Researchers led by Alina Michler and Sarah Kieling, with corresponding author Thomas Haaf from Julius Maximilians University, Germany, investigated changes in ribosomal DNA (rDNA) copy number and methylation in a cohort of 280 individuals from birth to 18 years of age. Analysing blood samples using droplet digital PCR and deep bisulfite sequencing, the study published in Aging (Volume 17, Issue 6, June 16, 2025) demonstrated that age-related epigenetic changes – specifically, a loss of active rDNA copies and increased methylation – were absent during childhood and adolescence. Instead, active, unmethylated rDNA copies slightly increased, supporting the hypothesis that biological aging commences after reproductive maturity, and that rDNA methylation patterns are actively maintained in somatic tissues of young individuals.
Epigenetic Markers and the Onset of Aging
Researchers investigating the onset of aging discovered that epigenetic changes typically associated with the process in adults were not present before sexual maturity. The study, published in Aging (Aging-US), Volume 17, Issue 6, analysed blood samples from 280 individuals, ranging from newborns to 18 years of age, to examine changes in ribosomal DNA (rDNA) copy number and methylation. Researchers measured methylation – a chemical modification of DNA that switches genes on or off – alongside rDNA copy numbers.
The results demonstrated that the gradual loss of active rDNA copies and increased methylation – hallmarks of aging observed in adults – were absent in children and teenagers. In fact, the number of active, unmethylated rDNA copies slightly increased during childhood and adolescence, suggesting an active maintenance of rDNA in a youthful state. These findings support the hypothesis that biological aging begins only after the body reaches reproductive maturity.
The study also indicated that changes in rDNA copy numbers were not associated with unexplained developmental delays, implying that these epigenetic processes are unlikely to be involved in early-life syndromes. Collectively, the data suggest that the rDNA hypomethylation state is actively maintained in somatic tissues of young individuals, providing insights into the molecular clock of aging. This research expands the understanding of aging processes and suggests potential avenues for delaying them by exploring how youthful ribosomal DNA methylation patterns are maintained.
Ribosomal DNA Dynamics Throughout Development
The research examined blood samples from 280 individuals, ranging from newborns to 18 years of age, including both healthy individuals and those with developmental delays, to measure changes in rDNA copy number and assess methylation patterns. Researchers specifically measured how genes are switched on or off through methylation, a chemical modification of DNA, alongside the quantification of rDNA copies.
Findings revealed that during childhood and adolescence, the number of active, unmethylated rDNA copies slightly increased, indicating an active maintenance of rDNA in a youthful state. This supports the contention that biological aging commences only after the body reaches reproductive maturity, as the gradual loss of active rDNA copies and increased ribosomal DNA methylation – hallmarks of aging observed in adults – were absent in the studied age group.
Furthermore, the study indicates that changes in rDNA copy numbers are not associated with unexplained developmental delays, suggesting these epigenetic processes are likely not involved in early-life syndromes. The data collectively suggest that the rDNA hypomethylation state is actively maintained in somatic tissues of young individuals, contributing to an expanded understanding of the molecular clock of aging.
Implications for Cellular Resilience and Future Research
The study provides a foundation for future research aimed at extending cellular health beyond adolescence. This research expands the understanding of the molecular clock of aging and suggests potential new avenues for delaying aging processes by exploring how youthful ribosomal DNA methylation patterns are maintained.
Collectively, the data suggest that the rDNA hypomethylation state is actively maintained in somatic tissues of young individuals, providing insights into the molecular clock of aging. These insights expand the understanding of the molecular clock of aging and suggest potential new avenues for delaying aging processes by exploring how youthful ribosomal DNA methylation patterns are maintained.
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