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p53-dependent apoptosis suppresses radiation-induced teratogenesis
T Norimura1, S Nomoto, M Katsuki
1Department of Radiation Biology & Health, School of Medicine, University of Occupational & Environmental Health, Kitakyushu, Japan.
Nature Medicine
|May 1, 1996
Summary
The p53 gene acts as a guardian, preventing radiation-induced birth defects and fetal death. Mice lacking p53 (p53-/-) showed more anomalies but fewer deaths after radiation exposure compared to wild-type mice (p53+/+).
Area of Science:
- Developmental Biology
- Genetics
- Radiation Biology
Background:
- Approximately 50% of human conceptions are lost as spontaneous abortions, and 5% of births exhibit malformations.
- The mechanisms underlying spontaneous abortion and congenital malformations remain incompletely understood.
- The p53 tumor suppressor gene plays a critical role in cellular responses to DNA damage.
Purpose of the Study:
- To investigate the role of the p53 gene in preventing radiation-induced malformations and embryonic/fetal lethality.
- To compare the radiosensitivity of p53 null (p53-/-) and wild-type (p53+/+) mouse embryos.
Main Methods:
- X-irradiation of pregnant mice at different gestational days (day 3.5 and day 9.5).
- Comparison of malformation and lethality rates in p53-/- and p53+/+ offspring.
- Assessment of apoptotic DNA fragmentation in fetal tissues post-irradiation.
Main Results:
- p53-/- mice exhibited significantly higher incidences of radiation-induced anomalies (70%) and lower incidences of embryonic/fetal death (7%) compared to p53+/+ mice (20% anomalies, 60% death) after 2 Gy X-irradiation on day 9.5.
- Similar reciprocal effects on anomalies and lethality were observed following irradiation on day 3.5 of gestation.
- X-irradiation led to a marked increase in apoptotic DNA fragments in p53+/+ fetal tissues, but not in p53-/- fetal tissues.
Conclusions:
- Embryonic and fetal tissues possess a p53-dependent mechanism that acts as a 'guardian', eliminating cells with radiation-induced teratogenic DNA damage.
- This p53-mediated cell death pathway is crucial for preventing malformations and embryonic lethality following DNA damage during development.
- The findings highlight the critical role of p53 in safeguarding developmental integrity against genotoxic stress.
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