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Aging alters DNA structure-induced genetic instability in mice.

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Title: Aging alters DNA structure-induced genetic instability in mice.
Authors: Li, Tonia T.1, Wang, Guliang1, D'Amico, Alexandra M.1, Christensen, Laura A.1, Vasquez, Karen M.1 karen.vasquez@austin.utexas.edu
Source: Proceedings of the National Academy of Sciences of the United States of America. 4/14/2026, Vol. 123 Issue 15, p1-11. 18p.
Subjects: Aging, DNA structure, DNA repair, Mutagenesis, Genetic variation, Apoptosis, Laboratory mice
Abstract: Repetitive DNA sequences can adopt alternative (i.e., non-B) DNA structures, which represent an endogenous source of genetic instability. Z-DNA, a non-B-DNA structure, has been implicated in the development of age-related genetic disorders such as cancer and Alzheimer's disease. Previously, we found that Z-DNA is mutagenic in mammals; however, the impact of age on Z-DNA-induced genetic instability has not yet been explored. Here, we investigated the effects of aging on Z-DNA-induced genetic instability using a transgenic mutation reporter mouse model. We found that Z-DNA was more mutagenic than control B-DNA in all tissues tested. Contrary to initial expectations, Z-DNA-induced deletions decreased with age, whereas the point mutation frequencies remained unchanged. Our results suggest that while the cleavage activities on Z-DNA were similar in both age groups, the reduction of Z-DNA-induced deletion mutants in aged mice was due to attenuated DNA end-joining efficiency, which is required for the mutagenic processing of Z-DNA, and increased apoptosis. These results provide mechanistic insight into age-associated genetic instability and the aging-cancer link. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Repetitive DNA sequences can adopt alternative (i.e., non-B) DNA structures, which represent an endogenous source of genetic instability. Z-DNA, a non-B-DNA structure, has been implicated in the development of age-related genetic disorders such as cancer and Alzheimer's disease. Previously, we found that Z-DNA is mutagenic in mammals; however, the impact of age on Z-DNA-induced genetic instability has not yet been explored. Here, we investigated the effects of aging on Z-DNA-induced genetic instability using a transgenic mutation reporter mouse model. We found that Z-DNA was more mutagenic than control B-DNA in all tissues tested. Contrary to initial expectations, Z-DNA-induced deletions decreased with age, whereas the point mutation frequencies remained unchanged. Our results suggest that while the cleavage activities on Z-DNA were similar in both age groups, the reduction of Z-DNA-induced deletion mutants in aged mice was due to attenuated DNA end-joining efficiency, which is required for the mutagenic processing of Z-DNA, and increased apoptosis. These results provide mechanistic insight into age-associated genetic instability and the aging-cancer link. [ABSTRACT FROM AUTHOR]
ISSN:00278424
DOI:10.1073/pnas.2600482123