Effect of inhibitors of DNA replication on early zebrafish embryos: evidence for coordinate activation of multiple intrinsic cell-cycle checkpoints at the mid-blastula transition

Zygote ◽  
1997 ◽  
Vol 5 (2) ◽  
pp. 153-175 ◽  
Author(s):  
Richard Ikegami ◽  
Alma K. Rivera-Bennetts ◽  
Deborah L. Brooker ◽  
Thomas D. Yager
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Adaptive Response ◽  
Topoisomerase I ◽  
Topoisomerase Ii ◽  
Cell Cycle Checkpoints ◽  
Zebrafish Embryos ◽  
Replication Process ◽  
Inhibition Of Dna Synthesis

SummaryWe address the developmental activation, in the zebrafish embryo, of intrinsic cell-cycle checkpoints which monitor the DNA replication process and progression through the cell cycle. Eukaryotic DNA replication is probably carried out by a multiprotein complex containing numerous enzymes and accessory factors that act in concert to effect processive DNA synthesis (Applegren, N. et al. (1995) J. Cell. Biochem. 59, 91–107). We have exposed early zebrafish embryos to three chemical agents which are predicted to specifically inhibit the DNA polymerase α, topoisomerase I and topoisomerase II components of the DNA replication complex. We present four findings: (1) Before mid-blastula transition (MBT) an inhibition of DNA synthesis does not block cells from attempting to proceed through mitosis, implying the lack of functional checkpoints. (2) After MBT, the embryo displays two distinct modes of intrinsic checkpoint operation. One mode is a rapid and complete stop of cell division, and the other is an ‘adaptive’ response in which the cell cycle continues to operate, perhaps in a ‘repair’ mode, to generate daughter nuclei with few visible defects. (3) The embryo does not display a maximal capability for the ‘adaptive’ response until several hours after MBT, which is consistent with a slow rranscriptional control mechanism for checkpoint activation. (4) The slow activation of checkpoints at MBT provides a window of time during which inhibitors of DNA synthesis will induce cytogenetic lesions without killing the embryo. This could be useful in the design of a deletion-mutagenesis strategy.

scholarly journals Correlation between DNA synthesis in the second, third and fourth generations of spermatogonia and the occurrence of apoptosis in both spermatogonia and spermatocytes

Reproduction ◽  
2003 ◽  
pp. 661-668 ◽  
Author(s):  
J Blanco-Rodriguez ◽  
C Martinez-Garcia ◽  
A Porras
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Functional Significance ◽  
Tunel Assay ◽  
Seminiferous Epithelium ◽  
Cell Cycle Checkpoints ◽  
Clear Correlation ◽  
Cellular Events ◽  
Dna Strand

In the seminiferous epithelium, both DNA synthesis and apoptosis occur at equivalent stages in various species, with apoptosis taking place mainly at the same stages as DNA replication in the second, third and fourth spermatogonial generations. As preservation of the cellular associations found at these stages may have some functional significance, it is important to determine whether there is a correlation between these cellular events. In this study, pairs of immunoperoxidase-stained adjacent testis sections from rats, mice, rabbits and cats in which either bromodeoxyuridine incorporated into the newly synthesized DNA strand (BrdU labelling) or DNA 3' end labelling of the apoptotic DNA fragments (TUNEL assay) were detected were compared. In addition, both events were analysed in double-labelled sections. These two methods revealed a clear correlation between the occurrence of DNA replication in the second to fourth generations of spermatogonia and most physiological apoptosis taking place in both spermatogonia and spermatocytes in the three different mammalian orders (Rodentia, Lagomorpha and Carnivora). This correlation may result from the synchronization of mitotic spermatogonial and meiotic spermatocyte cell cycle checkpoints operating at these stages.

scholarly journals Human Exonuclease 1 (EXO1) Regulatory Functions in DNA Replication with Putative Roles in Cancer

2018 ◽  
Vol 20 (1) ◽  
pp. 74 ◽  
Author(s):  
Guido Keijzers ◽  
Daniela Bakula ◽  
Michael Petr ◽  
Nils Madsen ◽  
Amanuel Teklu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Dna Replication ◽  
Replication Fork ◽  
Cellular Transformation ◽  
Cell Cycle Checkpoints ◽  
Replication Process ◽  
Exonuclease 1 ◽  
Repair Pathways ◽  
Regulatory Functions

Human exonuclease 1 (EXO1), a 5′→3′ exonuclease, contributes to the regulation of the cell cycle checkpoints, replication fork maintenance, and post replicative DNA repair pathways. These processes are required for the resolution of stalled or blocked DNA replication that can lead to replication stress and potential collapse of the replication fork. Failure to restart the DNA replication process can result in double-strand breaks, cell-cycle arrest, cell death, or cellular transformation. In this review, we summarize the involvement of EXO1 in the replication, DNA repair pathways, cell cycle checkpoints, and the link between EXO1 and cancer.

Relationship between nucleoside triphosphate pools and DNA replication in the cell cycle of Escherichia coli

1974 ◽  
Vol 20 (5) ◽  
pp. 747-750 ◽  
Author(s):  
George G. Khachatourians ◽  
Lydia Huzyk
Keyword(s):  
Escherichia Coli ◽  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Specific Inhibitor ◽  
Replication Cycle ◽  
Nucleoside Triphosphate ◽  
E Coli ◽  
Synchronous Cultures ◽  
Inhibition Of Dna Synthesis

The correlation between DNA replication and the nucleoside triphosphate pool fluctuation in the cell cycle of Escherichia coli B/r was examined. 32P-labelled endogenous nucleoside triphosphates in normal synchronous cultures of E. coli B/r and those in which the chromosome replication cycle was inhibited by nalidixic acid, a specific inhibitor of DNA synthesis, were compared. No marked accumulation or depletion of nucleoside triphosphate pools was observed during the inhibition of DNA synthesis in the cell cycle. We suggest that changes in the pool levels during the cell cycle of E. coli occur independently of the DNA replication cycle.

scholarly journals Polycomb proteins control proliferation and transformation independently of cell cycle checkpoints by regulating DNA replication

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Andrea Piunti ◽  
Alessandra Rossi ◽  
Aurora Cerutti ◽  
Mareike Albert ◽  
Sriganesh Jammula ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Checkpoints ◽  
Polycomb Proteins

Relationship between chromatin structure and replication in mouse L-cells

1980 ◽  
Vol 58 (12) ◽  
pp. 1359-1369 ◽  
Author(s):  
Rose Sheinin ◽  
G. Setterfield ◽  
I. Dardick ◽  
G. Kiss ◽  
M. Dubsky
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
De Novo ◽  
Nuclear Volume ◽  
Chromatin Protein ◽  
Structural Reorganization ◽  
L Cells ◽  
Inhibition Of Dna Synthesis ◽  
De Novo Protein Synthesis ◽  
Nuclear Enlargement

Mouse L-cells treated with cytosine arabinoside, hydroxyurea, fluorodeoxyuridine, methotrexate, or mitomycin C rapidly cease DNA synthesis and stop dividing. Such inhibition of DNA replication is followed by interruption of formation of lysine- and arginine-containing proteins, including chromatin-bound histones, and by a major reorganization of the heterochromatin of the central nucleoplasm, manifest as disaggregation of large clumps of this condensed chromatin. Morphometric analysis revealed both cell and nuclear enlargement in cells treated with such antimetabolites of DNA replication. These observations are in contrast to those made with WT-4 cells starved of isoleucine or treated with cycloheximide. Isoleucine depletion was associated with inhibition of DNA synthesis and continued increase of cell and nuclear volume, but not with massive disaggregation of heterochromatin. Cycloheximide produced inhibition of DNA synthesis and protoplasmic growth, and also prevented structural reorganization of chromatin. A model is presented which suggests that initiation of chromatin replication is associated with a process, dependent upon de novo protein synthesis, which results in chromatin disaggregation. This can be revealed by inhibition of the correct replication of chromatin DNA and chromatin protein.

scholarly journals Nonperiodic Activity of the Human Anaphase-Promoting Complex–Cdh1 Ubiquitin Ligase Results in Continuous DNA Synthesis Uncoupled from Mitosis

2000 ◽  
Vol 20 (20) ◽  
pp. 7613-7623 ◽  
Author(s):  
Claus Storgaard Sørensen ◽  
Claudia Lukas ◽  
Edgar R. Kramer ◽  
Jan-Michael Peters ◽  
Jiri Bartek ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Kinase Inhibitor ◽  
Cyclin B1 ◽  
S Phase ◽  
Anaphase Promoting Complex

ABSTRACT Ubiquitin-proteasome-mediated destruction of rate-limiting proteins is required for timely progression through the main cell cycle transitions. The anaphase-promoting complex (APC), periodically activated by the Cdh1 subunit, represents one of the major cellular ubiquitin ligases which, in Saccharomyces cerevisiae andDrosophila spp., triggers exit from mitosis and during G1 prevents unscheduled DNA replication. In this study we investigated the importance of periodic oscillation of the APC-Cdh1 activity for the cell cycle progression in human cells. We show that conditional interference with the APC-Cdh1 dissociation at the G1/S transition resulted in an inability to accumulate a surprisingly broad range of critical mitotic regulators including cyclin B1, cyclin A, Plk1, Pds1, mitosin (CENP-F), Aim1, and Cdc20. Unexpectedly, although constitutively assembled APC-Cdh1 also delayed G1/S transition and lowered the rate of DNA synthesis during S phase, some of the activities essential for DNA replication became markedly amplified, mainly due to a progressive increase of E2F-dependent cyclin E transcription and a rapid turnover of the p27Kip1 cyclin-dependent kinase inhibitor. Consequently, failure to inactivate APC-Cdh1 beyond the G1/S transition not only inhibited productive cell division but also supported slow but uninterrupted DNA replication, precluding S-phase exit and causing massive overreplication of the genome. Our data suggest that timely oscillation of the APC-Cdh1 ubiquitin ligase activity represents an essential step in coordinating DNA replication with cell division and that failure of mechanisms regulating association of APC with the Cdh1 activating subunit can undermine genomic stability in mammalian cells.

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