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Telomere dysfunction impairs DNA repair and enhances sensitivity to ionizing radiation
K K Wong1, S Chang, S R Weiler
1Department of Adult Oncology, Dana Farber Cancer Institute, Boston, Massachusetts, USA.
Nature Genetics
|September 6, 2000
Summary
Telomere dysfunction, not telomerase deficiency alone, causes radiosensitivity. Impaired telomeres lead to accelerated mortality and cellular damage following ionizing radiation exposure in mice.
Area of Science:
- Molecular Biology
- Genetics
- Radiation Biology
Background:
- Telomeres are crucial nucleoprotein complexes protecting eukaryotic chromosomes.
- Telomere dysfunction leads to genetic instability and loss of cellular viability.
- Telomeres play a role in DNA repair, including non-homologous end-joining (NHEJ).
Purpose of the Study:
- To investigate the role of telomerase and telomere function in response to ionizing radiation.
- To assess the impact of telomere dysfunction on cellular and organismal radiosensitivity using telomerase-deficient mice.
Main Methods:
- Utilized telomerase-deficient mice (Terc-/-) across generations.
- Assessed cellular responses including apoptosis, clonogenic survival, and DNA repair kinetics.
- Analyzed chromosomal integrity and cytogenetic profiles post-ionizing radiation exposure.
Main Results:
- Telomere dysfunction in late-generation Terc-/- mice induced a radiosensitivity syndrome with accelerated mortality.
- Telomere-dysfunctional cells exhibited increased apoptosis (gastrointestinal crypt stem cells, thymocytes) and reduced survival (MEFs).
- Radiosensitivity correlated with delayed DNA break repair, persistent breaks, and complex chromosomal aberrations.
Conclusions:
- Functionally intact telomeres are essential for appropriate genomic, cellular, and organismal responses to ionizing radiation.
- Telomere dysfunction significantly exacerbates the damaging effects of ionizing radiation, leading to premature aging and mortality.