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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.
Amon,
Regulation of p34CDC28 tyrosine phosphorylation is not required for entry into mitosis in S. cerevisiae.
1992, Pubmed,
Xenbase
Amon,
Regulation of p34CDC28 tyrosine phosphorylation is not required for entry into mitosis in S. cerevisiae.
1992,
Pubmed
,
Xenbase
Dasso,
Completion of DNA replication is monitored by a feedback system that controls the initiation of mitosis in vitro: studies in Xenopus.
1990,
Pubmed
,
Xenbase
Davis,
Monoclonal antibodies to mitotic cells.
1983,
Pubmed
,
Xenbase
Dunphy,
The cdc25 protein contains an intrinsic phosphatase activity.
1991,
Pubmed
Edgar,
Transcriptional regulation of string (cdc25): a link between developmental programming and the cell cycle.
1994,
Pubmed
Elledge,
Cell cycle checkpoints: preventing an identity crisis.
1996,
Pubmed
Enoch,
Coupling M phase and S phase: controls maintaining the dependence of mitosis on chromosome replication.
1991,
Pubmed
Fenton,
A conserved mitotic kinase active at late anaphase-telophase in syncytial Drosophila embryos.
1993,
Pubmed
Ferrell,
Cell cycle tyrosine phosphorylation of p34cdc2 and a microtubule-associated protein kinase homolog in Xenopus oocytes and eggs.
1991,
Pubmed
,
Xenbase
Furnari,
Cdc25 mitotic inducer targeted by chk1 DNA damage checkpoint kinase.
1997,
Pubmed
Gard,
Centrosome duplication continues in cycloheximide-treated Xenopus blastulae in the absence of a detectable cell cycle.
1990,
Pubmed
,
Xenbase
Gautier,
Dephosphorylation and activation of Xenopus p34cdc2 protein kinase during the cell cycle.
1989,
Pubmed
,
Xenbase
Gautier,
cdc25 is a specific tyrosine phosphatase that directly activates p34cdc2.
1991,
Pubmed
,
Xenbase
Glover,
Polo kinase: the choreographer of the mitotic stage?
1996,
Pubmed
Golsteyn,
Cell cycle regulation of the activity and subcellular localization of Plk1, a human protein kinase implicated in mitotic spindle function.
1995,
Pubmed
Gould,
Tyrosine phosphorylation of the fission yeast cdc2+ protein kinase regulates entry into mitosis.
1989,
Pubmed
Hamanaka,
Polo-like kinase is a cell cycle-regulated kinase activated during mitosis.
1995,
Pubmed
Hartley,
In vivo regulation of the early embryonic cell cycle in Xenopus.
1996,
Pubmed
,
Xenbase
Hartwell,
Checkpoints: controls that ensure the order of cell cycle events.
1989,
Pubmed
Hoffmann,
Phosphorylation and activation of human cdc25-C by cdc2--cyclin B and its involvement in the self-amplification of MPF at mitosis.
1993,
Pubmed
,
Xenbase
Holloway,
Anaphase is initiated by proteolysis rather than by the inactivation of maturation-promoting factor.
1993,
Pubmed
,
Xenbase
Izumi,
Elimination of cdc2 phosphorylation sites in the cdc25 phosphatase blocks initiation of M-phase.
1993,
Pubmed
,
Xenbase
Izumi,
Periodic changes in phosphorylation of the Xenopus cdc25 phosphatase regulate its activity.
1992,
Pubmed
,
Xenbase
Izumi,
Phosphorylation and activation of the Xenopus Cdc25 phosphatase in the absence of Cdc2 and Cdk2 kinase activity.
1995,
Pubmed
,
Xenbase
Kornbluth,
Membrane localization of the kinase which phosphorylates p34cdc2 on threonine 14.
1994,
Pubmed
,
Xenbase
Kuang,
cdc25 is one of the MPM-2 antigens involved in the activation of maturation-promoting factor.
1994,
Pubmed
,
Xenbase
Kuang,
At least two kinases phosphorylate the MPM-2 epitope during Xenopus oocyte maturation.
1993,
Pubmed
,
Xenbase
Kumagai,
Purification and molecular cloning of Plx1, a Cdc25-regulatory kinase from Xenopus egg extracts.
1996,
Pubmed
,
Xenbase
Kumagai,
The cdc25 protein controls tyrosine dephosphorylation of the cdc2 protein in a cell-free system.
1991,
Pubmed
,
Xenbase
Kumagai,
Regulation of the cdc25 protein during the cell cycle in Xenopus extracts.
1992,
Pubmed
,
Xenbase
Lane,
Cell-cycle control: POLO-like kinases join the outer circle.
1997,
Pubmed
,
Xenbase
Lane,
Antibody microinjection reveals an essential role for human polo-like kinase 1 (Plk1) in the functional maturation of mitotic centrosomes.
1996,
Pubmed
Langan,
Mammalian growth-associated H1 histone kinase: a homolog of cdc2+/CDC28 protein kinases controlling mitotic entry in yeast and frog cells.
1989,
Pubmed
,
Xenbase
Lee,
Plk is a functional homolog of Saccharomyces cerevisiae Cdc5, and elevated Plk activity induces multiple septation structures.
1997,
Pubmed
,
Xenbase
Lee,
cdc25+ encodes a protein phosphatase that dephosphorylates p34cdc2.
1992,
Pubmed
,
Xenbase
Lee,
Plk is an M-phase-specific protein kinase and interacts with a kinesin-like protein, CHO1/MKLP-1.
1995,
Pubmed
Lew,
A cell cycle checkpoint monitors cell morphogenesis in budding yeast.
1995,
Pubmed
Llamazares,
polo encodes a protein kinase homolog required for mitosis in Drosophila.
1991,
Pubmed
Matten,
Positive feedback between MAP kinase and Mos during Xenopus oocyte maturation.
1996,
Pubmed
,
Xenbase
Moreno,
Regulation of mitosis by cyclic accumulation of p80cdc25 mitotic inducer in fission yeast.
1990,
Pubmed
Mueller,
Myt1: a membrane-associated inhibitory kinase that phosphorylates Cdc2 on both threonine-14 and tyrosine-15.
1995,
Pubmed
,
Xenbase
Murray,
The role of cyclin synthesis and degradation in the control of maturation promoting factor activity.
1989,
Pubmed
,
Xenbase
Ohkura,
The conserved Schizosaccharomyces pombe kinase plo1, required to form a bipolar spindle, the actin ring, and septum, can drive septum formation in G1 and G2 cells.
1995,
Pubmed
Parker,
p107wee1 is a dual-specificity kinase that phosphorylates p34cdc2 on tyrosine 15.
1992,
Pubmed
Parker,
Phosphorylation and inactivation of the mitotic inhibitor Wee1 by the nim1/cdr1 kinase.
1993,
Pubmed
Peng,
Mitotic and G2 checkpoint control: regulation of 14-3-3 protein binding by phosphorylation of Cdc25C on serine-216.
1997,
Pubmed
Roy,
Mos proto-oncogene function during oocyte maturation in Xenopus.
1996,
Pubmed
,
Xenbase
Sagata,
The c-mos proto-oncogene product is a cytostatic factor responsible for meiotic arrest in vertebrate eggs.
1989,
Pubmed
,
Xenbase
Sagata,
Function of c-mos proto-oncogene product in meiotic maturation in Xenopus oocytes.
1988,
Pubmed
,
Xenbase
Sanchez,
Conservation of the Chk1 checkpoint pathway in mammals: linkage of DNA damage to Cdk regulation through Cdc25.
1997,
Pubmed
Smythe,
Coupling of mitosis to the completion of S phase in Xenopus occurs via modulation of the tyrosine kinase that phosphorylates p34cdc2.
1992,
Pubmed
,
Xenbase
Taagepera,
The MPM-2 antibody inhibits mitogen-activated protein kinase activity by binding to an epitope containing phosphothreonine-183.
1994,
Pubmed
,
Xenbase
Tang,
Two distinct mechanisms for negative regulation of the Wee1 protein kinase.
1993,
Pubmed
,
Xenbase
Tavares,
The conserved mitotic kinase polo is regulated by phosphorylation and has preferred microtubule-associated substrates in Drosophila embryo extracts.
1996,
Pubmed
Vandré,
Distribution of cytoskeletal proteins sharing a conserved phosphorylated epitope.
1986,
Pubmed
Westendorf,
Cloning of cDNAs for M-phase phosphoproteins recognized by the MPM2 monoclonal antibody and determination of the phosphorylated epitope.
1994,
Pubmed
