title: Transcription-independent suppression of DNA synthesis by p53 in sperm-irradiated mouse zygotes.
abstract: Cell cycle arrest in response to DNA damage is important for the maintenance of genomic integrity in higher eukaryotes. We have previously reported the novel p53-dependent S-phase checkpoint operating in mouse zygotes fertilized with irradiated sperm. In the present study, we analysed the detail of the p53 function required for this S-phase checkpoint in mouse zygotes. The results indicate that ATM kinase is likely to be indispensable for the p53-dependent S-phase checkpoint since the suppression was abrogated by inhibitors such as caffeine and wortmannin. However, ATM phosphorylation site mutant proteins were still capable of suppressing DNA synthesis when microinjected into sperm-irradiated zygotes lacking the functional p53, suggesting that the target of the phosphorylation is not p53. In addition, the suppression was not affected by alpha-amanitin, and p53 protein mutated at the transcriptional activation domain was also functional in the suppression of DNA synthesis. However, p53 proteins mutated at the DNA-binding domain were devoid of the suppressing activity. Taken together, the transcription-independent function of p53 associated with the DNA-binding domain is involved in the S-phase checkpoint in collaboration with yet another unidentified target protein(s).
authors.affiliation: Department of Late Effect Studies, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Toyoshima
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Shimura
authors.forename: Satish-Kumar
authors.initials: SK
authors.lastname: Adiga
authors.forename: Masataka
authors.initials: M
authors.lastname: Taga
authors.forename: Kazunori
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Masao
authors.initials: M
authors.lastname: Inoue
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Yuan
authors.forename: Ohtsura
authors.initials: O
authors.lastname: Niwa
mesh_terms: D000483:Alleles; D000546:Amanitins / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D005260:Female; D016158:Genes, p53; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D016513:Mice, SCID; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016196:S Phase; D013094:Spermatozoa / Q000528:radiation effects*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000077191:Wortmannin; D014965:X-Rays; D015053:Zygote / Q000378:metabolism*
chemical_list: D000546:Amanitins; D000730:Androstadienes; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D002110:Caffeine; D004247:DNA; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D000077191:Wortmannin