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

Multiple species of G1 cyclins and cyclin-dependent kinases are induced sequentially during G1 phase, and the expression of cyclin A and cdc2 genes is subsequently induced at the G1/S boundary. To analyze the mechanism of cdc2 promoter activation, the 5'-flanking region of the rat cdc2 gene was isolated and its structural features were characterized. The highly conserved sequence between human and rat cdc2 genes is present in the basal promoter region from positions -183 to -122, which contains the E box, SpI, and E2F motifs. The expression of 5' sequential deletion derivatives of the promoter fused to luciferase cDNA in rat 3Y1 cells revealed the presence of the enhancer element. The presumed enhancer region was further analyzed by the introduction of base substitutions and by the formation of DNA-protein complexes with cell extracts prepared at various times during the G1-to-S-phase progression. These analyses revealed that the enhancer sequence, AAGTTACAAATA, located from -276 to -265, confers strong inducibility on the basal promoter at the G1/S boundary. The base substitutions introduced into the motifs of transcription factors indicated that the E2F motif is essential for the enhancer-dependent activation of the cdc2 promoter at the G1/S boundary. Electrophoretic mobility shift assays and DNase I footprinting showed that a factor which interacts with the enhancer element is induced late in G1 phase.
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PMID:The G1/S boundary-specific enhancer of the rat cdc2 promoter. 773 68

Glucocorticoids inhibit transcription of the proto-oncogene c-myc in lymphoid cells of thymic origin. To determine if this effect is associated with changes in the properties of the transcription factor E2F, extracts were prepared from control and glucocorticoid-treated P1798 murine T lymphoma cells, and the macromolecular state of E2F was assessed by gel-mobility shift. Control extracts exhibit two predominant gel-mobility shift entities of which one corresponds to "free" E2F. A second entity, complex C, has properties similar to those described for the complex containing E2F, p107, cyclin A, and Cdk2. Complex C disappears after addition of dexamethasone and is replaced by complex D. The mobility of this complex and its sensitivity to SV40 T antigen suggest that complex D corresponds to an E2F-p105Rb-1 complex. Extracts from control and glucocorticoid-treated cells yield identical DNase I protection patterns on the c-myc P2 promoter. Furthermore, such extracts transcribe the c-myc P2 promoter in vitro with equal activity. The relative abundance of the E2F complexes was measured after addition of dexamethasone. Complex C disappears as cells withdraw from S phase, and complex D appears at this time. The genes encoding thymidine kinase (Tk-1) and p34cdc2 (cdc2) are regulated with kinetics similar to those observed for changes in the macromolecular state of E2F. However, regulation of c-myc expression occurs long before any change in E2F. The macromolecular state of E2F may regulate expression of genes at the G1/S boundary. However, the data are not consistent with the hypothesis that association of E2F with tumor suppressor gene products such as p107 or p105Rb-1 is relevant to glucocorticoid regulation of c-myc transcription.
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PMID:The macromolecular state of the transcription factor E2F and glucocorticoid regulation of c-myc transcription. 800 8

By performing DNase I footprint analysis, we had identified three distinct protein binding sequences (MT1, MT2, and MT3) located on the mouse thymidine kinase (TK) upstream promoter (Dou, Q.-P., Fridovich-Keil, J. L., and Pardee, A.B. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 1157-1161). Here we report that MT2 includes an E2F-like binding site (GTTCGCGGGCAAA), as shown by the following evidence. (i) MT2 bound specifically to an affinity-purified fusion human E2F protein. (ii) Both MT2 and an authentic E2F site (TTTCGCGCGCTTT) bound specifically to similar or identical nuclear protein complexes. (iii) Formation of both these DNA-protein complexes were cell cycle-dependent: a G0/G1 phase-specific complex (E2F.G0/G1) was replaced by an S phase-specific complex(es) (E2F.S), whereas "free" E2F increased after the G1/S transition. (iv) Pulse inhibition of protein synthesis with cycloheximide interchanged these complexes with similar kinetics. (v) When MT2-shifted E2F.G0/G1, E2F.S, and free E2F were eluted and analyzed by Western blot assay using a specific antiserum to human E2F-1, two forms of murine E2F (62 and 66 kDa) were observed from all three complexes. The compositions of these MT2-bound complexes were also investigated. Studies using specific antibodies revealed that p107, a retinoblastoma-like protein, was present in both E2F-G0/G1 and E2F.S, whereas cyclin E.cyclin A.cdk2 were only present in E2F.S complex(es). These data suggest that removal of the p107-containing E2F.G0/G1 complex, a candidate repressor, from the MT2 site in late G1 may be essential for S phase-dependent transcription of the mouse TK gene.
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PMID:G1/S-regulated E2F-containing protein complexes bind to the mouse thymidine kinase gene promoter. 828 95

To determine how myocardial terminal differentiation is regulated by cell cycle control genes, we studied cdc2 expression in rat cardiac muscle and found that cdc2 mRNA and protein levels were reduced in neonatal compared with fetal ventricles and became undetectable in juvenile and adult ventricles. To further determine whether cdc2 downregulation is attributed to a decrease in transcription, transient expression assay was performed using the progressively truncated 6.2-, 1.8-, 1.1-, 0.7-, and 0.1-kb human cdc2 5' flanking regions. All five fragments activated reporter expression in fetal myocytes and were significantly less active in neonatal myocytes. The 0.1-kb fragment showed 65% of the activity of the 6.2-kb fragment. A protein binding site that contains an inverted CCAAT box was identified within the 0.1-kb fragment by DNase I footprint assay and named the cdc2 promoter binding factor (CPBF) site. Point mutations within the CPBF site that abolish CPBF binding significantly decreased both 0.1- and 6.2-kb promoter activities. Competition and antibody supershift assays suggested that CPBF was identical or related to the transcription factor, nuclear factor Y (NF-Y). The 0.1-kb promoter activity was suppressed by a dominant-negative NF-Y mutant in fetal myocytes. Taken together, our results demonstrate that cardiac cdc2 expression is downregulated after birth and turned off when the juvenile stage is attained. A 0.1-kb promoter fragment of cdc2 contains major information for both cdc2 transcriptional activation and suppression in fetal and neonatal myocytes, respectively. NF-Y or its related factor plays a critical role in activating the 0.1-kb cdc2 promoter.
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PMID:Transcriptional activation of the p34cdc2 gene by cdc2 promoter binding factor/nuclear factor-Y in fetal rat ventricular myocytes. 946 96

Ribosomes prepared from somatic tissue of Xenopus laevis inhibit transcription by RNA polymerase III. This observation parallels an earlier report that a high speed fraction from activated egg extract, which is enrichedin ribosomes, inhibits RNA polymerase III activityand destabilizes putative transcription complexes assembled on oocyte 5S rRNA genes. Transcription of somatic- and oocyte-type 5S rRNA genes and a tRNA gene are all repressed in the present experiments. We find that 5S rRNA genes incubated in S150 extract prepared from immature oocytes exhibit an extensive DNase I protection pattern that is nearly identical to that of the ternary complex of TFIIIA and TFIIIC bound to a somatic 5S rRNA gene. The complexes formed in this extract are stable at concentrations of ribosomes that completely repress transcription, indicating that formation of the TFIII(A+C) complex is not the target of inhibition. Ribosomes taken through a high salt treatment no longer repress transcription of class III genes, establishing that the inhibition is due to an associated factor and not the particle itself. The inhibitory activity released from ribosomes is inactivated by treatment with proteinase K, but not micrococcal nuclease. Preincubation of ribosomes with a general protein kinase inhibitor, 6-dimethylaminopurine, eliminates repression of transcription. Western blot analysis demonstrates that p34(cdc2), which is known to mediate repression of transcription by RNA polymerase III, is present in these preparations of ribosomes and can be released from the particles upon extraction with high salt. These results establish that a kinase activity, possibly p34(cdc2), is the actual agent responsible for the observed inhibition of transcription by ribosomes.
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PMID:Inhibition of RNA polymerase III transcription by a ribosome-associated kinase activity. 975 46

Fumonisin B1 (FB1) is a food-borne mycotoxin produced by Fusarium moniliforme. Structurally FB1 resembles sphingoid bases, and ingestion of FB1 causes several animal diseases. FB1 will cause hepatic carcinoma in rats and is implicated as a cofactor in esophageal or hepatic carcinoma. Previous studies concluded that FB1 repressed cyclin-dependent kinase 2 (CDK2) activity but induced CDK inhibitors p21(Waf1/Cip1), p27(Kip1), and p57(Kip2) in monkey kidney cells (CV-1). In contrast, CV-1 cells transformed by simian virus 40 are resistant to the antiproliferative or apoptotic effects of FB1. Consequently, FB1 treatment of CV-1 cells leads to cell cycle arrest and apoptosis. In this study, we demonstrate that FB1 transcriptionally activates the p21 promoter. Functional analysis of the p21 promoter by reporter gene assays mapped the FB1-responsive region to -124 to -47. DNase I footprinting analysis revealed two protected motifs that span the FB1-responsive region, -124 to -101 (footprint II) and -89 to -67 (footprint III). Further studies demonstrated that DNA sequences from -124 to -101 were sufficient for FB1 stimulation. DNA sequences from -124 to -101 contain two Sp1 binding sites, and gel shift assays provided evidence that nuclear factors specifically bind to this region. Disruption of the two Sp1 binding sites abrogated the binding of nuclear proteins and prevented activation by FB1. Taken together, these results suggest that Sp1 or Sp1-related proteins mediate FB1-induced activation of the p21 promoter.
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PMID:The mycotoxin fumonisin B1 transcriptionally activates the p21 promoter through a cis-acting element containing two Sp1 binding sites. 1021 8

Gene expression of the plasminogen activation system is cell-cycle dependent. Previously, we showed that ectopic expression of E2F1 repressed the plasminogen activator inhibitor type 1 (PAI-1) promoter in a manner dependent on the presence of DNA-binding and transactivation domains of E2F1 but independent of binding to pocket-binding proteins, suggesting a novel mechanism for E2F-mediated negative gene regulation [Koziczak, M., Krek, W. & Nagamine, Y. (2000) Mol. Cell. Biol. 20, 2014-2022]. However, it remains to be seen whether endogenous E2F can exert a similar effect. We report here that down-regulation of PAI-1 gene expression correlates with an increase in endogenous E2F activity. When cells were treated with a cdk2/4-specific inhibitor, which maintains E2F in an inactive state, the decline of serum-induced PAI-1 mRNA levels was suppressed. In mutant U2OS cells expressing a temperature-sensitive retinoblastoma protein (pRB), a shift to a permissive temperature induced PAI-1 mRNA expression. In U2OS cells stably expressing an E2F1-estrogen receptor chimeric protein that could be activated by tamoxifen, PAI-1 gene transcription was markedly reduced by tamoxifen even in the presence of cycloheximide. These results all indicate that endogenous E2F can directly repress the PAI-1 gene. DNase I hypersensitive-site analysis of the PAI-1 promoter suggested the involvement of conformation changes in chromatin structure of the PAI-1 promoter. 5' deletion analysis of the PAI-1 promoter showed that multiple sites were responsible for the E2F negative regulation, some of which were promoter dependent. Interestingly, one of these sites is a p53-binding element.
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PMID:E2F1-mediated transcriptional inhibition of the plasminogen activator inhibitor type 1 gene. 1155 66