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Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos
Published on: June 6, 2016
p21 provides stage specific DNA damage control to preimplantation embryos
S K Adiga1, M Toyoshima, K Shiraishi
1Kasturba Medical College, Manipal, India.
Oncogene
|April 11, 2007
Summary
Early embryo development shows stage-specific DNA damage responses. p21 activation causes cell cycle arrest and apoptosis, impacting chromosome stability and embryonic development.
Area of Science:
- Developmental Biology
- Genetics
- Cell Biology
Background:
- Early eukaryotic embryogenesis exhibits limited DNA damage response pathways.
- Key checkpoints like G1/S, G2/M, and apoptosis are often absent.
- Understanding these responses is crucial for early development.
Purpose of the Study:
- To investigate DNA damage response in preimplantation embryos after sperm irradiation.
- To identify stage-specific damage response mechanisms during early development.
- To elucidate the role of p21 in response to DNA damage.
Main Methods:
- Fertilization of oocytes with 6 Gy irradiated sperm.
- Monitoring of embryo development and morphological changes.
- Analysis of p21 activation, micronuclei formation, and apoptosis.
- Comparison between p21 knockout and wild-type embryos.
Main Results:
- Sperm-irradiated embryos showed normal development for 2.5 days, followed by a delay at day 3.5.
- Delayed embryos exhibited p21 activation and increased micronuclei, indicating chromosome instability.
- Apoptosis was primarily observed in the inner cell mass of day 4.0 embryos.
- p21 knockout embryos lacked developmental delay but showed enhanced chromosome instability and apoptosis.
Conclusions:
- DNA damage responses are stage-specific during preimplantation development.
- p53-dependent S checkpoint operates at the zygote stage.
- p21 mediates cell cycle arrest at morula/blastocyst stages.
- Apoptosis occurs post-blastocyst stage in the inner cell mass.
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