Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The S/G2-specific transcription of the human cdc25C gene is due to the periodic occupation of a repressor element ('cell cycle-dependent element'; CDE) located in the region of the basal promoter. Protein binding to the major groove of the CDE in G0 and G1 results in a phase-specific repression of activated transcription. We now show that CDE-mediated repression is also the major principle underlying the periodic transcription of the human cyclin A and cdc2 genes. A single point mutation within the CDE results in a 10- to 20-fold deregulation in G0 and an almost complete loss of cell cycle regulation of all three genes. In addition, the cdc25C, cyclin A and cdc2 genes share an identical 5 bp region ('cell cycle genes homology region'; CHR) starting at an identical position, six nucleotides 3' to the CDE. Strikingly, mutation of the CHR region in each of the three promoters produces the same phenotype as the mutation of the CDE, i.e. a dramatic deregulation in G0. In agreement with these results, in vivo DMS footprinting showed the periodic occupation of the cyclin A CDE in the major groove, and of the CHR in the minor groove. Finally, all three genes bear conspicuous similarities in their upstream activating sequences (UAS). This applies in particular to the presence of NF-Y and Sp1 binding sites which, in the cdc25C gene, have been shown to be the targets of repression through the CDE.(ABSTRACT TRUNCATED AT 250 WORDS)
EMBO J 1995 Sep 15
PMID:Cell cycle regulation of the cyclin A, cdc25C and cdc2 genes is based on a common mechanism of transcriptional repression. 755 94

Defects in cellular differentiation are a common occurrence in human cancers. The combination of recombinant human fibroblast interferon (IFN-beta) and the antileukemic compound mezerein (MEZ) results in an irreversible loss of proliferative capacity and terminal cell differentiation in H0-1 human melanoma cells. In contrast, either agent alone induces reversible growth arrest and/or specific components of the differentiation process without inducing terminal differentiation. The current study investigates changes in cell cycle, cell cycle gene expression and E2F transcription factor complex formation during the processes of reversible and irreversible (terminal) differentiation. Induction of both terminal differentiation and reversible differentiation (MEZ treatment) results in a temporal decrease in DNA synthesis and the percentage of cells in S phase and a decrease in the expression of cell cycle and growth regulated genes, including cdc2, cyclin A, cyclin B, histone H1, histone H4, nm23-H1, p53 and c-myc. Persistent gene expression changes occur in terminally differentiated cells, but not in reversibly differentiated cells. H0-1 cells contain several E2F binding activities, including uncomplexed E2F, an E2F-p107-cyclin A-cdk2 kinase complex and an Rb-E2F complex. Induction of growth arrest by MEZ results in a slow migrating gelshift band that contains E2F associated with the pRb2/p130 protein. There is also a loss of the Rb-E2F complex. Induction of terminal differentiation after treatment with IFN-beta + MEZ generates a second pRb2/p130-E2F complex that migrates considerably faster than the pRb2/p130-E2F complex resulting from growth arrest. The slower migrating complex may contribute to growth arrest, whereas the faster migrating complex may play a role in terminal differentiation. Our results demonstrate that terminal cell differentiation involves a co-ordinate and continuous suppression of a number of cell cycle and growth related genes and results in the development of a novel E2F transcription factor complex not apparent in growth arrested and reversibly differentiated human melanoma cells.
Oncogene 1995 Sep 21
PMID:Cell cycle gene expression and E2F transcription factor complexes in human melanoma cells induced to terminally differentiate. 756 79

A mathematical model of cyclin E, cdk2 and retinoblastoma protein control of the G1 phase of the human cell cycle is proposed. The model includes retinoblastoma (Rb) protein phosphorylation by a cyclin E/cdk2 complex and its subsequent dephosphorylation at the end of the cell cycle. The numerical solutions to this model demonstrates the cyclic behavior of the cyclin E/cdk2 complex, with and without Rb function, cell cycle. This model suggests an inhibition of cyclin E/cdk2 complex formation (or its activation) by hypophosphorylated retinoblastoma protein. The experimental results of cell cycle arrest upon injection of transforming growth factor-beta, alpha-interferon or D-erythro-sphingosine during G1 phase are reproduced. Cell cycle behavior predicted by this model for increasing the concentration of hypophosphorylated retinoblastoma protein during the G1 phase is discussed. Additional results are obtained by numerical simulation.
Oncogene 1995 Sep 21
PMID:A model of the G1 phase of the cell cycle incorporating cyclin E/cdk2 complex and retinoblastoma protein. 756 81

Metazoan cyclin C was originally isolated by virtue of its ability to rescue Saccharomyces cerevisiae cells deficient in G1 cyclin function. This suggested that cyclin C might play a role in cell cycle control, but progress toward understanding the function of this cyclin has been hampered by the lack of information on a potential kinase partner. Here we report the identification of a human protein kinase, K35 [cyclin-dependent kinase 8 (CDK8)], that is likely to be a physiological partner of cyclin C. A specific interaction between K35 and cyclin C could be demonstrated after translation of CDKs and cyclins in vitro. Furthermore, cyclin C could be detected in K35 immunoprecipitates prepared from HeLa cells, indicating that the two proteins form a complex also in vivo. The K35-cyclin C complex is structurally related to SRB10-SRB11, a CDK-cyclin pair recently shown to be part of the RNA polymerase II holoenzyme of S. cerevisiae. Hence, we propose that human K35(CDK8)-cyclin C might be functionally associated with the mammalian transcription apparatus, perhaps involved in relaying growth-regulatory signals.
Proc Natl Acad Sci U S A 1995 Sep 12
PMID:Identification of human cyclin-dependent kinase 8, a putative protein kinase partner for cyclin C. 756 34

Cyclin B/cdc2 is responsible both for driving cells into mitosis and for activating the ubiquitin-dependent degradation of mitotic cyclins near the end of mitosis, an event required for the completion of mitosis and entry into interphase of the next cell cycle. Previous work with cell-free extracts of rapidly dividing clam embryos has identified two specific components required for the ubiquitination of mitotic cyclins: E2-C, a cyclin-selective ubiquitin carrier protein that is constitutively active during the cell cycle, and E3-C, a cyclin-selective ubiquitin ligase that purifies as part of a approximately 1500-kDa complex, termed the cyclosome, and which is active only near the end of mitosis. Here, we have separated the cyclosome from its ultimate upstream activator, cdc2. The mitotic, active form of the cyclosome can be inactivated by incubation with a partially purified, endogenous okadaic acid-sensitive phosphatase; addition of cdc2 restores activity to the cyclosome after a lag that reproduces that seen previously in intact cells and in crude extracts. These results demonstrate that activity of cyclin-ubiquitin ligase is controlled by reversible phosphorylation of the cyclosome complex.
Proc Natl Acad Sci U S A 1995 Sep 26
PMID:Reversible phosphorylation controls the activity of cyclosome-associated cyclin-ubiquitin ligase. 756 22

Abnormality of p53, a tumor suppressor gene, is considered to be a potential cause of malignancy. We found that ellipticine and 9-hydroxyellipticine (9HE), antitumor alkaloids, caused selective inhibition of p53 protein phosphorylation in Lewis lung carcinoma and SW480 (human colon cancer cell line) in a concentration-dependent manner from 0.1 to 100 microM. 9HE suppressed cdk2 kinase activity concentration-dependently from 1 to 100 microM. By contrast, the inhibition of p53 protein phosphorylation by elliptinium and elliprabin (N2 substituted derivatives of 9HE) was very weak. A good correlation was observed between p53 phosphorylation inhibition and cytotoxic activity of these agents in terms of concentration-response relationships, suggesting that inhibition of p53 protein phosphorylation via kinase inhibition may be involved in the anticancer mechanism of these agents. In addition, this study demonstrated that brief exposure to 9HE caused apoptosis of cancer cells. It is suggested that accumulation of dephosphorylated mutant p53 may induce apoptosis.
Jpn J Cancer Res 1995 Sep
PMID:Inhibition of p53 protein phosphorylation by 9-hydroxyellipticine: a possible anticancer mechanism. 759 58

Ionizing radiation causes a division delay in mammalian cells, dominated by a period of G2-phase arrest. The G2- to M-phase transition in dividing mammalian cells is dependent on the kinase activity of the cdc2-cyclin B protein complex. In the present investigation we measured the quantities of these two proteins, the formation of their complex and the kinase activity of the complex as a function of cell age in the cell cycle for irradiated and control mammalian cell populations. The human HeLa S3 cells were synchronized at the G1/S-phase border by double thymidine block and exposed 3 h after release to 1.75 Gy of X rays. Studies of HeLa cells at other laboratories have shown that, for doses of 5 Gy or more, division delay is associated with a suppression of production of cyclin B mRNA. Here we report that, for cells irradiated with low doses, there is a transient failure of the complex to activate which correlates with the duration of radiation-induced G2-phase arrest. The irradiated cells showed an increase in both cyclin B and phosphorylated cdc2 over the levels in control cells, and both persisted for a much longer period than in controls, further confirmation of delay in the activation of the catalytic subunit.
Radiat Res 1995 Sep
PMID:Transient failure to dephosphorylate the cdc2-cyclin B1 complex accompanies radiation-induced G2-phase arrest in HeLa cells. 765 66

The role of the C-terminal domain of CTP: phosphocholine cytidylyltransferase (CT) was explored by the creation of a series of deletion mutations in rat liver cDNA, which were expressed in COS cells as a major protein component. Deletion of up to 55 amino acids from the C-terminus had no effect on the activity of the enzyme, its stimulation by lipid vesicles or on its intracellular distribution between soluble and membrane-bound forms. However, deletion of the C-terminal 139 amino acids resulted in a 90% decrease in activity, loss of response to lipid vesicles and a significant decrease in the fraction of membrane-bound enzyme. Identification of the domain that is phosphorylated in vivo was determined by analysis of 32P-labelled CT mutants and by chymotrypsin proteolysis of purified CT that was 32P-labelled in vivo. Phosphorylation was restricted to the C-terminal 52 amino acids (domain P) and occurred on multiple sites. CT phosphorylation in vitro was catalysed by casein kinase II, cell division control 2 kinase (cdc2 kinase), protein kinases C alpha and beta II, and glycogen synthase kinase-3 (GSK-3), but not by mitogen-activated kinase (MAP kinase). Casein kinase II phosphorylation was directed exclusively to Ser-362. The sites phosphorylated by cdc2 kinase and GSK-3 were restricted to several serines within three proline-rich motifs of domain P. Sites phosphorylated in vitro by protein kinase C, on the other hand, were distributed over the N-terminal catalytic as well as the C-terminal regulatory domain. The stoichiometry of phosphorylation catalysed by any of these kinases was less than 0.2 mol P/mol CT, and no effects on enzyme activity were detected. This study supports a tripartite structure for CT with an N-terminal catalytic domain and a C-terminal regulatory domain comprised of a membrane-binding domain (domain M) and a phosphorylation domain (domain P). It also identifies three kinases as potential regulators in vivo of CT, casein kinase II, cyclin-dependent kinase and GSK-3.
Biochem J 1995 Sep 01
PMID:Functions of the C-terminal domain of CTP: phosphocholine cytidylyltransferase. Effects of C-terminal deletions on enzyme activity, intracellular localization and phosphorylation potential. 765 14

Iron removal by the chelating-agent deferoxamine (DFO) arrests cell cycle progression of activated human T cells in late G1 phase, before the G1/S border. The effects of the drug on molecules that regulate progression through the cell cycle were defined. DFO (10 mumol/L) inhibited induction of transcription of the cdc2 gene, but had no effect on accumulation of cdk2, cdk4, or interleukin (IL)-2-transcripts. No detectable p34cdc2 protein accumulated, but synthesis of the p33cdk2 protein was begun. It accumulated to normal levels during the first 20 to 30 hours of incubation in the presence of DFO. Furthermore, p33cdk2 was activated as an H1 histone kinase. As active p33cdk2 primarily represents complexes of the p33 protein with cyclin E or cyclin A, the effects of DFO on these cyclins were examined. Although the induction of synthesis and early accumulation of cyclin E and cyclin E-associated kinase activity appeared normal, the appearance of cyclin A and cyclin A-associated kinase activity were inhibited by DFO. However, the production of cyclin A mRNA appeared to be normal in the presence of DFO. A major effect of DFO in blocking cell cycle progression may be mediated through inhibition of the appearance of cyclin A protein and, therefore, a major component of p33cdk2 activity. The results also indicate that the p33cdk2/cyclin E activity produced in the presence of DFO was not sufficient for completion of the G1 phase of the cell cycle.
Blood 1995 Sep 15
PMID:Effects of iron-depletion on cell cycle progression in normal human T lymphocytes: selective inhibition of the appearance of the cyclin A-associated component of the p33cdk2 kinase. 766 74

Mammalian cell cycle progression is regulated by several protein kinases that are activated by cyclically expressed proteins called cyclins. These cyclin-dependent kinases, the prototype of which is the cdc2 mitosis-promoting kinase, are known to phosphorylate substrates the modified status of which is critical for the cell to progress into sequential phases of the cycle. Recently, a new cdc2-related protein kinase has been discovered. PISSLRE, named with respect to its homology to the cdc2 PSTAIRE amino acid domain. Here we report that by using both antisense and dominant-negative mutant constructs of PISSLRE when overexpressed in U2OS cells, a growth suppression is found. Furthermore, the dominant negative forms of PISSLRE halt cell cycle progression in G2-M. Therefore, PISSLRE is essential for cellular proliferation, and its effect is exerted in G2-M. This describes the first evidence since cdc2 of a cdc2-related kinase acting through G2-M.
Cancer Res 1995 Sep 15
PMID:The cdc-2-related kinase, PISSLRE, is essential for cell growth and acts in G2 phase of the cell cycle. 766 69


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