title: p53-dependent S-phase damage checkpoint and pronuclear cross talk in mouse zygotes with X-irradiated sperm.
abstract: One difficulty in analyzing the damage response is that the effect of damage itself and that of cellular response are hard to distinguish in irradiated cells. In mouse zygotes, damage can be introduced by irradiated sperm, while damage response can be studied in the unirradiated maternal pronucleus. We have analyzed the p53-dependent damage responses in irradiated-sperm mouse zygotes and found that a p53-responsive reporter was efficiently activated in the female pronucleus. [(3)H]thymidine labeling experiments indicated that irradiated-sperm zygotes were devoid of G(1)/S arrest, but pronuclear DNA synthesis was suppressed equally in male and female pronuclei. p53(-/-) zygotes lacked this suppression, which was corrected by microinjection of glutathione S-transferase-p53 fusion protein. In contrast, p21(-/-) zygotes exhibited the same level of suppression upon fertilization by irradiated sperm. About a half of the 6-Gy-irradiated-sperm zygotes managed to synthesize a full DNA content by prolonging S phase, while the other half failed to do so. Regardless of the DNA content, all the zygotes cleaved to become two-cell-stage embryos. These results revealed the presence of p53-dependent pronuclear cross talk and a novel function of p53 in the S-phase DNA damage checkpoint of mouse zygotes.
authors.affiliation: Department of Late Effect Studies, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Shimura
authors.forename: Masao
authors.initials: M
authors.lastname: Inoue
authors.forename: Masataka
authors.initials: M
authors.lastname: Taga
authors.forename: Kazunori
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Norio
authors.initials: N
authors.lastname: Uematsu
authors.forename: Norihide
authors.initials: N
authors.lastname: Takei
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Yuan
authors.forename: Takashi
authors.initials: T
authors.lastname: Shinohara
authors.forename: Ohtsura
authors.initials: O
authors.lastname: Niwa
mesh_terms: D000818:Animals; D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D004249:DNA Damage / Q000235:genetics / Q000528:radiation effects*; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005307:Fertilization in Vitro; D017930:Genes, Reporter / Q000235:genetics; D008297:Male; D051379:Mice; D008938:Mitosis / Q000528:radiation effects; D016196:S Phase; D013094:Spermatozoa / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015053:Zygote / Q000166:cytology* / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D004247:DNA