The stress-activated protein kinases p38alpha/beta and JNK1/2 cooperate with Chk1 to inhibit mitotic entry upon DNA replication arrest
Program in Molecular Medicine
Medical Subject Headings
Animals; Aphidicolin; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; Cyclin B1; DNA; *DNA Replication; DNA-Binding Proteins; Embryo, Mammalian; Enzyme Activation; Fibroblasts; Hydroxyurea; JNK Mitogen-Activated Protein Kinases; Kinetics; MAP Kinase Kinase 3; MAP Kinase Kinase 6; Mice; Mitogen-Activated Protein Kinase 11; Mitogen-Activated Protein Kinase 14; *Mitosis; NIH 3T3 Cells; Protein Kinases; Protein-Serine-Threonine Kinases; S Phase; Tumor Suppressor Proteins
Biochemistry | Cell Biology | Cellular and Molecular Physiology | Molecular Biology
Accurate DNA replication is crucial for the maintenance of genome integrity. To this aim, cells have evolved complex surveillance mechanisms to prevent mitotic entry in the presence of partially replicated DNA. ATR and Chk1 are key elements in the signal transduction pathways of DNA replication checkpoint; however, other kinases also make significant contributions. We show here that the stress kinases p38 and JNK are activated when DNA replication is blocked, and that their activity allows S/M, but not G 2/M, checkpoint maintenance when Chk1 is inhibited. Activation of both kinases by DNA replication inhibition is not mediated by the caffeine-sensitive kinases ATR or ATM. Phosphorylation of MKK3/6 and MKK4, p38 and JNK upstream kinases was also observed upon DNA replication inhibition. Using a genetic approach, we dissected the p38 pathway and showed that both p38alpha and p38beta isoforms collaborate to inhibit mitotic entry. We further defined MKK3/6 and MK2/3 as the key upstream and downstream elements in the p38 signaling cascade after replication arrest. Accordingly, we found that the stress signaling pathways collaborate with Chk1 to keep cyclin B1/Cdk1 complexes inactive when DNA replication is inhibited, thereby preventing cell cycle progression when DNA replication is stalled. Our results show a complex response to replication stress, where multiple pathways are activated and fulfill overlapping roles to prevent mitotic entry with unreplicated DNA.
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Citation: Cell Cycle. 2012 Oct 1;11(19):3627-37. doi: 10.4161/cc.21917. Epub 2012 Aug 30. Link to article on publisher's site
Llopis, Alba; Salvador, Noelia; Ercilla, Amaia; Guaita-Esteruelas, Sandra; Barrantes, Ivan del Barco; Gupta, Jalaj; Gaestel, Matthias; Davis, Roger J.; Nebreda, Angel R.; and Agell, Neus, "The stress-activated protein kinases p38alpha/beta and JNK1/2 cooperate with Chk1 to inhibit mitotic entry upon DNA replication arrest" (2012). Davis Lab Publications. 2.