Cyclin E2, a Novel G1 Cyclin That Binds Cdk2 and Is Aberrantly Expressed in Human Cancers

ABSTRACT A novel cyclin gene was discovered by searching an expressed sequence tag database with a cyclin box profile. The human cyclin E2 gene encodes a 404-amino-acid protein that is most closely related to cyclin E. Cyclin E2 associates with Cdk2 in a functional kinase complex that is inhibited by both p27Kip1 and p21Cip1. The catalytic activity associated with cyclin E2 complexes is cell cycle regulated and peaks at the G1/S transition. Overexpression of cyclin E2 in mammalian cells accelerates G1, demonstrating that cyclin E2 may be rate limiting for G1 progression. Unlike cyclin E1, which is expressed in most proliferating normal and tumor cells, cyclin E2 levels were low to undetectable in nontransformed cells and increased significantly in tumor-derived cells. The discovery of a novel second cyclin E family member suggests that multiple unique cyclin E-CDK complexes regulate cell cycle progression.

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Liz1p, a Novel Fission Yeast Membrane Protein, Is Required for Normal Cell Division When Ribonucleotide Reductase Is Inhibited

Molecular Biology of the Cell ◽

10.1091/mbc.10.2.245 ◽

1999 ◽

Vol 10 (2) ◽

pp. 245-257 ◽

Cited By ~ 11

Author(s):

Elizabeth B. Moynihan ◽

Tamar Enoch

Keyword(s):

Cell Cycle ◽

Ribonucleotide Reductase ◽

Cell Cycle Progression ◽

Transmembrane Protein ◽

Reductase Activity ◽

Acid Protein ◽

Affect Cell Cycle Progression ◽

Transmembrane Transporters ◽

Ribonucleotide Reductase Activity ◽

Amino Acid Protein

Ribonucleotide reductase activity is required for generating deoxyribonucleotides for DNA replication. Schizosaccharomyces pombe cells lacking ribonucleotide reductase activity arrest during S phase of the cell cycle. In a screen for hydroxyurea-sensitive mutants in S. pombe, we have identified a gene,liz1 +, which when mutated reveals an additional, previously undescribed role for ribonucleotide reductase activity during mitosis. Inactivation of ribonucleotide reductase, by either hydroxyurea or a cdc22-M45 mutation, causesliz1 − cells in G2 to undergo an aberrant mitosis, resulting in chromosome missegregation and late mitotic arrest. liz1 + encodes a 514-amino acid protein with strong similarity to a family of transmembrane transporters, and localizes to the plasma membrane of the cell. These results reveal an unexpected G2/M function of ribonucleotide reductase and establish that defects in a transmembrane protein can affect cell cycle progression.

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Cell cycle control by Xenopus p28Kix1, a developmentally regulated inhibitor of cyclin-dependent kinases.

Molecular Biology of the Cell ◽

10.1091/mbc.7.3.457 ◽

1996 ◽

Vol 7 (3) ◽

pp. 457-469 ◽

Cited By ~ 47

Author(s):

W Shou ◽

W G Dunphy

Keyword(s):

Cell Cycle ◽

Mammalian Cells ◽

Cell Cycle Progression ◽

Cyclin E ◽

Cell Cycle Control ◽

Cyclin A ◽

Cyclin B ◽

Nuclear Antigen ◽

Cdk Inhibitors ◽

Egg Extracts

We have isolated Xenopus p28Kix1, a member of the p21CIP1/p27KIP1/p57KIP2 family of cyclin-dependent kinase (Cdk) inhibitors. Members of this family negatively regulate cell cycle progression in mammalian cells by inhibiting the activities of Cdks. p28 shows significant sequence homology with p21, p27, and p57 in its N-terminal region, where the Cdk inhibition domain is known to reside. In contrast, the C-terminal domain of p28 is distinct from that of p21, p27, and p57. In co-immunoprecipitation experiments, p28 was found to be associated with Cdk2, cyclin E, and cyclin A, but not the Cdc2/cyclin B complex in Xenopus egg extracts. Xenopus p28 associates with the proliferating cell nuclear antigen, but with a substantially lower affinity than human p21. In kinase assays with recombinant Cdks, p28 inhibits pre-activated Cdk2/cyclin E and Cdk2/cyclin A, but not Cdc2/cyclin B. However, at high concentrations, p28 does prevent the activation of Cdc2/cyclin B by the Cdk-activating kinase. Consistent with the role of p28 as a Cdk inhibitor, recombinant p28 elicits an inhibition of both DNA replication and mitosis upon addition to egg extracts, indicating that it can regulate multiple cell cycle transitions. The level of p28 protein shows a dramatic developmental profile: it is low in Xenopus oocytes, eggs, and embryos up to stage 11, but increases approximately 100-fold between stages 12 and 13, and remains high thereafter. The induction of p28 expression temporally coincides with late gastrulation. Thus, although p28 may play only a limited role during the early embryonic cleavages, it may function later in development to establish a somatic type of cell cycle. Taken together, our results indicate that Xenopus p28 is a new member of the p21/p27/p57 class of Cdk inhibitors, and that it may play a role in developmental processes.

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Raf-induced proliferation or cell cycle arrest is determined by the level of Raf activity with arrest mediated by p21Cip1.

Molecular and Cellular Biology ◽

10.1128/mcb.17.9.5598 ◽

1997 ◽

Vol 17 (9) ◽

pp. 5598-5611 ◽

Cited By ~ 452

Author(s):

D Woods ◽

D Parry ◽

H Cherwinski ◽

E Bosch ◽

E Lees ◽

...

Keyword(s):

Cell Cycle ◽

Cyclin D1 ◽

Cell Cycle Arrest ◽

Mammalian Cells ◽

Cell Cycle Progression ◽

Cyclin E ◽

G1 Arrest ◽

Cycle Progression ◽

Cycle Arrest ◽

Primary Mouse

The Raf family of protein kinases display differences in their abilities to promote the entry of quiescent NIH 3T3 cells into the S phase of the cell cycle. Although conditional activation of deltaA-Raf:ER promoted cell cycle progression, activation of deltaRaf-1:ER and deltaB-Raf:ER elicited a G1 arrest that was not overcome by exogenously added growth factors. Activation of all three deltaRaf:ER kinases led to elevated expression of cyclin D1 and cyclin E and reduced expression of p27Kip1. However, activation of deltaB-Raf:ER and deltaRaf-1:ER induced the expression of p21Cip1, whereas activation of deltaA-Raf:ER did not. A catalytically potentiated form of deltaA-Raf:ER, generated by point mutation, strongly induced p21Cip1 expression and elicited cell cycle arrest similarly to deltaB-Raf:ER and deltaRaf-1:ER. These data suggested that the strength and duration of signaling by Raf kinases might influence the biological outcome of activation of this pathway. By titration of deltaB-Raf:ER activity we demonstrated that low levels of Raf activity led to activation of cyclin D1-cdk4 and cyclin E-cdk2 complexes and to cell cycle progression whereas higher Raf activity elicited cell cycle arrest correlating with p21Cip1 induction and inhibition of cyclin-cdk activity. Using green fluorescent protein-tagged forms of deltaRaf-1:ER in primary mouse embryo fibroblasts (MEFs) we demonstrated that p21Cip1 was induced by Raf in a p53-independent manner, leading to cell cycle arrest. By contrast, activation of Raf in p21Cip1(-/-) MEFs led to a robust mitogenic response that was similar to that observed in response to platelet-derived growth factor. These data indicate that, depending on the level of kinase activity, Raf can elicit either cell cycle progression or cell cycle arrest in mouse fibroblasts. The ability of Raf to elicit cell cycle arrest is strongly associated with its ability to induce the expression of the cyclin-dependent kinase inhibitor p21Cip1 in a manner that bears analogy to alpha-factor arrest in Saccharomyces cerevisiae. These data are consistent with a role for Raf kinases in both proliferation and differentiation of mammalian cells.

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Cyclin E Associates with Components of the Pre-mRNA Splicing Machinery in Mammalian Cells

Molecular and Cellular Biology ◽

10.1128/mcb.18.8.4526 ◽

1998 ◽

Vol 18 (8) ◽

pp. 4526-4536 ◽

Cited By ~ 57

Author(s):

Wolfgang Seghezzi ◽

Katrin Chua ◽

Frances Shanahan ◽

Or Gozani ◽

Robin Reed ◽

...

Keyword(s):

Cell Cycle ◽

Mammalian Cells ◽

Cell Cycle Progression ◽

Cyclin E ◽

Specific Inhibitor ◽

Mrna Splicing ◽

Core Proteins ◽

Associated Proteins ◽

Cdk Regulation

ABSTRACT Cyclin E-cdk2 is a critical regulator of cell cycle progression from G1 into S phase in mammalian cells. Despite this important function little is known about the downstream targets of this cyclin-kinase complex. Here we have identified components of the pre-mRNA processing machinery as potential targets of cyclin E-cdk2. Cyclin E-specific antibodies coprecipitated a number of cyclin E-associated proteins from cell lysates, among which are the spliceosome-associated proteins, SAP 114, SAP 145, and SAP 155, as well as the snRNP core proteins B′ and B. The three SAPs are all subunits of the essential splicing factor SF3, a component of U2 snRNP. Cyclin E antibodies also specifically immunoprecipitated U2 snRNA and the spliceosome from splicing extracts. We demonstrate that SAP 155 serves as a substrate for cyclin E-cdk2 in vitro and that its phosphorylation in the cyclin E complex can be inhibited by the cdk-specific inhibitor p21. SAP 155 contains numerous cdk consensus phosphorylation sites in its N terminus and is phosphorylated prior to catalytic step II of the splicing pathway, suggesting a potential role for cdk regulation. These findings provide evidence that pre-mRNA splicing may be linked to the cell cycle machinery in mammalian cells.

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Quantitative Profiling of Adaptation to Cyclin E Overproduction

10.1101/2021.07.26.453751 ◽

2021 ◽

Author(s):

Juanita C Limas ◽

Aimee N. Littlejohn ◽

Amy M. House ◽

Katarzyna M Kedziora ◽

Dalia Fleifel ◽

...

Keyword(s):

Cell Cycle ◽

Mammalian Cells ◽

Cell Cycle Progression ◽

Cyclin E ◽

Genetic Alterations ◽

S Phase ◽

Gene Encoding ◽

Origin Licensing ◽

Dna Replication Origin ◽

Cell Cycle Dynamics

Cyclin E/CDK2 drives cell cycle progression from G1 to S phase. Cyclin E overproduction is toxic to mammalian cells, although the gene encoding cyclin E (CCNE1) is overexpressed in some cancers. It is not yet understood how cancer cells tolerate high levels of cyclin E. To address this question, we extensively characterized non-transformed epithelial cells subjected to chronic cyclin E overproduction. Cells overproducing human cyclin E briefly experienced truncated G1 phases, then consistently endured a transient period of DNA replication origin underlicensing, replication stress, and severely impaired proliferation. Individual cells displayed substantial intercellular heterogeneity in both cell cycle dynamics and CDK activity. Each of these phenotypes improved rapidly despite maintaining high cyclin E-associated activity. Transcriptome analysis revealed that adapted cells downregulated a cohort of G1-regulated genes. These cells also shared at least one unique change also found in breast tumors that overproduce cyclin E, expression of the cancer/testis antigen HORMAD1. Withdrawing cyclin E induction partially reversed the intermediate licensing phenotype of adapted cells indicating that adaptation is at least partly independent of genetic alterations. This study provides evidence that mammalian cyclin E/CDK inhibits origin licensing by an indirect mechanism through premature S phase onset. It serves as an example of specific oncogene adaptation that can identify key molecular changes during tumorigenesis.

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

Molecular and Cellular Biology ◽

10.1128/mcb.9.5.1940 ◽

1989 ◽

Vol 9 (5) ◽

pp. 1940-1945 ◽

Cited By ~ 14

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.

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A Novel Function for Cyclin E in Cell Cycle Progression

Hormonal Control of Cell Cycle - Research and Perspectives in Endocrine Interactions ◽

10.1007/978-3-540-73855-8_4 ◽

2007 ◽

pp. 31-39

Author(s):

Yan Geng ◽

Youngmi Lee ◽

Markus Welcker ◽

Jherek Swanger ◽

Agnieszka Zagozdzon ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Cyclin E ◽

Cycle Progression

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Computationally enhanced quantitative phase microscopy reveals autonomous oscillations in mammalian cell growth

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2002152117 ◽

2020 ◽

Vol 117 (44) ◽

pp. 27388-27399

Author(s):

Xili Liu ◽

Seungeun Oh ◽

Leonid Peshkin ◽

Marc W. Kirschner

Keyword(s):

Cell Cycle ◽

Growth Rate ◽

Cell Growth ◽

Mammalian Cells ◽

Cell Cycle Progression ◽

Cell Tracking ◽

Fundamental Property ◽

Quantitative Phase ◽

Phase Microscopy ◽

Quantitative Phase Microscopy

The fine balance of growth and division is a fundamental property of the physiology of cells, and one of the least understood. Its study has been thwarted by difficulties in the accurate measurement of cell size and the even greater challenges of measuring growth of a single cell over time. We address these limitations by demonstrating a computationally enhanced methodology for quantitative phase microscopy for adherent cells, using improved image processing algorithms and automated cell-tracking software. Accuracy has been improved more than twofold and this improvement is sufficient to establish the dynamics of cell growth and adherence to simple growth laws. It is also sufficient to reveal unknown features of cell growth, previously unmeasurable. With these methodological and analytical improvements, in several cell lines we document a remarkable oscillation in growth rate, occurring throughout the cell cycle, coupled to cell division or birth yet independent of cell cycle progression. We expect that further exploration with this advanced tool will provide a better understanding of growth rate regulation in mammalian cells.

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