Abstract
Whilst many studies have examined the role of the MAP Kinases in regulating the G1-->S transition, much less is known about the function of these pathways in regulating other cell cycle transitions. Stimulation of the conditional mutant Delta MEKK3:ER* in asynchronous hamster (CCl39) and rat (Rat-1) fibroblasts resulted in the strong activation of endogenous JNK and p38 but only a weak activation of ERK. Activation of Delta MEKK3:ER* inhibited cell proliferation through a combination of an initial G1 and G2 cell cycle arrest, followed by a delayed onset of apoptosis. When cells were synchronized in S phase with aphidicolin and then released, activation of Delta MEKK3:ER* resulted in the up-regulation of p21(CIP1) and a pronounced inhibition of cyclin A/CDK2 and cyclin B1/CDK1 kinase activity. Analysis of mitotic figures indicated that cells failed to enter mitosis, arresting late in G2. Delta MEKK3:ER*-mediated CDK inhibition and G2 arrest did not absolutely require p21(CIP1), since both events were observed in Rat-1 cells in which p21(CIP1) is transcriptionally silenced due to promoter methylation. Rather, CDK inhibition was associated with a down-regulation of cyclin A and B1 expression. Finally, application of the p38 inhibitor SB203580 partially restored cyclin B associated kinase activity and allowed cells to proceed through mitosis into the next G1 phase, suggesting that activation of the p38 alpha/beta 2 pathway can promote a G2 cell cycle arrest.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Aphidicolin / pharmacology
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Apoptosis / physiology
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CDC2 Protein Kinase / antagonists & inhibitors
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CDC2-CDC28 Kinases*
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Cells, Cultured / cytology
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Cricetinae
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Cyclin A / antagonists & inhibitors
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Cyclin B / antagonists & inhibitors
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Cyclin B1
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclin-Dependent Kinases / antagonists & inhibitors
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Cyclins / biosynthesis
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Cyclins / deficiency
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Cyclins / genetics
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DNA Methylation
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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Fibroblasts / cytology*
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G1 Phase / physiology
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G2 Phase / physiology*
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Gene Silencing
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Genes, Synthetic
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Humans
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Imidazoles / pharmacology
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JNK Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinase 3
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MAP Kinase Kinase Kinases / chemistry
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MAP Kinase Kinase Kinases / genetics
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MAP Kinase Kinase Kinases / physiology*
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Mitogen-Activated Protein Kinase 11
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism
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Mitogen-Activated Protein Kinases / physiology*
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Pyridines / pharmacology
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Rats
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Receptors, Estrogen / drug effects
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Receptors, Estrogen / genetics
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Recombinant Fusion Proteins / physiology
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Sequence Deletion
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Tamoxifen / analogs & derivatives*
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Tamoxifen / pharmacology
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p38 Mitogen-Activated Protein Kinases
Substances
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CCNB1 protein, human
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CDKN1A protein, human
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Ccnb1 protein, rat
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Cdkn1a protein, rat
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Cyclin A
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Cyclin B
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Cyclin B1
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclins
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Enzyme Inhibitors
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Imidazoles
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Pyridines
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Receptors, Estrogen
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Recombinant Fusion Proteins
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Tamoxifen
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afimoxifene
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Aphidicolin
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Protein Serine-Threonine Kinases
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CDC2 Protein Kinase
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CDC2-CDC28 Kinases
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CDK2 protein, human
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Cdk2 protein, rat
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinases
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase 11
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinase 3
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MAP Kinase Kinase Kinases
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MAP3K3 protein, human
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SB 203580