell cycle position, being 15-fold higher in late S phase (14 to 18 h postmitosis) than during G 1 phase. Also detected was a corresponding increase in topoisomerase II␣ protein synthesis at 14 to 18 h postmitosis which resulted in significantly higher accumulation of the protein during S and G 2 phases. Topoisomerase II␣ expression was not dependent on DNA synthesis during S phase, which could be inhibited without effect on the timing or level of mRNA expression. Mechanistically, topoisomerase II␣ expression appears to be coupled to cell cycle position mainly through associated changes in mRNA stability. When cells are in S phase and mRNA levels are maximal, a half-life of greater than 4 h was observed. However, during G 1 phase, when cellular levels are lowest, the half-life of topoisomerase II␣ mRNA was determined to be approximately 30 min. A similar decrease in mRNA stability was also induced by two external factors known to delay cell cycle progression. Treatment of S-phase cells, at the time of maximum topoisomerase II␣ mRNA stability, with either ionizing radiation (5 Gy) or heat shock (45؇C for 15 min) caused the accumulated topoisomerase II␣ mRNA to decay. This finding suggests a potential relationship between stress-induced decreases in topoisomerase II␣ expression and cell cycle progression delays in late S/G 2 .The double-stranded nature of the DNA molecule presents special problems during chromosomal replication and segregation. Movement of the replication fork along the DNA molecule generates positive supercoiling in advance while the replicated parental strands in its wake are negatively supercoiled. Topological problems also arise near the end of replication when adjacent replication forks converge. Depending on the relative unwinding rate of the parental or progeny strands, either an intertwined or a gapped structure is formed (47). Unless untangled, the former structure leads to chromosome breakage, nondisjunction, and cell death (20). DNA topology in the cell is controlled through the action of two types of topoisomerase enzymes (see references 20 and 46 for reviews). Type I topoisomerases introduce into the duplex DNA molecule transient single-strand nicks which act as swivels during DNA replication or relieve the torsional stress associated with RNA transcription. Topoisomerase II enzymes relax, catenate, or decatenate DNA by introducing transient double-strand breaks which allow another DNA segment to pass through. While topoisomerase II is also capable, in theory, of relaxing transcription and replication induced supercoiling, it appears that topoisomerase I is mainly responsible for ...

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“…Progression of the cell cycle was monitored by flow cytometric analysis of bromodeoxyuridine (BrdU) incorporation vs. DNA content following a previously published procedure (13). Briefly, after 24 h of treatments with AODN or control ODN in serum-free medium, SMCs grown in 100-mm dishes were treated with or without PDGF-BB (10 ng/ml) for 6, 9, or 12 h. Cells were pulse-labeled with 10 M of BrdU (Sigma, St. Louis, MO) for 30 min.…”

Section: Methodsmentioning

confidence: 99%

Redox factor-1 contributes to the regulation of progression from G₀/G₁ to S by PDGF in vascular smooth muscle cells

He¹,

Weintraub²,

Goswami³

et al. 2003

American Journal of Physiology-Heart and Circulatory Physiology

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Accelerated G1-Transit Following Transient Inhibition of DNA Replication Is Dependent on Two Processes

Cited by 12 publications

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Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

The Cell Cycle-Coupled Expression of Topoisomerase IIα during S Phase Is Regulated by mRNA Stability and Is Disrupted by Heat Shock or Ionizing Radiation

Redox factor-1 contributes to the regulation of progression from G₀/G₁ to S by PDGF in vascular smooth muscle cells

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Accelerated G1-Transit Following Transient Inhibition of DNA Replication Is Dependent on Two Processes

Cited by 12 publications

References 0 publications

Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

Cyclin E Deregulation Impairs Mitotic Progression through Premature Activation of Cdc25C

The Cell Cycle-Coupled Expression of Topoisomerase IIα during S Phase Is Regulated by mRNA Stability and Is Disrupted by Heat Shock or Ionizing Radiation

Redox factor-1 contributes to the regulation of progression from G0/G1 to S by PDGF in vascular smooth muscle cells

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Redox factor-1 contributes to the regulation of progression from G₀/G₁ to S by PDGF in vascular smooth muscle cells