The MPM-2 antibody inhibits mitogen-activated protein kinase activity by binding to an epitope containing phosphothreonine-183.

Taagepera, Salme; Dent, Paul; Her, Jeng-Horng; Sturgill, Thomas W.; Gorbsky, Gary J.

doi:10.1091/mbc.5.11.1243

Cited by 22 publications

(28 citation statements)

References 43 publications

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“…Plks are members of a small subset of protein kinases that generate phosphoepitopes recognized by the MPM-2 antibody (3,27,53). This antibody recognizes a proline-directed epitope and reacts with a large number of proteins phosphorylated specifically at mitosis, which are located on several important mitotic structures, including centrosomes and kinetochores (56,57).…”

Section: Discussionmentioning

confidence: 99%

Activated Polo-Like Kinase Plx1 Is Required at Multiple Points during Mitosis in Xenopus laevis

Qian

Erikson

et al. 1998

Molecular and Cellular Biology

221

256

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Entry into mitosis depends upon activation of the dual-specificity phosphatase Cdc25C, which dephosphorylates and activates the cyclin B-Cdc2 complex. Previous work has shown that the Xenopus polo-like kinase Plx1 can phosphorylate and activate Cdc25C in vitro. In the work presented here, we demonstrate that Plx1 is activated in vivo during oocyte maturation with the same kinetics as Cdc25C. Microinjection of wild-type Plx1 into Xenopus oocytes accelerated the rate of activation of Cdc25C and cyclin B-Cdc2. Conversely, microinjection of either an antibody against Plx1 or kinase-dead Plx1 significantly inhibited the activation of Cdc25C and cyclin B-Cdc2. This effect could be reversed by injection of active Cdc25C, indicating that Plx1 is upstream of Cdc25C. However, injection of Cdc25C, which directly activates cyclin B-Cdc2, also caused activation of Plx1, suggesting that a positive feedback loop exists in the Plx1 activation pathway. Other experiments show that injection of Plx1 antibody into early embryos, which do not require Cdc25C for the activation of cyclin B-Cdc2, resulted in an arrest of cleavage that was associated with monopolar spindles. These results demonstrate that in Xenopus laevis, Plx1 plays important roles both in the activation of Cdc25C at the initiation of mitosis and in spindle assembly at late stages of mitosis.Progression through the eucaryotic cell cycle is controlled by the activation of several cyclin-dependent kinases (cdks) at specific points in the cycle. To maintain genomic stability, surveillance mechanisms known as checkpoints monitor the completion of essential events to prevent cell cycle progression if DNA is damaged, unreplicated, or improperly assembled on the mitotic spindle (reviewed in references 6 and 20). The biochemistry of cell cycle-dependent checkpoints is best characterized during G 2 phase, when checkpoints determine whether a cell enters mitosis. The cdk that drives the G 2 /M transition, cyclin B-Cdc2, is not activated on schedule if DNA is damaged or if DNA replication is incomplete (2; reviewed in reference 7). Both the DNA damage and DNA replication checkpoints regulate cyclin B-Cdc2 activation in part through the phosphatase Cdc25C. Throughout late S and early G 2 phases, cyclin B is synthesized and immediately complexes with Cdc2, which is kept catalytically inactive by phosphorylation of Tyr15 and Thr14 in the ATP-binding site (12,16,29). This phosphorylation and inactivation is catalyzed by the protein kinases Wee1 and Myt1 (42,45), and dephosphorylation and activation of cyclin B-Cdc2 is catalyzed by the phosphatase Cdc25C (4, 13, 37).Studies on vertebrate Cdc25C have shown that its ability to dephosphorylate cyclin B-Cdc2 and initiate mitosis is regulated by two distinct mechanisms. Activation of Cdc25C requires phosphorylation on specific serine and threonine sites (21,25,31), and this phosphorylation fails to occur if DNA synthesis is incomplete and the replication checkpoint is activated.

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Section: Discussionmentioning

confidence: 99%

Activated Polo-Like Kinase Plx1 Is Required at Multiple Points during Mitosis in Xenopus laevis

Qian

Erikson

et al. 1998

Molecular and Cellular Biology

221

256

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“…Previous studies have identified six different MPM-2 kinases including cdc2 kinase, NIMA, Polo-like kinase, a poorly identified mitotic kinase called ME kinase-H, MAP kinase, and the two isoforms of MAP kinase kinase (22,27,28,32,33,54). We now report that CK2 also has MPM-2 kinase activity and that this activity results in the generation of a specific MPM-2 epitope on topoisomerase II␣, an important mitotic protein required for chromosome condensation as well as for segregation of intertwined sister chromatids (for review, see Ref.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to topoisomerase II␣, more than 50 other phosphorylated proteins are recognized by the MPM-2 antibody including microtubule-associated proteins, components of the anaphase-promoting complex, phosphatases, and a number of protein kinases including protein kinase CK2 (16, 18 -26). Multiple kinases are able to generate MPM-2 epitopes including mitotic kinases such as cdc2 kinase as well as kinases which are also active during interphase such as MAP 1 kinase (22,(27)(28)(29)(30)(31)(32). Interestingly, some MPM-2 kinases as, for example, NIMA are themselves activated by other MPM-2 kinases indicating the complexity of the signaling pathways which regulate mitotic entry (22,33).…”

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confidence: 99%

Mitotic Phosphorylation of DNA Topoisomerase II α by Protein Kinase CK2 Creates the MPM-2 Phosphoepitope on Ser-1469

Escargueil

Plisov

Filhol

et al. 2000

Journal of Biological Chemistry

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DNA topoisomerase II␣ is required for chromatin condensation during prophase. This process is temporally linked with the appearance of mitosis-specific phosphorylation sites on topoisomerase II␣ including one recognized by the MPM-2 monoclonal antibody. We now report that the ability of mitotic extracts to create the MPM-2 epitope on human topoisomerase II␣ is abolished by immunodepletion of protein kinase CK2. Furthermore, the MPM-2 phosphoepitope on topoisomerase II␣ can be generated by purified CK2. Phosphorylation of C-truncated topoisomerase II␣ mutant proteins conclusively shows, that the MPM-2 epitope is present in the last 163 amino acids. Use of peptides containing all conserved CK2 consensus sites in this region indicates that only the peptide containing Arg-1466 to Ala-1485 is able to compete with topoisomerase II␣ for binding of the MPM-2 antibody. Replacement of Ser-1469 with Ala abolishes the ability of the phosphorylated peptide to bind to the MPM-2 antibody while a peptide containing phosphorylated Ser-1469 binds tightly. Surprisingly, the MPM-2 phosphoepitope influences neither the catalytic activity of topoisomerase II␣ nor its ability to form molecular complexes with CK2 in vitro. In conclusion, we have identified protein kinase CK2 as a new MPM-2 kinase able to phosphorylate an important mitotic protein, topoisomerase II␣, on Ser-1469.

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“…This antibody reacts with epitopes that are specifically phosphorylated during mitosis. Several proteins detected by this antibody have already been identified, but so far p42 mapk is the only protein for which the functional significance of the MPM-2 epitope has been established (53). Several protein kinases have been implicated in the phosphorylation of MPM-2 epitopes, including mitogen-activated protein kinase kinase, mitogen-activated protein kinase, and cdc2 (53)(54)(55)(56).…”

Section: Fig 6 ␤-Catenin Plakoglobin and P120mentioning

confidence: 99%

Modification of the E-cadherin-Catenin Complex in Mitotic Madin-Darby Canine Kidney Epithelial Cells

Bauer

Lickert

Kemler

et al. 1998

Journal of Biological Chemistry

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One of the hallmarks of polarized epithelial cells undergoing mitosis is their rounded morphology. This phenotype correlates with a reduced cell-substratum adhesion, apparently caused by a modulation of integrin function. However, it is still unclear whether the cadherin-mediated cell-cell adhesion is affected as well. To address this question, the cadherin complex was analyzed in different cell cycle stages of Madin-Darby canine kidney cells. By immunofluorescence, mitotic Madin-Darby canine kidney cells showed an increased staining of E-cadherin and the catenins (␣-catenin, ␤-catenin, plakoglobin, p120 ctn ) in the cytosol, suggesting a reorganization of the cadherin-catenin complex during mitosis. Biochemical analysis revealed that the overall amount of these components, as well as the proportion of the complex associated with the actin cytoskeleton, remained unchanged in mitotic cells. However, we found evidence for an internalization of E-cadherin during mitosis. In addition, the cadherincatenin complex was analyzed for mitosis-specific changes in phosphorylation. We report a decrease in the tyrosine phosphorylation of ␤-catenin, plakoglobin, and p120 ctn during mitosis. Moreover, we observed a mitosisspecific Ser/Thr-phosphorylation of p120 ctn , as detected by the MPM-2 antibody. Hence, the cadherin/catenin complex is a target for different posttranslational modifications during mitosis, which may also have a profound impact on cadherin-mediated cell-cell adhesion.

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The MPM-2 antibody inhibits mitogen-activated protein kinase activity by binding to an epitope containing phosphothreonine-183.

Cited by 22 publications

References 43 publications

Activated Polo-Like Kinase Plx1 Is Required at Multiple Points during Mitosis in Xenopus laevis

Activated Polo-Like Kinase Plx1 Is Required at Multiple Points during Mitosis in Xenopus laevis

Mitotic Phosphorylation of DNA Topoisomerase II α by Protein Kinase CK2 Creates the MPM-2 Phosphoepitope on Ser-1469

Modification of the E-cadherin-Catenin Complex in Mitotic Madin-Darby Canine Kidney Epithelial Cells

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