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 The inhibition of nucleic acid synthesis by mycophenolic acid

1969 ◽  
Vol 113 (3) ◽  
pp. 515-524 ◽  
Author(s):  
T J Franklin ◽  
Jennifer M. Cook
Keyword(s):  
Dna Synthesis ◽  
Mycophenolic Acid ◽  
Early Stage ◽  
Acid Synthesis ◽  
Purine Nucleotides ◽  
Free System ◽  
L Cells ◽  
A Cell ◽  
Inhibition Of Dna Synthesis

1. Mycophenolic acid, an antibiotic of some antiquity that more recently has been found to have marked activity against a range of tumours in mice and rats, strongly inhibits DNA synthesis in the L strain of fibroblasts in vitro. 2. The extent of the inhibition of DNA synthesis is markedly increased by preincubation of the cells with mycophenolic acid before the addition of [14C]thymidine. 3. The inhibition of DNA synthesis by mycophenolic acid in L cells in vitro is reversed by guanine in a non-competitive manner, but not by hypoxanthine, xanthine or adenine. 4. The reversal of inhibition by guanine can be suppressed by hypoxanthine, 6-mercaptopurine and adenine. 5. Mycophenolic acid does not inhibit the incorporation of [14C]thymidine into DNA in suspensions of Landschütz and Yoshida ascites cells in vitro. 6. Mycophenolic acid inhibits the conversion of [14C]hypoxanthine into cold-acid-soluble and -insoluble guanine nucleotides in Landschütz and Yoshida ascites cells and also in L cells in vitro. There is some increase in the radioactivity of the adenine fraction in the presence of the antibiotic. 7. Mycophenolic acid inhibits the conversion of [14C]hypoxanthine into xanthine and guanine fractions in a cell-free system from Landschütz cells capable of converting hypoxanthine into IMP, XMP and GMP. 8. Preparations of IMP dehydrogenase from Landschütz ascites cells, calf thymus and LS cells are strongly inhibited by mycophenolic acid. The inhibition showed mixed type kinetics with Ki values of between 3·03×10−8 and 4·5×10−8m. 9. Evidence was also obtained for a partial, possibly indirect, inhibition by mycophenolic acid of an early stage of biosynthesis of purine nucleotides as indicated by a decrease in the accumulation of formylglycine amide ribonucleotide induced by the antibiotic azaserine in suspensions of Landschütz and Yoshida ascites cells and L cells in vitro.

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 Effect of inhibition of DNA synthesis on mating inEscherichia coliK12

1965 ◽  
Vol 6 (3) ◽  
pp. 479-483 ◽  
Author(s):  
Susan Hollom ◽  
R. H. Pritchard
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Amino Acid Starvation ◽  
The Other ◽  
Thymine Starvation ◽  
Other Hand ◽  
Inhibition Of Dna Synthesis ◽  
Polynucleotide Chain

From studies involving inhibition of DNA synthesis in Hfr strains ofEscherichia coliK12, either by thymine starvation (Pritchard, 1963) or amino-acid starvation (Suit, Matney, Doudney & Billen, 1964), during mating withF−strains, it has been concluded that transfer of DNA from males to females can occur in the absence of DNA synthesis. This conclusion is at variance with the hypothesis (Jacob, Brenner & Cuzin, 1963) that the energy required for transfer is derived from the process of DNA replication. On the other hand, a second prediction from this hypothesis, that one polynucleotide chain of the DNA transferred during mating will have been synthesized during transfer, is strongly supported by recent experiments (Ptashne, 1965; Blinkova, Bresler & Lanzov, 1965; Gross & Caro, 1965).

scholarly journals cAMP-mediated Inhibition of DNA Replication and S Phase Progression: Involvement of Rb, p21Cip1, and PCNA

2005 ◽  
Vol 16 (3) ◽  
pp. 1527-1542 ◽  
Author(s):  
Soheil Naderi ◽  
Jean Y.J. Wang ◽  
Tung-Ti Chen ◽  
Kristine B. Gutzkow ◽  
Heidi K. Blomhoff
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Cellular Proliferation ◽  
Kinase Activity ◽  
Antitumor Agents ◽  
Cell Types ◽  
S Phase ◽  
3T3 Fibroblasts ◽  
Phase Progression ◽  
Inhibition Of Dna Synthesis

cAMP exerts an antiproliferative effect on a number of cell types including lymphocytes. This effect of cAMP is proposed to be mediated by its ability to inhibit G1/S transition. In this report, we provide evidence for a new mechanism whereby cAMP might inhibit cellular proliferation. We show that elevation of intracellular levels of cAMP inhibits DNA replication and arrests the cells in S phase. The cAMP-induced inhibition of DNA synthesis was associated with the increased binding of p21Cip1to Cdk2-cyclin complexes, inhibition of Cdk2 kinase activity, dephosphorylation of Rb, and dissociation of PCNA from chromatin in S phase cells. The ability of cAMP to inhibit DNA replication and trigger release of PCNA from chromatin required Rb and p21Cip1proteins, since both processes were only marginally affected by increased levels of cAMP in Rb-/-and p21Cip1-/-3T3 fibroblasts. Importantly, the implications of cAMP-induced inhibition of DNA synthesis in cancer treatment was demonstrated by the ability of cAMP to reduce apoptosis induced by S phase–specific cytotoxic drugs. Taken together, these results demonstrate a novel role for cAMP in regulation of DNA synthesis and support a model in which activation of cAMP-dependent signaling protects cells from the effect of S phase–specific antitumor agents.

scholarly journals c-myc protein and DNA replication: separation of c-myc antibodies from an inhibitor of DNA synthesis.

1987 ◽  
Vol 7 (12) ◽  
pp. 4594-4598 ◽  
Author(s):  
C Gutierrez ◽  
Z S Guo ◽  
J Farrell-Towt ◽  
G Ju ◽  
M L DePamphilis
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Isolated Nuclei ◽  
Dna Polymerase Alpha ◽  
Inhibition Of Dna Synthesis ◽  
Antibody Preparations

Antibodies against human c-myc protein have been reported to inhibit DNA polymerase activity and endogenous DNA synthesis in isolated nuclei, suggesting a role for c-myc in DNA replication. Using the same antibody preparations, we observed equivalent inhibition of simian virus 40 DNA replication and DNA polymerase alpha and delta activities in vitro, as well as inhibition of DNA synthesis in isolated nuclei. However, the c-myc antibodies could be completely separated from the DNA synthesis inhibition activity. c-myc antibodies prepared in other laboratories also did not interfere with initiation of simian virus 40 DNA replication, DNA synthesis at replication forks, or DNA polymerase alpha or delta activity. Therefore, the previously reported inhibition of DNA synthesis by some antibody preparations resulted from the presence of an unidentified inhibitor of DNA polymerases alpha and delta and not from the action of c-myc antibodies.

scholarly journals DNA rearrangements in Euplotes crassus coincide with discrete periods of DNA replication during the polytene chromosome stage of macronuclear development.

1995 ◽  
Vol 15 (12) ◽  
pp. 6488-6495 ◽  
Author(s):  
J S Frels ◽  
C L Jahn
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Polytene Chromosome ◽  
Dna Sequences ◽  
Polytene Chromosomes ◽  
Single Locus ◽  
Dna Rearrangements ◽  
Macronuclear Development ◽  
Euplotes Crassus ◽  
Inhibition Of Dna Synthesis

Macronuclear development in Euplotes crassus begins with polytenization of micronuclear chromosomes and is accompanied by highly precise excision of DNA sequences known as internal eliminated sequences and transposon-like elements (Tecs). Quantitation of radiolabeled-precursor incorporation into DNA indicates that DNA synthesis during formation of polytene chromosomes is not continuous and occurs during two distinct periods. We demonstrate that the timing of Tec excision coincides with these replication periods and that excision can occur during both periods even at a single locus. We also show that Tec and internal eliminated sequence excisions are coincident in the second replication period, thus providing further evidence for similarity in their excision mechanism. Inhibition of DNA synthesis with hydroxyurea diminishes Tec element excision, indicating that replication is an important aspect of the excision process.

THE CHARACTERISTICS AND GENETIC MAP LOCATION OF A TEMPERATURE SENSITIVE DNA MUTANT OF E. COLI K12

Genetics ◽  
1972 ◽  
Vol 72 (4) ◽  
pp. 569-593
Author(s):  
Beverly Wolf
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Chain Elongation ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Bacterial Dna ◽  
E Coli ◽  
Dna Chain ◽  
Inhibition Of Dna Synthesis ◽  
Dna Mutant

ABSTRACT A temperature sensitive strain of E. coli K12 has been isolated in which residual DNA synthesis occurs at the 40°C restrictive temperature; syntheses of RNA, protein and DNA precursors are not directly affected. The mutation has been designated dna-325 and is located at 89 min on the E. coli map in the same region where the dnaC locus is found. dnaC mutants are considered to be defective in DNA initiation. Some of the data are consistent with the view that the dna-325 mutation is temperature sensitive in the process of DNA initiation rather than DNA chain elongation: (1) more than two cell divisions occur after a shift to 40°C; (2) upon a shift down to 30°C, cell division occurs again only after the DNA content of the cells has doubled; (3) 80% more DNA is made at 30°C in the presence of chloramphenicol after prior inhibition of DNA synthesis at 40°C. These three observations indicate that rounds of DNA replication were completed at 40°C. Also (4) infective λ particles can be made at 40°C long after bacterial DNA replication has ceased. It appears however that some DNA initiation can occur at 40°C since (1) a limited amount of DNA synthesis does occur at 40°C after prior alignment of the chromosomes by amino acid starvation at 30°C, and (2) after incubation in bromouracil at the restrictive temperature, heavy DNA is found with both strands containing bromouracil.

scholarly journals Cell Cycle-Regulated Expression of MammalianCDC6 Is Dependent on E2F

1998 ◽  
Vol 18 (11) ◽  
pp. 6679-6697 ◽  
Author(s):  
Guus Hateboer ◽  
Albrecht Wobst ◽  
Birgit Otzen Petersen ◽  
Laurent Le Cam ◽  
Elena Vigo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
De Novo ◽  
Rabbit Antiserum ◽  
S Phase ◽  
Resting Cells ◽  
Initiation Of Dna Replication

ABSTRACT The E2F transcription factors are essential regulators of cell growth in multicellular organisms, controlling the expression of a number of genes whose products are involved in DNA replication and cell proliferation. In Saccharomyces cerevisiae, the MBF and SBF transcription complexes have functions similar to those of E2F proteins in higher eukaryotes, by regulating the timed expression of genes implicated in cell cycle progression and DNA synthesis. TheCDC6 gene is a target for MBF and SBF-regulated transcription. S. cerevisiae Cdc6p induces the formation of the prereplication complex and is essential for initiation of DNA replication. Interestingly, the Cdc6p homolog inSchizosaccharomyces pombe, Cdc18p, is regulated by DSC1, the S. pombe homolog of MBF. By cloning the promoter for the human homolog of Cdc6p and Cdc18p, we demonstrate here that the cell cycle-regulated transcription of this gene is dependent on E2F. In vivo footprinting data demonstrate that the identified E2F sites are occupied in resting cells and in exponentially growing cells, suggesting that E2F is responsible for downregulating the promoter in early phases of the cell cycle and the subsequent upregulation when cells enter S phase. Our data also demonstrate that the human CDC6 protein (hCDC6) is essential and limiting for DNA synthesis, since microinjection of an anti-CDC6 rabbit antiserum blocks DNA synthesis and CDC6 cooperates with cyclin E to induce entry into S phase in cotransfection experiments. Furthermore, E2F is sufficient to induce expression of the endogenous CDC6 gene even in the absence of de novo protein synthesis. In conclusion, our results provide a direct link between regulated progression through G1controlled by the pRB pathway and the expression of proteins essential for the initiation of DNA replication.

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.

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