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)

In Saccharomyces cerevisiae, the CDC2 gene encodes the large subunit of DNA polymerase III, the analogue of mammalian DNA polymerase delta. We have isolated DNA fragments from a library of Candida albicans genomic DNA in the vector pRS316 that rescue temperature sensitive cdc2 mutations in S. cerevisiae. These fragments contain an ORF coding for a protein of 1038 aa with a predicted molecular mass of 118.8 kDa. The predicted protein shows homology to a number of eukaryotic DNA polymerases, with 62% identity over its length to the S. cerevisiae Cdc2 protein. It also contains a number of motifs which are characteristic of DNA polymerases in general and viral polymerases in particular, as well as the conserved motif which interacts with proliferating cell nuclear antigen. These results indicate that this gene is C. albicans POL3. Analysis of the expression of C. albicans POL3 revealed that the transcript is present throughout the mitotic cell cycle, which contrasts with the expression of S. cerevisiae CDC2.
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PMID:Isolation and molecular characterisation of the POL3 gene from Candida albicans. 899 2

The E8 open reading frame of Bovine papillomavirus type 4 (BPV-4) encodes a small (42 amino acid) hydrophobic polypeptide localized to cellular membranes and capable of conferring an anchorage-independent (AI) growth phenotype on primary bovine cells co-transfected with BPV-4 E7 ORF and an activated ras gene. To further study the function of E8 independently of other viral gene products, we have expressed it in the murine fibroblast cell line, NIH3T3. Cells expressing E8 are capable of AI growth and escape growth arrest after serum withdrawal. E8 deregulates cyclin A expression, induces transactivation of the human cyclin A gene promoter and increases endogenous protein levels in cells maintained in short-term suspension culture and in low-serum (LS). Both these culture conditions promote downregulation of cyclin A in control cells. In LS growth conditions E8 permits sustained cyclin A-associated kinase activity but not cyclin E-cdk2 activity. Cyclin A-cdk2 activity and, in part, cyclin A gene expression are regulated by the cdk inhibitor p27Kip1. Expression of this cdk inhibitor is also de-regulated in E8 cells, with high levels being detected under all culture conditions tested. These data suggest that the ability of BPV-4 E8 to transform NIH3T3 cells is associated with upregulation of cyclin A-associated kinase activity and de-regulated expression of the cdk inhibitor p27Kip1 and does not rely on down-regulation of p27Kip1 expression. Analysis of E8 mutants indicate that the hydrophilic 'tail' of the molecule (residues 31-42) is required for cell transformation, as assessed by anchorage-independent growth, while a form of E8 with expression restricted to the Endoplasmic Reticulum/cis-Golgi membranes by addition of a 'KDEL' retention signal revealed that the sub-cellular localization is an important determinant of E8 biological activity.
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PMID:BPV-4 E8 transforms NIH3T3 cells, up-regulates cyclin A and cyclin A-associated kinase activity and de-regulates expression of the cdk inhibitor p27Kip1. 969 May 11

Mammalian Cdc25 phosphatase is responsible for the dephosphorylation of Cdc2 and other cyclin-dependent kinases at Thr14 and Tyr15, thus activating the kinase and allowing cell cycle progression. The catalytic domain of this dual-specificity phosphatase has recently been mapped to the 180 most C-terminal amino acids. Apart from a CX3R motif, which is present at the active site of all known tyrosine phosphatases, Cdc25 does not share any obvious sequence similarity with any of those enzymes. Until very recently, the Cdc25 family was the only subfamily of tyrosine phosphates for which no three-dimensional structural data were available. Using the generalized profile technique, a sensitive method for sequence database searches, we found an extended and highly significant sequence similarity between the Cdc25 catalytic domain and similarly sized regions in other proteins: the non-catalytic domain of two distinct families of MAP-kinase phosphates, the non-catalytic domain of several ubiquitin protein hydrolases, the N and C-terminal domain of rhodanese, and a large and heterogeneous groups of stress-response proteins from all phyla. The relationship of Cdc25 to the structurally well-characterized rhodanese spans the entire catalytic domain and served as template for a structural model for human Cdc25a, which is fundamentally different from previously suggested models for Cdc25 catalytic domain organization. The surface positioning of subfamily-specific conserved residues allows us to predict the sites of interaction with Cdk2, a physiological target of Cdc25a. Based on the results of this analysis, we also predict that the budding yeast arsenate resistance protein Acr2 and the ORF Ygr203w encode protein phosphatases with catalytic properties similar to that of the Cdc25 family. Recent determination of the crystal structure of the Cdc25a catalytic domain supports the validity of the model and demonstrates the power of the generalized sequence profile technique in homology-based modeling of the three-dimensional structure of a protein having a weak but significant sequence similarity with a structurally characterized protein.
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PMID:A model of Cdc25 phosphatase catalytic domain and Cdk-interaction surface based on the presence of a rhodanese homology domain. 973 50

p27(Kip1) regulates cell proliferation by binding to and modulating the activity of cyclin-dependent kinases. The CDK inhibitor is haploinsufficient for tumor suppression and reduced p27 activity is fundamental for the development of many human malignancies. Consistently, reduced p27 protein provides independent prognostic information in various tumors including breast, prostate, colon and gastric carcinomas. In normal cells, p27 protein increases in growth arrest but also oscillates during cell cycle progression. Expression of p27 is regulated through mechanisms including transcription, translation and ubiquitin-mediated degradation. Each of these pathways may contribute to deregulation of p27 in hyperproliferative diseases. p27 translation increases in proliferating cells during G(1) phase and declines as cells enter S phase. To investigate the mechanisms of p27 translational control, we analyzed fragments of the p27 transcript for their contribution to cell cycle regulated translation. We found that an element in the p27 5'-UTR can render reporter translation cell cycle sensitive with maximal translation in G1-arrested cells. This novel element of 114 nt contains a G/C-rich hairpin domain that is predicted to form multiple stable stemloops and also overlaps with a small upstream ORF (uORF). Both structures contribute to cell cycle-regulated translation. The uORF can be translated in vitro and its sequence and position are highly conserved in mice and chickens. Interestingly, the precise sequence or the length of the uORF-encoded peptide are not important for p27 translation, consistent with the idea that ribosomal recruitment to its initiation codon rather than the translation product itself contributes to the regulation.
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PMID:Cell cycle-dependent translation of p27 involves a responsive element in its 5'-UTR that overlaps with a uORF. 1283 99

Kaposi sarcoma (KS) remains the most common AIDS-associated malignancy worldwide. In sub-Saharan Africa especially, this aggressive endothelial-cell tumor is a cause of widespread morbidity and mortality. Infection with Kaposi sarcoma-associated herpesvirus (KSHV) is now known to be an etiologic force behind KS and primary-effusion lymphoma (PEL). Over time, KSHV has pirated many human genes whose products regulate angiogenesis, inflammation, and the cell cycle. One of these, the KSHV vGPCR, is a lytic product that is a constitutively active homolog of the IL-8 receptor. Although it is considered a viral oncogene and causes KS-like lesions in mice, vGPCR expression results in cell-cycle arrest of KSHV-infected PEL cells. In the present study, we show that this arrest is mediated by p21 in a p53-independent manner; the resulting Cdk2 inhibition decreases the efficiency of chemical induction of KSHV lytic transcripts ORF 50 and 26. Importantly, Cdk2 activity is also essential for replication in other human herpesviruses. The ability of vGPCR to delay or abort KSHV replication may explain how despite being a lytic product, this potent signaling molecule has a vital role in tumor formation via its induction of various KS-associated cytokines.
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PMID:KSHV G protein-coupled receptor inhibits lytic gene transcription in primary-effusion lymphoma cells via p21-mediated inhibition of Cdk2. 1615 Sep 42

The G2/M arrest function of human papillomavirus (HPV) E4 proteins is hypothesized to be necessary for viral genome amplification. Full-length HPV18 E1^E4 protein is essential for efficient viral genome amplification. Here we identify key determinants within a CDK-bipartite consensus recognition motif in HPV18 E1^E4 that are critical for association with active CDK-cyclin complexes and in vitro phosphorylation at the predicted CDK phosphorylation site (threonine 23). The optimal cyclin-binding sequence ((43)RRLL(46)) within this E4 motif is required for G2/M arrest of primary keratinocytes and correlates with cytoplasmic retention of cyclin B1, but not cyclin A. Disruption of this motif in the E4 ORF of HPV18 genomes, and the subsequent generation of stable cell lines in primary keratinocytes revealed that this motif was not essential for viral genome amplification or L1 capsid protein induction. We conclude that the HPV18 E4 G2/M arrest function does not play a role in early vegetative events.
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PMID:A cyclin-binding motif in human papillomavirus type 18 (HPV18) E1^E4 is necessary for association with CDK-cyclin complexes and G2/M cell cycle arrest of keratinocytes, but is not required for differentiation-dependent viral genome amplification or L1 capsid protein expression. 2127 99

Combinatorial inhibition of MEK1/2 and CDK4/6 is currently undergoing clinical investigation in NRAS-mutant melanoma. To prospectively map the landscape of resistance to this investigational regimen, we utilized a series of gain- and loss-of-function forward genetic screens to identify modulators of resistance to clinical inhibitors of MEK1/2 and CDK4/6 alone and in combination. First, we identified NRAS-mutant melanoma cell lines that were dependent on NRAS for proliferation and sensitive to MEK1/2 and CDK4/6 combination treatment. We then used a genome-scale ORF overexpression screen and a CRISPR knockout screen to identify modulators of resistance to each inhibitor alone or in combination. These orthogonal screening approaches revealed concordant means of achieving resistance to this therapeutic modality, including tyrosine kinases, RAF, RAS, AKT, and PI3K signaling. Activated KRAS was sufficient to cause resistance to combined MEK/CDK inhibition and to replace genetic depletion of oncogenic NRAS. In summary, our comprehensive functional genetic screening approach revealed modulation of resistance to the inhibition of MEK1/2, CDK4/6, or their combination in NRAS-mutant melanoma. SIGNIFICANCE: These findings reveal that NRAS-mutant melanomas can acquire resistance to genetic ablation of NRAS or combination MEK1/2 and CDK4/6 inhibition by upregulating activity of the RTK-RAS-RAF and RTK-PI3K-AKT signaling cascade.
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PMID:A Functional Landscape of Resistance to MEK1/2 and CDK4/6 Inhibition in NRAS-Mutant Melanoma. 3081 66