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)

In a screen for second site mutations capable of reducing the restrictive temperature of the fission yeast mutant cdc2-D217N, we have isolated a novel temperature-sensitive mutant, dim1-35. When shifted to restrictive temperature, dim1-35 mutant cells arrest before entry into mitosis or proceed through mitosis in the absence of nuclear division, demonstrating an uncoupling of proper DNA segregation from other cell cycle events. Deletion of dim1 from the Schizosaccharomyces pombe genome produces a lethal G2 arrest phenotype. Lethality is rescued by overexpression of the mouse dim1 homolog, mdim1. Likewise, deletion of the Saccharomyces cerevisiae dim1 homolog, CDH1, is lethal. Both mdim1 and dim1(+) are capable of rescuing lethality in the cdh1::HIS3 mutant. Although dim1-35 displays no striking genetic interactions with various other G2/M or mitotic mutants, dim1-35 cells incubated at restrictive temperature arrest with low histone H1 kinase activity. Morevoer, dim1-35 displays sensitivity to the microtubule destabilizing drug, thiabendazole (TBZ). We conclude that Dim1p plays a fundamental, evolutionarily conserved role as a protein essential for entry into mitosis as well as for chromosome segregation during mitosis. Based on TBZ sensitivity and failed chromosome segregation in dim1-35, we further speculate that Dim1p may play a role in mitotic spindle formation and/or function.
 ...
PMID:Fission yeast dim1(+) encodes a functionally conserved polypeptide essential for mitosis. 918 66

Ubiquitination and subsequent degradation of critical cell cycle regulators is a key mechanism exploited by the cell to ensure an irreversible progression of cell cycle events. The anaphase-promoting complex (APC) is a ubiquitin ligase that targets proteins for degradation by the 26S proteasome. Here we identify the Hsl1p protein kinase as an APC substrate that interacts with Cdc20p and Cdh1p, proteins that mediate APC ubiquitination of protein substrates. Hsl1p is absent in G(1), accumulates as cells begin to bud, and disappears in late mitosis. Hsl1p is stabilized by mutations in CDH1 and CDC23, both of which result in compromised APC activity. Unlike Hsl1p, Gin4p and Kcc4p, protein kinases that have sequence homology to Hsl1p, were stable in G(1)-arrested cells containing active APC. Mutation of a destruction box motif within Hsl1p (Hsl1p(db-mut)) stabilized Hsl1p. Interestingly, this mutation also disrupted the Hsl1p-Cdc20p interaction and reduced the association between Hsl1p and Cdh1p in coimmunoprecipitation studies. These findings suggest that the destruction box motif is required for Cdc20p and, to a lesser extent, for Cdh1p to target Hsl1p to the APC for ubiquitination. Hsl1p has been previously shown to inhibit Swe1p, a protein kinase that negatively regulates the cyclin-dependent kinase Cdc28p, by promoting Swe1p degradation via SCF(Met30) in a bud morphogenesis checkpoint. Results of the present work indicate that Hsl1p is degraded in an APC-dependent manner and suggest a link between the SCF (Skp1-cullin-F box) and APC-proteolytic systems that may help to coordinate the proper progression of cell cycle events.
 ...
PMID:Hsl1p, a Swe1p inhibitor, is degraded via the anaphase-promoting complex. 1084 88

CDC6 is conserved during evolution and is essential and limiting for the initiation of eukaryotic DNA replication. Human CDC6 activity is regulated by periodic transcription and CDK-regulated subcellular localization. Here, we show that, in addition to being absent from nonproliferating cells, CDC6 is targeted for ubiquitin-mediated proteolysis by the anaphase promoting complex (APC)/cyclosome in G(1). A combination of point mutations in the destruction box and KEN-box motifs in CDC6 stabilizes the protein in G(1) and in quiescent cells. Furthermore, APC, in association with CDH1, ubiquitinates CDC6 in vitro, and both APC and CDH1 are required and limiting for CDC6 proteolysis in vivo. Although a stable mutant of CDC6 is biologically active, overexpression of this mutant or wild-type CDC6 is not sufficient to induce multiple rounds of DNA replication in the same cell cycle. The APC-CDH1-dependent proteolysis of CDC6 in early G(1) and in quiescent cells suggests that this process is part of a mechanism that ensures the timely licensing of replication origins during G(1).
 ...
PMID:Cell cycle- and cell growth-regulated proteolysis of mammalian CDC6 is dependent on APC-CDH1. 1099 89

Cdh1p, a substrate specificity factor for the cell cycle-regulated ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C), promotes exit from mitosis by directing the degradation of a number of proteins, including the mitotic cyclins. Here we present evidence that Cdh1p activity at the M/G(1) transition is important not only for mitotic exit but also for high-fidelity chromosome segregation in the subsequent cell cycle. CDH1 showed genetic interactions with MAD2 and PDS1, genes encoding components of the mitotic spindle assembly checkpoint that acts at metaphase to prevent premature chromosome segregation. Unlike cdh1delta and mad2delta single mutants, the mad2delta cdh1delta double mutant grew slowly and exhibited high rates of chromosome and plasmid loss. Simultaneous deletion of PDS1 and CDH1 caused extensive chromosome missegregation and cell death. Our data suggest that at least part of the chromosome loss can be attributed to kinetochore/spindle problems. Our data further suggest that Cdh1p and Sic1p, a Cdc28p/Clb inhibitor, have overlapping as well as nonoverlapping roles in ensuring proper chromosome segregation. The severe growth defects of both mad2delta cdh1delta and pds1delta cdh1dDelta strains were rescued by overexpressing Swe1p, a G(2)/M inhibitor of the cyclin-dependent kinase, Cdc28p/Clb. We propose that the failure to degrade cyclins at the end of mitosis leaves cdh1delta mutant strains with abnormal Cdc28p/Clb activity that interferes with proper chromosome segregation.
 ...
PMID:The role of Cdh1p in maintaining genomic stability in budding yeast. 1457 64

Gastrointestinal stromal tumors (GIST) are caused by activating mutations in the KIT or platelet-derived growth factor receptor alpha receptor tyrosine kinase genes. Approximately 85% of GIST patients treated with imatinib mesylate achieve disease stabilization, however, often in the presence of residual tumor masses. Complete remissions are rare and a substantial proportion of patients develop resistance to imatinib. Our study was designed to determine whether imatinib-associated responses may account for these clinical findings. We report here that imatinib stimulates cellular quiescence in a proportion of GIST cells as evidenced by up-regulation of the CDK inhibitor p27(Kip1), loss of cyclin A, and reduced BrdUrd incorporation. Mechanistically, these events are associated with an imatinib-induced modulation of the APC/CDH1 signaling axis. Specifically, we provide evidence that imatinib down-regulates SKP2 and that this event is associated with increased nuclear CDH1, an activator of the APC that has been shown to regulate SKP2 stability. We also show that those GIST cells that do not undergo apoptosis in response to imatinib overexpress nuclear p27(Kip1), indicating that they have withdrawn from the cell cycle and are quiescent. Lastly, we provide evidence that a fraction of primary GISTs with high SKP2 expression levels may have an increased risk of disease progression. Taken together, our results support a model in which GIST cells that do not respond to imatinib by apoptosis are removed from the proliferative pool by entering quiescence through modulation of the APC/CDH1-SKP2-p27(Kip1) signaling axis. These results encourage further studies to explore compounds that modulate this pathway as antitumor agents in GISTs.
 ...
PMID:Imatinib mesylate induces quiescence in gastrointestinal stromal tumor cells through the CDH1-SKP2-p27Kip1 signaling axis. 1897 47

Absent in melanoma 2 (AIM2) is a member of the interferon-inducible HIN-200 protein family. Recent findings point to a role of AIM2 function in both inflammation and cancer. In response to foreign cytoplasmic DNA, AIM2 forms an inflammasome, resulting in caspase activation in inflammatory cells. Moreover, AIM2 reduces breast cancer cell proliferation and mammary tumor growth in a mouse model and shows a high frequency of frameshift mutations in microsatellite unstable (MSI-H) gastric, endometrial and colorectal cancers. However, the consequences of AIM2 restoration in AIM2-deficient colon cancer cells have not yet been examined. Using different constructs for expression of AIM2 fusion proteins, we found that AIM2 restoration clearly suppressed cell proliferation and viability in HCT116 cells as well as in cell lines derived from other entities. In contrast to previous reports from breast cancer cells, our cell cycle analyses of colon cancer cells revealed that AIM2-mediated inhibition of cell proliferation is associated with accumulation of cells at late S-phase, resulting in G2/M arrest. The latter correlated well with upregulation of cyclin D3 and p21(Waf1/Cip1) as well as with inhibition of cdc2 activity through Tyr-15 phosphorylation. Furthermore, AIM2 restoration affected the adhesion of colorectal cancer cells to fibronectin and stimulated the invasion through extracellular matrix-coated membrane in transwell assays. Consistent with this phenotype, AIM2 induced the expression of invasion-associated genes such as VIM and MCAM, whereas ANXA10 and CDH1 were downregulated. Our data suggest that AIM2 mediates reduction of cell proliferation by cell cycle arrest, thereby conferring an invasive phenotype in colon cancer cells.
 ...
PMID:Restoration of absent in melanoma 2 (AIM2) induces G2/M cell cycle arrest and promotes invasion of colorectal cancer cells. 1979 19

MicroRNAs (miRNAs) control cell cycle progression by targeting the transcripts encoding for cyclins, CDKs and CDK inhibitors, such as p27(KIP1) (p27). p27 expression is controlled by multiple transcriptional and posttranscriptional mechanisms, including translational inhibition by miR-221/222 and posttranslational regulation by the SCF(SKP2) complex. The oncosuppressor activity of miR-340 has been recently characterized in breast, colorectal and osteosarcoma tumor cells. However, the mechanisms underlying miR-340-induced cell growth arrest have not been elucidated. Here, we describe miR-340 as a novel tumor suppressor in non-small cell lung cancer (NSCLC). Starting from the observation that the growth-inhibitory and proapoptotic effects of miR-340 correlate with the accumulation of p27 in lung adenocarcinoma and glioblastoma cells, we have analyzed the functional relationship between miR-340 and p27 expression. miR-340 targets three key negative regulators of p27. The miR-340-mediated inhibition of both Pumilio family RNA-binding proteins (PUM1 and PUM2), required for the miR-221/222 interaction with the p27 3'-UTR, antagonizes the miRNA-dependent downregulation of p27. At the same time, miR-340 induces the stabilization of p27 by targeting SKP2, the key posttranslational regulator of p27. Therefore, miR-340 controls p27 at both translational and posttranslational levels. Accordingly, the inhibition of either PUM1 or SKP2 partially recapitulates the miR-340 effect on cell proliferation and apoptosis. In addition to the effect on tumor cell proliferation, miR-340 also inhibits intercellular adhesion and motility in lung cancer cells. These changes correlate with the miR-340-mediated inhibition of previously validated (MET and ROCK1) and potentially novel (RHOA and CDH1) miR-340 target transcripts. Finally, we show that in a small cohort of NSCLC patients (n=23), representative of all four stages of lung cancer, miR-340 expression inversely correlates with clinical staging, thus suggesting that miR-340 downregulation contributes to the disease progression.
...
PMID:miR-340 inhibits tumor cell proliferation and induces apoptosis by targeting multiple negative regulators of p27 in non-small cell lung cancer. 2515 66

FZR1/CDH1 is an activator of Anaphase promoting complex/Cyclosome (APC/C), best known for its role as E3 ubiquitin ligase that drives the cell cycle. APC/C activity is regulated by CDK-mediated phosphorylation of FZR1 during mitotic cell cycle. Although the critical role of FZR1 phosphorylation has been shown mainly in yeast and in vitro cell culture studies, its biological significance in mammalian tissues in vivo remained elusive. Here, we examined the in vivo role of FZR1 phosphorylation using a mouse model, in which non-phosphorylatable substitutions were introduced in the putative CDK-phosphorylation sites of FZR1. Although ablation of FZR1 phosphorylation did not show substantial consequences in mouse somatic tissues, it led to severe testicular defects resulting in male infertility. In the absence of FZR1 phosphorylation, male juvenile germ cells entered meiosis normally but failed to enter meiosis II or form differentiated spermatids. In aged testis, male mutant germ cells were overall abolished, showing Sertoli cell-only phenotype. In contrast, female mutants showed apparently normal progression of meiosis. The present study demonstrated that phosphorylation of FZR1 is required for temporal regulation of APC/C activity at meiosis II entry, and for maintenance of spermatogonia, which raised an insight into the sexual dimorphism of FZR1-regulation in germ cells.
 ...
PMID:Phosphorylation of the Anaphase Promoting Complex activator FZR1/CDH1 is required for Meiosis II entry in mouse male germ cell. 3257 94