Delta MEKK3:ER* activation induces a p38 alpha/beta 2-dependent cell cycle arrest at the G2 checkpoint.
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.
Garner
Andrew P
AP
Inositide Laboratory, Signalling Programme, The Babraham Institute, Babraham Hall, Cambridge CB2 4AT, UK.
Weston
Claire R
CR
Todd
Daniel E
DE
Balmanno
Kathryn
K
Cook
Simon J
SJ
D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors; D042846:CDC2-CDC28 Kinases; D002478:Cells, Cultured / Q000166:cytology; D006224:Cricetinae; D019925:Cyclin A / Q000037:antagonists & inhibitors; D019926:Cyclin B / Q000037:antagonists & inhibitors; D056744:Cyclin B1; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D019175:DNA Methylation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology*; D016193:G1 Phase / Q000502:physiology; D016195:G2 Phase / Q000502:physiology*; D020868:Gene Silencing; D005813:Genes, Synthetic; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048748:MAP Kinase Kinase Kinase 3; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D048290:Mitogen-Activated Protein Kinase 11; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D017384:Sequence Deletion; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; C534701:Ccnb1 protein, rat; C493958:Cdkn1a protein, rat; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D013629:Tamoxifen; C016601:afimoxifene; D016590:Aphidicolin; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048290:Mitogen-Activated Protein Kinase 11; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048748:MAP Kinase Kinase Kinase 3; D020930:MAP Kinase Kinase Kinases; C482625:MAP3K3 protein, human; C093642:SB 203580