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Journal articles on the topic 'CDC25Mm'

Author: Grafiati

Published: 9 March 2023

Last updated: 10 March 2023

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1

Ferguson, Angela M., Lynn S. White, Peter J. Donovan, and Helen Piwnica-Worms. "Normal Cell Cycle and Checkpoint Responses in Mice and Cells Lacking Cdc25B and Cdc25C Protein Phosphatases." Molecular and Cellular Biology 25, no. 7 (April 1, 2005): 2853–60. http://dx.doi.org/10.1128/mcb.25.7.2853-2860.2005.

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ABSTRACT The Cdc25 family of protein phosphatases positively regulates cell division by activating cyclin-dependent protein kinases (CDKs). In humans and rodents, there are three Cdc25 family members—denoted Cdc25A, Cdc25B, and Cdc25C—that can be distinguished based on their subcellular compartmentalizations, their abundances and/or activities throughout the cell cycle, the CDKs that they target for activation, and whether they are overexpressed in human cancers. In addition, murine forms of Cdc25 exhibit distinct patterns of expression throughout development and in adult tissues. These properties suggest that individual Cdc25 family members contribute distinct biological functions in embryonic and adult cell cycles of mammals. Interestingly, mice with Cdc25C disrupted are healthy, and cells derived from these mice exhibit normal cell cycles and checkpoint responses. Cdc25B − / − mice are also generally normal (although females are sterile), and cells derived from Cdc25B − / − mice have normal cell cycles. Here we report that mice lacking both Cdc25B and Cdc25C are obtained at the expected Mendelian ratios, indicating that Cdc25B and Cdc25C are not required for mouse development or mitotic entry. Furthermore, cell cycles, DNA damage responses, and Cdc25A regulation are normal in cells lacking Cdc25B and Cdc25C. These findings indicate that Cdc25A, or possibly other phosphatases, is able to functionally compensate for the loss of Cdc25B and Cdc25C in mice.

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2

Lammer, C., S. Wagerer, R. Saffrich, D. Mertens, W. Ansorge, and I. Hoffmann. "The cdc25B phosphatase is essential for the G2/M phase transition in human cells." Journal of Cell Science 111, no. 16 (August 15, 1998): 2445–53. http://dx.doi.org/10.1242/jcs.111.16.2445.

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Cdc25 phosphatases play key roles in cell cycle progression by activating cyclin-dependent kinases. In human cells, cdc25 proteins are encoded by a multigene family, consisting of cdc25A, cdc25B and cdc25C. While cdc25A plays a crucial role at the G1/S phase transition, cdc25C is involved in the dephosphorylation and activation of the mitotic kinase, cdc2/cyclinB. In addition, cdc25C itself is regulated by cdc2/cyclinB which then creates a positive feedback loop that controls entry into mitosis. In this study we show that the activity of cdc25B appears during late S phase and peaks during G2 phase. Both in vitro and in vivo cdc25B is activated through phosphorylation during S-phase. Using a cell duplication, microinjection assay we show that ablation of cdc25B function by specific antibodies blocks cell cycle progression in Hs68 cells by inhibition of entry into mitosis. Cdc25B function neither plays a role in later stages of mitosis nor for the inititation of DNA replication. These results indicate that cdc25B is a mitotic regulator that might act as a ‘starter phosphatase’ to initiate the positive feedback loop at the entry into M phase.

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3

Cen, H., A. G. Papageorge, W. C. Vass, K. E. Zhang, and D. R. Lowy. "Regulated and constitutive activity by CDC25Mm (GRF), a Ras-specific exchange factor." Molecular and Cellular Biology 13, no. 12 (December 1993): 7718–24. http://dx.doi.org/10.1128/mcb.13.12.7718-7724.1993.

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Serum stimulates cells to increase their proportion of Ras protein in the active GTP-bound state. We have recently identified four types (I to IV) of apparently full-length cDNAs from a single mammalian gene, called CDC25Mm or GRF, which is homologous to the Ras-specific exchange factor CDC25 of S. cerevisiae. The largest cDNA (type IV) is brain specific, with the other three classes, although they have distinct 5' ends, essentially representing progressive N-terminal deletions of this cDNA. When placed in a retroviral expression vector, all four types of cDNAs induced morphologic transformation of NIH 3T3 cells and an increase in the basal level of GTP.Ras. Serum stimulation of these transformants lead to a further increase in GTP.Ras only in cells expressing the type IV cDNA. Each type of GRF protein was found in cytosolic and membrane fractions, and the protein in each fraction could stimulate guanine nucleotide release from GDP.Ras in vitro. When NIH 3T3 cells and cells expressing the type IV protein were transfected with two versions of a mutant ras gene, one encoding membrane-associated Ras protein and the other encoding a cytosolic Ras protein, the basal levels of GTP bound to both forms of the mutant Ras protein were significantly higher in the cells expressing the type IV protein. However, serum increased the level of GTP bound to the membrane-associated mutant Ras protein in NIH 3T3 cells and in cells expressing the type IV protein but not in cells expressing the cytosolic version of the Ras protein. We conclude that each type of CDC25Mm induces cell transformation via the ability of its C terminus to stimulate guanine nucleotide exchange on Ras, the presence of N-terminal sequences is associated with a serum-dependent change in GTP.Ras, and the serum-dependent increase in GTP.Ras by exogenous CDC25Mm or by endogenous exchange factors probably requires membrane association of both Ras and the exchange factor.

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4

Cen, H., A. G. Papageorge, W. C. Vass, K. E. Zhang, and D. R. Lowy. "Regulated and constitutive activity by CDC25Mm (GRF), a Ras-specific exchange factor." Molecular and Cellular Biology 13, no. 12 (December 1993): 7718–24. http://dx.doi.org/10.1128/mcb.13.12.7718.

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Serum stimulates cells to increase their proportion of Ras protein in the active GTP-bound state. We have recently identified four types (I to IV) of apparently full-length cDNAs from a single mammalian gene, called CDC25Mm or GRF, which is homologous to the Ras-specific exchange factor CDC25 of S. cerevisiae. The largest cDNA (type IV) is brain specific, with the other three classes, although they have distinct 5' ends, essentially representing progressive N-terminal deletions of this cDNA. When placed in a retroviral expression vector, all four types of cDNAs induced morphologic transformation of NIH 3T3 cells and an increase in the basal level of GTP.Ras. Serum stimulation of these transformants lead to a further increase in GTP.Ras only in cells expressing the type IV cDNA. Each type of GRF protein was found in cytosolic and membrane fractions, and the protein in each fraction could stimulate guanine nucleotide release from GDP.Ras in vitro. When NIH 3T3 cells and cells expressing the type IV protein were transfected with two versions of a mutant ras gene, one encoding membrane-associated Ras protein and the other encoding a cytosolic Ras protein, the basal levels of GTP bound to both forms of the mutant Ras protein were significantly higher in the cells expressing the type IV protein. However, serum increased the level of GTP bound to the membrane-associated mutant Ras protein in NIH 3T3 cells and in cells expressing the type IV protein but not in cells expressing the cytosolic version of the Ras protein. We conclude that each type of CDC25Mm induces cell transformation via the ability of its C terminus to stimulate guanine nucleotide exchange on Ras, the presence of N-terminal sequences is associated with a serum-dependent change in GTP.Ras, and the serum-dependent increase in GTP.Ras by exogenous CDC25Mm or by endogenous exchange factors probably requires membrane association of both Ras and the exchange factor.

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5

Lindqvist, Arne, Helena Källström, Andreas Lundgren, Emad Barsoum, and Christina Karlsson Rosenthal. "Cdc25B cooperates with Cdc25A to induce mitosis but has a unique role in activating cyclin B1–Cdk1 at the centrosome." Journal of Cell Biology 171, no. 1 (October 10, 2005): 35–45. http://dx.doi.org/10.1083/jcb.200503066.

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Cdc25 phosphatases are essential for the activation of mitotic cyclin–Cdks, but the precise roles of the three mammalian isoforms (A, B, and C) are unclear. Using RNA interference to reduce the expression of each Cdc25 isoform in HeLa and HEK293 cells, we observed that Cdc25A and -B are both needed for mitotic entry, whereas Cdc25C alone cannot induce mitosis. We found that the G2 delay caused by small interfering RNA to Cdc25A or -B was accompanied by reduced activities of both cyclin B1–Cdk1 and cyclin A–Cdk2 complexes and a delayed accumulation of cyclin B1 protein. Further, three-dimensional time-lapse microscopy and quantification of Cdk1 phosphorylation versus cyclin B1 levels in individual cells revealed that Cdc25A and -B exert specific functions in the initiation of mitosis: Cdc25A may play a role in chromatin condensation, whereas Cdc25B specifically activates cyclin B1–Cdk1 on centrosomes.

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6

Wickramasinghe, D., S. Becker, M. K. Ernst, J. L. Resnick, J. M. Centanni, L. Tessarollo, L. B. Grabel, and P. J. Donovan. "Two CDC25 homologues are differentially expressed during mouse development." Development 121, no. 7 (July 1, 1995): 2047–56. http://dx.doi.org/10.1242/dev.121.7.2047.

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The cdc25 gene product is a tyrosine phosphatase that acts as an initiator of M-phase in eukaryotic cell cycles by activating p34cdc2. Here we describe the cloning and characterization of the developmental expression pattern of two mouse cdc25 homologs. Sequence comparison of the mouse genes with human CDC25 genes reveal that they are most likely the mouse homologs of human CDC25A and CDC25B respectively. Mouse cdc25a, which has not been described previously, shares 84% sequence identity with human CDC25A and has a highly conserved phosphatase domain characteristic of all cdc25 genes. A glutathione-S-transferase-cdc25a fusion protein can hydrolyze para-nitro-phenylphosphate confirming that cdc25a is a phosphatase. In adult mice, cdc25a transcripts are expressed at high levels in the testis and at lower levels in the ovary, particularly in germ cells; a pattern similar to that of twn, a Drosophila homolog of cdc25. Lower levels of transcript are also observed in kidney, liver, heart and muscle, a transcription pattern that partially overlaps, but is distinct from that of cdc25b. Similarly, in the postimplantation embryo cdc25a transcripts are expressed in a pattern that differs from that of cdc25b. cdc25a expression is observed in most developing embryonic organs while cdc25b expression is more restricted. An extended analysis of cdc25a and cdc25b expression in preimplantation embryos has also been carried out. These studies reveal that cdc25b transcripts are expressed in the one-cell embryo, decline at the two-cell stage and are re-expressed at the four-cell stage, following the switch from maternal to zygotic transcription which mirrors the expression of string, another Drosophila homolog of cdc25. In comparison, cdc25a is not expressed in the preimplantation embryo until the late blastocyst stage of development, correlating with the establishment of a more typical G1 phase in the embryonic cell cycles. Both cdc25a and cdc25b transcripts are expressed at high levels in the inner cell mass and the trophectoderm, which proliferate rapidly prior to implantation. These data suggest the cdc25 genes may have distinct roles in regulating the pattern of cell division during mouse embryogensis and gametogenesis.

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7

Chen, Mei-Shya, Jonathan Hurov, Lynn S. White, Terry Woodford-Thomas, and Helen Piwnica-Worms. "Absence of Apparent Phenotype in Mice Lacking Cdc25C Protein Phosphatase." Molecular and Cellular Biology 21, no. 12 (June 15, 2001): 3853–61. http://dx.doi.org/10.1128/mcb.21.12.3853-3861.2001.

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ABSTRACT The Cdc25 family of protein phosphatases positively regulate the cell division cycle by activating cyclin-dependent protein kinases. In humans and rodents, three Cdc25 family members denoted Cdc25A, -B, and -C have been identified. The murine forms of Cdc25 exhibit distinct patterns of expression both during development and in adult mouse tissues. In order to determine unique contributions made by the Cdc25C protein phosphatase to embryonic and adult cell cycles, mice lacking Cdc25C were generated. We report thatCdc25C −/− mice are viable and do not display any obvious abnormalities. Among adult tissues in whichCdc25C is detected, its transcripts are most abundant in testis, followed by thymus, ovary, spleen, and intestine. Mice lackingCdc25C were fertile, indicating that Cdc25Cdoes not contribute an essential function during spermatogenesis or oogenesis in the mouse. T- and B-cell development was also found to be normal in Cdc25C −/− mice, andCdc25C −/− mouse splenic T and B cells exhibited normal proliferative responses in vitro. Finally, the phosphorylation status of Cdc2, the timing of entry into mitosis, and the cellular response to DNA damage were unperturbed in mouse embryo fibroblasts lacking Cdc25C. These findings indicate thatCdc25A and/or Cdc25B may compensate for loss ofCdc25C in the mouse.

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8

Jacquet, Eric, Soria Baouz, and Andrea Parmeggiani. "Characterization of mammalian C-CDC25Mm exchange factor and kinetic properties of the exchange reaction intermediate p21.cntdot.C-CDC25Mm." Biochemistry 34, no. 38 (September 1995): 12347–54. http://dx.doi.org/10.1021/bi00038a031.

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9

Zhou, Xiaokun, Danping Lu, Wenxiang Yi, and Dan Xu. "Downregulation of CDC25C in NPCs Disturbed Cortical Neurogenesis." International Journal of Molecular Sciences 24, no. 2 (January 12, 2023): 1505. http://dx.doi.org/10.3390/ijms24021505.

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Cell division regulators play a vital role in neural progenitor cell (NPC) proliferation and differentiation. Cell division cycle 25C (CDC25C) is a member of the CDC25 family of phosphatases which positively regulate cell division by activating cyclin-dependent protein kinases (CDKs). However, mice with the Cdc25c gene knocked out were shown to be viable and lacked the apparent phenotype due to genetic compensation by Cdc25a and/or Cdc25b. Here, we investigate the function of Cdc25c in developing rat brains by knocking down Cdc25c in NPCs using in utero electroporation. Our results indicate that Cdc25c plays an essential role in maintaining the proliferative state of NPCs during cortical development. The knockdown of Cdc25c causes early cell cycle exit and the premature differentiation of NPCs. Our study uncovers a novel role of CDC25C in NPC division and cell fate determination. In addition, our study presents a functional approach to studying the role of genes, which elicit genetic compensation with knockout, in cortical neurogenesis by knocking down in vivo.

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10

Kang, Min, Aera Bang, Ok Choi, and Seung Han. "Comparative analysis of two murine CDC25B isoforms." Archives of Biological Sciences 69, no. 1 (2017): 35–44. http://dx.doi.org/10.2298/abs160315062k.

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CDC25B phosphatase plays a pivotal role in the cell cycle process by dephosphorylating and activating the CDC2 kinase of maturation-promoting factor (MPF). In mice, two transcripts of Cdc25B are generated by the alternative splicing of one gene. We compared the properties of these two forms of CDC25B. When the expression pattern of Cdc25B was examined using RT-PCR, both forms were detected in almost all mouse tissues tested. The expression of two forms of the CDC25B protein in various mouse tissues was confirmed using Western blotting with generated isoform specific antibodies. CDC25B1 tends to accumulate more in the cytosol than CDC25B2 does, and they have different binding capacity for 14-3-3 proteins. CDC25B1 was more effective in dephosphorylating in vitro substrate para-nitrophenyl phosphate and showed higher activity in the modified histone H1 kinase assay than CDC25B2. These results suggest that the two forms of CDC25B play different roles in cell cycle regulation.

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11

Nishijima, Hitoshi, Hideo Nishitani, Takashi Seki, and Takeharu Nishimoto. "A Dual-Specificity Phosphatase Cdc25B Is an Unstable Protein and Triggers p34cdc2/Cyclin B Activation in Hamster BHK21 Cells Arrested with Hydroxyurea." Journal of Cell Biology 138, no. 5 (September 8, 1997): 1105–16. http://dx.doi.org/10.1083/jcb.138.5.1105.

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By incubating at 30°C in the presence of an energy source, p34cdc2/cyclin B was activated in the extract prepared from a temperature-sensitive mutant, tsBN2, which prematurely enters mitosis at 40°C, the nonpermissive temperature (Nishimoto, T., E. Eilen, and C. Basilico. 1978. Cell. 15:475–483), and wild-type cells of the hamster BHK21 cell line arrested in S phase, without protein synthesis. Such an in vitro activation of p34cdc2/cyclin B, however, did not occur in the extract prepared from cells pretreated with protein synthesis inhibitor cycloheximide, although this extract still retained the ability to inhibit p34cdc2/cyclin B activation. When tsBN2 cells arrested in S phase were incubated at 40°C in the presence of cycloheximide, Cdc25B, but not Cdc25A and C, among a family of dual-specificity phosphatases, Cdc25, was lost coincidentally with the lack of the activation of p34cdc2/cyclin B. Consistently, the immunodepletion of Cdc25B from the extract inhibited the activation of p34cdc2/cyclin B. Cdc25B was found to be unstable (half-life < 30 min). Cdc25B, but not Cdc25C, immunoprecipitated from the extract directly activated the p34cdc2/cyclin B of cycloheximide-treated cells as well as that of nontreated cells, although Cdc25C immunoprecipitated from the extract of mitotic cells activated the p34cdc2/cyclin B within the extract of cycloheximide-treated cells. Our data suggest that Cdc25B made an initial activation of p34cdc2/cyclin B, which initiates mitosis through the activation of Cdc25C.

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12

Blomberg, Ida, and Ingrid Hoffmann. "Ectopic Expression of Cdc25A Accelerates the G1/S Transition and Leads to Premature Activation of Cyclin E- and Cyclin A-Dependent Kinases." Molecular and Cellular Biology 19, no. 9 (September 1, 1999): 6183–94. http://dx.doi.org/10.1128/mcb.19.9.6183.

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ABSTRACT Human Cdc25 phosphatases play important roles in cell cycle regulation by removing inhibitory phosphates from tyrosine and threonine residues of cyclin-dependent kinases. Three human Cdc25 isoforms, A, B, and C, have been discovered. Cdc25B and Cdc25C play crucial roles at the G2/M transition. In the present study, we have investigated the function of human Cdc25A phosphatase. Cell lines that express human Cdc25A in an inducible manner have been generated. Ectopic expression of Cdc25A accelerates the G1/S-phase transition, indicating that Cdc25A controls an event(s) that is rate limiting for entry into S phase. Furthermore, we carried out a detailed analysis of the expression and activation of human Cdc25A. Activation of endogenous Cdc25A occurs during late G1 phase and increases in S and G2 phases. We further demonstrate that Cdc25A is activated at the same time as cyclin E- and cyclin A-dependent kinases. In vitro, Cdc25A dephosphorylates and activates the cyclin-Cdk complexes that are active during G1. Overexpression of Cdc25A in the inducible system, however, leads to a premature activation of both cyclin E-Cdk2 and cyclin A-Cdk2 complexes, while no effect of cyclin D-dependent kinases is observed. Furthermore, Cdc25A overexpression induces a tyrosine dephosphorylation of Cdk2. These results suggest that Cdc25A is an important regulator of the G1/S-phase transition and that cyclin E- and cyclin A-dependent kinases act as direct targets.

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13

Innocenti, Metello, Renata Zippel, Riccardo Brambilla, and Emmapaola Sturani. "CDC25Mm /Ras-GRF1 regulates both Ras and Rac signaling pathways." FEBS Letters 460, no. 2 (October 25, 1999): 357–62. http://dx.doi.org/10.1016/s0014-5793(99)01374-5.

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14

Mattingly, Raymond R., Vijay Saini, and Ian G. Macara. "Activation of the Ras-GRF/CDC25Mm Exchange Factor by Lysophosphatidic Acid." Cellular Signalling 11, no. 8 (August 1999): 603–10. http://dx.doi.org/10.1016/s0898-6568(99)00034-0.

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15

Coccetti, P., I. Mauri, L. Alberghina, E. Martegani, and A. Parmeggiani. "The Minimal Active Domain of the Mouse Ras Exchange Factor CDC25Mm." Biochemical and Biophysical Research Communications 206, no. 1 (January 1995): 253–59. http://dx.doi.org/10.1006/bbrc.1995.1035.

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16

Turowski, Patric, Celine Franckhauser, May C. Morris, Philippe Vaglio, Anne Fernandez, and Ned J. C. Lamb. "Functional cdc25C Dual-Specificity Phosphatase Is Required for S-Phase Entry in Human Cells." Molecular Biology of the Cell 14, no. 7 (July 2003): 2984–98. http://dx.doi.org/10.1091/mbc.e02-08-0515.

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In view of the common regulatory mechanism that induces transcription of the mitotic phosphatase cdc25C and cyclin A at the beginning of S-phase, we investigated whether cdc25C was required for S-phase transit. Here, we show that in both nontransformed human fibroblasts and HeLa cells, cdc25C protein levels significantly increased concomitant with S-phase onset and cyclin A synthesis. Activity measurements on immunoprecipitates from synchronized HeLa cells revealed a sharp rise in cdc25C-associated phosphatase activity that coincided with S-phase. Microinjection of various antisense-cdc25C molecules led to inhibition of DNA synthesis in both HeLa cells and human fibroblasts. Furthermore, transfection of small interfering RNA directed against cdc25C specifically depleted cdc25C in HeLa cells without affecting cdc25A or cdc25B levels. Cdc25C RNA interference was also accompanied by S-phase inhibition. In cells depleted of cdc25C by antisense or siRNA, normal cell cycle progression could be re-established through microinjection of wild-type cdc25C protein but not inactive C377S mutant protein. Taken together, these results show that cdc25C not only plays a role at the G2/M transition but also in the modulation of DNA replication where its function is distinct from that of cdc25A.

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17

Kiyono, M., T. Satoh, and Y. Kaziro. "G protein subunit-dependent Rac-guanine nucleotide exchange activity of Ras-GRF1/CDC25Mm." Proceedings of the National Academy of Sciences 96, no. 9 (April 27, 1999): 4826–31. http://dx.doi.org/10.1073/pnas.96.9.4826.

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18

Tonini, Raffaella, Silvana Franceschetti, Daniela Parolaro, Mariaelvina Sala, Enzo Mancinelli, Silvia Tininini, Ronny Brusetti, et al. "Involvement of CDC25Mm/Ras-GRF1-Dependent Signaling in the Control of Neuronal Excitability." Molecular and Cellular Neuroscience 18, no. 6 (December 2001): 691–701. http://dx.doi.org/10.1006/mcne.2001.1050.

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19

Sturani, Emmapaola, Adele Abbondio, Paola Branduardi, Cristina Ferrari, Renata Zippel, Enzo Martegani, Marco Vanoni, and Suzanne Denis-Donini. "The Ras Guanine Nucleotide Exchange Factor CDC25Mm Is Present at the Synaptic Junction." Experimental Cell Research 235, no. 1 (August 1997): 117–23. http://dx.doi.org/10.1006/excr.1997.3660.

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20

Coccetti, Paola, Enrico Monzani, Lilia Alberghina, Luigi Casella, and Enzo Martegani. "Analysis of the secondary structure of the catalytic domain of mouse Ras exchange factor CDC25Mm." Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology 1383, no. 2 (April 1998): 292–300. http://dx.doi.org/10.1016/s0167-4838(97)00212-4.

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21

Consonni, Roberto, Ivana Arosio, Teresa Recca, Renato Longhi, Giorgio Colombo, and Marco Vanoni. "Structure Determination and Dynamics of Peptides Overlapping the Catalytic Hairpin of the Ras-Specific GEF Cdc25Mm†." Biochemistry 42, no. 42 (October 2003): 12154–62. http://dx.doi.org/10.1021/bi0344026.

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22

Vanoni, Marco, Riccardo Bertini, Elena Sacco, Laura Fontanella, Monica Rieppi, Sonia Colombo, Enzo Martegani, et al. "Characterization and Properties of Dominant-negative Mutants of the Ras-specific Guanine Nucleotide Exchange Factor CDC25Mm." Journal of Biological Chemistry 274, no. 51 (December 17, 1999): 36656–62. http://dx.doi.org/10.1074/jbc.274.51.36656.

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23

Ferrari, C., R. Zippel, E. Martegani, N. Gnesutta, V. Carrera, and E. Sturani. "Expression of Two Different Products of CDC25Mm, a Mammalian Ras Activator, during Development of Mouse Brain." Experimental Cell Research 210, no. 2 (February 1994): 353–57. http://dx.doi.org/10.1006/excr.1994.1048.

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24

Karlsson, Christina, Stephanie Katich, Anja Hagting, Ingrid Hoffmann, and Jonathon Pines. "Cdc25b and Cdc25c Differ Markedly in Their Properties as Initiators of Mitosis." Journal of Cell Biology 146, no. 3 (August 9, 1999): 573–84. http://dx.doi.org/10.1083/jcb.146.3.573.

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We have used time-lapse fluorescence microscopy to study the properties of the Cdc25B and Cdc25C phosphatases that have both been implicated as initiators of mitosis in human cells. To differentiate between the functions of the two proteins, we have microinjected expression constructs encoding Cdc25B or Cdc25C or their GFP-chimeras into synchronized tissue culture cells. This assay allows us to express the proteins at defined points in the cell cycle. We have followed the microinjected cells by time-lapse microscopy, in the presence or absence of DNA synthesis inhibitors, and assayed whether they enter mitosis prematurely or at the correct time. We find that overexpressing Cdc25B alone rapidly causes S phase and G2 phase cells to enter mitosis, whether or not DNA replication is complete, whereas overexpressing Cdc25C does not cause premature mitosis. Overexpressing Cdc25C together with cyclin B1 does shorten the G2 phase and can override the unreplicated DNA checkpoint, but much less efficiently than overexpressing Cdc25B. These results suggest that Cdc25B and Cdc25C do not respond identically to the same cell cycle checkpoints. This difference may be related to the differential localization of the proteins; Cdc25C is nuclear throughout interphase, whereas Cdc25B is nuclear in the G1 phase and cytoplasmic in the S and G2 phases. We have found that the change in subcellular localization of Cdc25B is due to nuclear export and that this is dependent on cyclin B1. Our data suggest that although both Cdc25B and Cdc25C can promote mitosis, they are likely to have distinct roles in the controlling the initiation of mitosis.

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25

Baouz, Soria, Eric Jacquet, Katia Accorsi, Codjo Hountondji, Monica Balestrini, Renata Zippel, Emmapaola Sturani, and Andrea Parmeggiani. "Sites of Phosphorylation by Protein Kinase A in CDC25Mm/GRF1, a Guanine Nucleotide Exchange Factor for Ras." Journal of Biological Chemistry 276, no. 3 (October 3, 2000): 1742–49. http://dx.doi.org/10.1074/jbc.m005770200.

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26

Gariboldi, Manuela, Emmapaola Sturani, Federico Canzian, Laura De Gregorio, Giacomo Manenti, Tommaso A. Dragani, and Marco A. Pierotti. "Genetic Mapping of the Mouse CDC25Mm Gene, a Ras-Specific Guanine Nucleotide-Releasing Factor, to Chromosome 9." Genomics 21, no. 2 (May 1994): 451–53. http://dx.doi.org/10.1006/geno.1994.1295.

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27

List, Alan F., Kathy Rocha, Ling Zhang, Rami S. Komrokji, Justine Clark, Gisela Caceres, Debbie Billingsley, et al. "Secondary Resistance to Lenalidomide in Del(5q) MDS Is Associated with CDC25C & PP2A Overexpression." Blood 114, no. 22 (November 20, 2009): 292. http://dx.doi.org/10.1182/blood.v114.22.292.292.

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Abstract Abstract 292 Background: Allelic deficiency for the RPS14 gene impairs differentiation and survival of erythroid progenitors in del(5q) MDS (Nature 2008; 451:335). Nucleolar stress arising from disruption of ribosome assembly fosters MDM2 sequestration by free ribosome components resulting in p53 stabilization and erythroid hypoplasia (Nat Cell Biol 2009; 11:501). We recently reported that reduced gene dosage of the lenalidomide (LEN) inhibitable, haplodeficient phosphatases CDC25C and PP2Acα is a key determinant of drug sensitivity in del(5q) MDS (PNAS 2009; 106: 12974). We now show that shRNA suppression of these genes to levels commensurate with haplodeficiency reinforces p53 accumulation, and that treatment with LEN promotes MDM2-mediated p53 degradation to transition del(5q) clones to G2/M arrest. We hypothesized that emergence of resistance to LEN in del(5q) MDS arises from two possible mechanisms: (1) up-regulation of haplodeficient drug targets or compensatory isotypes, or (2) inactivating mutations of the TP53 or CDC25C genes. Methods: To investigate mechanisms of LEN resistance, we studied sequential bone marrow (BM) specimens obtained at baseline (BL), response to treatment (TR) and treatment failure (TF) from 12 LEN treated patients with Low/INT-1 risk, transfusion-dependent del(5q) MDS. Eleven patients achieved clonal suppression and transfusion independence; 7 patients developed clinical drug resistance with primary clonal recovery. Immunohistochemical (IHC) staining for cdc25-C, -A and -B; PP2A–Ca and p53 were performed using a biotin-streptavidin-horseradish peroxidase method and compared to 6 age-matched controls; intensity of cytoplasmic or nuclear staining in hematopoietic elements was recorded after blinded review. DNA and RNA were extracted from cryopreserved BM mononuclear cells (BM-MNC) or fixed paraffin blocks from BM clot and biopsy sections. Expression of CDC25C splice variants was assessed by RT-PCR and total gene expression by real time (QT)-PCR. Exonic DNA encoding the catalytic [exons 8–14] and nuclear export domains [exon 11] of CDC25C and the DNA-binding domain of TP53 [exons 4–9] was sequenced for gene mutation analysis. Differences in mean values were compared by paired t-test. Results: P53 immunostaining was significantly higher in del(5q) BL specimens compared to controls ( relative expression [RE] 9.6 vs. 0.25; P =0.007). An admixture of nuclear and cytoplasmic staining for p53 and each cdc25 isotype was observed at BL that was largely restricted to erythroid precursors, whereas at TR cdc25-C and -A expression was primarily cytoplasmic, consistent with drug-induced nuclear exclusion. At TR, RE of only cdc25C (BL, 75 vs. TR, 49; P=0.05) and PP2A (29.2 vs. 12.3; P=0.025) was significantly reduced; whereas at TF cdc25C (TR, 43 vs. TF, 166; P=0.003), cdc25A (42.4 vs. 150; P=0.006), PP2A (7.3 vs. 65.6; P=0.028) and p53 (0.92 vs. 25.4; P=0.024) RE significantly increased. Nuclear localization of cdc25C and p53 but not cdc25A predominated at TF, consistent with escape from cdc25C inhibition. QT-PCR confirmed transcriptional up-regulation of CDC25C at TF with a mean 8.8-fold increase in gene expression vs. BL. DNA sequencing revealed no acquisition of somatic mutations within the CDC25C and TP53 exons studied [n=5]. Conclusions: Secondary resistance to LEN in del(5q) MDS is associated with over-expression and activation of the haplodeficient drug-inhibitable phosphatases, cdc25C and PP2A, with consequent restoration of wt-p53 activation. Absence of gene mutations within the coding exons analyzed suggests that transcriptional compensation alone is responsible for drug resistance. Novel agents targeting transcriptional repression of CDC25C may restore LEN sensitivity and merit investigation in drug resistant del(5q) MDS. Disclosures: List: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Komrokji:Celgene: Research Funding, Speakers Bureau. Lancet:Celgene: Research Funding. Maciejewski:Esai: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

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Lee, M. S., S. Ogg, M. Xu, L. L. Parker, D. J. Donoghue, J. L. Maller, and H. Piwnica-Worms. "cdc25+ encodes a protein phosphatase that dephosphorylates p34cdc2." Molecular Biology of the Cell 3, no. 1 (January 1992): 73–84. http://dx.doi.org/10.1091/mbc.3.1.73.

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To determine how the human cdc25 gene product acts to regulate p34cdc2 at the G2 to M transition, we have overproduced the full-length protein (cdc25Hs) as well as several deletion mutants in bacteria as glutathione-S-transferase fusion proteins. The wild-type cdc25Hs gene product was synthesized as an 80-kDa fusion protein (p80GST-cdc25) and was judged to be functional by several criteria: recombinant p80GST-cdc25 induced meiotic maturation of Xenopus oocytes in the presence of cycloheximide; p80GST-cdc25 activated histone H1 kinase activity upon addition to extracts prepared from Xenopus oocytes; p80GST-cdc25 activated p34cdc2/cyclin B complexes (prematuration promoting factor) in immune complex kinase assays performed in vitro; p80GST-cdc25 stimulated the tyrosine dephosphorylation of p34cdc2/cyclin complexes isolated from Xenopus oocyte extracts as well as from overproducing insect cells; and p80GST-cdc25 hydrolyzed p-nitrophenylphosphate. In addition, deletion analysis defined a functional domain residing within the carboxy-terminus of the cdc25Hs protein. Taken together, these results suggest that the cdc25Hs protein is itself a phosphatase and that it may function directly in the tyrosine dephosphorylation and activation of p34cdc2 at the G2 to M transition.

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Mattingly, Raymond R., and Ian G. Macara. "Phosphorylation-dependent activation of the Ras-GRF/CDC25Mm exchange factor by muscarinic receptors and G-protein βγ subunits." Nature 382, no. 6588 (July 1996): 268–72. http://dx.doi.org/10.1038/382268a0.

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Gabrielli, B. G., C. P. De Souza, I. D. Tonks, J. M. Clark, N. K. Hayward, and K. A. Ellem. "Cytoplasmic accumulation of cdc25B phosphatase in mitosis triggers centrosomal microtubule nucleation in HeLa cells." Journal of Cell Science 109, no. 5 (May 1, 1996): 1081–93. http://dx.doi.org/10.1242/jcs.109.5.1081.

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The formation of the mitotic spindle is an essential prerequisite for successful mitosis. The dramatic changes in the level of microtubule (Mt) nucleation at the centrosomes and Mt dynamics that occur in prophase are presumed to be initiated through the activity of cdc2/cyclin B. Here we present data that the cdc25B isoform functions to activate the cytoplasmic pool of cdc2/cyclin B responsible for these events. In contrast to cdc25C, cdc25B is present at low levels in HeLa cells during interphase, but sharply increases in prophase, when cdc25B accumulation in the cytoplasm correlates with prophase spindle formation. Overexpression of wild type and dominant negative mutants of cdc25B and cdc25C shows that prophase Mt nucleation is a consequence of cytoplasmic cdc25B activity, and that cdc25C regulates nuclear G2/M events. Our data also suggest that the functional status of the centrosome can regulate nuclear mitotic events.

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31

Jones, S., M. L. Vignais, and J. R. Broach. "The CDC25 protein of Saccharomyces cerevisiae promotes exchange of guanine nucleotides bound to ras." Molecular and Cellular Biology 11, no. 5 (May 1991): 2641–46. http://dx.doi.org/10.1128/mcb.11.5.2641-2646.1991.

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The product of the CDC25 gene of Saccharomyces cerevisiae, in its capacity as an activator of the RAS/cyclic AMP pathway, is required for initiation of the cell cycle. In this report, we provide an identification of Cdc25p, the product of the CDC25 gene, and evidence that it promotes exchange of guanine nucleotides bound to Ras in vitro. Extracts of strains containing high levels of Cdc25p catalyze both removal of GDP from and the concurrent binding of GTP to Ras. This same activity is also obtained with an immunopurified Cdc25p-beta-galactosidase fusion protein, suggesting that Cdc25p participates directly in the exchange reaction. This biochemical activity is consistent with previous genetic analysis of CDC25 function.

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32

Jones, S., M. L. Vignais, and J. R. Broach. "The CDC25 protein of Saccharomyces cerevisiae promotes exchange of guanine nucleotides bound to ras." Molecular and Cellular Biology 11, no. 5 (May 1991): 2641–46. http://dx.doi.org/10.1128/mcb.11.5.2641.

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The product of the CDC25 gene of Saccharomyces cerevisiae, in its capacity as an activator of the RAS/cyclic AMP pathway, is required for initiation of the cell cycle. In this report, we provide an identification of Cdc25p, the product of the CDC25 gene, and evidence that it promotes exchange of guanine nucleotides bound to Ras in vitro. Extracts of strains containing high levels of Cdc25p catalyze both removal of GDP from and the concurrent binding of GTP to Ras. This same activity is also obtained with an immunopurified Cdc25p-beta-galactosidase fusion protein, suggesting that Cdc25p participates directly in the exchange reaction. This biochemical activity is consistent with previous genetic analysis of CDC25 function.

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33

Lenzen, Christian, Robbert H. Cool, Heino Prinz, Jürgen Kuhlmann, and Alfred Wittinghofer. "Kinetic Analysis by Fluorescence of the Interaction between Ras and the Catalytic Domain of the Guanine Nucleotide Exchange Factor Cdc25Mm †." Biochemistry 37, no. 20 (May 1998): 7420–30. http://dx.doi.org/10.1021/bi972621j.

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34

Giglione, Carmela, Stefania Gonfloni, and Andrea Parmeggiani. "Differential actions of p60c-Src and Lck kinases on the Ras regulators p120-GAP and GDP/GTP exchange factor CDC25Mm." European Journal of Biochemistry 268, no. 11 (June 1, 2001): 3275–83. http://dx.doi.org/10.1046/j.1432-1327.2001.02230.x.

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35

Baouz, Soria, Eric Jacquet, Alberto Bernardi, and Andrea Parmeggiani. "The N-terminal Moiety of CDC25Mm, a GDP/GTP Exchange Factor of Ras Proteins, Controls the Activity of the Catalytic Domain." Journal of Biological Chemistry 272, no. 10 (March 7, 1997): 6671–76. http://dx.doi.org/10.1074/jbc.272.10.6671.

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36

Gnesutta, Nerina, Michela Ceriani, Metello Innocenti, Isabella Mauri, Renata Zippel, Emmapaola Sturani, Barbara Borgonovo, Giovanna Berruti, and Enzo Martegani. "Cloning and Characterization of Mouse UBPy, a Deubiquitinating Enzyme That Interacts with the Ras Guanine Nucleotide Exchange Factor CDC25Mm/Ras-GRF1." Journal of Biological Chemistry 276, no. 42 (August 10, 2001): 39448–54. http://dx.doi.org/10.1074/jbc.m103454200.

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Gershon, Eran, Dalia Galiani, and Nava Dekel. "Cytoplasmic polyadenylation controls cdc25B mRNA translation in rat oocytes resuming meiosis." Reproduction 132, no. 1 (July 2006): 21–31. http://dx.doi.org/10.1530/rep.1.01093.

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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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Hernández, Silvia, Luis Hernández, Sílvia Bea, Magda Pinyol, Iracema Nayach, Beatriz Bellosillo, Alfons Nadal, et al. "cdc25a and the splicing variant cdc25b2, but not cdc25B1, -B3 or -C, are over-expressed in aggressive human non-Hodgkin's lymphomas." International Journal of Cancer 89, no. 2 (March 20, 2000): 148–52. http://dx.doi.org/10.1002/(sici)1097-0215(20000320)89:2<148::aid-ijc8>3.0.co;2-r.

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39

Demetrick, Douglas J., and David H. Beach. "Chromosome Mapping of Human CDC25A and CDC25B Phosphatases." Genomics 18, no. 1 (October 1993): 144–47. http://dx.doi.org/10.1006/geno.1993.1440.

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40

Ito, Y., H. Yoshida, K. Nakano, K. Kobayashi, T. Yokozawa, K. Hirai, F. Matsuzuka, et al. "Expression of cdc25A and cdc25B proteins in thyroid neoplasms." British Journal of Cancer 86, no. 12 (June 2002): 1909–13. http://dx.doi.org/10.1038/sj.bjc.6600364.

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41

Ito, Yasuhiro, Hiroshi Yoshida, Takashi Uruno, Yuuki Takamura, Akihiro Miya, Kanji Kuma, and Akira Miyauchi. "Expression of cdc25A and cdc25B phosphatase in breast carcinoma." Breast Cancer 11, no. 3 (August 2004): 295–300. http://dx.doi.org/10.1007/bf02984552.

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42

Shreeram, Sathyavageeswaran, Weng Kee Hee, and Dmitry V. Bulavin. "Cdc25A Serine 123 Phosphorylation Couples Centrosome Duplication with DNA Replication and Regulates Tumorigenesis." Molecular and Cellular Biology 28, no. 24 (October 20, 2008): 7442–50. http://dx.doi.org/10.1128/mcb.00138-08.

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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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Fernandez-Vidal, Anne, Anne Mazars, and Stephane Manenti. "CDC25A: A Rebel Within the CDC25 Phosphatases Family?" Anti-Cancer Agents in Medicinal Chemistry 8, no. 8 (December 1, 2008): 825–31. http://dx.doi.org/10.2174/187152008786847684.

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44

Boy-Marcotte, E., P. Ikonomi, and M. Jacquet. "SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation." Molecular Biology of the Cell 7, no. 4 (April 1996): 529–39. http://dx.doi.org/10.1091/mbc.7.4.529.

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The SDC25 gene of Saccharomyces cerevisiae is homologous to CDC25. Its 3' domain encodes a guanine nucleotide exchange factor (GEF) for Ras. Nevertheless, the GEF encoded by CDC24 is determinant for the Ras/cAMP pathway activation in growth. We demonstrate that the SDC25 gene product is a functional GEF for Ras: the complete SDC25 gene functionally replaces CDC25 when overexpressed or when transcribed under CDC25 transcriptional control at the CDC25 locus. Chimeric proteins between Sdc25p and Cdc25p are also functional GEFs for Ras. We also show that the two genes are differentially regulated: SDC25 is not transcribed at a detectable level in growth conditions when glucose is the carbon source. It is transcribed at the end of growth when nutrients are depleted and in cells grown on nonfermentable carbon sources. In contrast, CDC25 accumulation is slightly reduced when glucose is replaced by a nonfermentable carbon source.

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45

Carrera, Vittorio, Andrea Moroni, Enzo Martegani, Celina Volponi, Robbert H. Cool, Lilia Alberghina, and Marco Vanoni. "Mutations at position 1122 in the catalytic domain of the mouse ras-specific guanine nucleotide exchange factor CDC25Mm originate both loss-of-function and gain-of-function proteins." FEBS Letters 440, no. 3 (December 4, 1998): 291–96. http://dx.doi.org/10.1016/s0014-5793(98)01481-1.

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46

Margolis, Seth S., Jennifer A. Perry, Douglas H. Weitzel, Christopher D. Freel, Minoru Yoshida, Timothy A. Haystead, and Sally Kornbluth. "A Role for PP1 in the Cdc2/Cyclin B–mediated Positive Feedback Activation of Cdc25." Molecular Biology of the Cell 17, no. 4 (April 2006): 1779–89. http://dx.doi.org/10.1091/mbc.e05-08-0751.

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The Cdc25 phosphatase promotes entry into mitosis through the removal of inhibitory phosphorylations on the Cdc2 subunit of the Cdc2/CyclinB complex. During interphase, or after DNA damage, Cdc25 is suppressed by phosphorylation at Ser287 (Xenopus numbering; Ser216 of human Cdc25C) and subsequent binding of the small acidic protein, 14-3-3. As reported recently, at the time of mitotic entry, 14-3-3 protein is removed from Cdc25 and S287 is dephosphorylated by protein phosphatase 1 (PP1). After the initial activation of Cdc25 and consequent derepression of Cdc2/CyclinB, Cdc25 is further activated through a Cdc2-catalyzed positive feedback loop. Although the existence of such a loop has been appreciated for some time, the molecular mechanism for this activation has not been described. We report here that phosphorylation of S285 by Cdc2 greatly enhances recruitment of PP1 to Cdc25, thereby accelerating S287 dephosphorylation and mitotic entry. Moreover, we show that two other previously reported sites of Cdc2-catalyzed phosphorylation on Cdc25 are required for maximal biological activity of Cdc25, but they do not contribute to PP1 regulation and do not act solely through controlling S287 phosphorylation. Therefore, multiple mechanisms, including enhanced recruitment of PP1, are used to promote full activation of Cdc25 at the time of mitotic entry.

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Ito, Yasuhiro, Hiroshi Yoshida, Chisato Tomoda, Takashi Uruno, Yuuki Takamura, Akihiro Miya, Kaoru Kobayashi, et al. "Expression of cdc25B and cdc25A in medullary thyroid carcinoma: cdc25B expression level predicts a poor prognosis." Cancer Letters 229, no. 2 (November 2005): 291–97. http://dx.doi.org/10.1016/j.canlet.2005.06.040.

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48

Izumi, T., and J. L. Maller. "Phosphorylation and activation of the Xenopus Cdc25 phosphatase in the absence of Cdc2 and Cdk2 kinase activity." Molecular Biology of the Cell 6, no. 2 (February 1995): 215–26. http://dx.doi.org/10.1091/mbc.6.2.215.

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The M-phase inducer, Cdc25C, is a dual-specificity phosphatase that directly phosphorylates and activates the cyclin B/Cdc2 kinase complex, leading to initiation of mitosis. Cdc25 itself is activated at the G2/M transition by phosphorylation on serine and threonine residues. Previously, it was demonstrated that Cdc2 kinase is capable of phosphorylating and activating Cdc25, suggesting the existence of a positive feedback loop. In the present study, kinases other than Cdc2 that can phosphorylate and activate Cdc25 were investigated. Cdc25 was found to be phosphorylated and activated by cyclin A/Cdk2 and cyclin E/Cdk2 in vitro. However, in interphase Xenopus egg extracts with no detectable Cdc2 and Cdk2, treatment with the phosphatase inhibitor microcystin activated a distinct kinase that could phosphorylate and activate Cdc25. Microcystin also induced other mitotic phenomena such as chromosome condensation and nuclear envelope breakdown in extracts containing less than 5% of the mitotic level of Cdc2 kinase activity. These findings implicate a kinase other than Cdc2 and Cdk2 that may initially activate Cdc25 in vivo and suggest that this kinase may also phosphorylate M-phase substrates even in the absence of Cdc2 kinase.

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Folch-Mallol, Jorge Luis, Luz María Martínez, Sergio J. Casas, Runying Yang, Claudia Martínez-Anaya, Lorena López, Alejandra Hernández, and Jorge Nieto-Sotelo. "New roles for CDC25 in growth control, galactose regulation and cellular differentiation in Saccharomyces cerevisiae." Microbiology 150, no. 9 (September 1, 2004): 2865–79. http://dx.doi.org/10.1099/mic.0.27144-0.

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Living organisms display large differences in stress resistance throughout their life cycles. To study the coordinated regulation of development and stress responses in exponentially growing yeast, mutants that displayed elevated heat-shock resistance at this stage were screened for. Here, two new mutant alleles of CDC25 in Saccharomyces cerevisiae, cdc25-21 and cdc25-22, are described. During exponential growth in glucose at 25 °C, these mutants are resistant to heat, oxidative, osmotic and ionic shock, accumulate stress-protein transcripts, show slow growth rates, thick cell walls and glycogen hyperaccumulation and lack cAMP signalling in response to glucose. Genetic and cellular analyses revealed that the stationary-phase phenotypes of cdc25-21 and cdc25-22 mutants are not due to entrance to a G0 state during exponential growth, but are the result of a prolonged G1 phase. It was found that, in the W303 background, CDC25 is dispensable for growth in glucose media. However, CDC25 is essential for growth in galactose, in non-fermentable carbon sources and under continuous incubation at 38 °C. In conclusion, the function of the catalytic, C-terminal domain of Cdc25p is not only important for fermentative growth, but also for growth in non-fermentable carbon sources and to trigger galactose derepression.

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Al‐Matouq, Jenan, Thomas R. Holmes, and Laura A. Hansen. "CDC25B and CDC25C overexpression in nonmelanoma skin cancer suppresses cell death." Molecular Carcinogenesis 58, no. 9 (June 24, 2019): 1691–700. http://dx.doi.org/10.1002/mc.23075.

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