Bernardo Lemos, Ph.D.
Harvard School of Public Health
NIEHS grantees have discovered a new way to determine biological age using ribosomal DNA (rDNA), which is the DNA segment responsible for providing genetic code required to produce new protein molecules. The study introduces a biological age clock that measures the status of DNA methylation, a type of chemical change to DNA that alters its expression, within the rDNA to estimate biological age.
Biological age is based on changes that accumulate over time in DNA and has been shown to be a more accurate way to predict the onset of some aging-related diseases. However, these DNA methylation site clocks across the genome have varied between studies of the same species and are often not the same across species. The new rDNA clock could serve as a more universal marker to gauge individual age in humans as well as laboratory and other organisms.
The researchers found that rDNA methylation status could predict age in humans and dogs, often much more accurately than a larger group of methylation sites in non-rDNA areas of the genome. They also found that the sites were the same in both species. Looking at these rDNA clock sites, they also determined that putting mice on a low-calorie diet, which generally makes animals live longer, led to less methylation and thus made the mice appear to age more slowly. According to the authors, this new biological clock is a useful tool for future studies to determine whether certain behaviors or exposures may speed up or slow down the aging process across different organisms.
Citation: Wang M, Lemos B. 2019. Ribosomal DNA harbors an evolutionarily conserved clock of biological aging. Genome Res 29(3):325–333.