scholarly journals Density-dependent Growth Inhibition of Fibroblasts Ectopically Expressing p27kip1

2000 ◽  
Vol 11 (6) ◽  
pp. 2117-2130 ◽  
Author(s):  
Xiaohong Zhang ◽  
Walker Wharton ◽  
Marcia Donovan ◽  
Domenico Coppola ◽  
Rhonda Croxton ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Density ◽  
Ectopic Expression ◽  
High Density ◽  
Quiescent State ◽  
Low Density ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Tumor Virus ◽  
Dependent Growth

The cyclin/cyclin-dependent kinase (cdk) inhibitor p27kip1 is thought to be responsible for the onset and maintenance of the quiescent state. It is possible, however, that cells respond differently to p27kip1 in different conditions, and using a BALB/c-3T3 cell line (termed p27-47) that inducibly expresses high levels of this protein, we show that the effect of p27kip1 on cell cycle traverse is determined by cell density. We found that ectopic expression of p27kip1blocked the proliferation of p27-47 cells at high density but had little effect on the growth of cells at low density whether exponentially cycling or stimulated from quiescence. Regardless of cell density, the activities of cdk4 and cdk2 were markedly repressed by p27kip1 expression, as was the cdk4-dependent dissociation of E2F4/p130 complexes. Infection of cells with SV40, a DNA tumor virus known to abrogate formation of p130- and Rb-containing complexes, allowed dense cultures to proliferate in the presence of supraphysiological amounts of p27kip1 but did not stimulate cell cycle traverse when cultures were cotreated with the potent cdk2 inhibitor roscovitine. Our data suggest that residual levels of cyclin/cdk activity persist in p27kip1-expressing p27-47 cells and are sufficient for the growth of low-density cells and of high-density cells infected with SV40, and that effective disruption of p130 and/or Rb complexes is obligatory for the proliferation of high-density cultures.

scholarly journals p12DOC-1 Is a Novel Cyclin-Dependent Kinase 2-Associated Protein

2000 ◽  
Vol 20 (17) ◽  
pp. 6300-6307 ◽  
Author(s):  
Satoru Shintani ◽  
Hiroe Ohyama ◽  
Xue Zhang ◽  
Jim McBride ◽  
Kou Matsuo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Ectopic Expression ◽  
Cell Division Cycle ◽  
Cyclin Dependent Kinase ◽  
Data Support ◽  
Normal Keratinocytes ◽  
Active Pool ◽  
Growth Suppressor

ABSTRACT Regulated cyclin-dependent kinase (CDK) levels and activities are critical for the proper progression of the cell division cycle. p12DOC-1 is a growth suppressor isolated from normal keratinocytes. We report that p12DOC-1 associates with CDK2. More specifically, p12DOC-1 associates with the monomeric nonphosphorylated form of CDK2 (p33CDK2). Ectopic expression of p12DOC-1 resulted in decreased cellular CDK2 and reduced CDK2-associated kinase activities and was accompanied by a shift in the cell cycle positions of p12DOC-1transfectants (↑ G1 and ↓ S). The p12DOC-1-mediated decrease of CDK2 was prevented if the p12DOC-1 transfectants were grown in the presence of the proteosome inhibitor clasto-lactacystin β-lactone, suggesting that p12DOC-1 may target CDK2 for proteolysis. A CDK2 binding mutant was created and was found to revert p12DOC-1-mediated, CDK2-associated cell cycle phenotypes. These data support p12DOC-1 as a specific CDK2-associated protein that negatively regulates CDK2 activities by sequestering the monomeric pool of CDK2 and/or targets CDK2 for proteolysis, reducing the active pool of CDK2.

scholarly journals Growth Suppression by Acute PromyelocyticLeukemia-Associated Protein PLZF Is Mediated by Repression ofc-mycExpression

2003 ◽  
Vol 23 (24) ◽  
pp. 9375-9388 ◽  
Author(s):  
Melanie J. McConnell ◽  
Nathalie Chevallier ◽  
Windy Berkofsky-Fessler ◽  
Jena M. Giltnane ◽  
Rupal B. Malani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Cycle Arrest ◽  
Target Genes ◽  
Ectopic Expression ◽  
Growth Suppression ◽  
Quiescent State ◽  
Cycle Arrest

ABSTRACT The transcriptional repressor PLZF was identified by its translocation with retinoic acid receptor alpha in t(11;17) acute promyelocytic leukemia (APL). Ectopic expression of PLZF leads to cell cycle arrest and growth suppression, while disruption of normal PLZF function is implicated in the development of APL. To clarify the function of PLZF in cell growth and survival, we used an inducible PLZF cell line in a microarray analysis to identify the target genes repressed by PLZF. One prominent gene identified was c-myc. The array analysis demonstrated that repression of c-myc by PLZF led to a reduction in c-myc-activated transcripts and an increase in c-myc-repressed transcripts. Regulation of c-myc by PLZF was shown to be both direct and reversible. An interaction between PLZF and the c-myc promoter could be detected both in vitro and in vivo. PLZF repressed the wild-type c-myc promoter in a reporter assay, dependent on the integrity of the binding site identified in vitro. PLZF binding in vivo was coincident with a decrease in RNA polymerase occupation of the c-myc promoter, indicating that repression occurred via a reduction in the initiation of transcription. Finally, expression of c-myc reversed the cell cycle arrest induced by PLZF. These data suggest that PLZF expression maintains a cell in a quiescent state by repressing c-myc expression and preventing cell cycle progression. Loss of this repression through the translocation that occurs in t(11;17) would have serious consequences for cell growth control.

scholarly journals Two distinct ubiquitin-proteolysis pathways in the fission yeast cell cycle

1999 ◽  
Vol 354 (1389) ◽  
pp. 1551-1557 ◽  
Author(s):  
Takashi Toda ◽  
Itziar Ochotorena ◽  
Kin-ichiro Kominami
Keyword(s):  
Cell Cycle ◽  
Fission Yeast ◽  
Cell Cycle Control ◽  
Eukaryotic Cell ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Repeat Proteins ◽  
Cycle Dependent ◽  
Universal Mechanism

The SCF complex (Skp1-Cullin-1-F-box) and the APC/cyclosome (anaphase-promoting complex) are two ubiquitin ligases that play a crucial role in eukaryotic cell cycle control. In fission yeast F-box/WD-repeat proteins Pop1 and Pop2, components of SCF are required for cell-cycle-dependent degradation of the cyclin-dependent kinase (CDK) inhibitor Rum1 and the S-phase regulator Cdc18. Accumulation of these proteins in pop1 and pop2 mutants leads to re-replication and defects in sexual differentiation. Despite structural and functional similarities, Pop1 and Pop2 are not redundant homologues. Instead, these two proteins form heterodimers as well as homodimers, such that three distinct complexes, namely SCF Pop1/Pop1 , SCF Pop1/Pop2 and SCF Pop2/Pop2 , appear to exist in the cell. The APC/cyclosome is responsible for inactivation of CDK/cyclins through the degradation of B-type cyclins. We have identified two novel components or regulators of this complex, called Apc10 and Ste9, which are evolutionarily highly conserved. Apc10 (and Ste9), together with Rum1, are required for the establishment of and progression through the G1 phase in fission yeast. We propose that dual downregulation of CDK, one via the APC/cyclosome and the other via the CDK inhibitor, is a universal mechanism that is used to arrest the cell cycle at G1.

scholarly journals Cdk Phosphorylation of a Nucleoporin Controls Localization of Active Genes through the Cell Cycle

2010 ◽  
Vol 21 (19) ◽  
pp. 3421-3432 ◽  
Author(s):  
Donna Garvey Brickner ◽  
Jason H. Brickner
Keyword(s):  
Cell Cycle ◽  
Nuclear Periphery ◽  
S Phase ◽  
Nuclear Pore ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Initiation Of Dna Replication ◽  
Cdk Phosphorylation ◽  
Inducible Genes ◽  
Active Genes

Many inducible genes in yeast are targeted to the nuclear pore complex when active. We find that the peripheral localization of the INO1 and GAL1 genes is regulated through the cell cycle. Active INO1 and GAL1 localized at the nuclear periphery during G1, became nucleoplasmic during S-phase, and then returned to the nuclear periphery during G2/M. Loss of peripheral targeting followed the initiation of DNA replication and was lost in cells lacking a cyclin-dependent kinase (Cdk) inhibitor. Furthermore, the Cdk1 kinase and two Cdk phosphorylation sites in the nucleoporin Nup1 were required for peripheral targeting of INO1 and GAL1. Introduction of aspartic acid residues in place of either of these two sites in Nup1 bypassed the requirement for Cdk1 and resulted in targeting of INO1 and GAL1 to the nuclear periphery during S-phase. Thus, phosphorylation of a nuclear pore component by cyclin dependent kinase controls the localization of active genes to the nuclear periphery through the cell cycle.

scholarly journals Cyclin E restores p53 activity in contact-inhibited cells.

1995 ◽  
Vol 15 (7) ◽  
pp. 3926-3933 ◽  
Author(s):  
A Deffie ◽  
M Hao ◽  
R Montes de Oca Luna ◽  
D L Hulboy ◽  
G Lozano
Keyword(s):  
Cell Cycle ◽  
Cell Density ◽  
Transcriptional Activity ◽  
High Cell Density ◽  
P53 Protein ◽  
Cyclin E ◽  
Ectopic Expression ◽  
Contact Inhibition ◽  
High Cell ◽  
Inhibition Of Growth

The wild-type p53 protein is a potent growth suppressor when overexpressed in vitro. It functions as a transcriptional activator and causes growth arrest at the G1/S stage of the cell cycle. We monitored p53 transactivation as an indicator of p53 function throughout the cell cycle. We first demonstrate that cells which exhibited contact inhibition of growth lacked p53 transactivation function at high cell density. Since these cells were noncycling, we examined whether the ectopic expression of any cyclin could override contact inhibition of growth and restore p53 transactivation function. The transfection of cyclin E at high cell density stimulated the progression of cells through the cell cycle and restored p53 transactivation function. The transcriptional activity of p53 induced by cyclin E was regulated at the level of DNA binding. Cells that did not show contact inhibition of growth had a functional p53 regardless of cell density. Thus, contact inhibition of cell growth corresponded to a lack of p53 transactivation function and the overexpression of cyclin E in these contact-inhibited cells stimulated cell cycle progression and resulted in p53 transcriptional activity.

scholarly journals ATP Mediates Yeast Cell-Cell Communication

2020 ◽  
Author(s):  
Michael Caplow
Keyword(s):  
Cell Density ◽  
High Cell Density ◽  
Cell Communication ◽  
Growth Stimulation ◽  
High Density ◽  
Mutant Protein ◽  
Chromosome Loss ◽  
Low Density ◽  
High Cell ◽  
In Cells

AbstractYeast secrete ATP in response to glucose, a property with previously unknown functional consequence. In this report, we show that extracellular ATP is a signal for growth of surrounding cells. The ATP signaling behavior was uncovered by finding reduced toxicity of an inducible, dominant-lethal form of alpha tubulin (tub1-828) in cells grown at high, compared to low cell density. Reduced cell death at high cell density resulted because the rate of chromosome loss/cell division was lower (18-fold) in a cultures inoculated with a high density (350,000) compared to a low density (5,000) of cells. The sparing effect of growth at high cell density could be replicated by growing together 3440 cells that express tub1-828, with 2.3 E6 cells that do not express the mutant protein. Toxicity was reduced at high cell density apparently because a secreted signal induces growth, so that the mutant protein is rapidly diluted by synthesis of wild-type α-tubulin. Further, fluorescence-activated cell sorting (FACS) analysis after DNA staining showed that the rate of the G1-G2 transition was faster with cells at high density. ATP replaced the need for high cell density for resistance to tub1-828, and stimulated the transition from G1 to G2 in cells at low density. Cells lacking the enzyme nucleoside diphosphate kinase did not respond to nucleotide stimulation of growth during expression of mutant tubulin, suggesting that NDP kinase has a regulatory role in growth stimulation. This newly discovered quorum sensing response in yeast, mediated by ATP, indicates that yeast decision-making is not entirely autonomous.

Environmental control of the cell cycle in Drosophila: nutrition activates mitotic and endoreplicative cells by distinct mechanisms

Development ◽  
1998 ◽  
Vol 125 (11) ◽  
pp. 2149-2158 ◽  
Author(s):  
J.S. Britton ◽  
B.A. Edgar
Keyword(s):  
Cell Cycle ◽  
Fat Body ◽  
Environmental Control ◽  
Ectopic Expression ◽  
Cell Types ◽  
Quiescent State ◽  
Independent Manner ◽  
Cell Cycle Activation ◽  
E2f Transcription Factor

In newly hatched Drosophila larvae, quiescent cells reenter the cell cycle in response to dietary amino acids. To understand this process, we varied larval nutrition and monitored effects on cell cycle initiation and maintenance in the mitotic neuroblasts and imaginal disc cells, as well as the endoreplicating cells in other larval tissues. After cell cycle activation, mitotic and endoreplicating cells respond differently to the withdrawal of nutrition: mitotic cells continue to proliferate in a nutrition-independent manner, while most endoreplicating cells reenter a quiescent state. We also show that ectopic expression of Drosophila Cyclin E or the E2F transcription factor can drive quiescent endoreplicating cells, but not quiescent imaginal neuroblasts, into S-phase. Conversely, we demonstrate that quiescent imaginal neuroblasts, but not quiescent endoreplicating cells, can be induced to enter the cell cycle when co-cultured with larval fat body in vitro. These results demonstrate a fundamental difference in the control of cell cycle activation and maintenance in these two cell types, and imply the existence of a novel mitogen generated by the larval fat body in response to nutrition.

scholarly journals Autocrine signals enable chondrocytes to survive in culture.

1994 ◽  
Vol 126 (4) ◽  
pp. 1069-1077 ◽  
Author(s):  
Y Ishizaki ◽  
J F Burne ◽  
M C Raff
Keyword(s):  
Epithelial Cells ◽  
Cell Density ◽  
Mammalian Cells ◽  
Cell Types ◽  
High Density ◽  
Lens Epithelial Cells ◽  
Low Density ◽  
Cell Type ◽  
Adult Rats ◽  
And Cartilage

We recently proposed that most mammalian cells other than blastomeres may be programmed to kill themselves unless continuously signaled by other cells not to. Many observations indicate that some mammalian cells are programmed in this way, but is it the case for most mammalian cells? As it is impractical to test all of the hundreds of types of mammalian cells, we have focused on two tissues--lens and cartilage--which each contain only a single cell type: if there are cells that do not require signals from other cells to avoid programmed cell death (PCD), lens epithelial cells and cartilage cells (chondrocytes) might be expected to be among them. We have previously shown that rat lens epithelial cells can survive in serum-free culture without signals from other cell types but seem to require signals from other lens epithelial cells to survive: without such signals they undergo PCD. We show here that the same is true for rat (and chick) chondrocytes. They can survive for weeks in culture at high cell density in the absence of other cell types, serum, or exogenous proteins or signaling molecules, but they die with the morphological features of apoptosis in these conditions at low cell density. Medium from high density cultures, FCS, or a combination of known growth factors, all support prolonged chondrocyte survival in low density cultures, as long as antioxidants are also present. Moreover, medium from high density chondrocyte cultures promotes the survival of lens epithelial cells in low density cultures and vice versa. Chondrocytes isolated from adult rats behave similarly to those isolated from developing rats. These findings support the hypothesis that most mammalian cells require signals from other cells to avoid PCD, although the signals can sometimes be provided by cells of the same type, at least in tissues that contain only one cell type.

scholarly journals Alsterpaullone, a Cyclin-Dependent Kinase Inhibitor, Mediated Toxicity in HeLa Cells through Apoptosis-Inducing Effect

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Chunying Cui ◽  
Yuji Wang ◽  
Yaonan Wang ◽  
Ming Zhao ◽  
Shiqi Peng
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Cell Cycle Progression ◽  
Caspase 3 ◽  
Kinase Inhibitor ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Dose Dependent

Alsterpaullone, a small molecule cyclin-dependent kinase (CDK) inhibitor, regulates the cell cycle progression. Beyond death-inducing properties, we identified the effect of alsterpaullone on cycle procedure and apoptosis of HeLa cell. It was found that alsterpaullone inhibited HeLa cells in a time-dependent (0–72 h) and dose-dependent (0–30 μM) manner. In the presence of alsterpaullone, HeLa cells were arrested in G2/M prior to undergoing apoptosis via a mechanism that is involved in the regulation of various antiapoptotic genes, DNA-repair, transcription, and cell cycle progression. Compared to controls, alsterpaullone effectively prevented HeLa cells from entering S-phase. These potential therapeutic efficacies could be correlated with the activation of caspase-3.

Sign in / Sign up

Export Citation Format

Share Document