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Radiation-induced cell cycle arrest compromised by p21 deficiency
J Brugarolas1, C Chandrasekaran, J I Gordon
1Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge 02139, USA.
Nature
|October 12, 1995
Summary
The protein p21, a cell cycle inhibitor, does not affect intestinal cell differentiation or DNA damage-induced apoptosis. However, p21 deficiency impairs G1 cell cycle arrest in mouse fibroblasts after DNA damage.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The protein p21 acts as a dual inhibitor of cyclin-dependent kinases and proliferating-cell nuclear antigen (PCNA), crucial for cell cycle progression.
- The p21 gene is regulated by p53, suggesting a role in p53-dependent cell cycle arrest and apoptosis.
- p21 is also linked to cellular senescence and cell cycle withdrawal during terminal differentiation.
Purpose of the Study:
- To investigate the role of p21 in cell cycle regulation, differentiation, and apoptosis.
- To determine the in vivo function of p21 using genetically modified mouse models.
Main Methods:
- Utilized chimaeric mice composed of both p21 knockout (p21-/-) and wild-type (p21+/+) cells.
- Conducted immunohistochemical analyses on adult small intestine components.
- Assessed G1 arrest in p21-/- mouse embryo fibroblasts following DNA damage.
Main Results:
- Deletion of p21 had no discernible impact on the differentiation of intestinal epithelial cells.
- p21 deficiency did not affect p53-dependent apoptosis in response to irradiation.
- p21-/- mouse embryo fibroblasts exhibited impaired G1 arrest after DNA damage.
Conclusions:
- p21 is not essential for intestinal epithelial cell differentiation or irradiation-induced apoptosis.
- p21 plays a critical role in facilitating G1 cell cycle arrest in response to DNA damage.
- These findings clarify the specific functions of p21 in cell cycle control and tissue homeostasis.
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