Caloric Restriction Slows DNA Mutation Accumulation Across Multiple Tissues in Mice
A Cell study shows caloric restriction reduces genome-wide somatic mutation burden in liver, kidney, and neurons — reframing diet as a tool for genomic integrity.
Summary
Every cell in the body accumulates DNA mutations over time — a core hallmark of aging known as genomic instability. This study in Cell used ultra-high-fidelity duplex DNA sequencing to ask whether caloric restriction (CR) could slow this process. Researchers analyzed bulk liver, bulk kidney, individual liver cells (hepatocytes), and cerebellar neurons from mice on CR diets. CR significantly reduced the total burden of both point mutations and small insertions/deletions across all tissue types tested. It also dampened the activity of a poorly understood mutational process called SBS5, which drives most spontaneous mutations in mammals. Notably, the biggest mutation-reducing effect was seen in genomically silent, transcriptionally inactive regions of the genome. The findings position diet — specifically caloric reduction — as a lever for preserving genomic integrity throughout life, adding a new mechanistic dimension to why CR extends lifespan.
Detailed Summary
Somatic mutations — DNA changes that accumulate in non-reproductive cells throughout life — are a recognized hallmark of aging and a driver of cancer, cellular dysfunction, and organ decline. While caloric restriction (CR) is one of the most robust lifespan-extending interventions across species, its precise molecular mechanisms remain incompletely mapped. This study, published in Cell, investigates whether CR directly slows the rate at which somatic mutations accumulate in the genome.
Researchers employed high-fidelity duplex DNA sequencing — a technology capable of detecting rare mutations with very low error rates — to profile somatic mutation burdens genome-wide. They examined four sample types from CR and control mice: bulk liver tissue, bulk kidney tissue, isolated hepatocytes, and cerebellar neurons. This multi-tissue approach allowed comparison across dividing and post-mitotic cell populations.
CR consistently reduced both single-base substitution (point mutation) burdens and insertion/deletion (indel) burdens across all tissues, though the magnitude of reduction varied by tissue type. CR also significantly suppressed the activity of SBS5, an enigmatic mutational signature that accounts for the majority of spontaneous mutations in mammalian cells and whose origins remain poorly understood. Strikingly, the mutation-reducing effect of CR was most pronounced in transcriptionally inactive genomic regions, suggesting a mechanism linked to chromatin accessibility or DNA repair efficiency in silenced regions.
The implications are substantial. This work establishes genomic integrity as a modifiable dimension of aging — one that can be influenced by dietary intervention. It provides a plausible molecular explanation for CR's lifespan-extending effects and connects nutrition directly to genome maintenance biology.
Caveats include the animal model limitation; whether CR produces comparable somatic mutation reduction in humans remains unknown. The study is also based on restricted food intake, and practical translatability to intermittent fasting or caloric restriction mimetics (like rapamycin or metformin) is not yet established. Summary is based on abstract only.
Key Findings
- Caloric restriction reduced genome-wide somatic mutation burden across liver, kidney, hepatocytes, and cerebellar neurons in mice.
- CR suppressed both point mutations and insertions/deletions, with effect size varying by tissue type.
- CR significantly decreased activity of the SBS5 mutational signature, which drives most mammalian somatic mutations.
- Mutation reduction was greatest in transcriptionally inactive genomic regions, suggesting a novel repair or chromatin mechanism.
- The findings establish genomic integrity as a diet-modifiable axis of aging, not a fixed biological fate.
Methodology
Mice on caloric restriction were compared to ad libitum controls using high-fidelity duplex DNA sequencing, which minimizes sequencing errors to detect rare somatic mutations. Four sample types were analyzed: bulk liver, bulk kidney, purified hepatocytes, and cerebellar neurons. This design captures both dividing somatic cells and post-mitotic neurons.
Study Limitations
Results are from mice and may not directly translate to humans, where CR is difficult to sustain and effects on somatic mutation rates are unstudied at this resolution. The summary is based on the abstract only, limiting assessment of statistical methods, effect sizes, and controls. The mechanism behind CR's preferential mutation reduction in transcriptionally inactive regions is not yet explained.
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