Related Experiment Videos
The response of Parp knockout mice against DNA damaging agents
M Masutani1, T Nozaki, K Nakamoto
1Biochemistry Division, National Cancer Center Research Institute, 1-1 Tsukiji 5-chome, Chuo-ku, Tokyo, 104-0045, Japan. mmasutan@gan2.ncc.go.jp
Abstract:
Gene-disruption studies involving poly(ADP-ribose) polymerase (Parp) have identified the various roles of Parp in cellular responses to DNA damage. The partial rescue of V[D]J recombination process in SCID/Parp(-/-) double mutant mice indicates the participation of Parp in the repair of DNA strand break. Parp(-/-) mice are more sensitive to the lethal effects of alkylating agents. Parp is also thought to be involved in base-excision repair after DNA damage caused by alkylating agents. On the other hand, resistance of Parp(-/-) mice to DNA damage induced by reactive oxygen species implicates the contribution of Parp to cell death through NAD depletion. Parp(-/-) mice with two different genetic backgrounds also show enhanced sensitivity to the lethal effects of gamma-irradiation. Parp(-/-) mice show more severe villous atrophy of the small intestine compared to the wild-type counterpart in a genetic background of 129Sv/C57BL6. Other forms of enhanced tissue damage have been identified in Parp(-/-) mice with a genetic background of 129Sv/ICR. For example, Parp(-/-) mice exhibit extensive hemorrhage in the glandular stomach and other tissues, such as the testes, after gamma-irradiation. Severe myelosuppression is also observed in both Parp(+/+) and Parp(-/-) mice, but Parp(+/+) mice show extensive extramedullary hematopoiesis in the spleen during the recovery phase of post-irradiation, whereas the spleen of Parp(-/-) mice exhibits severe atrophy with no extramedullary hematopoiesis. The absence of extramedullary hematopoiesis in the spleen is probably the underlying mechanism of hemorrhagic tendency in various tissues of Parp(-/-) mice. These findings suggest that loss of Parp activity could contribute to post-irradiation tissue hemorrhage.
Insights
Poly(ADP-ribose) polymerase (Parp) plays a role in DNA repair and cell death. Parp deficiency in mice leads to increased sensitivity to DNA damaging agents and post-irradiation hemorrhage.
Area of Science:
- Molecular Biology
- Genetics
- Cellular Biology
Background:
- Poly(ADP-ribose) polymerase (Parp) is crucial for cellular responses to DNA damage.
- Gene-disruption studies reveal Parp's involvement in DNA repair pathways.
- Parp's role in V[D]J recombination and base-excision repair is suggested.
Purpose of the Study:
- To investigate the multifaceted roles of Parp in DNA damage response.
- To elucidate the consequences of Parp deficiency on organismal sensitivity to genotoxic agents.
- To understand Parp's contribution to cell death and tissue homeostasis.
Main Methods:
- Gene-disruption studies in Parp(-/-) mice.
- Assessment of V[D]J recombination efficiency.
- Evaluation of sensitivity to alkylating agents and gamma-irradiation.
- Histopathological analysis of various tissues (small intestine, stomach, testes, spleen).
Main Results:
- Parp(-/-) mice show partial rescue of V[D]J recombination, indicating a role in DNA strand break repair.
- Parp(-/-) mice exhibit increased sensitivity to alkylating agents and gamma-irradiation.
- Resistance to reactive oxygen species-induced damage suggests Parp's role in NAD depletion-mediated cell death.
- Parp(-/-) mice display enhanced tissue damage, including villous atrophy, gastric hemorrhage, and severe splenic atrophy with impaired extramedullary hematopoiesis post-irradiation.
Conclusions:
- Loss of Parp activity impairs DNA repair and increases sensitivity to DNA damaging agents.
- Parp deficiency contributes to cell death via NAD depletion and exacerbates tissue damage, particularly hemorrhage, after irradiation due to impaired hematopoiesis.