DNA damage-induced degradation of Cdc25A does not lead to inhibition of Cdk2 activity in mouse embryonic stem cells
Language English Country Great Britain, England Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
20104581
DOI
10.1002/stem.311
Knihovny.cz E-resources
- MeSH
- Enzyme Activation genetics MeSH
- Cell Line MeSH
- Cell Cycle genetics MeSH
- Genes, cdc physiology MeSH
- Centrosome enzymology MeSH
- Checkpoint Kinase 1 MeSH
- Checkpoint Kinase 2 MeSH
- Cyclin-Dependent Kinase 2 genetics MeSH
- Cytoplasm enzymology MeSH
- DNA genetics radiation effects MeSH
- Embryonic Stem Cells cytology enzymology MeSH
- cdc25 Phosphatases genetics MeSH
- G1 Phase genetics MeSH
- Radiation, Ionizing MeSH
- Glycogen Synthase Kinase 3 metabolism MeSH
- Glycogen Synthase Kinase 3 beta MeSH
- Mice MeSH
- DNA Repair MeSH
- DNA Damage genetics MeSH
- Protein Serine-Threonine Kinases genetics MeSH
- Protein Kinases genetics MeSH
- Signal Transduction genetics MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Cdc25a protein, mouse MeSH Browser
- Cdk2 protein, mouse MeSH Browser
- Checkpoint Kinase 1 MeSH
- Checkpoint Kinase 2 MeSH
- Chek1 protein, mouse MeSH Browser
- Chek2 protein, mouse MeSH Browser
- Cyclin-Dependent Kinase 2 MeSH
- DNA MeSH
- cdc25 Phosphatases MeSH
- Gsk3b protein, mouse MeSH Browser
- Glycogen Synthase Kinase 3 MeSH
- Glycogen Synthase Kinase 3 beta MeSH
- Protein Serine-Threonine Kinases MeSH
- Protein Kinases MeSH
Cyclin-dependent kinase two (Cdk2) is the major regulator of the G1/S transition and the target of an activated G1 checkpoint in somatic cells. In the presence of DNA damage, Cdk2 kinase activity is abrogated by a deficiency of Cdc25A phosphatase, which is marked by Chk1/Chk2 for proteasomal degradation. Embryonic stem cells (ESCs) lack a G1 checkpoint response. In this study, we analyzed the G1 checkpoint pathways in mouse ESCs (mESCs) in the presence of DNA double-strand breaks evoked by ionizing radiation (IR). We show that checkpoint pathways, which operate during G1 phase in somatic cells, are activated in mESCs after IR; however, Cdk2 activity is not abolished. We demonstrate that Cdc25A is degraded in mESCs, but this degradation is not regulated by Chk1 and Chk2 kinases because they are sequestered to the centrosome. Instead, Cdc25A degradation is governed by glycogen synthase kinase-3beta kinase. We hypothesize that Cdc25A degradation does not inhibit Cdk2 activity because a considerable proportion of Cdk2 molecules localize to the cytoplasm and centrosomes in mESCs, where they may be sheltered from regulation by nuclear Cdc25A. Finally, we show that a high Cdk2 activity, which is irresponsive to DNA damage, is the driving force of the rapid escape of mESCs from G1 phase after DNA damage.
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