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 alphavbeta3 integrin has been shown to promote cell migration through activation of intracellular signaling pathways. We describe here a novel pathway that modulates cell migration and that is activated by alphavbeta3 and, as downstream effector, by cdc2 (cdk1). We report that alphavbeta3 expression in LNCaP (beta3-LNCaP) prostate cancer cells causes increased cdc2 mRNA levels as evaluated by gene expression analysis, and increased cdc2 protein and kinase activity levels. We provide three lines of evidence that increased levels of cdc2 contribute to a motile phenotype on integrin ligands in different cell types. First, increased levels of cdc2 correlate with more motile phenotypes of cancer cells. Second, ectopic expression of cdc2 increases cell migration, whereas expression of dominant-negative cdc2 inhibits migration. Third, cdc2 inhibitors reduce cell migration without affecting cell adhesion. We also show that cdc2 increases cell migration via specific association with cyclin B2, and we unravel a novel pathway of cell motility that involves, downstream of cdc2, caldesmon. cdc2 and caldesmon are shown here to localize in membrane ruffles in motile cells. These results show that cdc2 is a downstream effector of the alphavbeta3 integrin, and that it promotes cell migration.
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PMID:Alpha(v)beta3 integrin expression up-regulates cdc2, which modulates cell migration. 1283 57

Our previous studies have shown that treatment of MCF-7 breast cancer cells with cytokine oncostatin M (OM) results in a growth arrest and a concurrent decrease in p53 expression. It remains to be determined whether these two important events are directly connected, as changes in p53 protein levels can lead to variable biological outcomes. In this study we have generated stable cell lines (MCF7-ptsp53) that express p53Val135 a p53 temperature-sensitive mutant. We demonstrate that overexpression of the wildtype (wt) p53 at permissive temperature in MCF7-ptsp53 cells leads to growth arrest at the G2-M phase of the cell cycle. Inhibition of endogenous p53 function with the expression of mutant p53 protein at non-permissive temperature did not affect the OM-induced G1 cell cycle arrest. Microarray studies were further carried out to identify p53- and OM-regulated genes that mediate the G2/M or G1 cell cycle arrest. We show that the expression of p21 was upregulated and expressions of cdc2, cyclin B2 and protein regulator of cytokinesis 1 (PRC1) were suppressed by overexpression of the wt p53 in MCF7-ptsp53 cells at the permissive temperature. In contrast, OM treatment caused coordinate changes of mRNA expression of several cell cycle components including c/EBPdelta, cdc20, and thymidine kinase 1 (TK1) that mainly affect G1-S phase transition. All together, our results suggest that the downregulation of p53 transcription may be involved in some other cellular changes induced by OM but it is not directly connected to the antiproliferative activity of OM per se.
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PMID:Molecular characterization of oncostatin M-induced growth arrest of MCF-7 cells expressing a temperature-sensitive mutant of p53. 1288 96

Cyclins are essential regulators of the cell division cycle. Cyclin B associates with the cyclin-dependent kinase 1 (cdc2) to form a complex which is required for cells to undergo mitosis. In mammalian cells three B-type cyclins have been characterised, cyclin B1, B2 and B3. The cell cycle-dependent synthesis of cyclin B1 and B2 has been investigated in detail displaying maximum expression in G2 which is mainly regulated on the transcriptional level. We have previously shown that this regulation of the mouse cyclin B2 promoter is controlled by a cell cycle-dependent element (CDE) and the cell cycle genes homology region (CHR). Also in a number of other genes CDE/CHR elements repress transcription in G0 and G1 and lead to relief of repression later during the cell cycle. Here, we compare human and mouse cyclin B2 promoters. Both promoters share only nine regions with nucleotide identities. Three of these sites are CCAAT-boxes spaced 33 bp apart which can bind the NF-Y transcriptional activator. NF-Y binding to the human cyclin B2 promoter could be shown by chromatin immunoprecipitation (ChIP) assays. Activation by NF-Y is responsible for more than 93% of the total promoter activity as measured by cotransfecting a plasmid coding for a dominant-negative form of NF-YA. Cell cycle-dependent repression is regulated solely through a CHR. Surprisingly, in contrast to the mouse promoter the CHR in the human cyclin B2 promoter does not rely on a CDE site in tandem with it. Together with the recently described mouse cdc25C promoter, human cyclin B2 is the second identified gene which solely requires a CHR for its cell cycle regulation.
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PMID:Three CCAAT-boxes and a single cell cycle genes homology region (CHR) are the major regulating sites for transcription from the human cyclin B2 promoter. 1290 59

Cyclins form complexes with cyclin-dependent kinases. By controlling activity of the enzymes, cyclins regulate progression through the cell cycle. A- and B-type cyclins were discovered due to their distinct appearance in S and G(2) phases and their rapid proteolytic destruction during mitosis. Transition from G(2) to mitosis is basically controlled by B-type cyclins. In mammals, two cyclin B proteins are well characterized, cyclin B1 and cyclin B2. Recently, a human cyclin B3 gene was described. In contrast to the expression pattern of other B-type cyclins, we find cyclin B3 mRNA expressed not only in S and G(2)/M cells but also in G(0) and G(1). Human cyclin B3 is expressed in different variants. We show that one isoform remains in the cytoplasm, whereas the other variant is translocated to the nucleus. Transport to the nucleus is dependent on three autonomous nonclassical nuclear localization signals that where previously not implicated in nuclear translocation. It had been shown that cyclin B3 coimmunoprecipitates with cdk2; but this complex does not exhibit any kinase activity. Furthermore, a degradation-resistant version of cyclin B3 can arrest cells in G(1) and G(2). Taken together with the finding that cyclin B3 mRNA is not only expressed in G(2)/M but is also detected in significant amounts in resting cells and in G(1) cells. This may suggest a dominant-negative function of human cyclin B3 in competition with activating cyclins in G(0) and the G(1) phase of the cell cycle.
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PMID:Human cyclin B3. mRNA expression during the cell cycle and identification of three novel nonclassical nuclear localization signals. 1662 5

Cyclin B is a regulatory subunit of CDK1 within MPF complex. Degradation of cyclin B via ubiquitin-proteasome pathway seemed to be absolutely required for the M-phase exit. However, inhibition of the proteasome proteolytic activity upon the exit from the meiotic metaphase II-arrest in Xenopus cell-free extract revealed that the proteasome-dependent dissociation of cyclin B from CDK1 is sufficient to inactivate MPF without cyclin B degradation. In this study we analyze whether the same mechanism operates during the exit from mitotic M-phase. We show in Xenopus cell-free extract undergoing the first or the second embryonic mitosis that CDK1 oscillations are not affected by proteasome inhibition with MG132 or ALLN despite effective inhibition of cyclins B degradation. The majority of cyclins B1 and B2 surviving CDK1 inactivation is CDK-free and cyclin B2 becomes resistant to phosphatase lambda dephosphorylation. The pool of cyclins B remaining after CDK1 inactivation in the presence of MG132 is mitotically inert, while exogenous or newly synthesized cyclin B activates CDK1. This suggests that cyclins B remain sequestered within the proteasome upon MPF inactivation in the presence of MG132. Comparison of the dynamics of the decline of total and CDK-bound pools of cyclins B1, B2 and B4 upon mitotic exit in absence of protein synthesis reveals that CDK-bound cyclins B diminish clearly faster. Our results thus show that cyclin B dissociation from CDK1 precedes cyclins B degradation upon CDK1 inactivation in mitotic embryo extracts and that proteasome proteolytic activity is dispensable for both activation and inactivation of CDK1 in such extracts.
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PMID:Cyclin B dissociation from CDK1 precedes its degradation upon MPF inactivation in mitotic extracts of Xenopus laevis embryos. 1692 Dec 58

Regulation of eukaryotic cell cycle progression requires sequential activation and inactivation of cyclin-dependent kinases. Previous RNA interference (RNAi) experiments in Trypanosoma brucei indicated that cyclin E1, cdc2-related kinase (CRK)1 and CRK2 are involved in regulating G1/S transition, whereas cyclin B2 and CRK3 play a pivotal role in controlling the G2/M checkpoint. To search for potential interactions between the other cyclins and CRKs that may not have been revealed by the RNAi assays, we used the yeast two-hybrid system and an in vitro glutathione-S-transferase pulldown assay and observed interactions between cyclin E1 and CRK1, CRK2 and CRK3. Cyclins E1-E4 are homologues of yeast Pho80 cyclin. But yeast complementation assays indicated that none of them possesses a Pho80-like function. Analysis of cyclin E1+CRK1 and cyclin E1+CRK2 double knockdowns in the procyclic form of T. brucei indicated that the cells were arrested more extensively in the G1 phase beyond the cumulative effect of individual knockdowns. But BrdU incorporation was impaired significantly only in cyclin E1+CRK1-depleted cells, whereas a higher percentage of cyclin E1+CRK2 knockdown cells assumed a grossly elongated posterior end morphology. A double knockdown of cyclin E1 and CRK3 arrested cells in G2/M much more efficiently than if only CRK3 was depleted. Taken together, these data suggest multiple functions of cyclin E1: it forms a complex with CRK1 in promoting G1/S phase transition; it forms a complex with CRK2 in controlling the posterior morphogenesis during G1/S transition; and it forms a complex with CRK3 in promoting passage across the G2/M checkpoint in the trypanosome.
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PMID:The multiple roles of cyclin E1 in controlling cell cycle progression and cellular morphology of Trypanosoma brucei. 1737 78

Multiple signals, controlling both proliferation and differentiation, must be integrated in the reprogramming of intestinal epithelial cells during maturation along the crypt-luminal axis. The v-myb family member Mybl2, a molecule implicated in the development and maintenance of the stem cell phenotype, has been suggested to play an important role in proliferation and differentiation of several cell types and is a gene we have found is commonly regulated in several systems of colon cell maturation both in vitro and in vivo. Here we show that siRNA silencing of Mybl2 in proliferating Caco-2 cells increases expression of the cell-cycle regulators cdk2, cyclin D2, and c-myc and decreases expression of cdc25B and cyclin B2 with a consequent 10% increase of cells in G2/M and a complementary 10% decrease in G1. Mybl2 occupies sequences upstream of transcriptional start sites of cyclin D2, c-myc, cyclin B2, and cdc25B and regulates reporter activity driven by upstream regions of cdk2, cyclin D2, and c-myc. These data suggest that Mybl2 plays a subtle but key role in linking specific aspects of cell-cycle progression with generation of signals for differentiation and may therefore be fundamental in commitment of intestinal epithelial cells to differentiation pathways during their maturation.
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PMID:MYBL2, a link between proliferation and differentiation in maturing colon epithelial cells. 2085 81

The CCAAT-binding transcription factor NF-Y plays a central role in regulating cellular proliferation by controlling the expression of genes required for cell-cycle progression such as cyclin A, cyclin B1, cyclin B2, cdc25A, cdc25C, and cdk1. Here we show that unrestricted NF-Y activity leads to apoptosis in an E2F1- and wild-type p53 (wtp53)-dependent manner. Unrestricted NF-Y activity induced an increase in E2F1 mRNA and protein levels. Furthermore, NF-Y directly bound the E2F1 promoter and this correlated with the appearance of open chromatin marks. The ability of NF-Y to induce apoptosis was impaired in cells lacking E2F1 and wtp53. Moreover, NF-Y overexpression elicited phosphorylation of wt p53Ser18 in an E2F1-dependent manner. Our findings establish that NF-Y acts upstream of E2F1 in p53-mediated apoptosis.
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PMID:Transcription factor NF-Y induces apoptosis in cells expressing wild-type p53 through E2F1 upregulation and p53 activation. 2095 9

Gene downregulation by antisense morpholino oligonucleotides (MOs) is achieved by either hybridization around the translation initiation codon or by targeting the splice donor site. In the present study, an antisense MO method is introduced that uses a 25-mer MO against a region at least 40-nt upstream from a poly(A) tail junction in the 3'-untranslated region (UTR) of maternal mRNA. The MO removed the poly(A) tail and blocked zebrafish cdk9 (zcdk9) mRNA translation, showing functional mimicry between miRNA and MO. A PCR-based assay revealed MO-mediated specific poly(A) tail removal of zebrafish mRNAs, including those for cyclin B1, cyclin B2 and tbp. The MO activity targeting cyclins A and B mRNAs was validated in unfertilized starfish oocytes and eggs. The MO removed the elongated poly(A) tail from maternal matured mRNA. This antisense method introduces a new application for the targeted downregulation of maternal mRNAs in animal oocytes, eggs and early embryos.
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PMID:Antisense morpholino targeting just upstream from a poly(A) tail junction of maternal mRNA removes the tail and inhibits translation. 2290 86

The circadian clock controls cell proliferation in a number of healthy tissues where cell renewal and regeneration are critical for normal physiological function. The intestine is an organ that typically undergoes regular cycles of cell division, differentiation and apoptosis as part of its role in digestion and nutrient absorption. The aim of this study was to explore circadian clock regulation of cell proliferation and cell cycle gene expression in the zebrafish intestine. Here we show that the zebrafish gut contains a directly light-entrainable circadian pacemaker, which regulates the daily timing of mitosis. Furthermore, this intestinal clock controls the expression of key cell cycle regulators, such as cdc2, wee1, p21, PCNA and cdk2, but only weakly influences cyclin B1, cyclin B2 and cyclin E1 expression. Interestingly, food deprivation has little impact on circadian clock function in the gut, but dramatically reduces cell proliferation, as well as cell cycle gene expression in this tissue. Timed feeding under constant dark conditions is able to drive rhythmic expression not only of circadian clock genes, but also of several cell cycle genes, suggesting that food can entrain the clock, as well as the cell cycle in the intestine. Rather surprisingly, we found that timed feeding is critical for high amplitude rhythms in cell cycle gene expression, even when zebrafish are maintained on a light-dark cycle. Together these results suggest that the intestinal clock integrates multiple rhythmic cues, including light and food, to function optimally.
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PMID:Circadian clock regulation of the cell cycle in the zebrafish intestine. 2401 5


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