title: Intra-G1 arrest in response to UV irradiation in fission yeast.
abstract: G1 is a crucial phase of cell growth because the decision to begin another mitotic cycle is made during this period. Occurrence of DNA damage in G1 poses a particular challenge, because replication of damaged DNA can be deleterious and because no sister chromatid is present to provide a template for recombinational repair. We therefore have studied the response of Schizosaccharomyces pombe cells to UV irradiation in early G1 phase. We find that irradiation results in delayed progression through G1, as manifested most critically in the delayed formation of the pre-replication complex. This delay does not have the molecular hallmarks of known checkpoint responses: it is independent of the checkpoint proteins Rad3, Cds1, and Chk1 and does not elicit inhibitory phosphorylation of Cdc2. Irradiated cells eventually progress into S phase and arrest in early S by a rad3- and cds1-dependent mechanism, most likely the intra-S checkpoint. Caffeine alleviates both the intra-G1- and intra-S-phase delays. We suggest that intra-G1 delay may be widely conserved and discuss significance and possible mechanisms.
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Montebello, 0310 Oslo, Norway.
authors.forename: Esben A
authors.initials: EA
authors.lastname: Nilssen
authors.forename: Marianne
authors.initials: M
authors.lastname: Synnes
authors.forename: Nancy
authors.initials: N
authors.lastname: Kleckner
authors.forename: Beáta
authors.initials: B
authors.lastname: Grallert
authors.forename: Erik
authors.initials: E
authors.lastname: Boye
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D064447:Checkpoint Kinase 2; D002843:Chromatin / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005434:Flow Cytometry; D016193:G1 Phase; D005720:Gamma Rays; D064148:Minichromosome Maintenance Complex Component 4; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D016196:S Phase; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D029702:Schizosaccharomyces pombe Proteins; D014466:Ultraviolet Rays
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C578636:Cds1 protein, S pombe; D017346:Protein Serine-Threonine Kinases; D000251:Adenosine Triphosphatases; C061897:Rad3 protein, S cerevisiae; D004265:DNA Helicases; C092802:MCM4 protein, S cerevisiae; D064148:Minichromosome Maintenance Complex Component 4