scholarly journals Differential response of cycling and noncycling cells to inducers of DNA synthesis and mitosis

1981 ◽  
Vol 88 (3) ◽  
pp. 649-653 ◽  
Author(s):  
PN Rao ◽  
ML Smith
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Uv Irradiation ◽  
Hela Cells ◽  
Cell Cycle Progression ◽  
Sendai Virus ◽  
Nonhistone Proteins ◽  
Interesting Observation ◽  
Human Diploid Fibroblasts ◽  
Kinetics Of

The objective of this study was to determine whether cells in G(0) phase are functionally distinct from those in G(1) with regard to their ability to respond to the inducers of DNA synthesis and to retard the cell cycle traverse of the G(2) component after fusion. Synchronized populations of HeLa cells in G(1) and human diploid fibroblasts in G(1) and G(0) phases were separately fused using UV-inactivated Sendai virus with HeLa cells prelabeled with [(3)H]ThdR and synchronized in S or G(2) phases. The kinetics of initiation of DNA synthesis in the nuclei of G(0) and G(1) cells residing in G(0)/S and G(1)/S dikaryons, respectively, were studied as a function of time after fusion. In the G(0)/G(2) and G(1)/G(2) fusions, the rate of entry into mitosis of the heterophasic binucleate cells was monitored in the presence of Colcemid. The effects of protein synthesis inhibition in the G(1) cells, and the UV irradiation of G(0) cells before fusion, on the rate of entry of the G(2) component into mitosis were also studied. The results of this study indicate that DNA synthesis can be induced in G(0)nuclei after fusion between G(0)- and S-phase cells, but G(0) nuclei are much slower than G(1) nuclei in responding to the inducers of DNA synthesis because the chromatin of G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells is more condensed than it is in G(1) cells. A more interesting observation resulting from this study is that G(0) cells differ from G(1) cells with regard to their effects on the cell cycle progression of the G(2) nucleus into mitosis. This difference between G(0) and G(1) cells appears to depend on certain factors, probably nonhistone proteins, present in G(1) cells but absent in G(0) cells. These factors can be induced in G(0) cells by UV irradiation and inhibited in G(1) cells by cycloheximide treatment.

Calmodulin-dependent protein kinase II is required for G1/S progression in HeLa cells

1995 ◽  
Vol 73 (3-4) ◽  
pp. 201-207 ◽  
Author(s):  
Grace Rasmussen ◽  
Colin Rasmussen
Keyword(s):  
Cell Cycle ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Hela Cells ◽  
Cell Cycle Progression ◽  
Dependent Protein Kinase ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Calmodulin Kinase ◽  
Dependent Protein

Calmodulin (CaM) has been previously shown to be essential for cell cycle progression in eukaryotic cells, being required at the G1/S,G2/M, and metaphase–anaphase transitions. Little is known about the specific CaM-dependent enzymes that mediate Ca2+/CaM signaling to affect cell proliferation. In this study we show that inhibition of calmodulin kinase II (CaMKII) in HeLa cells using the CaMKII inhibitor KN-93 causes cell cycle arrest, demonstrating that CaMKII is required for cell cycle progression. Detailed analysis of arrest cells suggests that CaMKII is required for the initiation of DNA synthesis. Cells treated with KN-93 arrest with a G1 DNA content, but with elevated cyclin-dependent histone H1 kinase activity, suggesting that CaMKII may act at a point very close to the onset of DNA synthesis in mammalian cells.Key words: calmodulin, protein kinase, cell cycle, HeLa.

scholarly journals Primase p49 mRNA expression is serum stimulated but does not vary with the cell cycle.

1989 ◽  
Vol 9 (5) ◽  
pp. 1940-1945 ◽  
Author(s):  
B Y Tseng ◽  
C E Prussak ◽  
M T Almazan
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Small Subunit ◽  
Mrna Levels ◽  
Proliferating Cells ◽  
Restriction Point ◽  
Serum Stimulation ◽  
G1 Cells

Expression of the small-subunit p49 mRNA of primase, the enzyme that synthesizes oligoribonucleotides for initiation of DNA replication, was examined in mouse cells stimulated to proliferate by serum and in growing cells. The level of p49 mRNA increased approximately 10-fold after serum stimulation and preceded synthesis of DNA and histone H3 mRNA by several hours. Expression of p49 mRNA was not sensitive to inhibition by low concentrations of cycloheximide, which suggested that the increase in mRNA occurred before the restriction point control for cell cycle progression described for mammalian cells and was not under its control. p49 mRNA levels were not coupled to DNA synthesis, as observed for the replication-dependent histone genes, since hydroxyurea or aphidicolin had no effect on p49 mRNA levels when added before or during S phase. These inhibitors did have an effect, however, on the stability of p49 mRNA and increased the half-life from 3.5 h to about 20 h, which suggested an interdependence of p49 mRNA degradation and DNA synthesis. When growing cells were examined after separation by centrifugal elutriation, little difference was detected for p49 mRNA levels in different phases of the cell cycle. This was also observed when elutriated G1 cells were allowed to continue growth and then were blocked in M phase with colcemid. Only a small decrease in p49 mRNA occurred, whereas H3 mRNA rapidly decreased, when cells entered G2/M. These results indicate that the level of primase p49 mRNA is not cell cycle regulated but is present constitutively in proliferating cells.

Demonstration of cell cycle kinetics in thyroid primary culture by immunostaining of proliferating cell nuclear antigen: differences in cyclic AMP-dependent and -independent mitogenic stimulations

1993 ◽  
Vol 105 (1) ◽  
pp. 69-80 ◽  
Author(s):  
M. Baptist ◽  
J.E. Dumont ◽  
P.P. Roger
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Primary Culture ◽  
Proliferating Cell Nuclear Antigen ◽  
Cell Cycle Progression ◽  
Nuclear Antigen ◽  
Major Influence ◽  
Cell Cycle Kinetics ◽  
Experimental Conditions ◽  
Proliferating Cell

In this study, experimental conditions are described that allowed us to follow the fate of the DNA polymerase delta-associated proliferating cell nuclear antigen (PCNA), by immunolabeling during the overall cell cycle. Differences in subcellular localization or the presence of PCNA allowed us to identify each phase of the cell cycle. Using these cell cycle markers in dog thyroid epithelial cells in primary culture, we found unexpected differences in cell cycle kinetics, in response to stimulations through cAMP-dependent and cAMP-independent pathways. These provide a new dimension to the view that the two pathways are largely separate, but co-operate on DNA synthesis initiation. More precisely, thyrotropin (TSH), acting via cAMP, exerts a potent triggering effect on DNA synthesis, associated with a precocious induction of PCNA appearance. This constitutes the major influence of TSH (cAMP) in determining cell cycle progression, which is only partly moderated by TSH-dependent lengthening of S- and G2-phases.

Replication and transcription sites are colocalized in human cells

1994 ◽  
Vol 107 (2) ◽  
pp. 425-434 ◽  
Author(s):  
A.B. Hassan ◽  
R.J. Errington ◽  
N.S. White ◽  
D.A. Jackson ◽  
P.R. Cook
Keyword(s):  
Cell Cycle ◽  
Confocal Microscopy ◽  
Dna Synthesis ◽  
Fluorescent Probes ◽  
Hela Cells ◽  
Nuclear Architecture ◽  
Human Cells ◽  
Dynamic Nature ◽  
Nucleotide Triphosphates ◽  
Transcription Sites

HeLa cells synchronized at different stages of the cell cycle were permeabilized and incubated with analogues of nucleotide triphosphates; then sites of incorporation were immunolabeled with the appropriate fluorescent probes. Confocal microscopy showed that sites of replication and transcription were not diffusely spread throughout nuclei, reflecting the distribution of euchromatin; rather, they were concentrated in ‘foci’ where many polymerases act together. Transcription foci aggregated as cells progressed towards the G1/S boundary; later they dispersed and became more diffuse. Replication was initiated only at transcription sites; later, when heterochromatin was replicated in enlarged foci, these remained sites of transcription. This illustrates the dynamic nature of nuclear architecture and suggests that transcription may be required for the initiation of DNA synthesis.

Landomycin a inhibits DNA synthesis and cell cycle progression

1999 ◽  
Vol 9 (12) ◽  
pp. 1663-1666 ◽  
Author(s):  
Robert T Crow ◽  
Betty Rosenbaum ◽  
Roger Smith ◽  
Yu Guo ◽  
Kenneth S Ramos ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Landomycin A

scholarly journals The in vitro effects of compound-X on growth, morphology, the induction of autophagy and apoptosis, as well as cell cycle progression in a cervical adenocarcinoma cell line

2012 ◽  
Vol 31 (1) ◽  
Author(s):  
S. Marais ◽  
T.V. Mqoco ◽  
B.A. Stander ◽  
R. Prudent ◽  
L. Lafanechère ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Hela Cells ◽  
Cell Cycle Progression ◽  
Cervical Adenocarcinoma ◽  
Growth Morphology ◽  
Adenocarcinoma Cell Line ◽  
Cycle Progression ◽  
Adenocarcinoma Cell

It can be concluded that compound-X induced both autophagy and apoptosis as a means of celldeath in HeLa cells.

scholarly journals Cellular Ras and Cyclin D1 Are Required during Different Cell Cycle Periods in Cycling NIH 3T3 Cells

1999 ◽  
Vol 19 (7) ◽  
pp. 4623-4632 ◽  
Author(s):  
Masahiro Hitomi ◽  
Dennis W. Stacey
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cyclin D1 ◽  
Cell Cycle Progression ◽  
Time Lapse ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

ABSTRACT Novel techniques were used to determine when in the cell cycle of proliferating NIH 3T3 cells cellular Ras and cyclin D1 are required. For comparison, in quiescent cells, all four of the inhibitors of cell cycle progression tested (anti-Ras, anti-cyclin D1, serum removal, and cycloheximide) became ineffective at essentially the same point in G1 phase, approximately 4 h prior to the beginning of DNA synthesis. To extend these studies to cycling cells, a time-lapse approach was used to determine the approximate cell cycle position of individual cells in an asynchronous culture at the time of inhibitor treatment and then to determine the effects of the inhibitor upon recipient cells. With this approach, anti-Ras antibody efficiently inhibited entry into S phase only when introduced into cells prior to the preceding mitosis, several hours before the beginning of S phase. Anti-cyclin D1, on the other hand, was an efficient inhibitor when introduced up until just before the initiation of DNA synthesis. Cycloheximide treatment, like anti-cyclin D1 microinjection, was inhibitory throughout G1 phase (which lasts a total of 4 to 5 h in these cells). Finally, serum removal blocked entry into S phase only during the first hour following mitosis. Kinetic analysis and a novel dual-labeling technique were used to confirm the differences in cell cycle requirements for Ras, cyclin D1, and cycloheximide. These studies demonstrate a fundamental difference in mitogenic signal transduction between quiescent and cycling NIH 3T3 cells and reveal a sequence of signaling events required for cell cycle progression in proliferating NIH 3T3 cells.

Mediators of the mitogenic action of human V1vascular vasopressin receptors

2000 ◽  
Vol 279 (5) ◽  
pp. H2529-H2539 ◽  
Author(s):  
Marc Thibonnier ◽  
Doreen M. Conarty ◽  
Christine L. Plesnicher
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Tritiated Thymidine ◽  
Chinese Hamster ◽  
Mitogen Activated Protein Kinase ◽  
Thymidine Uptake ◽  
Mitogenic Action

Arginine vasopressin (AVP) activation of V1 vascular receptors (V1Rs) stimulates cell growth and proliferation in different tissues via cellular signaling pathways that remain to be identified. To explore the intracellular mediators of the mitogenic action of V1R, Chinese hamster ovary (CHO) cells were stably transfected with the human V1R cDNA clone we isolated previously. We assessed AVP effects on kinase activation (immunoblotting with phosphospecific antibodies), DNA synthesis (tritiated thymidine uptake), cell cycle progression (flow cytometry analysis after nuclear labeling with propidium iodide), and cell proliferation (conversion of the colorimetric reagent MTS) in the presence or absence of various pathway inhibitors. AVP stimulation of V1Rs leads to the phosphorylation of several kinases, an increase in DNA synthesis, a progression through the S and G2–M phases of the cell cycle, and an increase in cell proliferation. The mediators of the mitogenic action of V1R activation included calcium mobilization, coupling to a Gq protein, and the simultaneous and parallel activation of several kinases, mainly calcium/calmodulin-dependent kinase II, phosphatidylinositol 3 kinase, protein kinase C, and p42/p44 mitogen-activated protein kinase.

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