title: Consequences of abnormal CDK activity in S phase.
abstract: Cyclin Dependent Kinases (CDKs) are important regulators of DNA replication. In this work we have investigated the consequences of increasing or decreasing the CDK activity in S phase. To this end we identified S-phase regulators of the fission yeast CDK, Cdc2, and used appropriate mutants to modulate Cdc2 activity. In fission yeast Mik1 has been thought to be the main regulator of Cdc2 activity in S phase. However, we find that Wee1 has a major function in S phase and thus we used wee1 mutants to investigate the consequences of increased Cdc2 activity. These wee1 mutants display increased replication stress and, particularly in the absence of the S-phase checkpoint, accumulate DNA damage. Notably, more cells incorporate EdU in a wee1(-) strain as compared to wildtype, suggesting altered regulation of DNA replication. In addition, a higher number of cells contain chromatin-bound Cdc45, an indicator of active replication forks. In addition, we found that Cdc25 is required to activate Cdc2 in S phase and used a cdc25 mutant to explore a situation where Cdc2 activity is reduced. Interestingly, a cdc25 mutant has a higher tolerance for replication stress than wild-type cells, suggesting that reduced CDK activity in S phase confers resistance to at least some forms of replication stress.
authors.affiliation: a Department of Radiation Biology , Institute for Cancer Research, Oslo University Hospital , Oslo , Montebello , Norway.
authors.forename: Silje
authors.initials: S
authors.lastname: Anda
authors.affiliation: a Department of Radiation Biology , Institute for Cancer Research, Oslo University Hospital , Oslo , Montebello , Norway.
authors.forename: Christiane
authors.initials: C
authors.lastname: Rothe
authors.affiliation: a Department of Radiation Biology , Institute for Cancer Research, Oslo University Hospital , Oslo , Montebello , Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Boye
authors.affiliation: a Department of Radiation Biology , Institute for Cancer Research, Oslo University Hospital , Oslo , Montebello , Norway.
authors.forename: Beáta
authors.initials: B
authors.lastname: Grallert
mesh_terms: D016203:CDC2 Protein Kinase / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D064447:Checkpoint Kinase 2 / Q000235:genetics; D004249:DNA Damage; D004261:DNA Replication; D005804:Genes, Lethal; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000502:physiology*; D016196:S Phase; D012568:Schizosaccharomyces / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; C068689:wee1 protein, S pombe; D064447:Checkpoint Kinase 2; D011505:Protein-Tyrosine Kinases; C456840:rad3 protein, S pombe; D016203:CDC2 Protein Kinase; C469447:cdc2 protein, S pombe; C570820:Cdc25 protein, S pombe; D010749:Phosphoprotein Phosphatases
keywords: CDK; Cdc25; Cell cycle; Mik1; S phase; Wee1; fission yeast; replication stress