The jun and fos protein families are both required for cell cycle progression in fibroblasts

1991 ◽  
Vol 11 (9) ◽  
pp. 4466-4472
Author(s):  
K Kovary ◽  
R Bravo
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Stimulation Of

The expression of different members of the Jun and Fos families of transcription factors is rapidly induced following serum stimulation of quiescent fibroblasts. To determine whether these proteins are required for cell cycle progression, we microinjected affinity-purified antibodies directed against c-Fos, FosB, Fra-1, c-Jun, JunB, and JunD, and antibodies that recognize either the Fos or the Jun family of proteins, into Swiss 3T3 cells and determined their effects in cell cycle progression by monitoring DNA synthesis. We found that microinjection of anti-Fos and anti-Jun family antibodies efficiently blocked the entrance to the S phase of serum-stimulated or asynchronously growing cells. However, the antibodies against single members of the Fos family only partially inhibited DNA synthesis. In contrast, all three Jun antibodies prevented DNA synthesis more effectively than did any of the anti-Fos antibodies.

scholarly journals The jun and fos protein families are both required for cell cycle progression in fibroblasts.

1991 ◽  
Vol 11 (9) ◽  
pp. 4466-4472 ◽  
Author(s):  
K Kovary ◽  
R Bravo
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Stimulation Of

The expression of different members of the Jun and Fos families of transcription factors is rapidly induced following serum stimulation of quiescent fibroblasts. To determine whether these proteins are required for cell cycle progression, we microinjected affinity-purified antibodies directed against c-Fos, FosB, Fra-1, c-Jun, JunB, and JunD, and antibodies that recognize either the Fos or the Jun family of proteins, into Swiss 3T3 cells and determined their effects in cell cycle progression by monitoring DNA synthesis. We found that microinjection of anti-Fos and anti-Jun family antibodies efficiently blocked the entrance to the S phase of serum-stimulated or asynchronously growing cells. However, the antibodies against single members of the Fos family only partially inhibited DNA synthesis. In contrast, all three Jun antibodies prevented DNA synthesis more effectively than did any of the anti-Fos antibodies.

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.

scholarly journals Cell Cycle Dysregulation by Human Cytomegalovirus: Influence of the Cell Cycle Phase at the Time of Infection and Effects on Cyclin Transcription

1998 ◽  
Vol 72 (5) ◽  
pp. 3729-3741 ◽  
Author(s):  
Bryan S. Salvant ◽  
Elizabeth A. Fortunato ◽  
Deborah H. Spector
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Hcmv Infection ◽  
Cyclin A ◽  
S Phase ◽  
Cyclin B ◽  
Cycle Progression ◽  
Cycle Arrest ◽  
Time Of Infection

ABSTRACT Human cytomegalovirus (HCMV) infection inhibits cell cycle progression and alters the expression of cyclins E, A, and B (F. M. Jault, J.-M. Jault, F. Ruchti, E. A. Fortunato, C. Clark, J. Corbeil, D. D. Richman, and D. H. Spector, J. Virol. 69:6697–6704, 1995). In this study, we examined cell cycle progression, cyclin gene expression, and early viral events when the infection was initiated at different points in the cell cycle (G0, G1, and S). In all cases, infection led to cell cycle arrest. Cells infected in G0 or G1phase also showed a complete or partial absence, respectively, of cellular DNA synthesis at a time when DNA synthesis occurred in the corresponding mock-infected cells. In contrast, when cells were infected near or during S phase, many cells were able to pass through S phase and undergo mitosis prior to cell cycle arrest. S-phase infection also produced a delay in the appearance of the viral cytopathic effect and in the synthesis of immediate-early and early proteins. Labeling of cells with bromodeoxyuridine immediately prior to HCMV infection in S phase revealed that viral protein expression occurred primarily in cells which were not engaged in DNA synthesis at the time of infection. The viral-mediated induction of cyclin E, maintenance of cyclin-B protein levels, and inhibitory effects on the accumulation of cyclin A were not significantly affected when infection occurred during different phases of the cell cycle (G0, G1, and S). However, there was a delay in the observed inhibition of cyclin A in cells infected during S phase. This finding was in accord with the pattern of cell cycle progression and delay in viral gene expression associated with S-phase infection. Analysis of the mRNA revealed that the effects of the virus on cyclin E and cyclin A, but not on cyclin B, were primarily at the transcriptional level.

scholarly journals Distinct Signaling Pathways Mediate Stimulation of Cell Cycle Progression and Prevention of Apoptotic Cell Death by Estrogen in Rat Pituitary Tumor PR1 Cells

2003 ◽  
Vol 14 (12) ◽  
pp. 5051-5059 ◽  
Author(s):  
Simona Caporali ◽  
Manami Imai ◽  
Lucia Altucci ◽  
Massimo Cancemi ◽  
Silvana Caristi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Death ◽  
Dna Synthesis ◽  
Cell Survival ◽  
Pituitary Tumor ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Rat Pituitary ◽  
Stimulation Of

Estrogens control cell growth and viability in target cells via an interplay of genomic and extragenomic pathways not yet elucidated. Here, we show evidence that cell proliferation and survival are differentially regulated by estrogen in rat pituitary tumor PR1 cells. Pico- to femtomolar concentrations of 17β-estradiol (E2) are sufficient to foster PR1 cell proliferation, whereas nanomolar concentrations of the same are needed to prevent cell death that occurs at a high rate in these cells in the absence of hormone. Activation of endogenous (PRL) or transfected estrogen-responsive genes occurs at the same, higher concentrations of E2 required to promote cell survival, whereas stimulation of cyclin D3 expression and DNA synthesis occur at lower E2 concentrations. Similarly, the pure antiestrogen ICI 182,780 inhibits estrogen response element-dependent trans-activation and cell death more effectively than cyclin-cdk activity, G1-S transition, or DNA synthesis rate. In antiestrogen-treated and/or estrogen-deprived cells, death is due predominantly to apoptosis. Estrogen-induced cell survival, but not E2-dependent cell cycle progression, can be prevented by an inhibitor of c-Src kinase or by blockade of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling pathway. These data indicate the coexistence of two distinguishable estrogen signaling pathways in PR1 cells, characterized by different functions and sensitivity to hormones and antihormones.

scholarly journals Disruption of the Rb-Raf-1 Interaction Inhibits Tumor Growth and Angiogenesis

2004 ◽  
Vol 24 (21) ◽  
pp. 9527-9541 ◽  
Author(s):  
Piyali Dasgupta ◽  
Jiazhi Sun ◽  
Sheng Wang ◽  
Gina Fusaro ◽  
Vicki Betts ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Mitogen Activated Protein Kinase ◽  
Tubule Formation ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Quiescent Cells ◽  
Stimulation Of

ABSTRACT The retinoblastoma tumor suppressor protein (Rb) plays a vital role in regulating mammalian cell cycle progression and inactivation of Rb is necessary for entry into S phase. Rb is inactivated by phosphorylation upon growth factor stimulation of quiescent cells, facilitating the transition from G1 phase to S phase. Although the signaling events after growth factor stimulation have been well characterized, it is not yet clear how these signals contact the cell cycle machinery. We had found previously that growth factor stimulation of quiescent cells lead to the direct binding of Raf-1 kinase to Rb, leading to its inactivation. Here we show that the Rb-Raf-1 interaction occurs prior to the activation of cyclin and/or cyclin-dependent kinases and facilitates normal cell cycle progression. Raf-1-mediated inactivation of Rb is independent of the mitogen-activated protein kinase cascade, as well as cyclin-dependent kinases. Binding of Raf-1 seemed to correlate with the dissociation of the chromatin remodeling protein Brg1 from Rb. Disruption of the Rb-Raf-1 interaction by a nine-amino-acid peptide inhibits Rb phosphorylation, cell proliferation, and vascular endothelial growth factor-mediated capillary tubule formation. Delivery of this peptide by a carrier molecule led to a 79% reduction in tumor volume and a 57% reduction in microvessel formation in nude mice. It appears that Raf-1 links mitogenic signaling to Rb and that disruption of this interaction could aid in controlling proliferative disorders.

scholarly journals p15PAF Is an Rb/E2F-Regulated S-Phase Protein Essential for DNA Synthesis and Cell Cycle Progression

PLoS ONE ◽  
2013 ◽  
Vol 8 (4) ◽  
pp. e61196 ◽  
Author(s):  
Chih-Ning Chang ◽  
Mow-Jung Feng ◽  
Yu-Ling Chen ◽  
Ray-Hwang Yuan ◽  
Yung-Ming Jeng
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Cycle Progression ◽  
Phase Protein

scholarly journals Intracellular free Ca2+ in the cell cycle in human fibroblasts: transitions between G1 and G0 and progression into S phase.

1993 ◽  
Vol 4 (3) ◽  
pp. 293-302 ◽  
Author(s):  
M Wahl ◽  
E Gruenstein
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Dose Response ◽  
Human Fibroblasts ◽  
S Phase ◽  
Free Calcium ◽  
Response Curves ◽  
Serum Stimulation ◽  
Inhibition Of Dna Synthesis ◽  
Stimulation Of

Intracellular free calcium ([Ca2+]i) has been proposed to play an important part in the regulation of the cell cycle. Although a number of studies have shown that stimulation of quiescent cells with growth factors causes an immediate rise in [Ca2+]i (Rabinovitch et al., 1986; Vincentini and Villereal, 1986; Hesketh et al., 1988; Tucker et al., 1989, Wahl et al., 1990), a causal relationship between the [Ca2+]i transient and the ability of the cells to reenter the cell cycle has not been firmly established. We have found that blocking the mitogen-induced elevation of [Ca2+]i with the cytoplasmic [Ca2+]i buffer dimethyl BAPTA (dmBAPTA) also blocks subsequent entry of cells into S phase. The dose response curves for inhibition of serum stimulation of [Ca2+]i and DNA synthesis by dmBAPTA are virtually identical including an anomalous stimulation observed at low levels of dmBAPTA. Reversal of the [Ca2+]i buffering effect of dmBAPTA by transient exposure of the cells to the Ca2+ ionophore ionomycin also reverses the inhibition of DNA synthesis 20-24 h later. Ionomycin by itself does not stimulate DNA synthesis. These data are consistent with the conclusion that a transient increase in [Ca2+]i occurring shortly after serum stimulation of quiescent fibroblasts is necessary but not sufficient for subsequent entry of the cells into S phase. This study is the first to show a direct relationship between early serum stimulated Cai2+ increase and subsequent DNA synthesis in human cells. It also goes beyond recent studies on BALB/3T3 cells by providing dose response data and demonstrating reversibility, which are strong indications of a cause and effect relationship.

Existence of different Fos/Jun complexes during the G0-to-G1 transition and during exponential growth in mouse fibroblasts: differential role of Fos proteins

1992 ◽  
Vol 12 (11) ◽  
pp. 5015-5023
Author(s):  
K Kovary ◽  
R Bravo
Keyword(s):  
Exponential Growth ◽  
S Phase ◽  
3T3 Cells ◽  
Mouse Fibroblasts ◽  
Quiescent Cells ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Swiss 3T3 ◽  
Stimulation Of

We have determined the different Fos/Jun complexes present in Swiss 3T3 cells either following serum stimulation of quiescent cells or during exponential growth by immunoprecipitation analyses. We have shown that while c-Fos is the major Fos protein associated with the Jun proteins (c-Jun, JunB, and JunD) soon after serum stimulation, at later times Fra-1 and Fra-2 are the predominant Fos proteins associated with the different Jun proteins. During exponential growth, the synthesis of Fra-1 and Fra-2 is maintained at a significant level, in contrast to c-Fos and FosB, which are expressed at very low or undetectable levels. Consequently, Fra-1 and Fra-2 are the main Fos proteins complexed with the Jun proteins in asynchronously growing cells. To determine whether the Fos proteins are differentially required during the G0-to-G1 transition and exponential growth for the entrance into S phase, we microinjected affinity-purified antibodies directed against c-Fos, FosB, Fra-1, and Fra-2. We have found that while the activities of c-Fos and FosB are required mostly during the G0-to-G1 transition, Fra-1 and Fra-2 are involved both in the G0-to-G1 transition and in asynchronous growth.

scholarly journals Topoisomerase-specific drug sensitivity in relation to cell cycle progression.

1987 ◽  
Vol 7 (9) ◽  
pp. 3119-3123 ◽  
Author(s):  
K C Chow ◽  
W E Ross
Keyword(s):  
Cell Cycle ◽  
Dna Cleavage ◽  
Cell Cycle Progression ◽  
Topoisomerase Ii ◽  
Drug Sensitivity ◽  
S Phase ◽  
Synthesis Inhibitor ◽  
Drug Induced ◽  
Cycle Progression ◽  
Serum Stimulation

The nuclear enzyme DNA topoisomerase II catalyzes the breakage and resealing of duplex DNA and plays an important role in several genetic processes. It also mediates the DNA cleavage activity and cytotoxicity of clinically important anticancer agents such as etoposide. We have examined the activity of topoisomerase II during the first cell cycle of quiescent BALB/c 3T3 cells following serum stimulation. Etoposide-mediated DNA break frequency in vivo was used as a parameter of topoisomerase II activity, and enzyme content was assayed by immunoblotting. Density-arrested A31 cells exhibited a much lower sensitivity to the effects of etoposide than did actively proliferating cells. Upon serum stimulation of the quiescent cells, however, there was a marked increase in drug sensitivity which began during S phase and reached its peak just before mitosis. Maximal drug sensitivity during this period was 2.5 times greater than that of log-phase cells. This increase in drug sensitivity was associated with an increase in intracellular topoisomerase II content as determined by immunoblotting. The induction of topoisomerase II-mediated drug sensitivity was aborted within 1 h of exposure of cells to the protein synthesis inhibitor cycloheximide, but the DNA synthesis inhibitor aphidicolin had no effect. In contrast to the sensitivity of cells to drug-induced DNA cleavage, maximal cytotoxicity occurred during S phase. A 3-h exposure to cycloheximide before etoposide treatment resulted in nearly complete loss of cytotoxicity. Our findings indicate that topoisomerase II activity fluctuates with cell cycle progression, with peak activity occurring during the G2 phase. This increase in topoisomerase II is protein synthesis dependent and may reflect a high rate of enzyme turnover. The dissociation between maximal drug-induced DNA cleavage and cytotoxicity indicates that the topoisomerase-mediated DNA breaks may be necessary but are not sufficient for cytotoxicity and that the other factors which are particularly expressed during S phase may be important as well.

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