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Yoon S, Kawasaki I, Shim YH. CDC-25.1 controls the rate of germline mitotic cell cycle by counteracting WEE-1.3 and by positively regulating CDK-1 in Caenorhabditis elegans. Cell Cycle 2012; 11:1354-63. [PMID: 22421141 DOI: 10.4161/cc.19755] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In Caenorhabditis elegans, cdc-25.1 loss-of-function mutants display a lack of germline proliferation. We found that the proliferation defect of cdc-25.1 mutants was suppressed by wee-1.3 RNAi. Further, among the seven cdk and seven cyclin homologs examined, cdk-1 and cyb-3 RNAi treatment caused the most severe germline proliferation defects in an rrf-1 mutant background, which were similar to those of the cdc-25.1 mutants. In addition, while RNAi of cyd-1 and cye-1 caused significant germline proliferation defects, RNAi of cdk-2 and cdk-4 did not. Compared with the number of germ nuclei in wee-1.3(RNAi) worms, the number in wee-1.3(RNAi);cdk-1(RNAi) and wee-1.3(RNAi);cyb-3(RNAi) worms further decreased to the level of cdk-1(RNAi) and cyb-3(RNAi) worms, respectively, indicating that cdk-1 and cyb-3 are epistatic and function downstream of cdc-25.1 and wee-1.3 in the control of the cell cycle. BrdU labeling of adult worms showed that, while 100% of the wild-type germ nuclei in the mitotic region incorporated BrdU when labeled for more than 12 h at 20°C, a small fraction of the cdc-25.1 mutant germ nuclei failed to incorporate BrdU even when labeled for 68 h. These results indicate that CDC-25.1 is required for maintaining proper rate of germline mitotic cell cycle. We propose that CDC-25.1 regulates the rate of germline mitotic cell cycle by counteracting WEE-1.3 and by positively controlling CDK-1, which forms a complex primarily with CYB-3, but also possibly with CYD-1 and CYE-1.
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Affiliation(s)
- Sunghee Yoon
- Department of Bioscience and Biotechnology, Institute of Functional Genomics, Konkuk University, Seoul, South Korea
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Abstract
A new dammarane-type triterpene saponin was isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino. Its structural elucidation was accomplished mainly on the basis of the interpretation of spectroscopic data, such as IR, HR-TOF-MS and NMR. Its cytotoxic activity was evaluated against one human cancer cell line HL-60 using MTT assay.
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Affiliation(s)
- Lin Shi
- College of Food Science, Shenyang Agriculture University, Shenyang 110866, China
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53
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Baldi A, De Luca A, Esposito V, Campioni M, Spugnini EP, Citro G. Tumor suppressors and cell-cycle proteins in lung cancer. PATHOLOGY RESEARCH INTERNATIONAL 2011; 2011:605042. [PMID: 22007345 PMCID: PMC3189597 DOI: 10.4061/2011/605042] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 08/08/2011] [Indexed: 11/20/2022]
Abstract
The cell cycle is the cascade of events that allows a growing cell to duplicate all its components and split into two daughter cells. Cell cycle progression is mediated by the activation of a highly conserved family of protein kinases, the cyclin-dependent kinases (CDKs). CDKs are also regulated by related proteins called cdk inhibitors grouped into two families: the INK4 inhibitors (p16, p15, p19, and p18) and the Cip/Kip inhibitors (p21, p27, and p53). Several studies report the importance of cell-cycle proteins in the pathogenesis and the prognosis of lung cancer. This paper will review the most recent data from the literature about the regulation of cell cycle. Finally, based essentially on the data generated in our laboratory, the expression, the diagnostic, and prognostic significance of cell-cycle molecules in lung cancer will be examined.
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Affiliation(s)
- Alfonso Baldi
- Section of Pathology, Department of Biochemistry, Second University of Naples, 80138 Naples, Italy
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Shao FG, Bu R, Zhang C, Chen CJ, Huang J, Wang JH. Two new casbane diterpenoids from the roots of Euphorbia pekinensis. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2011; 13:805-10. [PMID: 21830884 DOI: 10.1080/10286020.2011.596828] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
From the roots of Euphorbia pekinensis, two new casbane diterpenoids, named pekinenins A (1) and B (2), were isolated. Their structures were elucidated as 18-hydroxy-1βH,2αH-casba-3E,7E,11E-trien-5-one (1), 5α-methoxy-1βH,2αH-casba-3Z,7E,11E-trien-18-oic acid (2) by a combination of 1D and 2D NMR spectroscopy and mass spectrometry. In the cytotoxicity assay of the two new compounds against Hela, MCF-7, and C6 human cancer cell lines, compound 1 showed moderate cytotoxic activity against two human cancer cell lines, Hela and C6, with IC(50) values of 42.97 and 50.00 μM, respectively.
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Affiliation(s)
- Feng-Guang Shao
- School of Traditional Chinese Materia Medica 49#, Shenyang Pharmaceutical University, Shenyang 110016, China
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55
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Chen XL, Liu HL, Li J, Xin GR, Guo YW. Paracaseolide A, First α-Alkylbutenolide Dimer with an Unusual Tetraquinane Oxa-Cage Bislactone Skeleton from Chinese Mangrove Sonneratia paracaseolaris. Org Lett 2011; 13:5032-5. [PMID: 21875121 DOI: 10.1021/ol201809q] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xue-Lian Chen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zhi Road, 555, Shanghai 201203, China, and Institute of Biological Science, Sun Yat-Sen University, Xin Gang West Road 135, Guangzhou 510275, China
| | - Hai-Li Liu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zhi Road, 555, Shanghai 201203, China, and Institute of Biological Science, Sun Yat-Sen University, Xin Gang West Road 135, Guangzhou 510275, China
| | - Jia Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zhi Road, 555, Shanghai 201203, China, and Institute of Biological Science, Sun Yat-Sen University, Xin Gang West Road 135, Guangzhou 510275, China
| | - Guo-Rong Xin
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zhi Road, 555, Shanghai 201203, China, and Institute of Biological Science, Sun Yat-Sen University, Xin Gang West Road 135, Guangzhou 510275, China
| | - Yue-Wei Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zu Chong Zhi Road, 555, Shanghai 201203, China, and Institute of Biological Science, Sun Yat-Sen University, Xin Gang West Road 135, Guangzhou 510275, China
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Abstract
There is increasing evidence to show that 2-cell stage mouse blastomeres have differing developmental properties. Additionally, it has been suggested that such a difference might be due to their distribution of mRNA and/or protein asymmetry. However, to date, the exact genes that are involved in the orientation and order of blastomere division are not known. In this study, some differentially expressed transcripts were identified. Axin1, cell division cycle 25 homolog C (Cdc25c) and cyclin-dependent inhibitor 2D (Cdkn2d) were selected for validation by real-time polymerase chain reaction (PCR) based on published data. Our real-time PCR results demonstrated that Axin1, Cdc25c and Cdkn2d genes had different levels of expression among blastomeres of the mouse 2-cell embryo i.e. the level of Axin1 mRNA was significantly higher in one blastomere when compared with the other blastomeres of the 2-cell embryo (p < 0.05). The variation in Cdc25c (p < 0.05) and Cdkn2d (p < 0.01) mRNA expression followed a similar trend to that of Axin1. In addition, the highest levels of expression of these three genes were detected in the same blastomere in the 2-cell embryo. We confirmed that there was an asymmetrical distribution pattern for Axin1, Cdc25c and Cdkn2d transcripts in 2-cell embryos. In conclusion, this study demonstrated clearly that there is embryonic asymmetry at the 2-cell stage and that these differentially expressed genes may result in differentiation in expression in embryo development.
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Albert H, Santos S, Battaglia E, Brito M, Monteiro C, Bagrel D. Differential expression of CDC25 phosphatases splice variants in human breast cancer cells. Clin Chem Lab Med 2011; 49:1707-14. [PMID: 21675940 DOI: 10.1515/cclm.2011.635] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND CDC25 phosphatases control cell cycle progression by activating cyclin dependent kinases. The three CDC25 isoforms encoding genes are submitted to alternative splicing events which generate at least two variants for CDC25A and five for both CDC25B and CDC25C. An over-expression of CDC25 was reported in several types of cancer, including breast cancer, and is often associated with a poor prognosis. Nevertheless, most of the previous studies did not address the expression of CDC25 splice variants. Here, we evaluated CDC25 spliced transcripts expression in anti-cancerous drug-sensitive and resistant breast cancer cell lines in order to identify potential breast cancer biomarkers. METHODS CDC25 splice variants mRNA levels were evaluated by semi-quantitative RT-PCR and by an original real-time RT-PCR assay. RESULTS CDC25 spliced transcripts are differentially expressed in the breast cancer cell lines studied. An up-regulation of CDC25A2 variant and an increase of the CDC25C5/C1 ratio are associated to the multidrug-resistance in VCREMS and DOXOR breast cancer cells, compared to their sensitive counterpart cell line MCF-7. Additionally, CDC25B2 transcript is exclusively over-expressed in VCREMS resistant cells and could therefore be involved in the development of certain type of drug resistance. CONCLUSIONS CDC25 splice variants could represent interesting potential breast cancer prognostic biomarkers.
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Affiliation(s)
- Hélène Albert
- Laboratoire d'Ingénierie Moléculaire et Biochimie Pharmacologique, EA 3940, FR CNRS 2843, Université Paul Verlaine-Metz, Metz, France
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58
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Chiu SC, Wang MJ, Yang HH, Chen SP, Huang SY, Chen YL, Lin SZ, Harn HJ, Pang CY. Activation of NAG-1 via JNK signaling revealed an isochaihulactone-triggered cell death in human LNCaP prostate cancer cells. BMC Cancer 2011; 11:146. [PMID: 21504622 PMCID: PMC3095567 DOI: 10.1186/1471-2407-11-146] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 04/20/2011] [Indexed: 01/05/2023] Open
Abstract
Background We explored the mechanisms of cell death induced by isochaihulactone treatment in LNCaP cells. Methods LNCaP cells were treated with isochaihulactone and growth inhibition was assessed. Cell cycle profiles after isochaihulactone treatment were determined by flow cytometry. Expression levels of cell cycle regulatory proteins, caspase 9, caspase 3, and PARP were determined after isochaihulactone treatment. Signaling pathway was verified by inhibitors pre-treatment. Expression levels of early growth response gene 1 (EGR-1) and nonsteroidal anti-inflammatory drug-activated gene 1 (NAG-1) were determined to investigate their role in LNCaP cell death. NAG-1 expression was knocked down by si-NAG-1 siRNA transfection. Rate of cell death and proliferation were obtained by MTT assay. Results Isochaihulactone caused cell cycle arrest at G2/M phase in LNCaP cells, which was correlated with an increase of p53 and p21 levels and downregulation of the checkpoint proteins cdc25c, cyclin B1, and cdc2. Bcl-2 phosphorylation and caspase activation were also observed. Isochaihulactone induced phosphorylation of c-Jun-N-terminal kinase (JNK), and JNK inhibitor partially reduced isochaihulactone-induced cell death. Isochaihulactone also induced the expressions of EGR-1 and NAG-1. Expression of NAG-1 was reduced by JNK inhibitor, and knocking down of NAG-1 inhibited isochaihulactone-induced cell death. Conclusions Isochaihulactone apparently induces G2/M cell cycle arrest via downregulation of cyclin B1 and cdc2, and induces cellular death by upregulation of NAG-1 via JNK activation in LNCaP cells.
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Affiliation(s)
- Sheng-Chun Chiu
- Institute of Medical Sciences, Tzu-Chi University, and Department of Medical Research, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan
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Human Cdc14B promotes progression through mitosis by dephosphorylating Cdc25 and regulating Cdk1/cyclin B activity. PLoS One 2011; 6:e14711. [PMID: 21379580 PMCID: PMC3040744 DOI: 10.1371/journal.pone.0014711] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 01/23/2011] [Indexed: 12/18/2022] Open
Abstract
Entry into and progression through mitosis depends on phosphorylation and dephosphorylation of key substrates. In yeast, the nucleolar phosphatase Cdc14 is pivotal for exit from mitosis counteracting Cdk1-dependent phosphorylations. Whether hCdc14B, the human homolog of yeast Cdc14, plays a similar function in mitosis is not yet known. Here we show that hCdc14B serves a critical role in regulating progression through mitosis, which is distinct from hCdc14A. Unscheduled overexpression of hCdc14B delays activation of two master regulators of mitosis, Cdc25 and Cdk1, and slows down entry into mitosis. Depletion of hCdc14B by RNAi prevents timely inactivation of Cdk1/cyclin B and dephosphorylation of Cdc25, leading to severe mitotic defects, such as delay of metaphase/anaphase transition, lagging chromosomes, multipolar spindles and binucleation. The results demonstrate that hCdc14B-dependent modulation of Cdc25 phosphatase and Cdk1/cyclin B activity is tightly linked to correct chromosome segregation and bipolar spindle formation, processes that are required for proper progression through mitosis and maintenance of genomic stability.
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60
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Shi L, Cao JQ, Shi SM, Zhao YQ. Triterpenoid saponins from Gynostemma pentaphyllum. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2011; 13:168-77. [PMID: 21279881 DOI: 10.1080/10286020.2010.547029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Four new dammarane-type triterpene saponins, 1-4, were isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino. Their structural elucidations were accomplished mainly on the basis of spectroscopic methods, such as IR, HR-TOF-MS, and NMR. Compounds 1-4 showed moderate cytotoxic activities against cancer cell lines HL-60, Colon205, and Du145 in vitro.
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Affiliation(s)
- Lin Shi
- College of Food Science, Shenyang Agriculture University, Shenyang, China
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61
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Xiao J, Liu C, Hou J, Cui C, Wu D, Fan H, Sun X, Meng J, Yang F, Wang E, Yu B. Ser149 is another potential PKA phosphorylation target of Cdc25B in G2/M transition of fertilized mouse eggs. J Biol Chem 2011; 286:10356-66. [PMID: 21212267 DOI: 10.1074/jbc.m110.150524] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It is well documented that protein kinase A (PKA) acts as a negative regulator of M phase promoting factor (MPF) by phosphorylating cell division cycle 25 homolog B (Cdc25B) in mammals. However, the molecular mechanism remains unclear. In this study, we identified PKA phosphorylation sites in vitro by LC-MS/MS analysis, including Ser(149), Ser(229), and Ser(321) of Cdc25B, and explored the role of Ser(149) in G(2)/M transition of fertilized mouse eggs. The results showed that the overexpressed Cdc25B-S149A mutant initiated efficient MPF activation by direct dephosphorylation of Cdc2-Tyr(15), resulting in triggering mitosis prior to Cdc25B-WT. Conversely, overexpression of the phosphomimic Cdc25B-S149D mutant showed no significant difference in comparison with the control groups. Furthermore, we found that Cdc25B-Ser(149) was phosphorylated at G(1) and S phases, whereas dephosphorylated at G(2) and M phases, and the phosphorylation of Cdc25B-Ser(149) was modulated by PKA in vivo. In addition, we examined endogenous and exogenous Cdc25B, which were expressed mostly in the cytoplasm at the G(1) and S phases and translocated to the nucleus at the G(2) phase. Collectively, our findings provide evidence that Ser(149) may be another potential PKA phosphorylation target of Cdc25B in G(2)/M transition of fertilized mouse eggs and Cdc25B as a direct downstream substrate of PKA in mammals, which plays important roles in the regulation of early development of mouse embryos.
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Affiliation(s)
- Jianying Xiao
- Institute of Pathology and Pathopysiology, China Medical University, Shenyang, Liaoning Province 110001, China
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Schindler K. Protein kinases and protein phosphatases that regulate meiotic maturation in mouse oocytes. Results Probl Cell Differ 2011; 53:309-341. [PMID: 21630151 DOI: 10.1007/978-3-642-19065-0_14] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Oocytes arrest at prophase of meiosis I (MI) and in vivo do not resume meiosis until they receive ovulatory cues. Meiotic resumption entails two rounds of chromosome segregation without an intervening round of DNA replication and an arrest at metaphase of meiosis II (MII); fertilization triggers exit from MII and entry into interphase. During meiotic resumption, there is a burst of protein phosphorylation and dephosphorylation that dramatically changes during the course of oocyte meiotic maturation. Many of these phosphorylation and dephosphorylation events are key to regulating meiotic cell cycle arrest and/or progression, chromosome dynamics, and meiotic spindle assembly and disassembly. This review, which is subdivided into sections based upon meiotic cell cycle stages, focuses on the major protein kinases and phosphatases that have defined requirements during meiosis in mouse oocytes and, when possible, connects these regulatory pathways.
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Affiliation(s)
- Karen Schindler
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, PA 19104, USA.
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Vázquez-Novelle MD, Mailand N, Ovejero S, Bueno A, Sacristán MP. Human Cdc14A phosphatase modulates the G2/M transition through Cdc25A and Cdc25B. J Biol Chem 2010; 285:40544-53. [PMID: 20956543 PMCID: PMC3003353 DOI: 10.1074/jbc.m110.133009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The Cdc14 family of serine-threonine phosphatases antagonizes CDK activity by reversing CDK-dependent phosphorylation events. It is well established that the yeast members of this family bring about the M/G1 transition. Budding yeast Cdc14 is essential for CDK inactivation at the end of mitosis and fission yeast Cdc14 homologue Flp1/Clp1 down-regulates Cdc25 to ensure the inactivation of mitotic CDK complexes to trigger cell division. However, the functions of human Cdc14 homologues remain poorly understood. Here we have tested the hypothesis that Cdc14A might regulate Cdc25 mitotic inducers in human cells. We found that increasing levels of Cdc14A delay entry into mitosis by inhibiting Cdk1-cyclin B1 activity. By contrast, lowering the levels of Cdc14A accelerates mitotic entry. Biochemical analyses revealed that Cdc14A acts through key Cdk1-cyclin B1 regulators. We observed that Cdc14A directly bound to and dephosphorylated Cdc25B, inhibiting its catalytic activity. Cdc14A also regulated the activity of Cdc25A at the G2/M transition. Our results indicate that Cdc14A phosphatase prevents premature activation of Cdk1 regulating Cdc25A and Cdc25B at the entry into mitosis.
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Zhao H, Shi L, Cao JQ, Li W, Wen X, Zhao YQ. A new triterpene saponin from Panax japonicus C. A. Meyer var major (Burk.) C. Y. Wu et K. M. Feng. CHINESE CHEM LETT 2010. [DOI: 10.1016/j.cclet.2010.06.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Astuti P, Boutros R, Ducommun B, Gabrielli B. Mitotic phosphorylation of Cdc25B Ser321 disrupts 14-3-3 binding to the high affinity Ser323 site. J Biol Chem 2010; 285:34364-70. [PMID: 20801879 DOI: 10.1074/jbc.m110.138412] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc25B is a key regulator of entry into mitosis, and its activity and localization are regulated by binding of the 14-3-3 dimer. There are three 14-3-3 binding sites on Cdc25B, with Ser(323) being the highest affinity binding and is highly homologous to the Ser(216) 14-3-3 binding site on Cdc25C. Loss of 14-3-3 binding to Ser(323) increases cyclin/Cdk substrate access to the catalytic site, thereby increasing its activity. It also affects the localization of Cdc25B. Thus, phosphorylation and 14-3-3 binding to this site is essential for down-regulating Cdc25B activity, blocking its mitosis promoting function. The question of how this inhibitory signal is relieved to allow Cdc25B activation and entry into mitosis is yet to be resolved. Here, we show that Ser(323) phosphorylation is maintained into mitosis, but phosphorylation of Ser(321) disrupts 14-3-3 binding to Ser(323), mimicking the effect of inhibiting Ser(323) phosphorylation on both Cdc25B activity and localization. The unphosphorylated Ser(321) appears to have a role in stabilizing 14-3-3 binding to Ser(323), and loss of the Ser hydroxyl group appears to be sufficient to significantly reduce 14-3-3 binding. A consequence of loss of 14-3-3 binding is dephosphorylation of Ser(323). Ser(321) is phosphorylated in mitosis by Cdk1. The mitotic phosphorylation of Ser(321) acts to maintain full activation of Cdc25B by disrupting 14-3-3 binding to Ser(323) and enhancing the dephosphorylation of Ser(323) to block 14-3-3 binding to this site.
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Affiliation(s)
- Puji Astuti
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, Brisbane, Queensland 4102, Australia
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Franckhauser C, Mamaeva D, Heron-Milhavet L, Fernandez A, Lamb NJC. Distinct pools of cdc25C are phosphorylated on specific TP sites and differentially localized in human mitotic cells. PLoS One 2010; 5:e11798. [PMID: 20668692 PMCID: PMC2909920 DOI: 10.1371/journal.pone.0011798] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 07/06/2010] [Indexed: 12/24/2022] Open
Abstract
Background The dual specificity phosphatase cdc25C was the first human cdc25 family member found to be essential in the activation of cdk1/cyclin B1 that takes place at the entry into mitosis. Human cdc25C is phosphorylated on Proline-dependent SP and TP sites when it becomes active at mitosis and the prevalent model is that this phosphorylation/activation of cdc25C would be part of an amplification loop with cdk1/cyclin B1. Methodology/Principal Findings Using highly specific antibodies directed against cdc25C phospho-epitopes, pT67 and pT130, we show here that these two phospho-forms of cdc25C represent distinct pools with differential localization during human mitosis. Phosphorylation on T67 occurs from prophase and the cdc25C-pT67 phospho-isoform closely localizes with condensed chromosomes throughout mitosis. The phospho-T130 form of cdc25C arises in late G2 and associates predominantly with centrosomes from prophase to anaphase B where it colocalizes with Plk1. As shown by immunoprecipitation of each isoform, these two phospho-forms are not simultaneously phosphorylated on the other mitotic TP sites or associated with one another. Phospho-T67 cdc25C co-precipitates with MPM2-reactive proteins while pT130-cdc25C is associated with Plk1. Interaction and colocalization of phosphoT130-cdc25C with Plk1 demonstrate in living cells, that the sequence around pT130 acts as a true Polo Box Domain (PBD) binding site as previously identified from in vitro peptide screening studies. Overexpression of non-phosphorylatable alanine mutant forms for each isoform, but not wild type cdc25C, strongly impairs mitotic progression showing the functional requirement for each site-specific phosphorylation of cdc25C at mitosis. Conclusions/Significance These results show for the first time that in human mitosis, distinct phospho-isoforms of cdc25C exist with different localizations and interacting partners, thus implying that the long-standing model of a cdc25C/cdk1 multi-site auto amplification loop is implausible.
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Affiliation(s)
| | | | | | | | - Ned J. C. Lamb
- Cell Biology Unit, Institute de Genetique Humain, CNRS-UPR1142, Montpellier, France
- * E-mail:
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Timofeev O, Cizmecioglu O, Settele F, Kempf T, Hoffmann I. Cdc25 phosphatases are required for timely assembly of CDK1-cyclin B at the G2/M transition. J Biol Chem 2010; 285:16978-90. [PMID: 20360007 DOI: 10.1074/jbc.m109.096552] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Progression through mitosis requires the coordinated regulation of Cdk1 kinase activity. Activation of Cdk1 is a multistep process comprising binding of Cdk1 to cyclin B, relocation of cyclin-kinase complexes to the nucleus, activating phosphorylation of Cdk1 on Thr(161) by the Cdk-activating kinase (CAK; Cdk7 in metazoans), and removal of inhibitory Thr(14) and Tyr(15) phosphorylations. This dephosphorylation is catalyzed by the dual specific Cdc25 phosphatases, which occur in three isoforms in mammalian cells, Cdc25A, -B, and -C. We find that expression of Cdc25A leads to an accelerated G(2)/M phase transition. In Cdc25A-overexpressing cells, Cdk1 exhibits high kinase activity despite being phosphorylated on Tyr(15). In addition, Tyr(15)-phosphorylated Cdk1 binds more cyclin B in Cdc25A-overexpressing cells compared with control cells. Consistent with this observation, we demonstrate that in human transformed cells, Cdc25A and Cdc25B, but not Cdc25C phosphatases have an effect on timing and efficiency of cyclin-kinase complex formation. Overexpression of Cdc25A or Cdc25B promotes earlier assembly and activation of Cdk1-cyclin B complexes, whereas repression of these phosphatases by short hairpin RNA has a reverse effect, leading to a substantial decrease in amounts of cyclin B-bound Cdk1 in G(2) and mitosis. Importantly, we find that Cdc25A overexpression leads to an activation of Cdk7 and increase in Thr(161) phosphorylation of Cdk1. In conclusion, our data suggest that complex assembly and dephosphorylation of Cdk1 at G(2)/M is tightly coupled and regulated by Cdc25 phosphatases.
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Affiliation(s)
- Oleg Timofeev
- Cell Cycle Control and Carcinogenesis, German Cancer Research Center, F045, Im Neuenheimer Feld 242, D-69120 Heidelberg, Germany
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Gustafsson N, Zhao C, Gustafsson JÅ, Dahlman-Wright K. RBCK1 Drives Breast Cancer Cell Proliferation by Promoting Transcription of Estrogen Receptor α and Cyclin B1. Cancer Res 2010; 70:1265-74. [DOI: 10.1158/0008-5472.can-09-2674] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Pan HA, Lee YC, Teng YN, Tsai SJ, Lin YM, Kuo PL. CDC25 protein expression and interaction with DAZL in human corpus luteum. Fertil Steril 2009; 92:1997-2003. [DOI: 10.1016/j.fertnstert.2008.09.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 09/05/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
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70
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LGH00031, a novel ortho-quinonoid inhibitor of cell division cycle 25B, inhibits human cancer cells via ROS generation. Acta Pharmacol Sin 2009; 30:1359-68. [PMID: 19730430 DOI: 10.1038/aps.2009.131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
AIM To discover novel cell division cycle 25 (CDC25) B inhibitors and elucidate the mechanisms of inhibition in cancer cells. METHODS Cell growth inhibition was detected by MTT assay, the cell cycle was analyzed by flow cytometry, and protein expression and phosphorylation was examined by Western blot analysis. RESULTS LGH00031 inhibited CDC25B irreversibly in vitro in a dose-dependent manner, and impaired the proliferation of tumor cell lines. In synchronized HeLa cells, LGH00031 delayed the cell cycle progression at the G(2)/M phase. LGH00031 increased cyclin-dependent kinase 1 (CDK1) tyrosine 15 phosphorylation and cyclin B1 protein level. The activity of LGH00031 against CDC25B in vitro relied on the existence of 1,4-dithiothreitol (DTT) or dihydrolipoic acid and oxygen. The oxygen free radical scavenger catalase and superoxide dismutase reduced the inactivation of CDC25 by LGH00031, confirming that reactive oxygen species (ROS) mediate the inactivation process in vitro. LGH00031 accelerated cellular ROS production in a dose-dependent manner, and N-acetyl cysteine (NAC) markedly decreased the ROS production induced by LGH00031. Correspondingly, the LGH00031-induced decrease in cell viability and cell cycle arrest, cyclin B1 protein level, and phosphorylation of CDK1 tyrosine 15 were also rescued by NAC that decreased ROS production. CONCLUSION The activity of LGH00031 at the molecular and cellular level is mediated by ROS.
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71
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Dissecting the role of ubiquitylation in the DNA damage response checkpoint in G2. Cell Death Differ 2009; 17:78-85. [DOI: 10.1038/cdd.2009.104] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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72
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Kolb S, Mondésert O, Goddard ML, Jullien D, Villoutreix BO, Ducommun B, Garbay C, Braud E. Development of novel thiazolopyrimidines as CDC25B phosphatase inhibitors. ChemMedChem 2009; 4:633-48. [PMID: 19212959 DOI: 10.1002/cmdc.200800415] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The development of CDC25 phosphatase inhibitors is an interesting approach toward new antitumor agents, as CDC25 play key roles in cell-cycle regulation and are overexpressed in numerous cancers. We previously reported a novel compound belonging to the thiazolopyrimidine family that inhibits CDC25 activity with an IC(50) value of 13 microM and displays cytotoxic properties against HeLa cells. Structural modifications were subsequently conducted on this new pharmacophore which led to a library of 45 thiazolopyrimidines. Regarding the in vitro effects, 14 compounds inhibit CDC25B with IC(50)<20 microM, with the most efficient inhibitor 44 improving the potency to 4.5 microM. Steady-state kinetics were performed and showed a mixed inhibition pattern for all tested compounds. Furthermore, 44 was able to revert the bypass of genotoxicity-induced G(2) arrest upon CDC25B overexpression, indicating that this compound targets the dual-specificity phosphatase in cultured cells. Finally, the cytotoxic activities of the compounds were determined against two human cancer cell lines. The results indicate that the prostatic LNCaP cell line is more sensitive to these derivatives than the pancreatic adenocarcinoma MiaPaCa-2 line. With its interesting enzymatic and cellular properties, compound 44 appears to be a promising CDC25B inhibitor for further development.
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73
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Lindqvist A, Rodríguez-Bravo V, Medema RH. The decision to enter mitosis: feedback and redundancy in the mitotic entry network. ACTA ACUST UNITED AC 2009; 185:193-202. [PMID: 19364923 PMCID: PMC2700378 DOI: 10.1083/jcb.200812045] [Citation(s) in RCA: 410] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The decision to enter mitosis is mediated by a network of proteins that regulate activation of the cyclin B–Cdk1 complex. Within this network, several positive feedback loops can amplify cyclin B–Cdk1 activation to ensure complete commitment to a mitotic state once the decision to enter mitosis has been made. However, evidence is accumulating that several components of the feedback loops are redundant for cyclin B–Cdk1 activation during normal cell division. Nonetheless, defined feedback loops become essential to promote mitotic entry when normal cell cycle progression is perturbed. Recent data has demonstrated that at least three Plk1-dependent feedback loops exist that enhance cyclin B–Cdk1 activation at different levels. In this review, we discuss the role of various feedback loops that regulate cyclin B–Cdk1 activation under different conditions, the timing of their activation, and the possible identity of the elusive trigger that controls mitotic entry in human cells.
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Affiliation(s)
- Arne Lindqvist
- Department of Medical Oncology, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands
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74
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Lim D, Jocelyn KMX, Yip GWC, Bay BH. Silencing the Metallothionein-2A gene inhibits cell cycle progression from G1- to S-phase involving ATM and cdc25A signaling in breast cancer cells. Cancer Lett 2009; 276:109-17. [DOI: 10.1016/j.canlet.2008.10.038] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 10/15/2008] [Accepted: 10/28/2008] [Indexed: 12/11/2022]
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75
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Lobjois V, Jullien D, Bouché JP, Ducommun B. The polo-like kinase 1 regulates CDC25B-dependent mitosis entry. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1793:462-8. [PMID: 19185590 DOI: 10.1016/j.bbamcr.2008.12.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Revised: 12/13/2008] [Accepted: 12/17/2008] [Indexed: 12/19/2022]
Abstract
Activation of cyclin-dependent kinase complexes (CDK) at key cell cycle transitions is dependent on their dephosphorylation by CDC25 dual-specificity phosphatases (CDC25A, B and C in human). The CDC25B phosphatase plays an essential role in controlling the activity of CDK1-cyclin B complexes at the entry into mitosis and together with polo-like kinase 1 (PLK1) in regulating the resumption of cell cycle progression after DNA damage-dependent checkpoint arrest in G2. In this study, we analysed the regulation of CDC25B-dependent mitosis entry by PLK1. We demonstrate that PLK1 activity is essential for the relocation of CDC25B from the cytoplasm to the nucleus. By gain and loss of function analyses, we show that PLK1 stimulates CDC25B-induced mitotic entry in both normal conditions and after DNA-damage induced G2/M arrest. Our results support a model in which the relocalisation of CDC25B to the nucleus at the G2-M transition by PLK1 regulates its mitotic inducing activity.
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Affiliation(s)
- Valerie Lobjois
- Université de Toulouse, LBCMCP, 118 Route de Narbonne, CNRS, LBCMCP-UMR5088, F-31062 Toulouse, France
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76
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Varmeh S, Manfredi JJ. Inappropriate activation of cyclin-dependent kinases by the phosphatase Cdc25b results in premature mitotic entry and triggers a p53-dependent checkpoint. J Biol Chem 2009; 284:9475-88. [PMID: 19136558 DOI: 10.1074/jbc.m900037200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dual specificity phosphatase Cdc25B is capable of inhibiting cellular proliferation, and this occurs in a manner dependent upon its catalytic activity. Here it is shown that this is accompanied by inappropriate cyclin-dependent kinase activation and premature mitotic entry, leading to both p53-dependent and independent checkpoints. Forced expression of Cdc25B inappropriately up-regulated the activity of Cdk1 and Cdk2, by reducing levels of inhibitory phosphorylation. In cells lacking p14ARF, p53 is induced, and components of the ATM and ATR pathways are activated. Cdc25B triggers cell cycle arrest in the G(1) and G(2) phases that is p53- and p21-dependent and is inhibited by caffeine. Cdc25B also causes cells with an S phase DNA content to enter mitosis prematurely in a p53-independent manner. Synchronization of cells with aphidicolin results in these cells undergoing apoptosis. Thus, inappropriate cell cycle progression and premature mitotic entry via dysregulation of cyclin-dependent kinases results in activation of both p53-dependent and independent responses. Because Cdc25B is known to have oncogenic activity, this provides insight into the multistep nature of cancer development and why there is p53 loss during tumorigenesis.
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Affiliation(s)
- Shohreh Varmeh
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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77
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Cao S, Murphy BT, Foster C, Lazo JS, Kingston DGI. Bioactivities of simplified adociaquinone B and naphthoquinone derivatives against Cdc25B, MKP-1, and MKP-3 phosphatases. Bioorg Med Chem 2008; 17:2276-81. [PMID: 19028102 DOI: 10.1016/j.bmc.2008.10.090] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 10/03/2008] [Accepted: 10/31/2008] [Indexed: 12/21/2022]
Abstract
Some simplified adociaquinone B analogs and a series of 1,4-naphthoquinone derivatives were synthesized and tested against the three enzymes Cdc25B, MKP-1, and MKP-3. Cdc25B and MKP-1 in particular are enzymes overexpressed in human cancer cells, and they represent potential molecular targets for novel cancer chemotherapeutic treatments. A number of analogs exhibited significant inhibitory activity against these enzymes, and the bioassay data in addition to structure-activity relationships of these compounds will be discussed.
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Affiliation(s)
- Shugeng Cao
- Department of Chemistry, Virginia Polytechnic Institute and State University, 3111 Hahn Hall, M/C 0212, Blacksburg, VA 24061, USA
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78
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Cdc25A serine 123 phosphorylation couples centrosome duplication with DNA replication and regulates tumorigenesis. Mol Cell Biol 2008; 28:7442-50. [PMID: 18936171 DOI: 10.1128/mcb.00138-08] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cell division cycle 25A (Cdc25A) phosphatase is a critical regulator of cell cycle progression under normal conditions and after stress. Stress-induced degradation of Cdc25A has been proposed as a major way of delaying cell cycle progression. In vitro studies pointed toward serine 123 as a key site in regulation of Cdc25A stability after exposure to ionizing radiation (IR). To address the role of this phosphorylation site in vivo, we generated a knock-in mouse in which alanine was substituted for serine 123. The Cdc25 S123A knock-in mice appeared normal, and, unexpectedly, cells derived from them exhibited unperturbed cell cycle and DNA damage responses. In turn, we found that Cdc25A was present in centrosomes and that Cdc25A levels were not reduced after IR in knock-in cells. This resulted in centrosome amplification due to lack of induction of Cdk2 inhibitory phosphorylation after IR specifically in centrosomes. Further, Cdc25A knock-in animals appeared sensitive to IR-induced carcinogenesis. Our findings indicate that Cdc25A S123 phosphorylation is crucial for coupling centrosome duplication to DNA replication cycles after DNA damage and therefore is likely to play a role in the regulation of tumorigenesis.
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79
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Feng X, Wang LN, Zhou YY, Yu HP, Shen Q, Zang Y, Zhou YB, Li JY, Zhang HX, Li J. Discovery and characterization of a novel inhibitor of CDC25B, LGH00045. Acta Pharmacol Sin 2008; 29:1268-74. [PMID: 18817634 DOI: 10.1111/j.1745-7254.2008.00841.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
AIM Cell division cycle 25 (CDC25) phosphatases have recently been considered as potential targets for the development of new cancer therapeutic agents. We aimed to discover novel CDC25B inhibitors in the present study. METHODS A molecular level high-throughput screening (HTS) assay was set up to screen a set of 48000 pure compounds. RESULTS HTS, whose average Z' factor is 0.55, was finished and LGH00045, a mixed-type CDC25B inhibitor with a novel structure and relative selectivity for protein tyrosine phosphatases, was identified. Furthermore, LGH00045 impaired the proliferation of tumor cells and increased cyclin-dependent kinase 1 inhibitory tyrosine phosphorylation. In synchronized HeLa cells, LGH00045 delayed cell cycle progression at the G2-M transition. CONCLUSION LGH00045, a novel CDC25B inhibitor identified through HTS, showed good inhibition on the proliferation of tumor cells and affected the cell cycle progression, which makes it a good hit for further structure modification.
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Affiliation(s)
- Xu Feng
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
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80
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Constitutive overexpression of CDC25A in primary human mammary epithelial cells results in both defective DNA damage response and chromosomal breaks at fragile sites. Int J Cancer 2008; 123:1466-71. [DOI: 10.1002/ijc.23659] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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81
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Liu WL, Zhang G, Wang JY, Cao JY, Guo XZ, Xu LH, Li MZ, Song LB, Huang WL, Zeng MS. Proteomics-based identification of autoantibody against CDC25B as a novel serum marker in esophageal squamous cell carcinoma. Biochem Biophys Res Commun 2008; 375:440-5. [PMID: 18722351 DOI: 10.1016/j.bbrc.2008.08.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 08/07/2008] [Indexed: 12/31/2022]
Abstract
This study was aimed to identify tumor proteins that elicit a humoral response in patients with esophageal squamous cell carcinoma (ESCC). Autologous sera of 15 newly diagnosed patients with ESCC and age- and gender-matched 15 healthy controls were analyzed individually for antibody-based reactivity against proteins from 15 homogenized ESCC tissue mixture resolved by two-dimensional PAGE. One protein spot, which reacted with sera from ESCC patients but not with those from controls, was identified to be CDC25B by mass spectrometry and Western blotting. High expression of CDC25B was detected in ESCC cell lines and primary tumor tissues, but not in normal esophageal tissues. In addition, CDC25B expression was significantly higher in tumor tissue of patients with sera positive CDC25B-Abs than that of patients without CDC25B-Abs. Finally, anti-CDC25B antibodies were readily detectable in sera from 45 of 124 (36.29%) patients with ESCC, 13 of 150 (8.67%) patients with other types of cancer and 0 of 102 (0%) of healthy individuals. Thus, CDC25B autoantibodies may have clinical utility in ESCC screening and diagnosis.
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Affiliation(s)
- Wan-Li Liu
- Department of Research, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China
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82
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Braud E, Goddard ML, Kolb S, Brun MP, Mondésert O, Quaranta M, Gresh N, Ducommun B, Garbay C. Novel naphthoquinone and quinolinedione inhibitors of CDC25 phosphatase activity with antiproliferative properties. Bioorg Med Chem 2008; 16:9040-9. [PMID: 18789703 DOI: 10.1016/j.bmc.2008.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/29/2008] [Accepted: 08/04/2008] [Indexed: 10/21/2022]
Abstract
CDC25 phosphatases are considered as attractive targets for anti-cancer therapy. To date, quinone derivatives are among the most potent inhibitors of CDC25 phosphatase activity. We present in this paper the synthesis and the biological evaluation of new quinolinedione and naphthoquinone derivatives, containing carboxylic or malonic acids groups introduced to mimic the role of the phosphate moieties of Cyclin-Dependent Kinase complexes. The most efficient compounds show inhibitory activity against CDC25B with IC(50) values in the 10 microM range, and are cytotoxic against HeLa cells.
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Affiliation(s)
- Emmanuelle Braud
- Université Paris Descartes, UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, 45 rue des Saints-Pères, Paris F-75006, France
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83
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Cunat S, Anahory T, Berthenet C, Hedon B, Franckhauser C, Fernandez A, Hamamah S, Lamb NJC. The cell cycle control protein cdc25C is present, and phosphorylated on serine 214 in the transition from germinal vesicle to metaphase II in human oocyte meiosis. Mol Reprod Dev 2008; 75:1176-84. [PMID: 18161793 DOI: 10.1002/mrd.20853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cdc25C is a dual specificity phosphatase essential for dephosphorylation and activation of cyclin-dependent kinase 1 (cdk1), a prerequisite step for mitosis in all eucaryotes. Cdc25C activation requires phosphorylation on at least six sites including serine 214 (S214) which is essential for metaphase/anaphase transit. Here, we have investigated S214 phosphorylation during human meiosis with the objectives of determining if this mitotic phosphatase cdc25C participates in final meiotic divisions in human oocytes. One hundred forty-eight human oocytes from controlled ovarian stimulation protocols were stained for immunofluorescence: 33 germinal vesicle (GV), 37 metaphase stage I (MI), and 78 unfertilized metaphase stage II (MII). Results were stage dependent, identical, independent of infertility type, or stimulation protocol. During GV stages, phospho-cdc25C is localized at the oocyte periphery. During early meiosis I (MI), phosphorylated cdc25C is no longer detected until onset of meiosis I. Here, phospho-cdc25C localizes on interstitial microtubules and at the cell periphery corresponding to the point of polar body expulsion. As the first polar body reaches the periphery, phosphorylated cdc25C is localized at the junction corresponding to the mid body position. On polar body expulsion, the interior signal for phospho-cdc25C is lost, but remains clearly visible in the extruded polar body. In atresic or damaged oocytes, the polar body no longer stains for phospho-cdc25C. Human cdc25C is both present and phosphorylated during meiosis I and localizes in a fashion similar to that seen during human mitotic divisions implying that the involvement of cdc25C is conserved and functional in meiotic cells.
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Affiliation(s)
- S Cunat
- Institut de Génétique Humaine, CNRS UPR 1142, Biologie Cellulaire, Prolifération et Différenciation Cellulaire, Montpellier Cedex, France
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84
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Duraisamy S, Bajpai M, Bughani U, Dastidar SG, Ray A, Chopra P. MK2: a novel molecular target for anti-inflammatory therapy. Expert Opin Ther Targets 2008; 12:921-36. [DOI: 10.1517/14728222.12.8.921] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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85
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Bonnet J, Mayonove P, Morris MC. Differential phosphorylation of Cdc25C phosphatase in mitosis. Biochem Biophys Res Commun 2008; 370:483-8. [PMID: 18384749 DOI: 10.1016/j.bbrc.2008.03.117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 03/24/2008] [Indexed: 01/24/2023]
Abstract
Cdc25 dual-specificity phosphatases coordinate entry into mitosis through activating dephosphorylation of the Mitosis-Promoting Factor, Cdk1-cyclin B1. Activation of Cdc25C at the G2/M transition, involves its dissociation from 14-3-3, together with its hyperphosphorylation on several sites within its regulatory N-terminal domain, mediated by cyclin-dependent kinases and Plk1. Growing evidence suggests that phosphorylation intermediates are likely to precede complete hyperphosphorylation of Cdc25C. To address whether such variants occur in mitotic cells, we raised antibodies directed against different mitotic phosphorylation sites of human Cdc25C, and characterized the phosphorylated species detectable in HeLa cells. In the present study, we provide first-time evidence for the existence of multiple species of Cdc25C in mitotic cell extracts, including full-length and splice variants with different phosphorylation patterns, thereby revealing an intricate network of Cdc25C phosphatases, likely to have distinct biological functions.
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Affiliation(s)
- Jérôme Bonnet
- Université de Montpellier, CRBM-CNRS-UMR 5237, Interactions & Molecular Mechanisms regulating Cell Cycle Progression, 1919 Route de Mende, IFR 122, 34293 Montpellier, France.
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86
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Bouché JP, Froment C, Dozier C, Esmenjaud-Mailhat C, Lemaire M, Monsarrat B, Burlet-Schiltz O, Ducommun B. NanoLC-MS/MS analysis provides new insights into the phosphorylation pattern of Cdc25B in vivo: full overlap with sites of phosphorylation by Chk1 and Cdk1/cycB kinases in vitro. J Proteome Res 2008; 7:1264-73. [PMID: 18237113 DOI: 10.1021/pr700623p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
NanoLC-MS/MS analysis was used to characterize the phosphorylation pattern in vivo of CDC25B3 (phosphatase splice variant 1) expressed in a human cell line and to compare it to the phosphorylation of CDC25B3 by Cdk1/cyclin B and Chk1 in vitro. Cellular CDC25B3 was purified from U2OS cells conditionally overexpressing the phosphatase. Eighteen sites were detectably phosphorylated in vivo. Nearly all existing (S/T)P sites were phosphorylated in vivo and in vitro. Eight non(S/T)P sites were phosphorylated in vivo. All these sites could be phosphorylated by kinase Chk1, which phosphorylated a total of 11 sites in vitro, with consensus sequence (R/K) X(2-3) (S/P)-non P. Nearly half of the sites identified in this study were not previously described and were not homologous to sites reported to be phosphorylated in other CDC25 species. We also show that in vivo a significant part of CDC25B molecules can be hyperphosphorylated, with up to 13 phosphates per phosphatase molecule.
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Affiliation(s)
- Jean-Pierre Bouché
- LBCMCP-CNRS-IFR109, Institut d'Exploration Fonctionnelle des Génomes, University of Toulouse, France.
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87
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Kodym E, Kodym R, Choy H, Saha D. Sustained Metaphase Arrest in Response to Ionizing Radiation in a Non-small Cell Lung Cancer Cell Line. Radiat Res 2008; 169:46-58. [DOI: 10.1667/rr0937.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Accepted: 09/18/2007] [Indexed: 11/03/2022]
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88
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Feng C, Yu A, Liu Y, Zhang J, Zong Z, Su W, Zhang Z, Yu D, Sun QY, Yu B. Involvement of Protein Kinase B/AKT in Early Development of Mouse Fertilized Eggs1. Biol Reprod 2007; 77:560-8. [PMID: 17554083 DOI: 10.1095/biolreprod.107.060269] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The activation of AKT (also called protein kinase B) is thought to be a critical step in the phosphoinositide 3-kinase pathway that regulates cell growth and differentiation. In this report, we investigated the role of AKT in the regulation of mouse early embryo development. Injection of mRNA coding for a constitutively active myristoylated AKT (myr-Akt1) into one-cell stage fertilized eggs induced cell division more effectively than injection of wild-type AKT (Akt1-WT) mRNA, whereas microinjection of mRNA of kinase-deficient AKT (Akt1-KD) delayed the first mitotic division. Meanwhile, microinjection of different kinds of mRNA of AKT affected the phosphorylation status of CDC2A-Tyr15 and the activation of M-phase promoting factor (MPF). To investigate the intermediate factor between AKT and MPF, we then injected one-cell stage eggs first with Akt1-WT mRNA or myr-Akt1 mRNA and then with mRNA encoding either wild-type CDC25B (Cdc25b-WT) or a AKT-nonphosphorylatable Ser351 to Ala CDC25B mutant (Cdc25b-S351A). Cdc25b-S351A strongly inhibited the effect of AKT. Therefore, AKT causes the activation of MPF and strongly promotes the development of one-cell stage mouse fertilized eggs by inducing AKT-dependent phosphorylation of CDC25B, a member of the CDC25 phosphatase family. Our finding that CDC25B acts as a potential target of AKT provides new insight into the effect of AKT in the regulation of early development of mouse embryos.
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Affiliation(s)
- Chen Feng
- Department of Biochemical and Molecular Biology, China Medical University, Shenyang 110001, Liaoning, China
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89
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Teng YN, Chung CL, Lin YM, Pan HA, Liao RW, Kuo PL. Expression of various CDC25B isoforms in human spermatozoa. Fertil Steril 2007; 88:379-82. [PMID: 17336969 DOI: 10.1016/j.fertnstert.2006.11.186] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 11/07/2006] [Accepted: 11/21/2006] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To explore the role of CDC25B protein in postmeiotic germ cells. DESIGN In vitro experiment. SETTING University-based reproductive genetics laboratory. PATIENT(S) Fertile and infertile volunteers. INTERVENTION(S) Reverse transcription-polymerase chain reaction (RT-PCR), real-time RT-PCR, and immunostaining for CDC25B. MAIN OUTCOME MEASURE Expression profiling of CDC25B in human spermatozoa. RESULT(S) Four splicing variants (CDC25B1, B2, B3, and B4) are expressed in human spermatozoa. Immunofluorescence staining showed strong homogeneous staining in the midpiece of spermatozoa, and weak staining in the principal piece and cytosol of the head. The messenger RNA (mRNA) transcript level of CDC25B was increased in sperm samples of men with asthenospermia. CONCLUSION(S) The expression of CDC25B in different cellular compartments of human spermatozoa suggests that there are diverse noncell-cycle-related functions of CDC25B in terminally differentiated human germ cells.
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Affiliation(s)
- Yen-Ni Teng
- Department of Biotechnology, Chia Nan University of Pharmacy and Science, National Cheng Kung University, College of Medicine, Tainan, Taiwan
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90
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Esmenjaud-Mailhat C, Lobjois V, Froment C, Golsteyn RM, Monsarrat B, Ducommun B. Phosphorylation of CDC25C at S263 controls its intracellular localisation. FEBS Lett 2007; 581:3979-85. [PMID: 17662724 DOI: 10.1016/j.febslet.2007.07.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Revised: 07/06/2007] [Accepted: 07/11/2007] [Indexed: 11/26/2022]
Abstract
CDC25C phosphatase is a key actor in cell cycle progression that controls the activation of CDK1-cyclin B at mitosis. Its activity is known to be highly regulated by a number of signalling pathway-activated kinases resulting in its phosphorylation on multiple residues. In this study, we have purified CDC25C from cells and have used a proteomic approach to identify new regulatory phosphorylations. Here, we report the identification by mass spectrometry of a peptide monophosphorylated on serine 263. We demonstrate by cell imaging that mutation of S263 to alanine leads to a nuclear accumulation of CDC25C that is further reinforced by leptomycin-B. We propose that phosphorylation at S263 is part of the regulatory mechanism that modulates nuclear import of CDC25C, thus preventing cytoplasm to nucleus shuttling.
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Affiliation(s)
- Charlotte Esmenjaud-Mailhat
- LBCMCP-CNRS, IFR109 Institut d'Exploration Fonctionnelle des Génomes, University of Toulouse, 118 Route de Narbonne, 31062 Toulouse, France
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91
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Schmitt E, Paquet C, Beauchemin M, Bertrand R. DNA-damage response network at the crossroads of cell-cycle checkpoints, cellular senescence and apoptosis. J Zhejiang Univ Sci B 2007; 8:377-97. [PMID: 17565509 PMCID: PMC1879163 DOI: 10.1631/jzus.2007.b0377] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Tissue homeostasis requires a carefully-orchestrated balance between cell proliferation, cellular senescence and cell death. Cells proliferate through a cell cycle that is tightly regulated by cyclin-dependent kinase activities. Cellular senescence is a safeguard program limiting the proliferative competence of cells in living organisms. Apoptosis eliminates unwanted cells by the coordinated activity of gene products that regulate and effect cell death. The intimate link between the cell cycle, cellular senescence, apoptosis regulation, cancer development and tumor responses to cancer treatment has become eminently apparent. Extensive research on tumor suppressor genes, oncogenes, the cell cycle and apoptosis regulatory genes has revealed how the DNA damage-sensing and -signaling pathways, referred to as the DNA-damage response network, are tied to cell proliferation, cell-cycle arrest, cellular senescence and apoptosis. DNA-damage responses are complex, involving "sensor" proteins that sense the damage, and transmit signals to "transducer" proteins, which, in turn, convey the signals to numerous "effector" proteins implicated in specific cellular pathways, including DNA repair mechanisms, cell-cycle checkpoints, cellular senescence and apoptosis. The Bcl-2 family of proteins stands among the most crucial regulators of apoptosis and performs vital functions in deciding whether a cell will live or die after cancer chemotherapy and irradiation. In addition, several studies have now revealed that members of the Bcl-2 family also interface with the cell cycle, DNA repair/recombination and cellular senescence, effects that are generally distinct from their function in apoptosis. In this review, we report progress in understanding the molecular networks that regulate cell-cycle checkpoints, cellular senescence and apoptosis after DNA damage, and discuss the influence of some Bcl-2 family members on cell-cycle checkpoint regulation.
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Affiliation(s)
- Estelle Schmitt
- Notre Dame Hospital and Montreal Cancer Institute, Research Centre of University of Montreal Hospital Centre (CRCHUM), Montreal (Que) H2L 4M1, Canada
| | - Claudie Paquet
- Notre Dame Hospital and Montreal Cancer Institute, Research Centre of University of Montreal Hospital Centre (CRCHUM), Montreal (Que) H2L 4M1, Canada
| | - Myriam Beauchemin
- Notre Dame Hospital and Montreal Cancer Institute, Research Centre of University of Montreal Hospital Centre (CRCHUM), Montreal (Que) H2L 4M1, Canada
| | - Richard Bertrand
- Notre Dame Hospital and Montreal Cancer Institute, Research Centre of University of Montreal Hospital Centre (CRCHUM), Montreal (Que) H2L 4M1, Canada
- Medicine Department, University of Montreal, Montreal (Que) H3C 3J7, Canada
- †E-mail:
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92
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Abstract
Cell division cycle 25 (CDC25) phosphatases regulate key transitions between cell cycle phases during normal cell division, and in the event of DNA damage they are key targets of the checkpoint machinery that ensures genetic stability. Taking only this into consideration, it is not surprising that CDC25 overexpression has been reported in a significant number of human cancers. However, in light of the significant body of evidence detailing the stringent complexity with which CDC25 activities are regulated, the significance of CDC25 overexpression in a subset of cancers and its association with poor prognosis are proving difficult to assess. We will focus on the roles of CDC25 phosphatases in both normal and abnormal cell proliferation, provide a critical assessment of the current data on CDC25 overexpression in cancer, and discuss both current and future therapeutic strategies for targeting CDC25 activity in cancer treatment.
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Affiliation(s)
- Rose Boutros
- LBCMCP-CNRS UMR5088, IFR109 Institut d'Exploration Fonctionnelle des Génomes, University of Toulouse, 118 route de Narbonne, 31062 Toulouse, France
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93
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Varmeh-Ziaie S, Manfredi JJ. The dual specificity phosphatase Cdc25B, but not the closely related Cdc25C, is capable of inhibiting cellular proliferation in a manner dependent upon its catalytic activity. J Biol Chem 2007; 282:24633-41. [PMID: 17591782 DOI: 10.1074/jbc.m703105200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc25B and Cdc25C are closely related dual specificity phosphatases that activate cyclin-dependent kinases by removal of inhibitory phosphorylations, thereby triggering entry into mitosis. Cdc25B, but not Cdc25C, has been implicated as an oncogene and been shown to be overexpressed in a variety of human tumors. Surprisingly, ectopic expression of Cdc25B, but not Cdc25C, inhibits cell proliferation in long term assays. Chimeric proteins generated from the two phosphatases show that the anti-proliferative activity is associated with the C-terminal end of Cdc25B. Indeed, the catalytic domain of Cdc25B is sufficient to suppress cell viability in a manner partially dependent upon its C-terminal 26 amino acids that is shown to influence substrate binding. Mutation analysis demonstrates that both the phosphatase activity of Cdc25B as well as its ability to interact with its substrates contribute to the inhibition of cell proliferation. These results demonstrate key differences in the biological activities of Cdc25B and Cdc25C caused by differential substrate affinity and recognition. This also argues that the antiproliferative activity of Cdc25B needs to be overcome for it to act as an oncogene during tumorigenesis.
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Affiliation(s)
- Shohreh Varmeh-Ziaie
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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94
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Tazuke Y, Wildhaber BE, Yang H, Washburn J, Teitelbaum DH. Total parenteral nutrition leads to alteration of hepatocyte cell cycle gene expression and proliferation in the mouse. Dig Dis Sci 2007; 52:920-30. [PMID: 17342396 DOI: 10.1007/s10620-006-9364-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Accepted: 01/30/2006] [Indexed: 12/09/2022]
Abstract
Total parenteral nutrition (TPN) is correlated with progressive liver injury. Such injury may be associated with either an increase or decrease in hepatocyte growth. The goal of these experiments was to determine TPN-related alterations in intrahepatic genes, as they relate with the cell cycle, using microarray techniques. After 7 days of infusion of saline or TPN-solution, hepatocyte gene expression was examined with a 5000-cDNA microarray chip. TPN was associated with an up-regulation of the cyclin kinase Cdc25B mRNA, which controls the cell cycle at the G2/M phase. Based on this, our studies were directed at alterations in genes related to mitosis in this phase of the cell cycle. mRNA expression of mitotic phase inducers and inhibitors were examined. Cdc25B1 mRNA expression increased with TPN. TPN also led to additional significant alterations in the expression of other factors which mediate proliferation in this phase of mitosis. Histologically, TPN resulted in a significant decline in hepatocyte proliferation. Coincident with the alteration in cyclin expression was a significant decrease in hepatocytes in the G2/M phase with TPN administration. This study demonstrates significant alterations in cell cycle gene expression with TPN. The findings correlate with a loss of hepatocyte proliferation and may give insight into the potential mechanism of TPN-induced hepatocyte injury.
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Affiliation(s)
- Yuko Tazuke
- Section of Pediatric Surgery, C.S. Mott Children's Hospital, Department of Surgery, University of Michigan Medical School, F3970 Mott Children's Hospital, Box 0245, Ann Arbor, MI 48109, USA
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95
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Schmidt A, Durgan J, Magalhaes A, Hall A. Rho GTPases regulate PRK2/PKN2 to control entry into mitosis and exit from cytokinesis. EMBO J 2007; 26:1624-36. [PMID: 17332740 PMCID: PMC1829391 DOI: 10.1038/sj.emboj.7601637] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 02/05/2007] [Indexed: 01/20/2023] Open
Abstract
Rho GTPases regulate multiple signal transduction pathways that influence many aspects of cell behaviour, including migration, morphology, polarity and cell cycle. Through their ability to control the assembly and organization of the actin and microtubule cytoskeletons, Rho and Cdc42 make several key contributions during the mitotic phase of the cell cycle, including spindle assembly, spindle positioning, cleavage furrow contraction and abscission. We now report that PRK2/PKN2, a Ser/Thr kinase and Rho/Rac effector protein, is an essential regulator of both entry into mitosis and exit from cytokinesis in HeLa S3 cells. PRK2 is required for abscission of the midbody at the end of the cell division cycle and for phosphorylation and activation of Cdc25B, the phosphatase required for activation of mitotic cyclin/Cdk1 complexes at the G2/M transition. This reveals an additional step in the mammalian cell cycle controlled by Rho GTPases.
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Affiliation(s)
- Anja Schmidt
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London, UK
| | - Joanne Durgan
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London, UK
- Present address: Memorial Sloan-Kettering Cancer Center, 1275 York Avenue Box 572, New York, NY 10021, USA
| | - Ana Magalhaes
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London, UK
- Present address: Memorial Sloan-Kettering Cancer Center, 1275 York Avenue Box 572, New York, NY 10021, USA
| | - Alan Hall
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London, UK
- Present address: Memorial Sloan-Kettering Cancer Center, 1275 York Avenue Box 572, New York, NY 10021, USA
- Memorial Sloan-Kettering Cancer Center, 1275 York Avenue Box 572, New York, NY 10021, USA. Tel./Fax: +1 212 639 2387; E-mail:
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96
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Rudolph J. Inhibiting transient protein-protein interactions: lessons from the Cdc25 protein tyrosine phosphatases. Nat Rev Cancer 2007; 7:202-11. [PMID: 17287826 DOI: 10.1038/nrc2087] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Transient protein-protein interactions have key regulatory functions in many of the cellular processes that are implicated in cancerous growth, particularly the cell cycle. Targeting these transient interactions as therapeutic targets for anticancer drug development seems like a good idea, but it is not a trivial task. This Review discusses the issues and difficulties that are encountered when considering these transient interactions as drug targets, using the example of the cell division cycle 25 (Cdc25) phosphatases and their cyclin-dependent kinase (CDK)-cyclin protein substrates.
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Affiliation(s)
- Johannes Rudolph
- Department of Biochemistry, Duke University Medical Center, BOX 3813, LSRC Building, Room C125, Durham, North Carolina 27710, USA.
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97
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Brault L, Denancé M, Banaszak E, El Maadidi S, Battaglia E, Bagrel D, Samadi M. Synthesis and biological evaluation of dialkylsubstituted maleic anhydrides as novel inhibitors of Cdc25 dual specificity phosphatases. Eur J Med Chem 2007; 42:243-7. [PMID: 17084000 DOI: 10.1016/j.ejmech.2006.09.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 09/18/2006] [Accepted: 09/21/2006] [Indexed: 11/20/2022]
Abstract
An efficient synthesis of dialkylsubstituted maleic anhydrides 1a-j is described. The inhibitory potential of these original anhydride derivatives was tested toward the three human isoforms A, B and C of dual specific phosphatases Cdc25. A micromolar range inhibition of Cdc25s was observed with the maleic anhydrides bearing simple alkyl side chains longer than C(9), to reach the optimal activity with a C(17) chain length.
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Affiliation(s)
- Laurent Brault
- LIMBP, Université Paul Verlaine-Metz, Metz Technopôle, 57078 Metz, France
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98
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Zhao RY, Elder RT, Bukrinsky M. Interactions of HIV-1 viral protein R with host cell proteins. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2007; 55:233-60. [PMID: 17586317 DOI: 10.1016/s1054-3589(07)55007-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Richard Y Zhao
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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99
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Gershon E, Galiani D, Dekel N. Cytoplasmic polyadenylation controls cdc25B mRNA translation in rat oocytes resuming meiosis. Reproduction 2006; 132:21-31. [PMID: 16816330 DOI: 10.1530/rep.1.01093] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Resumption of meiosis in oocytes represents the entry into M-phase of the cell cycle and is regulated by the maturation-promoting factor (MPF). Activation of MPF is catalyzed by the dual specificity phosphatase, cdc25. In mammals, cdc25 is represented by a multigene family consisting of three isoforms: A, B and C. A recent report that female mice lacking cdc25B exhibit impaired fertility suggests a role for this isoform in regulating the G2- to M-transition in mammalian oocytes. Supporting the above-mentioned observation, we demonstrate herein that microinjection of neutralizing antibodies against cdc25B interfered with the ability of rat oocytes to undergo germinal vesicle breakdown (GVB). We also show accumulation of cdc25B in GVB oocytes and a transient reduction in its amount at metaphase I of meiosis. The accumulation of cdc25B was associated with its mRNA cytoplasmatic polyadenylation and was prevented by the protein synthesis inhibitor cyclohexamide as well as by the polyadenylation inhibitor cordycepin. Immunofluorescence staining revealed translocation of cdc25B to the metaphase II spindle apparatus. Taken together, our findings provide evidence that cdc25B is involved in resumption of meiosis in rat oocytes. We further demonstrate for the first time, a periodic accumulation of cdc25B throughout meiosis that is translationally regulated and involves cdc25B mRNA polyadenylation.
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Affiliation(s)
- Eran Gershon
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot, 76100 Israel
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100
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Trinkle-Mulcahy L, Lamond AI. Mitotic phosphatases: no longer silent partners. Curr Opin Cell Biol 2006; 18:623-31. [PMID: 17030123 DOI: 10.1016/j.ceb.2006.09.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Accepted: 09/29/2006] [Indexed: 11/18/2022]
Abstract
Recent work has highlighted the important role played by protein phosphatase complexes in the regulation of mitosis from yeast to mammals. There have been important advances in defining the roles of the protein serine/threonine phosphatases PP1 and PP2A and the dual specificity protein tyrosine phosphatases CDC25 and Cdc14. Three independent studies defined a regulatory role for PP2A in the control of sister chromatid cohesion, involving a direct interaction with shugoshin. A chromatin targeting subunit has been identified for PP1 and the complex shown to play an essential role in chromosome segregation. Key regulatory residues within CDC25 have been mapped and its activity tied both to the initial activation of cyclin-dependent kinases at the centrosome and to DNA damage checkpoints. Novel roles have been defined for Cdc14, including regulation of rDNA and telomere segregation and participation in spindle assembly. These exciting advances show that protein phosphatases are not merely silent partners to kinases in regulating the control of cell division.
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Affiliation(s)
- Laura Trinkle-Mulcahy
- Division of Gene Regulation & Expression, School of Life Sciences, University of Dundee, Dow St., Dundee DD1 5EH, UK.
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